JPH08299190A - Microwave heater - Google Patents

Abstract

PURPOSE: To heat easily by irradiation of microwave by filling a heat-resistant container with a mixture of triiron tetroxide powder and other powder stable to heat. CONSTITUTION: A heat-resistant container is made of a material not deformable at a working temperature such as a heat-resistant resin with relatively high melting point, glass inorganics, etc., and such container is filled with a mixture of triiron tetroxide powder and other powder stable to heat in the hollow part thereof, e.g. made of a hollow and sheet-shaped material. As triiron tetroxide, marketed one can be used, for example, one prepared by pulverizing natural magnetic iron ore firing, iron in the air, reducing ferric oxide with hydrogen including steam, or pulverizing red heated iron on which steam is acted, etc. After a heated body is put in the container filled with the mixture of triiron tetroxide and powder stable to the heat, the body to be heated is heated effectively through the container by irradiation of microwave.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating element that generates heat by microwave irradiation. More specifically, the present invention relates to a heating element including a heat-resistant container filled with specific fine particles.

[0002]

2. Description of the Related Art Irradiation of microwaves when heating an object is widely performed, and in particular, a commercially available microwave oven is used for cooking food and drying resin.

[0003]

The method of heating using microwaves is an excellent method that can be easily heated under non-contact conditions, but in the case of heating the above-mentioned food, water contained in the food is excited. In addition, since the resin is dried by exciting the water contained in the resin, the heating is inefficient even though the water content is small, and it is difficult to heat the object to 100 ° C or higher. There is a problem.

[0004]

Means for Solving the Problems The present inventors have completed the present invention by solving the above problems and searching for an effective microwave heating element.

That is, the present invention is a microwave heating element obtained by filling a heat-resistant container with a mixture of powder of ferric tetroxide and other heat-stable powder.

The heat-resistant container used in the present invention is not particularly limited, and the material for forming the container may be a heat-resistant resin having a relatively high melting point, glass, an inorganic material or the like that does not deform at the temperature used. Any material can be used, but it is preferable to select a material resistant to thermal change. As is clear from the gist of the present invention as the shape of the container, there is no particular limitation, for example, in the form of a sheet,
It suffices to use a hollow sheet and fill the hollow portion with a mixture of a powder of ferric tetroxide described below and another heat-stable powder. The thickness of the space, the thickness of the sheet, etc. are not particularly limited, but the thickness is preferably as thin as possible so that heat can be transferred, as long as it has a strength suitable for the purpose of use of the container. Further, it is preferable that the thickness of the space is set to a preferable thickness depending on the required amount of heat generation, temperature and the like. Similarly, a box or dish-shaped object can be achieved by making it hollow.

In the present invention, commercially available ferric tetroxide can be used, and natural magnetite is finely pulverized or iron is burned in the air, iron (III) oxide.
Examples thereof include those obtained by reducing water with steam-containing hydrogen, and those obtained by finely pulverizing red hot iron with water vapor. The particle size of such ferrosoferric oxide is 1000 μm or less, preferably 0.01 to 100 μm.
Those having a size of about m are preferably used.

In the present invention, the heat-stable powder used by mixing with the above-mentioned ferrosoferric oxide is not particularly limited as long as it does not absorb or reflect microwaves. No change due to microwave irradiation,
Insulating inorganic substances or heat-resistant resin powders are preferably used, and metal oxides and heat-resistant resin particles are preferably used.

The method for mixing the two is not particularly limited, and any method can be used as long as it can be mixed well. For example, it can be achieved by putting ferric tetroxide and heat-stable powder in a container and agitating them with a rod or the like to simply mix them, or by thoroughly mixing them with a known mixing method such as a ball mill or a homogenizer. Here, ferric tetroxide does not need to be dispersed particularly uniformly.

The ratio of ferrosoferric oxide to heat-stable powder is about 100: 1 to 100: 5000 (weight ratio), usually about 100: 5 to 100: 1000 (weight ratio). As a measure of the preferable ratio, when filled in a container, 0.8 or less of the true density of ferric tetroxide, preferably 0.
It is to be filled with 5 or less. Excessive filling is not preferable because sparks may be generated by eddy current during microwave irradiation.

The object to be heated is placed in a container filled with the mixture of iron tetroxide thus obtained and heat-stable powder, and then microwave is irradiated. Microwaves can be sufficiently heated with a wavelength and energy that are commercially available as household microwave ovens, microwaves with a frequency of several gigahertz can be used, and energy of several KW / 1 Kg is sufficient. If it is a small object to be heated, put it in a commercially available microwave oven and irradiate it with microwaves for a few seconds to a few minutes.
Can be heated above ℃.

[0012]

EXAMPLES The present invention will be further described with reference to the following examples.

Example 1 20 g of triiron tetraoxide (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) and 10 g of silicon oxide powder having an average particle size of 100 μm were mixed well in a mortar, and then two polyimide sheets having a thickness of 0.1 mm were used. 0.5
A sheet for heating was prepared by filling two sheets having a space with a mm spacer interposed therebetween. Polypropylene (Mitsui Toatsu Chemical Co., Ltd. Mitsui Noblen JHH)
A sheet having a thickness of 1 mm obtained by press-molding -G) was sandwiched, placed in a microwave oven (Toshiba microwave oven ERT-540F manufactured by Toshiba), and irradiated with microwaves for 2 minutes. Take out and have a thickness of 1m
When the temperature of the polypropylene sheet of m was measured, it was 2
It was heated to 40 ° C. On the other hand, only a 1 mm-thick polypropylene sheet was placed in a microwave oven and irradiated with microwaves in the same manner, but the temperature was 28 ° C. and it was hardly heated.

Comparative Example 1 Titanium oxide (particulate titanium oxide for pigments manufactured by Fuji Titanium Industry Co., Ltd. (anatase type, average particle size 0.3 μm, brand name TA-100M)) was used in place of triiron tetraoxide. Was irradiated with microwaves for 10 minutes in the same manner as in Example 1, but the temperature of the polypropylene sheet was only 33 ° C.

Comparative Example 2 Barium titanate (manufactured by Hanai Chemical Co., Ltd.) was used instead of triiron tetraoxide.
The temperature of the polypropylene sheet was only 34.degree.

[0016]

EFFECT OF THE INVENTION By using the heating element of the present invention, various things can be easily heated by irradiating them with microwaves, which is extremely valuable industrially.

Claims (1)

[Claims] 1. A microwave heating element obtained by filling a heat-resistant container with a mixture of a powder of ferric tetroxide and other heat-stable powder.