Heat-generating clad metal material having graphene heating layer and cookware using the same

Abstract

The present invention relates to a heating type clad metal material having a graphene heating layer and a cooking utensil using the same, and more specifically, to a clad metal material in which a graphene heating layer that generates resistance heat by electrical current is laminated in multiple layers together with a metal layer, and an insulating layer is interposed between the graphene heating layer and the metal layer to form an integrated clad metal material, a cooking utensil in the form of a frying pan, wok, or pot formed by molding the same, and a detachable handle that provides an electrical connection to the graphene heating layer of the cooking utensil.

Description

Technology Field

[0001] The present invention relates to a heating type clad metal material having a graphene heating layer and a cooking utensil using the same, and more specifically, to a clad metal material in which a graphene heating layer that generates resistance heat by electrical current is laminated in multiple layers together with a metal layer, and an insulating layer is interposed between the graphene heating layer and the metal layer to form an integrated clad metal material, a cooking utensil in the form of a frying pan, wok, or pot formed by molding the same, and a detachable handle that provides an electrical connection to the graphene heating layer of the cooking utensil. Background Technology

[0002] Metal materials used in cookware have been widely provided in a so-called clad form, consisting of multiple layers of metal bonded together to ensure both heat transfer characteristics and durability. Considering that temperature variations between the bottom and sides are prone to occur when the cooking surface is composed solely of metals with slow heat transfer, these multilayer metal materials have evolved to diffuse heat from a heat source across the entire surface by placing a metal with fast heat transfer as a diffusion core and positioning other metals on either side. However, since this method relies on external heat sources such as gas, induction, and air fryers to raise the temperature of the cooking surface, there has been a steady interest in configurations where the cookware itself possesses a heat source.

[0003] Amid ongoing attempts to introduce self-heating materials into cooking appliances through electric current, graphene has garnered attention as a heat source material due to its ability to generate resistive heat through electric current, as well as its excellent mechanical strength and moldability. However, when graphene is introduced into metal materials, if it is incorporated in a form where it is directly bonded to the metal, the pattern of heat transfer at the interface may change; consequently, consideration has been required regarding the layer composition to ensure that heat is fully transferred to the cooking surface. Furthermore, simply adding another layer responsible for the heating function to a multilayer metal material makes it difficult to achieve a balance between heat transfer and the suppression of overheating. Therefore, determining how to establish the relationship between the graphene heating layer and the adjacent metal layer has become an important consideration.

[0004] Meanwhile, heating cookware requires a connection structure to conduct electricity to the heating layer on the cooking surface side. However, if such an electrical connection structure is complexly configured within the main body of the cookware, cleaning and handling become cumbersome and commercialization may not be easy. Consequently, there has been a demand for a structure that can simply draw out the electrical connection and control the conduction. Furthermore, during the process of forming a metal plate into a frying pan, wok, or pot, a very thin heating layer can be affected by forming stress in curved sections with a large forming depth. Therefore, there has been ongoing research into a layer composition that is compatible with ensuring the heating layer maintains its function without interruption throughout the entire cookware even after forming. The problem to be solved

[0005] The present invention may aim to provide a heating-type clad metal material and a cooking utensil using the same, wherein a graphene heating layer that generates resistive heat through electric current is incorporated into a metal material, and the heat generated is efficiently transferred to the cooking surface while suppressing overheating.

[0006] The present invention can achieve the objective of avoiding the inhibition of heat transfer at the interface when a graphene heating layer is directly bonded and combined with a metal layer, and establishing the relationship between the graphene heating layer and the metal layer as a layered structure to achieve both heat transfer and suppression of overheating.

[0007] The present invention can achieve the objective of not merely adding a layer responsible for the heating function, but also ensuring that the cooking surface is heated uniformly while suppressing localized overheating and sticking of the cooking surface.

[0008] The present invention can achieve the objective of simplifying the electrical structure of the cooking appliance body without complexly configuring a connection structure for conducting electricity to a graphene heating layer in the cooking appliance body.

[0009] The present invention can achieve the objective of ensuring that the graphene heating layer maintains a heating function continuously and without interruption throughout the entire cooking appliance, even during the process of forming a metal plate into the shape of a cooking appliance including a curved surface.

[0010] The problems that this disclosure 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. means of solving the problem

[0011] According to one aspect of the present invention, a heating clad metal material may be provided, comprising: a metal layer; a graphene heating layer that generates resistive heat by electrical conduction; and an insulating layer interposed between the graphene heating layer and the metal layer to block direct contact between the graphene heating layer and the metal layer, wherein the metal layer, the insulating layer, and the graphene heating layer are laminated in a plurality of layers and integrated.

[0012] For example, a heat-generating clad metal material may be provided, further comprising an additional metal layer laminated on one side in the direction in which the plurality of layers are laminated.

[0013] For example, a heat-generating clad metal material may be provided, further comprising a heat transfer accelerating metal layer laminated on the cooking surface side of the plurality of layers above to accelerate heat transfer to the cooking surface.

[0014] For example, a heat-generating clad metal material may be provided, wherein the metal layer comprises a plurality of metal layers, and the plurality of metal layers include a heat-diffusing metal layer that has faster heat transfer than the remaining metal layers and is disposed inward in the thickness direction of the plurality of layers to diffuse heat.

[0015] For example, the heat-diffusing metal layer may be provided with a heat-generating clad metal material interposed between the cooking surface side metal layer disposed on the cooking surface side and the insulation layer.

[0016] For example, a heating clad metal material may be provided, wherein the metal layer comprises an outer metal layer disposed on the opposite side of the cooking surface with respect to the graphene heating layer among the plurality of layers, and the outer metal layer is a magnetic metal layer.

[0017] For example, a heating clad metal material may be provided, further comprising an insulating protective layer disposed on the opposite side of the two sides of the graphene heating layer where the insulating layer is interposed, and which electrically insulates the graphene heating layer from an adjacent metal layer.

[0018] For example, the plurality of layers are stacked in the order of a cooking surface side metal layer, a heat diffusion metal layer, the insulating layer, the graphene heating layer, an insulating protective layer, and an outer metal layer from the cooking surface side, and the graphene heating layer has a cooking surface side in contact with the insulating layer and an opposite side in contact with the insulating protective layer, so that both sides are electrically insulated from the adjacent metal layer, and a heating clad metal material may be provided.

[0019] For example, the above-mentioned insulating layer may be a dielectric interlayer having both electrical insulation and thermal conductivity, which electrically insulates the graphene heating layer and the metal layer while transferring the heat from the graphene heating layer to the cooking surface side, and may be provided as a heating clad metal material.

[0020] For example, a heating clad metal material may be provided in which the dielectric interlayer is interposed on the cooking surface side of the graphene heating layer, electrically insulating the graphene heating layer from the cooking surface side metal layer while thermally bonding the graphene heating layer and the cooking surface side metal layer.

[0021] For example, a heating clad metal material may be provided, wherein the thickness of the dielectric interlayer is 10 to 200 micrometers.

[0022] For example, a heating clad metal material may be provided, wherein the thickness of the dielectric interlayer is 25 to 100 micrometers.

[0023] For example, a heating clad metal material may be provided, wherein the thickness of the dielectric interlayer is 40 to 60 micrometers.

[0024] For example, a heating clad metal material may be provided in which the thermal conductivity of the dielectric interlayer is 5 to 15 W / m·K.

[0025] For example, the dielectric interlayer may be provided with a heating clad metal material having a thickness greater than or equal to a lower thickness limit having an dielectric breakdown voltage greater than or equal to the feed voltage applied to the graphene heating layer.

[0026] For example, a heating clad metal material may be provided, wherein the graphene heating layer has an exposed end having opposing ends that are exposed and extended to the edges of the plurality of layers, and a power supply electrode (busbar) formed at the exposed end and electrically connected to the graphene heating layer; and an insulating sleeve that wraps the exposed end and insulates the power supply electrode (busbar) from an adjacent metal layer.

[0027] For example, a heating clad metal material may be provided in which the exposed ends are formed at opposite ends of the graphene heating layer, and the power supply electrodes (busbars) are disposed at the ends to conduct current across the entire surface of the graphene heating layer.

[0028] For example, a heating clad metal material may be provided in which the above-mentioned power supply electrode (busbar) is electrically connected only to the graphene heating layer and is insulated from an adjacent metal layer by the insulating sleeve and drawn out toward the edge of the plurality of layers.

[0029] For example, a heating clad metal material may be provided, further comprising an anchoring protrusion formed at the interface between the insulating layer and the graphene heating layer to mechanically engage the graphene heating layer with the insulating layer.

[0030] For example, a heating clad metal material may be provided, further comprising an adhesive primer layer interposed at the interface between the insulating layer and the graphene heating layer to mediate adhesion between the graphene heating layer and the insulating layer.

[0031] For example, the heating clad metal material may be provided in such a way that the heating clad metal material is a molded body including a curved portion, and the graphene heating layer is continuously engaged with the anchoring irregularities throughout the entire molded body including the curved portion without interruption.

[0032] For example, a heating clad metal material may be provided in which the thickness of the graphene heating layer in the curved portion is 50% or more of the thickness of the graphene heating layer in the flat portion.

[0033] For example, a heating clad metal material may be provided in which the thickness of the graphene heating layer in the curved portion is 70% or more of the thickness of the graphene heating layer in the flat portion.

[0034] For example, a heating clad metal material may be provided in which the thickness of the graphene heating layer in the curved portion is 85% or more of the thickness of the graphene heating layer in the flat portion.

[0035] For example, a heating clad metal material may be provided, wherein the graphene heating layer has a strain-relief shape formed on the curved portion to disperse forming stress and thermal expansion stress, and the strain-relief shape includes at least one of a split portion, a wrinkle portion, and a recess portion formed on the graphene heating layer.

[0036] For example, a heating clad metal material may be provided, further comprising a first feed electrode (busbar) and a second feed electrode (busbar) spaced apart from each other in the graphene heating layer, wherein the graphene heating layer comprises a plurality of segments divided along a feed direction in which current flows between the first feed electrode (busbar) and the second feed electrode (busbar), and each of the plurality of segments is connected in parallel to the first feed electrode (busbar) and the second feed electrode (busbar).

[0037] For example, a heating clad metal material may be provided, wherein each of the plurality of segments has a stripe shape extended along the power supply direction.

[0038] For example, a heating clad metal material may be provided in which the plurality of segments are in the shape of a plurality of tiles arranged two-dimensionally along the plane of the graphene heating layer.

[0039] For example, a heating clad metal material may be provided, which further includes a complete insulation gap formed at the boundary between the plurality of segments to block in-plane current flow between adjacent segments, wherein the complete insulation gap is arranged in an interdigital shape or a zigzag shape so that the heating zones of adjacent segments interlock with each other in a projection onto the cooking surface.

[0040] For example, a heating clad metal material may be provided in which the graphene heating layer is continuous without interruption within each of the plurality of segments and is electrically separated only from one another by the complete insulation gap.

[0041] For example, a heating clad metal material may be provided, which further includes a self-regulating ballast that is arranged in series with respect to the first feed electrode (bus bar) or the second feed electrode (bus bar) of each of the plurality of segments, and whose resistance increases as the temperature of the segment rises to reduce the current flowing through the segment, wherein the self-regulating ballast is a ballast stripe in which the metal layer among the plurality of layers is patterned into a long and narrow fine parallel stripe.

[0042] For example, the ballast stripe may be provided with a heat-generating clad metal material having a length-to-width ratio of 5 to 100.

[0043] For example, the self-regulating ballast may be provided with a heating clad metal material having a constant resistance temperature coefficient characteristic in which resistance increases continuously with temperature rise without Curie transition, and a resistance increase rate of 10 to 60% per 100°C of temperature rise.

[0044] For example, a heating clad metal material may be provided, further comprising a self-regulating ballast arranged in series with respect to the first feed electrode (bus bar) or the second feed electrode (bus bar) of each of the plurality of segments and including a constant temperature coefficient characteristic element, wherein the effective transition temperature range of the constant temperature coefficient characteristic element is 200 to 320°C.

[0045] For example, a heat-generating clad metal material may be provided in which the effective transition temperature range of the above-mentioned constant temperature coefficient characteristic element is 230 to 280°C.

[0046] For example, a heat-generating clad metal material may be provided in which the effective transition temperature range of the above-mentioned constant temperature coefficient characteristic element is 250 to 260°C.

[0047] For example, a heating clad metal material may be provided, further comprising a compensation conductive network composited in the graphene heating layer, wherein the compensation conductive network is a conductive fiber network arranged such that contact points between fibers are rearranged upon elongation to increase parallel conduction paths, and is composited in the graphene heating layer at a density near a conduction threshold that exhibits a sheet resistance matching the graphene heating layer in a flat portion, and is confined and disposed within each of the plurality of segments.

[0048] For example, a heating clad metal material may be provided in which a complete insulation gap formed at the boundary between the plurality of segments is cut off by penetrating the graphene heating layer and the compensation conductive network together, thereby preventing the compensation conductive network from being conductively connected to an adjacent segment beyond the complete insulation gap.

[0049] For example, a heating clad metal material may be provided in which the graphene heating layer is supported on both sides by the insulating layer and an insulating protective layer disposed on the opposite side of the insulating layer, and the compensating conductive network is composited with the graphene heating layer and supported by a continuous support surface formed by the insulating layer and the insulating protective layer.

