Plate for cooking apparatus and cooking apparatus including same

Abstract

A plate for a cooking apparatus according to one embodiment of the present disclosure comprises: a black glass layer; and an uneven layer disposed on the glass layer, wherein the surface roughness (Ra) of the uneven layer is 2 to 4 um.

Description

Plate for cooking appliance and cooking appliance including the same

[0001] The present disclosure relates to a plate for a cooking appliance and a cooking appliance including the same, and more specifically, to a cooking appliance used to heat food by generating heat and a plate for a cooking appliance applied thereto.

[0002] Induction devices (induction heating devices) are used as devices to generate heat and heat food. In particular, cooktops (or hobs) are used as cooking appliances to heat food using induction devices.

[0003] Generally, ceramic glass with excellent heat resistance is used for the upper part of cooktops. Ceramic glass has excellent mechanical strength and thermal conductivity, and rarely experiences thermal shock fracture. However, when ceramic glass is applied to cooktops, it is continuously exposed to high-temperature environments and physical shocks, so properties such as mechanical strength and heat resistance are required. Therefore, various methods are being studied to improve properties such as mechanical strength and heat resistance.

[0004] According to one embodiment of the present disclosure, the purpose is to provide a plate for cooking appliances with improved strength, heat resistance, and scratch resistance, and a method for manufacturing the same. In addition, the present disclosure aims to provide a plate for cooking appliances with improved cleanability and aesthetics, and a method for manufacturing the same.

[0005] The technical problems to be solved in this document are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which this invention belongs from the description below.

[0006] A plate (200) for a cooking appliance according to an embodiment of the present disclosure comprises a glass layer (210) having a black color and an uneven layer (220) disposed on the glass layer (210), and the surface roughness (Ra) of the uneven layer (220) is 2 to 4 μm.

[0007] A method for manufacturing a plate for a cooking appliance according to an embodiment of the present disclosure comprises the steps of: manufacturing a ceramic glass precursor (S1); heating the ceramic glass precursor to form a crystal (S2); cooling the ceramic glass from which the crystal has been formed to form a glass layer (210) in the form of a substrate (S3); blasting at least one surface of the substrate (S4); first etching at least one surface of the blasted substrate to form an uneven layer (220) on the surface of the substrate (S5); polishing the surface of the substrate (S6); second etching at least one surface of the substrate from which the polishing is completed to remove impurities from the substrate (S7); and chemically strengthening at least one surface of the substrate from which the second etching is completed (S8), wherein the surface roughness of the surface of the substrate from which the chemical strengthening is completed is 2 to 4 μm.

[0008] A cooking device (1000) according to an embodiment of the present disclosure comprises a cooking device plate (200) having a black color on which a cooking container (CT) is placed, and a main body (100) disposed below the cooking device plate and including a plurality of heating coils, wherein the cooking device plate (200) comprises a glass layer (210) having heat resistance with a heat deformation temperature of 650°C or higher, and an uneven layer (220) disposed on the glass layer (210) and having a surface roughness (Ra) of 2 to 4 μm.

[0009] FIG. 1 is an overall perspective view of a cooking appliance according to one embodiment of the present disclosure.

[0010] Figure 2 is an exploded perspective view of the cooking appliance shown in Figure 1.

[0011] Figure 3 is a cross-sectional view of the line A-A' shown in Figure 2.

[0012] Figure 4 is an enlarged cross-sectional view of region B shown in Figure 3.

[0013] FIG. 5 is a flowchart of a method for manufacturing a cooking appliance according to one embodiment of the present disclosure.

[0014] FIG. 6 is a table showing the scratch visibility and the vertical force at the time of scratch occurrence according to the surface roughness and glossiness of the embodiments and comparative examples of the present disclosure.

[0015] The various embodiments of the present disclosure and the terms used therein are not intended to limit the technical features described in the present disclosure to specific embodiments, and should be understood to include various modifications, equivalents, or substitutions of said embodiments.

[0016] In relation to the description of the drawings, similar reference numerals may be used for similar or related components.

[0017] The singular form of the noun corresponding to the item may include one or multiple items, unless the relevant context clearly indicates otherwise.

[0018] In the present disclosure, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0019] The term “and / or” includes a combination of multiple related described components or any of the multiple related described components.

[0020] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish a component from another component and do not limit the components in other aspects (e.g., importance or order).

[0021] Additionally, terms such as 'front,' 'rear,' 'top,' 'bottom,' 'side,' 'left,' 'right,' 'top,' and 'bottom' used in this disclosure are defined based on the drawings, and the shape and location of each component are not limited by these terms.

[0022] Terms such as “include” or “have” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in this disclosure, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0023] When it is said that a component is "connected," "combined," "supported," or "in contact" with another component, this includes not only cases where the components are directly connected, combined, supported, or in contact, but also cases where they are indirectly connected, combined, supported, or in contact through a third component.

[0024] When it is said that a component is located "on" another component, this includes not only cases where one component is in contact with the other, but also cases where another component exists between the two components.

[0025] Hereinafter, a plate for a cooking appliance and a cooking appliance including the same according to an embodiment of the present disclosure will be described.

[0026] FIG. 1 is an overall perspective view of a cooking appliance according to one embodiment of the present disclosure, and FIG. 2 is an exploded perspective view of the cooking appliance shown in FIG. 1.

[0027] Referring to FIGS. 1 and 2, a cooking device (1000) according to an embodiment of the present disclosure may be a heating device that heats and cooks food using a heat source. For example, the cooking device (1000) may be an induction heating device (induction device, Induction) that utilizes the principle of induction heating. The cooking device (1000) transfers heat to a cooking container (CT) placed on the cooking device (1000) using the principle of induction heating.

