JPH0227687A - Nonmetallic container for heated cooking utensil and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the characteristic due to the vacant boiling and scorching by forming a thin metal film and a thin metal film protecting film on the bottom of a nonmetallic container mainly made of eucryptite or aluminum titanate. CONSTITUTION:A thin metal film 2 mainly made of silver and containing glass frit 20wt.% or below is formed on the outer face of the bottom of a nonmetallic container 1 mainly made of eucryptite or aluminum titanate or a mixture of them, a thin metal film protecting film 3 is formed on its outside. The heat- cooking nonmetallic container with a stable overcoat layer, which has the characteristic not impaired in the usage state such as vacant boiling and scorching and is not damaged when washed, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a non-metallic container for heating cookers such as ceramic pots used for cooking on gas stoves, electric stoves, induction heating cookers, etc., and a method for manufacturing the same. be.

BACKGROUND OF THE INVENTION Conventional earthenware pots used, for example, in induction heating cookers, are as shown in Japanese Utility Model Application Publication No. 145596/1983.
Betalite ceramics were used as the body of the earthenware pot, and a sprayed layer of aluminum was formed on the bottom surface using a thermal spraying method.

Problems to be Solved by the Invention However, with the above-mentioned conventional non-metallic container for cooking DG using an earthenware pot, the earthenware pot cannot be used in an induction heating cooker or in an empty cooking state without putting food inside the earthenware pot. When used on an electric stove, etc., the sprayed aluminum layer burns 30% of the heat per minute.
Since the temperature rises rapidly from 0 to 400''C, there is a problem in that the earthenware pot body suffers from a thermal shock resulting in cracking or other destruction.

Also, even if you put food in the earthenware pot and cook using an induction cooker or electric stove, if the mochi or udon gets burnt, the temperature of the sprayed aluminum layer will rise to 70"C. It rose nearby, causing melting of the aluminum and damage such as cracks to the earthenware pot body.
There was a problem that it became unusable.

On the other hand, some earthenware pots or glass containers use silver paste, which has a higher melting point than aluminum, as a heating element in order to prevent the above-mentioned melting. Compared to those that use a sprayed aluminum layer, the durability is improved, but the silver heating element may melt and the earthenware pot itself may break due to several burns.
There was a problem that it became unusable. Furthermore, since silver is a relatively soft metal, scratches occur when rubbed with a nylon scrubber or metal scrubber when cleaning after use, and as a result, there is a problem in that it promotes fusing and cracking of the clay pot body during use.

Furthermore, some earthenware pots have a glass overcoat to protect the silver layer, but even in these cases, repeated use can cause cracks in the overcoat, causing the overcoat to fall off or cracks to form on the silver layer or the earthenware pot itself. There was a problem in that the clay pot grew to such an extent that it led to the aforementioned melting and cracking of the earthenware pot body.

As described above, conventional non-metallic containers for cooking devices have various problems to be solved.

The present invention has been made to solve these problems, and has a stable overcoat layer that does not lose its properties even under usage conditions such as dry cooking and scorching, and does not cause scratches even when washed. The object of the present invention is to provide a non-metallic container for a heating cooker and a method for manufacturing the same.

Means for Solving the Problems In order to solve the above problems, the non-metallic container for a heating cooker of the present invention includes, on the bottom outer surface of the non-metallic container whose main component is eucryptite, aluminum titanate, or a mixture of both. Mainly composed of silver and glass frit 20
It is constructed by forming a thin metal coating containing less than or equal to the weight of the thin metal coating, and further forming a thin metal coating protective coating on the outside of the thin metal coating.

Further, the thin metal film protective film is composed of at least 30% by weight of glass, a ceramic filler, and an inorganic pigment, and the ceramic filler is composed of fine ceramic particles such as eucryptite, aluminum titanate, or a mixture of both, potassium titanate, α -Alumina,
It is formed using whiskers of one or more types of beryllia, boron carbide, silicon carbide, and silicon nitride, and one or more types of scale-like ceramics of one or more types of mica, alumina, and iron oxide.

Still another thin metal film protective film is formed by thermal spraying one or more of metals, ceramics, and glass; stainless steel is used as the metal, and alumina and silica are used as the ceramics.

It is formed using one or more of zirconia, zircon, cordierite, eucryptite, and aluminum titanate.