[0050] For example, the above-mentioned compensation challenge network may be provided with a heat-generating clad metal material composed of a conductive material that does not include low-melting point metals and heavy metals.

[0051] According to one aspect of the present invention, a cooking appliance may be provided comprising: a cooking appliance body made of a molded body of a heating type clad metal material, wherein a plurality of layers are laminated and integrated, and the metal layer comprises a metal layer, a graphene heating layer that generates resistive heat by electrical conduction, and an insulating layer interposed between the graphene heating layer and the metal layer to block direct contact between the graphene heating layer and the metal layer.

[0052] For example, a cooking appliance may be provided in which the main body of the cooking appliance is a molded body in the shape of a frying pan, wok, or pot including a curved surface, and the graphene heating layer is continuous without interruption throughout the entire main body of the cooking appliance.

[0053] According to one aspect of the present invention, a cooking appliance may be provided comprising: a molded body of a heating-type clad metal material, wherein a plurality of layers are laminated and integrated, the metal layer, the graphene heating layer which generates resistive heat by electrical conduction, and the insulating layer which is interposed between the graphene heating layer and the metal layer and blocks direct contact between the graphene heating layer and the metal layer; an electrical contact that is electrically connected to the graphene heating layer and drawn out toward the edge of the cooking appliance body; and a detachable handle that is detachably coupled to the electrical contact and conducts electricity to the graphene heating layer.

[0054] For example, a cooking appliance may be provided that further comprises: a power supply electrode (busbar) connected to both ends of the graphene heating layer; and an electrical contact drawn from the power supply electrode (busbar) to a detachable part on the edge side of the cooking appliance body, wherein the electrical contact is disposed on the detachable part and connects to the detachable handle side contact when the detachable handle is coupled to the detachable part.

[0055] For example, a cooking appliance may be provided in which the electrical contact of the detachable part is connected in series with the detachable handle side contact.

[0056] For example, a cooking appliance may be provided in which a switch for opening and closing the current to the graphene heating layer is disposed on the side of the detachable handle, and the cooking appliance body is equipped only with an inactive element electrical structure including the electric contact and the lead wiring connected to the electric contact.

[0057] For example, a cooking appliance may be provided in which the graphene heating layer comprises a plurality of segments divided along the direction of power supply and connected in parallel with each other, and a magnetic control ballast is arranged in series at the power supply connection part of each of the plurality of segments to reduce the current flowing according to the temperature rise of the segment, and a switch is arranged on the side of the detachable handle to open and close the power supply to the graphene heating layer. Effects of the invention

[0058] The disclosed technology may have the following effects. However, this does not mean that a specific embodiment must include all of the following effects or only the following effects; therefore, the scope of the rights of the disclosed technology should not be understood as being limited by this.

[0059] According to the present invention, by interposing an insulating layer between a graphene heating layer and a metal layer, a graphene heating layer that generates resistive heat through electrical conduction is incorporated into a metal material, and the heat generated is efficiently transferred to the cooking surface side without being lost through direct bonding with the metal layer, while simultaneously suppressing excessive temperature rise, thereby providing a heating-type clad metal material.

[0060] In addition, by combining the heat diffusion function of the multilayer metal material with the electric heating of the graphene heating layer, localized overheating and sticking of the cooking surface are suppressed, and cooking performance can be ensured in which the cooking surface is heated evenly throughout.

[0061] In addition, since the graphene heating layer possesses excellent mechanical strength and moldability, the durability of the material is ensured, and the heating layer can be maintained continuously throughout even during the process of forming it into the shape of a cooking utensil.

[0062] In addition, by controlling the electrical connection to the graphene heating layer and the switching of the current through a detachable handle, the electrical structure of the cooking appliance body becomes simpler, making handling and cleaning easier and facilitating product manufacturing.

[0063] In addition, it can be used in various heating environments including gas, induction, and air fryers, and can also be used for cooking by its own electric heating, so it can be widely applied to various heating cookware such as frying pans, woks, and pots.

[0064] The effects of the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description below. Brief explanation of the drawing

[0065] FIG. 1 is a cross-sectional view showing a thickness direction laminated structure of a heating type clad metal material according to one embodiment of the present invention. FIG. 2 is a perspective view showing a cooking appliance equipped with a detachable electrical connection handle according to one embodiment of the present invention. FIG. 3 is a plan view showing a parallel segment matrix of a graphene heating surface according to one embodiment of the present invention. FIG. 4 is a conceptual diagram showing an elongation-responsive compensation challenge network of a curved surface forming part according to one embodiment of the present invention. FIG. 5 is a detailed diagram showing an electrical connection outflow structure from a power supply electrode to a detachable handle according to one embodiment of the present invention. Specific details for implementing the invention

[0066] The description of the present disclosure is merely an example for structural or functional explanation, and therefore the scope of the present disclosure should not be interpreted as being limited by the examples described in the text. That is, since the examples are subject to various modifications and may take various forms, the scope of the present disclosure should be understood to include equivalents capable of realizing the technical concept. Furthermore, the purposes or effects presented in the present disclosure do not imply that a specific example must include all of them or only such effects; therefore, the scope of the present disclosure should not be understood as being limited by them.

[0067] Meanwhile, the meaning of the terms described in this application should be understood as follows. When a component is described as being "connected" to another component, it should be understood that it may be directly connected to the other component, or that there may be other components in between. On the other hand, when a component is described as being "directly connected" to another component, it should be understood that there are no other components in between. Meanwhile, other expressions describing the relationship between components, such as "between" and "exactly between," or "adjacent to" and "directly adjacent to," should be interpreted in the same way.

[0068] A singular expression should be understood to include a plural expression unless the context clearly indicates otherwise, and terms such as "include" or "have" are intended to specify the existence of the implemented features, numbers, steps, actions, components, parts, or combinations thereof, and should be understood not to preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0069] FIG. 1 illustrates a laminated cross-section of a heating-type clad metal material (100) according to one aspect of the present invention, cut in the thickness direction. In FIG. 1, the cooking surface side is the upper side of the drawing, indicating the direction toward the surface where food comes into contact during cooking, and the outer side is the lower side of the drawing, indicating the direction toward the heating source. The heating-type clad metal material (100) is illustrated in a form in which a plurality of layers are stacked sequentially along the thickness direction and integrated into a single plate, and in the following description, the reference numerals indicated in FIG. 1 are used together for each layer and interface structure.

[0070] In one aspect of the present invention, a heating clad metal material (100) may be integrated by stacking a plurality of layers including a metal layer (110), a graphene heating layer (120) that generates resistive heat through electrical conduction, and an insulating layer (130) interposed between the graphene heating layer (120) and the metal layer (110). If the graphene heating layer (120) is directly absorbed and bonded to the metal layer (110), the heat generated at the interface may be absorbed and lost to the metal and not transferred to the cooking surface; therefore, it may be required to interpose an insulating layer (130) between the graphene heating layer (120) and the metal layer (110). By interposing the insulating layer (130) between them to block direct contact between the two, the heat generated from the graphene heating layer (120) can be directed toward the cooking surface without loss due to bonding with the metal.

[0071] In one embodiment, the plurality of layers can be sequentially stacked along the thickness direction and integrated into a single plate, and the integrated heating clad metal material (100) can be used as a material forming the main body of a cooking appliance after subsequent molding. As the plurality of layers are integrated, each layer can move together without being separated from one another, and the electric heating function and the heat diffusion function can be contained together within a single material.

[0072] For example, the heating clad metal material (100) may be composed of 3 to 7 layers based on the metal layers, typically about 5 layers, and the graphene heating layer (120) and the insulating layer (130) may be counted as thin film layers incorporated between the metal layers. As the number of layers increases, different functions can be assigned to each layer.

[0073] In one aspect of the present invention, the metal layer (110) may be understood as a metal of a higher concept as a substrate layer that forms a cooking surface or diffuses heat. The metal layer (110) can spread heat generated from the graphene heating layer (120) and heat transferred from the heating source in a planar direction, thereby mitigating the variation in which heat is locally concentrated, causing the bottom to burn while the sides remain undercooked.

[0074] In one embodiment, the metal layer (110) may be composed of a single layer or a plurality of layers made of different metals. In this case, a metal with relatively fast heat transfer may be placed on the inner side in the thickness direction to widely diffuse heat, and a metal with relatively hardness may be placed on both sides to form the outer and outer surfaces.

[0075] For example, the metal layer (110) may include at least one of stainless steel, aluminum, and iron, and aluminum, which has faster heat transfer than stainless steel, may be used in the portion that rapidly diffuses heat, and stainless steel may be used in the portion that forms the cooking surface and the outer surface. The metal layer (110) is not limited to a specific type of steel and may use any metal commonly used as a kitchen metal material.

[0076] In one aspect of the present invention, the graphene heating layer (120) is a layer that generates resistance heat through electric current, and can function as a planar heating element that generates heat through resistance when a potential difference is applied between the two ends and current flows across the entire surface. The graphene heating layer (120) does not rely solely on an external heating source, but allows the material itself to become a heating source, thereby enabling the cooking surface to be heated in various heating environments, including gas, induction, and air fryers, as well as in environments where a separate heating source is not provided.

[0077] In one embodiment, the graphene heating layer (120) can be formed with a very thin thickness, and the thickness scale may be approximately 0.25 nm. As the thickness becomes thinner, heat transfer in the thickness direction is smoother, but since there is a possibility of local thinning or breakage during the molding process, the graphene heating layer (120) can be integrated and supported together with other layers of the heating type clad metal material (100).

[0078] For example, the graphene used in the graphene heating layer (120) can be understood as a single higher concept and is not limited to its form. Graphene can have a strength approximately 200 times that of iron, which can contribute to the durability of the material and the maintenance of the layer during the molding process.

[0079] In one aspect of the present invention, the insulating layer (130) may be a layer interposed between the graphene heating layer (120) and the metal layer (110) to block direct contact between the two. If the graphene heating layer (120) comes into direct contact with the metal layer (110), current for heating flows to the metal layer (110), making it difficult to establish resistance heating, and heat transfer may also be lost due to interfacial bonding. The insulating layer (130) can serve to cut off electrical contact between them while allowing the heat to pass through to the cooking surface.

[0080] In one embodiment, the insulating layer (130) may partition the space between the graphene heating layer (120) and the metal layer (110) so that they do not combine with each other, thereby ensuring that the graphene heating layer (120) remains separated from the adjacent metal layer (110). In this partitioned state, the heat generated by the graphene heating layer (120) can be transferred to the cooking surface without loss due to combination with the metal.

[0081] For example, the insulating layer (130) may be made of at least one of ceramic, polyimide, or a layer formed by a chemical fixation method and is not limited to a specific material. The thickness and material of the insulating layer (130) may be selected to allow for smooth heat transfer in the thickness direction while maintaining electrical insulation.

[0082] In one aspect of the present invention, as a metal layer (110), an insulating layer (130), and a graphene heating layer (120) are stacked in multiple layers and integrated, the heating clad metal material (100) can provide both electric heating and heat diffusion as a single material. In this integrated state, heat can spread throughout the entire material without being concentrated in a specific area, so that the cooking surface can be heated without localized burning or undercooking.

[0083] In one embodiment, the heating clad metal material (100) is configured such that a plurality of layers behave as a single unit without being separated from each other, so that the stacking relationship of each layer can be maintained even if the plate is subsequently bent or pressed to form it. As a result, the heating clad metal material (100) can be processed not only into a flat shape but also into a shape including a curved surface.

[0084] For example, the heating clad metal material (100) can be molded into a material that forms the body of a cooking utensil such as a frying pan, wok, or pot, and in this case, electric heating by the graphene heating layer (120) and heat diffusion by the metal layer (110) can be provided together.

[0085] In one aspect of the present invention, referring to FIG. 1, the heating clad metal material (100) may further include an additional metal layer (114) laminated on one side in the direction in which a plurality of layers are laminated. The additional metal layer (114) is a layer in which one additional metal layer is placed on top of an already laminated multilayer, and may serve to extend the heat transfer path of the material or complement the surface characteristics of that side.

[0086] In one embodiment, the additional metal layer (114) may be disposed on either the outermost surface of the cooking surface or the outermost surface of the outermost surface among the plurality of layers, and FIG. 1 illustrates a form in which the additional metal layer (114) is disposed on the outermost surface of the cooking surface. The additional metal layer (114) can be added on top of the layer already formed by the stacking relationship of the layers below it without disrupting it, and together they can be integrated into a single plate.

[0087] For example, the additional metal layer (114) may be made of a metal selected to suit the characteristics required on the surface on which it is placed, and its thickness may also be determined according to the required characteristics and is not limited to a specific metal or thickness.

[0088] In one aspect of the present invention, referring to FIG. 1, the heating clad metal material (100) may further include a heat transfer accelerating metal layer (114) that is laminated on a plurality of layers of cooking surfaces to accelerate heat transfer to the cooking surfaces. The heat transfer accelerating metal layer (114) is placed on the outermost side of the cooking surfaces and can serve to rapidly transfer heat rising from the layers below to the cooking surfaces.

[0089] In one embodiment, the heat transfer accelerating metal layer (114) may be made of a metal that transfers heat faster than the metal layer (111) on the cooking surface side, and accordingly, heat generated from the graphene heating layer (120) and directed toward the cooking surface side can be evenly spread across the entire cooking surface. By adding the heat transfer accelerating metal layer (114), the thermal response on the cooking surface side can be accelerated.

