JP2010021111A - Glass top plate for heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass top plate for a heating cooker that has a sufficient obliterating power and exhibits a satisfactory pearl tone effect at low cost. <P>SOLUTION: The glass top plate for a heating cooker includes a substrate 2 made of translucent and low-expansion glass ceramics, and a pearl tone layer 3 laminated at a rear side surface 22 that is an opposite side surface of a cooking face 21 on the substrate 2. The glass top plate 1 has a light transmittance of 50% or less in a 760-830 nm wavelength region. Preferably, the pearl tone layer 3 is formed by painting and calcinating on the substrate 2 pearl tone paints in which the content of a pearl tone material is at least 10 mass% but no more than 30 mass%, silicon resin or siliceous sol is 10 to 30 mass%, and organic binder is at least 40 mass% but no more than 80 mass%. Preferably, a cladding layer that is formed by applying diluent solvent of organometallic compound followed by calcination is laminated on the pearl tone layer 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a glass top plate for a cooker that is disposed on an upper portion of a heating cooker.

  In recent years, with the spread of all-electric homes, the demand for electromagnetic cookers continues to expand. In such a background, the electromagnetic cooker has evolved into one having various functions, and the structure inside the apparatus has become complicated accordingly. For such reasons, it has become necessary to conceal the structure inside the electromagnetic cooker more than ever for the top plate for the electromagnetic cooker.

  In addition, there is a great demand for white-type kitchen counters equipped with electromagnetic cookers, and a white-type glass top plate for a heating cooker that expresses a pearly effect that is harmoniously harmonized with the counter is strongly desired. .

  And in patent document 1, the pearl tone coloring glass which can express a pearl tone effect by the structure which forms a pearl tone paint layer in translucent low expansion glass ceramics, and has the original intensity | strength of translucent low expansion glass ceramics Ceramics are described. And in patent document 1, the light-shielding property for concealing the structure inside an electromagnetic cooker was obtained by providing a light-shielding layer on the said pearl color paint layer. However, since the light-shielding layer has a colored characteristic by containing a noble metal, there is a problem that the manufacturing cost increases.

Japanese Patent No. 3758445

  The present invention has been made in view of such conventional problems, and is intended to provide a glass top plate for a heating cooker that has low cost, has sufficient hiding power, and exhibits a sufficient pearly effect. To do.

The present invention consists of a substrate made of translucent low expansion glass ceramics, and a pearl tone layer laminated on the back side which is the surface opposite to the cooking surface in the substrate,
The said glass top plate exists in the glass top plate for heating cookers characterized by the light transmittance being 50% or less in the wavelength range of 760-830 nm (Claim 1).

The glass top plate for a heating cooker is configured to provide a pearl tone layer on the back side surface of the substrate, and has a light transmittance of 50% or less in the visible light region 760 to 830 nm on the long wavelength side defined by JIS Z8120 (2001). It is.
That is, the glass top plate for a heating cooker of the present invention is formed not only by providing a pearl tone layer but also by limiting the transmittance of specific light to a specific value or less as described above. Thereby, sufficient pearl tone effect and shielding property can be ensured only by the pearl tone layer in a specific application of a glass top plate for a cooking device. And it can exhibit the color tone which utilized the color of the pearl tone layer at low cost, and can fully hide the structure inside a cooking appliance.

  The pearl tone layer is not affected by the color even when a coating layer, a protective layer, a carbon electrode, etc., which will be described later, are provided. Therefore, a glass top plate for a heating cooker in which only the color of the pearl tone layer is reflected can be obtained.

  Thus, according to the present invention, it is possible to provide a glass top plate for a heating cooker that has a low hiding cost, has a sufficient hiding power, and exhibits a sufficient pearly effect.

As described above, the glass top plate for a heating cooker of the present invention includes a substrate made of translucent low-expansion glass ceramics, and a pearl tone layer laminated on the back side that is the surface opposite to the cooking surface of the substrate. Consists of.
The translucent low expansion glass ceramic is not particularly limited as long as it is translucent and has a low expansion coefficient. For example, there is one in which a β-quartz solid solution is precipitated in the main crystal phase.

