Cooker top plate

Abstract

Provided is a cooker top plate capable of effectively improving scratch resistance.　A cooker top plate 1 includes: a glass substrate 2 having a cooking surface 2a on which a cooking implement is placed, and a rear surface 2b on the side opposite from the cooking surface 2a; and a heat-resistant resin layer 3 disposed on the rear surface 2b of the glass substrate 2. The heat-resistant resin layer 3 includes silicone resin and a needle-like crystal pigment.

Description

[Technical Field]

[0001] The present invention relates to a top plate for a cooker. [Background technology]

[0002] Heat-resistant glass substrates made of crystallized glass, borosilicate glass, or the like, which have a low thermal expansion coefficient, are used for top plates of cookers such as induction cookers, radiant heater cookers, and gas cookers. The glass substrates for such cooker top plates have a cooking surface and a back surface located inside the cooker.

[0003] A heat-resistant resin layer containing a silicone resin may be provided on the back surface of the glass substrate in the top plate for a cooking appliance for the purposes of concealing the internal structure of the cooking appliance and increasing heat resistance.

[0004] For example, Patent Document 1 below discloses a top plate for a cooker, which includes a transparent crystallized glass plate and a decorative layer formed on the surface of the transparent crystallized glass plate facing an electromagnetic heating device and made of a mixture of silicone resin and inorganic pigment. Patent Document 1 also describes that the molar ratio of organic groups to Si (organic groups / Si) in the silicone resin is 0.1 to 1.5.

[0005] Furthermore, Patent Document 2 below discloses a top plate for a cooker having a glass plate and a heat-resistant resin layer provided in contact with the rear surface of the glass plate. It is described that the heat-resistant resin layer contains a heat-resistant resin having heat resistance and a flake-shaped inorganic filler such as plates or scales having a Mohs hardness of 3 or more. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-298266 [Patent Document 2] Japanese Patent Application Publication No. 2020-094799 Summary of the Invention [Problem to be solved by the invention]

[0007] However, a top plate for a cooking appliance may be scratched during the transport process when it is installed in the cooking appliance, or when it comes into contact with surrounding components, etc. Therefore, the heat-resistant resin layer provided on the top plate for a cooking appliance is required to have improved scratch resistance.

[0008] However, when the crosslinking density is increased by increasing the amount of functional groups in the resin, as in Patent Document 1, cracks and breakages may occur in the heat-resistant resin layer. Also, when a scaly pigment or the like is used as the pigment, as in Patent Document 2, adhesion may decrease depending on storage conditions, and surface peeling may occur in the heat-resistant resin layer. Therefore, there is a problem that it is still difficult to sufficiently improve the scratch resistance of the top plate for the cooker.

[0009] An object of the present invention is to provide a top plate for a cooker that can effectively improve scratch resistance. [Means for solving the problem]

[0010] The top plate for a cooker according to the present invention comprises a glass substrate having a cooking surface on which a cooking utensil is placed and a back surface opposite the cooking surface, and a heat-resistant resin layer disposed on the back surface of the glass substrate, the heat-resistant resin layer containing a silicone resin and a needle-shaped crystal pigment.

[0011] In the present invention, the needle crystal pigment is preferably at least one selected from the group consisting of potassium titanate, calcium silicate, and titanium oxide, and more preferably potassium titanate.

[0012] In the present invention, it is preferable that the heat-resistant resin layer further contains a scaly pigment, and it is more preferable that the scaly pigment is mica or aluminum.

[0013] In the present invention, the pigment mass concentration of the needle crystal pigment in the heat-resistant resin layer is preferably 3% or more and 50% or less.

[0014] In the present invention, it is preferable that the heat-resistant resin layer has a first layer containing a first color pigment and a second layer provided on the first layer and containing a second color pigment different from the first color pigment, and at least one of the first layer and the second layer contains the needle crystal pigment. It is more preferable that the second layer contains the needle crystal pigment. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a top plate for a cooker that can effectively improve scratch resistance. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view showing a top plate for a cooker according to a first embodiment of the present invention. [Figure 2] FIG. 5 is a schematic cross-sectional view showing a top plate for a cooker according to a second embodiment of the present invention. [Figure 3] FIG. 10 is a schematic cross-sectional view showing a top plate for a cooker according to a third embodiment of the present invention. [Figure 4] 1 is a scanning electron microscope photograph of a cross section of a heat-resistant resin layer obtained in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in each drawing, components having substantially the same functions may be referred to by the same reference numerals.

[0018] [First embodiment] FIG. 1 is a schematic cross-sectional view showing a top plate for a cooker according to a first embodiment of the present invention. As shown in FIG. 1, the top plate for a cooker 1 (hereinafter, the "top plate for a cooker" will be simply referred to as the "top plate") includes a glass substrate 2. The glass substrate 2 has a cooking surface 2a and a back surface 2b that face each other. The cooking surface 2a is the surface on which a cooking utensil such as a pot or frying pan is placed. The back surface 2b is the surface that faces a light source or a heating device inside the cooker. Therefore, the cooking surface 2a and the back surface 2b are in a front-back relationship.