[0028] The present disclosure does not specifically limit the heating principle of the cooking appliance (1000). For example, according to another embodiment of the present disclosure, the heating device may be an electric range (electric heater) or a radiant heater (hereinafter referred to as a highlight, Hi-Light) using radiant heat. The highlight heats an electric coil or a halogen lamp and transfers heat to a cooking vessel (CT) placed on the cooking appliance (1000) through direct radiant heat. That is, according to another embodiment of the present disclosure, the induction heating coils (121, 122, 123) shown in FIG. 2 may be replaced with an electric coil or a halogen lamp, and the driving chip, wires, etc. for driving them may be modified to correspond to the highlight configuration.

[0029] According to the present embodiment, a user interface (UI) may be provided in a portion of the area defined by the upper surface of the cooking appliance (1000). The user interface (UI) may include a power input unit (PW), a display unit (DP), and an operation unit (CR). The user can input power through the power input unit (PW) and control the cooking appliance (1000) through the operation unit (CR). Additionally, the user can check cooking information, including the temperature of the cooking container (CT), cooking elapsed time, and / or date / time, through the display unit (DP).

[0030] The cooking device (1000) includes a main body (100) and a plate for the cooking device (hereinafter, top plate) (200). The main body (100) can be detachably coupled to the top plate (200) positioned on the upper part of the main body.

[0031] The main body (100) includes a housing (110), a plurality of induction heating coils (121, 122, 123, 124, 125), a coil mounting plate (130), an interface board (140), and a structural circuit board (not shown).

[0032] The housing (110) forms the exterior of the cooking appliance (1000). The housing (110) can accommodate components of the main body (100) in the internal space defined by the housing (110). Additionally, the housing (110) can support a top plate (200) placed on the upper part of the housing (110). The housing (110) may have a box shape with an open top. In the present embodiment, the housing (110) has a rectangular shape in which the upper surface has a short side in the first direction (DR1) and a long side in the second direction (DR2) which is orthogonal to the first direction (DR1), but the specific shape of the housing (110) is not particularly limited in the present disclosure.

[0033] Induction heating coils (121, 122, 123, 124, 125) are housed inside the housing (110). The area where the induction heating coils (121, 122, 123, 124, 125) are placed defines a heating area. That is, a user can induction heat food inside a cooking utensil (CT) by placing the cooking utensil (CT) on an area on the upper surface of the cooking appliance (1000) corresponding to the area where the induction heating coils (121, 122, 123, 124, 125) are placed. The induction heating coils (121, 122, 123, 124, 125) have a shape wound approximately in a circular manner to form a magnetic field in a vertical direction when current is applied. The induction heating coils (121, 122, 123, 124, 125) are electrically connected to a driving circuit board (not shown) to receive a driving signal.

[0034] Induction heating coils (121, 122, 123, 124, 125) can be placed on a coil mounting plate (130). Guide holes for placing the induction heating coils (121, 122, 123, 124, 125) can be formed in the coil mounting plate (130).

[0035] As described above, in this embodiment, induction heating coils (121, 122, 123, 124, 125) are used as heat sources, but the present invention is not limited thereto. For example, according to another embodiment of the present disclosure, other induction heating sources using an induction heating method other than induction heating coils (121, 122, 123, 124, 125), electric coils using an electric resistance method, or halogen lamps, etc., may be used as heat sources.

[0036] An interface board (140) is placed inside a housing (110) to correspond to a user interface (IU) of a cooking device (1000). Specifically, the interface board (140) may include a display panel (141), a power input terminal (142a), and touch input terminals (142b, 142c). The display panel (141) is placed in an area corresponding to a display unit (DP). The power input terminal (142a) is placed in an area corresponding to a power input unit (PW), and the touch input terminals (142b, 142c) are placed in an area corresponding to an operation unit (CR). In this embodiment, the power input terminal (142a) and the touch input terminals (142b, 142c) may be touch electrodes that receive a touch signal.

[0037] A driving circuit board (not shown) is disposed inside the housing (110) and controls the driving of induction heating coils (121, 122, 123, 124, 125) and an interface board (140). In an embodiment of the present disclosure, the driving circuit board (not shown) may be disposed on the back surface of the coil mounting plate (130). However, the present disclosure is not particularly limited to the location of the driving circuit board (not shown).

[0038] The top plate (300) is positioned on the upper part of the main body (100). A display window (210) and a plurality of guide marks (PPa, PPb, PPc, PPd, PPe) may be formed on the upper surface of the top plate (200).

[0039] The display window (210) is provided so that the display panel (141) is exposed to the outside, and the area of ​​the top plate (200) where the display window (210) is formed may have light transmittance.

[0040] Multiple guide marks (PPa~PPe, 202a~202c) can be printed on the upper surface of a top plate through glass printing. For example, multiple guide marks (PPa~PPe, 202a~202c) can be formed by printing a pattern with glass ink on the upper surface and then heating it to a predetermined temperature so that the glass ink seeps into the top plate (200). In the present disclosure, the material used for glass printing can be used without special limitations as long as it is a component generally known as glass ink.

[0041] A plurality of guide marks (PPa~PPe, 202a~202c) may include heating area indicator marks (PPa~PPe) indicating a heating area, a power indicator mark (202a) indicating a power supply (PW), and controller marks (202b, 202c) indicating an operation unit (CR). In this embodiment, the top plate (200) may have the characteristic of being able to transmit an external touch signal to the power input terminal (142a) and the touch input terminals (142b, 142c).

