JP2010014355A - High-frequency heating element, cooking utensil for high-frequency heating apparatus using the same, and high-frequency heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when an existing high-frequency heating element composed of a ferrite material having a low Curie temperature and rubber reaches the Curie temperature, the speed of a temperature rise is decelerated when a magnetic loss is decreased, thus causing an object to be heated to hardly be browned. <P>SOLUTION: A high frequency heating element 3 comprises an acicular-grained high-frequency absorbing material 5 having no phase transition at a temperature of not higher than 400°C. A quick rise to a cooking temperature can brown an object to be heated appropriately, and can prevent overheating to make the object to be heated tasty. A cooking utensil for a high-frequency heating apparatus can secure the performance of the appreciable temperature rise of the high-frequency heating element 3 to shorten a cooking time and to save energy. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high-frequency heating element that generates heat by a high frequency used in a microwave oven or the like, a cooking utensil for a high-frequency heating device that can burn the surface of an object to be heated by high-frequency heating, and a high-frequency heating cooker.

  Conventionally, this type of high-frequency heating element and cooking utensils for high-frequency heating equipment include a high-frequency heating element mainly composed of ferrite affixed to the bottom surface of a heated object placing plate on which an object to be heated is placed ( For example, see Patent Document 1).

  FIG. 5 is a perspective view of a heated object mounting tray 30 to which a conventional high-frequency heating element described in Patent Document 1 is attached. The high-frequency heating element is provided on the bottom surface (not shown) of the heated object placing tray 30.

  FIG. 6 is a partial cross-sectional view of the heated object mounting tray 30 provided with the high-frequency heating element 31. As shown in FIG. 6, the high-frequency heating element 31 is provided on a painted metal base material 32 that constitutes a heated object placing tray 30.

  FIG. 7 is a schematic diagram showing the structure of the high-frequency heating element 31 described in FIG. As shown in FIG. 7, the high-frequency heating element 31 includes particles 33 of a high-frequency absorption material mainly composed of ferrite having spherical particles and a Curie temperature of 200 to 300 ° C., and a rubber material 34. 33 is in a state of being uniformly dispersed in the rubber material 34.

  When the heated object placing tray 30 on which the food is placed is placed at a predetermined position of a high frequency cooking device equipped with a magnetron that generates a high frequency and grill cooking is started, the high frequency oscillated from the magnetron is applied to the heated object. The high-frequency heating element 31 affixed to the mounting tray 30 absorbs the heat to change it into heat, and the heated object mounting tray 30 is heated. And the to-be-heated material which is contacting the heated to-be-heated material mounting tray 50 is heated, and a to-be-heated material gets burnt with progress of cooking.

In general, when grill cooking is performed, if an attempt is made to make both the deliciousness of the cooked food to be heated and a suitable burnt at the same time, the heated object placing plate 30 varies from 150 to 150, depending on the type and amount of the heated object. It is necessary to raise the temperature to 300 ° C. in a short time.
JP 2007-225186 A

  However, since the conventional high-frequency heating element 31 uses a high-frequency absorbing material mainly composed of ferrite having a Curie temperature of 200 to 300 ° C., the high-frequency absorbing material absorbs the high frequency to generate heat and rises near the Curie temperature. When heated, the high-frequency absorbing material has a problem that the magnetic loss, which is one of the magnetic characteristics due to the magnetic phase transition, is reduced, the high-frequency absorption performance is lowered, and the temperature rising rate is slow.

In addition, when the high-frequency heating element 31 made of a high-frequency absorbing material mainly composed of ferrite having a Curie temperature of 200 to 300 ° C. is used as a tool for a high-frequency heating device, it is short in order to give a burn suitable for the object to be heated. Although it is necessary to heat up the to-be-heated object mounting tray 30 in time, since the high-frequency absorption performance of a high frequency absorption material falls, the temperature rising rate of the to-be-heated object mounting dish 30 becomes slow, Therefore It takes time to moderately burn the object, the cooking time becomes longer, the overheating state of the heated object due to the longer cooking time occurs, the moisture content inside the heated object decreases, There was a problem that the taste was lost.

On the other hand, there is magnetite (Fe ₃ O ₄ ) as a material having a high Curie temperature. Magnetite has a high Curie temperature of 580 ° C., and no magnetic phase transition occurs at 300 ° C., but oxidation proceeds at a temperature of 200 ° C. or higher, and the crystal structure of hematite (Fe ₂ O ₃ ) has extremely low high-frequency absorption performance. Changes (structural phase transition). Therefore, although magnetite has a high initial high-frequency absorption performance, the high-frequency absorption performance gradually decreases due to oxidation, and thus there is a problem that stable temperature rise performance cannot be obtained in the long term.

