JP2014092323A - Glass top plate for cooking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass top plate for a cooking device which improves visibility of a display furthermore.SOLUTION: A glass top plate 1 for a cooking device has a light shielding part 11 and a translucent display part 12 provided on a substrate glass 2, and is used in a state where a display is arranged below the display part 12. The light shielding part 11 is disposed by laminating at least a light shielding layer 3 on a back side surface 22 of the substrate glass 2 and the display part 12 is disposed by laminating only a transparent resin layer 4 on a back side surface 22 of the substrate glass 2. A refractive index ρof the transparent resin layer 3, with respect to a refractive index ρof the substrate glass 2, has a relation: |ρ-ρ|≤0.1. An arithmetic average roughness Ra of an exposed surface of the transparent resin layer 4 is 0.09 μm or less. The transparent resin layer preferably has a color difference ΔE before and after being retained at 170°C for 5 hours, of 1.5 or less.

Description

  The present invention relates to a glass top plate for a cooker provided with a display unit.

  Conventionally, a glass top plate for a cooker made of a glass plate is installed on the top of a cooker such as an electromagnetic cooker or a gas cooker. A heated object such as a pan is placed on the glass top plate for a cooker, and the heated object is heated by an induction heating coil that performs induction heating inside the cooker, or a heating device such as an electric heater or a halogen heater. Heated. In particular, electromagnetic cookers tend to be increasingly demanded in recent years because of their high safety, and accordingly, the demand for glass top plates for cookers is also increasing.

  The glass top plate for a cooker is generally configured by providing a transparent substrate glass with a light-shielding portion and a translucent display portion. The light shielding part is configured by laminating at least a light shielding layer that prevents light transmission on the back side surface of the substrate glass. The color may be further laminated with a decorative layer for applying a pattern.

  The said display part is arrange | positioned facing the display body arrange | positioned under the glass top plate for cookers, and is for seeing through the display of a display body. Therefore, the display portion is provided in a state having translucency. Moreover, low expansion | swelling crystallized glass is used as substrate glass of the said glass top plate for cookers.

  By the way, when the surface roughness of the substrate glass is relatively rough, when the substrate glass is used as it is for the display unit, the display of the display body that can be seen through the display unit is blurred, causing a problem in visibility. There is a case. Therefore, Patent Document 1 proposes that a translucent plate is bonded to the back side surface of the substrate glass via a transparent intermediate layer, and the exposed surface of the translucent plate is made smooth.

JP 2008-2676335 A

  However, although the configuration described in Patent Document 1 improves the visibility of the display unit as compared to the conventional art, an interference fringe pattern called moire occurs particularly when the display on a recent high-precision liquid crystal display device is seen through. Visibility may be reduced.

  This invention is made | formed in view of this background, Comprising: It aims at providing the glass top plate for cookers which further improved the visibility of a display.

One aspect of the present invention is a glass top plate for a cooker that is provided with a light-shielding portion and a translucent display portion on a substrate glass, and is used in a state in which a display body is disposed below the display portion,
The light shielding part is provided by laminating at least a light shielding layer on the back side surface of the substrate glass,
The display unit is provided by laminating only a transparent resin layer on the back side of the substrate glass,
The refractive index ρ ₁ of the transparent resin layer has a relationship of | ρ ₀ −ρ ₁ | ≦ 0.1 with respect to the refractive index ρ _{0 of the} substrate glass.
The arithmetic average roughness Ra of the exposed surface of the transparent resin layer is 0.09 μm or less, and the glass top plate for a cooker is characterized in that (Claim 1).

  The glass top plate for a cooker of the present invention has the display unit provided by laminating only the specific transparent resin layer. Therefore, the visibility when viewing the display of the display body through the display unit can be improved as compared with the conventional case. That is, the transparent resin layer has a refractive index and an arithmetic average roughness of the exposed surface within the specific ranges. By having all these requirements, the transparent resin layer can wipe away the influence of the surface roughness of the substrate glass and realize excellent visibility.

