Heat-generating film and planar heating element comprising same

Abstract

The present invention relates to a heat-generating film and a planar heating element comprising same, the heat-generating film being low in resistance and high in transmittance to provide rapid and even heating with excellent visibility, and can prevent localized overheating and provide even overall heating in the heat-generating electrode.

Description

Heating film and surface heating element including the same

[0001] The present invention relates to a heating film and a surface heating element including the same.

[0002] In the construction, automotive, railway, and aviation industries, fogging or frost caused by temperature differences between the interior and exterior of vehicles, helmets, and buildings has historically hindered visibility. Various attempts have been made to remove this fogging or frost, and a recent method has been developed to directly heat the glass by installing a conductive heating element, such as a tungsten wire or metal film, within the laminated glass.

[0003] Meanwhile, in application fields such as automobiles, aircraft, and helmets, there is a need to improve heating performance under limited current and voltage, but there is a problem in that uniform heating performance cannot be achieved across the entire heating element.

[0004] In addition, as electrons passing through the conductive heating element are concentrated in one direction, a hot spot phenomenon may occur in which only a part is overheated, and there were problems such as a decrease in heating performance or obstruction of the driver's view due to defects caused by such local overheating.

[0005] In this regard, Korean Patent Publication No. 10-2009-0099502 discloses a heating element and a manufacturing method thereof, comprising an irregular mesh pattern that maintains heating performance while not obstructing the driver's view. However, the structure in which busbars are formed on the mesh pattern suffers from problems such as reduced heating performance due to contact resistance and localized overheating.

[0006] In addition, when a large number of electrode lines are included per unit area to provide low resistance characteristics in order to improve the heating performance of the heating element, the transmittance is reduced, which causes a problem of obstructing the driver's view.

[0007] Therefore, there is a need for the development of a heating film that exhibits uniform heating performance within a short period of time, while preventing local overheating and having excellent transmittance.

[0008]

[0009] The purpose of the present invention is to provide a heating film having low resistance characteristics so as to exhibit uniform heating performance within a short period of time and excellent transmittance without a visible pattern.

[0010] In addition, the present invention aims to provide a heating film that can exhibit uniform heating performance within a short period of time while preventing local overheating by stably supplying power to a heating electrode.

[0011] In addition, the present invention aims to provide a heating film that can exhibit uniform heating performance in all areas by maintaining a uniform potential difference across the entire heating electrode.

[0012] In addition, the present invention aims to provide a surface heating element including the heating film.

[0013] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0014]

[0015] In order to solve the above problem, the present invention provides a heating film including a substrate, a heating electrode formed on the substrate and having a plurality of patterns, and a bus bar formed on the substrate and connected to both ends of the heating electrode, wherein the pattern is a square with at least one inner angle greater than 90° and less than 180°.

[0016] The above plurality of patterns may be in the form of a mesh in which openings are continuously repeated.

[0017] The above pattern may be a diamond shape with a longer diagonal length in the direction of the bus bar.

[0018] The above pattern may have a side length of 200 ㎛ to 1000 ㎛.

[0019] The above pattern may have a line width of 1 μm to 10 μm.

[0020] The above pattern may have one or more interior angles greater than 110° and less than 150°.

[0021] The above heating electrode may include a metal mesh.

[0022] The above heating electrode and bus bar may be formed of the same material.

[0023] The above heating electrode and bus bar may be formed on the same layer.

[0024] The above heating electrode and bus bar may be formed integrally in the same process step.

[0025] The above heating electrode and bus bar may have a thickness of 0.1 to 1 μm.

[0026] The above bus bar may include a first bus bar connected to both ends of the heating electrode; and a second bus bar formed on the first bus bar.

[0027] The above heating film may have a surface resistance of 4.5 Ω / □ or less and a transmittance of 88% or more.

[0028] The above heating film may further include at least one selected from the group consisting of a blackening layer, a separation protective layer, and an overcoating layer.

[0029] In addition, the present invention provides a surface heating element including the heating film.

[0030]

[0031] The present invention provides a heating film that can exhibit uniform heating performance within a short period of time while ensuring visibility by simultaneously providing low resistance characteristics and excellent transmittance.

[0032] In addition, the present invention can provide a heating film that can exhibit uniform heating performance within a short period of time by stably supplying power to a heating electrode, while preventing local overheating, thereby preventing damage to the substrate and deterioration of heating performance.

[0033] In addition, the present invention can provide a heating film that can exhibit uniform heating performance across the entire heating electrode by sufficiently lowering the resistance of the bus bar that supplies power to maintain a uniform potential difference across the entire heating electrode and preventing a decrease in the potential difference at the heating electrode located far from the power source.