  In addition, when a high-frequency heating element made of a high-frequency absorbing material containing magnetite as a main component is used as a device for a high-frequency heating device, the temperature rise performance of the high-frequency heating element changes with time. Appropriate burns cannot be reproduced over a long period of time, leading to user dissatisfaction.

  In addition, manual cooking is required from auto cooking to obtain suitable burned eyes, and the operation of the cooking utensils becomes complicated, and if burned eyes are given priority, the inside of the heated object will be overheated and the heated object will be delicious. Had the problem of being lost.

  The present invention solves the above-mentioned conventional problems, stabilizes the high-frequency absorbing material used for the high-frequency heating element, prevents the temperature rise performance of the high-frequency heating element from changing with time, and constantly cooks the object to be heated. An object of the present invention is to provide a high-frequency heating element capable of realizing the state, a cooking utensil for a high-frequency heating device using the same, and a high-frequency heating cooker.

  In order to solve the above-described conventional problems, the high-frequency heating element of the present invention includes a high-frequency absorbing material in which the particle shape without phase transition is needle-like at a temperature of 400 ° C. or lower.

  As a result, it is possible to prevent a decrease in high-frequency absorption performance caused by the phase transition of the high-frequency absorbing material in the operating temperature range of the object to be heated. Can be realized.

  Moreover, since the needle-shaped particles of the high-frequency absorbing material are made into a needle-like shape, the needle-like particles of the high-frequency absorbing material are in contact with each other. Current flows and Joule heat is generated. This Joule heat is added to the absorption and heat generation of the high frequency due to the dielectric loss of the high frequency absorption material, and higher temperature rise performance can be obtained.

  The cooking device for a high-frequency heater according to the present invention is provided with the high-frequency heating element according to the present invention on a metal heated object mounting tray on which a coating layer containing an organic polymer is placed. This is a configuration.

  As a result, the high-frequency heating element always has a stable and high temperature raising performance, and the metal heated object mounting tray provided with the high-frequency heating element has excellent thermal conductivity. Since the generated heat can be efficiently transferred to the object tray, the object to be heated can be appropriately burned in a short time and the water inside the object to be heated can be reduced. Overheating is prevented, and the deliciousness of the object to be heated can also be realized.

Since the high-frequency heating element of the present invention and the cooking utensil for a high-frequency heating device using the same can prevent a decrease in high-frequency absorption performance due to phase transition, it is possible to realize a high-frequency heating element excellent in temperature rise performance. This excellent temperature rise performance can be obtained stably over a long period of time.

  Moreover, since the overheating of a to-be-heated material can be prevented, the new cooking method which balances deliciousness and a moderate burn can be implement | achieved.

  According to a first aspect of the present invention, a high-frequency heating element is configured to include a high-frequency absorbing material having a needle-like shape with no phase transition at a temperature of 400 ° C. or lower, so that a high-frequency heating material caused by the phase transition of the high-frequency absorbing material A decrease in absorption performance is prevented, a stable and high temperature rise performance is always obtained, and high durability can be realized.

  In addition, since the particles of the high-frequency absorbing material have a needle-like structure, the particles are in contact with each other. Therefore, when the temperature rises, the characteristics as a semiconductor are manifested, eddy currents flow through the needle-like particles, and Joule heat is generated. appear. This Joule heat is added to the absorption and heat generation of the high frequency due to the dielectric loss of the high frequency absorption material, and higher temperature rise performance can be obtained.

  According to the second invention, in particular, the high-frequency heating element according to the first invention is composed of a composite of at least one type of high-frequency absorbing material having a needle shape and at least one type of elastomer, thereby providing the first In addition to the effects of the invention of the present invention, the high frequency absorbing material particles can be dispersed in the elastomer, so that the high frequency heating element of the high frequency heating element can be subjected to mechanical shock due to external force or dropping or thermal shock due to repeated cold heat. Dropping and destruction can be prevented.

  In the third aspect of the invention, in particular, by using ceramic whiskers or fibers as the first or second high-frequency absorbing material, the aspect ratio of the particles of the polymer absorbing material can be increased in addition to the first effect. Therefore, the number of contact points between the particles of the high-frequency absorbing material increases, and as a result, the amount of the high-frequency absorbing material used can be reduced and the cost can be reduced.

  In addition, since the high frequency absorbing material is ceramic, it has high chemical stability against water, water vapor, acid and alkali components contained in oils and fats generated during cooking, and can improve the durability and reliability of the high frequency heating element. .

  The fourth aspect of the invention is particularly a ceramic whisker or fiber that is a high-frequency absorption material of the third aspect of the invention, the main component of which is zinc oxide, silicon carbide, a ceramic material in which a metal thin film layer is formed, silicon and titanium or zirconium and carbon. By using at least one kind of ceramic material containing oxygen and oxygen, moderate conductivity expressed by the dielectric loss and semiconductor characteristics of these materials is suitable for high frequency absorption, and high high temperature heating performance is achieved. Obtainable.