  The crystallinity of the translucent low expansion glass ceramics on which the β-quartz solid solution is deposited is, for example, about 70% by volume and the crystal size is 0.1 μm or less. The β-quartz solid solution exhibits a negative expansion characteristic and cancels out the positive expansion characteristic of the remaining glass phase, so that the thermal expansion coefficient becomes almost zero. The refractive index (nD) is 1.541, the size of the precipitated crystal of β-quartz solid solution is 0.1 μm or less, which is smaller than the wavelength of visible light, and the refractive indices of the crystal phase and the remaining glass phase are almost the same. Therefore, there is no scattering of light, it is transparent in appearance, and transmits light from the visible light region to the infrared region well.

The pearl tone layer may be composed of only one layer, but may be laminated in two or more layers.
Further, the pearl tone layer is not necessarily provided on the entire back side surface, and can be formed in a desired pattern.

Moreover, it is preferable that the film thickness of the said pearl tone layer exists in the range of 3-30 micrometers.
When the film thickness of the pearl tone layer is less than 3 μm, the transmissivity may be high, and the structure inside the device may not be sufficiently concealed because it does not have a sufficient concealing power. On the other hand, when the film thickness of the pearl tone layer exceeds 30 μm, the pearl tone layer may be peeled off due to a difference in thermal expansion. The film thickness of the pearl tone layer is more preferably 5 to 15 μm.

The glass top plate has a light transmittance of 50% or less in a wavelength range of 760 to 830 nm.
When the light transmittance exceeds 50%, sufficient hiding power cannot be obtained.

  The pearl tone layer of the glass top plate for a heating cooker has a pearl tone material content of more than 10% by mass and 30% by mass or less, a silicone resin or siliceous sol of 10 to 30% by mass, and an organic binder of 40% by mass. It is preferable that a pearl-colored paint that is not less than 80% by mass and less than 80% by mass is fired with a picture on the substrate (claim 2).

  In this case, by providing the pearl tone layer using the pearl tone paint having the above specific composition, the glass for the heating cooker has a sufficient hiding power and exhibits a sufficient pearl tone effect at low cost. A top plate can be obtained.

  Since the said pearl color paint contains the said pearl-like material more than 10 mass% and 30 mass% or less, it can express sufficient pearl tone effect in the said glass top plate for cookers. Moreover, sufficient hiding power can be imparted.

  The pearl tone paint contains the specific amount of silicone resin or siliceous sol. These serve as a binding material for bonding between the pearl color paint and the substrate, and can be a pearl layer having excellent durability that can withstand an impact from a cooking surface, a thermal shock, or the like.

  Further, the specific amount of the organic binder contained in the pearl-colored paint imparts fluidity to the pearl-colored paint that contains a relatively large amount of the pearl-colored material. It is possible to suppress defects such as scumming and obtain good paintability.

  That is, by adding a specific amount of the silicone resin or siliceous sol and the organic binder to the pearl tone paint, a large amount of pearl tone material can form a pearl tone layer that adheres well to the substrate. it can. Therefore, it has a sufficient pearl tone effect, a sufficient hiding power, and a strength with no practical problem.

  Moreover, when forming the said pearl tone layer using the said pearl tone paint, since it consists of a pearl tone material, a silicone resin or a siliceous sol, and an organic binder, it can obtain at low cost.

The pearl tone material is, for example, coated with an inorganic pigment with titanium oxide, zirconium oxide, iron oxide or the like. The color of the inorganic pigment may be any number, and the pearl tone material exhibits a color obtained by adding a pearl tone to the color.
The inorganic pigment is not particularly limited, but kaolin, talc, sericite, pyroferrite, natural mica, synthetic mica, aluminum oxide and the like are preferably used.

  Moreover, a well-known technique can be used for coating methods, such as a titanium oxide, a zirconium oxide, and an iron oxide. For example, when coating titanium oxide with mica as an inorganic pigment, the mica powder is suspended in a dilute titanic acid aqueous solution, heated to 70 to 100 ° C., and the titanium salt is hydrolyzed to mica powder. There is a method in which hydrated titanium oxide particles are deposited on the surface and then fired at a high temperature of 700 ° C to 1000 ° C.

  Moreover, when content of the said pearl tone material is 10 mass% or less, there exists a possibility that sufficient concealment power cannot be exhibited. On the other hand, when the content of the pearl-like material exceeds 30% by mass, the amount of the organic binder decreases, and the viscosity as a paste deteriorates. There is a risk that problems such as unevenness and blurring may occur in film formation. Or there exists a possibility that content of the said silicone resin or siliceous sol may fall, and the adhesive force of a pearl tone layer and a board | substrate may fall remarkably.

