JPH0414880Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] Regarding a leakage radio wave prevention device that prevents radio wave leakage from a microwave oven, more specifically, it has heat resistance and humidity resistance for a short time in a high temperature and humid environment, and has moderate heat resistance. The present invention relates to a leakage radio wave prevention device for a microwave oven that has excellent flexibility.

[Conventional technology]

Conventionally, at least one of the opening rim of a microwave oven or the inner surface of the lid that comes into contact with the opening rim is provided with a synthetic resin annular sheet having approximately the same shape as the opening rim, and soft ferrite is mixed into this annular sheet. hand,
It also absorbs radio waves leaking inside the microwave. Since this leakage radio wave prevention device is fitted and fixed into a fitting groove carved into the edge of the opening of the microwave oven, it requires a certain degree of flexibility, and from this point of view, it is not suitable as a binder for mixing and dispersing soft ferrite. Rubber and nylon materials have been used.

By the way, modern microwave ovens have increased oscillation output and are equipped with oven functions and
For example, microwave ovens that are equipped with external heating means such as infrared rays, steam, and gas combustion heat sources are beginning to appear, in addition to the microwave heating of microwave ovens, which are equipped with higher-temperature external heating means. In this type of microwave oven, the amount of heat generated inside the leakage radio wave prevention device increases due to the large oscillation output, and the interior becomes hot and humid due to steam and gas combustion. In addition to flexibility, leakage prevention devices used in microwave ovens are required to have enhanced heat resistance, and are also required to have moisture resistance. For example, the maximum operating temperature for nylon-based devices, which have traditionally been used as leakage prevention devices, is approximately 180°C, for rubber-based devices, it is approximately 150°C, and for polypropylene-based devices, the maximum operating temperature is 130°C.
℃, which is the internal temperature when heating methods such as infrared rays and steam are used in the microwave.
It cannot withstand high heat of about ℃~240℃.
The use of polyphenylene sulfide as a synthetic resin that can withstand such high temperatures has been considered, but this material has the problems of being brittle and expensive, making it difficult to use. ing.

Phenol resins and epoxy resins are known as resins that can withstand relatively high temperatures although they do not have the same heat resistance as polyphenylene sulfide. Therefore, the use of these resins as binders is considered, but phenolic resins and epoxy resins are hard and inflexible, and especially become brittle when ferrite powder is dispersed, so they are not suitable for leakage radio wave prevention equipment. When used as a binder, it is necessary to add a softener. however,
In order to ensure sufficient flexibility for these resins to be used as leakage prevention equipment, it is necessary to add a large amount of softener, and when a large amount of softener is added, flexibility can be ensured, but heat resistance is reduced. This results in a problem that is difficult to solve, such that it can no longer be used as a leakage prevention device used in high-temperature environments.

In particular, such ovens and microwave ovens need to have short-term heat resistance, especially heat resistance at about 230°C for 30 to 60 minutes. It is required to achieve the above heat resistance while maintaining the flexibility necessary to prevent cracking and chipping.

The present invention was developed in view of the current situation, and has short-term heat resistance and short-term humidity resistance that can withstand high-temperature air or high-temperature and humid environments at least during cooking time, and is necessary as a device to prevent leakage of radio waves. The present invention aims to provide a leakage radio wave prevention device that also has excellent flexibility.

[Means for solving problems]

In order to achieve the object of the present invention, the present invention provides a leakage radio wave preventer for microwave ovens made of polymethylpentene mixed and dispersed with ferrite and/or metal powder, carbon, and a small amount of softener. do.

[Effect]

As described above, the leakage radio wave prevention device for a microwave oven according to the present invention uses polymethylpentene as a binder together with a small amount of a softening agent. Polymethylpentene is already known as a resin with excellent heat resistance, but although polymethylpentene itself is relatively soft compared to other resins, it is still not flexible enough to be used as a leakage prevention device. Mixing and dispersing ferrite powder etc. tends to make it brittle, and simply mixing and dispersing ferrite powder etc. into such polymethylpentene does not provide the flexibility and mechanical strength necessary for a leakage radio wave prevention device. The purpose of adding a small amount of softener is to adjust the softness of the entire material after mixing and dispersing ferrite powder, etc. However, unlike phenol resins and epoxy resins, polymethylpentene does not require a small amount of softener. Since the degree of flexibility can be increased by adding , there is little decrease in heat resistance, and sufficient heat resistance can be ensured for use in environments of high heat and humidity. Furthermore, it can withstand the heat generated inside the leakage radio wave preventer due to high-output microwaves, and the leakage radio wave preventer will not be damaged by melting.

