Cooker top plate and method for manufacturing cooker top plate

Abstract

Provided are a cooker top plate excellent in stain resistance, and a method for manufacturing the cooker top plate.　A cooker top plate (1) is characterized by comprising: a glass substrate (2) having a cooking surface (2a) on which cookware is placed and a rear surface (2b) on the reverse side of the cooking surface (2a); and a decorative layer (3) disposed on the cooking surface (2a) side of the glass substrate (2), the decorative layer (3) containing glass and a pigment, and the pigment containing an extender pigment with an average particle diameter of 1.5 μm or less and substantially not containing titanium oxide.

Description

Top plate for cooker and method for manufacturing the top plate for cooker

[0001] The present invention relates to a top plate for a cooker and a method for manufacturing a top plate for a cooker.

[0002] A cooker top plate is provided on the top of an induction cooker, a radiant heater cooker, a gas cooker, etc. Generally, the cooker top plate is provided with a transparent or opaque glass substrate having a cooking surface on which cookware is placed and a back surface opposite the cooking surface. A decorative layer may be provided on the cooking surface of the glass substrate to enhance the appearance of the cooker top plate.

[0003] For example, Patent Document 1 describes a top plate for a cooker having a decorative layer containing glass and refractory filler powder on the cooking surface side of a glass substrate.

[0004] When using a cookware, cooking utensils such as pots come into contact with the decorative layer on the cooking surface of the cookware top plate. For example, if the bottom of the pot is rubbed hard against the decorative layer, the paint on the bottom of the pot may peel off or the metal on the bottom of the pot may be scraped off, resulting in stains being transferred onto the decorative layer. The transferred stains significantly reduce the design of the cookware top plate.

[0005] JP 2016-156570 A

[0006] In recent years, consumers have become increasingly interested in design, and as a result, cookware top plates are required to have a decorative layer with excellent stain resistance, i.e., a coating that is resistant to dirt caused by peeling of the paint or metal of cookware, even when rubbed against the surface by pots and other cookware.

[0007] In view of the above, an object of the present invention is to provide a top plate for a cooker that is highly stain-resistant, and a method for manufacturing the top plate for a cooker.

[0008] The inventors believed that in order to improve the stain resistance of a decorative layer provided on the cooking surface of a glass substrate, the surface condition of the decorative layer (specifically, the surface roughness) should be appropriately controlled. Based on this idea, they adjusted the type and average particle size of the pigment in the decorative layer and found that it was possible to provide a top plate for a cooker with excellent stain resistance and a method for manufacturing such a top plate for a cooker.

[0009] That is, a top plate for a cookware according to Aspect 1 of the present invention comprises a glass substrate having a cooking surface on which a cookware is placed and a back surface opposite the cooking surface, and a decorative layer disposed on the cooking surface side of the glass substrate, the decorative layer comprising glass and a pigment, the pigment containing an extender pigment having an average particle size of 1.5 μm or less, and being substantially free of titanium oxide. Note that "substantially free" here means, for example, 0.05% by mass or less relative to 100% by mass of the decorative layer.

[0010] In a top plate for a cooker according to Aspect 2 of the present invention, in Aspect 1, it is preferable that the pigment further contains a coloring pigment other than titanium oxide, and that the decorative layer contains 60 to 99 mass% of the glass, 0.1 to 30 mass% of the coloring pigment, and 0.1 to 30 mass% of the extender pigment, relative to 100 mass% of the decorative layer.

[0011] In the top plate for a cookware according to Aspect 3 of the present invention, in Aspect 2, it is preferable that the extender pigment has a Mohs hardness of 5 or less.

[0012] In the top plate for a cookware according to Aspect 4 of the present invention, in Aspects 2 or 3, it is preferable that the extender pigment contains barium sulfate.

[0013] In a top plate for a cooker according to Aspect 5 of the present invention, in Aspect 4, it is preferable that the content of the barium sulfate in 100% by mass of the decorative layer is less than 20% by mass.