  According to a fifth aspect of the present invention, in particular, in the high-frequency absorption material of any one of the first to fourth aspects, a coating layer having a hydrophobic outer surface is formed on the surface of the high-frequency absorption particles. Since the kneadability with the elastomer is improved and the particles of the high-frequency absorbing material can be uniformly dispersed in the elastomer, the heating surface of the high-frequency heating element can have a uniform temperature distribution, and cooking for high-frequency heating equipment When applied to an instrument, it is possible to uniformly apply the burned object to be heated.

  In addition, since the particles of the high frequency absorbing material are uniformly dispersed in the elastomer, flexibility can be obtained in these composites. Flowability is improved, a uniform film thickness can be obtained, and heat generation characteristics can be stabilized.

  The sixth invention is particularly durable because it has excellent heat resistance and chemical resistance by using silicon rubber or fluororubber as the elastomer of any one of the first to fifth inventions. A highly reliable high-frequency heating element can be realized.

  In the seventh invention, in particular, by setting the content of the high-frequency absorbing material of any one of the first to sixth inventions to 20 to 60% by volume, high-frequency absorption performance and mechanical strength of the high-frequency heating element, Adhesion with the substrate can be improved.

  In an eighth aspect of the present invention, as a cooking utensil for a high-frequency heating device, a heated object placing plate is placed on a metal heated object placing plate on which a coating layer containing an organic polymer is placed. By providing the high-frequency heating element of any one of the first to seventh inventions on a part of the surface on which the object to be heated is not placed, it is possible to always realize a stable and high temperature raising performance.

  Moreover, since the metal heated object mounting tray provided with the high frequency heating element has excellent thermal conductivity, the heat generated by the high frequency heating element can be efficiently transmitted to the heated object mounting dish. In addition to being able to burn the object to be heated in a short time, overheating of the object to be heated can be prevented, and moisture inside the object to be heated can be maintained, and both deliciousness and moderate burn can be achieved. A new cooking method can be realized.

In the ninth aspect of the invention, in particular, in the high-frequency heating element of the eighth invention, the area of the high-frequency heating element provided on the metal heated object mounting tray is set to 0.1 m ² or less so that predetermined power consumption is achieved. The heated object placing tray and the heated object placed thereon can be heated to a predetermined temperature in a short time at a high frequency, and cooking time can be shortened and energy can be saved.

  In the tenth aspect of the invention, in particular, the heat transfer to the dish to be heated due to the increase of the film thickness by setting the film thickness of the high-frequency heating element of the eighth or ninth invention to 0.5 to 2 mm. And a decrease in the heating rate due to an increase in the heat capacity of the high-frequency heating element itself, and a decrease in the high-frequency absorption performance of the high-frequency heating element due to the thin film thickness can be suppressed. The heat generated by the heating element absorbing the high frequency can be efficiently transmitted to the object to be heated and the object to be heated, and cooking time can be shortened and energy can be saved.

  In the eleventh aspect of the invention, in particular, the high-frequency heating cooker equipped with the high-frequency heating appliance cooking appliance of the eighth to tenth invention is heated by the high-frequency heating element. Since it can be efficiently transmitted to the dish to be heated, the object to be heated can be appropriately burnt in a short time, and overheating of the object to be heated is prevented, and the object to be heated is delicious. A new cooking method that can retain moisture inside and achieve both deliciousness and moderate burn can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment. In addition, a configuration unique to each embodiment can be combined as appropriate.

(Embodiment 1)
FIG. 1 shows a cross-sectional view of a cooking utensil for a high-frequency heating device provided with a high-frequency heating element according to the first embodiment of the present invention.

  In addition, the form of FIG. 5 described by the prior art example is applied to the to-be-heated object mounting dish used as a cooking appliance for this invention high frequency heating equipment.

In FIG. 1, a cooking utensil 1 for high-frequency heating equipment includes a metal heated object placing tray 2 on which a coating layer containing an organic polymer is formed, and a part of the lower surface of the heated object placing dish 2. The high-frequency heating element 3 is provided. Moreover, the fixing member 4 for arrange | positioning in the predetermined | prescribed position in the store | warehouse | chamber of high frequency heating apparatuses, such as a microwave oven, is attached to the both ends of the to-be-heated material mounting tray 2. As shown in FIG. This fixing member 4 not only functions to position the object to be heated placing plate 2 but also to a handle for carrying and taking out, and the metal object to be heated placing dish 2 of the high frequency heating cooker. It arrange | positions in the heating chamber 7 mentioned later, and has the function of spark prevention at the time of supplying high frequency.

  FIG. 2 is a schematic diagram showing the structure of the high-frequency heating element 3.