[0019] A heat-resistant resin layer 3 is provided on the rear surface 2b of the glass substrate 2. In this embodiment, the heat-resistant resin layer 3 has a first layer 4 and a second layer 5. More specifically, the first layer 4 is laminated on the rear surface 2b of the glass substrate 2, and the second layer 5 is laminated thereon. In this embodiment, both the first layer 4 and the second layer 5 contain a silicone resin and a needle crystal pigment.

[0020] The top plate 1 for a cooker of this embodiment has the above-mentioned configuration, and therefore can effectively improve scratch resistance.

[0021] Conventionally, top plates have been prone to scratches during the transport process when installed in a cooker, or when they come into contact with surrounding components, etc. Therefore, there has been a demand for improved scratch resistance in the heat-resistant resin layer provided on the top plate.

[0022] Therefore, one possible method for improving scratch resistance is to increase the crosslink density by increasing the amount of functional groups in the resin, but this method can cause cracks and breakage in the heat-resistant resin layer.The reason for this is thought to be that if the amount of functional groups is increased excessively, the heat-resistant resin layer becomes more susceptible to cracks and breakage due to volumetric shrinkage associated with the reaction.

[0023] Furthermore, when an attempt is made to improve scratch resistance by increasing the pigment ratio in the heat-resistant resin layer, the amount of resin in the heat-resistant resin layer becomes relatively small, which can result in a decrease in adhesion strength or embrittlement.

[0024] Furthermore, when attempting to improve scratch resistance by using a scaly pigment as the pigment, adhesion can decrease depending on storage conditions, and surface peeling can occur in the heat-resistant resin layer. This tendency is particularly pronounced when the top plate is exposed to water or boiling water. The reason for this is thought to be that the scaly pigment is oriented in a direction parallel to the heat-resistant resin layer, which increases resistance to shrinkage forces parallel to the heat-resistant resin layer, but tends to decrease cohesive strength against shrinkage forces perpendicular to the heat-resistant resin layer.

[0025] In response to this, the inventors focused on the pigment contained in the heat-resistant resin layer of the top plate for the cooker and discovered that by using a needle-shaped crystal pigment as the pigment contained in the heat-resistant resin layer, the scratch resistance of the top plate can be effectively improved.

[0026] Although the reason for this is unclear, it is thought that when needle-shaped crystal pigments are used, the pigments become entangled with each other and function as aggregates, suppressing the volumetric shrinkage of the silicone resin, thereby suppressing the occurrence of breakage or cracks in the heat-resistant resin layer due to the volumetric shrinkage of the silicone resin, and increasing the fracture strength.Furthermore, unlike pigments such as scale-like pigments, they do not have orientation in a specific direction, so surface peeling is less likely to occur.

[0027] Each layer constituting the top plate 1 will be described in detail below.

[0028] (glass substrate) The glass substrate 2 transmits at least a portion of light in the wavelength range of 450 nm to 700 nm. The glass substrate 2 may be colored and transparent, but is preferably colorless and transparent from the viewpoint of further enhancing the aesthetic appearance of the top plate 1. In this specification, "transparent" means that the light transmittance in the visible wavelength range of 450 nm to 700 nm is 70% or more.

[0029] The top plate 1 is repeatedly heated and cooled. Therefore, it is preferable that the glass substrate 2 has high heat resistance and a low coefficient of thermal expansion. Specifically, the softening temperature of the glass substrate 2 is preferably 700°C or higher, and more preferably 750°C or higher. In addition, the average linear thermal expansion coefficient of the glass substrate 2 in the range of 30°C to 750°C is -10×10 -7 / ℃~+60×10 -7 / °C, and is preferably within the range of -10 × 10 -7 / ℃~+50×10 -7 / °C, and more preferably within the range of -10 × 10 -7 / ℃~+40×10 -7 / °C. Therefore, the glass substrate 2 is preferably made of glass with a high glass transition temperature and low expansion, or low-expansion crystallized glass. A specific example of low-expansion crystallized glass is "N-0" manufactured by Nippon Electric Glass Co., Ltd. Note that borosilicate glass or the like may also be used for the glass substrate 2.

[0030] There is no particular limitation on the thickness of the glass substrate 2. The thickness of the glass substrate 2 can be set appropriately depending on the light transmittance, etc. The thickness of the glass substrate 2 can be, for example, about 2 mm to 6 mm.

[0031] (Heat-resistant resin layer) When the heat-resistant resin layer 3 contains a pigment, it preferably has a first layer 4 and a second layer 5 disposed on the first layer 4. By forming the heat-resistant resin layer 3 into two layers, the pigment content of the heat-resistant resin layer 3 can be maintained or increased even if the pigment ratio of each of the first layer 4 and the second layer 5 is reduced to prevent a decrease in the adhesive strength between the glass substrate 2 and the heat-resistant resin layer 3. This further enhances the concealment of the internal structure of the cookware. Furthermore, the first layer 4 and the second layer 5 are preferably colored differently. For example, the first layer 4 can be a white coating film, and the second layer 5 can be a gray coating film. However, the colors of the first layer 4 and the second layer 5 are not particularly limited and can be determined appropriately taking into consideration the design and the concealment of the internal structure of the cookware. The heat-resistant resin layer 3 may also have three or more layers.