[0042] Although not illustrated in the drawings, the cooking device (1000) according to an embodiment of the present disclosure may further include other components in addition to the main body (100) and the top plate (200). For example, the other components may be a ventilation device including a filter, a fan, etc.

[0043] In addition, a cooking device (1000) according to another embodiment of the present disclosure may be a single device in which a plurality of heating devices are combined. That is, a cooking device (1000) according to another embodiment of the present disclosure may further include another heating device that heats food in a manner different from that of the induction device at the bottom of the induction device. The other heating device may be an oven, an air fryer, a microwave oven, etc. According to the present embodiment, the user can select a different heating method to heat food depending on the use, thereby providing convenience to the user.

[0044] Figure 3 is a cross-sectional view of the line A-A' shown in Figure 2.

[0045] Referring to FIG. 3, the top plate (200) includes a glass layer (210), an uneven layer (220), an upper printing layer (230), and a lower printing layer (240). The glass layer (210), the uneven layer (220), the upper printing layer (230), and the lower printing layer (240) have a stacked form in a vertical direction.

[0046] The glass layer (210) may include a lithium aluminosilicate-based crystalline glass having Li2O, Al2O3, and SiO2 as a basic composition for heat resistance. Specifically, the glass layer (210) may include, in weight%, Li2O: 1 to 10 wt%, Al2O3: 14 to 25 wt%, and the remainder being SiO2 and impurities.

[0047] Li2O plays a role in improving the hardness of the glass layer (210). Therefore, if the content of Li2O is low, it may be difficult to ensure sufficient hardness of the glass layer (210). On the other hand, if the content of Li2O is excessive, manufacturing costs may increase. Therefore, it is preferable to contain 1 to 10 wt% of Li2O.

[0048] Al2O3 plays a role in improving the corrosion resistance and durability of the glass layer (210). Therefore, if the content of Al2O3 is low, the corrosion resistance and durability of the glass layer (210) may be inferior. On the other hand, if the content of Al2O3 is excessive, the manufacturing cost may increase. Therefore, it is preferable to contain 15 to 25 wt% of Al2O3.

[0049] SiO2 acts as a crystal nucleation agent for the glass layer (210). Therefore, if the SiO2 content is low, crystals within the glass layer (210) are not sufficiently formed, and the reflectivity may decrease. On the other hand, if the SiO2 content is excessive, the hardness and reconfiguration of the glass layer (210) may decrease. In addition, unintended impurities from raw materials or the surrounding environment may inevitably be incorporated during the normal manufacturing process, so they cannot be excluded. Since these impurities are known to any skilled technician in the normal manufacturing process, all such details are not specifically mentioned in this specification.

[0050] Generally, the color of the crystalline glass may vary depending on the content of the elements contained within the crystalline glass. Additionally, the crystalline glass may further include one or more elements selected from the group comprising V, Mg, P, Fe, Ti, Cr, and Zr, depending on the color to be achieved. According to an embodiment of the present disclosure, the glass layer (210) may be black, and the content of the V element may be increased to achieve the black color.

[0051] Additionally, the crystal phase of the glass layer (210) varies depending on the crystallization temperature, and the color of the glass layer (210) may vary depending on the crystal phase. That is, the crystal phase of the glass layer (210) may be at least one of beta-quartz (β-quarts), beta-spodumene (β-spodumene), or beta-eucryptite (β-eucryptite). In a preferred embodiment, the glass layer (210) may be based on a beta-quartz (β-quarts) crystal phase, but may have a form in which coloring elements such as titanium dioxide (TiO2) and vanadium pentoxide (V2O5) are added.

[0052] In Table 1, an exemplary table is provided showing the compositional materials and compositional ratios that constitute the glass layer (210) having a black color.

[0053] Ingredient content (wt%) SiO264.2Al2O321.7Fe2O30.14CaO0.09MgO0.28K2O0.23Na2O0.78TiO22.91Mn O0.02P2O50.85ZrO21.48Li2O4.64SrO0.01BaO1.41ZnO0.48HfO20.03V2O50.21Y2O30.01

[0054] In the present disclosure, the glass layer (210) may be radiant glass. Radiant glass can efficiently transfer or reflect radiant heat. Additionally, radiant glass has very high heat resistance and can be maintained stably without thermal shock or breakage even at high temperatures. For example, when the glass layer (210) is radiant glass, the glass layer (210) may have heat resistance with a heat deformation temperature of 650 to 1000°C. More preferably, the glass layer (210) may have heat resistance with a heat deformation temperature of 650 to 800°C. Additionally, radiant glass has a low coefficient of thermal expansion. For example, when the glass layer (210) is radiant glass, the coefficient of thermal expansion of the glass layer (210) is 3 × 10⁻⁶ -7 / ℃ to 5 × 10 -7 It can be / ℃.

[0055] The uneven layer (220) is formed on the upper surface of the glass layer (210). The uneven layer (220) refers to curved portions in a convex shape formed on the upper surface of the glass layer (210). The uneven layer (220) is formed to improve the scratch resistance and reduce visibility of the top plate (200), and when the surface roughness of the uneven layer (220) is adjusted to a predetermined range, scratch resistance and visibility can be reduced.

[0056] In this embodiment, the material of the uneven layer (220) includes the same material as the glass layer (210) and has an integral shape.

[0057] According to an embodiment of the present disclosure, the uneven layer (220) may have a surface roughness of 2 to 4 μm. In a more preferred embodiment, the surface roughness of the uneven layer (220) may be 2.6 to 3.8 μm.