Since this leakage radio wave preventer is flexible, it is easy to fit and fix into the installation location of the microwave oven, and it can also be damaged even if shock is applied to the leakage radio wave preventer due to opening and closing of the door during use. There's nothing to do.

〔Example〕

The details of the present invention will be explained based on further illustrated embodiments. As shown in FIG. 1, the leakage radio wave prevention device for a microwave oven according to the present invention is, for example, an inner surface of a lid 3 or an opening of the main body that opens and closes by abutting against an opening rim 2 of a container body 1 of a microwave oven in FIG. A metal plate is used on at least one of the edges 2 as an annular sheet 4 whose entire shape is substantially the same as the opening edge 2, and as shown in FIG. It is used as a plate 7 having a large number of ventilating pores 6 provided on the surface of the plate 5. At least, the leakage radio wave prevention device according to the present invention not only irradiates microwaves such as an oven microwave oven, but also has a separate external heating means such as infrared rays, high temperature steam, and gas combustion, and uses these to heat the object to be heated. The present invention is intended to provide heat resistance and moisture resistance to each part of the microwave oven that is heated and comes into contact with high-temperature, humid air, and also has leakage radio wave absorption or reflection effects. The leakage radio wave preventer used here can be obtained by molding polymethylpentene mixed and dispersed with ferrite and/or metal powder, carbon, and a softener. As the ferrite, manganese zinc ferrite, nickel zinc ferrite, manganese magnesium ferrite, magnetite and other soft ferrites, and a mixture of these with carbon or carbonyl iron powder can be used alone or in combination. This ferrite has the effect of absorbing leakage radio waves, so by mixing it into the leakage radio wave preventer made of polymethylpentene, it absorbs and attenuates the leakage radio waves. Furthermore, when metal powder is used instead of ferrite, although there is no absorption effect on leaked radio waves, a reflection effect can be expected. The metal powder may be pure metal powder, such as powder of aluminum, copper, iron, brass, etc., or oxides thereof, such as magnetite, α-iron oxide, etc. It is also considered to use appropriate amounts of ferrite and metal powder together. On the other hand, hard ferrite (mixture with rubber or plastic, sintered ferrite alone) such as barium ferrite and strontium ferrite, which can be magnetized, is used in combination with the leakage radio wave prevention device. Next, polymethylpentene has a melting point of about 240°C, and the short-term heat resistance required for ovens, microwaves, etc. is 30°C at about 220°C to 240°C.
Since the heating time is approximately 60 minutes to 60 minutes, it is possible to obtain heat resistance for a short time by manufacturing a device for preventing leakage radio waves using this polymethylpentene. Moreover, this polymethylpentene not only has high temperature resistance as described above, but also has favorable moisture resistance. For example, in terms of heat resistance, when a nylon-based material is used as a leakage radio wave prevention device, it can withstand a certain degree of high temperature, for example, around 180°C, but at room temperature and humidity, 6-nylon has a moisture content of about 2%. , it swells due to this moisture content, and even if it is used as a leakage radio wave prevention device, it has the disadvantage that the clearance is closed at a portion where a predetermined clearance is required. For example, in microwave ovens, the dimensions of the chiyoke groove used with a leakage radio wave preventer to effectively prevent radio wave leakage must be strictly controlled, but When the leakage radio wave prevention device swells, this predetermined clearance cannot be maintained, and radio wave leakage may increase.

Since polymethylpentene has excellent moisture resistance, it does not swell and can maintain a predetermined dimensional clearance. In addition, since it is not as expensive as polyphenylene sulfide, it can be used as a leakage radio wave prevention device due to its heat resistance, moisture resistance, and moldability. In addition, since polymethylpentene with a softener added has flexibility, it can be used as flexibility when attaching a molded leakage prevention device to the fixed part, and can also be used to reduce stress caused by heat shrinkage. This can be used to prevent deformation or restore deformed objects.

