Planar heating element and method for manufacturing the same

Abstract

The planar heating element includes a base film, a heating layer formed on the first surface of the base film, a pair of electrodes disposed on the first surface of the base film with the heating layer interposed therebetween and provided so as to be able to apply power to the heating layer, and a silicone insulating layer provided so as to cover the heating layer and the electrodes and formed integrally with the heating layer through a spray coating process or a casting process. Thereby, the planar heating element can have excellent heat resistance and withstand voltage characteristics.

Description

Technical Field

[0001] Embodiments of the present invention relate to a planar heating element and a method for manufacturing the same. More specifically, embodiments of the present invention relate to a planar heating element including a heating layer of a carbon component and an insulating layer formed to cover the heating layer, and a method for manufacturing the planar heating element.

Background Art

[0002] Planar heating elements are widely used in mats, pads, bed mattresses, and residential heating devices in general houses that require heating because they are easy to control temperature and produce no noise. A planar heating element includes a base film, a heating layer, and an insulating layer provided to cover the heating layer. A pair of electrodes is provided on the base film so that the heating layer can mainly generate heat using electricity. When electricity is applied to the electrodes, the heating layer can generate heat. At this time, the insulating layer electrically insulates the heating layer while protecting the heating layer from moisture or water.

[0003] The insulating layer can be mainly formed by laminating and attaching an insulating polymer film on the heating layer. In particular, among the insulating polymers, polyimide (hereinafter referred to as PI) has excellent heat resistance and is therefore a very suitable material for use as an insulating layer. In this case, as an adhesive for laminating the PI film on the heating layer, a silicone adhesive is very suitable in terms of heat resistance, insulation, adhesiveness, etc.

[0004] However, the silicone adhesive and the PI film have different shrinkage and expansion rates due to temperature changes. Therefore, when laminating the PI film using the silicone adhesive, the peeling phenomenon of the silicone adhesive easily occurs. In particular, the silicone adhesive has a problem that its insulation characteristics are destroyed at a high temperature state due to thermal decomposition at a temperature of 200°C or higher.

[0005] On the one hand, an insulating layer that can be used at a temperature of 200°C or higher contains a thermosetting substance, which has problems such as relatively low flexibility and deteriorated withstand voltage.

Summary of the Invention

Problems to be Solved by the Invention

[0006] An embodiment of the present invention for solving such problems provides a planar heating element having improved heat resistance and withstand voltage. An embodiment of the present invention provides a method for manufacturing a planar heating element having improved heat resistance and withstand voltage.

Means for Solving the Problems

[0007] The planar heating element according to an embodiment of the present invention includes a base film, a heating layer formed on the first surface of the base film, a pair of electrodes disposed on the first surface of the base film with the heating layer interposed therebetween and provided so as to be able to apply a power source to the heating layer, and a silicone insulating layer provided so as to cover the heating layer and the electrodes and integrally formed with the heating layer through a spray coating process or a casting process.

[0008] In one embodiment of the present invention, a heat insulating layer formed on the second surface of the base film is additionally provided. Here, the heat insulating layer can include a micro-porous foam layer.

[0009] In the method for manufacturing a planar heating element according to an embodiment of the present invention, a heating layer is formed on the first surface of a base film using a conductive paste, and a pair of electrodes is formed on the first surface of the base film with the heating layer interposed therebetween and provided so as to be able to apply a power source to the heating layer. Subsequently, a silicone insulating layer integrally formed with the heating layer through a spray coating process is formed so as to cover the heating layer and the electrodes.

[0010] In one embodiment of the present invention, the heating layer can be formed by any one method selected from the group consisting of screen printing, offset printing, gravure printing, flexographic printing, letterpress printing, inkjet printing, and roll-to-roll gravure printing.

[0011] In one embodiment of the present invention, the base film can be formed using one substance selected from the group consisting of PET (polyethylene terephthalate), PI (polyimide), PC (polycarbonate), PES (polyethersulfone), PAR (polyarylate), COC (cyclic olefin), and combinations thereof.

[0012] In one embodiment of the present invention, a heat insulation layer formed on the second surface of the base film can be additionally formed. Here, the heat insulation layer can be formed through the spray coating process.

Advantages of the Invention

[0013] According to an embodiment of the present invention, the planar heating element is provided to cover the heating layer and the electrodes, and includes a silicone insulation layer integrally formed with the heating layer through the spray coating process. Thereby, the planar heating element can ensure excellent heat resistance and insulation properties.