Explanatory drawing which shows the structure of the glass top plate for cookers in Example 1. FIG. Explanatory drawing which shows the observation result of each Example and a comparative example in the moire observation tests 1 and 2. FIG.

The refractive index ρ ₁ of the transparent resin layer has a relationship of | ρ ₀ −ρ ₁ | ≦ 0.1 (within a range of ρ ₀ ± 0.1) with respect to the refractive index ρ _{0 of the} substrate glass. And the arithmetic mean roughness Ra of the exposed surface of the said transparent resin layer is 0.09 micrometer or less. By having both of these characteristics, it is possible to reliably prevent the occurrence of moire and to ensure excellent visibility of the display unit.

When the refractive index ρ ₁ of the transparent resin layer is out of the above range, the difference from the refractive index ρ _{0 of the} glass becomes large, which may be one of the factors that cause moire. Therefore, the refractive index ρ ₁ of the transparent resin layer needs to be limited within the above range, and preferably, the refractive index ρ ₁ is further limited to satisfy a relationship of | ρ ₀ −ρ ₁ | ≦ 0.05 (ρ ₀ ± 0.05).

  Further, when the arithmetic average roughness Ra of the exposed surface of the transparent resin layer exceeds 0.09 μm, it is difficult to sufficiently suppress the occurrence of moire. Therefore, the arithmetic average roughness Ra of the exposed surface of the transparent resin layer needs to be limited to 0.09 μm or less, preferably 0.04 or less.

  The transparent resin layer of the glass top plate for a cooking device preferably has a color difference ΔE before and after being held at 170 ° C. for 5 hours of 1.5 or less (Claim 2). Thereby, even when used in a relatively high temperature environment such as a glass top plate for a cooker, the color change is small, and the visibility can be further improved on the color tone surface. The color difference ΔE is further preferably limited to 1.0 or less. The color difference ΔE can be obtained by Expression (1) shown in an experimental example described later.

As the synthetic resin constituting the transparent resin layer, various synthetic resins having the refractive index ρ ₁ can be employed. Among these, it is preferable that the said transparent resin layer consists of an epoxy resin (Claim 3). The epoxy resin has the above two characteristics, is easy to form a layer, and easily secures the arithmetic average roughness Ra of the exposed surface. The formation of the transparent resin layer using an epoxy resin can be performed by, for example, applying it to a substrate glass by a bar coating method, a screen printing method, a potting method, or the like, followed by thermosetting.

  Moreover, it is preferable that the thickness of the said transparent resin layer is 5 micrometers or more (Claim 4). Thereby, even when the roughness of the back side surface of the said substrate glass is large, the influence can be wiped off reliably. The thickness of the transparent resin layer is more preferably 20 μm or more because stable coating can be performed. On the other hand, since application | coating operation will become complicated when thickness is too thick, it is good to set it as 50 micrometers or less preferably.

  The substrate glass preferably has an arithmetic average roughness Ra of 0.08 to 0.15 μm on the front side surface (Claim 5). Thereby, the visibility of the said display part can be ensured reliably. When the arithmetic average roughness Ra of the front side surface of the substrate glass exceeds 0.15 μm, the visibility in the display unit may be lowered. In addition, it is difficult on manufacture that arithmetic mean roughness Ra of the surface side of the said board | substrate glass is less than 0.08 micrometer, and the significant increase in cost is anticipated. Therefore, the arithmetic average roughness Ra of the front side surface of the substrate glass is preferably in the above range.

  The substrate glass may have an arithmetic average roughness Ra of the back side surface of 0.4 to 0.7 μm. The problem of the roughness of the back side surface of the substrate glass can be eliminated by the presence of the transparent resin layer as described above. Therefore, when the roughness of the back side surface of the substrate glass is relatively rough, for example, there is no problem even if the arithmetic average roughness Ra is 0.4 to 0.7 μm. Therefore, a roll-out method or the like that can be finished only in a relatively rough state can be adopted as a method for manufacturing the substrate glass, and the degree of freedom in manufacturing the substrate glass can be increased. Moreover, the process of adjusting the surface roughness of the back side surface of the substrate glass can be omitted, which is effective for cost reduction.

