Heating film and planar heating element comprising same

Abstract

The present invention relates to a heating film and a planar heating element comprising same, and can provide a heating film and a planar heating element comprising same, wherein the heating film prevents an increase in contact resistance, prevents a change over time and corrosion, exhibits uniform heating performance within a short time, prevents a localized overheating phenomenon, and exhibits uniform heating performance throughout a heating electrode.

Description

Heating film and planar heating element including the same

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

[0002] In the construction industry or in transportation industries such as vehicles, railways, and aviation, there have been problems where visibility is obstructed due to fogging or frost caused by temperature differences between the inside and outside of vehicles, helmets, or buildings. Various attempts to remove such fogging or frost have been made to date, and recently, a method has been devised to directly heat the glass by installing a conductive heating element, such as a tungsten wire or a metal thin film, inside the laminated glass.

[0003] Meanwhile, in application fields such as automobiles, aircraft, and helmets, there is a need to increase heating performance under limited current and voltage, but there is a problem in that uniform heating performance is not exhibited across the entire front surface of the heating element. In addition, as electrons passing through the conductive heating element become concentrated in one direction, a hot spot phenomenon may occur where only a part of it overheats, and there have been problems such as reduced heating performance or obstruction of the driver's view due to defects caused by such localized overheating.

[0004] In this regard, Korean Published Patent Application No. 10-2009-0099502 discloses a heating element including an irregular mesh pattern that maintains heating performance without obstructing the driver's view, and a method for manufacturing the same. However, due to the structure in which a bus bar is formed on the mesh pattern, there is a problem of reduced heating performance due to contact resistance and localized overheating.

[0005] In addition, as the conductive heating element is provided in the form of a metal pattern, there is a problem that the contact resistance increases because the contact area with the FPCB or conductive tape is narrow, and there is a problem that changes occur over time because the upper and side surfaces of the metal pattern are exposed.

[0006] Accordingly, there have been cases where a passivation layer was formed on the metal pattern to prevent corrosion of the metal pattern; however, when forming an organic or inorganic film for corrosion prevention in this manner, there is a problem in that a hole process must be added to provide heat generation performance.

[0007] Therefore, there is a need to develop a heating film that exhibits uniform heating performance within a short period of time, prevents localized overheating caused by an increase in contact resistance, and prevents corrosion of the electrode without additional processes.

[0008]

[0009] The present invention aims to provide a heating film capable of preventing an increase in contact resistance due to a reduction in contact area as the heating electrode is provided in a patterned form.

[0010] In addition, the present invention aims to provide a heating film that can prevent corrosion and changes over time caused by exposure of the pattern without additional processes, as the heating electrode is formed in a patterned shape.

[0011] 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 localized overheating by stably supplying power to the heating electrode.

[0012] In addition, the present invention aims to provide a heating film capable of exhibiting uniform heating performance in all parts by maintaining a uniform potential difference across the entire heating electrode.

[0013] In addition, the present invention aims to provide a planar heating element comprising the heating film.

[0014] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below.

[0015]

[0016] To solve the above problem, the present invention provides a heating film comprising: a substrate layer; a heating electrode formed on the substrate layer and having a pattern; and a transparent electrode laminated between the patterns of the heating electrode and on the upper surface.

[0017] The heating electrode may be formed by including at least one selected from silver (Ag), gold (Au), aluminum (Al), copper (Cu), molybdenum (Mo), nickel (Ni), zinc (Zn), tungsten (W), titanium (Ti), tellurium (Te), chromium (Cr), and alloys containing at least one of these.

[0018] The above transparent electrode may be formed by including one or more selected from the group consisting of carbon nanotubes (CNT), graphene, silver nanowires (AgNW), polypyrrole, polythiophene, polyacetylene, PEDOT, polyaniline, indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), fluorine tin oxide (FTO), and zinc oxide (ZnO).

[0019] The heating film above may have a resistance of 1Ω to 20Ω.

[0020] The above heating film may have a resistance difference of 2Ω or less before and after attaching a conductive tape to one side of a transparent electrode.

[0021] The heating electrode may include one or more types selected from the group consisting of metal wire and metal mesh.

[0022] The metal wire may include a plurality of wavy patterns.

[0023] The heating electrode may include a pattern with a line width of 0.5 μm to 30 μm.

[0024] The above heating electrodes may have a spacing distance between patterns of 30㎛ to 2500㎛.

[0025] The above transparent electrode may have a height of 100 Å to 2000 Å from the upper surface of the heating electrode.

[0026] The above heating film may have a total light transmittance of 80% or more.

[0027] It may include a conductive tape attached to one surface of the above transparent electrode.

[0028] It may include a busbar connected to both ends of the heating electrode.

[0029] The heating electrode and the busbar may be formed on the same layer using the same material.

[0030] The heating electrode and the busbar may be formed integrally in the same process step.

