JPH08131337A - Electromagnetically heating cooking receptacle and tableware - Google Patents

Abstract

PURPOSE: To provide an electromagnetically heating cooking receptacle and tableware which are hardly cracked, whose mechanical flexural strength is high, whose thermal shock resistance is improved and whose thermal efficiency is good and in which peeling between layers is hardly generated by combining a receptacle main body with laminated layers. CONSTITUTION: An electromagnetically heating cooking receptacle and tableware comprises a receptacle main body 1 made of a non-magnetic material, a ceramic layer or the mixed layer 2 of ceramic and metal materials provided on the inner surface of the receptacle main body 1, an inner coat layer 3 provided on the surface of the ceramic layer 2, a low expansive glaze layer 4 provided outside the receptacle main body 1, an induction heating part 5 provided on the surface of the glaze layer 4 and an outer coat layer 6 provided on the surface of the induction heating layer 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooking container for electromagnetic heating, the container body of which is made of a non-magnetic material, and a cooking device and tableware which can be used for oven cooking and open flame cooking. More specifically, it relates to a cooking container and tableware for electromagnetic heating using petalite and cordierite as raw materials for ceramics.

[0002]

2. Description of the Related Art Conventionally, some electromagnetic cookers have a heating system in which an eddy current is generated in a cooking container by a magnetic field generated from a heating coil to generate heat. As the electromagnetic cooker, a metallic one such as iron or stainless steel, which normally generates an eddy current, is often used.

However, recently, there has been an increasing demand to use a heat-resistant glass container or a ceramic container as a cooking container. Therefore, there is provided a cooking container made of these non-magnetic materials that can be used in an electromagnetic cooker. In this conventional type, as shown in FIG. 3, the cooking container 21 includes a non-metallic container body 22 and a heating layer 23 including a conductive layer 23a and a protective coating layer 23b on the outer bottom surface or the inner bottom surface thereof. Then, the conductive layer 23a is caused to self-heat to heat the object to be heated therein.

[0004]

However, when the above-mentioned conventional metal-coated cooking container is used, since the container body 22 is non-metallic, the heat transfer is 1/100 of that of metal.
And small. Furthermore, in induction heating, the temperature of the surface of the heat-generating part rises more rapidly than that of an open flame, and it is necessary to withstand this temperature change and temperature. However, the resistance to breakage when subjected to thermal shock is called thermal shock resistance. Ceramics, especially porcelain, has a small thermal shock resistance and, when subjected to a sudden temperature change, becomes fragments or cracks.

Generally, in a ceramic body, the thermal shock resistance can be controlled by the thermal expansion coefficient. Therefore, when the thermal expansion coefficient is close to 0, the thermal shock resistance becomes maximum. Further, even with the same composition, the thermal shock resistance of the porous base material is higher than that of the dense base material, while the porous base material has a higher water absorption. If the water absorbency is large, the water containing salt and the like impairs the adhesive force between the metal and the ceramic base that penetrates the base and is coated during actual use, leading to a peeling phenomenon.

Ceramics usually have a mechanical bending strength of 250.
It has a property that it is small at about 600 kg / cm ² and easily cracked. The present invention has been made in view of the above problems,
An object of the present invention is to provide a cooking container and tableware for electromagnetic heating, which has improved thermal shock resistance, is less likely to cause delamination, has a large mechanical bending strength and is resistant to cracking.

[0007]

In order to solve the above problems, an electromagnetic heating cooking container and tableware of the present invention include a container body made of a non-magnetic material, and a ceramic layer or an inner surface of the container body. A mixed layer of ceramic and metal, an inner surface coating layer provided on the surface of the ceramic layer, a glaze layer of low expansion glaze provided on the outside of the container body, and an induction heat generation provided on the surface of the glaze layer. And the outer surface coating layer provided on the surface of the induction heating portion. This makes it possible to increase the mechanical bending strength of the electromagnetic heating cooking container and prevent it from cracking, to improve the thermal shock resistance, to prevent delamination, and to increase the mechanical bending strength.

Further, in the above-mentioned structure of the cooking container for electromagnetic heating, a ceramic layer or a mixed layer of ceramic and metal is added in an amount of 5 to 5.
It is preferable that the thickness of the glaze layer is 100 μm and the thickness of the glaze layer is 50 to 150 μm.

In the above structure, it is preferable that the induction heating portion has a layer thickness of nickel 250 to 400 μm or copper 30 to 250 μm. Further, in the above-mentioned structure, when a petalite-based ceramic is used as a container body, the container body is a molded ceramic body composed of 30 to 70 parts by weight of petalite and 70 to 30 parts by weight of clay, cordierite and alumina. It is preferable.