[0014] Furthermore, the planar heating element including the micro-porous foam layer can block the heat passing through the second surface with the micro-porous foam layer, and can control the heat generation direction by selectively generating heat with the silicone insulation layer through the first surface.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention should not be construed as being limited to the embodiments described below, and can be embodied in many other forms. The following embodiments are provided not so much to completely complete the present invention, but to fully convey the scope of the present invention to those skilled in the art of the present invention.

[0017] In the embodiments of the present invention, when an element is described as being disposed or connected (coupled) on another element, the above element can be directly disposed or connected (coupled) on the other element, and it is also possible for other elements to be interposed therebetween. In contrast, when an element is described as being directly disposed or connected (coupled) on another element, there are no further other elements therebetween. For describing various items such as various elements, compositions, regions, layers, and / or parts, terms such as first, second, third, etc. can be used, but the above items are not limited by these terms.

[0018] The technical terms used in the embodiments of the present invention are used only for the purpose of explaining specific embodiments and are not for limiting the present invention. Also, unless otherwise specifically limited, all terms including technical and scientific terms have the same meaning that can be understood by those skilled in the art of the present invention having ordinary knowledge. The above terms that are defined in a normal dictionary are construed to have a meaning consistent with their meaning from the context of the description of the related art and the present invention, and are not construed ideally or overly formally intuitively unless clearly limited.

[0019] Embodiments of the present invention will be described with reference to schematic illustrations of ideal embodiments of the present invention. Thus, changes from the shapes of the above illustrations, for example, changes in manufacturing methods and / or tolerances, are reasonably predictable. Therefore, embodiments of the present invention are not described as being limited to the specific shapes of the regions illustrated, include deviations in shape, and the elements depicted in the drawings are generally schematic in nature. These shapes are not for the purpose of illustrating the exact shapes of the elements, nor are they intended to limit the scope of the present invention.

[0020] FIG. 1 is a cross-sectional view for explaining a planar heating element according to an embodiment of the present invention. Referring to FIG. 1, a planar heating element 100 according to an embodiment of the present invention includes a base film 110, a heating layer 130, a pair of electrodes 150, and a silicone insulating layer 160.

[0021] The base film 110 can include an insulating film for flexibility. The base film 110 can include, for example, at least one material among PET (polyethylene terephthalate), PI (polyimide), PC (polycarbonate), PES (polyethersulfone), PAR (polyarylate), and COC (cyclo olefin).

[0022] The heating layer 130 is formed on the first surface of the base film 110. A power source can be applied to the heating layer 130 to perform a heating function. The heating layer 130 can be formed using a conductive paste.

[0023] The conductive paste can include conductive particles, a surfactant, and a solvent. The conductive particles can be composed of carbon nanotubes, graphene, copper, nickel, gold, silver, platinum, palladium, tin, aluminum, indium oxide, zinc oxide, tin oxide, and combinations thereof. For example, the conductive particles may preferably be carbon nanotubes, and the carbon nanotubes may be any one selected from the group consisting of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, and combinations thereof, and may preferably be single-walled carbon nanotubes.

[0024] In one embodiment of the present invention, the conductive paste can be formed by mixing a solution in which 5 to 15 parts by weight of carbon conductive particles such as graphene and carbon nanotubes and 1 to 10 parts by weight of a surfactant are dispersed to form a paste.

[0025] If the amount of the carbon conductive particles is less than 5 parts by weight, the conductivity is low and the calorific value is not sufficient. If it exceeds 15 parts by weight, the dispersibility deteriorates, so that the resistance of the heating part becomes non-uniform, and thereby the quality of the planar heating element may deteriorate.

[0026] On the other hand, if the amount of the surfactant is less than 1 part by weight, the dispersibility deteriorates, so that the resistance of the heating part becomes non-uniform. If it exceeds 10 parts by weight, the relative content of the carbon nanotubes decreases and the conductivity decreases, resulting in insufficient calorific value.

[0027] On the other hand, the surfactant prevents the aggregation of carbon nanotubes and improves the dispersibility. The surfactant may be one or more selected from the group consisting of cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants.

[0028] The solvent can include alpha-terpineol, N-methylpyrrolidone, butyl cellosolve, butyl cellosolve acetate, cellosolve, cellosolve acetate, Ethyl carbitol, Ethyl carbitol acetate, Butyl carbitol, Butyl carbitol acetate, Ethoxyethyl acetate, Butyl acetate, Propylene glycol monomethyl ether, Propylene glycol monomethyl ether acetate, γ-butyrolactone, methyl ethyl ketone, and mixtures thereof.

