JP2007227191A - Induction heating element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating element easily manufacturable, having flexible usefulness, and capable of providing a high heating temperature in a short time; and to provide its manufacturing method. <P>SOLUTION: This induction heating element is provided with a body made of a nonmetal inorganic material, and a heat generation layer formed on a surface of the body and containing ferrosoferric oxide and a nonmetal inorganic material. In this manufacturing method of the induction heating element, a slurry-like layer containing ferrosoferric oxide and a nonmetal inorganic material is applied to a surface of the body made of a nonmetal inorganic material, and thereafter the heat generation layer is formed by drying and baking it. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generally relates to a dielectric heating element and a manufacturing method thereof, and more particularly to a dielectric heating element that heats an object itself by the action of a microwave output from a microwave oven or the like, and a manufacturing method thereof. Is.

  Conventionally, as a heating element that generates heat by dielectric heating, a microwave-absorbing heating element for cooking a microwave oven to moderately burn a product to be cooked is described in, for example, Japanese Patent Laid-Open No. 8-231262 (Patent Document 1). As it is known. This microwave absorption heating element for cooking in a microwave oven is a sintered body obtained by firing a mixture of 20 to 70% by weight of iron trioxide and the balance being clay. Moreover, the manufacturing method of this microwave absorption heating element for microwave oven cooking is the atmosphere whose temperature is 1100-1500 degreeC and oxygen concentration is 5% or less in the mixture which consists of 20-70 weight% of triiron tetroxide and the remainder clay. It is the method of baking inside.

  Moreover, the heating tray for microwave ovens which does not have a possibility of being damaged by the heating cooking in a microwave oven is described in Unexamined-Japanese-Patent No. 2001-128847 (patent document 2), for example. This heating pan for a microwave oven transfers the heating medium material to the bottom of the dish body having a glaze layer on the surface, and bakes it at the melting temperature of the flux layer, thereby the flux of the glaze layer of the dish body and the heating medium material. The layers are fused and integrated, and a thin film of exothermic material is integrally attached and fixed to the bottom of the dish body. The above heating medium is composed of a transfer paper structure in which a flux layer, a ferrite layer, and a flux layer are sequentially printed on a backing sheet, the ferrite layer is sandwiched between the flux layers, and the surface is covered with a cover coat. It is a thing.

  Furthermore, tableware for microwave ovens is described in, for example, Japanese Patent Laid-Open No. 7-88032 (Patent Document 3). This tableware for a microwave oven is a table made of a ceramic material in which a heating element mainly composed of ferrite is embedded.

  Furthermore, a microwave absorption heating element is described in, for example, Japanese Patent No. 3708225 (Patent Document 4). This microwave absorption heating element is obtained by dispersing a ferrite material having a particle size distribution peak adjusted to 3 to 5 μm and a ferrite material having a particle size distribution peak adjusted to 10 to 50 μm in a heat resistant polymer material. It is a thing.

  For example, a microwave heating element described in JP-A-8-309276 (Patent Document 5) is obtained by applying and drying a heat-resistant resin solution in which titanium oxide powder or ferrite powder is dispersed in a ceramic molded body. .

  A microwave absorbing and exothermic cooking container described in Japanese Patent Laid-Open No. 9-249269 (Patent Document 6) is a micro having self-temperature controllability on the outer surface of a cooking container base material through which microwaves can pass. A wave exothermic metal oxide layer is provided.

Moreover, a dish for a microwave oven with no energy loss is proposed in, for example, Japanese Patent Laid-Open No. 5-21155 (Patent Document 7). In this microwave oven dish, an electromagnetic wave absorber is formed on the surface of a rotating dish body made of metal, glass or earthenware. As the material of the electromagnetic wave absorber, a ferrite electromagnetic wave absorber, a carbon electromagnetic wave absorber, a dielectric electromagnetic wave absorber, a carboferrite electromagnetic wave absorber, or another electromagnetic wave absorber is used.
JP-A-8-231262 JP 2001-128847 A Japanese Patent Laid-Open No. 7-88032 Japanese Patent No. 3708225 JP-A-8-309276 JP 9-249269 A JP-A-5-21155

  However, a dielectric heating heating element that generates heat up to about several hundred degrees Celsius in a short time by dielectric heating, particularly microwave heating, has not been manufactured and sold.