[0031] The above heating electrode may further include a blackened layer on one or both sides.

[0032] The above heating film may further include one or more selected from the group consisting of a separation protective layer and an overcoating layer.

[0033] In addition, the present invention provides a planar heating element comprising the heating film.

[0034]

[0035] The present invention can provide a heating film that prevents an increase in contact resistance due to a reduction in contact area as the heating electrode is formed in a pattern shape.

[0036] In addition, the present invention can provide a heating film that eliminates the need for a post-processing step to provide heating performance while preventing corrosion and changes over time caused by exposure of the pattern, as the heating electrode is formed in a pattern shape.

[0037] 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 the heating electrode, while preventing localized overheating and thereby preventing damage to the substrate and degradation of heating performance.

[0038] In addition, the present invention can provide a heating film capable of exhibiting uniform heating performance across the entire heating electrode by sufficiently lowering the resistance of the busbar supplying power to maintain a uniform potential difference across the entire heating electrode, thereby preventing a decrease in the potential difference at the heating electrode farther from the power source.

[0039] In addition, by including the heating film, the present invention can provide a planar heating element that is very useful for the transportation industry, such as vehicles, railways, aviation, and helmets, as well as the construction industry.

[0040]

[0041] FIG. 1 is a cross-sectional view of a heating film according to one embodiment of the present invention.

[0042] FIG. 2a is a cross-sectional view of a heating film including a conductive tape among other embodiments of the present invention.

[0043] FIG. 2b is a cross-sectional view of a heating film including a bus bar in another embodiment of the present invention.

[0044] FIGS. 3 and FIGS. 4 are plan views of a heating film according to some embodiments of the present invention connected to an external power source.

[0045] FIG. 5 is a cross-sectional view of a planar heating element according to the present invention.

[0046] FIG. 6 is a schematic diagram illustrating a method for measuring contact resistance for a heating film manufactured according to an embodiment and a comparative example of the present invention.

[0047] FIGS. 7a to 7b are plan and enlarged views illustrating an exemplary pattern of a heating film according to one embodiment of the present invention, and FIG. 7c is an enlarged view illustrating another exemplary pattern of a heating film according to one embodiment of the present invention.

[0048]

[0049] The present invention relates to a heating film and a planar heating element including the same. Since the heating electrode is formed in a patterned shape, the contact area is reduced, thereby preventing an increase in contact resistance and also preventing corrosion and changes over time of the electrode. Furthermore, the present invention provides a heating film and a planar heating element including the same that can exhibit uniform heating performance within a short period of time while preventing localized overheating and exhibiting uniform heating performance across the entire heating electrode.

[0050]

[0051] More specifically, the present invention provides a heating film comprising a substrate layer, a heating electrode formed on the substrate layer and including a pattern, and a transparent electrode laminated between the pattern of the heating electrode and on the upper surface.

[0052] In addition, the present invention provides a planar heating element comprising the heating film.

[0053]

[0054] 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 are intended to illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the aforementioned description; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0055] In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. Throughout the specification, the same reference numerals refer to the same components.

[0056] As used herein, "comprises" and / or "comprising" are used in the sense that they do not exclude the presence or addition of one or more other components, elements, and / or devices other than the mentioned components, elements, and / or devices.

[0057] Spatially relative terms such as "below," "bottom," "lower side," "top," "top surface," and "upper side" may be used to easily describe the relationship between one element or component and another element or component as illustrated in the drawings. Spatially relative terms should be understood as terms that include different directions of the element during use or operation, in addition to the directions illustrated in the drawings. For example, if an element illustrated in the drawings is flipped, an element described as being "below" or "lower side" of another element may be placed on the "top" of that other element. Therefore, the exemplary term "below" may include both the lower and upper directions.

[0058] As used in this specification, the term "connection" includes both indirectly and directly connecting multiple components, and is used to include both physically and electrically connecting components.

[0059]

[0060] Heating Film

[0061] FIG. 1 is a cross-sectional view of a heating film according to one embodiment of the present invention. Referring to FIG. 1, a heating film (10) according to the first embodiment of the present invention comprises a substrate layer (100), a heating electrode (210) formed on the substrate layer (100) and including a pattern, and a transparent electrode (220) formed to cover the entire surface of the heating electrode formed between the pattern of the heating electrode (210) and on the upper surface, preferably.

[0062]

[0063] The above substrate layer (100) performs the role of structurally supporting the heating electrode (210) and maintaining its position, and can use any film-type substrate commonly used in this field without limitation. The above substrate layer (100) may be a transparent substrate capable of transmitting light, and may have flexible characteristics.

[0064]

[0065] In one embodiment, the substrate layer (100) may comprise one or more materials selected from the group consisting of 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.