[0029] After dispersing the carbon conductive particles and the surfactant in the solvent, a conductive paste can be formed through a mixing and milling process. The heating layer 130 can be formed on the base film through a printing process. The printing process can include any one of screen printing, offset printing, gravure printing, flexographic printing, letterpress printing, inkjet printing, and roll-to-roll gravure printing processes.

[0030] The pair of electrodes 150 are disposed on the first surface of the base film 110 with the heating layer 130 interposed therebetween. The pair of electrodes 150 are electrically connected to the heating layer 130. Thereby, the pair of electrodes 150 can apply power to the heating layer 130.

[0031] Examples of the conductive material constituting the pair of electrodes 150 include metallic materials such as silver, zinc, aluminum, and copper. The silicone insulating layer 160 is provided so as to cover the heating layer 130 and the electrode 150. Thereby, the silicone insulating layer 160 can electrically insulate the heating layer 130 and the electrode 150 from the outside.

[0032] The silicone insulating layer 160 can have a thickness of 10 to 200 μm. More preferably, the silicone insulating layer 160 can have a thickness of 10 to 100 μm or 10 to 50 μm.

[0033] The silicone insulating layer 160 is formed through a spray coating process. Thereby, the silicone insulating layer 160 can be formed integrally with the heating layer 130. Therefore, by integrating the silicone insulating layer 160 with the heating layer 130, chemical resistance and physical resistance can be ensured.

[0034] That is, the silicone insulating layer 160 can maintain electrical insulation at a high temperature of at least 300°C. On the other hand, the silicone insulating layer 160 can maintain withstand voltage characteristics in an AC voltage state of 2 kV, and thus can have excellent insulation characteristics at a driving voltage of AC 220V. Thereby, the planar heating element 100 including the silicone insulating layer 160 can be applied not only for automobiles but also for industrial, household / office heating elements.

[0035] Also, the silicone insulating layer 160 can maintain excellent insulation characteristics even when the heating layer 150 generates heat at a temperature up to 300°C. In one embodiment of the present invention, a heat insulating layer 170 formed on the second surface of the base film 110 can be additionally provided. The heat insulating layer 170 can suppress the radiation of heat to the second surface of the base film 110. Thereby, the planar heating element 100 can limit the heat generation direction so that the heat generated from the heating layer 130 passes through the silicone insulating layer 160 through the first surface excluding the second surface of the base film 110.

[0036] Here, the heat insulation layer 170 can include a fine pore foam layer. The fine pore foam layer can include a substance containing thermoplastic microspheres encapsulating air, such as Expancel TM (manufactured by Nouryon).

[0037] By including microspheres in a state where air is encapsulated inside the fine pore foam layer, an excellent heat insulation effect, that is, a heat insulation effect, can be ensured. Therefore, the planar heating element 100 including the fine pore foam layer can block the heat passing through the second surface with the fine pore foam layer and selectively generate heat with the silicone insulating layer 160 through the first surface.

[0038] FIG. 2 is a flowchart for explaining a method of manufacturing a planar heating element according to an embodiment of the present invention. Referring to FIGS. 1 and 2, in a method of manufacturing a planar heating element according to an embodiment of the present invention, a heating layer 130 is formed on the first surface of a base film 110 using a conductive paste (S130).

[0039] The conductive paste can include conductive particles, a surfactant, and a solvent. The conductive particles can be composed of carbon nanotubes, graphene, copper, nickel, gold, silver, platinum, palladium, tin, aluminum, indium oxide, zinc oxide, tin oxide, and combinations thereof. For example, the conductive particles may preferably be carbon nanotubes, and the carbon nanotubes may be any one selected from the group consisting of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, and combinations thereof, and may preferably be single-walled carbon nanotubes.

[0040] In one embodiment of the present invention, the conductive paste can be formed by mixing a solution in which 5 to 15 parts by weight of carbon conductive particles such as graphene and carbon nanotubes and 1 to 10 parts by weight of a surfactant are dispersed to form a paste.

[0041] If the amount of the carbon conductive particles is less than 5 parts by weight, the conductivity is low and the calorific value is insufficient. If it exceeds 15 parts by weight, the dispersibility deteriorates, so that the resistance of the heat generating part becomes non-uniform, and thus the quality of the planar heating element may deteriorate.