  The roll-out method, which is a method for producing the substrate glass, is a method of forming a plate by passing a raw material between two cooling rollers, and is obtained by using a roller having a desired surface property. It is possible to control the surface properties of the plate.

  Further, the substrate glass is preferably made of low expansion crystallized glass whose main crystal is β-quartz solid solution or β-spodumene (Claim 7). By adopting such crystallized glass, even if a large thermal stress is generated in the top plate surface due to a temperature difference during cooking, it is not damaged.

  As a specific low expansion crystallized glass applicable as the substrate glass, for example, Neoceram N-0 manufactured by Nippon Electric Glass Co., Ltd. can be adopted. This type of glass is excellent in heat resistance and has a small shape change accompanying a temperature change, and is suitable as a substrate glass for a glass top plate for a cooker. In this case, it is possible to improve the visibility of the display unit without increasing the manufacturing cost by allowing the arithmetic average roughness Ra of the back side surface to be 0.4 to 0.7 μm as described above.

  The substrate glass may be colorless or colored, but preferably transmits visible light well (for example, the average transmittance of visible light having a wavelength of 400 to 800 nm is 15% or more). .

  The display body may be a liquid crystal display device. In recent years, liquid crystal display devices are capable of displaying images with very high pixels, and the visibility of a display portion that is transmitted has a great influence on the maintenance of the clarity. Therefore, in the case where a high-pixel liquid crystal display device is employed as the display body, it is very effective to apply the glass top plate for a cooker having the display unit with excellent visibility.

  Moreover, the light shielding part provided in the said substrate glass can be provided by laminating | stacking a light shielding layer on the back side surface of the said substrate glass at least. Various known layers can be applied as the light shielding layer. Specifically, for example, a layer composed of a raster color, a layer composed of a glass composition and an inorganic pigment, a layer composed of a pearl tone material and a silicone resin or siliceous sol, and the like can be mentioned. The light shielding layer may be formed by laminating the above-described layers alone on the back side surface or by laminating a plurality of layers.

Example 1
The Example of the said glass top plate for cookers is demonstrated using FIG.
As shown in FIG. 1, the glass top plate 1 for a cooking device according to the present example includes a substrate glass 2 provided with a light-shielding portion 11 and a translucent display portion 12, and a display body 9 is disposed below the display portion 12. It is the glass top plate for cookers used in the state which carried out.

  The light shielding portion 11 is provided by laminating at least the light shielding layer 3 on the back side surface 22 of the substrate glass 2. The display unit 12 is provided by laminating only the transparent resin layer 4 on the back side surface 22 of the substrate glass 2.

When the glass top plate 1 for a cooker of this example is actually used for a cooker, a heating device such as an induction heating coil, an electric heater, or a halogen heater is provided below the light shielding portion 11. A device light emitting unit is provided below the display unit 12.
This will be described in detail below.

First, Neoceram N-0 was prepared as the substrate glass 2. The substrate glass 2 has a cooking surface (front side surface) 21 made of a smooth surface having an arithmetic average roughness Ra of 0.08 μm, and a rough surface having an arithmetic average roughness Ra of 0.70 μm on the opposite side of the cooking surface 21. And a rear side surface 22 made of a conversion surface. The refractive index ρ ₀ of the substrate glass 2 is 1.54. In addition, the low expansion crystallized glass used for the glass top plate for a cooker generally has a refractive index ρ ₀ of 1.54 to 1.55 and an arithmetic average roughness Ra of the front side surface of 0.08 to _0. The arithmetic average roughness Ra of the back side is 0.40 to 0.70 μm.

  Next, as a paste for the light-shielding layer 3, a pearl-colored paint composed of a pearl-colored material, a silicone resin, and an organic vehicle for screen printing, and a black raster-painting material were prepared.

  In addition, an epoxy resin A was prepared as a resin for the transparent resin layer 4. Epoxy resin A is a mixture of 50% EPOXY RESIN XNR6830 (Nagase Elex), 49.5% HARDENER XNH6830 (M) (Nagase Elex), 0.5% Sylface SAG008 (Nisshin Chemical Industries).