[0066] The thickness of the substrate layer (100) may be 1 μm to 500 μm, and preferably 5 μm to 75 μm. When the thickness of the substrate layer (100) satisfies the above range, it is desirable because it has the advantage of easy handling during the process while maintaining a stable structure while having transparency and flexible characteristics.

[0067]

[0068] The heating electrode (210) is formed on the substrate layer (100) and includes a pattern.

[0069] The heating electrode (210) may include one or more selected from the group consisting of metal wires and metal meshes, and the metal used for the metal wires and metal meshes is not particularly limited. Examples 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 may be used alone or in a mixture of two or more types.

[0070] The metal mesh described above has a shape in which a plurality of openings are repeated continuously in a regular or irregular manner, and the openings may refer to perforated parts where heating electrodes are not formed, but are not limited thereto.

[0071] The shape of the above opening may be circular, elliptical, or polygonal such as a triangle, square, pentagon, hexagon, heptagon, octagon, etc., and may be of various shapes such as a zigzag shape.

[0072] Meanwhile, the metal wire has a plurality of patterns of various shapes, such as straight or curved lines, in succession, and the shapes are not limited. For example, it may include a plurality of wavy patterns in which unit patterns are repeated.

[0073] Referring to FIGS. 7a to 7c, a plurality of exemplary embodiments of various wave patterns that may be included in the heating electrode (210) of the present invention are shown.

[0074] The above wave pattern may include a first pattern (210-1) in which a unit pattern is repeated in a first direction and a second pattern (210-2) in which a unit pattern is repeated in a direction parallel to the first pattern.

[0075] In the present invention, the wavy pattern refers to a curve in which one or more peaks and valleys are formed alternately, and may have a partially protruding shape or include a modified shape, but is not limited thereto.

[0076] The first pattern (210-1) and the second pattern (210-2) may each have a starting point that is not the same with respect to the first direction.

[0077] In the present invention, the starting point of the wavy pattern refers to the point where the mountain begins among the boundary points of the mountain and the valley, but is not limited thereto.

[0078] In the present invention, the first direction may mean the direction in which the wave pattern proceeds, that is, the direction in which the unit pattern is repeated and extended.

[0079] In the present invention, the second direction refers to a direction perpendicular to the first direction in the plane in which the wave pattern proceeds.

[0080] In addition, in the present invention, the unit pattern refers to one unit of a wave pattern repeated in the first direction, and means the minimum unit that is repeated.

[0081] In the present invention, the first width refers to the width in the first direction with respect to the unit pattern of the first pattern (210-1) and the second pattern (210-2), and the second width refers to the width in the second direction perpendicular to the first direction with respect to the unit pattern of the first pattern (210-1) and the second pattern (210-2).

[0082] The first and second patterns above may be repeated alternately, or the second pattern may be repeated multiple times after the first pattern is repeated multiple times, and the repetition rate of each pattern is not particularly limited.

[0083] Meanwhile, referring to FIG. 7c, the wave pattern includes a first pattern (210-1) in which a unit pattern is repeated in a first direction and a third pattern (210-3) in which a unit pattern is repeated in another direction not parallel to the first direction, and may include a plurality of geometric shapes formed by the first pattern and the third pattern intersecting each other.

[0084] The other direction mentioned above is the direction in which the third pattern (210-3) proceeds, and the angle between the tangents of each pattern at the point where the first pattern (210-1) and the third pattern (210-3) intersect may be greater than 0° and less than or equal to 90°.

[0085] As such, the heating electrode of the present invention may include various wave patterns, and in this case, the starburst phenomenon caused by the pattern can be prevented, thereby ensuring excellent visibility.

[0086] The heating electrode (210) may include a pattern, and the pattern may have a line width of 0.5 μm to 30 μm. It is preferable that the line width of the heating electrode satisfies the above range, as this allows for sufficient heating performance while reducing the visibility of the electrode.

[0087] The heating electrode (210) may have a height of 0.1 μm to 1 μm, and preferably 0.3 μm to 0.8 μm. When the heating electrode (210) satisfies the above height, there is an advantage in that the taper of the heating electrode (210) can be appropriately adjusted.

[0088] Accordingly, this is desirable as it can reduce the defect rate in the heating film manufacturing process and improve ESD (electrostatic discharge) durability, thereby increasing product reliability.

[0089] In addition, the space gap between the heating electrode (210) patterns is preferably 30㎛ to 2500㎛ in terms of visibility.

[0090] In the present specification, the line width, thickness, average spacing of the wiring, etc. may be the average value obtained by measuring 10 or more random target points using a scanning electron microscope (SEM), etc.

[0091] The taper of the heating electrode (210) may be a net taper, and preferably may have an angle of 20° to 50°. As the thickness of the heating electrode (210) increases, the taper angle may deviate from an appropriate range.

[0092] In addition, if a reverse taper or a sharp taper is formed, there may be problems such as unintended short circuits in the electrical connection between the upper and lower layers or the formation of microbubbles between each layer during the subsequent stacking process.

