JPH03226962A - Far infrared radiator - Google Patents

Abstract

PURPOSE:To efficiently radiate far infrared rays using microwaves by integrating a material which generates heat by means of absorption of microwaves and a material radiating far infrared rays into a far infrared radiator. CONSTITUTION:A material which generates heat by means of absorption of microwaves and a material radiating far infrared rays are assembled and integrated together. The far infrared ray radiator has structure e.g. such that a material A which generates heat by means of absorption of microwaves and a material B radiating far infrared rays are uniformly mixed and molded or structure whose center portion is formed of the material A which generates heat by means of absorption of microwaves and in which the material B radiating far infrared rays is disposed at its outer peripheral portion. Thus the absorbing, heat-generating material in the far infrared radiator efficiently absorbs microwaves and the microwaves are converted into heat so that far infrared radiation is efficiently carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a far-infrared radiator used for heating, etc., and particularly to a far-infrared radiator used in combination with microwave heating.

(Prior Art) Far-infrared heating is a heating method that utilizes radiation, which causes less energy loss due to intermediate media, among the five forms of heat propagation: convection, conduction, and radiation. For this reason, the far-infrared heating method has been judged to have a high energy-saving effect, and has come to be widely used in consumer and industrial applications for drying and heating purposes. Recently, they have been touted not only for their use in heating and drying in a wide range of industrial fields and for heating in daily life, but also for their biological effects and improving the taste of foods.

In the conventional far-infrared heating method for heating and drying, for example, Japanese Patent Application Laid-Open No. 48-4625G and Japanese Patent Application Laid-open No. 491
No. 11241, JP-A-50-108658, JP-A-5
As disclosed in Japanese Patent No. 0-144944, etc., in both cases, the electric resistance heating element is made to generate heat by supplying electricity, and this heat is transmitted to a far-infrared radiator that is in contact with or in the vicinity of the heating element. It was said that infrared rays were emitted.

In heating and drying by far-infrared radiation from a far-infrared radiator, far-infrared rays are irradiated only from the surface of the object to be heated or dried to a very small area inside the object, and from the standpoint of mere heating and drying. , not efficient. Therefore, ideas have been devised to combine this with microwave heating, which heats objects internally and is said to be highly energy efficient. However, even in heating and drying using microwaves and far infrared rays in combination, when conventional far infrared rays are used, it is necessary to supply electrical energy to the far infrared rays. For this reason, the structure of the heating/drying device becomes complicated, and in long-term use, the far-infrared radiation function may be lost due to breakage of the electrical resistance heating element, etc.

(Problems to be Solved by the Invention) The present inventors have completed the present invention as a result of diligent research in view of the problems of the existing far-infrared radiators described above, and the purpose thereof is to The object of the present invention is to provide a novel far-infrared radiator that uses microwaves as an energy source for far-infrared radiation instead of using direct electrical energy. Another object is to provide a far-infrared radiator that has high reliability even for long-term use. Further objects and advantages of the present invention will become apparent from the following description.

(Means for solving the problem) The above purpose is to integrate a material that absorbs microwaves and generates heat with a material that emits far infrared rays. 3- Absorbs microwaves and emits infrared rays while generating heat. This is achieved by a far-infrared radiator characterized by the following.

There are many possible materials that can be used in the present invention to generate heat by absorbing microwaves, but zinc oxide and barium titanate are preferred, and silicon carbide is particularly preferred in terms of microwave absorption response. , tin oxide.

Furthermore, examples of materials that emit far-infrared rays include zirconia, titania, aluminum titanate, and silicon nitride. Among these suitable materials, zirconia and alumina provide a radiator with high strength, while cordierite efficiently emits radiation only in the far infrared region, and has the feature of providing a radiator with high impact resistance. . Furthermore, when aluminum titanate is used as a material that emits far infrared rays, a radiator with excellent heat resistance can be obtained, and when β-spodumene is used, a radiator with even better heat resistance than aluminum titanate can be obtained. It has the advantage of providing

Furthermore, when transition metal oxides are used in combination with cordierite or β-spodumene, they emit a wide range of radiation, not only in the far infrared but also in the near infrared, and silicon nitride, alone, emits a wide range of radiation from the near infrared to the far infrared. This has the advantage that a radiator with large radiant energy can be obtained.

The material that generates heat by absorbing microwaves and the material that emits far infrared rays are combined and integrated, and the following structure is preferable.

As shown in Figure 1, it absorbs microwaves.As shown in Figure 2, the center part is made of a material (4) that generates heat by absorbing microwaves, and the outer part is made of a material (6) that emits far infrared rays. A structure with

The material that generates heat by absorbing microwaves (4) and the material that emits far infrared rays) overlap in layers, or the ratio gradually increases from the front to the back as shown in Figure 5. The structure that is changing.