[0034] In addition, the present invention can provide a surface heating element that is very useful in the transportation (transportation) industry such as vehicles, railways, aviation, helmets, etc. and the construction industry by including the heating film.

[0035]

[0036] Fig. 1 is a plan view of a heating film according to a first embodiment of the present invention.

[0037] Fig. 2 is a cross-sectional view of a heating film according to the first embodiment of the present invention.

[0038] Figures 3 to 8 are cross-sectional views of heating films according to the second to seventh embodiments of the present invention.

[0039] FIGS. 9 and 10 are plan views of a heating film according to some embodiments of the present invention connected to an external power source.

[0040] Fig. 11 is a cross-sectional view of a surface heating element according to the present invention.

[0041] Figures 12 and 13 are graphs showing the results of heat performance evaluation according to Experimental Example 4 for the examples and comparative examples of the present invention.

[0042]

[0043] What each symbol represents is as follows:

[0044] 10: Heating film 20: External member adhesive layer

[0045] 30: External Absence 40: External Power

[0046] 100: Base 200: Heating electrode

[0047] 210: Pattern 300: Busbar

[0048] 300-1: 1st bus bar 300-2: 2nd bus bar

[0049] 500: Blackening layer 600: Separating protective layer

[0050] 700: Overcoating layer

[0051]

[0052] The present invention relates to a heating film and a planar heating element including the same, and provides a heating film and a planar heating element including the same, which can exhibit uniform heating performance in a short period of time, have excellent transmittance without a visible pattern, can prevent local overheating, and can exhibit uniform heating performance over the entire heating electrode.

[0053] More specifically, the present invention provides a heating film comprising: a substrate; a heating electrode formed on the substrate and having a plurality of patterns; and a bus bar formed on the substrate and connected to both ends of the heating electrode, wherein the pattern is a square with at least one inner angle greater than 90° and less than 180°.

[0054] In addition, the present invention provides a surface heating element including the heating film.

[0055]

[0056] Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. However, the following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the contents of the invention described above, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited to the matters described in such drawings.

[0057] In this specification, singular forms also include plural forms, unless specifically stated otherwise. Throughout the specification, the same reference numerals refer to the same components. For example, "busbar" as used herein may refer to at least one of the first busbar and the second busbar.

[0058]

[0059] As used herein, the terms “comprises” and / or “comprising” are used to mean that they do not exclude the presence or addition of one or more other components, elements and / or devices other than the components, elements and / or devices mentioned.

[0060] Spatially relative terms such as "below," "below," "underside," "above," "top," and "upper side" can be used to easily describe the relationship between one element or component and another element or component, as depicted in the drawings. Spatially relative terms should be understood to include different directions of the elements during use or operation in addition to the directions depicted in the drawings. For example, if an element depicted in a drawing is flipped over, an element described as "below" or "below" another element may end up being placed "above" the other element. Thus, the exemplary term "below" can include both below and above directions.

[0061] As used herein, the term "connection" is used to mean both indirectly connecting and directly connecting multiple components, and to mean both physically connecting and electrically connecting.

[0062]

[0063] <Heating Film>

[0064] Figures 1 and 2 are a plan view and a cross-sectional view of a heating film according to a first embodiment of the present invention.

[0065]

[0066] Referring to FIGS. 1 and 2, a heating film (10) according to a first embodiment of the present invention includes a substrate (100), a heating electrode (200) formed on the substrate (100) and having a plurality of patterns; and a bus bar (300) formed on the substrate (100) and connected to both ends of the heating electrode (200), wherein the pattern may be a square with at least one inner angle greater than 90° and less than 180°.

[0067] The above substrate (100) serves to structurally support the heating electrode (200) and bus bar (300) and maintain their positions, and any film-type substrate commonly used in this field can be used without limitation. The above substrate (100) may be a transparent substrate that can transmit light, and may be one having flexible properties.

[0068] In one embodiment, the substrate (100) may include at least one selected from the group consisting of polymeric materials such as glass, cyclic olefin polymer (COP), polyethylene terephthalate (PET), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polyallylate, polyimide (PI), cellulose acetate propionate (CAP), polyethersulfone (PES), cellulose triacetate (TAC), polycarbonate (PC), cyclic olefin copolymer (COC), polymethyl methacrylate (PMMA); and / or inorganic insulating materials such as silicon oxide, silicon nitride, silicon oxynitride, and metal oxide.

[0069] The thickness of the above substrate (100) may be 1 to 500 μm, and preferably 5 to 75 μm. When the thickness of the substrate (100) satisfies the above range, it is preferable because it has the advantage of maintaining a stable structure while having transparent and flexible characteristics, making it easy to handle in the process.

[0070]

[0071] The above heating electrode (200) is formed on one surface of the above substrate (100).