[0058] If the surface roughness is 4 µm or more, the friction coefficient is high, so the surface may become excessively rough. In this case, contaminants may easily adhere to the surface of the top plate (200) and cleaning may become difficult. Contaminants such as dust, oil, and food residue may adhere well to a rough surface, and if said contaminants penetrate into the fine grooves on the surface of the top plate (200), they may be difficult to remove. In addition, a rough surface may have more places where scratches can occur, and contaminants may accumulate, making it more vulnerable to scratches. That is, if the surface roughness is 4 µm or more, the stain resistance and scratch resistance may be reduced.

[0059] On the other hand, if the surface roughness is 2 µm or less, the friction coefficient is low, so the surface may be excessively smooth. In this case, fingerprints or contaminants may easily remain on the surface of the top plate (220). Since a smooth surface has a low friction coefficient, it is not resistant to scratches, so oil or moisture from fingers may easily adhere to it, making it easy to leave fingerprints. In addition, small scratches on a smooth surface may be more easily visible. That is, if the surface roughness is 2 µm or less, visibility may increase and scratch resistance may decrease.

[0060] According to one embodiment of the present disclosure, the top plate (220) may have a vertical force of 15 to 20 N at which scratches occur.

[0061] Figure 4 is an enlarged cross-sectional view of region B shown in Figure 3.

[0062] Referring to FIG. 4 together with FIG. 3, the uneven layer (220) of the top plate (200) according to an embodiment of the present disclosure includes a chemical strengthening region (221). The chemical strengthening region (221) is formed in the upper portion of the uneven layer (220) in cross-section. Specifically, the chemical strengthening region (221) is defined as an area extending from the upper surface of the uneven layer (220) to a predetermined depth in the downward direction.

[0063] The chemical strengthening region (221) is formed by a chemical strengthening process. The chemical strengthening process is a process that strengthens the surface of the top plate (200) (specifically, the uneven layer (220)) using a strengthening salt, and increases the strength and durability of the top plate (200) through ion exchange. The chemical strengthening process is performed by immersing the top plate (200) in a strengthening salt solution.

[0064] In this embodiment, the reinforcing salt may include at least one of KNO3 or NaNO3, and lithium ions (Li) in a relatively small upper plate (200) + ) and the cation of the relatively large reinforcing salt (K + and / or Na + Ion exchange can occur between ). Therefore, potassium (K + The fraction of ) is lithium (Li + It can be higher than the fraction of ).

[0065] According to the present embodiment, during ion exchange, relatively large potassium ions (K + ) small size lithium-ion (Li +While replacing ), inwardly directed compressive stress may be formed on the surface of the uneven layer (220) due to the size difference between the ions. The magnitude of the formed compressive stress has a value greater than the internal stress, and when an impact occurs, the phenomenon of cracks forming on the surface of the uneven layer (220) due to the compressive stress is prevented, thereby protecting the surface of the uneven layer (220). In this embodiment, the compressive stress of the top plate (200) may be 480 MPa or more.

[0066] The chemical strengthening depth is defined as the depth at which the surface of the uneven layer (220) is saturated with cations (K+) by ion exchange, and in this embodiment, the chemical strengthening depth may be 10 µm or more. If the chemical strengthening depth is less than 10 µm, the effects of improving surface hardness and drop strength cannot be achieved simultaneously.

[0067] The top plate (200) according to an embodiment of the present disclosure may have a bending strength of 120 MPa or more, and the drop rate of a 535 g steel ball when dropped from a height of 1000 mm may be 10% or less. In addition, the Vickers hardness of the top plate (200) may be 950 to 1,200 Hv.

[0068] FIG. 4 shows the surface of the uneven layer (220) of the top plate (200) chemically strengthened by a reinforcing salt (KNO3), and shows the state in which ion exchange occurs between the surface of the uneven layer (220) and the reinforcing salt.

[0069] The upper printing layer (230) is placed on top of the uneven layer (220). The upper printing layer (230) may be the aforementioned guide marks (PPa~PPe, 202a~202c).

[0070] The lower printing layer (240) is placed below the glass layer (210).

[0071] In the present disclosure, the material included in the lower printing layer (240) is not particularly limited, but as an example, the lower printing layer (240) may be based on a polyester-based polymer material and may include titanium oxide (TiO2), silicon oxide (SiO2), glass beads, silicon (Si), chromium (Cr), and magnesium (Mg), etc., depending on the color to be realized. In addition, the lower printing layer (240) may have a large amount of inorganic materials and metal pigments added to ensure heat resistance of the ink. In addition, cyclohexane, trimethylbenzene, and methyl methacrylate, etc., may be used as solvents and curing agents.

[0072] In this embodiment, a light-blocking area (AR1) that blocks light transmission and a light-transmitting area (AR2) that transmits light may be defined on the top plate (200) in a flat plane. The lower printing layer (240) may be positioned to correspond only to the light-blocking area (AR1). That is, the lower printing layer (240) is not positioned in the light-transmitting area (AR2).

[0073] The light-blocking area (AR1) can block the transmission of light so that the color of the top plate (200) is realized by the lower printing layer (240), and prevents the components of the cooking device (1000) placed below the top plate (200) from being visible from the outside. The light-transmitting area (AR2) can transmit light to expose specific components of the cooking device (1000) placed below the top plate (200) to the outside. For example, the light-transmitting area (AR1) overlaps with the display unit (DP, FIG. 1) on a plane so that the display panel (141, FIG. 2) can be exposed from the outside.

[0074] In this embodiment, the top plate (200) in the light-blocking area (AR1), where light is blocked by the lower printing layer (240), may have a color tone of L*: 20.0 to 21.5, a*: 0.1 to 0.3, and b*: 0.1 to 0.4. On the other hand, the top plate (200) in the light-transmitting area (AR2), where light is transmitted because the lower printing layer (240) is not placed, may have a color tone close to brown, for example, L*: 22 to 24.0, a*: 0.3 to 0.9, and b*: 0.4 to 1.0.