[0090] For example, copper may be used as a metal with fast heat transfer in the heat transfer acceleration metal layer (114), and any metal with a higher concept that has faster heat transfer than the metal layer (111) on the cooking surface side is sufficient and is not limited to a specific metal.

[0091] In one aspect of the present invention, referring to FIG. 1, the metal layer (110) may include a plurality of metal layers, and the plurality of metal layers may include a heat-diffusing metal layer (112) which has faster heat transfer than the remaining metal layers and is disposed inside the thickness direction of the plurality of layers to diffuse heat. The heat-diffusing metal layer (112) may serve as a diffusion core that widely spreads heat generated in the graphene heating layer (120) and heat transferred from the heat source in the plane direction.

[0092] In one embodiment, the heat diffusion metal layer (112) is positioned inward in the thickness direction so that heat can be divided and transferred to the metal layers on both sides thereof, thereby mitigating the variation where heat is concentrated in a specific area, causing the bottom to burn while the sides remain undercooked. The heat diffusion metal layer (112) can be made thicker than other metal layers to increase the capacity to hold and spread heat.

[0093] For example, aluminum, which has faster heat transfer than the metal forming the metal layer (111) on the cooking surface side, may be used for the heat diffusion metal layer (112), and aluminum can transfer heat about three times faster than stainless steel. The heat diffusion metal layer (112) is sufficient if it is a metal of a higher concept that has faster heat transfer than the remaining metal layer, and is not limited to a specific metal.

[0094] In one aspect of the present invention, referring to FIG. 1, a heat-diffusing metal layer (112) may be interposed between a cooking surface-side metal layer (111) and an insulating layer (130) that are positioned on the cooking surface side. By placing the heat-diffusing metal layer (112) in this position, heat directed from the graphene heating layer (120) through the insulating layer (130) toward the cooking surface side may spread first in the plane direction before reaching the cooking surface-side metal layer (111).

[0095] In one embodiment, the heat-diffusing metal layer (112) is in contact with the cooking surface side of the insulation layer (130) and receives heat from it, and can evenly transfer it to the cooking surface side metal layer (111) above it. At such an interposed position, the heat-diffusing metal layer (112) can receive heat from the heating layer and heat from an external heat source together and transfer it uniformly to the cooking surface side.

[0096] For example, the layers may be arranged in the order of a cooking surface side metal layer (111), a heat diffusion metal layer (112), and an insulation layer (130) from the cooking surface side, so that the diffusion core is located directly below the cooking surface side metal layer (111), and this arrangement can be used to evenly distribute the temperature of the cooking surface.

[0097] In one aspect of the present invention, referring to FIG. 1, the metal layer (110) may include an outer metal layer (113) disposed on the side opposite to the cooking surface with respect to the graphene heating layer (120) among a plurality of layers, and the outer metal layer (113) may be a magnetic metal layer. The outer metal layer (113) may be a layer that forms the outer side opposite to the cooking surface, that is, the side facing the heating source.

[0098] In one embodiment, as the outer metal layer (113) has magnetism, the outer metal layer (113) can react to the magnetic field in a heating environment that generates heat using a magnetic field to raise the temperature of the material. Thus, the heating type clad metal material (100) can respond to magnetic induction heating through the outer metal layer (113) along with electric heating by the graphene heating layer (120).

[0099] For example, the outer metal layer (113) may be made of magnetic stainless steel, and any magnetic metal of a higher concept that responds to a magnetic field is sufficient and is not limited to a specific type of steel.

[0100] In one aspect of the present invention, referring to FIG. 1, the heating clad metal material (100) may further include an insulating protective layer (140) disposed on the opposite side of the two sides of the graphene heating layer (120) where the insulating layer (130) is interposed, thereby electrically insulating the graphene heating layer (120) from an adjacent metal layer. The insulating protective layer (140) may be a layer that performs the same electrical insulation as that performed by the insulating layer (130) on the opposite side of the graphene heating layer (120).

[0101] In one embodiment, the graphene heating layer (120) may be kept in a state where both sides are separated from adjacent metal layers, with one side in contact with the insulating layer (130) and the other side in contact with the insulating protective layer (140). As both sides are insulated in this way, the current flowing through the graphene heating layer (120) does not leak out to either metal layer and can lead to resistive heating within the graphene heating layer (120).

[0102] For example, the insulating protective layer (140) may be made of a layer that does not excessively hinder heat transfer in the thickness direction while maintaining electrical insulation, and the material and thickness may be selected within the range where insulation is maintained and are not limited to a specific material.

[0103] In one aspect of the present invention, referring to FIG. 1, a plurality of layers may be stacked in the order of a cooking surface side metal layer (111), a heat-diffusing metal layer (112), an insulating layer (130), a graphene heating layer (120), an insulating protective layer (140), and an outer metal layer (113) from the cooking surface side. According to this order, the metal forming the cooking surface and the heat-spreading core may be positioned on the cooking surface side, the graphene heating layer (120) responsible for electric heating and the insulating layers on both sides thereof may be positioned on the inside in the thickness direction, and the metal facing the heat source may be positioned on the outside.

[0104] In one embodiment, the graphene heating layer (120) has a cooking surface side in contact with an insulating layer (130) and an opposite side in contact with an insulating protective layer (140), so that both sides can be electrically insulated from adjacent metal layers. Accordingly, the graphene heating layer (120) can be placed between two insulating layers without directly contacting either the cooking surface side metal layer (111) and the heat diffusion metal layer (112) on the cooking surface side or the outer metal layer (113) on the outer side.

[0105] For example, in such a stacking order, the heat of the graphene heating layer (120) can pass through the insulating layer (130) on the cooking surface side, through the heat diffusion metal layer (112) and the metal layer (111) on the cooking surface side, and the outer metal layer (113) can form a surface facing the heat source, so that the external heat source and the heat of the graphene heating layer (120) can be received together.

[0106] In one aspect of the present invention, referring to FIG. 1, the insulating layer (130) may be a dielectric interlayer (130) having both electrical insulation and thermal conductivity, which electrically insulates the graphene heating layer (120) and the metal layer (110) while transferring the heat from the graphene heating layer (120) to the cooking surface. The dielectric interlayer (130) may be a layer having both properties of electrically separating the graphene heating layer (120) and the metal layer (110) while allowing heat to pass through them in the thickness direction.

[0107] In one embodiment, in order to generate resistive heating by flowing current through the graphene heating layer (120), the graphene heating layer (120) must not come into direct contact with the adjacent metal layer (110). This is because if there is direct contact, current flows into the metal layer (110), making it difficult to generate resistive heating, and heat transfer may also be lost due to interfacial bonding. The dielectric interlayer (130) can cut off electrical contact between them to prevent current from leaking into the metal layer (110), while allowing the heat generated from the graphene heating layer (120) to pass through in the thickness direction and be sent to the cooking surface. Here, the role of the dielectric interlayer (130) may be to electrically insulate while allowing heat to pass through, rather than to block heat.

[0108] For example, the dielectric interlayer (130) may be made of a material that facilitates heat transfer in the thickness direction while maintaining electrical insulation, and the material and thickness may be selected to facilitate heat transfer in the thickness direction within a range where electrical insulation is secured, and are not limited to a specific material.

[0109] In one aspect of the present invention, referring to FIG. 1, a dielectric interlayer (130) is interposed on the cooking surface side of the graphene heating layer (120) so as to electrically insulate the graphene heating layer (120) from the cooking surface side metal layer (111) while thermally bonding the graphene heating layer (120) and the cooking surface side metal layer (111). As the dielectric interlayer (130) is placed on the cooking surface side, insulation and heat transfer can be achieved together in the direction in which the heating of the graphene heating layer (120) is directed.

[0110] In one embodiment, the dielectric interlayer (130) electrically disconnects the graphene heating layer (120) and the metal layer (111) on the cooking surface side, while connecting the two layers so that heat can pass between them in the thickness direction. As a result, heat generated in the graphene heating layer (120) passes through the dielectric interlayer (130) to the metal layer (111) on the cooking surface side and can then be directed toward the cooking surface.

[0111] For example, in a configuration where the dielectric interlayer (130) is interposed on the cooking surface side, the opposite side of the graphene heating layer (120) is insulated by an insulating protective layer (140), so that both sides of the graphene heating layer (120) can be kept separated from the adjacent metal layer.

[0112] In one aspect of the present invention, the thickness of the dielectric interlayer (130) can be determined to a range that simultaneously satisfies the property of allowing heat from the graphene heating layer (120) to pass to the cooking surface and the property of electrically insulating from an adjacent metal layer. Since the thinner the dielectric interlayer (130), the lower the thermal resistance in the thickness direction, which is advantageous for heat transfer, while electrical insulation can be stably secured only when it is of a certain thickness or greater, the range can be determined to a thickness that simultaneously satisfies both properties.

[0113] In one embodiment, the thickness of the dielectric interlayer (130) may be 10 to 200 micrometers, which is a wide range of windows where heat transfer and insulation reliability are both ensured. Within this range, the dielectric interlayer (130) can maintain electrical insulation between the graphene heating layer (120) and the metal layer (110) while allowing heat to pass through in the thickness direction.

[0114] For example, as the thickness of the dielectric interlayer (130) is closer to the lower end of the range, heat transfer in the thickness direction becomes more favorable, and as it is closer to the upper end, insulation reliability can be sufficient, and the thickness can be selected within the range according to the balance of required heat transfer and insulation reliability.

[0115] In one aspect of the present invention, the thickness of the dielectric interlayer (130) can be narrowly set to 25 to 100 micrometers within a window where heat transfer and insulation reliability are both satisfied. This narrow range can be understood as a section where the degree of smooth heat transfer in the thickness direction and the degree of stable electrical insulation are both secured.

[0116] In one embodiment, when the thickness of the dielectric interlayer (130) is 25 to 100 micrometers, the balance between the two properties can be managed more narrowly than widely between the thin side, which is advantageous for heat transfer, and the thick side, which has margin for insulation reliability.

[0117] For example, if the thickness of the dielectric interlayer (130) is set to the narrow range, the thickness can be selected in a direction that reduces the variation in properties according to thickness under cooking conditions where heat transfer and insulation reliability are required together.

[0118] In one aspect of the present invention, the thickness of the dielectric interlayer (130) can be most preferably set to 40 to 60 micrometers within a window where heat transfer and insulation reliability are both satisfied. This range can be understood as a thickness where the degree of heat transfer in the thickness direction and electrical insulation are typically balanced.

[0119] In one embodiment, when the thickness of the dielectric interlayer (130) is 40 to 60 micrometers, the heat from the graphene heating layer (120) passes smoothly in the thickness direction, while the electrical insulation between the graphene heating layer (120) and the metal layer (110) can be stably maintained.

[0120] For example, setting the thickness of the dielectric interlayer (130) to the above range may be adopted as a representative thickness under usage conditions where heat transfer and insulation reliability are required together, and this range may be a value included in the broad range and narrow range presented above.

[0121] In one aspect of the present invention, the dielectric interlayer (130) may be made of a material that maintains electrical insulation and ensures a degree of heat passing in the thickness direction, and the thermal conductivity may be 5 to 15 W / m·K. The thermal conductivity of the dielectric interlayer (130) may be a physical property that determines how smoothly the heat from the graphene heating layer (120) passes in the thickness direction.

[0122] In one embodiment, if the thermal conductivity of the dielectric interlayer (130) is within the above range, the dielectric interlayer (130) can function as a thermal path that passes heat to the cooking surface while maintaining electrical insulation between the graphene heating layer (120) and the metal layer (110). If the thermal conductivity is lower than the above range, the thermal resistance in the thickness direction increases, which may slow down heat transfer, and if an excessively high value is pursued, it may become difficult to satisfy electrical insulation at the same time; therefore, the above range may be selected to ensure heat transfer while maintaining insulation.

[0123] For example, the thermal conductivity of the dielectric interlayer (130) can be determined by a commonly used thermal conductivity measurement procedure, and the specific value can be determined within the above range depending on the material and thickness used for the dielectric interlayer (130).

[0124] In one aspect of the present invention, the dielectric interlayer (130) may have a thickness greater than or equal to a lower thickness limit having an dielectric breakdown voltage greater than or equal to the feed voltage applied to the graphene heating layer (120). Since the dielectric interlayer (130) is a layer placed between the graphene heating layer (120) and an adjacent metal layer (110) and withstands the feed voltage, it may have a thickness greater than that which prevents the insulation from collapsing at the feed voltage.

[0125] In one embodiment, the lower thickness limit of the dielectric interlayer (130) can be set to be greater than the value obtained by dividing the power supply voltage by the dielectric breakdown electric field of the dielectric interlayer (130) material. That is, the power supply voltage is V o p, dielectric breakdown electric field of the dielectric interlayer (130) material E B When denoted as D, the thickness t of the dielectric interlayer (130) i ns is V o p / E B It can be D or higher, and above this lower thickness limit, the dielectric interlayer (130) can secure an insulating withstand voltage corresponding to the power supply voltage.

[0126] For example, the dielectric interlayer (130) maintains a thickness greater than the lower limit for insulation, but since it is advantageous for heat transfer in the thickness direction to be thinner, a thin thickness that is possible within the range satisfying the lower limit for insulation thickness can be selected under a relationship where the thermal resistance in the thickness direction is proportional to the thickness of the dielectric interlayer (130). Accordingly, the thickness of the dielectric interlayer (130) can be determined between the lower limit for securing insulation withstand voltage and thinness for heat transfer.