[0072] In one embodiment, the heating electrode (200) has a plurality of patterns (210), and the patterns (210) may be squares with at least one inner angle (α) greater than 90° and less than 180°, and the plurality of patterns may be in the form of a mesh in which openings are continuously repeated.

[0073] In the present invention, the opening may be a region where no pattern is formed, and more specifically, may be defined by the mesh pattern. The openings may have the same shape and the same area, but are not limited thereto.

[0074] The shape of the opening of the above pattern (210) may be a square shape, and preferably, it is a diamond shape in which the diagonal length in the direction of the bus bar (300) connected to both ends of the heating electrode (200) is longer, so that the line in the direction of the bus bar (300) at both ends of the heating electrode (200) is shortened, thereby reducing the path through which the current moves, and by minimizing the difference in resistance generated by the distance from the bus bar (300) in the entire area of ​​the heating electrode (200), it is advantageous in achieving equipotential by reducing the potential difference, thereby enabling uniform heating.

[0075] In the specification of the present invention, the direction of the bus bar (300) means the direction from the bus bar on one side to the bus bar on the other side.

[0076] The pattern (210) of the above heating electrode (200) may have at least one internal angle (α) greater than 90° and less than 180°, preferably greater than 110° and less than 150°, so as to achieve equipotential over the entire heating area.

[0077] The pattern (210) of the above heating electrode (200) may have a side length (p) of 200 µm to 1000 µm, preferably 250 µm to 700 µm.

[0078] When the length (p) of one side of the pattern (210) of the above heating electrode (200) satisfies the above range, the number of heating electrodes (200) included per unit area of ​​the heating film is appropriate, so that the pattern is not visible, the transmittance is not a problem, and uniform heating performance can be sufficiently exhibited within a short period of time, which is preferable.

[0079] The pattern (210) of the above-described heating electrode (200) may have a line width (CD) of 1 µm to 10 µm, preferably 1.5 µm to 7 µm. When the line width of the heating electrode (200) satisfies the above range, sufficient heating performance can be exhibited without lowering the transmittance, which is preferable. The heating film of the present invention may have a surface resistance of 4.5 Ω / □ or less and a transmittance of 88% or more by including the heating electrode (200) having the above-described pattern (210).

[0080] When the above surface resistance is satisfied, the current movement through the heating electrode (200) is smooth, so there is an advantage in that the target temperature can be reached more quickly.

[0081] In addition, in the case of having the above-described pattern, it is possible to secure visibility by satisfying the above transmittance without increasing the number of heating electrodes (200) included per unit area of ​​the heating film to quickly reach the desired temperature.

[0082]

[0083] The material for forming the above heating electrode (200) is not particularly limited, but a component having transparency may be preferable.

[0084] It may include at least one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), carbon nanotubes (CNT), graphene, and metals, and the metals are not particularly limited. Examples thereof include silver (Ag), gold (Au), aluminum (Al), copper (Cu), molybdenum (Mo), nickel (Ni), zinc (Zn), tungsten (W), titanium (Ti), tellurium (Te), chromium (Cr), etc. and preferably copper (Cu). These can be used alone or in combination of two or more.

[0085] The heating electrode (200) is physically directly connected to a bus bar (300) at both ends, so that current flows between the positive and negative electrodes and heat is generated. In order to generate heat uniformly throughout the heating electrode (200), a pair of bus bars (300) facing the heating electrode (200) may be formed to be parallel to each other, but is not limited thereto. In one embodiment of the present invention, the bus bar (300) may form a straight line, and the heating electrode (200) may have a rectangular shape, but is not limited thereto, and may have a suitable shape depending on the shape of the transportation means, device, or building to which the heating film (10) is applied.

[0086]

[0087] The thickness of the above heating electrode (200) may be 0.1 to 1 μm, and preferably 0.3 to 0.8 μm. When the heating electrode (200) satisfies the above thickness, there is an advantage in that the taper of the heating electrode (200) can be appropriately adjusted, thereby reducing the defect rate in the heating film manufacturing process and improving ESD (electrostatic discharge) durability, thereby increasing the reliability of the product, which is preferable.

[0088] The taper of the above heating electrode (200) may be a forward taper, and preferably may have an angle of 20 to 50°. As the thickness of the heating electrode (200) increases, the taper angle may deviate from the appropriate range, and if a reverse taper or a sharp taper is formed, there may be problems such as an unintentional short circuit in the electrical connection between the upper and lower layers, or the formation of microbubbles between each layer during the lamination process.

[0089] The above bus bar (300) provides a path through which current (or electrons) supplied from an external power source (40) moves. In one embodiment of the present invention, the bus bar (300) is connected to an external power source (40), and the current (or electrons) supplied from the external power source (40) may flow from one end of the heating electrode (200) to the other end through the bus bar (300) and generate heat.