[0075] Although not illustrated in the drawings, a top plate (200) according to another embodiment of the present disclosure may further include a coating layer (not illustrated). The coating layer may be disposed on the uppermost part of the top plate (200). The coating layer may be applied for purposes such as anti-fingerprint function, ease of cleaning, anti-fouling properties, texture expression, and enhanced scratch resistance, and the material and process method of the coating layer may vary depending on the intended application. In the present disclosure, the type of coating layer is not specifically limited.

[0076] Generally, when a cooking vessel (CT) is placed on top of a cooking appliance and cooking is performed, continuous friction occurs on the upper surface of the top plate. Therefore, it is required to improve the hardness, strength, and scratch resistance of the top plate (200) to reduce impact strength and scratches. According to an embodiment of the present disclosure, the Vickers hardness of the top plate (200) is 950 to 1,200 Hv, the bending strength is 120 MPa or more, and the drop ball breakage rate is 10% or less when a 535g steel ball is dropped from a height of 1,000 mm. In addition, the vertical force causing scratches on the top plate (200) is 15 to 20 N. Therefore, according to an embodiment of the present disclosure, a cooking appliance (1000) with improved hardness, strength, and scratch resistance can be provided.

[0077] In addition, the cooking device (1000) according to the present disclosure may have improved heat resistance by using radiant glass.

[0078] Next, a method for manufacturing a plate (1000) for a cooking appliance according to one embodiment of the present disclosure will be described.

[0079] FIG. 5 is a flowchart of a method for manufacturing a cooking appliance according to one embodiment of the present disclosure.

[0080] Referring to FIG. 5, a method for manufacturing a plate (200) for a cooking appliance according to one embodiment of the present disclosure comprises the steps of: manufacturing a ceramic glass precursor (S1); heating the ceramic glass precursor to form a crystal (S2); cooling the ceramic glass with the crystal to form a substrate having a glass layer (210) (S3); blasting the glass layer (210) (S4); first etching the blasted glass layer (210) to form an uneven layer (220) (S5); polishing the top plate (200) having the uneven layer (220) formed thereon (S6); second etching the top plate (200) after the polishing process is completed (S6); and chemically strengthening (S7).

[0081] First, in the step (S1) of manufacturing a ceramic glass precursor, ceramic glass powder is prepared, then melted at 1400 to 1600°C, and then cooled at a cooling rate of 40°C / min or less at room temperature to manufacture a ceramic glass precursor.

[0082] Subsequently, a crystal generation step (S2) is performed to generate crystals within the glass layer (210). The crystal generation step (S2) may include a first heating step of maintaining at 600 to 800°C for 10 to 20 minutes and a second heating step of maintaining at 800 to 1000°C for 20 to 30 minutes. According to one embodiment of the present disclosure, nuclei for crystallization within the ceramic glass are generated through the first heating step, and crystallization can proceed based on the generated nuclei during the second heating step. If the temperature of the crystal generation step is too low or the holding time is too short, crystals are not sufficiently generated, which may result in reduced color clarity and reflectivity. However, if the temperature of the crystal generation step is too high or the holding time is too long, productivity may decrease. Therefore, it is desirable to set the crystal generation step temperature and holding time at an appropriate level.

[0083] In the cooling step (S3), the glass ceramic is cooled to room temperature at a cooling rate of 20°C / min or more to form a glass layer (210). The glass layer (210) has a substrate shape. According to the present embodiment, since the cooling step execution time is short, the color clarity of the glass layer (210) can be improved.

[0084] According to another embodiment of the present disclosure, a step of masking the glass layer (210) may be additionally performed after the cooling step (S3). The masking step corresponds to a process that selectively prevents a subsequent process from being performed on a portion of the glass layer (210). At least one subsequent process may not be performed on the portion that has been masked. In this case, the optical properties, physical / mechanical properties of the portion may differ from those of the portion that has not been masked. For example, the portion may be at least the light-transmitting area (AR2) of the top plate (200). In this embodiment, the portion of the glass layer (210) corresponding to the light-transmitting area (AR2) may be masked at a Lami speed of 2 to 4 m / min, a Lami tension of 10 to 20%, and an atmospheric pressure of 0.6 to 0.8 MPa.

[0085] Afterwards, a step (S4) of blasting the glass layer (210) and a step (S5) of first etching the glass layer (210) are performed.

[0086] In this embodiment, in the blasting step (S4), the blasting process can be performed using diamond or diamond + boron carbide.

[0087] In the first etching step (S5), the first etching may be chemical etching. The first etching may be performed by immersing the glass layer (210) in hydrofluoric acid. More specifically, the first etching may be performed by spraying hydrofluoric acid onto the glass layer (210) at room temperature and then immersing the glass layer (210) in hydrofluoric acid for 60 to 180 minutes.

[0088] In this embodiment, the case where only the upper surface of the glass layer (210) is etched is described. In this case, the back surface (lower surface) of the glass layer (210) may be masked. However, in other embodiments of the present disclosure, the first etching may be performed simultaneously on the upper surface and the lower surface of the glass layer (210).

[0089] A top plate (200) having an uneven layer (220) formed on the upper surface of a glass layer (210) can be manufactured through a blasting process and a first etching process. In the present disclosure, the methods for the blasting process and the first etching process are not particularly limited.

[0090] The uneven layer (220) after the first etching is completed undergoes a polishing step (S6). Through the polishing step (S6), the surface roughness and glossiness of the top plate (200) can be controlled.