[0093] The heating electrode (210) can be manufactured through a manufacturing method of a sputtering process and a plating process.

[0094]

[0095] The heating electrode (210) may further include a blackening layer (250) on one or both sides.

[0096] Referring to the enlarged view of the heating electrode (210) illustrated in FIG. 1, the heating electrode (210) may further include a blackening layer (250) on both sides, and although not illustrated, the heating electrode (210) may also include a blackening layer on only one side.

[0097] If the heating electrode (210) includes a material that reflects light in the visible light region, such as metal, problems such as glare may occur due to issues with visibility that are easily visible to the human eye and high reflectivity to external light.

[0098] Accordingly, the heating film (10) of the present invention may further include a blackening layer (250) on one or both sides of the heating electrode (210), thereby reducing the reflectivity of the heating electrode (210) and preventing problems such as poor visibility and glare. When the blackening layer (250) is formed on both sides of the heating electrode (210), problems regarding poor visibility and glare inside and outside the heating film can be improved.

[0099] In addition, by forming the blackened layer (250) as described above, the problem of contact resistance occurring due to surface oxidation of the heating electrode (210) can be improved, thereby improving the reliability of the electrode.

[0100] The above blackened layer (250) can be formed, for example, using a composition for forming a blackened layer.

[0101] The composition for forming the blackening layer may include one or more 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 may be formed by including an oxide containing the metal, and examples of the oxide containing the metal include Al2O3, Fe2O3, TiO2, MnO3, Cr2O3, Cu2O, CuO, Cu2O3, ZnO, NiO, etc.

[0102] The above blackened layer (250) may be deposited through a deposition process such as sputtering or formed by electroplating, but is not limited thereto.

[0103] When the heating film (10) of the present invention includes a blackening layer (250), the blackening layer (250) may have a thickness of 0.01 μm to 1 μm in order to prevent problems such as visibility and glare of the heating electrode while not reducing heating performance.

[0104] The heating film (10) of the present invention includes a transparent electrode (220) formed to cover the entire surface where the heating electrode is formed, preferably laminated between the patterns of the heating electrode (210) and on the upper surface.

[0105] The transparent electrode (220) may be one or more selected from the group consisting of carbon nanotubes (CNT), graphene, silver nanowires (AgNW), polypyrrole, polythiophene, polyacetylene, PEDOT, polyaniline, indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), fluorine tin oxide (FTO), and zinc oxide (ZnO), and preferably may be indium tin oxide (ITO).

[0106] The above transparent electrode (220) is formed on the heating electrode (210), and can be formed in a manner that completely covers the heating electrode (210) formed on the substrate layer (100) by filling not only the upper surface of the pattern forming the heating electrode but also the space between the patterns.

[0107] By covering the entire heating electrode (210) with the transparent electrode (220), there is no exposed part of the heating electrode, and therefore, changes over time and corrosion do not occur.

[0108] In addition, when a conductive tape and / or flexible circuit board (FPCB) are laminated, a transparent electrode (220) also comes into contact with the heating electrode (210), so the contact area with the conductive tape and / or flexible circuit board (FPCB) increases, and thus the contact resistance is lowered.

[0109] Therefore, it is possible to prevent a decrease in heat generation performance or localized overheating caused by an increase in contact resistance.

[0110] The transparent electrode (220) may have a height of 100 Å to 2000 Å from the upper surface of the heating electrode (210), and preferably 150 Å to 1100 Å.

[0111] The heating film of the present invention may have a total light transmittance of 80% or more. When the transparent electrode (220) covers the entire area where the heating electrode (210) is placed, the transmittance may decrease slightly. However, in the heating film of the present invention, a material with excellent transmittance is applied as the transparent electrode (220), and the thickness of the transparent electrode is formed such that the height from the upper surface of the heating electrode (210) is in the range of 100 Å to 2000 Å as described above, so that the transmittance of the heating electrode is not reduced to a problematic level.

[0112] The above transparent electrode (220) can be manufactured through a manufacturing method of a deposition process such as sputtering.

[0113] The heating film of the present invention, by forming a transparent electrode (220) as described above, may have a resistance difference of 2Ω or less, preferably 1Ω or less, before and after attaching a conductive tape, and can effectively prevent the contact resistance of the heating film from rising.

[0114] In addition, the heating film of the present invention has a negligible difference in resistance before and after the attachment of the conductive tape as described above, so the resistance can be maintained at a level of 1Ω to 20Ω, preferably 1Ω to 6Ω.

[0115]

[0116] FIG. 2 is a cross-sectional view of a heating film including a conductive tape (350) or a bus bar (300) in another embodiment of the present invention.