[0090] The above bus bar (300) may include at least one selected from the group consisting of carbon (C), silver (Ag), gold (Au), aluminum (Al), copper (Cu), molybdenum (Mo), nickel (Ni), zinc (Zn), tungsten (W), titanium (Ti), tellurium (Te), and chromium (Cr). The carbon may be, but is not limited to, carbon nanotubes (CNT) or graphene.

[0091]

[0092] The above heating electrode (200) and bus bar (300) may be formed of the same material. By forming the heating electrode (200) and bus bar (300) of the same material, the occurrence of contact resistance due to contact between two different materials can be prevented. Accordingly, by reducing the current bottleneck phenomenon due to uneven resistance at the connection between the bus bar (300) and the heating electrode, uniform heating performance can be exhibited throughout the heating electrode (200), and there is an advantage in that heating time delay and heat loss due to decreased electron mobility between dissimilar metals can be prevented.

[0093]

[0094] In addition, the heating electrode (200) and the bus bar (300) may be formed on the same layer. For example, in the conventional heating film, the heating electrode is first formed on the substrate, and the bus bar is formed as a separate layer on top of both ends of the formed heating electrode. However, when the heating electrode and the bus bar are formed on different layers and connected in this way, contact resistance may occur between the bus bar and the heating electrode layer, and the resulting increase in resistance may deteriorate the heating performance. In addition, when the heating film is bonded to a cover glass or the like through a heat-sealing or laminating process, an electrical short circuit may occur with the bus bar, which is an upper layer, due to the tapered step of the mesh-shaped heating electrode, and thus, a problem may occur in which the overall resistance increases.

[0095]

[0096] In addition, the heating electrode (200) and the bus bar (300) may be formed integrally in the same process step. If the heating electrode (200) and the bus bar (300) are formed in different layers in different process steps and then connected, the above-described problem may occur. In addition, if the heating electrode (200) and the bus bar (300) are formed in different process steps and then connected in the same layer, a problem may occur in which a local overheating phenomenon or uneven heating performance occurs due to uneven contact area or poor contact. In addition, as described above, if the bus bar and the heating electrode are formed in separate layers and then connected, the resistance may increase due to an increase in contact resistance and an electrical short circuit between the upper and lower layers.

[0097]

[0098] The thickness of the above bus bar (300) is the same as the thickness of the above heating electrode (200), and may be 0.1 to 1 μm, and preferably 0.3 to 0.8 μm. When the bus bar (300) satisfies the above thickness, there is an advantage in that the taper can be appropriately adjusted, and accordingly, the defect rate in the heating film manufacturing process can be reduced, and the ESD (electrostatic discharge) durability can be improved, thereby increasing the reliability of the product, which is preferable.

[0099]

[0100] The width of the busbars (300) may be independently 50 mm or less, but is not limited thereto, and may be appropriately adjusted depending on the form of the means of transportation, device, or building to which the heating film (10) is applied. For example, when the diagonal width of the heating film (10) is 20 inches or less, the width of the busbars (300) may be independently 1 mm to 6 mm, and when the diagonal width of the heating film (10) is 20 inches or more, the width of the busbars (300) may be independently 2 mm to 50 mm. When the width of the busbars (300) satisfies the above range, there is an advantage in that current (electrons) can be stably supplied to the heating electrodes (200) without a problem of visibility. When the width of the busbars (300) exceeds the above range, the area through which current flows increases, so that the surface resistance may decrease. However, there is a problem in that the visibility of the busbars increases, making it difficult to apply it to actual products.

[0101]

[0102] The above heating electrode (200) and bus bar (300) can be formed by a method known in the art. For example, the method can be screen printing, photolithography, electroplating, or metal bonding, but is not limited thereto.

[0103] The bus bar (300) of the present invention may include a first bus bar (300-1) connected to both ends of the heating electrode (200); and a second bus bar (300-2) formed on the first bus bar (300-1).

[0104] The description of the above-described bus bar (300) can be applied equally to the first bus bar (300-1).

[0105] In the case where the above bus bar (300) is multi-layered, the second bus bar (300-2) is connected to an external power source (40), and current (or electrons) supplied from the external power source (40) may sequentially flow from one end of the heating electrode (200) to the other end through the second bus bar (300-2) and the first bus bar (300-1) to generate heat.

[0106] The first bus bar (300-1) and the second bus bar (300-2) may each independently include at least one selected from the group consisting of carbon (C), silver (Ag), gold (Au), aluminum (Al), copper (Cu), molybdenum (Mo), nickel (Ni), zinc (Zn), tungsten (W), titanium (Ti), tellurium (Te), and chromium (Cr). The carbon may be, but is not limited to, carbon nanotubes (CNT) or graphene.