Function Betalite ceramics are generally composed of clay, mainly silica, and alumina, and have a coefficient of linear expansion of 0.
3 to 1.0 inches (room temperature to 1000 degrees Celsius) - In terms of numbers, it is a material that is resistant to thermal shock due to rapid heating and cooling, but in dry cooking where only the bottom of the earthen pot body is rapidly heated, Directly heated part (bottom part) and non-heated part (rising part, side wall part)
The thermal gradient becomes very large, and this difference in thermal expansion causes cracks to form, leading to failure.

In addition, when mochi or udon is burnt, the burnt layer becomes a heat insulating layer, and the burnt area is abnormally heated to near 7QO"Q, creating a very large thermal gradient with the surrounding area, and this difference in thermal expansion causes cracks. occurs, leading to destruction.

In order to solve these problems, the present invention uses a non-metallic container (porcelain) whose main component is eucryptite, aluminum titanate, or a mixture of both.

This eucryptite and aluminum titanate-based porcelain is manufactured using refined raw materials, and has a linear expansion coefficient of 0 to -0.6% (room temperature to 1000"C). It is very small compared to other types of ceramics.

Therefore, it can sufficiently withstand sudden differences in thermal expansion during dry cooking or scorched states, and as a result, no breakage such as cracking occurs. Incidentally, even if the non-metallic container of the present invention is glazed, it has the same effect and is superior in design.

In addition, in a scorched state, in a conventional thermally sprayed aluminum layer, the melting point of aluminum is relatively low at approximately 660"C, so fusing easily occurred, but the melting point is 960"C.
If a paste containing C as a main component is used, it will be difficult to melt and cut. However, since general silver paste contains 30 to 40% by weight of glass, it is necessary to bake at a temperature below the melting point of silver, and baking was performed using glass that has a working point around 800"C. In such a thin metal coating, the glass softened in the burnt state, and several burns caused blisters in the thin metal coating, and furthermore, a fusing phenomenon occurred.

In the present invention, by controlling the amount of this glass added to 20% by weight or less, preferably 10% by weight or less, the reaction with silver, which is the main component of the thin metal coating, is suppressed and the thin metal coating has the characteristics of silver. It is made flexible so that it can follow sudden differences in thermal expansion during dry cooking and burnt conditions, and also prevents blistering and melting during burnt conditions due to softening of the glass.

Thin metal coatings that use glass as a protective coating,
During use, cracks appeared, glass fell off, cracks penetrated into the thin metal coating and caused melting, and non-metallic containers cracked.

In the present invention, as this thin metal coating protective coating, a coating consisting of glass, ceramic filler, and inorganic pigment is formed, or metal or ceramic is used.

The above-mentioned problem is solved by thermally spraying one or more types of glass.

In a thin metal protective coating consisting of glass, ceramic filler, and inorganic pigment, glass acts as a binder, and if it is less than 30% by weight, sufficient strength cannot be maintained; It is necessary to include it.

Ceramic filler has the effect of increasing the strength of the thin metal protective coating and adjusting thermal expansion, preventing cracks from occurring during the manufacturing process and during cooking, and preventing scratches from nylon scrubbers or metal scrubbers during cleaning. It has the effect of preventing

The fine-grained ceramic in the ceramic filler uses low-expansion ceramics such as eucryptite, aluminum titanate, or a mixture of both, and mainly has the effect of adjusting the coefficient of thermal expansion and preventing the occurrence of cracks. Secondly, it has the effect of increasing strength and hardness.

The whiskers in ceramic and Fuchs fillers use one or more of potassium titanate, α-alumina, beryllia, boron carbide, silicon carbide, and silicon nitride, and these generally have high strength and excellent heat resistance, and are thin films. It has the effect of increasing the strength of the protective metal coating and preventing the propagation of cracks if they occur, and has the secondary effect of adjusting the coefficient of thermal expansion and increasing the hardness.

The flaky ceramic in the ceramic filler uses one or more of mica, alumina, and iron oxide, and has the same effect as whiskers.

Therefore, as the ceramic filler, fine ceramics, whiskers, and flaky ceramics may be used alone, but the effect is greater when used in combination.

In addition, in the thin metal protective coating formed by thermal spraying one or more of metal, ceramic, and glass, the thermal sprayed layer has pores, so cracks do not occur due to thermal expansion, and it has excellent wear resistance. It is particularly effective against fusing and cracking of thin metal coatings caused by scratches caused by nylon scrubbers and metal scrubbers during cleaning.

When metal is sprayed, oxides are formed on the surface of the sprayed layer, increasing its hardness. Suitable metals are those that have high strength, are stable up to high temperatures, and have excellent corrosion resistance, and stainless steel is particularly desirable.