In the present invention, as the ceramics forming the container body, petalite, cordierite-based, eucryptite-based, sponge-based ceramics, and alumina are used. As the composition of these, 30 to 70 parts by weight of petalite and 70 to 30 parts by weight of clay, cordierite, alumina and the like are used, and petalite and cordierite are essential components. Further, in addition to these, 10 to 20 parts by weight of Zn or the like may be added. If the petalite is less than 30 parts by weight, the thermal shock resistance deteriorates, rapid heating cannot be performed, and delamination easily occurs. If the petalite exceeds 70 parts by weight,
Mechanical bending strength cannot be increased and molding is extremely difficult and not practical.

The ceramic layer does not cause cracking or peeling of the inner surface coating layer that protects the surface of the ceramic forming the container body due to heat shrinkage, and can be used as a mold release coating film (preventing sticking). It is provided to increase the adhesive strength and hardness of the coating film). Adhesive strength should be obtained without causing cracking or peeling due to heat shrinkage of the container body. There is a thermal spraying method as one of the methods, but in that case, the ceramics used are:
Alumina, titania, ceramic metal or the like is used, and the thickness is set to 5 to 100 μm. In addition to thermal spraying, a film may be formed by coating a heat-resistant organic material or a method such as ceramic coating. When sprayed, the thickness is 5
If it is less than μm, the inner surface coating layer is likely to peel off, and if it exceeds 100 μm, peeling between the container body and the ceramic sprayed layer is likely to occur. More preferably, it is 10 to 30 μm. When it is provided by painting, it is preferably 20 to 60 μm.

[0012] The thickness of the inner surface coating layer is changed depending on the use such as holding strength and preventing charring so that it can be used in cookware. Fluorine resin or silicone resin with a thickness of 10
It is provided at 70 μm. If the thickness is less than 10 μm, the thickness is insufficient, and the life is too short even when used as a cooker or tableware. Especially when it is provided by painting or baking, the thickness may be insufficient. If the thickness exceeds 70 μm, peeling easily occurs between the ceramic sprayed layer and the cost increases.

The glaze layer is a layer for buffering the heat change between the container body and the induction heating portion and for bonding the induction heating portion. It is provided in a thickness of 50 to 150 μm using a low expansion glaze. The induction heating section is for heating the container by causing heat to be generated by electromagnetic induction. As the metal used as the conductor, silver, copper, nickel, aluminum or an alloy thereof, a ferrite ferrite alloy of a magnetic material, or the like is used. The thickness of this layer is
Depending on the metal, the thickness is set to 10 to 700 μm for silver, copper, nickel, or an alloy thereof. For example, 10 for silver
~ 30μm, 40 ~ 150μm for copper, 2 for nickel
It is 50 to 400 μm, and ferrite is 300 to 700 μm. The induction heating portion is formed by thermal spraying, sticking, painting or the like.

The outer surface coating layer is a layer for protecting the induction heating portion,
The thickness of the ceramic is set to 30 to 150 μm. The layer is formed by thermal spraying, coating baking, or the like.

[0015]

The electromagnetic heating cooking container of the present invention comprises a container body made of a non-magnetic material, a ceramic layer or a mixed layer of ceramic and metal provided on the inner surface of the container body, and a ceramic layer provided on the surface of the ceramic layer. Inner coating layer, a glaze layer of low expansion glaze provided on the outside of the container body, an induction heating section provided on the surface of the glaze layer, and an external coating provided on the surface of the induction heating section. Since it consists of layers, the cooking container for electromagnetic heating is placed on the electromagnetic coil, and when the electricity is turned on, the induction heating section generates heat by electromagnetic induction, which can quickly heat the food in the container body and weaken the heating power. It can also be used as tableware that can be kept warm. Moreover, the electromagnetic heating cooking container and tableware have high mechanical bending strength and are hard to break,
Good thermal shock resistance and less likely to cause delamination.

In the above structure, the ceramic layer or the mixed layer of ceramic and metal is 5 to 100 μm, and the glaze layer is 50 to 150 μm. Therefore, the inner surface coating layer and the container body, and the induction heating portion and the container body are bonded to each other. The strength can be increased, the difference in thermal expansion can be buffered, and delamination can be prevented.

Further, in the above structure, the induction heating portion has a layer thickness of nickel 250 to 400 μm or copper 30 to 250 μm, so that the heat generation efficiency is improved and the food can be quickly heated without causing uneven heating. .