The silicone resin refers to a polymer of an organosilicon compound having a siloxane bond as a main skeleton. If necessary, an organic solvent in which the silicone resin can be dissolved is used.
As the siliceous sol, for example, a silica sol obtained by hydrolyzing ethyl silicate or the like, a colloidal silica sol, or the like can be used.

  Further, when the content of the silicone resin or siliceous sol is less than 10% by mass, the adhesion between the pearly layer and the substrate may be significantly reduced. On the other hand, when the content of the silicone resin or siliceous sol exceeds 30% by mass, the silicone resin or siliceous sol may cover the pearl tone material, and the pearl tone effect may be reduced. Moreover, the ratio of the pearl tone material in a pearl tone paint will fall, and there exists a possibility that the transmittance | permeability may exceed 50%. Or, since the amount of the organic binder is reduced and the viscosity as a paste is deteriorated, there is a possibility that problems such as unevenness and blurring may occur in the coating film formation on the translucent low expansion glass ceramic. is there.

  As the organic binder, for example, an acrylic resin, an amide resin, an alkyd resin, a cellulose resin, or the like can be used. Moreover, you may add an organic solvent as needed.

In addition, when the content of the organic binder is less than 40% by mass, a paste having fluidity cannot be obtained, and in the formation of a coating film on the translucent glass ceramic, problems such as unevenness and scumming occur. There is a possibility. On the other hand, when the content of the organic binder exceeds 80% by mass, a fluid paste can be obtained, but the ratio of the pearl-like material is reduced, and the possibility that the pearl-like material cannot be obtained or the transmittance is low. May exceed 50%. Or there exists a possibility that content of the said silicone resin or siliceous sol may fall, and the adhesive force of a pearl tone layer and a board | substrate may fall remarkably.
In addition, also when forming the said pearl tone layer in multiple layers, the said baking is sufficient once.

  Further, in order to adjust the color of the pearl tone material, an inorganic pigment may be added to the pearl tone paint in a weight of 50% or less with respect to the weight of the pearl tone material. However, when an inorganic pigment is contained, the content of the powder combining the pearl material and the inorganic pigment should not exceed 30% by mass.

Examples of the inorganic pigment include a white inorganic pigment, a black inorganic pigment, a gray inorganic pigment, a yellow inorganic pigment, a brown inorganic pigment, a green inorganic pigment, a blue inorganic pigment, and a pink inorganic pigment.
Specifically, examples of the white inorganic pigment include TiO ₂ , ZrO ₂ , ZrSiO ₄ , Al ₂ O ₃ , 3Al ₂ O ₃ -2SiO ₂ , and Al ₂ TiO ₅ .

Examples of the black inorganic pigment include Cr-Fe-based oxides, Co-Mn-Cr-Fe-based oxides, Co-Ni-Cr-Fe-based oxides, and Co-Ni-Cr-Fe-Mn-based materials. An oxide etc. are mentioned.
Examples of the gray inorganic pigment include Sn-Sb-based oxides and Sn-Sb-V-based oxides.

Examples of the yellow inorganic pigment include Sn-V oxides, Zr-V oxides, Zr-Si-Pr oxides, Ti-Cr-Sb oxides, and the like.
Examples of the brown inorganic pigment include Zn-Al-Cr-Fe-based oxides and Zn-Mn-Al-Cr-Fe-based oxides.

Examples of the green inorganic pigment include Ca—Cr—Si oxides, Cr—Al oxides, Co—Zn—Al—Cr oxides, and Zr—Si—Pr—V oxides. It is done.
Examples of the blue powder include Co—Al—Zn-based oxides, Co—Al-based oxides, and Zr—Si-based oxides.
Examples of the pink inorganic pigment include Mn—Al oxides, Ca—Sn—Si—Cr oxides, Sn—Cr oxides, and Zr—Si—Fe oxides.
These pigments can be mixed in an arbitrary ratio so as to obtain a desired color.

  When an inorganic pigment is contained in the pearl-colored paint, the content of the inorganic pigment is 7.5% at the maximum when the pearl-like material is 15%. When the content of the powder including the pearly material and the inorganic pigment is 30% by mass, the content of the inorganic pigment is 10% at the maximum.