[0014] In the top plate for a cooker according to aspect 6 of the present invention, in aspect 4 or 5, it is preferable that the content of the barium sulfate and the content of the color pigment in 100% by mass of the decorative layer satisfy the relationship 0.1≦barium sulfate content / (barium sulfate content+color pigment content)≦0.85.

[0015] In the top plate for a cooker according to Aspect 7 of the present invention, in any one of Aspects 1 to 6, it is preferable that the decorative layer has an arithmetic mean roughness Ra of 0.72 μm or less.

[0016] A top plate for a cooker according to aspect 8 of the present invention comprises a glass substrate having a cooking surface on which a cookware is placed and a back surface opposite the cooking surface, and a decorative layer disposed on the cooking surface side of the glass substrate, the decorative layer comprising glass and a pigment, the pigment comprising a color pigment other than titanium oxide, and the arithmetic mean roughness Ra of the surface of the decorative layer being less than 0.61 μm.

[0017] The method for manufacturing a cooker top plate according to the present invention is a method for manufacturing a cooker top plate according to any one of Aspects 1 to 8, and is characterized by comprising the steps of: preparing a glass substrate having a cooking surface on which a cookware is placed and a back surface opposite the cooking surface; applying a paint onto the cooking surface of the glass substrate, the paint including glass frit and a pigment, the pigment including an extender pigment having an average particle size of 1.5 μm or less, and being substantially free of titanium oxide; and heating the glass substrate to which the paint has been applied, to form a decorative layer.

[0018] According to the present invention, it is possible to provide a top plate for a cooker having excellent stain resistance and a method for manufacturing the top plate for a cooker.

[0019] FIG. 1 is a schematic cross-sectional view showing a top plate for a cooker according to an embodiment of the present invention.

[0020] 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.

[0021] In this specification, the term "top plate for a cooking appliance" may be abbreviated to "top plate."

[0022] The top plate 1 for a cooker shown in Figure 1 includes a glass substrate 2. The glass substrate 2 has a cooking surface 2a and a back surface 2b. The cooking surface 2a and the back surface 2b are surfaces that face each other. The cooking surface 2a is the surface on which cookware such as pots and frying pans are placed. The back surface 2b is the surface that faces the light source and heating device inside the cooker. Therefore, the cooking surface 2a and the back surface 2b are in a front-back relationship. A decorative layer 3 is disposed on the cooking surface 2a of the glass substrate 2. The cooking surface 2a of the glass substrate 2 and the decorative layer 3 are in contact with each other.

[0023] The members and layers that make up the top plate 1 will be described in detail below.

[0024] (Glass Substrate) The glass substrate 2 is not particularly limited. The glass substrate 2 may be, for example, a white glass substrate or a transparent glass substrate. In this specification, the term "transparent" in relation to a glass substrate means that the light transmittance in the visible wavelength range of 450 nm to 700 nm is 70% or more.

[0025] The top plate 1 is repeatedly heated and cooled. Therefore, it is preferable that the glass substrate 2 has high thermal shock resistance and a low thermal expansion coefficient. Specifically, the softening temperature of the glass substrate 2 is preferably 700°C or higher, and more preferably 750°C or higher. The average linear thermal expansion coefficient of the glass substrate 2 at 30°C to 750°C is -10x10- ７ / ℃~+60×10- ７ / °C, and is preferably in the range of -10 x 10 - ７ / ℃~+50×10- ７ / °C, and more preferably within the range of -10 x 10 - ７ / ℃~+40×10- ７ / °C. Therefore, the glass substrate 2 is preferably made of glass or glass-ceramic that has a high glass transition temperature and low expansion. Specific examples of low-expansion glass-ceramic include LAS (Li ２ O-Al ２ O ３ -SiO ２)-based crystallized glass, such as "N-11" and "N-0" manufactured by Nippon Electric Glass Co., Ltd. Note that the glass substrate 2 may also be a borosilicate glass substrate.