In addition, in the above structure, when petalite-based ceramic is used as the container body, the petalite content is 30 to 30%.
70 parts by weight, clay, cordierite, alumina 70
A container body of a ceramics molded and molded from about 30 parts by weight of a raw material has a large mechanical bending strength, is resistant to cracking, improves thermal shock resistance, and is resistant to delamination.
The mechanical bending strength can be increased.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) and 1 (b) are sectional views showing a cooking container for electromagnetic heating according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a container body, a ceramic layer 2 is provided on the inner surface of the container body 1 by thermal spraying, and an inner surface coating layer 3 is provided on the surface of the ceramic layer 2. Further, a glaze layer 4 of low expansion glaze is provided on the outer surface of the container body 1, an induction heating portion 5 is provided on the surface of the glaze layer 4, and an external surface of ceramic or other heat-resistant material is provided on the surface of the induction heating portion 5. A coating layer 6 is provided and configured.

The container body 1 is formed from a raw material consisting of 50 parts by weight of petalite having the composition shown in Table 1 and 50 parts by weight of clay having the composition shown in Table 2 to have a thickness of 5 to 8 mm by, for example, slurry casting or press molding. ing.

[0021]

[Table 1]

[0022]

[Table 2]

The ceramic layer 2 is formed by a method such as coating baking of a heat-resistant, high-hardness material such as alumina or titanium oxide.
Approximately 50 μm is provided. It is preferable that the thermal expansion coefficient of the container body 1 is substantially the same as that of the container body 1, and alumina having good adhesion is sprayed. Before providing the ceramic layer 2, the surface of the container body 1 is sandblasted.

A glaze layer may be formed between the ceramic layer 2 and the container body 1 in order to buffer the difference in adhesiveness and thermal expansion coefficient between them. This makes it possible to increase the adhesive strength between the ceramic layer and the container body, buffer the difference in thermal expansion, and prevent delamination.

The inner surface coating layer 3 is a layer for preventing scorching of the container body 1, that is, the ceramic layer 2, and is provided with a fluororesin or a silicone resin in a thickness of 10 to 70 μm. The fluororesin here means tetrafluoroethylene resin (PT
FE), a fluororesin such as tetrafluoroethylene-hexafluoroethylene copolymer resin (FEP), and tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (PFA), and a coating film containing these.

The glaze layer 4 is a layer for buffering the heat change of the container body 1 and the induction heating portion 5 and for adhering the induction heating portion 5 and is provided in a thickness of 50 to 150 μm. As the glaze, a low expansion glaze such as petalite glaze (mainly petalite) is used. The reason is that if the difference in thermal expansion coefficient between the glaze layer 4 and the container body 1 is large, that is, if the thermal expansion coefficient of the glaze layer 4 is large, the glaze layer 4 peels off and the induction heating portion 5 peels off. This is because there is a risk.

The induction heating portion 5 is sprayed on the surface of the glaze layer 4,
It is provided by a method such as paint baking and transfer. The thickness is 10 to 30 μm when spraying silver, 40 to 150 μm when spraying copper, 200 to 350 μm when spraying a mixed metal of nickel-aluminum, and when spraying a ferrite alloy. Is set to about 400 to 850 μm. The forming method may be a method of spraying a metal or alloy wire or powder, or a method of forming by a film forming method.

The outer surface coating layer 6 is heat-resistant so that it can withstand the high temperature of the induction heating portion 5, has substantially the same coefficient of thermal expansion and has good adhesiveness, and has a relatively small coefficient of thermal expansion such as ceramic paint. Baking is preferred.

(Embodiment 1) A first embodiment of the method for manufacturing a cooking container for electromagnetic heating according to the present invention will be described below. First, Table 1
50 parts by weight of petalite having a composition as shown in FIG. 2 and 50 parts by weight of clay having a composition as shown in Table 2 are mixed to form a slurry, and the slurry is cast into a cooking device as shown in FIG. The thickness of the bottom of the container body 1 was molded to about 8 mm. Next, it was unglazed at 700 to 800 ° C. and then main baked at 1180 ° C. while correcting the deformation of the equipment.

Next, the glaze layer 4 was coated on the outside of the container body 1 with a petalite-based low expansion coefficient glaze and baked at 1180 ° C. to provide about 100 μm. The induction heating part 5 was provided with a thickness of about 100 μm by plasma-spraying copper on the surface of the glaze layer 4.

Next, a ceramic-based coating (Asahi Chemical Industry Co., Ltd.) is used to prevent oxidation and damage of the induction heating section 5.
Sumiceram P-190) was applied, dried and fired to form a seal / protective coating film having a thickness of about 50 μm.

Next, as shown in FIG. 1B, alumina powder (K-16 manufactured by Showa Denko KK) was applied to the inner surface of the container body 1.
T) is sprayed by plasma spraying to a thickness of about 20 μm to form the ceramic layer 2. Before providing the ceramic layer 2, the surface of the container body 1 is sandblasted to roughen the surface and improve the adhesion between the container body 1 and the ceramic layer 2.