  In FIG. 2, the high-frequency heating element 3 includes a high-frequency absorbing material 5 and an elastomer 6 in which the shape of particles having no phase transition at a temperature of 400 ° C. or less is needle-like, and the high-frequency absorbing material 5 has a needle-like shape. Therefore, the structure is such that a part of the particles are dispersed in the elastomer 6 in a state of being in contact with a part of the other particles.

  As the high-frequency absorption material 5 in which the shape of the particles is needle-like, whiskers and fibers made of a ceramic material having a large dielectric loss that is advantageous for high-frequency absorption are applied. Particularly useful are ceramic materials such as zinc oxide, silicon carbide, and titanium oxide with a metal thin film layer formed thereon, and ceramic materials containing silicon, titanium or zirconium, carbon, and oxygen.

  As a material for the elastomer 6, silicon rubber or fluorine rubber which is excellent in heat resistance under a temperature environment of 250 to 300 ° C., chemical resistance such as seasoning and water vapor, mechanical shock and heat shock is used. The main component is applied.

  Next, an embodiment of a method for producing the high frequency heating element 3 of the present invention will be described.

  The high frequency absorbing material 5 and the elastomer 6 are kneaded using a kneading processing apparatus such as an open roll or a kneader until the high frequency absorbing material 5 is uniformly dispersed in the elastomer 6, and then a crosslinking agent is added as necessary. Knead again. Next, a necessary amount of the kneaded material lump or the one that has been dispensed into a sheet with an open roll is collected, and placed on the surface of the object to be heated 2 on which the object to be heated is not placed. Perform pressure bonding and primary vulcanization. Thereafter, the cooking utensil 1 for the high-frequency heating device of the present invention in a state where the high-frequency heating element 3 is formed on the article to be heated 2 is obtained by performing heat treatment such as secondary vulcanization as necessary.

  During kneading, a heat-resistant agent for imparting further heat resistance of the high-frequency heating element 3, an anti-aging agent, an oil and fat agent for imparting flexibility, and the like may be added as necessary.

  Moreover, in order to improve the adhesiveness between the high-frequency heating element 3 and the heated object placing tray 2, the bonding surface of the high-frequency heating element 3 or the surface on which the high-frequency heating element 3 of the heated object placing dish 2 is provided. In addition, a primer having an adhesive function may be applied and the heated object placing tray 2 and the high-frequency heating element 3 may be bonded via the primer, or may be bonded in advance when the high-frequency absorbing material 5 and the elastomer 6 are kneaded. An agent may be added.

  FIG. 3 is a cross-sectional view of a high-frequency cooking device on which the cooking utensil 1 for high-frequency heating equipment according to the present invention is mounted.

In FIG. 3, the heating chamber 7 takes in and out the right wall surface 8, the left wall surface 9, the back wall surface 10, the upper wall surface 11, the bottom wall surface 12, and the object to be heated, which are metal boundary portions made of a metal material. An open / close door (not shown), which is an open / close wall surface, is formed in a substantially rectangular parallelepiped shape, and is formed so as to substantially confine the supplied high-frequency inside. The bottom wall surface 12 is provided with a narrowed section 13 having a substantially rectangular cross section, and a high frequency excitation section 14 for supplying power into the heating chamber 7 is disposed at a substantially central portion of the narrowed section 13.

  The magnetron 15 which is a high frequency generating means generates a high frequency to be fed to the heating chamber 7, and a waveguide 16 is provided between the magnetron 15 and the excitation unit 14 in order to guide the high frequency generated from the magnetron 15 to the excitation unit 14. Provided. The excitation unit 14 is provided with an antenna 17 that extends into the waveguide 16 and is coupled to a high frequency transmitted through the waveguide 16, and one end of the antenna 17 is a radiating antenna having a waveguide type directivity. The radio wave radiation means 18 is connected.

  The other end of the antenna 17 is assembled by inserting and assembling an output shaft of a motor 19 which is a driving means for driving the radio wave radiation means 18 to rotate. The radio wave radiating means 18 is driven to rotate by driving a motor 19 so that the fan-shaped upper surface is substantially parallel to the bottom surface of the diaphragm 13.

  Further, a sealing means 20 made of a radio wave transmitting material, for example, a glass-based or ceramic-based material, is provided at the opening of the aperture 13.

  A heating heater 21 is provided in the upper part of the heating chamber 7, and a convection heater unit (not shown) is provided in the inner part of the inner wall surface 10, and functions of high-frequency cooking, grill cooking, and oven cooking of an object to be heated. It has the composition which has.

  The cooking utensil 1 for a high-frequency heating device is inserted and attached into the heating chamber 7 along a rail portion 22 which is a locking means provided on the right wall surface 8 and the left wall surface 9 of the heating chamber 7.