[0026] There is no particular limitation on the thickness of the glass substrate 2. The thickness of the glass substrate 2 can be appropriately set depending on the output temperature and structure of the cooking device. The thickness of the glass substrate 2 can be, for example, about 2 mm to 6 mm.

[0027] (Decorative Layer) The decorative layer 3 is disposed on the cooking surface 2a of the glass substrate 2. The decorative layer 3 has a single-layer structure. However, the decorative layer 3 may have a two-layer structure or a three-layer or more layer structure as long as the stain resistance, which is the objective of the present invention, is not impaired. In this case, the ratio of the constituent components of each layer may be different or the same.

[0028] The decorative layer 3 contains glass and a pigment, the pigment containing an extender pigment with an average particle size of 1.5 μm or less and substantially free of titanium oxide. This appropriately controls the surface condition of the decorative layer 3 (specifically, the surface is smooth). Therefore, even if a cookware or other item rubs against the decorative layer, the peeled paint from the bottom of the cookware is less likely to adhere to the decorative layer 3 as a stain. In other words, a cookware top plate with excellent stain resistance can be achieved. While the reason why the inclusion of an extender pigment with an average particle size of 1.5 μm or less appropriately controls the surface condition of the decorative layer 3 is unclear, it is believed that the greater the amount of extender pigment with a smaller average particle size, the less likely it is to impede the flow of the molten glass frit, making the surface of the decorative layer 3 more easily smooth. Furthermore, titanium oxide is a pigment commonly used as a white coloring pigment. The inventors have found that the presence of titanium oxide in the decorative layer 3 tends to increase the arithmetic mean roughness (Ra) of the surface of the decorative layer 3. In other words, the absence of titanium oxide substantially facilitates the smoothing of the surface of the decorative layer 3.

[0029] The decorative layer 3 preferably contains glass, a color pigment other than titanium oxide, and an extender pigment having an average particle size of 1.5 μm or less, and more preferably contains 60 to 99 mass % of glass, 0.1 to 30 mass % of the color pigment other than titanium oxide, and 0.1 to 30 mass % of the extender pigment having an average particle size of 1.5 μm or less, when the entire material of the decorative layer 3 is taken as 100 mass %. This makes the decorative layer 3 a colored layer, and so, for example, when the decorative layer 3 functions as a display layer for displaying information, it can clearly display the information while also improving stain resistance.

[0030] The components contained in the decorative layer will be described below.

[0031] (Glass Component) The decorative layer 3 contains glass. That is, it has a glass matrix. Examples of the glass composition include borosilicate glass, aluminoborosilicate glass, silicate glass containing at least one of an alkali metal component and an alkaline earth metal component, and phosphate glass containing zinc and aluminum. The glass matrix may be made of one type of glass or two or more types of glass.

[0032] The glass content of the decorative layer 3 is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 75% by mass or more, and is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 95% by mass or less. Within the above range, the surface condition of the decorative layer 3 can be easily controlled appropriately, which makes it easier to improve stain resistance and scratch resistance.

[0033] (Pigment) The decorative layer 3 contains a pigment. The pigment includes an extender pigment having an average particle size of 1.5 μm or less. The average particle size of the extender pigment is preferably 1.2 μm or less, more preferably 1 μm or less, and particularly preferably 0.5 μm or less. When the average particle size of the extender pigment is equal to or less than the above upper limit, the surface condition of the decorative layer 3 can be easily controlled appropriately, thereby further improving the stain resistance of the decorative layer 3. There is no particular restriction on the lower limit of the average particle size of the extender pigment, but it is, for example, 0.005 μm or more, in which case the dispersibility of the pigment in the paint can be further improved.

[0034] The average particle size of the extender pigment is a median size derived from a volume distribution measured by a laser diffraction scattering method.