[0032] The first layer 4 and the second layer 5 each contain a silicone resin and a needle-shaped crystal pigment. In the present invention, it is sufficient that at least one of the first layer 4 and the second layer 5 contains the needle-shaped crystal pigment. However, from the viewpoint of more effectively improving the scratch resistance of the top plate 1, it is preferable that the second layer 5 contains the needle-shaped crystal pigment. From the viewpoint of more effectively suppressing the occurrence of breakage or cracks in the heat-resistant resin layer 3 due to volumetric shrinkage of the silicone resin, it is preferable that the first layer 4 contains the needle-shaped crystal pigment. It is more preferable that both the first layer 4 and the second layer 5 contain the needle-shaped crystal pigment.

[0033] The silicone resin is not particularly limited, but is preferably one having high heat resistance. For example, the silicone resin is preferably a silicone resin in which the functional group directly bonded to the silicon atom is at least one of a methyl group and a phenyl group. In this case, discoloration of the heat-resistant resin layer 3 when the top plate 1 is heated to a high temperature can be more effectively suppressed.

[0034] The content of the silicone resin contained in the first layer 4 and the second layer 5 is not particularly limited, but is preferably 20% by mass or more, more preferably 30% by mass or more, and preferably 70% by mass or less, more preferably 60% by mass or less. When the content of the silicone resin is equal to or greater than the above-mentioned lower limit, the heat resistance and impact resistance of the top plate 1 can be further improved. On the other hand, when the content of the silicone resin is equal to or less than the above-mentioned upper limit, the mechanical strength of the top plate 1 can be further improved.

[0035] A needle-shaped crystal pigment is a pigment having a needle-shaped crystal structure. In this specification, whether or not a pigment has a needle-shaped crystal structure can be confirmed by observing the shape using a scanning electron microscope, a transmission electron microscope, or the like. For example, the presence of a needle-shaped crystal structure can be confirmed from a photograph such as that shown in Figure 4.

[0036] The dimensions of the needle crystal pigment are not particularly limited. The length of the needle crystal pigment can be, for example, 5 μm or more and 60 μm or less, preferably 8 μm or more, more preferably 10 μm or more, preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. The width of the needle crystal pigment can be, for example, 0.1 μm or more and 7 μm or less, preferably 0.2 μm or more, preferably 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less. The aspect ratio of the needle crystal pigment can be, for example, 8 or more and 100 or less, preferably 10 or more, more preferably 20 or more, preferably 80 or less, more preferably 50 or less, and even more preferably 40 or less. The length, width, and aspect ratio of the needle crystal pigment can each be the average value of 50 needle crystal pigments observed using a scanning electron microscope. The aspect ratio of the needle crystal pigment refers to the ratio of the average length of the needle crystal pigment to the average width (average length / average width).

[0037] The needle crystal pigment is not particularly limited, but examples thereof include potassium titanate, calcium silicate, and titanium oxide. Among these, potassium titanate is preferred as the needle crystal pigment, as it can more effectively improve the scratch resistance of the top plate 1. Note that one type of needle crystal pigment may be used alone, or multiple types may be used in combination.

[0038] The pigment mass concentrations of the needle crystal pigment contained in the first layer 4 and the second layer 5 are not particularly limited, but are preferably 3% by mass or more, more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 30% by mass or less. When the needle crystal pigment content is within the above range, the scratch resistance of the top plate 1 can be more effectively improved. Note that the pigment mass concentration of the needle crystal pigment refers to the content of the needle crystal pigment contained in each of the first layer 4 and the second layer 5.

[0039] The first layer 4 and the second layer 5 may each contain a color pigment. In this case, the first layer 4 may contain a first color pigment, and the second layer 5 may contain a second color pigment different from the first color pigment. In this case, an appropriate combination of color pigments can be selected taking into consideration the design and the ability to conceal the inside of the cookware.

[0040] The color pigment is not particularly limited as long as it is a colored inorganic substance, and examples of the color pigment include white pigment powders such as TiO powder, ZrO powder, and ZrSiO powder, blue inorganic pigment powders containing Co, green inorganic pigment powders containing Co, Ti-Sb-Cr-based or Ti-Ni-based yellow inorganic pigment powders, Co-Si-based red inorganic pigment powders, brown inorganic pigment powders containing Fe, and black inorganic pigment powders containing Cu.

[0041] Specific examples of blue inorganic pigment powders containing Co include Co-Al-based and Co-Al-Ti-based inorganic pigment powders. Specific examples of Co-Al-based inorganic pigment powders include CoAl2O4 powder. Specific examples of Co-Al-Ti-based inorganic pigment powders include CoAl2O4-TiO2-Li2O powder.

[0042] Specific examples of green inorganic pigment powders containing Co include Co-Al-Cr and Co-Ni-Ti-Zn inorganic pigment powders. Specific examples of Co-Al-Cr inorganic pigment powders include Co(Al,Cr)2O4 powder. Specific examples of Co-Ni-Ti-Zn inorganic pigment powders include (Co,Ni,Zn)2TiO4 powder.

[0043] A specific example of the brown inorganic pigment powder containing Fe is an Fe—Zn-based inorganic pigment powder, such as (Zn,Fe)Fe2O4 powder.

[0044] Specific examples of black inorganic pigment powders containing Cu include Cu-Cr-based inorganic pigment powders and Cu-Fe-based inorganic pigment powders. Specific examples of Cu-Cr-based inorganic pigment powders include Cu(Cr,Mn)2O4 powder and Cu-Cr-Mn powder. Specific examples of Cu-Fe-based inorganic pigment powders include Cu-Fe-Mn powder.