[0091] The polishing step (S6) can be performed for 5 to 10 minutes. After applying an abrasive to a polishing pad (Softbuff), the molded top plate (200) can be polished, thereby making the surface of the top plate (200) smooth and maximizing cleanability.

[0092] Generally, as the duration of the crystal formation step increases and the duration of the cooling step decreases, the color clarity of the glass layer (210) improves, but the surface of the glass layer (210) may have many irregularities, which may reduce cleanability. Therefore, the duration of the cooling step is generally not shortened. However, in the method for manufacturing the glass layer (210) according to one embodiment of the present disclosure, the color clarity can be improved by performing the cooling step at a rapid cooling rate of 20°C / min or more, while simultaneously improving cleanability through the polishing step.

[0093] After the polishing step (S6) is completed, a second etching (Dual Nano Etching) is performed on the top plate (200) (S7). The second etching may be a chemical etching as a pretreatment for the chemical strengthening process (S8). The second etching may be performed by immersing the top plate (200) in hydrofluoric acid. In this embodiment, the time for performing the second etching may be shorter than the time for performing the first etching. For example, the time for performing the second etching may be immersed in hydrofluoric acid for 1 minute or less. Through the second etching process, the uneven layer (220) is not substantially etched, but impurities on the surface of the uneven layer (220) are removed, and the uniformity of the unevenness of the uneven layer (220) is made uniform. Therefore, by performing a second etching process, the surface of the top plate (200) is pretreated, thereby enabling the chemical strengthening process to be performed effectively.

[0094] If the second etching execution time is 1 minute or more, the uneven layer (220) actually begins to be etched. Therefore, the second etching execution time is preferably 1 minute or less.

[0095] Since the second etching process is a wet etching process, the second etching process can be performed simultaneously on the upper surface and lower surface (front and back) of the top plate (200). If the first etching process is not performed on the lower surface of the top plate (200), the surface roughness of the upper surface of the top plate (200) may differ from the surface roughness of the lower surface. That is, according to the present disclosure, whether the first / second etching process is performed on the lower surface of the top plate (200) can be determined according to the required optical / physical function.

[0096] The top plate (200) after the second etching process (S7) is completed undergoes chemical strengthening treatment (S8).

[0097] In the chemical strengthening step (S8), the surface of the top plate (200) is treated with a strengthening salt containing at least one of NaNO3 or KNO3 at a concentration of 90 to 100 wt% at a temperature of 350 to 450°C for 1 hour or more and 12 hours or less. In a preferred embodiment, for a black top plate (200), the strengthening salt treatment time may be 8 hours or more and 12 hours or less. If the chemical strengthening time is less than 8 hours, chemical strengthening of sufficient depth is not performed, and the drop ball breakage rate exceeds 10%, so it is preferable to perform it for 8 hours or more.

[0098] In another embodiment of the present invention, the strengthening salt treatment may be repeated one or more times.

[0099] In this embodiment, the glossiness of the top plate (200) after completing all the aforementioned processes may be 5 to 25. At this time, the glossiness is the amount of light reflected when light is incident on the top plate (200) at an angle of 60 degrees, i.e., the surface reflectance value. The glossiness may be expressed as a value between 0 and 100, and the higher the value, the smoother and shinier the surface is and the better it reflects light, and the lower the value, the rougher or closer to matte the surface is and the less it reflects light.

[0100] According to another embodiment of the present disclosure, the step (S9) of forming printed layers (230, 240) on the upper and lower parts of the upper plate (200) after the chemical strengthening process (S8) is completed may be further included (S9).

[0101] Among the steps (S9) of forming a printing layer, the step of forming an upper printing layer (230) may include the step of heating the upper plate (200) on which the upper printing layer (230) is printed at a temperature of 500 to 800°C or lower for 5 to 15 minutes. Additionally, the step of forming a lower printing layer (240) may include the step of heating the upper plate (200) on which the lower printing layer (240) is printed at a temperature of 200 to 300°C for 10 to 20 minutes.

[0102] In this embodiment, the lower printing layer (240) is not formed in the area overlapping with the light-transmitting area (AR2) on the back surface of the top plate (200).

[0103] Additionally, according to another embodiment of the present disclosure, the step (S10) of forming a coating layer (not shown) on the uppermost part of the top plate (200) on which the printed layer (230, 240) is formed may be further included.

[0104] The coating layer can be formed by applying a coating solution to the entire upper surface of the top plate (200) and then drying it at 600 to 800°C for 5 to 15 minutes.

[0105] If the drying temperature is low or the processing time is short, the coating layer may not be formed uniformly, and if the drying temperature is too high or the processing time is too long, cracks may occur on the surface of the coating layer.

[0106] The present disclosure does not specifically limit the method of manufacturing the coating layer.

[0107] FIG. 6 is a table showing the scratch visibility and the vertical force at the time of scratch occurrence according to the surface roughness and glossiness of the embodiments and comparative examples of the present disclosure.

[0108] In FIG. 6, the embodiment is a top plate (200) having a surface roughness of 3.5 μm and a glossiness of 5.0. Comparative Example 1 and Comparative Example 2 are top plates having a surface roughness of 0.05 μm and 1.5 μm, respectively, which is less than the lower limit of the surface roughness range according to the embodiment of the present disclosure, and Comparative Example 3 is a top plate having a surface roughness of 6.5 μm, which is greater than the upper limit of the surface roughness range according to the embodiment of the present disclosure.

[0109] Referring to Fig. 6, in order to confirm the effect of improving scratch resistance according to surface roughness, as a first experiment, scratch tests were performed on top plates using a blue scouring pad with a load of 1 kfg from 1 to 50 times.