  The heating chamber 7 is provided with a thermistor 23 for detecting the temperature in the heating chamber 7 and an infrared sensor 24 for detecting the temperature of the object to be heated, the cooking utensil 1 for high-frequency heating equipment, and the like.

  Next, the operation and action of the cooking utensil for the high-frequency heating device of the present invention will be described using the high-frequency heating cooker having the above configuration.

  When a predetermined instruction operation is performed in a state where the cooking utensil 1 for a high-frequency heating device in which an object to be heated is placed in the heating chamber 7 is locked to the rail portion 22 and the door is closed, the magnetron 15 is controlled by the control means 25. Operates to generate high frequency. The generated high frequency passes through the waveguide 16 and the excitation unit 14, passes through the sealing means 20 made of ceramic or the like from the radio wave emission means 18, and is fed into the heating chamber 7.

  The high frequency fed into the heating chamber 7 is absorbed by the high frequency heating element 3 constituting the cooking utensil 1 for high frequency heating equipment and converted into heat. The heat is transmitted to the heated object placing tray 2 constituting the cooking utensil 1 for high-frequency heating equipment, and the heated object in contact with the heated object placing dish 2 is heated.

  In general, when grill cooking is performed, when trying to make both the deliciousness of the cooked food to be heated and a suitable burnt, both the type of the heated object and the amount vary, but the heated object placing dish is 150 to It is necessary to raise the temperature to 300 ° C. in a very short time.

  Conventionally, Mn—Zn-based ferrite is used as a high-frequency absorbing material for a high-frequency heating element, and the Curie temperature of this ferrite is 200 to 300 ° C. although it varies depending on the composition. The heat generation mechanism of the ferrite material is mainly due to the magnetic loss of the material. When the high frequency is absorbed and heat-converted and reaches the Curie temperature (near), the magnetic loss decreases due to the magnetic phase transition, and the high frequency absorption performance is reduced. By decreasing, the heating rate above the Curie temperature is remarkably decreased.

As a result, it takes time to moderately burn the object to be heated, the cooking time becomes longer, the overheating state of the object to be heated occurs, the amount of moisture inside the object to be heated decreases, and the taste is delicious. Will be lost.

  On the other hand, a magnetite having a Curie temperature of 500 ° C. or higher has a fast rate of temperature rise because no magnetic phase transition occurs at 300 ° C. However, oxidation proceeds rapidly at a temperature of 200 ° C. or higher, and the crystal structure changes to hematite with low high-frequency absorption performance. Therefore, the initial high-frequency absorption performance is high, but oxidation gradually decreases high-frequency absorption performance. Changes with time. Along with this change over time, the temperature rise performance of the high-frequency heating element gradually decreases, and as the usage time becomes longer, the burns suitable for the object to be heated cannot be obtained.

  Since the high-frequency heating element 3 of the present invention uses the high-frequency absorbing material 5 having no phase transition at a temperature of 400 ° C. or lower, the high-frequency absorption performance caused by the phase transition is prevented from being deteriorated, and the heating target is heated in a short time. The object mounting tray 2 can be heated to a temperature of 150 to 300 ° C., and an appropriate burn can be given to the heated object in a short time.

  Further, in the high frequency absorbing material 5 used in the high frequency heating element 3 of the present invention, the shape of the particles is needle-shaped, which is a factor for improving the temperature rising rate. As shown in FIG. 2, the needle-like high-frequency absorbing material 5 is in contact with other particles and dispersed in the elastomer 6 in a state where they are connected. This structure is considered to increase the high-frequency absorption performance and increase the heating rate of the high-frequency heating element 3.

  Although the above reason is not clear, the high frequency absorption is not only the dielectric loss of the high frequency absorption material 5 but also the structure in which the particles are in contact with each other. Current flows and Joule heat is generated. It is considered that this Joule heat is added to the high frequency absorption and heat generation due to the dielectric loss of the high frequency absorption material 5, and higher temperature rise performance can be obtained.

  In addition, the high-frequency absorbing material 5 used in the high-frequency heating element 3 of the present invention has no phase transition at 400 ° C. or lower and does not change to another crystal structure at a high temperature. Obtained, and high durability can be realized.

  Moreover, the cooking utensil 1 for the high-frequency heating device of the present invention has the heat generated by the high-frequency heating element 3 because the heated object mounting tray 2 has excellent thermal conductivity. The heat can be efficiently transmitted to the article to be heated placing tray 2. Therefore, the to-be-heated object mounting tray 2 can be heated up to the cooking temperature of 150-300 degreeC in a short time, and a moderate burn can be attached to a to-be-heated object in a short time.

  Moreover, since the cooking utensil 1 for high-frequency heating equipment can prevent overheating of the object to be heated, it can hold moisture inside the object to be heated, which is necessary for deliciousness. A cooking method can be realized.