[0045] These color pigments may be used alone or in combination of two or more.

[0046] The content of the color pigment contained in each of the first layer 4 and the second layer 5 is preferably 1% by mass or more, more preferably 3% by mass or more, and preferably 60% by mass or less, more preferably 45% by mass or less. The content of the color pigment contained in each layer is the content when the total material constituting each layer is taken as 100% by mass. When the content of the color pigment contained in each layer is equal to or greater than the above-mentioned lower limit, the design and the ability to conceal the inside of the cookware can be further improved. When the content of the color pigment in each layer is equal to or less than the above-mentioned upper limit, the heat resistance and impact resistance of the top plate 1 can be further improved.

[0047] The first layer 4 and the second layer 5 may each further contain a scaly pigment. Examples of scaly pigments that can be used include mica, talc, and aluminum, with mica or aluminum being preferred. Aluminum may be obtained by crushing a spherical or blocky three-dimensional shape in one direction. When the first layer 4 and the second layer 5 contain a scaly pigment, the scratch resistance of the top plate 1 can be further improved. In the present invention, even if the first layer 4 and the second layer 5 contain a scaly pigment, the non-oriented needle-shaped crystal pigments intertwine with each other and function as aggregates, providing resistance to vertical contraction forces, thereby more reliably preventing surface peeling of the heat-resistant resin layer 3.

[0048] The average particle diameter of the scaly pigment is not particularly limited, but can be, for example, 3 μm or more and 50 μm or less, preferably 5 μm or more and preferably 30 μm or less. The average particle diameter is the average particle diameter D measured by a laser diffraction particle size distribution analyzer. 50 This refers to the following.

[0049] The content of the scaly pigment in the first layer 4 and the second layer 5 is not particularly limited, but is preferably 1% by mass or more, more preferably 10% by mass or more, and is preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less. When the content of the scaly pigment is within the above range, the scratch resistance of the top plate 1 can be more effectively improved. The content of the scaly pigment is the content when the entire material constituting the first layer 4 and the second layer 5 is 100% by mass, respectively.

[0050] Furthermore, in the heat-resistant resin layer 3, the mass ratio of the scaly pigment to the needle crystal pigment (scaly pigment / needle crystal pigment) is preferably 10 or less, more preferably 5 or less, even more preferably 4 or less, and particularly preferably 3 or less. When the mass ratio (scaly pigment / needle crystal pigment) is within the above range, surface peeling of the heat-resistant resin layer 3 can be prevented and the scratch resistance of the top plate 1 can be more effectively improved. The lower limit of the mass ratio (scaly pigment / needle crystal pigment) can be, for example, 0.75.

[0051] The pigment mass concentration in the heat-resistant resin layer 3 is preferably 3% or more, more preferably 10% or more, and preferably 70% or less, more preferably 60% or less. When the pigment mass concentration in the heat-resistant resin layer 3 is within the above range, the scratch resistance of the top plate 1 can be more effectively improved. Note that the above pigment mass concentration refers to the mass proportion of all pigments in each of the first layer 4 and the second layer 5.

[0052] The thicknesses of the first layer 4 and the second layer 5 are not particularly limited, and are each preferably 5 μm or more, more preferably 8 μm or more, and preferably 50 μm or less, and more preferably 30 μm or less. When the thickness of each layer is within the above range, peeling of the heat-resistant resin layer 3 due to repeated heating and cooling can be more effectively prevented, the design and the ability to conceal the inside of the cookware can be further improved, and the scratch resistance of the top plate 1 can be more effectively improved.

[0053] The total thickness of the heat-resistant resin layer 3 is also not particularly limited, and is preferably 5 μm or more, more preferably 10 μm or more, and preferably 70 μm or less, and more preferably 30 μm or less. When the total thickness of the heat-resistant resin layer 3 is within the above range, peeling of the heat-resistant resin layer 3 due to repeated heating and cooling can be more reliably prevented, the design and the ability to conceal the inside of the cookware can be further improved, and the scratch resistance of the top plate 1 can be more effectively improved.

[0054] An example of a method for manufacturing the top plate 1 will now be described.

[0055] (Manufacturing method) In one example of a method for manufacturing the top plate 1, first, a paste containing a silicone resin precursor and a needle crystal pigment is prepared. The paste may contain a crosslinking agent and a curing catalyst. In particular, the paste preferably contains a curing catalyst. The paste may also contain a color pigment, a scaly pigment, a solvent, a viscosity adjuster, a leveling agent, an antifoaming agent, etc. In this embodiment, the first layer-forming paste and the second layer-forming paste are prepared separately.

[0056] The silicone resin precursor is not particularly limited, but is preferably one having high heat resistance. The silicone resin precursor is preferably, for example, a silicone monomer, silicone oligomer, or silicone resin in which the functional group directly bonded to the silicon atom is at least one of a methyl group and a phenyl group. In this case, discoloration of the heat-resistant resin layer 3 when the top plate 1 is heated to a high temperature can be more effectively suppressed. Among these, a silicone monomer, silicone oligomer, or silicone resin in which the functional group directly bonded to the silicon atom is a methyl group is more preferred.