When ceramics are thermally sprayed, one or more types of especially high hardness nium titanates may be used.

When glass is thermally sprayed, its hardness is relatively high and it has sufficient wear resistance, but adhesion may be poor when glass is used alone, and when used in conjunction with metal or ceramics, it reduces pores and improves strength. It is good because it can increase the

Therefore, materials to be thermally sprayed include metals, ceramics,
Each of the glasses may be used alone, but the effect will be greater when used in combination.

Regarding the manufacturing method of non-metallic containers for heating cookers,
There are three possible methods depending on the timing of transfer and firing, each with its own characteristics.

A manufacturing method in which a thin metal coating is transferred to the bottom of a non-metallic container and fired, and then a thin metal protective coating is further transferred and fired is superior in that it can be manufactured stably. , there is a drawback that the manufacturing cost is high because of two transfers and two firings.

In addition, a manufacturing method in which a thin metal coating is transferred to the bottom of a non-metallic container, a protective coating of the thin metal coating is further transferred, and then baked is a method that requires less baking cost.
It has a defect in adhesion at the interface between transfers and is easily peeled off.

Furthermore, a manufacturing method in which the thin metal coating and the thin metal protective coating are transferred from an integrated transfer paper to the bottom of a non-metallic container, and then fired, has a low firing cost and requires only one transfer. However, the disadvantage is that the cost of baking management and transfer paper is high.

Note that the transfer paper for transfer has an organic binder, solvent, oil, and resin for the overcoat layer, and baking eliminates these organic substances, so it cannot be used for the thin metal coating or the overcoat layer. It is capable of forming a thin metal film protective film.

The above manufacturing steps are carried out depending on the materials used.

In addition, when forming a thin metal protective coating by thermal spraying, stable production can be achieved by performing thermal spraying after transferring and baking the thin metal coating.

As described above, the characteristics of the non-metallic container for a heating cooker of the present invention will not be impaired during cooking using a gas stove, an electric stove, an induction heating cooker, etc., especially under abnormal usage conditions such as dry cooking or burnt state. is gone.

In addition, in the above explanation, we have mainly explained the shape of a clay pot, but it is not limited to this shape. For example, the same effect can be achieved with a shape of a ceramic plate, a plate, a casserole, etc. Needless to say, it has.

In addition, in consideration of use in induction heating cookers, it is possible to use non-metallic containers for heating cookers in which ferrite, etc. is fixed to the center of the bottom of the non-metallic container using methods such as gluing to enable electricity to flow. good.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

In the figure, 1 is the earthenware pot body which is a non-metallic container of size 8, and the dimensions of this earthenware pot body 1 are 261mm in diameter. Bottom diameter is 18CM, height is 10cIs, average wall thickness is 411cm.
If+. A thin metal coating 2 of 10 to 40 microns is formed on the outer surface of the bottom of the earthenware pot body 1, and a protective thin metal coating 3 of 10 to 100 microns is further formed on the outside thereof.

The materials used for the thin metal coating 2 and the thin metal protective coating 3 are shown in Table 1, and the materials shown in the conventional example are marked with * in Table 1. In Table 1, the term "glass" refers to borosilicate glass.

The numbers in the thin metal coating column indicate the weight percent of glass contained in the silver layer.

Inorganic pigments have been omitted.

When the non-metallic container for a heating cooker of the present invention having the above configuration is placed on the plate of an induction heating cooker and the power is turned on, lines of magnetic force are generated from the heating coil, and the lines of magnetic force are formed on the outer surface of the bottom of the earthenware pot body 1. The liquid flows through the thin film metal coating 12. As a result, eddy currents are generated, heat is generated, and the heat is transferred to the inside of the earthenware pot body 1.

Next, the effects of the earthenware pot of the present invention will be explained in comparison with a conventional example.

If an earthenware pot with the configuration shown in Table 1 is placed on an induction heating cooker and can withstand dry cooking for 60 minutes,
A 60-minute scorching test was conducted using two sog rice cakes. The presence or absence of cracks in the thin metal protective coating 3 was determined after one scorching test was completed. The scorching test was then repeated up to 20 times, and when there was melting or cracking in the earthenware pot body, the number of repetitions was indicated, and those that withstood 20 times were indicated as O.