[0107] The second bus bar (300-2) may be formed using a conductive paste. The conductive paste may include at least one selected from the group consisting of carbon (C), silver (Ag), gold (Au), aluminum (Al), copper (Cu), molybdenum (Mo), nickel (Ni), zinc (Zn), tungsten (W), titanium (Ti), tellurium (Te), and chromium (Cr). In terms of implementing low surface resistance, it is preferable to include silver (Ag) or gold (Au), and it is most preferable to include silver (Ag).

[0108]

[0109] In addition, the heating electrode (200) and the second bus bar (300-2) may not be in physical contact with each other. As shown in FIG. 3, the heating electrode (200) and the first bus bar (300-1) are formed on the same layer on the substrate (100) and are in physical contact with each other, and the second bus bar (300-2) is formed on the first bus bar (300-1) and is in physical contact with the first bus bar (300-1). However, the heating electrode (200) and the second bus bar (300-2) are not in physical contact with each other.

[0110] As described above, the second bus bar (300-2) is formed in a double layer on the first bus bar (300-1), and the second bus bar (300-2) exhibits a resistance similar to or lower than that of the first bus bar (300-1), thereby forming a parallel resistance, thereby assisting the smooth flow of current (electrons) applied from an external power source, thereby reducing the resistance of the current flowing throughout the bus bar. By reducing the resistance of the entire bus bar in this way, local overheating due to current bottlenecks in some sections can be prevented, and equipotential can be maintained throughout the heating electrode (200) connected to the first bus bar (300-1). However, when the heating electrode (200) and the second bus bar (300-2) are in physical contact with each other, a problem may occur in which the electrical connection with the second bus bar (300-2) is short-circuited due to the tapered step of the heating electrode (200).

[0111] It is preferable that the second bus bar (300-2) does not exceed the width and length of the first bus bar (300-1), and in order to minimize resistance, it is more preferable that the second bus bar (300-2) has the same width and length as the first bus bar (300-1).

[0112]

[0113] The second bus bar (300-2) may have a surface resistance similar to or lower than that of the first bus bar (300-1). By forming the second bus bar (300-2) having a surface resistance similar to or lower than that of the first bus bar (300-1) on the first bus bar (300-1), it is possible to prevent local overheating due to a current bottleneck at a connection portion connected to an external power source, and by supplying a stable and uniform current (electron) to the entire first bus bar (300-1), it is possible to exhibit uniform heating performance throughout the heating electrode (200).

[0114]

[0115] The thickness of the second bus bar (300-2) may be 5 to 100 times greater than the thickness of the first bus bar (300-1), and preferably 10 to 50 times greater. When the second bus bar (300-2) satisfies the above thickness ratio, it is preferable because it is easy to adjust it to exhibit resistance similar to or lower than that of the first bus bar (300-1).

[0116] The thickness of the second bus bar (300-2) may be 3 to 30 μm, and preferably 5 to 25 μm. When the second bus bar (300-2) satisfies the above thickness, it exhibits sufficiently low surface resistance, which has the advantage of preventing local overheating and supplying uniform current.

[0117]

[0118] The ratio (Rs1 / Rs2) of the surface resistance (Rs1) of the first bus bar (300-1) to the surface resistance (Rs2) of the second bus bar (300-2) may be 0.1 to 5, preferably 0.2 to 3, and more preferably 0.4 to 1.7. When the above-mentioned ratio of surface resistances is satisfied, uniform heating performance can be achieved throughout the entire heating film by reducing the potential difference between the first and second bus bars, which is preferable.

[0119] The surface resistance of the second bus bar (300-2) may be 0.5Ω / □ or less, preferably 0.1Ω / □ or less, and more preferably 0.01 to 0.1Ω / □.

[0120]

[0121] The heating film of the present invention may further include at least one selected from the group consisting of a blackening layer, a separation protective layer, and an overcoating layer.

[0122]

[0123] The heating film (10) according to FIG. 4 further includes a blackening layer (500) on one side of the heating electrode (200). The heating film (10) according to FIG. 5 further includes a blackening layer (500) on both sides of the heating electrode (200). Thus, the description given for the heating film according to FIGS. 1 to 3 can be equally applied to the heating film illustrated in FIGS. 4 and 5, and detailed descriptions of substantially identical or similar configurations are omitted.

[0124]

[0125] If the above heating electrode (200) includes a material that reflects light in the visible light range, such as metal, problems such as glare may occur due to the visibility of the heating electrode (200) being visible to the human eye and the high reflectivity to external light.

[0126] Accordingly, the heating film (10) of the present invention may further include a blackening layer (500) on one or both sides of the heating electrode (200), thereby reducing the reflectivity of the heating electrode (200) and preventing problems such as visibility and glare.