[0035] The Mohs hardness of the extender pigment itself is preferably not more than 5, more preferably not more than 4.5, even more preferably not more than 4, and particularly preferably not more than 3.5. If the Mohs hardness of the extender pigment is greater than the upper limit, the cookware will be more likely to be scraped when the decorative layer 3 comes into contact with the cookware, which will tend to reduce the stain resistance.

[0036] The shape of the extender pigment is not particularly limited, and may be scaly, spherical, needle-like, irregular, or the like.

[0037] Examples of the extender pigment include mica, talc, boron nitride, zinc oxide, glass beads, silica beads, and beads containing organic groups such as barium sulfate, phenylpolysiloxane, methylpolysiloxane, methylphenylpolysiloxane, and organically functionalized polysiloxane. Only one type of the extender pigment may be used, or two or more types may be used in combination. To further enhance the effects of the present invention, it is more preferable to include barium sulfate. Since barium sulfate has a Mohs hardness of 3, it is less likely to scratch the cookware when the decorative layer 3 comes into contact with the cookware.

[0038] The content of the extender pigment in the decorative layer 3 is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably less than 20% by mass, and is preferably 0.1% by mass or more, more preferably 1% by mass or more, and particularly preferably 3% by mass or more. When the content of the extender pigment is within the above range, the effects of the present invention can be further enhanced. Note that the content of the extender pigment is the content when the total material contained in the decorative layer 3 is taken as 100% by mass.

[0039] When the extender pigment in the decorative layer 3 is barium sulfate, the content of barium sulfate in the decorative layer 3 is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably less than 20% by mass, preferably 1% by mass or more, and more preferably 3% by mass or more. When the content of barium sulfate is within the above range, the effects of the present invention can be further enhanced. Note that the content of barium sulfate is the content when the total material contained in the decorative layer 3 is 100% by mass.

[0040] When the extender pigment in the decorative layer 3 is barium sulfate, the upper limit of the ratio of the barium sulfate content to the barium sulfate and glass contents in the decorative layer, i.e., barium sulfate content / (barium sulfate content+glass content), is preferably 0.5 or less, more preferably 0.3 or less, and even more preferably 0.2 or less, and the lower limit is preferably 0.01 or more, more preferably 0.03 or more, and even more preferably 0.05 or more. Within the above range, the surface condition of the decorative layer 3 can be easily controlled appropriately, and therefore, the stain resistance can be easily improved.

[0041] The pigment does not substantially contain titanium oxide, that is, the decoration layer 3 does not substantially contain titanium oxide, which can improve the smoothness of the surface of the decoration layer 3.

[0042] For example, when the decorative layer 3 is used as a display layer for displaying information, the pigment preferably contains a color pigment other than titanium oxide. This allows the information to be clearly visible even when the display layer is viewed from any angle. Titanium oxide has a strong effect of scattering ambient light from fluorescent lights, LEDs, etc. inside the cooker, making it difficult to see the information when the display layer is viewed from an angle.

[0043] The color pigment is not particularly limited as long as it is a colored inorganic substance. Examples of the color pigment include ZrO ２ Powder and ZrSiO ４Examples of the color pigment include white pigment powders such as powders, blue inorganic pigment powders containing Co, green inorganic pigment powders containing Co, Ti—Sb—Cr and 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. Only one type of the color pigments may be used, or two or more types may be used in combination.

[0044] Examples of blue inorganic pigment powders containing Co include Co-Al-based and Co-Al-Ti-based inorganic pigment powders. ２ O ４ Examples of Co-Al-Ti based inorganic pigment powders include CoAl ２ O ４ -TiO ２ -Li ２ O powder and the like.

[0045] Examples of green inorganic pigment powders containing Co include Co-Al-Cr and Co-Ni-Ti-Zn inorganic pigment powders. Examples of Co-Al-Cr inorganic pigment powders include Co(Al,Cr) ２ O ４ Examples of Co-Ni-Ti-Zn based inorganic pigment powders include (Co, Ni, Zn) ２ TiO ４ Examples include powder.