  The heating element described in Japanese Patent Laid-Open No. 8-231262 (Patent Document 1) uses triiron tetroxide as its material, but is composed of a lump of sintered body. For this reason, in order to maintain the shape-retaining property as a lump at the time of firing shrinkage, the content of iron trioxide is limited to 70% by weight or less. Therefore, a high exothermic temperature cannot be obtained in a short time. In addition, since the firing atmosphere is limited, the production cost increases when industrially producing. Furthermore, since the appearance of the obtained heating element becomes black, this heating element is inappropriate as a ceramic product.

  Moreover, the thin film of the exothermic substance fixed to the bottom part of the plate body described in Japanese Patent Application Laid-Open No. 2001-128847 (Patent Document 2) forms a ferrite layer sandwiched between flux layers by transfer. For this reason, a thin film of a pyrogen can be formed only on a heat-resistant container with a glaze, and the entire inside of the container including the side surface of the container cannot be covered with a thin film of a pyrogen. Moreover, although a thin film of a heat generating material can be fixed to the flat surface of the container, the thin film cannot be fixed to a complicated curved surface of the container. Furthermore, since the thickness of the ferrite layer as the exothermic material formed is as thin as about 20 μm, a high exothermic temperature cannot be obtained in a short time.

  Furthermore, since the tableware for microwave ovens described in JP-A-7-88032 (Patent Document 3) is configured by embedding a heating element, the manufacturing method is not easy and a sufficient calorific value is obtained. Is difficult.

  Furthermore, the microwave heating element described in Japanese Patent No. 3708225 (Patent Document 4) and Japanese Patent Application Laid-Open No. 8-309276 (Patent Document 5) disperses the heating element material in a polymer material or resin. Therefore, it cannot be fired at a high temperature after coating, and cannot withstand a high temperature of several hundred degrees Celsius in practical use. Moreover, it is difficult to obtain a sufficient calorific value with these microwave heating elements.

  In addition, in the microwave absorption exothermic cooking vessel described in JP-A-9-249269 (Patent Document 6), a high exothermic temperature cannot be obtained in a short time.

  In addition, even a microwave oven dish described in JP-A-5-21155 (Patent Document 7) can only obtain a heat generation temperature of about 130 ° C., and it is difficult to obtain a sufficient heat generation amount.

  Accordingly, an object of the present invention is to provide a dielectric heating heating element that can be easily manufactured, has flexible practicality, and can obtain a high heating temperature in a short time, and a manufacturing method thereof. is there.

  Based on the examination of the problems in the background art described above, the present inventor has studied earnestly by examining the configuration of a dielectric heating heating element, particularly a heating element by microwave heating, from various aspects. As a result, it was found that a higher heat generation temperature can be achieved in a short time by limiting the heat generation material to iron trioxide and forming the heat generation material in a layered form. The present invention has been made based on such knowledge of the inventors.

  A dielectric heating heating element according to the present invention includes a main body made of a nonmetallic inorganic material, and a heat generating layer formed on the surface of the main body and containing iron trioxide and a nonmetallic inorganic material.

  In the dielectric heating heating element of the present invention, the heating element that generates a heating action is formed in a layered form on the surface of the main body made of a nonmetallic inorganic material. Further, the heating element includes triiron tetroxide and a nonmetallic inorganic material. Thereby, a heat generating layer can be easily formed on the surface of the main body made of non-metallic inorganic materials having various shapes, and a high heat generating temperature can be obtained in a short time.

  In the dielectric heating element according to the present invention, the heat generating layer preferably contains 70 mass% or more of iron trioxide.