[0127] FIG. 5 illustrates an electrical connection outflow structure from a power supply electrode to a detachable handle, shown as an enlarged cross-section of a portion cut in the thickness direction near the edge (213) of the cooking appliance body. FIG. 5 illustrates, in order along the current path from the embedded heating layer to the detachable part, an exposed end (520) in which the opposite end of the embedded graphene heating layer (120) is exposed and extended to the edge of the clad, a first power supply electrode (busbar) (510) and a second power supply electrode (busbar) (511) as a power supply electrode (busbar) (500) formed on the exposed end (520), an insulating sleeve (530) covering the exposed end (520) and the power supply electrode, an outflow wiring (550) connected from the power supply electrode, and an electrical contact (540) of the detachable part (560) on the edge (213) side. In FIG. 5, a detachable handle (400) that is detachably coupled to the detachable part (560), a handle-side contact (410), and a switch (420) positioned on the handle side are shown together in the form of separate circuit symbols, indicating that power switching is performed on the handle side. In the following description, the reference numerals indicated in FIG. 5 are used for each component of the power supply withdrawal structure.

[0128] In one aspect of the present invention, referring to FIG. 5, the graphene heating layer (120) may have an exposed end (520) in which opposing ends are exposed and extended to the edges of a plurality of layers, and the heating type clad metal material (100) may further include a power supply electrode (busbar) (500) formed at the exposed end (520) and electrically connected to the graphene heating layer (120), and an insulating sleeve (530) that wraps the exposed end (520) and insulates the power supply electrode (500) from an adjacent metal layer. The exposed end (520) may be a portion in which the ends of the graphene heating layer (120) are pulled out to the edges of the material so that electricity can be connected from the outside to the graphene heating layer (120) embedded inside the clad.

[0129] In one embodiment, the power supply electrode (500) is formed on the exposed end (520) and electrically connected to the graphene heating layer (120), and may be an electrode that divides and supplies current so that current can flow over the entire surface of the graphene heating layer (120). The insulating sleeve (530) wraps the exposed end (520) and the power supply electrode (500), so that the power supply electrode (500) can be diverted and pulled out to the edge of the material while being insulated so that it does not come into contact with an adjacent metal layer, such as the metal layer (111) on the cooking surface side or the metal layer (113).

[0130] For example, the exposed ends (520) are provided at opposite ends of the graphene heating layer (120), and a power supply electrode (500) is formed at each of them, so that current can flow across the surface of the graphene heating layer (120) between the two power supply electrodes. At this time, as the power supply electrode (500) is insulated from the adjacent metal layer by the insulating sleeve (530), the current for power supply can flow to the graphene heating layer (120) without leaking into the metal layer.

[0131] In one aspect of the present invention, an exposed end (520) that is exposed and extended to the edge of the plurality of layers may be formed at each of the opposing ends of the graphene heating layer (120), and a first power supply electrode (busbar) (510) and a second power supply electrode (busbar) (511) may be disposed at each of the exposed end (520) of the opposing ends and may be electrically connected to the graphene heating layer (120) at a position facing each other. If the power supply electrode (busbar) is disposed only at one end, the current may be concentrated in that vicinity and may be difficult to flow evenly across the entire surface of the graphene heating layer (120), but if the first power supply electrode (busbar) (510) and the second power supply electrode (busbar) (511) are disposed at each of the opposing ends, the current may flow across the surface between the two electrodes.

[0132] In one embodiment, the first power supply electrode (busbar) (510) and the second power supply electrode (busbar) (511) are each extended along two opposing sides of the graphene heating layer (120), so that a power supply direction connecting the two sides is formed across the entire surface of the graphene heating layer (120). As the two electrodes are connected across the entire opposing sides, the inflow and outflow of current can occur across the entire side without being limited to a specific point.

[0133] For example, by arranging the first power supply electrode (busbar) (510) and the second power supply electrode (busbar) (511) in opposite positions, current can be passed across the entire surface of the graphene heating layer (120), and the entire surface can generate resistive heat while mitigating the problem of the current being concentrated on one side and only a specific area being excessively heated.

[0134] In one aspect of the present invention, the power supply electrode (busbar) (500) may be electrically connected only to the graphene heating layer (120) and not connected to the adjacent metal layer (110). If the power supply electrode (busbar) (500) is connected to both the graphene heating layer (120) and the adjacent metal layer (110), the current for power supply may be short-circuited to the metal layer (110), making it difficult to establish resistance heating of the graphene heating layer (120). Therefore, it may be required that the power supply electrode (busbar) (500) be connected only to the graphene heating layer (120) and insulated from the adjacent metal layer (110).

[0135] In one embodiment, the exposed end (520) of the graphene heating layer (120) and the power supply electrode (busbar) (500) formed thereon are wrapped by an insulating sleeve (530) so that they can be drawn toward the edge of the plurality of layers without contacting the adjacent metal layer (110). The insulating sleeve (530) blocks the metal layer (110) and the power supply electrode (busbar) (500) in the path where the exposed end (520) extends toward the edge, thereby preventing the two from coming into electrical contact during the drawing process.

[0136] For example, the power supply electrode (busbar) (500) can be drawn out along the insulating sleeve (530) bypassing the adjacent metal layer (110) to the edge side of the plurality of layers, thereby allowing the power supply path to the graphene heating layer (120) to be connected to the outside without being short-circuited with the metal layer (110).

[0137] In one aspect of the present invention, an anchoring protrusion (150) is formed at the interface between the insulating layer (130) and the graphene heating layer (120) as shown in FIG. 1, so that the graphene heating layer (120) can be mechanically engaged with the insulating layer (130). The graphene heating layer (120) is a very thin layer and may slide or peel off along the interface if it only comes into flat contact with the insulating layer (130). However, when the anchoring protrusion (150) is formed at the interface, the graphene heating layer (120) can be restrained in the direction of the interface by being caught in the curvature of the protrusion.

[0138] In one embodiment, the anchoring irregularities (150) form a curvature in which the surface of the insulating layer (130) and the graphene heating layer (120) interlock with each other, thereby restraining relative movement in the shear direction acting along the interface. In this interlocked state, the graphene heating layer (120) may be prevented from locally detaching from the insulating layer (130) during the process of bending or pressing the plate material to form it.

[0139] For example, the anchoring irregularities (150) may be formed as fine sawtooth shapes or irregular textures, and may be formed to a extent that does not impair the function of the insulating layer (130) in blocking direct contact between the graphene heating layer (120) and the adjacent metal layer (110). Even if irregularities are formed at the interface, the state in which the insulating layer (130) partitions the two can be maintained.

[0140] In one aspect of the present invention, an adhesive primer layer (155) is interposed at the interface between the insulating layer (130) and the graphene heating layer (120) as shown in FIG. 1, thereby mediating adhesion between the graphene heating layer (120) and the insulating layer (130). In addition to the anchoring protrusions (150) mechanically interlocking the graphene heating layer (120) with the insulating layer (130), the adhesive primer layer (155) can chemically bond the interface between the two so that interlocking and adhesion work together.

[0141] In one embodiment, the adhesive primer layer (155) is interposed along the curvature of the interface where the anchoring irregularities (150) are formed, so that the mechanical restraint by the irregularities and the adhesion by the primer overlap at the same interface. As a result, the graphene heating layer (120) can be more firmly fixed to the insulating layer (130) against the stress of the molding process.

[0142] For example, the adhesive primer layer (155) may be interposed as a thin layer within a range that does not impair the function of insulating the insulating layer (130) between the graphene heating layer (120) and the adjacent metal layer (110), and is not limited to a specific material.

[0143] FIG. 4 illustrates an enlarged cross-section of a local portion including a curved portion (212) of a cooking utensil cut in the thickness direction, and a concept of a compensation conductive network (610) composited in the graphene heating layer (120) of the curved portion (212). In FIG. 4, the direction references for the cooking surface side and the outer side are as defined in FIG. 1, and the cross-section shows an insulating layer (130), a graphene heating layer (120), and an insulating protective layer (140) in sequence, indicating that the graphene heating layer (120) is supported on both sides by a continuous support surface formed by the insulating layer (130) and the insulating protective layer (140). At a point where the curved portion (212) is greatly bent and extended, a strain-relief shape (160) formed in the graphene heating layer (120) is also shown, and inside the graphene heating layer (120), a compensation conductive network (610) consisting of conductive fibers (611) and contact points (612) between the fibers is superimposed and shown. In a separate inset of FIG. 4, a relationship is shown in which a complete insulation gap (320) between the heating section segments (311) penetrates the graphene heating layer (120) and the compensation conductive network (610). In the following description, the reference numerals indicated in FIG. 4 are used for each component.

[0144] In one aspect of the present invention, the heating clad metal material (100) may be a molded body including a curved portion (212), and the graphene heating layer (120) may be continuously connected without interruption by engaging with the anchoring irregularities (150) throughout the molded body including the curved portion (212). A thin graphene heating layer (120) may be stretched and locally broken during the process of forming a plate material to have a curved portion (212), but if the graphene heating layer (120) is fixed by engaging with the anchoring irregularities (150) even at the curved portion (212), the detachment or breakage at a specific point during the stretching process is suppressed, so that the heating layer can be continuous.

[0145] In one embodiment, since the graphene heating layer (120) is a resistive heating element through which current flows, the path through which current flows can also be continuous across the curved portion (212) without interruption. If the graphene heating layer (120) is locally interrupted, the current path is severed at that point, and a region where heating does not occur may be created; however, if the heating layer is continuous across the entire curved portion (212), the current path is maintained, and heating can occur even in the curved portion (212).

[0146] For example, the heating clad metal material (100) can be formed into a molded body having a curved portion (212) with a deep side wall, such as a wok or a pot, and even in such a deep molded body, the graphene heating layer (120) can be extended across the entire area including the curved portion (212) so that the entire cooking surface can be heated.

[0147] In one aspect of the present invention, the thickness of the graphene heating layer (120) in the curved portion (212) can be maintained at 50% or more of the thickness of the graphene heating layer (120) in the flat portion. If the graphene heating layer (120) is greatly extended in the curved portion (212) and becomes excessively thin, the sheet resistance at that point may increase locally, causing the current density to become uneven. However, if the thickness in the curved portion (212) is maintained at a certain ratio or more of the thickness in the flat portion, the increase in sheet resistance in the curved portion (212) is limited, and the current density can be maintained evenly.

[0148] In one embodiment, the ratio of the thickness of the graphene heating layer (120) in the curved portion (212) to the thickness in the flat portion can be confirmed by observing the cross-section of the molded heating clad metal material (100), and the larger this ratio, the smaller the thickness variation between the curved portion (212) and the flat portion, so that the heating distribution can be formed evenly.

[0149] For example, if the thickness of the curved portion (212) is 50% or more of the thickness of the flat portion, the heat disparity caused by the increase in local resistance of the curved portion (212) is mitigated, so that heat can be generated relatively evenly throughout the molded body including the curved portion (212).

[0150] In one aspect of the present invention, the thickness of the graphene heating layer (120) in the curved portion (212) may be maintained at a ratio greater than the aforementioned ratio with respect to the thickness of the graphene heating layer (120) in the flat portion. The greater the thickness ratio in the curved portion (212), the greater the increase in surface resistance of the curved portion (212) can be reduced, and the current density difference between the curved portion (212) and the flat portion can be further mitigated.

[0151] In one embodiment, if the thickness ratio in the curved portion (212) is maintained at a larger value, the thinning caused by elongation in the curved portion (212) is limited to a narrow width, so that the heat distribution can be formed more evenly across the entire molded body including the curved portion (212).

[0152] For example, the thickness of the graphene heating layer (120) in the curved portion (212) may be 70% or more of the thickness of the graphene heating layer (120) in the flat portion, and in this case, thinning in the curved portion (212) is further restricted so that the heat distribution can be formed more evenly across the entire molded body including the curved portion (212).

[0153] In one aspect of the present invention, the thickness of the graphene heating layer (120) in the curved portion (212) is maintained at a ratio greater than the aforementioned ratio to the thickness of the graphene heating layer (120) in the flat portion, so that it can reach a level nearly equivalent to the thickness in the flat portion. When the thickness of the curved portion (212) and the flat portion reach a level nearly equivalent, the increase in local resistance in the curved portion (212) is minimized, and the current density can be maintained nearly uniformly across the entire area including the curved portion (212).

[0154] In one embodiment, the molded body in which the thickness ratio in the curved portion (212) is maintained in this way can be formed with the smallest heat generation difference between the curved portion (212) and the flat portion, so that the entire cooking surface can be heated evenly even in a molded body with a deep curved portion (212), such as a wok or a pot.

[0155] For example, the thickness of the graphene heating layer (120) in the curved portion (212) may be 85% or more of the thickness of the graphene heating layer (120) in the flat portion, and in this case, the thickness of the curved portion (212) and the flat portion are nearly equal, so that the increase in local resistance in the curved portion (212) is minimized and the current density can be maintained nearly uniformly across the entire area including the curved portion (212).