And when making a pearl tone paint contain an inorganic pigment, when content of the said inorganic pigment exceeds 50%, there exists a problem that a pearl tone falls.
In addition, when the content of the powder combining the pearl tone material and the inorganic pigment exceeds 30% by mass, the content of the silicone resin or the siliceous sol is decreased, and the adhesion between the pearl tone layer and the substrate is reduced. Because the content of the organic binder is reduced and the viscosity of the paste is deteriorated, the coating film is formed on the translucent glass ceramic. There is a possibility that.

Moreover, it is preferable that the said glass top plate for heating cookers has the coating layer formed by apply | coating and baking the diluted solution of an organometallic compound on the said pearl tone layer (Claim 3).
In this case, heat resistance can be imparted to the glass top plate for a heating cooker.

  Examples of the diluted solution of the organometallic compound include Au, Pt, Pd, Rh, Ru, Bi, Sn, Ni, Fe, Cr, Ti, Ca, Si, Ba, Sr, Mg, Ag, Zr, In, Examples include diluted solutions of organometallic compounds such as Mn, Zn, and Al. These dilute solutions of organometallic compounds may be used alone or in combination at a desired ratio.

  In addition, the said glass top plate for heating cookers acquires sufficient light-shielding property by the said pearl tone layer. Therefore, the coating layer hardly affects the expression of the pearl effect by the pearl layer. The covering layer is not intended to improve the light-shielding property, but mainly to protect the pearl tone layer. Therefore, the coating layer is not particularly limited and does not need to be darkly opaque. And it is preferable to have colored or colorless and highly transparent color tone after firing. In this case, for example, no precious metal components such as Au, Pt, Pd, Rh, and Ag are contained or extremely reduced. Therefore, the effect of reducing the manufacturing cost can be expected.

Moreover, the said coating layer can be formed by apply | coating the diluted solution of the said organometallic compound on the said pearl tone layer, and baking. The application of the diluted solution of the organometallic compound is preferably performed by screen printing.
The coating layer may be fired simultaneously with the pearl tone layer, or may be separately fired after firing the pearl tone layer.

  In an electromagnetic cooker with high function, there are some which have only a narrow gap because the internal parts approach the glass top plate. In such a case, for example, there is a risk of causing a wear mark on the pearl tone layer or the coating layer laminated on the back side surface of the glass top plate due to vibration during transportation.

Therefore, it is preferable that a protective layer formed by applying and baking a heat-resistant resin or a heat-resistant resin and an inorganic pigment is laminated on the pearl tone layer or the coating layer.
In this case, the protective effect which suppresses the damage of the back side surface of the said glass top plate for heating cookers can be acquired.
In addition, the said protective layer hardly influences the expression of the pearl tone effect by the pearl tone layer mentioned above.

The protective layer is preferably formed by applying a heat-resistant resin or a paste made of a heat-resistant resin and an inorganic pigment on the pearl tone layer or the coating layer and baking at 200 to 450 ° C.
The paste is preferably applied by screen printing.
Moreover, the said paste may contain an organic solvent and an inorganic pigment as needed.

When the baking temperature is less than 200 ° C., the heat-resistant resin layer is hardly baked sufficiently, and the heat-resistant resin layer is easily peeled after baking, and the function as a protective layer may not be sufficiently exhibited. On the other hand, when the calcination temperature exceeds 450 ° C., the heat-resistant resin disappears and the protective effect may be lost.
The firing temperature is more preferably 250 to 400 ° C.

The heat resistant resin is preferably a silicone resin, a polyamide resin, a fluororesin, or a composite thereof. In this case, the above-described protective effect can be obtained particularly well.
Moreover, when it contains an inorganic pigment, it is preferable that the content is 50 mass% or less. When the content of the inorganic pigment exceeds 50% by mass, the heat-resistant resin becomes insufficient, the adhesion may be lowered, and it becomes difficult to exhibit the above function.
Further, the protective layer is not necessarily formed on the entire back side surface, and may be formed in a desired pattern in a place that is easily affected by wear.

In recent years, a glass touch type top surface operation type electromagnetic cooker that enables main operations on the cooking surface of the electromagnetic cooker has become widespread.
Therefore, it is preferable that a carbon electrode made of a conductive carbon paste is formed on the pearl tone layer, the coating layer, or the protective layer as a wiring circuit of the touch operation panel. .
The carbon electrode may be formed in accordance with a required place. By forming the carbon electrode in a portion corresponding to the switch on the back side surface, it becomes possible to cope with the top surface operation.