  By doing in this way, a high exothermic temperature can be obtained in a short time. Moreover, although the heat generating layer contains 70 mass% or more of iron trioxide, the shape of the layer can be maintained after firing.

In the dielectric heating element of the present invention, the amount of iron trioxide attached per unit surface area of the main body is preferably 15 mg / cm ² or more.

  By doing in this way, a high exothermic temperature can be obtained in a short time.

Furthermore, in the dielectric heating element according to the present invention, the adhesion amount of iron trioxide per unit surface area of the main body is preferably 30 mg / cm ² or more and 70 mg / cm ² or less.

  By doing in this way, a high exothermic temperature can be stably obtained in a short time.

  In the dielectric heating element according to the present invention, the heat generating layer is preferably formed directly on the surface of the main body.

  In the dielectric heating element according to the present invention, the heating layer is preferably formed on the surface of at least a part of the main body.

  In the dielectric heating heating element of the present invention, the heating layer may be formed on the surface of the main body according to a predetermined pattern.

  The dielectric heating heating element of the present invention may further include a non-metallic inorganic material layer formed on the surface of the heating layer.

  Moreover, the dielectric heating heating element of the present invention may further include a glaze layer formed on the surface of the heating layer.

  The method for manufacturing a dielectric heating element according to the present invention is a method of applying a slurry-like layer containing triiron tetroxide and a nonmetallic inorganic material on the surface of a main body made of a nonmetallic inorganic material, followed by drying, A heat generating layer is formed by firing.

  As described above, according to the present invention, the heat generating layer can be easily formed on the surface of the main body made of the nonmetallic inorganic material having various shapes, and a high heat generating temperature can be obtained in a short time.

  As a main body made of a nonmetallic inorganic material, for example, a microwave absorbing heat generation layer mainly composed of iron trioxide is formed as a heat generation layer on the surface of a ceramic or ceramic main body.

  The microwave absorbing heat generating layer is formed as follows. First, triiron tetroxide and a non-metallic inorganic material such as clay, feldspar, silica, and petalite are mixed. To this mixture, water is added to a mixture of a viscous component such as CMC (methyl cellulose carboxylate) or PVA (polyvinyl alcohol) and paste, and if necessary, a dispersant is added and stirred well to disperse uniformly. Let In this way, a slurry mixture is prepared. Here, the slurry refers to a solid in which a solid is dispersed in a liquid and a mass ratio of the solid is 5 to 90% by mass. Thereafter, the slurry-like mixture is applied onto a ceramic or ceramic body, dried, and then fired to form a heat generating layer.

  The ceramic body may be a green body of any shape, an unfired body, or a sintered body. The method of applying the slurry mixture is not particularly limited, but the slurry mixture is poured along the surface of the ceramic body, the ceramic body is immersed in the slurry mixture, or the like. The slurry-like mixture may be partially applied on the surface of the ceramic body to form a pattern, or the slurry-like mixture may be sprayed onto the ceramic body by spraying. In this way, a slurry-like mixture can be applied onto the surface of a ceramic body of any arbitrary shape.

  As described above, a slurry-like mixture layer of any thickness can be deposited on the surface of a ceramic body, dried, and then fired in the same way as a normal ceramic product. A ceramic heating element such as a ceramic container is obtained.

  At this time, by forming a non-metallic inorganic material layer and / or a glaze layer on the slurry-like mixture layer, for example, by applying a cosmetic mud or a glaze, the appearance of a normal ceramic product Is obtained.

  Further, the firing atmosphere for forming the heating element of the present invention does not need to be an inert atmosphere such as argon or nitrogen, or a reducing atmosphere such as hydrogen, and there is no problem even in an air atmosphere.

  In order to control the heat generation amount of the heating element of the present invention, the mass ratio of iron trioxide contained in the heat generation layer and / or the amount of iron trioxide attached per unit area of the ceramic body, that is, Control the amount of iron tetroxide deposited per unit area of the slurry mixture layer.