In addition, for cleaning of boiled spills, apply 5 cc of Kikkoman's Tokuchi soy sauce to the outside of the bottom of the earthenware pot with the configuration shown in Table 1, pour 1 liter of water into the earthenware pot, and heat it in an induction heating cooker. After heating for 60 minutes, it was washed with water while scrubbing with a nylon scrubber, and the degree of staining was evaluated. The mark O indicates that there is almost no stain, the mark Δ indicates that the stain is somewhat difficult to remove, and the mark X indicates that the stain does not come off at all.

(% lower) (Continued Table 1) (Continued) Table 1 (Continued) As is clear from Table 1, most of the conventional earthenware pots do not crack when they are boiled dry, and the earthenware pot itself is the material of the present invention, and the other constituent materials are the same as conventional ones,
Although the cracking caused by dry cooking disappeared, an abnormality occurred when the scorching test was repeated. However, the earthenware pot constructed according to the present invention had durability of more than 20 repetitions of the scorching test, and showed excellent characteristics even under abnormal use. Furthermore, in terms of cleaning performance with a nylon scrubber, the sprayed version was slightly inferior, but the transfer version showed excellent cleaning performance.

Incidentally, materials made of materials not shown in Table 1 of the present invention also showed equivalent performance.

Furthermore, the clay pot of the present invention showed excellent performance in similar tests using an electric stove or a gas stove.

Effects of the Invention As is clear from the description of the above embodiments, according to the present invention, at the bottom of a non-metallic container containing eucryptite, aluminum titanate, or a mixture of both as a product,
A thin metal coating containing silver as the main component and 20% by weight or less of glass frit is formed, and a protective thin metal coating is formed on the outside of the coating, which prevents abnormal usage conditions such as dry cooking and burning. Also, it is possible to provide a non-metallic container for a cooking device whose properties are not impaired.

[Brief explanation of the drawing]

The figure is a sectional view of a non-metallic container for a heating cooker showing an embodiment of the present invention. 1...Earthen pot body (non-metallic container), 2...
... Thin metal coating, 3... Thin metal coating protective coating. Name of agent: Patent attorney Shigetaka Awano and 1 other person! −
Non-metallic container 2 - Thin film all

Claims (13)

[Claims] (1) Forming a thin metal coating mainly composed of silver and containing 20% by weight or less of glass frit on the bottom outer surface of a non-metallic container mainly composed of eucryptite, aluminum titanate, or a mixture of both; A non-metallic container for a heating cooker further comprising a thin metal protective film formed on the outside thereof. (2) Thin metal coating The non-metallic container for a cooking device according to claim 1, wherein the protective coating is made of glass, a ceramic filler, and an inorganic pigment, and contains at least 30% by weight of glass. (3) The non-metallic container for a cooking device according to claim 2, wherein the ceramic filler is one or more of fine ceramics, whiskers, and scale-like ceramics. (4) The non-metallic container for a heating cooker according to claim 3, wherein the fine ceramic particles are made of eucryptite, aluminum titanate, or a mixture of both. (5) Whiskers are potassium titanate, α-alumina,
4. The non-metallic container for a cooking device according to claim 3, wherein one or more of beryllia, boron carbide, silicon carbide, and silicon nitride is used. (6) The non-metallic container for a cooking device according to claim 3, wherein the scale-like ceramic is made of one or more of mica, alumina, and iron oxide. (7) Thin metal coating The protective coating can be made of metal, ceramics,
The non-metallic container for a heating cooker according to claim 1, which is formed by thermal spraying one or more types of glass. (8) The non-metallic container for a heating cooker according to claim 7, wherein the metal is made of stainless steel. (9) Claim 7 in which the ceramic uses one or more of alumina, silica, zirconia, zircon, cordierite, eucryptite, and aluminum titanate.
Non-metallic container for heating cooker as described. (10) A method for manufacturing a non-metallic container for a cooking device, which comprises transferring a thin metal coating to the bottom of the non-metallic container and baking it, and then further transferring and baking a thin metal protective coating. (11) A method for producing a non-metallic container for a cooking device, which comprises transferring a thin metal coating to the bottom of the non-metallic container, further transferring a thin metal coating protective coating, and then firing these. (12) Transfer the thin metal coating and the thin metal protective coating from the integrated transfer paper to the bottom of the non-metallic container, and then
A method for manufacturing a non-metallic container for a heating cooker formed by firing. (13) A method for producing a non-metallic container for a cooking device, which comprises transferring a thin metal coating to the bottom of the non-metallic container, baking it, and then forming a protective thin metal coating by thermal spraying.