The conductive carbon paste contains spherical and flaky graphite powder and acetylene black as a conductive material, and contains a polyester silicone resin as a vehicle, and the spherical graphite powder, flaky graphite powder, acetylene black, When the total content of the polyester silicone resin is 100 parts by weight, the conductive carbon paste contains 15 to 25 parts by weight of the spherical graphite powder, 15 to 25 parts by weight of the flaky graphite powder, and the acetylene. The conductive carbon paste having an average particle size of 10 μm to 20 μm is used for the spherical and scaly graphite powders containing 10 to 20 parts by weight of black and 40 to 55 parts by weight of the polyester silicone resin. preferable.
In this case, in the wiring circuit of the touch operation panel of the electromagnetic cooker, it is assumed that the wiring circuit becomes high temperature, but when the wiring circuit is formed using the conductive carbon paste, the heat resistance is excellent. The characteristics can be maximized.

In addition, in a touch operation panel of an electromagnetic cooker, there is a possibility that a wiring circuit formed of carbon paste may be peeled off due to wear, but the conductive carbon paste has excellent adhesion, so that Rarely happen.
Further, the conductive carbon paste can be adhered with sufficient adhesion strength to a resin layer such as silicone.

Moreover, it is preferable that the decoration layer which consists of a glass composition or a glass composition, and an inorganic pigment is laminated | stacked on the cooking surface of the said board | substrate partially or the whole surface (Claim 6).
In this case, the effect of preventing the cooking surface from being damaged by wear of the heated object such as a pan and the cooking surface of the glass top plate for a heating cooker, or obtaining the effect of making the heated object difficult to slip. Can do.
Moreover, diversity can be imparted to the design.

Moreover, it is preferable that the ratio which occupies for the said painting glass decoration layer to the said cooking surface is 80% or less. In this case, the wear strength can be maintained without impairing the design. When the area occupied by the decorative glass decorative layer exceeds 80%, the exposed portion of the cooking surface of the glass top plate for a cooker becomes small, which may reduce the design.
The occupied area of the decorative glass decorative layer is more preferably 50% or less.

Moreover, it is preferable that the said decorating glass decoration layer is 1-15 micrometers in thickness. When the film thickness of the decorative glass decorative layer is less than 1 μm, the above-described effects may not be sufficiently obtained. On the other hand, when the film thickness of the said decorative glass decoration layer exceeds 15 micrometers, there exists a possibility that the said decorative glass decoration layer may peel.
The film thickness of the decorative glass decorative layer is more preferably 2 to 10 μm.

The glass composition is preferably a lead-free glass composition in consideration of recyclability and the like.
Moreover, it is preferable that the said glass composition is 650 degrees C or less in a softening point. The glass composition contains SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , Li ₂ O, and K ₂ O as essential components, and Na ₂ O, CaO, SrO, BaO, as necessary. It is more preferable to use a lead-free glass composition that contains one or more of ZnO, TiO ₂ , and ZrO ₂ as an additive component and is welded by heat treatment at 750 to 900 ° C.
The inorganic pigment described above can be used as the inorganic pigment.

Moreover, it is preferable that the said decoration glass decoration layer is formed so that it may become an arbitrary pattern.
In this case, the wear strength can be maintained without impairing the design.
Examples of the arbitrary pattern include a dot shape, a line shape, and a stone shape having a certain area.

Example 1
In this example, a glass top plate for a cooking device according to an embodiment of the present invention will be described with reference to FIG.
The glass top plate 1 for a heating cooker of this example includes a substrate 2 made of translucent low expansion glass ceramics, and a pearl tone layer 3 laminated on a back side 22 which is a surface opposite to the cooking surface 21 of the substrate 2. It consists of. The glass top plate 1 has a light transmittance of 50% or less in a wavelength range of 760 to 830 nm.
This will be described in detail below.

In preparing the glass top plate 1 for a heating cooker, first, as the substrate 2, a light-transmitting low expansion crystallized glass ceramic (Neoceram N-0) having a β-quartz solid solution as a main crystal was prepared.
Further, as the pearl color paint, a pearl color paint comprising 20% by mass of a commercially available white pearl color material (particle size 4 to 50 μm), 15% by mass of silicone resin and 65% by mass of acrylic resin was prepared.