[0046] Examples of brown inorganic pigment powders containing Fe include Fe-Zn-based inorganic pigment powders. Examples of Fe-Zn-based inorganic pigment powders include (Zn, Fe)Fe ２ O ４ Examples include powder.

[0047] Examples of black inorganic pigment powders containing Cu include Cu-Cr inorganic pigment powders and Cu-Fe inorganic pigment powders. Examples of Cu-Cr inorganic pigment powders include Cu(Cr,Mn)2O4 powder and Cu-Cr-Mn powder. Examples of Cu-Fe inorganic pigment powders include Cu-Fe-Mn powder.

[0048] The average particle size of the color pigment is preferably 10 μm or less, more preferably 5 μm or less, particularly preferably 3 μm or less, and preferably 0.01 μm or more, more preferably 0.1 μm or more, particularly preferably 0.5 μm or more. When the average particle size of the color pigment is equal to or less than the upper limit, it becomes easier to properly control the surface condition of the decorative layer 3, thereby further improving the stain resistance of the decorative layer 3. When the average particle size of the color pigment is equal to or greater than the lower limit, it becomes possible to further improve the dispersibility of the color pigment in the paint.

[0049] The content of the color pigment in the decorative layer 3 is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, preferably 0.1% by mass or more, more preferably 1% by mass or more, and particularly preferably 3% by mass or more. When the content of the color pigment is within the above range, for example, when the decorative layer 3 is used as a display layer for displaying information, the effects of the present invention can be further enhanced while clearly displaying the information. Note that, in applications where transparency is required for the decorative layer 3, it is preferable that the color pigment is not contained. Note that the content of the color pigment is the content when the total material contained in the decorative layer 3 is 100% by mass.

[0050] The upper limit of the ratio of the barium sulfate content to the barium sulfate and color pigment content in the decorative layer, i.e., the barium sulfate content / (barium sulfate content + color pigment content), is preferably 0.85 or less, more preferably 0.8 or less, and even more preferably 0.78 or less, and the lower limit is preferably 0.05 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. If the ratio is below the upper limit, for example, when the decorative layer 3 is used as a display layer for displaying information, the information is more easily displayed clearly. On the other hand, if the ratio is above the lower limit, the stain resistance is more easily improved.

[0051] (Other Details of the Decorative Layer 3) The arithmetic mean roughness Ra of the decorative layer 3 is preferably 0.72 μm or less, more preferably 0.65 μm or less, even more preferably less than 0.61 μm, and particularly preferably 0.6 μm or less. The lower limit of the arithmetic mean roughness Ra is preferably 0.1 μm or more, preferably 0.2 μm or more, and even more preferably 0.3 μm or more. If it is greater than the upper limit, when a cooking utensil such as a pot rubs against the decorative layer 3, the metal or paint on the bottom surface of the cooking utensil is easily scraped off and adheres to the decorative layer 3 as dirt, which is undesirable. On the other hand, if it is less than the lower limit, when the cooking utensil rubs against the decorative layer 3, the contact area between the cooking utensil and the decorative layer 3 becomes too large, which increases the frictional force generated between the cooking utensil and the decorative layer 3, and therefore the stain resistance is likely to be reduced, which is undesirable.

[0052] The arithmetic mean roughness Ra can be measured using a Mitutoyo SJ-210 in accordance with JIS B0601:2001.

[0053] The Mohs hardness of the surface of the decorative layer 3 is preferably 3 to 7, more preferably 4 to 6, and particularly preferably 5 to 6. If the Mohs hardness of the surface of the decorative layer 3 is above the upper limit, the surface of the decorative layer 3 is likely to scrape the metal or paint on the bottom surface of the cookware, i.e., the stain resistance is likely to decrease. On the other hand, if the Mohs hardness is below the lower limit, the surface of the decorative layer 3 is likely to be scratched by the cookware, etc.

[0054] The Mohs hardness of the surface of the decorative layer 3 can be measured using a known Mohs hardness tester, for example, a Mohs hardness tester (MH-10R) manufactured by Narica Co., Ltd.