[0057] The curing catalyst is not particularly limited, but examples thereof include metal chelate compounds such as aluminum chelate compounds, titanium chelate compounds, and zirconia chelate compounds, organic titanium compounds, iron-based metal salts, and zinc-based metal salts. Among these, the curing catalyst is preferably a metal chelate compound, and more preferably an aluminum chelate compound. In this case, when the top plate 1 is viewed from the cooking surface 2a side, stains on the back surface caused by adhesives or the like can be made less visible, and the scratch resistance of the heat-resistant resin layer 3 can be further improved. These curing catalysts may be used alone or in combination.

[0058] The ratio of the curing catalyst to the silicone resin precursor is not particularly limited, but is preferably a mass ratio of silicone resin precursor:curing catalyst of 100:0.1 to 100:20, more preferably 100:0.2 to 100:10. When the ratio of the curing catalyst to the silicone resin precursor is within the above range, stains on the back surface caused by adhesives or the like can be made less visible when top plate 1 is viewed from the cooking surface 2a side, and the scratch resistance of heat-resistant resin layer 3 can be further improved.

[0059] The needle crystal pigment, color pigment, and scale-like pigment may be any of those described in the section on the heat-resistant resin layer. The solvent is not particularly limited, but xylene, for example, may be used.

[0060] Next, a first layer forming paste is applied onto the rear surface 2b of the glass substrate 2. Subsequently, the glass substrate 2 on which the first layer forming paste has been applied is heated to dry the first layer forming paste and harden the silicone resin precursor, thereby forming the first layer 4. Depending on the composition of the first layer 4, firing may be further performed after drying.

[0061] Next, a paste for forming a second layer is applied onto the first layer 4. Subsequently, the glass substrate 2 on which the paste for forming a second layer has been applied onto the first layer 4 is heated to dry the paste for forming a second layer and harden the silicone resin precursor, thereby forming the second layer 5. This allows the heat-resistant resin layer 3 to be formed. Depending on the composition of the second layer 5, it may be further fired after drying.

[0062] The application speed and viscosity of the paste can be set appropriately depending on the content of the pigment contained in the heat-resistant resin layer 3. For example, when the content of the pigment in the heat-resistant resin layer 3 is high, it is preferable to decrease the viscosity of the silicone resin precursor by increasing the amount of solvent and to decrease the application speed of the paste.

[0063] The heating temperature of the paste can be, for example, 60° C. or higher and 200° C. or lower. The heating time can be 1 minute or higher and 30 minutes or lower.

[0064] The firing temperature can be, for example, 200° C. or higher and 450° C. or lower. The firing time can be, for example, 10 minutes or higher and 1 hour or lower.

[0065] [Second embodiment] 2 is a schematic cross-sectional view showing a top plate for a cooker according to a second embodiment of the present invention. As shown in Fig. 2, a top plate 21 has a single-layer heat-resistant resin layer 23 provided on a rear surface 22b of a glass substrate 22.

[0066] The heat-resistant resin layer 23 contains a silicone resin and a needle-like crystal pigment. The silicone resin and needle-like crystal pigment described in the first embodiment can be used as appropriate. The heat-resistant resin layer 23 may also contain a color pigment or a scale-like pigment, as in the first embodiment.

[0067] The pigment mass concentration of the needle crystal pigment contained in the heat-resistant resin layer 23 is not particularly limited, but is preferably 3% by mass or more, more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 30% by mass or less. When the content of the needle crystal pigment is within the above range, the scratch resistance of the top plate 21 can be more effectively improved. Note that the pigment mass concentration of the needle crystal pigment refers to the content of the needle crystal pigment contained in the heat-resistant resin layer 23.

[0068] When the heat-resistant resin layer 23 contains a color pigment, the content of the color pigment contained in the heat-resistant resin layer 23 is preferably 1% by mass or more, more preferably 3% by mass or more, and preferably 60% by mass or less, more preferably 45% by mass or less. The content of the color pigment contained in the heat-resistant resin layer 23 is the content when the entire material constituting the heat-resistant resin layer 23 is taken as 100% by mass. When the content of the color pigment contained in the heat-resistant resin layer 23 is equal to or greater than the above-mentioned lower limit, the design and the ability to conceal the inside of the cookware can be further improved. When the content of the color pigment in the heat-resistant resin layer 23 is equal to or less than the above-mentioned upper limit, the heat resistance and impact resistance of the top plate 21 can be further improved.

[0069] When the heat-resistant resin layer 23 contains a scaly pigment, the content of the scaly pigment in the heat-resistant resin layer 23 is not particularly limited, but is preferably 1% by mass or more, more preferably 10% by mass or more, and is preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less. When the content of the scaly pigment is within the above range, the scratch resistance of the top plate 21 can be more effectively improved. Note that the content of the scaly pigment is the content when the entire material constituting the heat-resistant resin layer 23 is taken as 100% by mass.

[0070] Furthermore, when the heat-resistant resin layer 23 contains a scaly pigment, the mass ratio of the scaly pigment to the needle crystal pigment (scaly pigment / needle crystal pigment) in the heat-resistant resin layer 23 is preferably 10 or less, more preferably 5 or less, even more preferably 4 or less, and particularly preferably 3 or less. When the mass ratio (scaly pigment / needle crystal pigment) is within the above range, surface peeling of the heat-resistant resin layer 23 can be prevented, and the scratch resistance of the top plate 21 can be more effectively improved. The lower limit of the mass ratio (scaly pigment / needle crystal pigment) can be, for example, 0.75.