[0110] As a result, in Comparative Example 1, which has low surface roughness, it was confirmed that a scratch was visible on the top plate with only one scratch.

[0111] Even in Comparative Example 2, which has a surface roughness higher than Comparative Example 1 but a surface roughness value smaller than that required in the present disclosure, a single scratch was not significantly visible to the naked eye, but from 10 times or more, a scratch on the top plate was clearly visible to the naked eye.

[0112] According to an embodiment of the present disclosure, in the case of a top plate (200) having a surface roughness of 3.5 μm, even after performing 50 scratches, no scratches were visible to the naked eye on the top plate (200).

[0113] In the case of Comparative Example 3, as a result of performing 50 scratch tests, no scratches were visible, but scratch residue remained, and contaminants were relatively visible compared to the top plate of the Example. Whether contaminants are visible can be determined by whether the color difference (ΔE) before and after the scratch test is 1.5 or less. In the case of Comparative Example 3, the color difference (ΔE) before and after the scratch test was measured to be 1.5 or more, so it was determined that contaminants were visible.

[0114] The top plate of Comparative Example 3 has a surface roughness exceeding 4 µm and a glossiness of 1.5, which is less than the lower limit of the glossiness range required in the present disclosure, which is 5. In this case, because the surface roughness is high and the glossiness is low, the surface is very rough, so contaminants stick to it easily and may be difficult to remove.

[0115] In order to confirm the effect of improving scratch resistance according to surface roughness, the vertical force at the time of scratch occurrence was measured and recorded in the second experiment. The variable load scratch test was measured using a Fischersope-HM2000 instrument in accordance with ASTM c-1624-05 Scratch Testing. At this time, the vertical force applied to the specimen was increased steadily from 0.5 N to 20 N, and the scratch behavior was observed through an optical or electron microscope while moving the specimen at a speed of 240 mm / s.

[0116] As a result of the measurement, the vertical force of top plates satisfying a surface roughness value of 2 or higher was measured to be 17.5N and 18.3N, confirming that they have better scratch resistance than top plates with a surface roughness of less than 2.

[0117] Next, to test the drop limit of the top plate, 535g steel balls were vertically dropped from different heights onto the center of the top plate's burner a total of 8 times as a set to check for damage. Table 2 shows the results of the drop limit test, where damage was marked as NG and no damage was marked as OK, and the limit drop height was indicated.

[0118] 514mm 600mm 700mm 800mm 900mm 1000mm Result Example 1 OK OK OK OK OK OK 1000mm Example 2 OK OK OK OK OK OK 1000mm Example 3 OK OK OK OK OK OK 1000mm Comparative Example 4 OK OK NG --- 600mm Comparative Example 5 OK OK OK NG --- 700mm Comparative Example 6 OK OK NG --- 600mm

[0119] The top plates of Examples 1 to 3 were manufactured according to the manufacturing method of the present disclosure, while the top plates of Comparative Examples 1 to 3 were manufactured according to a conventional manufacturing method and were not subjected to an etching process or chemical strengthening treatment. Referring to Table 2, it was confirmed that the top plates manufactured according to the manufacturing method of the present disclosure (Examples 1 to 3) did not break at 1000 mm or less, and the limit drop height was 1000 mm or more. However, in the case of the top plates manufactured according to a conventional manufacturing method (Comparative Examples 4 to 6), the maximum drop height was 700 mm or less, and it was confirmed that their strength was inferior compared to the examples of the present disclosure. Next, Vickers hardness and flexural strength were measured according to the chemical strengthening depth (time) for the top plates manufactured according to the conditions of the manufacturing method of the present disclosure, and the results are shown in Table 3.

[0120] Chemical Strengthening Time Vickers Hardness (Hv) Flexural Strength (MPa) - 750 66.24 hours 800 80.26 hours 113 39 5.18 hours 117 310 2.4 10 hours 113 710 3.1 12 hours 112 098

[0121] Referring to Table 3, it was confirmed that in the case of a top plate according to the present disclosure, a top plate that has undergone chemical strengthening treatment for 8 hours or more has a Vickers hardness of 1120 Hv or higher and a bending strength of 98 MPa or higher. A plate (200) for a cooking appliance according to an embodiment of the present disclosure includes a glass layer (210) having a black color and an uneven layer (220) disposed on the glass layer (210), and the surface roughness (Ra) of the uneven layer (220) is 2 to 4 μm. The uneven layer (220) includes a chemical strengthening region (210) formed in the upper part of the cross-section, and the fraction of potassium in the chemical strengthening region (210) is higher than the fractions of lithium and sodium.

[0122] The depth of the chemical strengthening region (210) is 10 µm or more.

[0123] The above glass layer (210) has heat resistance with a heat deformation temperature of 650°C or higher.

[0124] The plate (200) for the cooking device has a glossiness of 5 to 25 based on a light incidence angle of 60 degrees.

[0125] The above glass layer (210) comprises a lithium aluminosilicate crystalline glass having Li2O, Al2O3 and SiO2 as its basic composition.

[0126] The above-mentioned plate (200) for the cooking device has a vertical force of 15 to 20 N that causes scratches.

[0127] The above-mentioned plate (200) for a cooking device has a bending strength of 98 MPa or more and a Vickers hardness of 1120 Hv or more.

[0128] The above-mentioned plate (200) for cooking equipment has a drop rate of 10% or less when a 535g steel ball is dropped from a height of 1000mm.

[0129] The above-described plate (200) for a cooking device has a light-transmitting area (AR2) and a light-blocking area (AR1) defined on a flat surface, and further includes a lower printing layer (230) disposed below the glass layer (210) to block light transmitted from the glass layer (210), and the lower printing layer (230) is disposed to overlap with the light-blocking area (AR1) on the flat surface and does not overlap with the light-transmitting area (AR2).