Next, a manufacturing method will be described.
First, the pearl color paint was applied to a part of the back side surface 22 of the glass substrate 2 (a part other than the part serving as the display unit 12) using a stainless 180 mesh screen, and baked at 750 ° C. . Thereby, a pearl tone layer 31 having a film thickness of 15 μm was formed.

  Next, the black raster painting material was applied onto the pearl tone layer 31 using a stainless steel 350 mesh screen, and baked at 750 ° C. Thereby, the light shielding layer 3 was formed.

  Next, the epoxy resin A for the transparent resin layer 4 was applied to the portion to be the display unit 12. The coated epoxy resin A was spread using a bar coater (No. 579 bar coater ROD No. 14 manufactured by Yasuda Seiki Seisakusho Co., Ltd.), then heated and cured at 140 ° C. for 2 hours, and a transparent resin layer having a thickness of 25 μm. 4 was formed.

The light-shielding portion 11 provided with the light-shielding layer 3 has a pearly silver gray expression that varies depending on the viewing angle.
As shown in FIG. 1, the transparent resin layer 4 is formed so as to cover a part of the light shielding layer 3, but hardly affects the expression of the light shielding portion 11.
Further, in this example, the light shielding layer 3 composed of two layers of the pearl tone layer and the raster layer is formed on the entire surface other than the display unit 12, but various known layers can be applied to the light shielding layer, A portion that is not formed may be provided.

(Example 2)
In this example, the resin for the transparent resin layer 4 used in the display unit 12 of Example 1 is changed to the epoxy resin B. Epoxy resin B is a mixture of 99.5% Photobond 350H (Sunrise MSI) and 0.5% Silface SAG008 (Nissin Chemical Industry). Others are the same as in the first embodiment.

(Example 3)
In this example, the resin for the transparent resin layer 4 used in the display unit 12 of Example 1 is changed to the epoxy resin C and cured by a UV irradiator. Epoxy resin C is a mixture of 99.5% Photobond 200 (Sunrise MSI) and 0.5% Silface SAG008 (Nisshin Chemical Industry). The curing process was performed using a 365 nm LED as a UV irradiator and irradiating 600 mW / cm ² for 5 seconds. Others are the same as in the first embodiment.

(Comparative Example 1)
In this comparative example, the resin for the transparent resin layer 4 used in the display unit 12 of Example 1 is changed to the silicone resin D. Silicone resin D is a mixture of KR300 (Shin-Etsu Chemical) 70.0% and butyl cellosolve 30.0%. The transparent resin layer 4 was formed by applying a silicone resin D on the display portion using a stainless steel 250 mesh screen and baking it at 200 ° C.

(Comparative Example 2)
In this comparative example, the display unit 12 is constituted only by the substrate glass 2 and the transparent resin layer 4 is not formed. That is, the surface exposed on the back side of the display unit 12 is the back side surface 22 itself of the substrate glass 2.

(Experimental example)
First, Table 1 shows the results of measuring various physical properties of the transparent resin layer 4 in Examples 1 to 3 and Comparative Example 1. The measuring method of each characteristic is as follows.

<Refractive index ρ ₁ >
The refractive index ρ _{1 of the} resin was measured using a multi-wavelength refractometer DR-M2 manufactured by Atago Co., Ltd. according to JIS K7142.

<Arithmetic mean roughness Ra>
Arithmetic average roughness Ra was measured using Surfcom 130A manufactured by Tokyo Seimitsu Co., Ltd. in accordance with JIS B0601.

<Color difference ΔE>
The color difference ΔE was obtained by the following equation (1).
ΔE = √ (L ₁ −L ₀ ) ² + (a ₁ −a ₀ ) ² + (b ₁ −b ₀ ) ² Formula (1)
Here, each variable is a value measured by a spectrocolorimeter (spectral colorimeter x-riteSP60 manufactured by x-rite), and L ₀ , a ₀ , and b ₀ are all room temperature (25 C 1), and L ₁ , a ₁ , and b ₁ are values measured by heating to 170 ° C. and holding for 5 hours, and then cooling to room temperature.