[0071] The pigment mass concentration in the heat-resistant resin layer 23 is preferably 3% or more, more preferably 10% or more, and preferably 70% or less, more preferably 60% or less. When the pigment mass concentration in the heat-resistant resin layer 23 is within the above range, the scratch resistance of the top plate 21 can be more effectively improved. Note that the above pigment mass concentration means the mass proportion of all pigments in the heat-resistant resin layer 23.

[0072] The content of the silicone resin in the heat-resistant resin layer 23 is not particularly limited, but is preferably 20% by mass or more, more preferably 30% by mass or more, and preferably 70% by mass or less, and more preferably 60% by mass or less. When the content of the silicone resin is equal to or greater than the above-mentioned lower limit, the heat resistance and impact resistance of the top plate 21 can be further improved. When the content of the silicone resin is equal to or less than the above-mentioned upper limit, the scratch resistance of the heat-resistant resin layer 3 can be further improved.

[0073] The thickness of heat-resistant resin layer 23 is not particularly limited, and is preferably 5 μm or more, more preferably 10 μm or more, and preferably 50 μm or less, and more preferably 30 μm or less. When the overall thickness of heat-resistant resin layer 23 is within the above range, peeling of heat-resistant resin layer 23 due to repeated heating and cooling can be more reliably prevented, the design and the ability to conceal the inside of the cookware can be further improved, and the scratch resistance of top plate 21 can be more effectively improved.

[0074] The method for forming the heat-resistant resin layer 23 is not particularly limited and can be the same as that of the first embodiment. Specifically, first, a paste containing a silicone resin precursor and a needle crystal pigment is prepared. The paste may contain a curing catalyst or a crosslinking agent. The paste may also contain a color pigment, a scaly pigment, a solvent, a viscosity adjuster, a leveling agent, an antifoaming agent, etc. Next, the prepared paste is applied to the rear surface 22b of the glass substrate 22. Subsequently, the glass substrate 22 to which the paste has been applied is heated to dry the paste and harden the silicone resin precursor, thereby forming the heat-resistant resin layer 23. Depending on the composition of the heat-resistant resin layer 23, firing may be performed after drying.

[0075] In the top plate 21 of this embodiment, the heat-resistant resin layer 23 also contains a silicone resin and a needle crystal pigment, so that scratch resistance can be effectively improved.

[0076] The heat-resistant resin layer 23 may be formed of one resin layer as in this embodiment, but may also be formed of two resin layers as in the heat-resistant resin layer 3 of the first embodiment, or may be formed of three or more resin layers.

[0077] [Third embodiment] Fig. 3 is a schematic cross-sectional view showing a top plate for a cooker according to a third embodiment of the present invention. As shown in Fig. 3, in a top plate 31, an inorganic light-shielding layer 36 is provided on a rear surface 32b of a glass substrate 32. Furthermore, a heat-resistant resin layer 33 is provided on the inorganic light-shielding layer 36. Note that the heat-resistant resin layer 33 may be the same as the heat-resistant resin layer 23 of the second embodiment.

[0078] The inorganic light-shielding layer 36 is a light-shielding layer containing the aforementioned coloring pigment, and is provided for the purpose of concealing the internal structure of the cooker. Therefore, by providing the inorganic light-shielding layer 36 together with the heat-resistant resin layer 33, even if the coloring pigment ratio of each of the heat-resistant resin layer 33 and the inorganic light-shielding layer 36 is reduced, the combined pigment content of the heat-resistant resin layer 33 and the inorganic light-shielding layer 36 can be maintained or increased. This makes it possible to more effectively conceal the internal structure of the cooker when viewed from the cooking surface 32a side, and further enhance the aesthetic appeal of the top plate 31.

[0079] The inorganic light-shielding layer 36 is not particularly limited as long as it is made of an inorganic substance and has low transmittance to visible light. The inorganic light-shielding layer 36 can be formed, for example, by a layer containing a color pigment and glass. In this case, for example, a Cu-Cr-Mn-based black inorganic pigment can be used as the color pigment. Furthermore, for example, a BO-SiO glass powder can be used as the glass. The inorganic light-shielding layer 36 can also be formed by a metal film such as titanium.

[0080] In this embodiment, the inorganic light-shielding layer 36 is a porous film containing a color pigment and glass. While the inorganic light-shielding layer 36 is preferably a porous film, it may also be a dense film that is substantially void-free. If the inorganic light-shielding layer 36 is a dense film, the adhesive is less likely to seep toward the glass substrate 32, making stains less noticeable when viewed from the cooking surface 32a side.

[0081] The thickness of the inorganic light-shielding layer 36 is not particularly limited. The thickness of the inorganic light-shielding layer 36 can be appropriately set depending on, for example, the light transmittance, mechanical strength, or thermal expansion coefficient of the inorganic light-shielding layer 36. Note that the inorganic light-shielding layer 36 usually has a thermal expansion coefficient different from that of the glass substrate 32. For this reason, the inorganic light-shielding layer 36 may be damaged by repeated heating and cooling.