  In order to obtain a high heat generation amount and, as a result, a high heat generation temperature in a short time, the mass ratio of triiron tetroxide is 70 mass% or more. If the mass ratio of triiron tetroxide increases, it becomes possible to obtain a high calorific value. However, the greater the mass ratio of triiron tetroxide, the more difficult it is to carry out the process after preparing the slurry mixture. For example, problems such as difficulty in applying a slurry-like mixture layer and cracks in the layer after firing occur. For this reason, 70 mass%-90 mass% are preferable, and, as for the mass ratio of triiron tetroxide, More preferably, they are 70 mass%-80 mass%.

Further, in order to obtain a high heat generation amount and, as a result, a high heat generation temperature in a short time, the adhesion amount of iron trioxide per unit area of the ceramic body is set to 15 mg / cm ² or more. If the adhering amount of triiron tetroxide is 15 mg / cm ² or more, it is possible to obtain a high calorific value, that is, to achieve a high exothermic temperature in a short time. As the amount increases, it becomes more difficult to carry out the step after the slurry-like mixture is produced, for example, it becomes difficult to apply the layer of the slurry-like mixture, and the layer is cracked after firing. With to solve this problem, in order to stably obtain a short time at high heating temperatures, forty-three deposition amount of the iron oxide 30mg ^/ cm ² ~70mg ^/ cm 2 is preferred.

  When the dielectric heating heating element of the present invention is heated by the action of microwaves output from a microwave oven, the heating rate of the portion where the heat generating layer is attached increases as the area of the heat generating layer attached decreases.

  As a whole, the adhesion area of the heat generation layer may be substantially constant, and the slurry-like mixture layer may be applied continuously on a certain area, or the adhesion area may be divided to form a slurry-like mixture layer. May be applied. In this case, by dividing the adhesion region and applying a slurry-like mixture layer, the amount of iron trioxide attached can be easily controlled, and the amount of heat generated by the heat generation layer can be easily controlled. .

  Depending on the shape and dimensions of the actual product, that is, the shape and dimensions of the ceramic body, how to apply the slurry-like mixture layer, that is, the application area, the application amount, and the application form (continuous application, divided application) Etc. can be changed.

  When the dielectric heating heating element of the present invention manufactured as described above, for example, a ceramic product is put in a microwave oven and heated, the temperature of the ceramic product can be burnt, for example, on the food placed on the ceramic product. Rises to a possible temperature in a short time.

  As described above, the dielectric heating element according to the present invention can be used for a food cooking container by taking advantage of the fact that a high exothermic temperature can be obtained in a short time. In this case, a heating layer is formed on the inner surface of the ceramic container, the container is heated for several minutes in a microwave oven, and then the food is placed in the container and further heated in the microwave to output in the microwave oven. The heating action of both the heating of the food itself by the action of microwaves and the heating of the food by far-infrared rays through a ceramic container heated by generating heat by the action of microwaves output in the microwave oven Can be expected. By performing such a cooking method, cooking that could not be cooked with a microwave oven alone until now is also possible. Examples of such dishes include grilled fish and grilled potatoes.

  When cooking grilled fish in a microwave oven alone, only the moisture of the fish is heated, so the surface of the fish is not burnt. Moreover, the grilled fish cooked by the microwave oven alone is not sufficient even when eaten.

  When cooked potatoes are cooked in a microwave oven alone, the potatoes become soft but not sweet enough. This is because sweetness does not increase because microwave heating cannot maintain the temperature at which the potato enzyme converts starch into sugar.

  By using the cooking container to which the dielectric heating heating element of the present invention is applied, cooking is performed by converting microwave energy into far-infrared rays through a ceramic container heated by generating heat by the action of microwaves. be able to. If the residual heat of the ceramic container is used, the surface of the fish can be burnt and the temperature at which the potato enzyme works can be maintained, so that the sweet baked potato can be cooked.