  Next, Table 1 shows the results of two types of moire observation tests for confirming visibility. The conditions of each test are as follows.

<Moire observation test 1>
In the moiré observation test 1, a display body (not shown) is arranged below the display portion (position 3.5 mm below the back side surface 22 of the substrate glass 2) in the glass top plate for a cooker of each example and comparative example, Judgment was made by visual observation from above the display unit 12. A liquid crystal display device having a screen size of 8.1 inches and 15000 pixels was used as the display body. Good when moiré is hardly observed and is clearly observable (○), when slightly moire is observed and slightly lacking in sharpness, conventional standard (△), moiré rate is high and sharpness is clearly reduced The case was judged as defective (x).

<Moire observation test 2>
The moire observation test 2 was performed under the same conditions as those of the moire observation test 1 except that the liquid crystal display device was changed to a high pixel having 17 inches of 1300000 pixels. The judgment criteria in this test were also the same as those in the moire observation test 1.

  The above two moire observation test results are also shown as an enlarged photograph in FIG.

  As can be seen from Table 1 and FIG. 2, in the case of Examples 1 to 3, the occurrence of moire was small and very good visibility was obtained. On the other hand, in the case of the comparative example 1, in the moire observation test 1, a slight moire was produced, but in the moire observation test 2, the sharpness was greatly reduced and it was judged as defective. Moreover, in the case of the comparative example 2 which does not provide the transparent resin layer 4, it was judged that it was defect in any test.

  In the above two moire observation tests, the influence of the color difference ΔE was not so much. In terms of quality as a glass top plate for a cooker, it is effective that the color change of the display unit 12 is small. From this point of view, Example 1 having a small color difference ΔE is most excellent.

DESCRIPTION OF SYMBOLS 1 Glass top plate for cookers 11 Light-shielding part 12 Display part 2 Substrate glass 21 Cooking surface 22 Back side surface 3 Light-shielding layer 4 Transparent resin layer

Claims (8)

A glass top plate for a cooking appliance comprising a substrate glass provided with a light shielding portion and a translucent display portion, and used in a state in which a display body is disposed below the display portion,
The light shielding part is provided by laminating at least a light shielding layer on the back side surface of the substrate glass,
The display unit is provided by laminating only a transparent resin layer on the back side of the substrate glass,
The refractive index ρ ₁ of the transparent resin layer has a relationship of | ρ ₀ −ρ ₁ | ≦ 0.1 with respect to the refractive index ρ _{0 of the} substrate glass.
An arithmetic average roughness Ra of the exposed surface of the transparent resin layer is 0.09 μm or less.   The glass top plate for cooking appliances according to claim 1, wherein the transparent resin layer has a color difference ΔE before and after being held at 170 ° C for 5 hours of 1.5 or less.   The glass top plate for cooking appliances according to claim 1 or 2, wherein the transparent resin layer is made of an epoxy resin.   The glass top plate for cooking appliances of any one of Claims 1-3 WHEREIN: The thickness of the said transparent resin layer is 5 micrometers or more, The glass top plate for cooking appliances characterized by the above-mentioned.   The glass top plate for cooking appliances according to any one of claims 1 to 4, wherein the substrate glass has an arithmetic average roughness Ra of 0.08 to 0.15 µm on the front side surface. Glass top plate.   The glass top plate for cooking appliances according to any one of claims 1 to 5, wherein the substrate glass has an arithmetic average roughness Ra of 0.4 to 0.7 µm on the back side surface. Glass top plate.   The glass top plate for cooking appliances of any one of Claims 1-6 WHEREIN: The said display body is a liquid crystal display device, The glass top plate for cooking appliances characterized by the above-mentioned.   The glass top plate for a cooker according to any one of claims 1 to 7, wherein the substrate glass is made of low expansion crystallized glass whose main crystal is β-quartz solid solution or β-spodumene. Glass top plate for cooker.