Thereafter, the pearl color paint was further printed on the substrate 2 with a stainless steel 250 mesh. Thereafter, it was baked at 850 ° C. to form a pearl tone layer 3 to produce a glass top plate 1 for a heating cooker.
The glass top plate 1 for a heating cooker obtained in this example exhibited a white pearly tone reflecting the color of the pearly tone layer.

  Thus, according to this example, it can be seen that it is possible to provide a glass top plate for a heating cooker that has a low hiding cost, has a sufficient hiding power, and exhibits a sufficient pearly effect.

(Example 2)
In this example, as shown in FIG. 2, the pearl tone layer 3 in Example 1 is changed to a pearl tone layer 302 composed of two layers.
Specifically, a pearl-colored paint similar to the pearl-colored paint of Example 1 was printed on a substrate 2 similar to the substrate of Example 1 in two layers with a 250 mesh stainless steel. Thereafter, it was baked at 850 ° C. to form a pearl tone layer 302 composed of two layers, and a glass top plate 102 for a heating cooker was produced.
The glass top plate 102 for a heating cooker obtained in this example exhibited a white pearly tone reflecting the color of the pearly layer.

(Example 3)
In this example, as shown in FIG. 3, the coating layer 4 is laminated on the pearl tone layer 302 of the glass top plate 102 for a heating cooker obtained in the second embodiment.
Specifically, a diluted solution of organometallic oxide composed of Zr and Bi was printed on stainless steel 250 mesh on the pearl tone layer 302 of the glass top plate 102 for a heating cooker obtained in Example 2 above. Thereafter, it was fired again at 850 ° C. to form the coating layer 4, and a glass top plate 103 for a heating cooker was obtained. The coating layer 4 had a thickness of 2 μm.
The glass top plate 103 for a heating cooker obtained in this example exhibited a white pearl tone reflecting only the color of the pearl tone layer.

Example 4
In this example, as shown in FIG. 4, a protective layer 5 is formed on the coating layer 4 of the glass top plate 103 for a heating cooker obtained in Example 3 above.
Specifically, a material composed of 70% by mass of silicone resin and 30% by mass of black inorganic pigment was printed on stainless steel 250 mesh on the coating layer 4 of the glass top plate 103 for a heating cooker obtained in Example 3 above. Then, it was cured at 200 ° C. to form the protective layer 5, and a glass top plate 104 for a heating cooker was produced. The protective layer 5 had a thickness of 5 μm.
The glass top plate 104 for a heating cooker obtained in this example exhibited a white pearly tone reflecting only the color of the pearly tone layer.

(Example 5)
In this example, as shown in FIG. 5, the decorative layer 6 is formed on the cooking surface 21 of the substrate 2 of Example 4 and the carbon electrode 7 is formed on the protective layer 5.
In producing the glass top plate 105 for a heating cooker of this example, first, as a paste material for a decoration layer, a paste in which 80% by mass of glass flux, 100% by mass of an organic binder, and 20% by mass of an inorganic pigment are mixed. Materials were prepared.
Here, as the glass flux, a SiO ₂ 65 wt%, the Al ₂ O ₃ 5 wt%, B ₂ O ₃ of 23 wt%, 1 wt% of Li ₂ O, and Na ₂ O 2 wt% , ₂ % by mass of K ₂ O, 1% by mass of TiO ₂ and 1% by mass of ZrO ₂ were used. Further, acrylic resin was used as the organic binder, and titanium oxide powder was used as the inorganic pigment.

  In addition, a conductive carbon paste made of a conductive material and a vehicle was prepared as the conductive carbon paste. The conductive carbon paste contains 15 to 25 parts by weight of spherical graphite powder, 15 to 25 parts by weight of scaly graphite powder, and 10 to 20 parts by weight of acetylene black as the conductive material, and polyester as the vehicle. Contains 40 to 55 parts by weight of silicone resin. The average particle size of the graphite powder is 15 μm.