[0042] On the other hand, if the amount of the surfactant is less than 1 part by weight, the dispersibility deteriorates, so that the resistance of the heat generating part becomes non-uniform. If it exceeds 10 parts by weight, the relative content of the carbon nanotubes decreases and the conductivity decreases, resulting in insufficient calorific value.

[0043] On the other hand, the surfactant prevents the aggregation of carbon nanotubes and improves the dispersibility. The surfactant may be one or more selected from the group consisting of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant.

[0044] The solvent can include alpha-terpineol, N-methylpyrrolidone, butyl cellosolve, butyl cellosolve acetate, cellosolve, cellosolve acetate, Ethyl carbitol, Ethyl carbitol acetate, Butyl carbitol, Butyl carbitol acetate, Ethoxyethyl acetate, Butyl acetate, Propylene glycol monomethyl ether, Propylene glycol monomethyl ether acetate, γ-butyrolactone, methyl ethyl ketone, and mixtures thereof.

[0045] After dispersing the carbon conductive particles and the surfactant in the solvent, a conductive paste can be formed through a mixing and milling process. The heating layer 130 can be formed on the base film through a printing process. The printing process can include any one of screen printing, offset printing, gravure printing, flexographic printing, letterpress printing, inkjet printing, and roll-to-roll gravure printing processes.

[0046] Next, a pair of electrodes 150 provided to apply power to the heating layer 130 are formed (S150) with the heating layer 130 sandwiched between them on the first surface of the base film 110. The pair of electrodes 150 can be formed through a printing process.

[0047] Next, a silicone insulating layer 160 formed integrally with the heating layer is formed through a spray coating process so as to cover the heating layer 130 and the electrode 150. Thereby, the silicone insulating layer 160 can be formed integrally with the heating layer 150 (S160). Therefore, by integrating the silicone insulating layer 160 with the heating layer 150, chemical resistance and physical resistance can be ensured.

[0048] That is, the silicone insulating layer 160 can maintain electrical insulation at a high temperature of at least 300°C. On the other hand, the silicone insulating layer 160 can have excellent insulation characteristics at a driving voltage of AC 220V by maintaining withstand voltage characteristics in an AC voltage state of 2kV.

[0049] In one embodiment of the present invention, a heat insulating layer 170 formed on the second surface of the base film can be additionally formed. Here, the heat insulating layer 170 can be formed through the spray coating process.

Industrial Applicability

[0050] The planar heating element and its manufacturing method according to the embodiment of the present invention can be applied to mats, pads, bed mattresses, and residential heating devices in ordinary houses that require heating.

Claims

1. A base film, A heat generating layer formed on a first surface of the base film, A pair of electrodes disposed on the first surface of the base film with the heat generating layer therebetween and provided so as to be able to apply power to the heat generating layer, and A silicone or urethane insulating layer provided so as to cover the heat generating layer and the electrodes and formed integrally with the heat generating layer through a spray coating or casting process A planar heating element comprising the same.

2. The planar heating element according to claim 1, further comprising a heat insulating layer formed on a second surface of the base film.

3. The planar heating element according to claim 2, wherein the heat insulating layer includes a fine pore foam layer.

4. A step of forming a heat generating layer on a first surface of a base film using a conductive paste, A step of forming a pair of electrodes provided so as to be able to apply power to the heat generating layer with the heat generating layer therebetween on the first surface of the base film, and A step of forming a silicone insulating layer formed integrally with the heat generating layer through a spray coating process so as to cover the heat generating layer and the electrodes A method for manufacturing a planar heating element comprising the same.

5. The step of forming the heat generating layer is performed by any one method selected from the group consisting of screen printing, offset printing, gravure printing, flexographic printing, letterpress printing, inkjet printing, and roll-to-roll gravure printing. The method for manufacturing a planar heating element according to claim 4.

6. The manufacturing method of the planar heating element according to claim 4, wherein the base film is formed using one substance selected from the group consisting of PET (polyethylene terephthalate), PI (polyimide), PC (polycarbonate), PES (polyether sulfone), PAR (polyarylate), COC (cycloolefin), and combinations thereof.

7. The manufacturing method of the planar heating element according to claim 4, further comprising the step of forming a heat insulation layer formed on the second surface of the base film.

8. The manufacturing method of the planar heating element according to claim 7, wherein the heat insulation layer is formed through the spray coating process.

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