[0055] The thickness of the decorative layer 3 is preferably 0.1 to 20 μm, more preferably 1 to 10 μm, even more preferably 2 to 8 μm, and particularly preferably 3 to 7 μm. When the thickness is within the above range, the surface condition can be easily adjusted by adding a pigment with an average particle diameter of less than 0.1 μm, which makes it easier to improve stain resistance.

[0056] (Manufacturing Method of Top Plate for Cooking Appliance) The top plate 1 for cooking appliance can be manufactured by, for example, the following manufacturing method.

[0057] First, a paste containing glass frit and an extender pigment having an average particle size of 1.5 μm or less is prepared for forming the decorative layer 3. Next, the paste for forming the decorative layer 3 is applied to the surface of the glass substrate 2 that will become the cooking surface 2a, and then dried and baked.

[0058] The paste for forming the decorative layer 3 can be applied, for example, by screen printing. The drying temperature of the paste for forming the decorative layer 3 can be, for example, 50°C or higher and 150°C or lower. The drying time of the paste for forming the decorative layer 3 can be, for example, 5 seconds or higher and 50 hours or lower. The baking temperature of the paste for forming the decorative layer 3 can be, for example, 600°C or higher and 950°C or lower. The baking time of the paste for forming the decorative layer 3 can be, for example, 10 minutes or higher and 2 hours or lower.

[0059] In the first embodiment described above, as shown in FIG. 1, the configuration of the cooker top plate is described as comprising a glass substrate and a decorative layer disposed on the cooking surface of the glass substrate. However, in the cooker top plate of the present invention, a concealing layer may be disposed on the back surface of the glass substrate.

[0060] The decorative layer may be disposed over the entire cooking surface of the glass substrate (i.e., a solid coating), or may be disposed over a portion of the cooking surface and function as a display layer that displays information.

[0061] The effects of the present invention can also be achieved in a cooking device that includes a glass substrate having a cooking surface on which a cooking utensil is placed and a back surface opposite the cooking surface, and a decorative layer that is disposed on the cooking surface side of the glass substrate, the decorative layer containing glass and a pigment that contains a colored pigment other than titanium oxide, and the arithmetic mean roughness Ra of the surface of the decorative layer being less than 0.61 μm.

[0062] 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.

[0063] The following glass substrate was prepared: a transparent crystallized glass plate (Nippon Electric Glass Co., Ltd., "N-0"; average linear thermal expansion coefficient at 30°C to 750°C: 0.5 × 10- ７ / ℃, thickness: 4mm)

[0064] The following materials for the decorative layer were prepared. <Glass Components> Glass frit ("Frit NPF" manufactured by Nippon Electric Glass Co., Ltd., average particle size 3.5 μm) <Pigments> Extender pigments Barium sulfate A (average particle size 0.01 μm, Mohs hardness 3) Barium sulfate B (average particle size 0.03 μm, Mohs hardness 3) Barium sulfate C (average particle size 0.3 μm, Mohs hardness 3) Coloring pigments Black pigment (Cu-Cr-Mn oxide powder, average particle size 1.6 μm, Mohs hardness 7) White pigment (titanium oxide, average particle size 0.15 μm, Mohs hardness 7) <Resin Binder> (Example 1) Glass frit, barium sulfate B, black pigment, and resin binder were mixed in a mass ratio (glass frit:barium sulfate B:black pigment:resin binder) of 80:5:15:200 to prepare a paste for forming the decorative layer. Next, the decorative paste was screen-printed onto the cooking surface of a transparent crystallized glass plate in 0.5 mm wide lines spaced at 5 mm intervals, resulting in a thickness of approximately 3.7 μm after firing. The resulting decorative layer was then dried at 80°C for 1 minute and then fired at 830°C for 30 minutes to form a decorative layer. The resin binder was completely volatilized by the heat-drying process. Table 1 lists the content of each component in the decorative layer after drying and firing.