[0082] To further prevent this damage, it is preferable that the inorganic light-shielding layer 36 is thin. The thickness of the inorganic light-shielding layer 36 is preferably in the range of 1 μm or more and 15 μm or less, and more preferably in the range of 2 μm or more and 10 μm or less.

[0083] There are no particular limitations on the method for forming the inorganic light-shielding layer 36. The inorganic light-shielding layer 36 can be formed, for example, by the following method.

[0084] First, a solvent is added to a mixed powder of a color pigment and glass powder to form a paste. The obtained paste is applied to the rear surface 32b of the glass substrate 32 by screen printing or the like, and dried. Thereafter, the inorganic light-shielding layer 36 can be formed by firing. The firing temperature and firing time can be appropriately set depending on the composition of the glass powder used, etc. The firing temperature can be, for example, about 200°C to 900°C. The firing time can be, for example, about 10 minutes to 1 hour.

[0085] When the inorganic light-shielding layer 36 is made of a metal film, it can be formed by a sputtering method, a CVD method, or the like.

[0086] In the top plate 31 of this embodiment, the heat-resistant resin layer 33 also contains a silicone resin and a needle crystal pigment, so that scratch resistance can be effectively improved.

[0087] In this embodiment, a single heat-resistant resin layer 33 is provided on the inorganic light-shielding layer 36, but two or more heat-resistant resin layers may be provided on the inorganic light-shielding layer 36.

[0088] The present invention will be described in more detail below with reference to examples. However, the following examples are merely illustrative and are not intended to limit the scope of the present invention.

[0089] Example 1 First, a paste was prepared by mixing methylphenyl silicone resin (manufactured by Momentive, product number "TSR-145") as a silicone resin precursor, an aluminum chelate compound (manufactured by Shin-Etsu Chemical, product number "CAT-AC") as a curing catalyst, black inorganic pigment powder, potassium titanate (manufactured by Otsuka Chemical, product number "TISMOD": length 15 μm, width 0.5 μm, aspect ratio 30) as a needle crystal pigment, and xylene as a solvent in a mass ratio (silicone resin precursor:curing catalyst:inorganic pigment powder:needle crystal pigment:solvent) of 63:1:20:12:4 (pigment mass concentration: 46 mass%).

[0090] This paste was used as a glass substrate, which was a transparent crystallized glass plate (manufactured by Nippon Electric Glass Co., Ltd., product name "N-0", average linear thermal expansion coefficient at 30°C to 750°C: 0.5 × 10 -7 The resin was then screen-printed over the entire glass substrate (temperature: 100°C, thickness: 4 mm) to a thickness of 15 μm. This was then heated and dried at 300°C for 10 minutes. This resulted in the formation of one heat-resistant resin layer on the glass substrate, yielding a top plate.

[0091] 4 is a scanning electron microscope photograph of a cross section of the heat-resistant resin layer obtained in Example 1. As shown in FIG. 4, needle crystal pigments can be confirmed.

[0092] Example 2 A top plate was obtained in the same manner as in Example 1, except that a paste was prepared in which the ratio of silicone resin precursor: curing catalyst: color pigment powder: needle crystal pigment: solvent was 52:1:20:18:9, and the pigment mass concentration was 55%.

[0093] Example 3 A top plate was obtained in the same manner as in Example 1, except that titanium oxide (manufactured by Ishihara Sangyo Kaisha, Ltd., product number "FTL-300": length 8.5 μm, width 0.3 μm, aspect ratio 28) was used as the needle crystal pigment.

[0094] Example 4 A top plate was obtained in the same manner as in Example 2, except that calcium silicate (Ca silicate, manufactured by NYCO, product number "nyglos": length 40 μm, width 4 μm, aspect ratio 10) was used as the needle crystal pigment.

[0095] Example 5 A top plate was obtained in the same manner as in Example 1, except that a paste was prepared by mixing a methylphenyl silicone resin (manufactured by Momentive, product number "TSR-145") as a silicone resin precursor, an aluminum chelate compound (manufactured by Shin-Etsu Chemical, product number "CAT-AC") as a curing catalyst, black inorganic pigment powder, potassium titanate (manufactured by Otsuka Chemical, product number "TISMOD": length 15 μm, width 0.5 μm, aspect ratio 30) as a needle-shaped crystal pigment, mica (average particle diameter: 24 μm) as a scaly pigment, and xylene as a solvent in a mass ratio (silicone resin precursor: curing catalyst: inorganic pigment powder: needle-shaped crystal pigment: scaly pigment: solvent) of 63:1:20:3:9:4 (pigment mass concentration: 46 mass%, mass ratio (mica / potassium titanate): 9 / 3).

[0096] Examples 6 to 9 A top plate was obtained in the same manner as in Example 5, except that the pigment mass concentration and mass ratio (mica / potassium titanate) were changed as shown in Tables 1 and 2 below.

[0097] Example 10 A top plate was obtained in the same manner as in Example 5, except that aluminum (average particle diameter: 24 μm) was used as the scaly pigment.

[0098] (Comparative Example 1) A top plate was obtained in the same manner as in Example 1, except that no needle crystal pigment was used.

[0099] (Comparative Example 2) A top plate was obtained in the same manner as in Comparative Example 1, except that no curing catalyst was used.