  The heating layer in the dielectric heating element of the present invention is preferably formed directly on the surface of the ceramic body, but an intervening layer such as a non-metallic inorganic material layer is formed on the surface of the ceramic body. It may be formed on this intervening layer. Moreover, the heat generating layer should just be formed on the surface of at least one part of the ceramic main body, and may be formed in the inner surface and / or outer surface of the ceramic main body. Further, the heat generating layer may be formed on the surface of the ceramic body according to a predetermined pattern, or may be formed on the surface of the ceramic body in a pattern, for example, a net pattern. If it does in this way, a burnt pattern can be given to foodstuffs using the dielectric heating heating element of the present invention. It is also possible to form a branding mark on the surface of food by heating a dielectric heating element with a heating layer patterned on the surface of a ceramic body in a microwave oven and then pressing it on the surface of the food. is there. In this case, the pattern may be a character or the like.

  In addition, many uses other than the container for cooking can be considered as a use of the dielectric heating heating element of this invention. As an example, it can be considered that the dielectric heating element of the present invention is used as a health device such as a ceramic iron or hot stone.

Example 1
In order to compare iron trioxide used as a material for the heat generating layer in the dielectric heating element of the present invention with other heat generating materials, the following tests were performed.

  After applying and drying a slurry-like mixture layer containing various exothermic substances on the surface of a ceramic test piece (fired at a temperature of 800 ° C.) having a thickness of 12 mm and a size of 50 mm × 45 mm And firing at a temperature of 1200 ° C. The various dielectric heating elements obtained were heated in an microwave oven at an output of 500 W for 20 seconds, and the temperature reached after heating was measured. The ultimate temperature was measured three times, and the average value is shown in Table 1 as the measurement result.

  The slurry mixture was prepared by adding 0.4 mass% CMC and water to various exothermic substances and petalite shown in Table 1 below and mixing them. The exothermic substance [% by mass] in Table 1 represents the mass ratio of exothermic substance / (exothermic substance + petalite). The coating thickness of the slurry mixture layer was kept constant at about 0.3 mm.

  The iron trioxide used as the exothermic material used in Example 1 of the present invention was magnetic sand iron # 200 manufactured by Kinsei Matec Co., Ltd.

  As the microwave oven, a model RE-15V5 manufactured by Sharp Corporation was used. The thermometer used was Hioki Model 3412-50 as the main body and Hioki Model 9181 as the probe.

  From the results shown in Table 1, it can be seen that when exothermic materials are formed in layers on earthenware, iron trioxide has a higher calorific value than other exothermic materials, and the exothermic temperature reaches 200 ° C. or higher.

(Example 2)
The following tests were conducted by changing the mass ratio of iron trioxide used as the material of the heat generating layer in the dielectric heating element of the present invention.

  A layer of a slurry-like mixture containing triiron tetroxide was applied on the surface of a ceramic test piece (fired at a temperature of 800 ° C.) having a thickness of 12 mm and a size of 50 mm × 45 mm, and dried. Thereafter, it was fired at a temperature of 1200 ° C. The various dielectric heating elements thus obtained were heated in an microwave oven at an output of 600 W for 20 seconds, and the temperature reached after heating was measured. The ultimate temperature was measured four times, and the average value is shown in Table 2 as the measurement result.

  The slurry mixture was prepared by adding CMC 0.4% by mass and water to iron trioxide tetraoxide and petalite in the mass ratio shown in Table 2 below and mixing. The triiron tetroxide [mass%] in Table 2 shows the mass ratio of triiron tetroxide / (iron tetroxide + petalite). The coating thickness of the slurry-like mixture layer was kept constant at about 0.25 mm.

  The iron trioxide used in Examples 2 to 6 and Comparative Examples 14 to 17 of the present invention was magnetic sand iron # 200 manufactured by Kinsei Matec Corporation.

As the microwave oven, model NE-S33F manufactured by Matsushita Electric Industrial Co., Ltd. was used. The thermometer used was a thermoview of a model TVS-600 manufactured by AVIO.

  From the results shown in Table 2, it can be seen that when the mass ratio of triiron tetroxide is 70% by mass or more, the heat generation amount is high and the heat generation temperature reaches about 200 ° C.