Softeners are used to maintain the softness of the entire material when ferrite, metal powder, and carbon are mixed into polymethylpentene, and softeners such as silane coupling agents are generally used. . Polymethylpentene requires only the addition of a small amount of softener to obtain the flexibility necessary for use as a leakage radio wave prevention device, and because the amount of softener added is small, there is less decrease in heat resistance. It is possible to provide a leakage radio wave prevention device that takes advantage of its own excellent heat resistance.

The blending ratio of ferrite and/or metal powder, carbon, and polymethylpentene is, for example, ferrite and polymethylpentene, the former being 20 to 85% by weight and the latter being 80 to 15% by weight, and the mixture is dispersed and molded. It is desirable to do so. As mentioned above, a small amount of the softener is sufficient, and it is required to mix the softener in a ratio of 0.05 to 0.20 parts by weight per 1 part by weight of polymethylpentene. In addition, if the lower limit of ferrite is 20% by weight or less and polymethylpentene is 80% by weight or more, the radio wave absorption effect as a leakage radio wave prevention device will decrease and the value as a product will be reduced, so it will be excluded. Polymethylpentene of more than 15% by weight and less than 15% by weight of polymethylpentene are excluded because moldability is poor and it is not possible to obtain a leakage radio wave preventive device with the desired strength.

As described above, the microwave oven leakage radio wave prevention device according to the present invention uses polymethylpentene as a base material mixed with ferrite and/or metal powder, and carbon, so it is On the other hand, it has short-term heat resistance and moisture resistance,
Furthermore, since a softener is added, flexibility can also be exhibited. Moreover, since only a small amount of softener is required, the excellent heat resistance inherent to polymethylpentene will not deteriorate, making it suitable for use in microwave ovens with high-temperature, humid air, such as oven microwave ovens, which have recently become commercially available. It can be used as a leakage radio wave prevention device.

Next, as the leakage radio wave prevention device according to the present invention, a ring-shaped sheet 4 as shown in FIG. By further installing a plate 7 made of polymethylpentene according to the present invention and mixed and dispersed with ferrite and/or metal powder, carbon, and a softener on the inner surface of the metal plate 5 provided, the plate 7 prevents leakage of radio waves. Some of the steam or high-temperature gas in the container body 1 is absorbed into the punched holes 8 of the plate 7 and the metal plate 5.
It is discharged through Note that FIGS. 4 and 5 show other examples of the annular sheet 4 shown in FIG. are mixed and dispersed, the magnetized hard ferrite part 9 is used to magnetize the inner surface of the lid 3, and the soft ferrite part 10 is used to absorb leakage radio waves. The illustrated example uses a magnetized hard ferrite part 9 on the inner periphery, a soft ferrite part 10 on the outer periphery, and has a thickness equal to that of the hard ferrite part 9.
By making the lid thinner, the lid 3 becomes closer to the container body 1.
The surface of the soft ferrite portion 10, which is magnetically attached to the opening edge 2 and has a large height, is brought into contact with the inner surface of the lid 3, thereby absorbing leakage radio waves while providing a tight seal. Also, what is shown in Fig. 5 is ferrite and/or
Alternatively, it is molded from polymethylpentene mixed and dispersed with metal powder, carbon, and a softener, and a magnet 11 is embedded in a part or the entire circumference of the molded material, and the lid body 3 is magnetically attached to the opening rim 2 of the container body of the microwave oven. The inner surface of the lid 3 and the soft ferrite portion 1 which is the surface of the absorbent device
0 surface to prevent absorption of leakage radio waves.

[Effect of idea]

As described above, the microwave oven leakage radio wave prevention device according to the present invention is molded from polymethylpentene mixed and dispersed with ferrite and/or metal powder, carbon, and a softener, so if it is attached to each part of the microwave oven, It goes without saying that it can absorb or reflect leakage radio waves, and this leakage radio wave prevention device uses nylon-based synthetic resin or polypropylene-based synthetic resin as a binder.
Furthermore, it is possible to achieve significantly superior heat resistance compared to conventional leakage radio wave prevention devices using rubber-based materials. Moreover, polymethylpentene can exhibit the flexibility necessary for use as a leakage radio wave prevention device by adding a small amount of softener, so there is little deterioration in heat resistance, and polymethylpentene's original excellent heat resistance can be utilized.