[0117] Referring to FIG. 2a, the heating film of the present invention may be in the form in which a conductive tape (350) is attached to a transparent electrode (220) formed by stacking between and on the upper surface of a heating electrode including the pattern to cover the pattern. A conductive substrate, such as an FPCB, may be further stacked on the conductive tape (350).

[0118] Additionally, referring to FIG. 2b, in one embodiment of the present invention, the heating film of the present invention may include a bus bar (300) connected to both ends of the heating electrode (210).

[0119] In this case, the transparent electrode (220) may be formed by covering the upper surface and side surface of the bus bar (300).

[0120] Although not directly illustrated in FIG. 2b, the blackened layer (250) included in the heating electrode (210) may be formed extending to the upper surface of the bus bar (300).

[0121]

[0122] Referring to FIG. 2a above, the transparent electrode (220) has a conductive tape (350) attached to a part of its upper surface, specifically to both ends of the transparent electrode, so that current can flow and heat can be generated through a physically direct connection, and the conductive tape (350) provides a passage for current (or electrons) supplied from an external power source to travel.

[0123] Therefore, in the case of the present invention, the contact area with the electrode becomes larger than when the conductive tape (350) is directly attached to the upper surface of the patterned heating electrode (210).

[0124] Accordingly, the heating film of the present invention has a lower contact resistance as described above and can maintain an appropriate resistance level before and after attachment of the conductive tape (350).

[0125] The above conductive tape (350) can be used without limitation as long as it is a material known in the art, for example, it can be formed into a product in which a conductive adhesive is applied to a conductive fiber, metal foil, etc.

[0126]

[0127] The width of the conductive tape (350) may be 50 mm or less, but is not limited thereto, and may be appropriately adjusted according to the shape of the means of transport, device, or building to which the heating film is applied. For example, if the diagonal width of the heating film is 20 inches or less, the width of the conductive tape (350) may be 1 mm to 6 mm, and if the diagonal width of the heating film is 20 inches or more, the width of the conductive tape (350) may be 2 mm to 50 mm. If the width of the conductive tape (350) satisfies the above range, there is an advantage in that current (electrons) can be stably supplied to the heating electrode (210) without a problem of visibility. If the width of the conductive tape (350) exceeds the above range, the surface resistance may decrease as the area through which current flows increases, but there may be a problem in that the visibility of the conductive tape (350) increases, making it difficult to apply to an actual product.

[0128] Additionally, a conductive substrate (not shown) may be further laminated on the conductive tape (350), and the conductive substrate may be any known circuit board that can be electrically connected, such as a flexible circuit board (FPCB) or a printed circuit board (PCB). In particular, the FPCB is a substrate in which a circuit is formed on a flexible film, and can be formed using a heat-resistant plastic film such as polyimide (PI), which is a flexible material, and copper foil.

[0129] In addition to this, any conductive substrate formed of a material capable of achieving the intended purpose may be used without limitation.

[0130]

[0131] Referring to FIG. 2b, the heating electrode (210) has both ends physically directly connected to the bus bar (300), so that current flows between the positive and negative electrodes and generates heat. In order to ensure uniform heating occurs throughout the heating electrode (210), a pair of bus bars (300) facing the heating electrode (210) may be formed to be parallel to each other, but are not limited thereto.

[0132] The above busbar (300) provides a passage through which current (or electrons) supplied from an external power source travels.

[0133] The above busbar (300) may be formed on the same layer as the heating electrode (210) using the same material. For example, in a conventional heating film, a heating electrode is formed first on a substrate, and a busbar is formed as a separate layer on top of both ends of the formed heating electrode. However, if the heating electrode and the busbar are formed on different layers and connected in this way, contact resistance occurs between the busbar and the heating electrode, and the heating performance may be degraded due to the increase in resistance resulting therefrom. In addition, when the heating film is bonded to a cover glass, etc. through a heat fusion or laminating process, an electrical short circuit may occur between the upper layer (busbar) and the heating electrode due to the tapered step difference of the patterned heating electrode, and consequently, a problem may arise in which the overall resistance increases.

[0134] Additionally, the heating electrode (210) and the bus bar (300) may be formed integrally in the same process step. As described above, if the heating electrode (210) and the bus bar (300) are formed in different layers in different process steps and connected, the resistance may increase due to increased contact resistance between the upper and lower layers and electrical short circuits. Furthermore, if the heating electrode (210) and the bus bar (300) are formed in different process steps and connected in the same layer, problems may arise such as localized overheating due to uneven contact area or poor contact, or uneven heating performance.

[0135] The thickness of the above bus bar (300) may be 0.1㎛ to 1㎛, and preferably 0.3㎛ to 0.8㎛. Satisfying the above thickness range has the advantage of allowing the taper to be appropriately adjusted, and is therefore desirable as it can reduce the defect rate in the heating film manufacturing process and improve ESD (electrostatic discharge) durability, thereby increasing the reliability of the product.