(Example 3)
The following tests were conducted by changing the amount of iron trioxide used as the material of the heat generating layer in the dielectric heating element of the present invention.

  A layer of a slurry-like mixture containing 75% by mass of iron trioxide is applied on the surface of a test piece made of earthenware having a thickness of 8 mm and a size of 54 mm × 48 mm (baked at a temperature of 800 ° C.), After drying, it was fired at a temperature of 1200 ° C. The obtained various types of dielectric heating elements were heated in an microwave oven at an output of 600 W for 10 seconds for 20 seconds, and the temperature reached after heating was measured. The temperatures reached after heating for 10 seconds and after heating for 20 seconds were measured three times, and the average values are shown in Table 3 as measurement results.

  In Examples 7 to 16 shown in Table 3 below, slurry-like mixtures were prepared by adding 75 g of iron trioxide and 25 g of petalite to 0.5 g of CMC and 70 g of water and mixing them. And Comparative Examples 18 and 19 were prepared by adding 3.0 g of CMC and 360 g of water to 75 g of iron trioxide and 25 g of petalite and mixing them.

The adhesion amount [mg / cm ² ] of iron tetroxide per unit area in Table 3 was calculated as follows. By changing the number of times of application of the slurry-like mixture layer and changing the amount of ferric tetroxide, the amount of ferric tetroxide applied per unit area is calculated from the applied area, and the iron tetroxide per unit area is calculated. The amount of adhesion was calculated.

  The iron trioxide used in Examples 7 to 18 and Comparative Examples 18 and 19 of the present invention was magnetic sand iron # 200 manufactured by Kinsei Matech Corporation.

As the microwave oven, model NE-S33F manufactured by Matsushita Electric Industrial Co., Ltd. was used. The thermometer used was a thermoview of a model TVS-600 manufactured by AVIO.

表３に示す結果から、四三酸化鉄の付着量が１５ｍｇ／ｃｍ^２以上のとき、発熱量が高く、加熱開始１０秒後に発熱温度が１００℃程度以上に到達することがわかる。

From the results shown in Table 3, it can be seen that when the adhesion amount of triiron tetroxide is 15 mg / cm ² or more, the heat generation amount is high, and the heat generation temperature reaches about 100 ° C. or more 10 seconds after the start of heating.

  It should be considered that the embodiments and examples disclosed above are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims. .

Claims (10)

A body made of non-metallic inorganic material;
A dielectric heating heating element comprising a heating layer formed on the surface of the main body and containing iron trioxide and a nonmetallic inorganic material.   The dielectric heating element according to claim 1, wherein the heat generation layer contains 70 mass% or more of iron trioxide. The dielectric heating heating element according to claim 1 or ² , wherein an adhesion amount of iron trioxide per unit surface area of the main body is 15 mg / cm ² or more. The dielectric heating heating element according to claim 1 or 2, wherein an adhesion amount of triiron tetroxide per unit surface area of the main body is 30 mg / cm ² or more and 70 mg / cm ² or less.   The dielectric heating heating element according to any one of claims 1 to 4, wherein the heating layer is directly formed on a surface of the main body.   The dielectric heating heating element according to any one of claims 1 to 5, wherein the heating layer is formed on a surface of at least a part of the main body.   The dielectric heating element according to any one of claims 1 to 5, wherein the heat generating layer is formed on a surface of the main body according to a predetermined pattern.   The dielectric heating heating element according to any one of claims 1 to 7, further comprising a non-metallic inorganic material layer formed on a surface of the heating layer.   The dielectric heating heating element according to any one of claims 1 to 8, further comprising a glaze layer formed on a surface of the heating layer.   A dielectric heating heating element in which a heat generating layer is formed by applying a slurry-like layer containing ferric tetroxide and a nonmetallic inorganic material on the surface of a main body made of a nonmetallic inorganic material, followed by drying and firing. Manufacturing method.