Therefore, even when used in a high-output microwave oven, it will not be melted by the heat generated inside the leakage radio wave prevention device, and it can also be used with infrared rays, steam, and even gas combustion heat sources, which have become popular in recent years. The present invention can also be applied to a microwave oven that has an external heating means and that has a high temperature and humidity inside. Furthermore, since this leakage radio wave prevention device has excellent heat resistance and moisture resistance, there are problems such as when the leakage radio wave prevention device swells during use and closes off areas where a specified clearance should be provided. There is no generation of radio wave leakage, and an excellent radio wave leakage prevention effect can be exhibited.

Furthermore, this leakage radio wave prevention tool has excellent flexibility, so it can be easily installed on the fixed part of the microwave oven.
In addition, it prevents deformation due to stress generated during heat shrinkage, makes it easier to restore after deformation, and is durable enough to not be damaged by shocks caused by door opening and closing operations during use. An excellent device for preventing leakage radio waves can be provided.

[Brief explanation of drawings]

Figure 1 shows the first leakage radio wave prevention device according to the present invention.
Figure 2 is an explanatory perspective view of the absorber attached to the rim of the microwave oven opening, Figure 3 is a perspective view of the absorber attached to the rim of the microwave oven opening, and Figure 3 is a perspective view of the absorber attached to the edge of the microwave oven opening. 4 is a cross-sectional explanatory diagram of another modified absorber of the first embodiment, and FIG. 5 is a cross-sectional explanatory diagram showing yet another modified example of the absorber. It is. DESCRIPTION OF SYMBOLS 1... Container body, 2... Opening rim, 3... Lid, 4... Annular sheet, 5... Metal plate, 6... Pore, 7... Plate, 8... Punch hole, 9... ...Hard ferrite part, 10... Soft ferrite part, 11... Magnet.

Claims (1)

[Claims for Utility Model Registration] 1. A leakage radio wave preventer for microwave ovens made of polymethylpentene mixed and dispersed with ferrite and/or metal powder, carbon, and a small amount of softener. 2. A leakage radio wave prevention device for a microwave oven as set forth in claim 1 of the utility model registration claim, which uses soft ferrite or hard ferrite as the ferrite. 3. A leakage radio wave preventer for a microwave oven according to claim 1 or 2 of the utility model registration claim, which uses pure metal powder and/or an oxide of pure metal powder as the metal powder. 4 Utility model registration claim 1 or 2 utilizing a mixture of ferrite and polymethylpentene at a ratio of 20 to 85% by weight to 80 to 15% by weight
A leakage radio wave prevention device for a microwave oven as described in item 1 or 3. 5. The leakage radio wave preventer for a microwave oven according to claim 1, wherein the ratio of polymethylpentene to softener is 1 part by weight to 0.05 to 0.20 parts by weight. 6 An annular sheet made of polymethylpentene that is attached to at least one of the rim of the opening of the microwave oven or the inner surface of the lid that comes into contact with the rim of the opening, the entirety of which is approximately the same shape as the rim of the opening, and the inner periphery of this annular sheet member A leakage radio wave preventer for a microwave oven according to claim 1, which utilizes hard ferrite dispersed in one of the outer circumferential portion and soft ferrite dispersed in the other. 7 Attached to at least one of the rim of the opening of the microwave oven or the inner surface of the lid that comes into contact with the rim of the opening, is an annular sheet made of polymethylpentene whose entire shape is approximately the same as the rim of the opening, and is attached to the appropriate position of this annular sheet member. A leakage radio wave preventer for a microwave oven according to claim 1, which is comprised of a buried magnet that magnetically attaches the rim of the main body and the lid. 8. A leakage radio wave preventer for a microwave oven according to claim 1, which is a plate having a large number of ventilation holes and is used as an interior material attached to the inner surface of the main body.