[0156] In one aspect of the present invention, the graphene heating layer (120) may be formed on a curved portion (212) and may have a strain-relief shape (160) that disperses forming stress and thermal expansion stress. On the curved portion (212), forming stress when forming a plate material and thermal expansion stress when repeated heating and cooling may be concentrated on the graphene heating layer (120). When a strain-relief shape (160) is formed on the graphene heating layer (120), this stress is dispersed along the shape, thereby mitigating concentration at a specific point.

[0157] In one embodiment, the strain-relief shape (160) may include at least one of a dividing portion, a wrinkle portion, and a recess portion formed in the graphene heating layer (120). The dividing portion may relieve stress by dividing a portion of the heating layer along the direction in which stress is concentrated, the wrinkle portion may absorb elongation by forming a bend along the curved surface, and the recess portion may disperse the point where stress accumulates by being formed locally concave.

[0158] For example, the strain-relief shape (160) can suppress the graphene heating layer (120) from breaking due to stress at the curved portion (212), thereby contributing to the graphene heating layer (120) remaining continuous throughout the molded body including the curved portion (212).

[0159] FIG. 3 illustrates a graphene heating layer (120) as a plan view from the side of the heating surface, showing a segment matrix (310) divided into multiple segments along the power supply direction. In FIG. 3, a first power supply electrode (busbar) (510) and a second power supply electrode (busbar) (511) are respectively arranged along the left and right sides, and the direction in which current flows between the two electrodes is defined as the power supply direction. The heating surface between the two electrodes is shown as a plurality of segments (311) divided parallel to each other along the power supply direction, and a fully insulating gap (320) with an interlocking shape is shown at the boundary between adjacent segments (311), and a self-regulating ballast (330) consisting of long, narrow ballast stripes (331) is shown at the power supply connection portion of each segment (311). In the following description, the reference numerals indicated in FIG. 3 are used for each component.

[0160] In one aspect of the present invention, a graphene heating layer (120) is provided with a first power supply electrode (busbar) (510) and a second power supply electrode (busbar) (511) spaced apart from each other, and the graphene heating layer (120) may form a segment matrix (310) comprising a plurality of segments (311) divided along the power supply direction through which current flows between the first power supply electrode (busbar) (510) and the second power supply electrode (busbar) (511). If the graphene heating layer (120) is made up of only one continuous surface, the entire heating surface is bound into a single current path, but if it is divided into a plurality of segments (311) along the power supply direction, the heating surface can be divided into individual heating sections in the form of segments (311).

[0161] In one embodiment, a plurality of segments (311) may each be connected in parallel to a first feed electrode (busbar) (510) and a second feed electrode (busbar) (511). Each segment (311) forms an individual current path that is fed from the first feed electrode (busbar) (510) and leads to the second feed electrode (busbar) (511), and these paths may be placed side by side between the two electrodes to form a parallel connection.

[0162] For example, when multiple segments (311) are connected in parallel between two electrodes, the current flowing through each segment (311) can be individually determined by the path resistance of the segment (311), and even if the current of one segment (311) changes, the current path of another segment (311) can be maintained separately from it. Thus, the segment matrix (310) can form a structure that divides the heating surface into segment (311) units.

[0163] In one aspect of the present invention, each of the plurality of segments (311) may have a stripe shape extending along the power supply direction. If the segments (311) are formed in a stripe shape extending along the power supply direction, the current path between the first power supply electrode (busbar) (510) and the second power supply electrode (busbar) (511) may be formed straight along each stripe.

[0164] In one embodiment, a plurality of segments (311) may form a plurality of stripes arranged side by side in a direction intersecting the power supply direction, and each end of each stripe may be connected to a first power supply electrode (busbar) (510) and a second power supply electrode (busbar) (511), respectively, to form parallel with each other.

[0165] For example, by making the segment (311) into a stripe shape, the heating surface is divided into parallel bands along the power supply direction, and each band can be treated as an individual heating section.

[0166] In one aspect of the present invention, a plurality of segments (311) may be a plurality of tile shapes arranged two-dimensionally along the surface of the graphene heating layer (120). If the segments (311) are formed as tile shapes divided horizontally and vertically along the surface rather than as stripes that extend along the power supply direction, the heating surface may be divided into segments (311) in both the power supply direction and the direction intersecting therewith.

[0167] In one embodiment, a plurality of tile-shaped segments (311) arranged in two dimensions are each connected in parallel to a first power supply electrode (busbar) (510) and a second power supply electrode (busbar) (511), so that a local area of ​​the heating surface can be treated as an individual heating section in tile units.

[0168] For example, if the segments (311) are arranged in a two-dimensional shape in a tile shape, the heating surface is subdivided into smaller local sections, so that the condition of a specific area can be managed on a tile-by-tile basis.

[0169] In one aspect of the present invention, a complete insulation gap (320) is formed at the boundary between a plurality of segments (311) to block in-plane current flow between adjacent segments (311). If the segments (311) are connected by a conductive path, current from one segment (311) can bypass along the plane to a neighboring segment (311). However, if the boundary between the segments (311) is partitioned by a complete insulation gap (320), this in-plane bypass path is cut off, and each segment (311) can be electrically separated from one another.

[0170] In one embodiment, the complete insulation gap (320) may be arranged in an interdigital shape or a zigzag shape so that the heat generation areas of adjacent segments (311) interlock with each other in the projection onto the cooking surface. If the complete insulation gap (320) is formed as a simple straight line boundary, a line where no heat is generated along the boundary line may be projected directly onto the cooking surface, but if arranged in an interdigital shape or a zigzag shape, the insulation gap of one segment (311) may interlock with and cancel out the heat generation areas of neighboring segments (311) in the projection onto the cooking surface.

[0171] For example, if the complete insulation gap (320) is arranged in an interdigital shape or a zigzag shape, the in-plane current between the segments (311) is blocked, and a continuous line is not left where heat is not applied to the cooking surface.

[0172] In one aspect of the present invention, a plurality of segments (311) each have a graphene heating layer (120) that is continuous without interruption within each segment and can be electrically separated only from one another by a complete insulation gap (320). The division into segments (311) does not involve slicing the entire heating surface and breaking it into the interior of each segment (311), but rather the interior of the segment (311) is maintained as a single continuous heating surface and electrical separation can be achieved only at the boundary between the segments (311) by a complete insulation gap (320).

[0173] In one embodiment, a graphene heating layer (120) is connected within each segment (311) so that the current path and heating within the segment (311) are continuous, and between the segments (311) a complete insulation gap (320) can block in-plane current flow. Thus, the continuity of the heating surface is maintained within each segment (311), and electrical isolation can be established only between the segments (311).

[0174] For example, if the continuity within the segment (311) and the separation between the segments (311) are established together in this way, the heat continuity across the entire heat surface and the electrical independence of the segment (311) unit can coexist at different levels.

[0175] In one aspect of the present invention, a self-regulating ballast (330) may be arranged in series at the power supply connection portion for each of the first power supply electrode (busbar) (510) or the second power supply electrode (busbar) (511) of each of the plurality of segments (311), and the self-regulating ballast (330) may be a resistance element that reduces the current flowing through the segment (311) by increasing its resistance as the temperature of the segment (311) rises. When the self-regulating ballast (330) is placed in series at the power supply connection portion of each segment (311), the resistance of the ballast (330) is added to the current path resistance of the segment (311), so that the temperature of the segment (311) can be converted into the resistance of the ballast (330) and reflected in the current.

[0176] In one embodiment, the self-regulating ballast (330) may be a ballast stripe (331) in which the metal layer (110) among the plurality of layers is patterned into a long and narrow fine parallel stripe. Instead of adding a separate element, the metal layer (110) itself forming the heating clad metal material (100) can be patterned into a long and narrow stripe shape to form a resistance element, and as the stripe is made longer and narrower, the reference resistance increases, so the amount of resistance change for the same temperature change can increase.

[0177] For example, the ballast stripe (331) may have a constant resistance temperature coefficient behavior in which resistance increases continuously without abrupt changes such as Curie transitions when the temperature rises, and may not significantly hinder power supply when the temperature of the segment (311) is low, but may act to gradually reduce the current of the segment (311) when the temperature rises. As the self-regulating ballast (330) is arranged in series with the power supply connection of each segment (311), each segment (311) may form a heating section in which the current is individually regulated according to its own temperature.

[0178] In one aspect of the present invention, the ballast stripe (331) may be formed in a long, narrow shape such that the ratio of length to width falls within a certain range. As the ballast stripe (331) is formed longer relative to its width, the reference resistance of the current path increases, and the amount of resistance change for the same temperature change also increases. This change in resistance of the ballast stripe (331) placed in series with the power supply connection may determine the extent to which the current flowing through the segment (311) is controlled.

[0179] In one embodiment, as the ratio of length to width increases, the current suppression sensitivity corresponding to the temperature rise of the segment (311) may increase; however, if the reference resistance becomes excessively large, the normal resistance loss during normal cooking may also increase, so the ratio of length to width may be selected within a range where both the control sensitivity and the normal loss are considered. The ballast stripe (331) shown in FIG. 3 can implement this shape ratio in a form where multiple strands extend side by side along the direction of power supply.

[0180] For example, the ratio of length to width of the ballast stripe (331) may be 5 to 100. If the ratio of length to width is 5 or more, the reference resistance and resistance change amount required for self-regulation can be secured, and if it is 100 or less, the constant resistance loss during normal cooking can be maintained within a range where it does not become excessive. The ratio of length to width can be selected within this range depending on the size of the segment (311) and the required adjustment sensitivity, and is not limited to a specific value.

[0181] In one aspect of the present invention, the self-regulating ballast (330) may have a constant resistance temperature coefficient characteristic in which resistance increases continuously with rising temperature without involving a Curie transition. Unlike the behavior in which resistance jumps sharply at a specific temperature, the metal forming the ballast stripe (331) may have resistance that increases gradually and slowly as the temperature rises, and this gradual increase in resistance may act to gradually reduce the current flowing through the segment (311) without abrupt interruption.

[0182] In one embodiment, such a gentle constant resistance temperature coefficient characteristic does not substantially hinder power supply to the graphene heating layer (120) in the normal cooking temperature range, but when the temperature of a specific segment (311) rises locally, it may appear in a form that increases the resistance of the power supply connection part of that segment (311) to reduce the current flow. The segment (311) with a low temperature has a small change in resistance and continues to be supplied with power, while the segment (311) with a high temperature may have increased resistance and reduced current.

[0183] For example, the ballast stripe (331) may have a resistance increase rate of 10 to 60% per 100°C of temperature rise. The resistance increase rate can be determined by measuring the resistance between the two ends of the ballast stripe (331) at different temperatures and converting the increase into a temperature rise rate. If the resistance increase rate is 10% or more, the suppression of current flow regarding local temperature rise can be effectively achieved, and if it is 60% or less, the power supply can be maintained within a range where it is not excessively suppressed in the normal cooking temperature range. This resistance increase rate can be adjusted according to the shape and material of the ballast stripe (331) and is not limited to a specific value.

[0184] In one aspect of the present invention, a self-regulating ballast (330) arranged in series at the power supply connection of each segment (311) may be formed to include a constant temperature coefficient characteristic element. The constant temperature coefficient characteristic element is an element having a characteristic in which resistance increases significantly at a specific temperature range, and unlike a method in which resistance increases gradually with rising temperature, it can limit overheating of the segment (311) by clearly suppressing current flow at an effective transition temperature range.

[0185] In one embodiment, the effective transition temperature range of the constant temperature coefficient characteristic element can be selected to be located in the window between the top of the normal cooking temperature range and the safety upper limit. Since current flow may be suppressed during normal cooking if the effective transition temperature range is lower than the cooking temperature range, and overheat suppression may be delayed if it is higher than the safety upper limit, the effective transition temperature range can be located in the range between them. The constant temperature coefficient characteristic element can be discretely arranged in segments (311), thereby alleviating the burden when continuously forming a brittle element over the entire curved surface.

[0186] For example, the effective transition temperature range of the constant temperature coefficient characteristic element may be 200 to 320°C. As the constant temperature coefficient characteristic element, a ceramic having constant temperature coefficient characteristics may be used, and barium titanate (BaTiO3)-based ceramics may be an example, but is not limited to a specific material. The effective transition temperature range can be identified as the temperature range where the resistance begins to increase significantly by measuring the resistance of the constant temperature coefficient characteristic element at different temperatures.

[0187] In one aspect of the present invention, the effective transition temperature range of the constant temperature coefficient characteristic element may be limited to a narrower range within the aforementioned range. The narrower the effective transition temperature range is set, the closer the temperature at which current suppression is initiated can be aligned to the window between the top of the cooking temperature range and the safety upper limit.

[0188] In one embodiment, if the effective transition temperature range is set to a narrow range, it can act in a way that reduces both the unnecessary suppression of current flow and the delay of overheating suppression in the normal cooking temperature range.

[0189] For example, the effective transition temperature range of the positive temperature coefficient characteristic element may be 230 to 280°C. This range may correspond to a window before reaching a temperature at which the material or food is damaged, while exceeding the upper end of the general cooking temperature range.

[0190] In one aspect of the present invention, the effective transition temperature range of the constant temperature coefficient characteristic element may be further limited within the aforementioned narrow range. By limiting the effective transition temperature range in this way, the temperature at which current suppression begins is concentrated near the upper end of the cooking temperature range, so that the window for suppressing overheating without interfering with normal cooking can be narrowly adjusted.