[0136] The width of the busbar (300) may be 50 mm or less, independently, but is not limited thereto, and may be appropriately adjusted according to the shape of the means of transport, device, or building to which the heating film is applied. For example, if the diagonal width of the heating film is 20 inches or less, the width of the busbar (300) may be 1 mm to 6 mm, and if the diagonal width of the heating film is more than 20 inches, the width of the busbar (300) may be 2 mm to 50 mm. If the width of the busbar (300) satisfies the above range, there is an advantage in that current (electrons) can be stably supplied to the heating electrode (210) without a problem of visibility. If the width of the busbar (300) exceeds the above range, the surface resistance may decrease as the area through which current flows increases, but there may be a problem in that the visibility of the busbar increases, making it difficult to apply to an actual product.

[0137] The above busbar may include multiple layers, although not illustrated.

[0138] When forming multiple layers of busbars, they can be formed using a conductive paste, and when a blackening layer is laminated on the heating electrode (210) or when a blackening layer and a capping layer are formed, a blackening layer and / or a capping layer are laminated on the busbar (300) formed integrally with the heating electrode (210) in the same way, and multiple busbars can be formed on the laminated blackening layer or capping layer.

[0139]

[0140] The conductive paste may comprise one or more 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 achieving low sheet resistance, it is preferable to include silver (Ag) or gold (Au), and most preferable to include silver (Ag).

[0141] In the case where the heating film of the present invention includes a bus bar (300), a transparent electrode (220) may be formed by covering not only the pattern between and the upper surface of the heating electrode (210), but also the upper surface and side surface of the bus bar (300).

[0142] In this case, current can be allowed to flow by connecting to an external power source (40) on the transparent electrode (220) corresponding to the position of the bus bar (300).

[0143] FIGS. 3 and 4 are plan views of a heating film (10) according to some embodiment of the present invention connected to an external power source (40).

[0144] As shown in FIG. 3, the external power source (40) may be connected to both ends of the conductive tape (350) or busbar (300). When the heating film of the present invention is applied to a means of transport or a device, etc., by connecting the external power source (40) to the ends of the conductive tape (350) or busbar (300), the wiring from the external power source (40) to the conductive tape (350) or busbar (300) can be connected over the shortest distance, thereby increasing design efficiency.

[0145] As shown in FIG. 4, the external power source (40) may be connected to the center of both sides of the conductive tape (350) or busbar (300). When the external power source (40) is connected to the center of the conductive tape (350) or busbar (300), the longest path for the current (electron) to travel can be shortened compared to when the external power source (40) is connected to the end of the conductive tape (350) or busbar (300). Accordingly, it is easy to achieve equipotential across the entire heating electrode (210), which has the advantage of providing more uniform heating performance.

[0146] The conductive tape (350) may have a structure in which a conductive substrate (not shown) is laminated, and the conductive substrate may be, for example, a flexible circuit board (FPCB).

[0147] The above busbar (300) may form a straight line and the heating electrode (210) may have a rectangular shape, but is not limited thereto and may have a shape suitable for the shape of the means of transport, device, or building to which the heating film (10) is applied.

[0148] Meanwhile, as described above, the heating film according to the present invention may include a plurality of layers of busbars (300), and accordingly, the surface resistance over the entire busbar (300) can be sufficiently reduced.

[0149] Therefore, even when an external power source (40) is connected to the end of the bus bar (300), the potential difference can be reduced across the entire heating electrode (210), and accordingly, uniform heating performance can be exhibited.

[0150] The heating film of the present invention may further include one or more selected from the group consisting of a separation protection layer and an overcoating layer, although not illustrated.

[0151] The heating film of the present invention may further include a separation protective layer between the substrate layer (100) and the heating electrode (210) to improve the adhesion between them. The separation protective layer may be formed using an adhesive and is preferably formed with appropriate adhesion to prevent peeling, bubbles, etc., from occurring when handling the heating film, while simultaneously possessing transparency and thermal stability.

[0152] The adhesive mentioned above may be any adhesive used in the field without limitation, and for example, a photocurable adhesive may be used. The photocurable adhesive is one that cross-links and cures upon receiving active energy rays such as ultraviolet (UV) rays or electron beams (EB) to exhibit strong adhesive strength, and examples include polyester resins, polyether resins, polyurethane resins, epoxy resins, polyacrylic resins, silicone resins, etc.

[0153] When the heating film of the present invention includes a separation protective layer, the separation protective layer may have a thickness of 0.1 μm to 10 μm, preferably 1 μm to 5 μm, in order to secure sufficient adhesion and minimize the thickness.

[0154]

[0155] The heating film of the present invention may include an overcoating layer on the uppermost part of the heating film to prevent damage to the heating electrode (210) and further improve mechanical durability.

[0156] The above overcoating layer may include one or more 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.