[0130] The above-mentioned plate (200) for the cooking device has a color value of L*: 20.0 ~ 21.5, a*: 0.1 ~ 0.3, and b*: 0.1 ~ 0.4 in the above-mentioned light-blocking area (AR1).

[0131] A method for manufacturing a plate for a cooking appliance according to an embodiment of the present disclosure comprises the steps of: manufacturing a ceramic glass precursor (S1); heating the ceramic glass precursor to form a crystal (S2); cooling the ceramic glass from which the crystal has been formed to form a glass layer (210) in the form of a substrate (S3); blasting at least one surface of the substrate (S4); first etching at least one surface of the blasted substrate to form an uneven layer (220) on the surface of the substrate (S5); polishing the surface of the substrate (S6); second etching at least one surface of the substrate from which the polishing is completed to remove impurities from the substrate (S7); and chemically strengthening at least one surface of the substrate from which the second etching is completed (S8), wherein the surface roughness of the surface of the substrate from which the chemical strengthening is completed is 2 to 4 μm.

[0132] In the above second etching step, the time for performing the second etching is shorter than the time for performing the first etching.

[0133] The chemical strengthening step includes the step of treating at least one surface of the substrate with a strengthening salt at a temperature of 350 to 450°C for a predetermined time.

[0134] The above-mentioned reinforcing salt contains at least one of KNO3 or NaNO3.

[0135] The above predetermined time is 8 hours or more and 12 hours or less.

[0136] After the chemical strengthening step (S8), the method further includes a step (S9) of forming a lower printing layer (240) on at least a portion of the lower surface of the substrate, wherein the lower printing layer (240) blocks light transmitted from the substrate.

[0137] A cooking device (1000) according to an embodiment of the present disclosure comprises a cooking device plate (200) having a black color on which a cooking container (CT) is placed, and a main body (100) disposed below the cooking device plate and including a plurality of heating coils, wherein the cooking device plate (200) comprises a glass layer (210) having heat resistance with a heat deformation temperature of 650°C or higher, and an uneven layer (220) disposed on the glass layer (210) and having a surface roughness (Ra) of 2 to 4 μm.

[0138] The vertical force causing scratches on the above-mentioned cooking plate (200) is 15 to 20 N, and the drop rate of a 535 g steel ball is 10% or less when dropped from a height of 1000 mm onto the center of the above-mentioned cooking plate.

[0139] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs from the description below.

[0140] Specific embodiments have been illustrated and described above. However, the invention is not limited to the embodiments described above, and a person skilled in the art may make various modifications without departing from the essence of the technical concept of the invention as described in the following claims.

Claims

A glass layer having a black color; and It includes an uneven surface layer disposed on the glass layer above, and A plate for a cooking appliance having a surface roughness (Ra) of the above-mentioned uneven layer of 2 to 4 μm. In Article 1, The above-mentioned uneven layer includes a chemically strengthened region formed in the upper portion of the cross-section, and A plate for cooking appliances in which the fraction of potassium in the above chemical strengthening region is higher than the fractions of lithium and sodium. In Article 2, A plate for a cooking appliance in which the depth of the chemically strengthened region is 10 µm or more. In Article 1, The above glass layer is a plate for a cooking appliance having heat resistance with a heat deformation temperature of 650°C or higher. In Article 1, A plate for cooking appliances having a glossiness of 5 to 25 based on a light incidence angle of 60 degrees. In Article 1, The above glass layer is a plate for a cooking appliance comprising lithium aluminosilicate-based crystalline glass having Li2O, Al2O3, and SiO2 as a basic composition. In Article 1, A plate for a cooking appliance where a vertical force causing scratches is 15 to 20 N. In Article 1, A plate for cooking appliances having a flexural strength of 98 MPa or higher and a Vickers hardness of 1120 Hv or higher. In Article 1, A plate for cooking appliances having a drop ball breakage rate of 10% or less when a 535g steel ball is dropped from a height of 1000mm. Step of manufacturing a ceramic glass precursor; A step of heating the ceramic glass precursor to form crystals; A step of cooling the ceramic glass on which the above-mentioned crystal has been formed to form a glass layer in the form of a substrate; A step of blasting at least one surface of the above substrate; A step of forming an uneven surface layer on the substrate surface by first etching at least one surface of the blasted substrate; A step of polishing one surface of the above substrate; A step of removing impurities from the substrate by secondarily etching at least one surface of the polished substrate; and The method includes the step of chemically strengthening at least one surface of the substrate on which the second etching is completed, and A method for manufacturing a plate for a cooking appliance, wherein the surface roughness of one side of the above-mentioned chemically strengthened substrate is 2 to 4 μm. In Article 10, A method for manufacturing a plate for a cooking appliance in which, in the step of the second etching above, the time for performing the second etching is shorter than the time for performing the first etching. In Article 10, A method for manufacturing a plate for a cooking appliance, wherein the chemical strengthening step comprises the step of treating at least one surface of the substrate with a strengthening salt at a temperature of 350 to 450°C for a predetermined time. In Article 12, A method for manufacturing a plate for a cooking appliance in which the above-mentioned reinforcing salt comprises at least one of KNO3 or NaNO3. In Article 12, A method for manufacturing a plate for a cooking appliance, wherein the above-mentioned predetermined time is 8 hours or more and 12 hours or less. In Article 10, After the chemical strengthening step, the method further includes the step of forming a lower printed layer on at least a portion of the lower surface of the substrate, and A method for manufacturing a plate for a cooking appliance in which the lower printing layer blocks light transmitted from the substrate.

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