[0191] In one embodiment, during normal cooking, the constant temperature coefficient characteristic element does not suppress current flow in the effective transition temperature range of this range, but can operate in a manner that suppresses current flow when the temperature of the segment (311) exceeds the upper limit of the cooking temperature range.

[0192] For example, the effective transition temperature range of the constant temperature coefficient characteristic element may be 250 to 260°C. This range corresponds to a narrow window between the normal cooking temperature range and the safety upper limit, and can be secured by adjusting the composition and composition ratio of the constant temperature coefficient characteristic element.

[0193] In one aspect of the present invention, a compensation conductive network (610) may be combined with the graphene heating layer (120). The compensation conductive network (610) is a conductive fiber network formed by intertwining a plurality of conductive fibers (611), and can form a conduction path through inter-fiber contact points (612) where the conductive fibers (611) meet each other. The compensation conductive network (610) may be placed overlapping the surface of the graphene heating layer (120) to form a conduction path parallel to the graphene heating layer (120).

[0194] In one embodiment, when the graphene heating layer (120) is locally stretched and thinned, the sheet resistance at that point may increase. The compensating conductive network (610) may be arranged such that the fiber contact points (612) are rearranged at the point of greater elongation to increase the parallel conduction path. Accordingly, even if the sheet resistance of the graphene heating layer (120) increases at the curved portion (212) of greater elongation, the compensating conductive network (610) can compensate for the increase in local resistance by supplementing the parallel path at that location, and the current path may be mitigated from bypassing that point.

[0195] For example, the compensation conductive network (610) can be combined with the graphene heating layer (120) at a density near the conduction threshold, and in the flat portion, it may exhibit a sheet resistance that matches the graphene heating layer (120) so as not to monopolize the current in the normal portion. This density can be controlled by the content of the conductive fibers (611), and can be verified by the degree of matching the sheet resistance of the flat portion with the sheet resistance of the graphene heating layer (120). The density of the compensation conductive network (610) can be selected in a range where parallel paths are supplemented only during elongation without monopolizing the conduction path in the flat portion. The compensation conductive network (610) may be placed within each segment (311) so as not to conduct between the segments (311).

[0196] In one aspect of the present invention, a complete insulation gap (320) formed at the boundary between segments (311) can penetrate and cut off the graphene heating layer (120) and the compensation conductive network (610) together. If only the graphene heating layer (120) is insulated and the compensation conductive network (610) extends beyond the boundary, the current suppressed in one segment (311) can bypass through the compensation conductive network (610) to the neighboring segment (311), so it may be required that the complete insulation gap (320) cut off both layers together.

[0197] In one embodiment, as the complete insulation gap (320) penetrates the graphene heating layer (120) and the compensation conductive network (610) together, the compensation conductive network (610) may exist only within each segment (311) and may not be conductively connected to adjacent segments (311) beyond the complete insulation gap (320). This allows the in-plane current interruption between segments (311) to be maintained for both the graphene heating layer (120) and the compensation conductive network (610).

[0198] For example, a complete insulation gap (320) can be formed as a boundary penetrating both layers together for a graphene heating layer (120) combined with a compensation conductive network (610), and electrical separation between segments (311) can be achieved through this boundary as shown in FIG. 4. Inside each segment (311), the graphene heating layer (120) and the compensation conductive network (610) are connected without interruption, and can be separated only between segments (311) by the complete insulation gap (320).

[0199] In one aspect of the present invention, the graphene heating layer (120) may be supported on both sides by an insulating layer (130) and an insulating protective layer (140) disposed on the opposite side of the insulating layer (130). Even if a compensation conductive network (610) is composited with the graphene heating layer (120), the graphene heating layer (120) and the compensation conductive network (610) may be supported together by a continuous support surface formed by the insulating layer (130) and the insulating protective layer (140) without having a separate carrier such as a porous grid.

[0200] In one embodiment, as the insulating layer (130) and the insulating protective layer (140) form continuous support surfaces on both sides of the graphene heating layer (120), the graphene heating layer (120) combined with the compensation conductive network (610) can behave in a state where both sides are supported even during a molding process including a curved portion (212). As the support surfaces are continuous, local lifting or sliding of the graphene heating layer (120) and the compensation conductive network (610) during molding can be suppressed.

[0201] For example, as shown in FIG. 4, a graphene heating layer (120) and a compensating conductive network (610) may be interposed between an insulating layer (130) and an insulating protective layer (140) and supported by continuous support surfaces on both sides. In this supported state, the compensating conductive network (610) may operate together with the graphene heating layer (120) even at points of large elongation and can supplement parallel conduction paths.

[0202] In one aspect of the present invention, the conductive material forming the compensation conductive network (610) may be made of a material that does not contain low-melting point metals and heavy metals. Since the cooking utensil is expected to come into repeated contact with food in a high-temperature environment, the conductive material of the compensation conductive network (610) may be selected from a material that does not contain low-melting point metals that are prone to melting at repeated high temperatures and heavy metals that are required to be excluded for food safety.

[0203] In one embodiment, by excluding low-melting-point metals, the shape of the conductive fibers (611) and the arrangement of the contact points (612) between fibers are maintained in the compensating conductive network (610) even with repeated heating, so that the behavior of supplementing parallel conductive paths in response to elongation can be maintained even during repeated use. By excluding heavy metals, safety in the cooking environment where food comes into contact can be ensured.

[0204] For example, a conductive material that is stable to repeated high temperatures and food contact may be used as the conductive material of the compensation challenge network (610), and such a conductive material may be selected from a class that does not include low-melting point metals and heavy metals and is not limited to a specific material.

[0205] FIG. 2 shows a perspective view of a cooking appliance (200) according to another aspect of the present invention, in which a detachable handle (400) is electrically connected. In FIG. 2, the main body (210) of the cooking appliance is shown as a molded body comprising a cooking surface portion (211) for holding food, a curved portion (212) extending upward from the circumference of the cooking surface portion (211), and a rim (213) forming the top of the curved portion (212). A detachable part (560) is provided on one side of the rim (213), and an electric contact (540) is disposed on the surface thereof. A detachable handle (400) separated from the detachable part (560), a handle-side contact (410) provided at the tip of the detachable handle (400) and connected to the electric contact (540), a switch (420) provided on the detachable handle (400), and an outgoing wiring (550) extending along the inside of the rim (213) to the electric contact (540) are shown together. In the following description, the reference numerals indicated in FIG. 2 are used for each component regarding the cooking appliance (200) and the detachable handle (400).

[0206] In another aspect of the present invention, the cooking appliance (200) may include a cooking appliance body (210) made of a molded body of a heating-type clad metal material (100) in which a plurality of layers are laminated and integrated, comprising a metal layer (110), a graphene heating layer (120) that generates resistive heat by electrical conduction, and an insulating layer (130) interposed between the graphene heating layer (120) and the metal layer (110) to block direct contact between the two. As the cooking appliance body (210) is made of such a molded body of a heating-type clad metal material (100), the cooking appliance body (210) itself can be heated by the resistive heat of the graphene heating layer (120) without relying solely on an external heat source.

[0207] In one embodiment, the cooking appliance body (210) may be a molded body formed by bending or pressing a heating-type clad metal material (100), and in this case, multiple layers of the heating-type clad metal material (100) may behave as a single unit without being separated from each other, thereby maintaining a stacking relationship even in the molded shape. In the cooking appliance body (210), electric heating by a graphene heating layer (120) and heat diffusion by a metal layer (110) may be provided together, and an insulating layer (130) may be formed to partition the space between the graphene heating layer (120) and the metal layer (110), so that the heat from the graphene heating layer (120) can be transferred to the cooking surface (211) side without loss due to bonding with the metal.

[0208] For example, the cooking utensil body (210) can be molded into a shape including a cooking surface (211) in which food is placed and a curved surface (212) extending around it, and can form a pan or shallow wok shape as shown in FIG. 2. The cooking utensil body (210) can raise the temperature of the cooking surface (211) by energizing the graphene heating layer (120) even in an environment where a separate heating source is not provided.

[0209] In one aspect of the present invention, the cooking utensil body (210) may be a molded body in the shape of a frying pan, wok, or pot including a curved portion (212). Even if the cooking utensil body (210) is molded into a shape including a deep curved portion, the graphene heating layer (120) may provide resistance heating continuously and without interruption throughout the entire molded shape of the cooking utensil body (210).

[0210] In one embodiment, as the graphene heating layer (120) is continuous without interruption across the cooking surface (211) and the curved surface (212), heating occurs not only on the cooking surface (211) forming the bottom but also on the curved surface (212) forming the side wall, so that the entire surface where food comes into contact can be heated evenly. Even in the shape of a wok or pot with a deep curved surface (212), the heating can extend to the side wall rather than being concentrated only on the bottom.

[0211] For example, the cooking utensil body (210) can be formed into a frying pan shape as shown in FIG. 2, or a wok or pot shape with deep side walls, and is not limited to a specific shape.

[0212] In another aspect of the present invention, the cooking appliance (200) may include a cooking appliance body (210) made of a molded body of a heating-type clad metal material (100), an electrical contact (540) electrically connected to a graphene heating layer (120) and extended toward the edge (213) of the cooking appliance body (210), and a detachable handle (400) detachably coupled to the electrical contact (540) and energizing the graphene heating layer (120). Since energization to the graphene heating layer (120) is achieved by the detachment of the detachable handle (400), when the detachable handle (400) is removed, an open energization path may remain on the cooking appliance body (210) side.

[0213] In one embodiment, the electric contact (540) may be drawn out from the graphene heating layer (120) toward the edge (213) of the cooking appliance body (210) and positioned at the location where the detachable handle (400) is attached, and when the detachable handle (400) is attached to the electric contact (540), current may be supplied to the graphene heating layer (120) through the detachable handle (400). Referring to FIG. 5, the current path from the graphene heating layer (120) to the electric contact (540) toward the edge (213) may be drawn out through the interior of the cooking appliance body (210).

[0214] For example, the detachable handle (400) can be connected such that the handle-side contact (410) at its tip is connected to an electric contact (540), and when the detachable handle (400) is removed after cooking, only the main body of the cooking appliance (210) can be washed or stored. Since power is supplied through the detachable handle (400), a separate control unit for power supply can be provided on the main body of the cooking appliance (210).

[0215] In one aspect of the present invention, the cooking appliance (200) may further include a power supply electrode (busbar) (500) connected to both ends of a graphene heating layer (120), and an electrical connection wire (550) drawn from the power supply electrode (busbar) (500) to a detachable part (560) on the edge (213) side of the cooking appliance body (210). As the power supply electrode (busbar) (500) is connected to both ends of the graphene heating layer (120) and the wire (550) is extended from thereto toward the edge (213) side, the current path of the graphene heating layer (120) may be extended to the detachable part (560).

[0216] In one embodiment, an electric contact (540) is positioned in the detachable part (560) so that it can be connected to the handle side contact (410) when the detachable handle (400) is attached to the detachable part (560). Referring to FIG. 5, a wire (550) drawn from the power supply electrode (busbar) (500) can pass through the inside of the rim (213) and extend to the electric contact (540) of the detachable part (560).

[0217] For example, the wire (550) drawn out to the detachable part (560) can form a path connecting the power supply electrode (busbar) (500) connected to the graphene heating layer (120) and the handle side contact (410) of the detachable handle (400), and when the detachable handle (400) is coupled to the detachable part (560), power can be supplied to the graphene heating layer (120) through this path.

[0218] In one aspect of the present invention, the electrical contact (540) of the detachable part (560) may be connected in series with the handle-side contact (410) of the detachable handle (400). As the electrical contact (540) and the handle-side contact (410) are connected in series, the current path to the graphene heating layer (120) may be connected as a single path through the detachable handle (400).

[0219] In one embodiment, since the electric contact (540) and the handle side contact (410) are connected in series, when the detachable handle (400) is separated, the path is cut off and no current is supplied, and when the detachable handle (400) is connected, the path is connected and current can be supplied.

[0220] For example, referring to FIG. 5, the electrical contact (540) of the detachable part (560) and the handle side contact (410) can be connected in series on the current path to the graphene heating layer (120).

[0221] In one aspect of the present invention, a switch (420) for opening and closing the current to the graphene heating layer (120) may be disposed on the side of the detachable handle (400), and the main body of the cooking appliance (210) may be provided with only an inactive electrical structure including an electrical contact (540) and an outgoing wire (550) connected to the electrical contact (540). Since the switch (420) for opening and closing the current is placed on the side of the detachable handle (400), an active element such as a switch or a control element may not be placed on the side of the main body of the cooking appliance (210).

[0222] In one embodiment, since no active element is placed in the cooking appliance body (210) and only a passive structure of an electrical contact (540) and an outgoing wire (550) is provided, the cooking appliance body (210) can be washed or heated with the detachable handle (400) removed. The opening and closing of the power supply can be done at the switch (420) on the detachable handle (400).

[0223] For example, the switch (420) may be in the form of a button or lever placed on the upper surface or side of the detachable handle (400), and may be operated from the side of the detachable handle (400) as shown in FIG. 2. The wiring (550) leading to the cooking appliance body (210) may be extended only to the electrical contact (540), leaving only a passive structure forming a power path in the cooking appliance body (210).