Specifically, the conductive carbon paste is prepared as follows.
First, spherical graphite powder, scaly graphite powder, and acetylene black were prepared as conductive materials. As the spherical graphite powder and the scaly graphite powder, those having an average particle diameter of 15 μm were used. In addition, a polyester silicone resin was prepared as a vehicle. In this example, “KR-5230” manufactured by Shin-Etsu Chemical Co., Ltd. was used as the polyester silicone resin.
Next, 19 parts by weight, 19 parts by weight, 15.5 parts by weight, and 46.5 parts by weight of the spherical graphite powder, scaly graphite powder, acetylene black, and polyester silicone resin prepared above were mixed. A conductive carbon paste was prepared.

Then, the paste material for the decoration layer is made of stainless steel 350 mesh, φ0.8 mm, pitch 3... On the heater portion where the cooking device of the cooking surface 21 of the substrate 2 similar to the substrate 2 of Example 1 is installed. Printing was performed in the form of dots aligned at 5 mm. Thereafter, the decorative layer 6 was formed by baking at 850 ° C. The decorative layer had a thickness of 3 μm.
Thereafter, in the same manner as in Example 4, the pearl tone layer 302, the coating layer 4, and the protective layer 5 were formed on the back side surface 22 of the substrate 2.

Further, the conductive carbon paste is printed with a stainless steel 250 mesh on the portion corresponding to the glass touch switch on the back side surface 22 (on the protective layer 5), and then cured at 250 ° C. to form the carbon electrode 7 for a heating cooker. A glass top plate 105 was obtained.
The glass top plate for a heating cooker obtained in this example exhibited a pearly tone with a white taste reflecting only the color of the pearly tone layer.

(Comparative Example 1)
In this example, a glass top plate for a heating cooker as a comparative example of the present invention will be described.
In producing the glass top plate for the heating cooker of this example, first, 5% by mass of the pearl-like material similar to that of Example 1 and 15% by mass of the silicone resin similar to the silicone resin of Example 1; A pearl-colored paint composed of 80% by mass of an acrylic resin similar to the acrylic resin of Example 1 was prepared.

Next, the pearl color paint was printed on the back side surface of the same substrate as the substrate of Example 1 using stainless steel 250 mesh. Then, it baked at 850 degreeC, the pearl tone layer was formed, and the glass top plate for heating cookers was obtained.
The glass top plate for a heating cooker in this example exhibited a transparent pearl tone.

(Comparative Example 2)
This example is an example in which the pearl tone layer of the glass top plate for a heating cooker in Comparative Example 1 is changed to a pearl tone layer composed of two layers.
Specifically, on the same substrate as the substrate of Comparative Example 1, the same pearl-colored paint as that of Comparative Example 1 was printed in two layers with a stainless 250 mesh. Thereafter, it was baked at 850 ° C. to form a pearl layer composed of two layers, and a glass top plate for a heating cooker was produced.
The glass top plate for the heating cooker of this example exhibited a transparent pearl tone.

(Comparative Example 3)
This example is an example in which a light shielding layer is further laminated on the glass top plate for a cooker obtained in Comparative Example 2 above.
Specifically, black raster paste LU1404 (trade name) was applied onto the pearl tone layer of the glass top plate for a cooker obtained in Comparative Example 2 using a stainless steel 250 mesh. Then, it baked again at 850 degreeC, the light shielding layer was formed, and the glass top plate for heating cookers was obtained. The light shielding layer had a thickness of 2 μm.
The glass top plate for a heating cooker obtained in this example exhibited a pearly silver gray in which the color of the light shielding layer affected the pearly effect of the pearly layer.

(Experimental example 1)
About the glass top plate for heating cookers obtained in the said Example 1- Example 5 and the said comparative example 1- Comparative example 3, the film thickness of a pearl tone layer, the glass top plate for heating cookers in the wavelength of 760 nm and 830 nm The transmittance and brightness were measured, and the concealability of the internal components of the electromagnetic cooker was evaluated.

<Pearl layer thickness>
The film thickness of the pearl tone layer was measured using SEM (scanning electron microscope). The results are shown in Table 1.

<Transmissivity>
The transmittance was measured using JASCO V-570 manufactured by JASCO Corporation. The results are shown in Table 1.

<Lightness>
The lightness (L value) was measured using a spectrocolorimeter X-rite SP60 manufactured by X-Rite. The results are shown in Table 1.
Table 1 also shows the appearance color of the glass top plate for a heating cooker.