[0157] When the heating film of the present invention includes an overcoating layer, the overcoating layer may have a thickness of 0.1 μm to 10 μm, preferably 1 μm to 5 μm, in order to prevent cracks caused by bending, etc. while ensuring sufficient mechanical durability.

[0158]

[0159] Method for manufacturing a heating film

[0160] The present invention has the scope of a method for manufacturing the heating film described above, and, as an example, includes a method for manufacturing a heating film such that a transparent electrode is laminated between the patterns of heating electrodes and on the upper surface.

[0161] Specifically, the method for manufacturing a heating film of the present invention may include the steps of: preparing a substrate layer; forming a heating electrode including a pattern on the substrate layer; and laminating a transparent electrode between the patterns and on the upper surface of the heating electrode.

[0162] The method for manufacturing the heating film of the present invention includes, without limitation, the contents described in the above-mentioned <Heating Film> section.

[0163]

[0164] Surface heating element

[0165] FIG. 5 is a cross-sectional view of a planar heating element according to the present invention.

[0166] Referring to FIG. 5, the planar heating element of the present invention may include a heating film (10), an external member adhesive layer (20), and an external member (30).

[0167] The above external member adhesive layer (20) is for bonding the heating film (10) and the external member (30), and may be formed using EVB (Ethyl vinyl benzene), PVA (Polyvinyl alcohol), EVA (Ethylene vinyl acetate), PU (Polyurethane), etc.

[0168] The above-mentioned external member (30) may be a glass or plastic substrate, and the same content regarding the substrate layer (100) described above may be applied. As the heating film (10) of the present invention is applied to the above-mentioned external member (30) as a target for fogging or frost formation, the fogging or frost formed on the inside and outside of the external member (30) can be removed in a short period of time.

[0169] The planar heating element of the present invention may be applied in various fields such as the construction industry (e.g., building windows and doors); means of transportation (e.g., vehicles, railways, or aircraft); helmets; and smart glasses, but is not limited thereto.

[0170]

[0171] The present invention will be explained in more detail below using examples and comparative examples. However, the following examples are intended to illustrate the present invention, and the present invention is not limited by the following examples and may be modified and changed in various ways.

[0172]

[0173] < Examples and Comparative Examples: Preparation of Heating Films >

[0174] Example 1: A heating film having a structure in which a transparent electrode covers both the upper surface and the space between the heating electrode patterns.

[0175] A blackened layer was formed by sputtering copper II oxide (CuO) to a thickness of 600 Å (0.06 μm) on a 150 mm x 150 mm glass substrate (0.5 T Soda lime Eagle XG Glass, Corning), and a heating electrode was formed by sputtering a copper layer (Cu) with a thickness of 6000 Å (0.6 μm) on the blackened layer.

[0176] A blackened layer was formed by sputtering copper II oxide (CuO) to a thickness of 600 Å (0.06 μm) on the copper layer (Cu) which is the heating electrode.

[0177] Subsequently, a heating electrode including a pattern was formed by forming a mesh pattern on the heating electrode having the blackened layer stacked thereon through photolithography and etching processes.

[0178] The width of the mesh of the heating electrode is 4.5㎛, the height is 0.75㎛ (7500Å), and the space gap between patterns is 465㎛.

[0179] A transparent electrode was formed by sputtering IZO as a transparent electrode material so as to completely cover the pattern of the heating electrode on the pattern of the heating electrode. At this time, the height of the transparent electrode from the upper surface of the heating electrode is 150 Å.

[0180]

[0181] Comparative Example 1: A heating film having a structure in which a transparent electrode covers only the upper surface of a heating electrode pattern

[0182] A blackened layer was formed by sputtering copper II oxide (CuO) to a thickness of 600 Å (0.06 μm) on a 150 mm x 150 mm glass substrate (0.5 T Soda lime Eagle XG Glass, Corning), and a heating electrode was formed by sputtering a copper layer (Cu) with a thickness of 6000 Å (0.6 μm) on the blackened layer.

[0183] Copper II oxide (CuO) was sputtered to a thickness of 600 Å (0.06 μm) on the copper layer (Cu) which is the heating electrode to form a blackened layer, and IZO was sputtered to a thickness of 150 Å (0.015 μm) as a transparent electrode on the blackened layer.

[0184] Subsequently, a mesh pattern was formed on the heating electrode through photolithography and etching processes, and the line width and thickness of the mesh pattern and the spacing between patterns were formed in the same way as in Example 1.

[0185]

[0186] < Experimental Example >

[0187] (1) Contact resistance evaluation

[0188] For a heating film (150 mm X 50 mm) prepared according to Example 1 and Comparative Example 1, as shown in FIG. 6, a conductive tape (350, 2200F-70, manufactured by Alkynes Co., Ltd.) with a width of 15 mm and a thickness of 83 μm was laminated on both ends of the upper surface of the patterned heating electrode (210) and the transparent electrode (220), and an FPCB (PI thickness 25 μm and Cu thickness 18 μm) with a width of 15 mm was bonded onto the conductive tape. The contact resistance before and after bonding was measured using a multimeter (fluke 87V) as shown in FIG. 6, and the results are shown in Table 1 below.