[0224] In one aspect of the present invention, the graphene heating layer (120) comprises a plurality of segments (311) that are divided along the power supply direction and connected in parallel with each other, and a self-regulating ballast (330) that reduces the current flow according to the temperature rise of the corresponding segment (311) is arranged in series at the power supply connection portion of each of the plurality of segments (311), and a switch (420) that opens and closes the power flow to the graphene heating layer (120) may be arranged on the side of the detachable handle (400). As the self-regulating ballast (330) for each segment (311) controls the power flow on the layer of the graphene heating layer (120) forming the heat source, and the switch (420) opens and closes the power flow on the side of the detachable handle (400), two means for restricting power flow at different locations may be provided together.

[0225] In one embodiment, the self-regulating ballast (330) can operate as a passive material that reduces the current flowing through the segment (311) according to the temperature of the segment (311), and the switch (420) can open and close the current flow on the side of the detachable handle (400). Since the current restriction on the heat source layer by the self-regulating ballast (330) can operate independently of the opening and closing of the switch (420) on the side of the detachable handle (400), the current restriction on the other side can be maintained regardless of the current restriction on one side.

[0226] For example, the segment-specific self-regulating ballast (330) shown in FIG. 3 and the detachable handle (400) side switch (420) shown in FIG. 5 can be arranged to restrict current flow at different locations on the heat source layer and the handle side, respectively. Since the self-regulating ballast (330) on the heat source layer operates on a segment-specific (311) basis without a sensing element or controller, it can form a structure that restricts current flow at different locations together with the detachable handle (400) side switch (420).

[0227] The present disclosure will be explained in detail below through specific embodiments and experimental examples. However, the following embodiments are intended to illustrate the present disclosure and the scope of the present disclosure is not limited thereto.

[0228] Example 1

[0229] The heating-type clad metal material consists of an integrated clad plate comprising approximately five layers, in which a cooking surface-side metal layer, a thermal diffusion metal layer, a dielectric interlayer, a graphene heating layer, an insulating protective layer, and an outer metal layer are stacked in sequence from the cooking surface side. The cooking surface-side metal layer is stainless steel, the outer metal layer is magnetic stainless steel which is a magnetic metal layer corresponding to an induction heating source, and the thermal diffusion metal layer is aluminum, which has heat transfer approximately three times faster than stainless steel, and diffuses heat from the inner side in the thickness direction of the plate. The graphene heating layer has a thickness of approximately 0.25 nanometers and is composed of graphene, which has a tensile strength approximately 200 times that of iron, and generates resistive heating upon electrical conduction. The dielectric interlayer is made of a ceramic possessing both electrical insulation and thermal conductivity, has a thickness of 50 micrometers, and a thermal conductivity of approximately 10 W / m·K. It is interposed on the side of the sintering surface of the graphene heating layer to electrically insulate the graphene heating layer from the metal layer on the sintering surface side while transferring heat from the graphene heating layer to the sintering surface side. The insulating protective layer is in contact with the outer surface of the graphene heating layer to insulate it from the outer metal layer, and the graphene heating layer is electrically insulated from the adjacent metal layer on both sides. The opposing ends of the graphene heating layer are exposed and extended to the edge of the plate to form exposed ends. Power supply electrodes (busbars) are formed at each exposed end to conduct current across the entire surface of the graphene heating layer, and an insulating sleeve surrounds the exposed ends to insulate the power supply electrodes (busbars) from the adjacent metal layer and pull them out toward the edge of the plate. The power supply electrodes (busbars) have a rated power supply voltage of approximately 220 V and a surface power density of approximately 5 to 8 W / cm². 2Power is supplied to the graphene heating layer under the condition of.

[0230] Example 2

[0231] It follows the same stacking order and feed structure as Example 1, but the dielectric interlayer is made of polyimide instead of ceramic and has a thickness of 50 micrometers.

[0232] Example 3

[0233] The invention comprises three types of plates manufactured in the same manner as Example 1, wherein the thickness of the dielectric interlayer is varied to 40 micrometers, 50 micrometers, and 60 micrometers, respectively, and an additional metal layer made of copper that accelerates heat transfer is further laminated on the metal layer on the side of the metal layer on the side of the metal layer.

[0234] Example 4

[0235] It includes two types of plates manufactured in the same manner as Example 1, but with different thicknesses of dielectric interlayers of 80 micrometers and 150 micrometers, respectively.

[0236] Example 5

[0237] The dielectric interlayer is manufactured in the same manner as in Example 1, but with a dielectric interlayer thickness of 50 micrometers and two types of electrical insulating materials having different thermal conductivity of approximately 6 W / m·K and approximately 14 W / m·K, respectively, and each dielectric interlayer has a thickness greater than or equal to a lower thickness limit having an dielectric breakdown voltage greater than or equal to the feed voltage applied to the feed electrode (busbar).

[0238] Example 6

[0239] The cooking utensil is formed by deep drawing the plate material of Example 1 into a molded body in the shape of a frying pan with a diameter of 24 cm. An anchoring protrusions are formed at the interface between the dielectric interlayer and the graphene heating layer to mechanically engage the graphene heating layer with the dielectric interlayer, and an adhesive primer layer is interposed at the interface to mediate the adhesion between the graphene heating layer and the dielectric interlayer. The graphene heating layer engages with the anchoring protrusions throughout the entire molded body, including the curved portion, and remains continuous without interruption.

[0240] Example 7

[0241] The molding is performed in the same manner as in Example 6, but is formed into a wok-shaped molded body, and includes three types of molded bodies in which the thickness of the graphene heating layer on the curved portion is 50%, 70%, and 85% of the thickness on the flat portion by varying the anchoring and molding conditions.

[0242] Example 8

[0243] In the molded body of Example 7, the graphene heating layer is formed on a curved portion and has a strain-relief shape that disperses molding stress and thermal expansion stress, and the strain-relief shape includes at least one of a divided portion, a wrinkled portion, and a recessed portion formed in the graphene heating layer.

[0244] Example 9

[0245] The cooking appliance comprises a cooking appliance body made of the molded body of Example 6 and a detachable handle. An electrical contact is drawn from a power supply electrode (busbar) connected to both ends of the graphene heating layer to a detachable part on the edge side of the cooking appliance body, and an electrical contact is disposed on the detachable part. The detachable handle is detachably coupled to the detachable part, and when the detachable handle is coupled to the detachable part, the electrical contact of the detachable part is connected in series with the contact on the detachable handle side to conduct electricity to the graphene heating layer. A switch for opening and closing the conduction to the graphene heating layer is disposed on the detachable handle side, and the cooking appliance body is provided with only an inactive electrical structure including an electrical contact and a wire drawn out from the electrical contact.

[0246] Example 10

[0247] The heating clad metal material is based on the stacked structure of Example 1 and includes a first feed electrode (busbar) and a second feed electrode (busbar) spaced apart from each other in the graphene heating layer. The graphene heating layer includes a plurality of stripe-shaped segments divided along the feed direction in which current flows between the first feed electrode (busbar) and the second feed electrode (busbar), and the plurality of segments are each connected in parallel to the first feed electrode (busbar) and the second feed electrode (busbar) to be supplied in parallel with a constant voltage of approximately 220 V. A complete insulation gap is formed at the boundary between the plurality of segments to block in-plane current flow between adjacent segments, and the complete insulation gap is arranged in an interdigital shape so that the heating areas of adjacent segments interlock with each other in projection onto the aperture plane, and the graphene heating layer is continuous without interruption within each of the plurality of segments and is electrically separated only from each other by the complete insulation gap. In the power supply connection portion of each of the multiple segments, a self-regulating ballast consisting of ballast stripes patterned with clad metal in a long, narrow, fine parallel stripe with a length-to-width ratio is arranged in series, and as the temperature of the segment rises, the resistance increases, thereby reducing the current flowing through the segment.

[0248] Example 11

[0249] It is manufactured in the same manner as Example 10, but is in the shape of a plurality of tiles in which a plurality of segments are arranged two-dimensionally along the plane of the graphene heating layer.

[0250] Example 12

[0251] The three types of materials are manufactured in the same manner as in Example 10, but with the ratio of length to width of the ballast stripes varying to 8, 30, and 80, respectively, and each self-regulating ballast has a constant resistance temperature coefficient characteristic in which resistance increases continuously with temperature rise without Curie transition, and the resistance increase rate per 100°C of temperature rise is approximately 15%, 35%, and 55%, respectively.

[0252] Example 13

[0253] Manufactured in the same manner as Example 10, but the self-regulating ballast includes a positive temperature coefficient characteristic element, and the positive temperature coefficient characteristic element is made of a barium titanate (BaTiO3)-based ceramic and includes three types with effective transition temperature ranges of approximately 250°C, 255°C, and 260°C, respectively, a type with approximately 270°C, and a type with approximately 310°C.

[0254] Example 14

[0255] The device is manufactured in the same manner as in Example 10, but a compensating conductive network is composited with the graphene heating layer, confined to the interior of each of the plurality of segments. The compensating conductive network is a conductive fiber network arranged such that contact points between fibers are rearranged upon elongation to increase parallel conduction paths. It is composited with a density near the conduction threshold that exhibits a sheet resistance matching the graphene heating layer in the flat portion, and includes two types with densities approximately 1.0 times and approximately 1.1 times the conduction threshold, respectively. The complete insulation gap at the segment boundary penetrates and disconnects the graphene heating layer and the compensating conductive network together, and the graphene heating layer is supported on both sides by a continuous support plane formed by a dielectric interlayer and an insulating protective layer. The compensating conductive network is composed of a conductive material that does not contain low-melting-point metals or heavy metals.

[0256] Example 15

[0257] The cooking utensil comprises a wok-shaped cooking utensil body having a detachable electrical connection structure of Example 9 and a detachable handle. The graphene heating layer of the cooking utensil body comprises a plurality of segments that are divided along the power supply direction and connected in parallel with one another as in Example 10, and a magnetic control ballast is arranged in series at the power supply connection part of each of the plurality of segments to reduce the current flowing according to the temperature rise of the corresponding segment. A switch is arranged on the side of the detachable handle to open and close the current flowing to the graphene heating layer, so that the magnetic control ballast on the side of the heating source and the switch on the side of the detachable handle control the current flowing independently of each other.

[0258] Comparative Example 1

[0259] The heating type clad metal material has the same layer configuration as Example 1 but does not have a dielectric interlayer, and the graphene heating layer is in direct contact with an adjacent metal layer so that a conductive path is formed between the graphene heating layer and the metal layer.

[0260] Comparative Example 2

[0261] It is manufactured in the same manner as Example 1, but the thickness of the dielectric interlayer is about 8 micrometers.

[0262] Comparative Example 3

[0263] It is manufactured in the same manner as Example 1, but the thickness of the dielectric interlayer is about 250 micrometers.

[0264] Comparative Example 4

[0265] It is manufactured in the same manner as Example 1, but the thermal conductivity of the dielectric interlayer is approximately 3 W / m·K.

[0266] Comparative Example 5

[0267] It is manufactured in the same manner as Example 1, but the dielectric interlayer is made of an electrically conductive material with a thermal conductivity of about 20 W / m·K, so that a conductive path is formed between the graphene heating layer and the adjacent metal layer.

[0268] Comparative Example 6

[0269] Molded in the same manner as Example 7, but the thickness of the graphene heating layer in the curved portion is about 40% of the thickness in the flat portion.

[0270] Comparative Example 7

[0271] Molding is performed in the same manner as in Example 6, but without forming an anchoring irregularity and an adhesive primer layer at the interface between the dielectric interlayer and the graphene heating layer, and without forming a strain-relief shape on the graphene heating layer, and delamination and cracks are formed on the graphene heating layer at the curved portion by molding.

[0272] Comparative Example 8

[0273] Manufactured in the same manner as Example 10, but the graphene heating layer is formed as a single continuous heating film without dividing it into multiple segments, and a single self-regulating ballast is arranged in series at the power supply connection portion of the entire heating film.

[0274] Comparative Example 9

[0275] Manufactured in the same manner as Example 10, but with conductive bridges placed at the boundaries between multiple segments instead of complete insulation gaps so that an in-plane conductive path is formed between adjacent segments.

[0276] Comparative Example 10

[0277] Manufactured in the same manner as Example 10, but the plurality of segments are supplied with constant current instead of constant voltage parallel supply.

[0278] Comparative Example 11

[0279] It is manufactured in the same manner as Example 12, but includes two types in which the ratio of the length to the width of the ballast stripe is approximately 3 and approximately 120, respectively.

[0280] Comparative Example 12

[0281] It is manufactured in the same manner as Example 12, but includes two types in which the resistance increase rate per 100°C of the temperature rise of the self-regulating ballast is approximately 5% and approximately 80%, respectively.

[0282] Comparative Example 13

[0283] It is manufactured in the same manner as Example 13, but includes two types in which the effective transition temperature range of the positive temperature coefficient characteristic element is approximately 180°C and approximately 350°C, respectively.

[0284] Comparative Example 14

[0285] It is manufactured in the same manner as Example 14, but includes two types in which the density of the compensation challenge network is approximately 0.8 times and approximately 1.3 times the conduction threshold, respectively.

[0286] Comparative Example 15

[0287] Manufactured in the same manner as Example 14, but with the complete insulation gap penetrating only the graphene heating layer and not the compensation conductive network, so that the compensation conductive network extends beyond the segment boundary to the adjacent segment, forming a conductive path between the segments.