When the magnetron 15 is operated with power consumption of 700 to 1000 W, if the area of the high-frequency heating element 3 attached to the metal heated object mounting dish 2 is 0.1 m ² or more, the heated object mounting dish Since the area of 2 increases, the heat capacity of the cooking utensil 1 itself for the high-frequency heating device increases, and the heat dissipation loss increases due to the expansion of the heat dissipation area due to the increase in the surface area. The temperature speed becomes slow, and the optimum burnt and deliciousness of the heated object cannot be obtained.

Therefore, in order to obtain optimum burnt and deliciousness, it is desirable that the area of the high-frequency heating element 3 is 0.1 m ² or less. Moreover, since the to-be-heated material mounting tray 2 and the to-be-heated material mounted on it can be heated up to predetermined temperature in a short time by this, cooking time can be shortened and energy saving can be achieved.

  If the film thickness of the high-frequency heating element 3 is 2 mm or more, the heat capacity of the high-frequency heating element 3 is increased, the heating rate of the high-frequency heating element 3 is decreased, and the thermal resistance of the high-frequency heating element 3 is increased. Since the heat dissipation loss from the surface of the high-frequency heating element 3 is increased, the heat transfer due to heat conduction to the heated object placing tray 2 is reduced, and a fast temperature increase rate of the heated object placing plate 2 cannot be obtained. . Further, the cost increases due to the thick film thickness.

  On the other hand, when the film thickness of the high-frequency heat generating element 3 is 0.5 mm or less, the amount of the high-frequency absorbing material 5 is reduced, the high-frequency absorption efficiency is lowered, and a high temperature rising rate cannot be obtained.

  Therefore, in order to efficiently transmit the heat generated by the high-frequency heating element 3 by absorbing the high frequency to the heated object placing tray 2 and the heated object, the thickness of the high-frequency heating element 3 is in the range of 0.5 to 2 mm. Is desirable. Thus, the heated object placing tray 2 and the heated object placed thereon can be heated to a predetermined temperature in a short time, and cooking time can be shortened and energy can be saved.

  In addition, the high-frequency heating element 3 provided on the heated object placing tray 2 preferably has a composite structure of a high-frequency absorbing material 5 in which at least one kind of particle shape is a needle shape and at least one kind of elastomer 6. With this configuration, the elastomer 6 can protect the particles of the high-frequency absorbing material 5 and can realize strong adhesion to the object-to-be-heated dish 2, so that mechanical shock or cold heat caused by external force or dropping can be achieved. It can be made strong against repeated thermal shocks, and the high-frequency heating element 3 can be prevented from dropping off or being destroyed.

  Next, specific experimental examples will be described.

As the high-frequency absorbing material 5, 300 parts by weight of zinc oxide whisker (trade name: Panatetra) manufactured by Amtec Corporation, and as the elastomer 6, 100 parts by weight of silicon rubber (part number: X-30-3888-U) manufactured by Shin-Etsu Chemical Co., Ltd. A silicon rubber vulcanizing agent (product number: C-8A) was used and kneaded with an 8-inch open roll to prepare a sheet having a thickness of about 1.2 mm. The content of the high frequency absorption material 5 at this time is 40% by volume. Next, a required amount of zinc oxide whisker and silicon rubber sheets are sampled on a coated steel sheet having heat resistance on the surface, hot-pressed at 160 ° C. for 10 minutes, and subjected to adhesion treatment and primary vulcanization. It was. Then, the thing bonded to the steel plate was subjected to secondary vulcanization at 200 ° C. for 4 hours to produce the high-frequency heating element 3. The produced high-frequency heating element 3 had a film thickness of about 1 mm and an area of 0.08 m ² .

For comparison, in the case of zinc oxide whiskers, Mn—Zn having a Curie temperature of 215 ° C., magnetite (Fe ₃ O ₄ ) having a Curie temperature of 580 ° C., and spherical particles of zinc oxide having an average particle diameter of 2 μm are used as the high-frequency absorbing material. A high-frequency heating element was produced by the same method as described above. The film thickness, area, and content of the high frequency absorbing material were the same as those of the zinc oxide whisker.

  These high-frequency heating elements 3 are inserted into the heating chamber 7 along the rail portion 22 which is a locking means provided on the right wall surface 8 and the left wall surface 9 of the heating chamber 7 of the high-frequency cooking device shown in FIG. The magnetron 15 was attached and operated with a power consumption of 700 W, and high frequency was fed for 5 minutes. Then, it took out immediately and evaluated the surface temperature (average) of the surface-treated steel sheet with a thermoviewer.

As a result, the temperature of the high-frequency heating element 3 using the zinc oxide whisker of the present invention was 250 ° C. The temperature of the comparative high-frequency heating element is 210 ° C. for Mn—Zn having a Curie temperature of 215 ° C., 260 ° C. for magnetite (Fe ₃ O ₄ ) having a Curie temperature of 580 ° C., and 115 ° C. for spherical zinc oxide having an average particle size of 2 μm. there were.