[0100] (Comparative Example 3) A top plate was obtained in the same manner as in Example 1, except that mica (average particle size: 24 μm) was used as a scaly pigment instead of the needle crystal pigment.

[0101] (Comparative Examples 4 to 7) A top plate was obtained in the same manner as in Comparative Example 3, except that a scaly pigment was used and a paste was prepared so that the pigment mass concentration was as shown in Table 2 below.

[0102] [evaluation] The top plates obtained in Examples 1 to 10 and Comparative Examples 1 to 7 were evaluated as follows.

[0103] (Solvent resistance) The surface of the heat-resistant resin layer on the top plate was rubbed back and forth with a cloth soaked in a solvent, and then the surface condition was visually observed and evaluated according to the following criteria. 2 The number of rubbings was 10 times, and hexane and ethanol were used as solvents.

[0104] [Evaluation criteria] 1: The heat-resistant resin layer melted, exposing the glass substrate. 2: The surface of the heat-resistant resin layer has melted 3: Scratches occurred on the surface of the heat-resistant resin layer, and part of the surface of the heat-resistant resin layer peeled off. 4: The surface gloss of the heat-resistant resin layer has changed. 5: No change was observed on the surface of the heat-resistant resin layer

[0105] (Pencil hardness) The pencil hardness of the heat-resistant resin layer in the top plate was evaluated in accordance with JIS K5600-5-4 (1999).

[0106] (Heat resistance test) The condition of the heat-resistant resin layer was visually observed after the top plate was heated at 350°C for 3 hours, 27 hours, and 100 hours. In Tables 1 and 2, ○ indicates that no cracks or breaks were observed.

[0107] (Boiling water resistance test) The top plate was immersed in boiling water, kept at 95°C for 2 hours, and then removed and its appearance was observed. In Tables 1 and 2, a circle indicates that the appearance before immersion was maintained. * a * b * The color difference ΔE in the color system was measured. The color difference ΔE was evaluated using a color difference meter (Konica Minolta, Inc., "CM600d"). Regarding adhesion, after immersion, 11 vertical and horizontal cuts were made in the heat-resistant resin layer at 1 mm intervals with a cutter knife to create 100 grid-like cuts, and tape was applied to the cuts and peeled off to evaluate the state of peeling. In Tables 1 and 2, A indicates no peeling, B indicates peeling was observed only on the surface, and C indicates exposure of the glass substrate.

[0108] The results are shown in Tables 1 and 2 below. In addition to the total pigment concentration (pigment mass concentration) in the heat-resistant resin layer, Tables 1 and 2 below also show the content of the needle crystal pigment and the content of the scaly pigment in the heat-resistant resin layer, respectively.

[0109] [Table 1]

[0110] [Table 2]

[0111] As is clear from Tables 1 and 2, Examples 1 to 10, which used a needle crystal pigment, had high pencil hardness and no surface peeling of the heat-resistant resin layer, indicating that scratch resistance was effectively enhanced. On the other hand, Comparative Examples 1 and 2, which did not use a needle crystal pigment, did not have sufficiently enhanced pencil hardness. Furthermore, in Comparative Examples 3 to 7, which used a scaly pigment, surface peeling was observed, indicating that scratch resistance was not sufficiently enhanced. However, Examples 5 to 10, which used a combination of a needle crystal pigment and a scaly pigment, had high pencil hardness and no surface peeling of the heat-resistant resin layer, indicating that scratch resistance was effectively enhanced without a decrease in adhesion. [Explanation of symbols]

[0112] 1, 21, 31...Cooker top plate 2, 22, 32...Glass substrate 2a,22a,32a…Cooking surface 2b,22b,32b…Back side 3,23,33…Heat-resistant resin layer 4...First layer 5...Second layer 36...Inorganic light shielding layer

Claims

1. a glass substrate having a cooking surface on which a cooking utensil is placed and a back surface opposite the cooking surface; a heat-resistant resin layer disposed on the rear surface of the glass substrate; Equipped with The heat-resistant resin layer comprises a silicone resin, a needle-like crystal pigment, and a scale-like pigment.

2. 2. The top plate for a cooker according to claim 1, wherein the needle-shaped crystal pigment is at least one selected from the group consisting of potassium titanate, calcium silicate, and titanium oxide.

3. 3. The cookware top plate of claim 2, wherein the needle-shaped crystal pigment is potassium titanate.

4. 3. The top plate for a cooker according to claim 1, wherein the scaly pigment is mica or aluminum.

5. 3. The top plate for a cooker according to claim 1, wherein the heat-resistant resin layer has a pigment mass concentration of the needle crystal pigment of 3% or more and 50% or less.

6. The heat-resistant resin layer is a first layer including a first color pigment; a second layer disposed on the first layer and including a second color pigment different from the first color pigment; and The top plate for a cookware according to claim 1 or 2, wherein at least one of the first layer and the second layer contains the needle-shaped crystal pigment.

7. The cookware top plate of claim 6 , wherein the second layer comprises the needle-shaped crystal pigment.

8. A top plate for a cooker as described in claim 1 or 2, wherein in the heat-resistant resin layer, the mass ratio of the scale-like pigment to the needle-like crystal pigment (scale-like pigment / needle-like crystal pigment) is 0.75 or more and 4 or less.

Images