[0189]

[0190] (2) Corrosiveness evaluation

[0191] For the heating films (150mm X 50mm) prepared according to Example 1 and Comparative Example 1, when the resistance was evaluated after exposing the electrodes to room temperature air for more than one week, the resistance of the heating film prepared according to Example 1 did not change, but the resistance of the heating film prepared according to Comparative Example 1 increased.

[0192] Corrosiveness Assessment Criteria

[0193] ○: No increase in resistance after being left for one week in an environment of 85℃ temperature and 85%RH humidity.

[0194] ×: Increase in resistance observed after being left for one week in an environment of 85℃ and 85%RH humidity

[0195]

[0196] (3) Transmittance measurement

[0197] For the heating films of the examples and comparative examples, the total light transmittance (Tt) was measured using a haze meter HM-150N (Murakami Co., Ltd.), and the results are shown in Table 1 below.

[0198] Classification Contact Resistance (Ω) Corrosiveness Transmittance (%) Before Bonding After Bonding Example 1 10.7 10.5 × 88.5 Comparative Example 1 10.7 131.2 × 90.1

[0199] Referring to Table 1 above, it can be confirmed that the heating electrode according to Example 1 of the present invention does not have an excessive increase in contact resistance because the contact area is not reduced when bonding the conductive tape and FPCB by covering the pattern with a transparent electrode. In other words, it can be seen that the contact resistance of the heating film according to the present invention is stably maintained before and after bonding the conductive tape. Furthermore, it can be confirmed that corrosion is prevented because the heating electrode according to Example 1 of the present invention is not exposed, and that an appropriate transmittance can be provided by ensuring an overall light transmittance of 80% or more even though the transparent electrode layer is formed on the front surface.

[0200] In contrast, in Comparative Example 1, where a transparent electrode material is formed only on the upper surface of the pattern, it can be seen that the contact resistance has increased excessively and the corrosiveness is also very poor.

[0201]

[0202] The present invention can provide a heating film that prevents an increase in contact resistance due to a reduction in contact area as the heating electrode is formed in a pattern shape.

Claims

1. Record layer; A heating electrode formed on the above substrate layer and including a pattern; and A heating film comprising: a transparent electrode laminated between the patterns of the heating electrodes and on the upper surface.

2. In Claim 1, A heating film in which the heating electrode is formed by including at least one selected from silver (Ag), gold (Au), aluminum (Al), copper (Cu), molybdenum (Mo), nickel (Ni), zinc (Zn), tungsten (W), titanium (Ti), tellurium (Te), chromium (Cr), and alloys containing at least one of these.

3. In Claim 1, A heating film wherein the transparent electrode is formed by including one or more selected from the group consisting of carbon nanotubes (CNT), graphene, silver nanowires (AgNW), polypyrrole, polythiophene, polyacetylene, PEDOT, polyaniline, indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), fluorine tin oxide (FTO), and zinc oxide (ZnO).

4. In Claim 1, The above heating film is a heating film having a resistance of 1Ω to 20Ω.

5. In Claim 1, The above heating film is a heating film in which the difference in resistance before and after attaching a conductive tape to one surface of a transparent electrode is 2Ω or less.

6. In Claim 1, The heating electrode comprises one or more types selected from the group consisting of metal wire and metal mesh, and is a heating film.

7. In Claim 6, The above metal wire is a heating film comprising a plurality of wavy patterns.

8. In Claim 1, The heating electrode is a heating film comprising a pattern having a line width of 0.5 μm to 30 μm.

9. In Claim 1, The heating electrode is a heating film having a spacing distance between patterns of 30㎛ to 2500㎛.

10. In Claim 1, The above transparent electrode is a heating film having a height from the upper surface of the heating electrode of 100 Å to 2000 Å.

11. In Claim 1, The above heating film is a heating film having a total light transmittance of 80% or more.

12. In Claim 1, A heating film comprising a conductive tape attached to one surface of the above-mentioned transparent electrode.

13. In Claim 1, A heating film comprising a busbar connected to both ends of the heating electrode.

14. In Claim 13, A heating film in which the heating electrode and busbar are formed on the same layer of the same material.

15. In Claim 13, A heating film in which the heating electrode and busbar are integrally formed in the same process step.

16. In Claim 1, The heating electrode above is a heating film that further includes a blackening layer on one or both sides.

17. In Claim 1, The heating film further comprises one or more types selected from the group consisting of a separation protective layer and an overcoating layer.

18. A planar heating element comprising the heating film of claim 1.

Images