[0127] When the above busbar is formed in multiple layers, the first busbar (300-1) and the second busbar (300-2) can be formed in parallel with the blackening layer (500) interposed therebetween.

[0128] In this case, the second bus bar (300-2) may be formed at a position corresponding to the upper portion of the first bus bar (300-1) on the blackening layer (500). The first bus bar (300-1) and the second bus bar (300-2) provide a path through which current (or electrons) supplied from an external power source (40) travel. In one embodiment of the present invention, the second bus bar (300-2) may be connected to an external power source (40), and the current (or electrons) supplied from the external power source (40) may sequentially flow from one end of the electrode layer (200) to the other end through the second bus bar (300-2), the blackening layer (500), and the first bus bar (300-1) to generate heat.

[0129] The above blackening layer (500) can be formed of a material that does not hinder the movement of current (electrons) supplied from an external power source from the second bus bar (300-2) to the first bus bar (300-1).

[0130] The above blackening layer (500) can be formed, for example, using a composition for forming a blackening layer. The composition for forming a blackening layer can include at least one selected from the group consisting of manganese (Mn), cobalt (Co), nickel (Ni), iron (Fe), copper (Cu), titanium (Ti), and vanadium (V). More specifically, the blackening layer can be formed by including an oxide containing the metal. Examples of the oxide containing the metal include Al2O3, Fe2O3, TiO2, MnO3, Cr2O3, Cu2O, CuO, Cu2O3, ZnO, NiO, etc.

[0131] As described above, by forming a blackening layer (500) on the heating electrode (200), the problem of contact resistance occurring due to oxidation of the surface of the heating electrode (200) can be improved, thereby improving the reliability of the electrode.

[0132] The above blackening layer (500) may be formed, for example, using a composition for forming a blackening layer, deposited through a deposition process such as sputtering, or formed by electrolytic plating, but is not limited thereto.

[0133] When the heating film (10) of the present invention includes a blackening layer (500), the blackening layer (500) may have a thickness of 0.01 to 1 ㎛ in order to prevent problems such as visibility and glare of the heating electrode while not reducing the heating performance.

[0134]

[0135] The heating film (10) according to FIG. 6 further includes a separation protective layer (600) between the substrate (100) and the heating electrode (200). Accordingly, the description described for the heating film according to FIGS. 1 to 3 can be equally applied to the heating film illustrated in FIG. 6, and detailed descriptions of substantially identical or similar configurations are omitted.

[0136]

[0137] The heating film (10) of the present invention may further include a separation protective layer (600) therebetween to improve the adhesive strength between the substrate (100) and the heating electrode (200). The separation protective layer (600) may be formed using an adhesive, and it is preferable that it have appropriate adhesive strength to prevent peeling, bubbles, etc. from occurring when handling the heating film (10), while also having transparency and thermal stability.

[0138] The above adhesive may be any adhesive used in the present field without limitation, and for example, a photocurable adhesive may be used. The photocurable adhesive exhibits strong adhesive strength by being crosslinked and cured by receiving active energy rays such as ultraviolet (UV) rays and electron beams (EB), and may include polyester resins, polyether resins, polyurethane resins, epoxy resins, polyacrylic resins, and silicone resins.

[0139] When the heating film (10) of the present invention includes a separation protective layer (600), the separation protective layer (600) may have a thickness of 0.1 to 10 µm, preferably 1 to 5 µm, in order to secure sufficient adhesive strength and minimize its thickness.

[0140]

[0141] The heating film (10) according to FIGS. 7 and 8 further includes an overcoating layer (700) at the top, and the description given for the heating film according to FIGS. 1 to 6 can be equally applied to the heating film shown in FIGS. 7 and 8, and detailed descriptions of substantially identical or similar configurations are omitted.

[0142]

[0143] The heating film (10) of the present invention may include an overcoating layer (700) at the uppermost part of the heating film (10) to prevent damage to the heating electrode (200) and further improve mechanical durability.

[0144] The above overcoating layer (700) may include at least one selected from the group consisting of polyacrylic resin, polyurethane resin, polyolefin resin, polyester resin, epoxy resin, melamine resin, polyamide resin, polycarbonate resin, cellulose resin, and combinations thereof.

[0145] When the heating film (10) of the present invention includes an overcoating layer (700), the overcoating layer (700) may have a thickness of 0.1 to 10 µm, preferably 1 to 5 µm, in order to secure sufficient mechanical durability while preventing cracks due to bending, etc.

[0146]

[0147] Figures 9 and 10 are plan views of a heating film (10) according to some embodiments of the present invention connected to an external power source (40).

[0148]

[0149] As described above, the external power source (40) can be electrically connected to the second bus bar (300-2), and the power applied from the external power source (40) to the second bus bar (300-2) is applied to the heating electrode (200) via the first bus bar (300-1), and the heating electrode (200) is heated through the flow of current (electrons) accordingly.