  From the above results, the Mn—Zn high-frequency heating element with a Curie temperature of 215 ° C. has a lower temperature than the high-frequency heating element 3 of the present invention. This is presumably due to the fact that the time loss is reduced by the magnetic phase transition when the temperature rises and approaches the Curie temperature. In addition, the zinc oxide high-frequency heating element of spherical particles having an average particle diameter of 2 μm has the lowest temperature of 115 ° C., and even the same material as the high-frequency heating element 3 of the present invention is a zinc oxide whisker that is a needle-like particle. It was found that a higher temperature was obtained. The reason for this is as described above.

On the other hand, the magnetite (Fe ₃ O ₄ ) high-frequency heating element with a Curie temperature of 580 ° C. had a temperature after heating of 260 ° C., and exhibited higher temperature-elevating performance than the high-frequency heating element 3 of the present invention. This is presumably because the Curie temperature is high, there is no magnetic phase transition at a temperature of 250 ° C., and the high-frequency absorption performance is superior to that of zinc oxide whiskers.

Next, the high-frequency heating element 3 of the present invention using zinc oxide whiskers having excellent temperature rise performance and a magnetite (Fe ₃ O ₄ ) heating element having a Curie temperature of 580 ° C. are placed in a hot air circulation oven. A heat resistance test was conducted at 300 ° C. for 150 hours. After that, as described above, these high-frequency heating elements are inserted into the heating chamber 7 of the high-frequency heating cooker shown in FIG. 3, the magnetron 15 is operated with a power consumption of 700 W, and high-frequency power is supplied for 5 minutes. The surface temperature (average) of the surface-treated steel sheet was evaluated by a viewer.

As a result, the high-frequency heating element 3 using the zinc oxide whisker of the present invention was 250 ° C. and exhibited the same temperature raising performance as the initial stage even after the heat resistance test. On the other hand, the high frequency heating member Curie temperature 580 ° C. of magnetite (Fe 3 _{O 4)} is 230 ° C., it was found that as compared with the initial 260 ° C. Atsushi Nobori performance is deteriorated. In addition, the color of the high-frequency heating element is also changed from black to red brown. From this, magnetite (Fe ₃ O ₄ ) is oxidized by oxygen in the air, and the crystal structure changes to hematite (Fe ₂ O ₃ ). This is considered to be the cause of (structural phase transition). Because hematite has low magnetic loss and low high-frequency absorption performance, it is considered that the temperature rise performance has decreased.

  From the above, the high-frequency heating element 3 of the present invention is excellent in temperature rise performance and durability by using a high-frequency absorbing material having a needle-like particle shape without phase transition at a temperature of 400 ° C. or lower. It turned out to be excellent.

  In addition, the silicon rubber used in the present invention has excellent heat resistance under a temperature environment of 300 ° C., and also has excellent chemical resistance such as seasonings and water vapor, mechanical shock resistance, and thermal shock resistance. Therefore, it is optimal as an elastomer for the high-frequency teaching heating element 3.

  Note that, as the high-frequency absorbing material 5, a silicon carbide whisker, a ceramic whisker formed with a metal thin film layer, or a ceramic whisker containing silicon and titanium or zirconium, carbon and oxygen can be used instead of the zinc oxide whisker. Equivalent temperature rise performance and durability were obtained.

  In addition, even when the high-frequency absorbing material 5 particles were made by cutting long fibers into short fibers of several mm instead of whiskers, almost the same performance was obtained.

  Further, even when fluorine rubber was used as the elastomer 6 instead of silicon rubber, the same performance as that of silicon rubber was obtained.

If the content of the high-frequency absorbing material 5 used for the high-frequency heating element 3 is 20% by volume or less, the high-frequency absorption performance is deteriorated, and a satisfactory temperature performance as a high-frequency heating element cannot be obtained. Since the composite with the elastomer becomes hard and the flow of the composite is poor during hot pressing, the high-frequency heating element 3 having a uniform film thickness cannot be obtained, and the film of the high-frequency heating element 3 becomes hard. When the mechanical shock is reduced and the fall or the cooling is repeated, the high-frequency heating element 3 may be damaged. Therefore, in order to ensure excellent temperature rise performance, durability, and reliability, it is desirable that the content of the high-frequency absorbing material 5 be in the range of 20 to 60%.

(Embodiment 2)
FIG. 4 is a schematic diagram showing the structure of the particles of the high-frequency absorbing material used for the high-frequency heating element 3 in the second embodiment of the present invention.

  In the figure, a structure is shown in which a coating layer 27 is formed by treating the surface of the particles 26 of the high-frequency absorbing material with a coating agent whose outer surface layer is hydrophobic.