[0288] Comparative Example 16

[0289] Manufactured in the same manner as Example 14, but the compensation conductive network is composed of a conductive material including a low-melting point metal and a heavy metal.

[0290] Experimental Example 1

[0291] For the plates of Examples 3 and 4 and Comparative Examples 2 and 3, the heating rate of the cooking surface was measured by applying a power supply voltage of approximately 220 V while varying the thickness of the dielectric interlayer from 8 micrometers to 250 micrometers, and the dielectric breakdown voltage was measured according to KS C IEC 60243, and the results are as shown in Table 1.

[0292] Dielectric interlayer thickness (micrometers) Heating rate (°C / s) Dielectric breakdown voltage (kV) 8 insulation breakdown 0.16 20 2.9 0.40 35 2.7 0.70 40 2.6 0.80 50 2.4 1.00 60 2.2 1.20 65 2.15 1.30 80 1.95 1.60 100 1.7 2.00 150 1.25 3.00 250 0.85 5.00

[0293] Comparative Example 2, with a thickness of 8 micrometers, has an dielectric breakdown voltage of approximately 0.16 kV, which is lower than the power supply voltage of approximately 220 V, so the insulation breaks down when power is supplied, and Comparative Example 3, with a thickness of 250 micrometers, has a heating rate of 0.85 ℃ / s. Example 3, with a dielectric interlayer thickness of 40 to 60 micrometers, has a heating rate of 2.2 to 2.6 ℃ / s and a dielectric breakdown voltage of 0.80 to 1.20 kV, and Example 4, with thicknesses of 80 micrometers and 150 micrometers, has a heating rate of 1.95 ℃ / s and 1.25 ℃ / s.

[0294] Experimental Example 2

[0295] Table 2 shows the results of measuring the time it takes for the cutting surface to reach the target temperature and whether insulation is maintained during power supply for the plates of Example 5 and Comparative Examples 4 and 5, while varying the thermal conductivity of the dielectric interlayer from 3 W / m·K to 20 W / m·K.

[0296] Thermal conductivity of dielectric interlayer (W / m·K) Time to reach target temperature(s) Whether insulation is maintained 3 55 maintain 6 42 maintain 10 35 maintain 14 31 maintain 20 Unreached insulation breakdown

[0297] Comparative Example 4, with a thermal conductivity of about 3 W / m·K, has a time to reach of 55 seconds, and Comparative Example 5, with a thermal conductivity of about 20 W / m·K, has a metal layer adjacent to the graphene heating layer that conducts and is destroyed. Example 5, with a thermal conductivity of 5 to 15 W / m·K, has a time to reach of 31 to 42 seconds and maintains insulation.

[0298] Experimental Example 3

[0299] For the plates of Examples 1 and 3, the temperature deviation of the cooking surface was measured using infrared thermal imaging while varying the presence or absence of a heat-diffusing metal layer, an additional metal layer that accelerates heat transfer, and an outer magnetic metal layer, and the results of measuring the heating rate in a gas heating source and an induction heating source are as shown in Table 3.

[0300] Layer composition Cooking surface temperature deviation ΔT(℃) Gas heating rate (°C / s) Induction heating rate (°C / s) No thermal diffusing metal layer · Non-magnetic outer layer 48 2.0 No power supply Contains thermal diffusing metal layer · Non-magnetic outer layer 22 2.3 No power supply There is a thermal diffusion metal layer and an additional metal layer that accelerates heat transfer. 15 2.6 No power Contains thermal diffusion metal layer · magnetic outer layer 21 2.3 2.2

[0301] When a heat-diffusing metal layer is not provided, the cooking surface temperature difference is 48°C, when a heat-diffusing metal layer made of aluminum is provided, the cooking surface temperature difference is 22°C, and when an additional metal layer made of copper that accelerates heat transfer is provided on the cooking surface side, the cooking surface temperature difference is 15°C and the gas heating rate is 2.6°C / s. When the outer metal layer is a magnetic metal layer, the heating rate in the induction heating source is 2.2°C / s.

[0302] Experimental Example 4

[0303] Table 4 shows the results of measuring the rate of increase in local resistance in the curved portion and the temperature rise of the hot spot in the curved portion relative to the flat portion for the molded bodies of Examples 7 and 8 and Comparative Examples 6 and 7, while varying the thickness ratio of the graphene heating layer in the curved portion from 40% to 90%. The thickness of the heating layer was measured using a cross-sectional scanning electron microscope.

[0304] Curved / Flat Thickness Ratio (%) Local resistance increase rate (no strain relief, %) Local resistance increase rate (with strain-relief, %) Hotspot temperature rise (°C) 40 150 118 95 50 90 62 60 60 55 35 38 70 30 17 22 75 22 12 16 85 12 6 9 90 8 4 6

[0305] Comparative Example 6, with a thickness ratio of approximately 40%, has a local resistance increase rate of 150% and a hot spot temperature increase of 95°C. Comparative Example 7, which does not have anchoring irregularities and strain-relief shapes, has a graphene heating layer peeled off and disconnected at the curved surface, thereby severing the current path in that area. Example 7, with a thickness ratio of 50% or more, 70% or more, and 85% or more, has a local resistance increase rate of 90%, 30%, and 12%, respectively, when it does not have a strain-relief shape, and Example 8, which has a strain-relief shape, has a local resistance increase rate of 62%, 17%, and 6%, respectively, at the same thickness ratio.

[0306] Experimental Example 5

[0307] Table 5 shows the results of measuring the in-plane temperature deviation of the heating surface using infrared thermal imaging while applying local heating to a part of the heating surface for the material of Example 10 and the materials of Comparative Examples 8, 9, and 10.

[0308] Supply and boundary configuration In-plane temperature deviation ΔT(℃) Continuous heating film · Single ballast (Comparative Example 8) 42 Segment matrix · Segment-specific ballast (Example 10) 11 Segment matrix · conductive bridge boundary (Comparative Example 9) 33 Segment matrix · constant current supply (Comparative Example 10) 51

[0309] Example 10, in which a segment matrix and a segment-specific self-regulating ballast are supplied in parallel with a constant voltage, has an in-plane temperature deviation of 11°C. Comparative Example 8, in which a single ballast is placed on a continuous heating film, has a deviation of 42°C, Comparative Example 9, in which a conductive bridge is placed at the segment boundary, has a deviation of 33°C, and Comparative Example 10, in which the segments are supplied with a constant current, has a deviation of 51°C.

[0310] Experimental Example 6

[0311] Table 6 shows the results of measuring the current suppression rate when the temperature of the segment increases by 100°C and the normal resistance loss at normal cooking temperature for the materials of Example 12 and Comparative Examples 11 and 12, while varying the ratio of length to width of the ballast stripe and the resistance increase rate per 100°C increase in temperature. The resistance and resistance temperature coefficient were measured using the four-terminal method in a constant temperature bath at 25°C to 300°C.

[0312] shape ratio Resistance increase rate (% / 100℃) Current suppression rate (%) Constant resistance loss I 2 R(W) 3 5 8 2 8 15 18 5 30 35 33 9 80 55 52 16 120 80 60 28

[0313] Comparative Examples 11 and 12, in which the aspect ratio is about 3 and the resistance increase rate is about 5%, have a current suppression rate of 8%, and in the case where the aspect ratio is about 120 and the resistance increase rate is about 80%, the normal resistance loss is 28 W. Example 12, in which the aspect ratio is 5 to 100 and the resistance increase rate is 10 to 60%, has a current suppression rate of 18% to 52% and a normal resistance loss of 5 W to 16 W.

[0314] Experimental Example 7

[0315] Table 7 shows the results of measuring the power supply obstruction degree at the response temperature at which power is cut off upon overheating and at the normal cooking temperature range of about 180 to 240°C for the materials of Example 13 and Comparative Example 13, while varying the effective transition temperature range of the constant temperature coefficient characteristic element from 180°C to 350°C.

[0316] Effective transition temperature range (°C) Overheat cutoff response temperature (°C) Normal cooking power supply obstruction (%) 180 180 45 250 250 3 255 255 2 260 260 1.5 270 270 1.0 310 310 0.4 350 Not blocked 0.2

[0317] Comparative Example 13, with an effective transition temperature range of about 180°C, has a power supply obstruction of 45% at a normal cooking temperature range, and Comparative Example 13, with an effective transition temperature range of about 350°C, does not cut off power supply even when overheated. Example 13, with an effective transition temperature range of 250 to 260°C, has a power supply obstruction of 1.5% to 3% and an overheat cutoff response temperature of 250 to 260°C, and Example 13, with effective transition temperature ranges of 270°C and 310°C, has power supply obstruction of 1.0% and 0.4%, respectively.

[0318] Experimental Example 8

[0319] Table 8 shows the results of measuring the sheet resistance of the graphene heating layer alone and the sheet resistance of the combined compensating conductive network with the material of Example 14 and the materials of Comparative Examples 14, 15, and 16 using a 4-point probe while applying a biaxial elongation strain of 0% to 15% in stages to the flat plate specimen.

[0320] Biaxial elongation strain ε(%) Graphene heating layer sheet resistance (Ω / sq) Compensated challenge network composite sheet resistance (Ω / sq) 0 30 31 2 38 31 5 55 30 10 95 29 15 150 28

[0321] For the graphene heating layer alone, the sheet resistance increases from 30 Ω / sq to 150 Ω / sq as the elongation strain increases from 0% to 15%, while for the case where a compensating conductive network with a density near the conduction threshold is combined, the sheet resistance remains at 31 Ω / sq to 28 Ω / sq in the same range. The results obtained by varying the density of the compensating conductive network to 0.8 to 1.3 times the conduction threshold are shown in Table 9.

[0322] Reward challenge network density (relative to conduction threshold) Normal surface resistance (Ω / sq) Stretch (ε 15%) Sheet resistance (Ω / sq) 0.8 times 33 90 1.0x 31 28 1.1 times 30 26 1.3 times 22 18

[0323] Comparative Example 14, with a density approximately 0.8 times the conduction threshold, has an elongated sheet resistance of 90 Ω / sq, and Comparative Example 14, with a density approximately 1.3 times the conduction threshold, has a normal sheet resistance of 22 Ω / sq, which is lower than the sheet resistance of the graphene heating layer. Example 14, with a density 1.0 to 1.1 times the conduction threshold, has a normal sheet resistance of 30 Ω / sq to 31 Ω / sq and an elongated sheet resistance of 26 Ω / sq to 28 Ω / sq. In the molded body with a wick shape, the deviation in current density of the curved surface is 12% for Example 14, which incorporates a compensating conductive network, and 47% for the case where the compensating conductive network is removed. In Example 14, where a complete insulation gap penetrates both the graphene heating layer and the compensation conductive network, the bypass current between segments is 0.02 A, and in Comparative Example 15, where a complete insulation gap penetrates only the graphene heating layer, the bypass current between segments is 3.5 A. In Example 14, which is made of a conductive material that does not contain low-melting point metals and heavy metals, lead, cadmium, and arsenic are each less than 0.01 mg / L in the leaching test according to the Standard for Food Utensils, Containers, and Packaging, and in Comparative Example 16, which is made of a conductive material that contains low-melting point metals and heavy metals, the heavy metal leaching amount exceeds 0.3 mg / L.

[0324] A person skilled in the art will obviously recognize that inventions having non-limiting additional purposes and / or effects under the technical spirit of this disclosure are also included within the scope of this disclosure, and that some of the components of this disclosure can be obviously substituted to form a concept including the technical spirit of this disclosure, and that omissions and / or additions can also be made without particular technical difficulty.

Claims

Claim 1 A heating clad metal material comprising: a metal layer; a graphene heating layer that generates resistive heat by electrical conduction; and an insulating layer interposed between the graphene heating layer and the metal layer to block direct contact between the graphene heating layer and the metal layer, wherein the metal layer, the insulating layer, and the graphene heating layer are laminated in a plurality of layers and integrated. Claim 2 A heating type clad metal material according to claim 1, further comprising an additional metal layer laminated on one surface in the direction in which the plurality of layers are laminated. Claim 3 A heat-generating clad metal material according to claim 1, wherein the metal layer comprises a plurality of metal layers, and the plurality of metal layers comprises a heat-diffusing metal layer that has faster heat transfer than the remaining metal layers and is disposed inward in the thickness direction of the plurality of layers to diffuse heat. Claim 4 A cooking appliance body comprising: a molded body of a heating-type clad metal material, wherein a plurality of layers are laminated and integrated, the metal layer, the graphene heating layer that generates resistive heat by electrical conduction, and the insulating layer interposed between the graphene heating layer and the metal layer to block direct contact between the graphene heating layer and the metal layer. Claim 5 A cooking appliance body comprising: a molded body of a heating-type clad metal material, wherein a plurality of layers are laminated and integrated, the metal layer, the graphene heating layer which generates resistive heat by electrical conduction, and the insulating layer which is interposed between the graphene heating layer and the metal layer to block direct contact between the graphene heating layer and the metal layer; an electrical contact electrically connected to the graphene heating layer and drawn out toward the edge of the cooking appliance body; and a detachable handle detachably coupled to the electrical contact and conducting electricity to the graphene heating layer. Claim 6 A cooking appliance according to claim 5, wherein a switch for opening and closing the conduction to the graphene heating layer is disposed on the side of the detachable handle, and the cooking appliance body is equipped only with an inactive electrical structure including the electric contact and the lead wiring connected to the electric contact.

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