[0150]

[0151] As shown in Fig. 9, the external power source (40) may be connected to both ends of the bus bar (300). When the heating film (10) of the present invention is applied to a means of transportation or a device, by connecting the external power source (40) to the end of the bus bar (300), the wiring from the external power source (40) to the bus bar (300) can be connected at the shortest distance, thereby increasing design efficiency.

[0152] Meanwhile, the heating film (10) according to the present invention can reduce the longest path for current to travel by satisfying the shape of a rectangle in which at least one inner angle (α) of the heating electrode (200) exceeds 90° and is less than 180°, as described above, even when the external power source (40) is connected to the end of the bus bar (300), thereby reducing the potential difference across the entire heating electrode (200), and thus exhibiting uniform heating performance.

[0153]

[0154] As shown in Fig. 10, the external power source (40) may be connected to the center of both sides of the bus bar (300). When the external power source (40) is connected to the center of the bus bar (300), the longest path along which current (electrons) travels can be shortened compared to when the external power source (40) is connected to the end of the bus bar (300), and accordingly, it is easy to exhibit an equipotential across the entire heating electrode (200), so there is an advantage in that more uniform heating performance can be exhibited.

[0155]

[0156] <Face heating element>

[0157] Fig. 11 is a cross-sectional view of a surface heating element according to the present invention.

[0158] Referring to FIG. 11, the surface heating element of the present invention may include the surface heating film (10), the external member adhesive layer (20), and the external member (30) of the present invention.

[0159] The above external member adhesive layer (20) is for bonding the surface film (10) and the external member (30), and may be formed using EVB (Ethyl vinyl benzene), PVA, EVA, PU, ​​etc.

[0160] The above external member (30) may be a glass or plastic substrate, and the contents of the aforementioned substrate (100) may be equally applied. The external member (30) is a target on which fogging or frosting occurs, and when the surface film (10) of the present invention is applied, fogging or frosting formed inside and outside the external member (30) can be removed in a short period of time.

[0161] The surface heating element of the present invention can be applied to various fields such as, but not limited to, the construction industry such as building windows; transportation means such as vehicles, railways or aviation; helmets; and smart glasses.

[0162]

[0163] Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended to further illustrate the present invention, and the scope of the present invention is not limited by the following examples.

[0164]

[0165] Examples and Comparative Examples: Manufacturing of Heating Film

[0166] A copper layer (Cu) with a thickness of 8000Å was formed on a 150 X 150mm glass substrate (0.5T Soda lime Eagle XG Glass, Corning) through vapor deposition, and the heating electrode and the bus bars at both ends of the heating electrode were formed as one piece.

[0167] After patterning the etching resist material on the copper layer (Cu) corresponding to the above heating electrode through a photolithography process, a pattern was formed through an etching process.

[0168] Examples 1 to 10 and Comparative Examples 1 to 2 were patterned to form a mesh shape in which the inner angle of the pattern (α, see FIG. 1), the length of one side (p, see FIG. 1), and the line width had the values ​​in Table 1 below, thereby forming a heating electrode. Comparative Examples 3 to 6 were patterned to form a triangle shape, but the angle (α) of the angle facing the base, the length of each of the two sides forming the angle, and the line width had the values ​​in Table 1 below, thereby forming a heating electrode. Comparative Examples 7 and 8 were patterned to form a straight line shape, thereby forming a heating electrode.

[0169] Internal angle (α, °) Length of one side (p, ㎛) Line width (㎛) Notes Example 1 1 2 0 3 5 0 3.3 Square Example 2 1 2 0 5 0 0 3.4 Square Example 3 1 3 0 5 0 0 3.5 Square Example 4 1 4 0 5 0 0 3.6 Square Example 5 1 1 0 5 0 0 3.7 Square Example 6 1 5 0 5 0 0 3.4 Square Example 7 1 0 0 2 0 0 3.4 Square Example 8 1 0 0 1 0 0 7 Square Example 91702003.5Rectangle Example 1017010003.5Rectangle Comparison Example 1903503.3Rectangle Comparison Example 2905003.5Rectangle Comparison Example 3605003.4Triangle Comparison Example 4305003.7Triangle Comparison Example 5851903.5Triangle Comparison Example 68511003.7Triangle Comparison Example 7-Interval between two straight lines 3503.6Straight line comparison example 8-Interval between two straight lines 5003.7Straight line

[0170] Experimental Example 1: Surface Resistance Measurement

[0171] For the heating films of the examples and comparative examples, the surface resistance of the heating electrode was measured using RESISTAGE RG-80 (analysis stage probing) and RESISTEST RT-80 (analyzer) of NAPSON CORPORATION, and the results are shown in Table 2 below.