  Examples of the coating agent used for the coating layer 27 having hydrophobicity include higher fatty acids, organic titanium compounds, and organic silicon compounds. From the viewpoint of heat resistance, organic titanium compounds and organic silicon compounds are desirable.

  By adopting a configuration in which a coating layer 27 having a hydrophobic outer surface is formed on the surface of the particles 26 of the high frequency absorbing material, the kneadability with the elastomer 6 is improved, and the particles 26 of the high frequency absorbing material are placed in the elastomer 6. It can be uniformly dispersed.

  Thereby, the heat generating surface of the high-frequency heating element 3 can have a uniform temperature distribution, and when applied to the cooking utensil 1 for a high-frequency heating device, the object to be heated can be uniformly burnt.

  Further, since the particles 26 of the high-frequency absorbing material are uniformly dispersed in the elastomer 6, flexibility can be obtained in these composites, and when they are bonded to the heated object placing tray 2 by a hot press, The flowability of the composite is improved, the film thickness can be uniform, and the heat generation characteristics can be stabilized.

  Furthermore, the high-frequency absorbing material 26 can be filled with high density, the workability of kneading the high-frequency absorbing material 26 and the elastomer 6 is improved, and the high-frequency heating element 3 with stable quality can be obtained.

  Further, by forming the coating layer 27 on the particles 26 of the high frequency absorbing material, the coating layer 27 blocks oxygen diffusion even when exposed to a high temperature environment in the air, and the particles of the high frequency absorbing material have a crystal structure due to oxidation. Can be suppressed, and the durability can be further improved.

  The covering layer 27 is desirably coated on the particles of the high-frequency absorbing material in advance, but the effect can be exhibited even if it is added simultaneously when the high-frequency absorbing material and the elastomer are kneaded.

  As described above, since the high-frequency heating element of the present invention has excellent temperature rise performance, it can be applied not only as a heating element for cooking appliances but also as an industrial dryer or heating machine. Since it has excellent absorption performance, it can be applied as a radio wave sealing device with a cooling device.

Sectional drawing of the cooking utensil for high frequency heating appliances which affixed the high frequency heating element in Embodiment 1 of this invention Schematic diagram showing the structure of the high-frequency heating element according to Embodiment 1 of the present invention. Sectional drawing of the high frequency heating cooking appliance with which the cooking appliance for high frequency heating equipment of this invention is mounted The schematic diagram which shows the structure of the particle | grains of the high frequency absorption material used for the high frequency heat generating body in Embodiment 2 of this invention The perspective view of the to-be-heated material mounting tray with which the conventional high frequency heating element was stuck Partial sectional view of a conventional dish to be heated Schematic diagram showing the structure of a conventional high-frequency heating element

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooking utensil for high frequency heating equipment 2 Heated object mounting dish 3 High frequency heating element 5 High frequency absorption material 6 Elastomer 26 Particles of high frequency absorption material 27 Coating layer

Claims (11)

A high-frequency heating element comprising a high-frequency absorbing material having a needle-like particle shape having no phase transition at a temperature of 400 ° C. or lower. The high-frequency heating element according to claim 1, wherein the high-frequency heating element is composed of a composite of at least one kind of high-frequency absorption material having a needle shape and at least one kind of elastomer. The high-frequency heating material according to claim 1, wherein the high-frequency absorption material includes ceramic whiskers or fibers. The ceramic whisker or fiber includes at least one of a ceramic material containing zinc oxide, silicon carbide, a metal thin film layer, and a ceramic material containing silicon and titanium or zirconium, carbon and oxygen as a main component. High frequency heating element. The high-frequency heating element according to any one of claims 1 to 4, wherein a coating layer having a hydrophobic outer surface is formed on the surface of the particles of the high-frequency absorbing material. The high-frequency heating element according to any one of claims 1 to 5, wherein the elastomer includes silicon rubber or fluorine rubber. The high-frequency heating element according to any one of claims 1 to 6, wherein the content of the high-frequency absorbing material is 20 to 60% by volume. On a part of the surface on which the object to be heated of the object to be heated is not placed and a metal object to be heated on which the coating layer containing an organic polymer is placed. A cooking utensil for a high-frequency overheating device comprising the high-frequency heating element according to any one of claims 1 to 7. The cooking utensil for a high-frequency heating device according to claim 8, wherein an area of the high-frequency heating element provided on the metal heated object placing tray is 0.1 m ² or less. The cooking utensil for a high-frequency heating device according to claim 8 or 9, wherein the film thickness of the high-frequency heating element provided on the metal heated object mounting tray is 0.5 to 2 mm. A high-frequency heating cooker comprising the cooking utensil for high-frequency heating equipment according to any one of claims 8 to 10.