[0065] (Examples 2 to 9 and Comparative Examples 1 to 4) A top plate for a cooker was obtained in the same manner as in Example 1, except that the ratio of each component in the decorative layer was changed to that shown in Table 1 below and the thickness after firing was set to approximately 3 to 6 μm.

[0066] [Evaluation] (1) Stain resistance of decorative layer First, clay and sand were placed in a stainless steel pot with a bottom diameter of 200±10 mm, and the total weight was adjusted to 2.0 kg. Next, while the bottom of the stainless steel pot was in contact with the decorative layer, the stainless steel pot was moved back and forth over a distance of 50 mm at a speed of approximately 1 m / s, and this operation was repeated 100 times. After that, the decorative layer was visually observed, and the degree of dirt that had adhered to the bottom of the pot due to scraping (stain resistance) was evaluated according to the following index. <Stain resistance> ◯: No visible dirt was adhered. ×: Dirt was adhered.

[0067]

[0068] As is clear from Table 1, the top plates of Examples 1 to 9, which contained an extender pigment with an average particle size of 1.5 μm or less in the decorative layer and which were substantially free of titanium oxide, had higher stain resistance than the top plate of Comparative Examples 1 to 3, which did not contain an extender pigment with an average particle size of 1.5 μm or less, and Comparative Example 4, which contained titanium oxide.

[0069] 1. Cooking appliance top plate 2. Glass substrate 2a. Cooking surface 2b. Back surface 3. Decorative layer

Claims

1. A top plate for a cooker, comprising a glass substrate having a cooking surface on which a cooking appliance is placed and a back surface opposite to the cooking surface, and a decorative layer disposed on the cooking surface side of the glass substrate, wherein the decorative layer contains glass and a pigment, the pigment contains an extender pigment having an average particle diameter of 1.5 μm or less and substantially does not contain titanium oxide.

2. The top plate for a cooker according to claim 1, wherein the pigment further contains a coloring pigment other than titanium oxide, and in 100% by mass of the decorative layer, 60 to 99% by mass of the glass, 0.1 to 30% by mass of the coloring pigment, and 0.1 to 30% by mass of the extender pigment are contained.

3. The top plate for a cooker according to claim 2, wherein the extender pigment has a Mohs hardness of 5 or less.

4. The top plate for a cooker according to claim 2 or 3, wherein the extender pigment contains barium sulfate.

5. The top plate for a cooker according to claim 4, wherein the content of barium sulfate in 100% by mass of the decorative layer is less than 20% by mass.

6. The top plate for a cooker according to claim 4, wherein the content of barium sulfate and the content of the coloring pigment in 100% by mass of the decorative layer satisfy 0.1 ≦ content of barium sulfate / (content of barium sulfate + content of coloring pigment) ≦ 0.

85.

7. The top plate for a cooker according to claim 2 or 3, wherein the arithmetic mean roughness Ra of the surface of the decorative layer is 0.72 μm or less.

8. A top plate for a cooker, comprising a glass substrate having a cooking surface on which a cooking appliance is placed and a back surface opposite to the cooking surface, and a decorative layer disposed on the cooking surface side of the glass substrate, wherein the decorative layer contains glass and a pigment, the pigment contains a coloring pigment other than titanium oxide, and the arithmetic mean roughness Ra of the surface of the decorative layer is less than 0.61 μm.

9. A method for manufacturing a top plate for a cooker according to claim 1 or 2, comprising the steps of: preparing a glass substrate having a cooking surface on which a cooking appliance is placed and a back surface opposite to the cooking surface; applying a paint containing glass frit and a pigment on the cooking surface of the glass substrate, the pigment containing an extender pigment having an average particle diameter of 1.5 μm or less and substantially not containing titanium oxide; and forming a decorative layer by heating the glass substrate coated with the paint. A method for manufacturing a top plate for a cooker, characterized by comprising the above steps.

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