[0172]

[0173] Experimental Example 2: Transmittance Measurement

[0174] For the heating films of the examples and comparative examples, the total light transmittance (Tt) was measured using a haze meter HM-150N (Murakami), and the results are shown in Table 2 below.

[0175]

[0176] Experimental Example 3: Pattern Visibility Evaluation

[0177] After fixing the heating film of the examples and comparative examples to the evaluation stand, an LED light source (Galaxy S22 flash LED) was installed in front of the sample at a distance of 15 cm to reflect light, and then 10 evaluators evaluated the pattern visibility with the naked eye at a distance of 30 cm from the front of the sample. The number of people who recognized the electrode pattern is shown in Table 2 below.

[0178]

[0179] Sheet resistance (Ω / □) Transmittance (%) Visibility (light) Example 14.189.451 Example 24.390.300 Example 33.590.040 Example 42.789.612 Example 54.590.460 Example 62.088.861 Example 72.587.103 Example 84.6392.101 Example 92.988.102 Example 101.990.203 Comparative Example 14.989.837 Comparative Example 27.390.575 Comparative Example 37.490.304Comparative Example 414.990.173Comparative Example 55.991.208Comparative Example 66.2191.707Comparative Example 77.0992.509Comparative Example 87.4492.9010

[0180] Referring to Table 2 above, it can be confirmed that the films including the electrode patterns of the present invention of Examples 1 to 10 have a surface resistance sufficient to allow the current of the supplied power to flow without a problem, have an appropriate transmittance so that visibility is not reduced, and have excellent visibility because the pattern is not visible.

[0181] In this regard, it can be confirmed that the substrate including the electrode patterns of Comparative Examples 1 to 8 not only has the electrode pattern of Cu metal recognized, resulting in reduced visibility, but also has high surface resistance, resulting in reduced heat generation performance.

[0182]

[0183] Experimental Example 4: Evaluation of Heat Generation Performance

[0184] In order to confirm the heat generation performance in environments of -20℃ and 25℃, a temperature sensor (thermocouple, Thermal Management Utility, Microchip) was attached to the surface of the heat generation film manufactured in the above examples and comparative examples, and a voltage of 18 V and a current of 3.2 A were applied to both ends of the bus bar, and the temperature was measured. The temperature change graph over time is shown in FIGS. 12 and 13.

[0185] As a result of the above heat generation performance evaluation, it can be confirmed that the heat generation films according to Examples 2, 4 and 6 reach a stable heat generation temperature earlier than Comparative Example 2 in a 25°C environment, and that the reached temperature is also higher.

[0186] In addition, it can be confirmed that the heating film according to Example 2 reaches a stable heating temperature much earlier than Comparative Example 2 even in a -20°C environment, and that the reached temperature is also very high.

[0187]

[0188] A heating film and a surface heating element including the same according to one embodiment of the present invention can exhibit uniform heating performance within a short period of time while preventing local overheating, and have excellent transmittance without a visible pattern.

Claims

1. Description; A heating electrode formed on the above substrate and having a plurality of patterns; and A bus bar formed on the above substrate and connected to both ends of the heating electrode, The above pattern is a heating film in which at least one inner angle is a square exceeding 90° and less than 180°.

2. In claim 1, A heating film wherein the above plurality of patterns are in the form of a mesh in which openings are continuously repeated.

3. In claim 1, The above pattern is a heating film in the shape of a diamond with a longer diagonal length in the direction of the bus bar.

4. In claim 1, The above pattern is a heating film having a side length of 200㎛ to 1000㎛.

5. In claim 1, The above pattern is a heating film having a line width of 1 ㎛ to 10 ㎛.

6. In claim 1, The above pattern is a heating film in which at least one inner angle is greater than 110° and less than 150°.

7. In claim 1, The above heating electrode is a heating film including a metal mesh.

8. In claim 1, A heating film wherein the above heating electrode and bus bar are formed of the same material.

9. In claim 1, A heating film wherein the above heating electrode and bus bar are formed on the same layer.

10. In claim 1, A heating film wherein the above heating electrode and bus bar are formed integrally in the same process step.

11. In claim 1, The above heating electrode and bus bar are heating films having a thickness of 0.1 to 1 ㎛.

12. In claim 1, The above bus bar is a first bus bar connected to both ends of the heating electrode; and A heating film comprising a second bus bar formed on the first bus bar.

13. In claim 1, A heating film having a surface resistance of 4.5 Ω / □ or less and a transmittance of 88% or more.

14. In claim 1, A heating film, wherein the heating film further comprises at least one selected from the group consisting of a blackening layer, a separation protective layer, and an overcoating layer.

15. A surface heating element comprising the heating film of claim 1.

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