Next, the inner surface coating layer 3 is applied to the inner surface of the ceramic layer 2 by a fluororesin primer coating (Daikin Industry Co., Ltd.).
EK1909BKN manufactured by Daikin Industries, Ltd., and dried, and then fluorinated resin enamel paint (DK4609B manufactured by Daikin Industries, Ltd.)
K) was painted. By baking this at 380 ° C., an inner surface coating layer having a thickness of about 30 μm was provided. When the fried egg was cooked using the thus prepared cooking container, the fried egg was normally heated, heated, and had good peelability.

(Example 2) In producing the container main body 1, petalite was added to each of 20, 30, and 4 by mixing the raw materials.
0, 60, 70, 80 parts by weight, 80, 70, 60, 40, 3 of clay, koudierite, alumina, etc., respectively.
About 0 and 20 parts by weight, molding was performed in the same manner as in the above-mentioned example to prepare a cooking device, and tests such as thermal shock resistance, water absorption measurement, and thermal deformation were performed. As a result, petalite is 30 ~
70 parts by weight of clay, 70 cordierite and 70 alumina
It was found that the cooker consisting of a container body molded from 30 to 30 parts by weight of a ceramic raw material has the smallest water absorption amount and is not damaged by thermal shock of quenching from 500 ° C. to room temperature, which is suitable for this application. .

(Example 3) In producing the container body 1, in order to determine the firing temperature for the purpose of reducing the water absorption of the container body, the firing temperature was set to 800 ° C, 900 ° C, and 1 ° C, respectively.
000 ° C, 1050 ° C, 1100 ° C, 1150 ° C, 11
80 ° C, 1200 ° C, 1230 ° C, 1250 ° C, 127
It was baked at 0 ° C. and the water absorption was measured. As a result, 1180
It had the smallest water absorption at ˜1250 ° C. and was optimum.

Example 4 In order to investigate the relationship between the adhesiveness between the induction heating portion 5 and the glaze layer 4 or the adhesiveness between the ceramic layer 2 and the glaze layer 4 and the thickness of the glaze layer 4, as shown in FIG. To
A glaze layer 4 was provided between the container body 1 and the ceramic layer 2. The thickness of each of these glaze layers 4 is 0 μm, 50 μm, 1
It was manufactured by changing the thickness to 00 μm, 150 μm and 200 μm.
As a result, the adhesion of the glaze layer to the induction heating part 5 is 50 to 50%.
It adhered well at 150 μm, and when it exceeded 150 μm, destructive peeling of equipment occurred during heating. The adhesion between the container body 1 and the ceramic layer 2 was 0 to 200 μm or less, and no peeling occurred during heating.

[0037]

As described above, according to the present invention, there is little water absorption, high thermal shock resistance, delamination is unlikely to occur, mechanical bending strength is high, cracking is difficult, and electromagnetic heating is possible for rapid cooking. The tableware can be used as a cooking container and can be kept warm.

[Brief description of drawings]

1 is a sectional view showing a cooking container (tableware) for electromagnetic heating according to an embodiment of the present invention, (a) is an overall sectional view, and (b) is an enlarged sectional view of a portion A in (a). is there.

FIG. 2 is a sectional view showing another example of the present invention.

3A and 3B are sectional views illustrating a conventional example, FIG. 3A is an overall sectional view, and FIG. 3B is an enlarged sectional view of a portion B in FIG.

[Explanation of symbols]

 1 Container body 2 Ceramic layer 3 Inner surface coating layer 4 Glaze layer 5 Induction heating part 6 Cover coat layer

Claims (4)

[Claims] 1. A container body made of a non-magnetic material, a ceramic layer or a mixed layer of ceramic and metal provided on the inner surface of the container body, an inner surface coating layer provided on the surface of the ceramic layer, and Cooking for electromagnetic heating comprising a glaze layer of low expansion glaze provided on the outside of the container body, an induction heating part provided on the surface of the glaze layer, and an outer surface coating layer provided on the surface of the induction heating part Containers and tableware. 2. The ceramic layer or a mixed layer of ceramic and metal is 5 to 100 μm, and the glaze layer is 50 to 150.
The cooking container and tableware for electromagnetic heating according to claim 1, wherein the cooking container and the tableware have a size of μm. 3. The induction heating part is made of nickel 250 to 400 μm.
m or a layer thickness of copper of 30 to 250 μm, the cooking container and tableware for electromagnetic heating according to claim 1 or 2. 4. When a petalite-based ceramic is used as a container body, it is a molded ceramic container body composed of 30 to 70 parts by weight of petalite and 70 to 30 parts by weight of clay, cordierite and alumina. Claim 1,
2. A cooking container and tableware for electromagnetic heating according to either 2 or 3.