<Concealment of internal components of electromagnetic cooker>
The concealability of the internal components of the electromagnetic cooker was evaluated by visually determining whether the internal components permeate from the upper part of the plate (cooking surface) in the electromagnetic cooker provided with the glass top plate for the heating cooker. When the internal part was sufficiently concealed, it was judged as pass (evaluation ○), and when the internal part was clearly transparent and could be confirmed, it was judged as fail (evaluation x).

  As can be seen from Table 1, the glass top plate for a heating cooker obtained in Examples 1 to 5 has a transmittance of 50% or less, an L value of 75 or more, and the color of the pearl tone layer is reflected. It can be seen that it is possible to provide a glass top plate that exhibits a white color tone and can sufficiently conceal internal components.

(Experimental example 2)
In this example, an impact test and a thermal shock test are performed on the glass top plate for a heating cooker obtained in Examples 1 to 5 above, and the glass top plate for a heating cooker has a necessary strength. Evaluated whether or not.

<Impact test>
The impact test was performed assuming that a pan or the like dropped on the plate when the glass top plate for a heating cooker was actually used.
About each glass top plate for cooking-by-heating machines, the board of the magnitude | size of 40 cm x 50 cm square was prepared, and 4 corners were supported and fixed by the 2 cm chip | tip.
And the test which drops 500g of hard balls with respect to the said plate was done. The drop height started from 50 mm and increased every 400 mm to 400 mm. If it passes 400 mm, the strength is practically acceptable.
The results are shown in Table 2. In Table 2, when it passed 400 mm, it displayed as (circle).

<Thermal shock test>
The thermal shock test was conducted assuming that when the glass top plate for a heating cooker is actually used, the plate may be heated to close to 600 ° C., so that water is spilled on the heated top plate. .
About each glass top plate for heating cookers, the plate cut out to 10 square cm was prepared.
And the test which heats the said plate with a furnace so that it may become 620 degreeC, and drops this in 20 degreeC water was repeated 5 times.
The results are shown in Table 3. In Table 3, it can be said that when there is no crack in the substrate (evaluation ◯) and when the pearly layer is not peeled off from the substrate (evaluation ◯), the substrate has a strength with no practical problem.

  As can be seen from Table 2 and Table 3, it can be seen that any of the glass top plates for a heating cooker obtained in Examples 1 to 5 has a strength with no practical problem.

  Thus, according to this invention, it turns out that it can provide the glass top plate for heating cookers which has sufficient hiding power, and expresses sufficient pearl tone effect.

Explanatory drawing which shows the glass top plate for heating cookers in Example 1. FIG. Explanatory drawing which shows the glass top plate for heating cookers in Example 2. FIG. Explanatory drawing which shows the glass top plate for heating cookers in Example 3. FIG. Explanatory drawing which shows the glass top plate for heating cookers in Example 4. FIG. Explanatory drawing which shows the glass top plate for heating cookers in Example 5. FIG.

Explanation of symbols

1 Glass top plate for cooking device 2 Substrate 21 Cooking surface 22 Back side 3 Pearl tone

Claims (6)

It consists of a substrate made of translucent low expansion glass ceramics and a pearl tone layer laminated on the back side that is the opposite side of the cooking surface of the substrate,
The glass top plate has a light transmittance of 50% or less in a wavelength range of 760 to 830 nm.   2. The pearl tone layer according to claim 1, wherein the content of the pearl tone material is more than 10% by mass and 30% by mass or less, the silicone resin or siliceous sol is 10 to 30% by mass, and the organic binder is 40% by mass to 80% by mass. A glass top plate for a heating cooker, wherein a pearl color paint having a weight of less than% by mass is fired with a picture on the substrate.   The glass top plate for a heating cooker according to claim 1 or 2, wherein a coating layer formed by applying a dilute solution of an organometallic compound and baking it is laminated on the pearl tone layer.   The protective layer formed by applying and baking a heat-resistant resin or a heat-resistant resin and an inorganic pigment on the pearl tone layer or on the coating layer according to any one of claims 1 to 3. A glass top plate for a heating cooker, characterized in that:   5. The carbon electrode formed by applying and baking a conductive carbon paste on the pearly tone layer, the coating layer, or the protective layer according to claim 1. A glass top plate for a heating cooker, characterized in that:   The cooking according to any one of claims 1 to 5, wherein a decorative layer made of a glass composition or a glass composition and an inorganic pigment is laminated on a part or the whole of the cooking surface of the substrate. Glass top plate for dexterity.

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