As shown in Figure 4, the structure is shaped into a striped pattern to absorb microwaves.

Furthermore, as shown in Fig. 5, a material (4) that generates heat by absorbing microwaves is molded, and a material (6) that easily emits far infrared rays is glazed on its surface by OVD.

Structure coated with thermal spraying, etc.

Further, in the above structure, even more excellent effects were obtained when at least a portion of the far-infrared radiator was formed with a porous structure or at least a portion with a rough surface structure.

Furthermore, in the far-infrared radiator of the present invention, the composition ratio of the material that absorbs microwaves and generates heat affects the overall calorific value, and therefore also affects the far-infrared radiation characteristics of the far-infrared radiator. In order to find out the optimal mixing ratio of the material that absorbs microwaves and generates heat for the far-infrared radiator in the present invention, silicon carbide was used as the material that absorbs microwaves and generates heat, and it was mixed with alumina in various ratios. - Create a sintered body, and microwave (transmission frequency 2.45
GHz, transmission output 500 W) for 1 minute, the state of heat generation was investigated. To create a sintered body, raw material powder at a predetermined mixing ratio is made into granules using a PVA binder, and then 1 t//
It was obtained by press molding with a mold at a pressure of cm' and then firing at 1800°C in a non-oxidizing atmosphere. However, silicon carbide is 5
In the case of 0wt% or more, the sintering did not work well, so the molded body after mold press molding was impregnated with an inorganic binder (aluminum hydroxychloride), dried, and then fired at 800°C in a non-oxidizing atmosphere. Obtained. The experimental results are shown in the 6th
As shown in the figure. As can be seen from the figure, the silicon carbide content is 10
At a silicon carbide content of 20 wt% or more, sufficient heat generation was observed, and more preferably, at a silicon carbide content of 20 wt% or more, even more sufficient heat generation was observed, and it was determined that the silicon carbide content was applicable to far-infrared radiators. An attempt was made to measure the surface temperature of the sintered body immediately after microwave irradiation using a surface thermometer, but the temperature dropped rapidly when the microwave irradiation was stopped, resulting in a slightly lower measured value.

Similar experiments were conducted for zinc oxide, tin oxide, and barium titanate (=7), and almost the same results were obtained.

(Effects of the Invention) According to the present invention, the material in the far-infrared radiator that absorbs and generates heat efficiently absorbs microwaves, converts the microwaves into heat, and efficiently radiates far-infrared rays.

The present invention will be specifically explained below using examples.

Example 1 Silicon carbide powder (average particle size 0.6pm) and alumina powder (0.8wt% MgO including average particle size 0.6.am1)
were mixed in a weight ratio of 5=7 to form P as a binder.
After fluidized bed granulation using VA, the granules were sized using a 60-mesh sieve to obtain raw material granules A.

(a) After adding 46 vol of polystyrene beads (average particle size 2.5 pm) to raw material granules A and mixing thoroughly, It/cm! A green body was obtained by press molding using a mold. The obtained green body was heated at 1800 °C in a non-oxidizing atmosphere.
It was fired at ℃ to obtain a porous sintered body. When the porosity was measured using the Archimedes method, it was found to be 75 vol.

(b) After press-molding the raw material granules A with a mold at it/cm2, firing at 1800'O in a non-oxidizing atmosphere,
A sintered body was obtained. When the porosity was measured, it was 3°vo1%
Met.

(c) It/cm of raw material granule A! After press-molding with a mold, the material was degreased in the air to obtain a green body. The obtained green body was hot-press sintered in vacuum at 1800"0 20 MPa to obtain a dense sintered body with a porosity of 3%.

The obtained sintered bodies (a) to (c) are 5 cm wide and 6 cm long.
After molding to a thickness of 0.5 cm and irradiating it with microwaves (oscillation frequency 2.45 GHz, high frequency output 500 W) for 1 minute, the temperature was measured with a surface temperature needle.
The temperature was 120''C for the porous sintered body of ), 110°C for the sintered body of (b), and 106°C for the dense sintered body of (C).

Comparative example 1 O, S containing alumina powder (average particle size 0.f+) 1ms
After granulation in a 9-year fluidized bed using PTA (wt% MgO) as a binder, the granules were sized using a 60-mesh sieve to obtain alumina granules. Alumina granules were press-molded with a mold at 1 t/emu, and then fired at 1800° C. in a non-oxidizing atmosphere to obtain a sintered body. When the porosity was measured, it was 1
It was 0vo1%.

The obtained alumina sintered body was sized to have a width of 6 cm, a length of 8 cm, and a thickness of 0.5 cm.
After molding to 5 cm, microwave (transmission frequency 2.46
When the temperature was measured with a surface thermometer after being irradiated with GHz 1 high frequency power (60 GW) for 1 minute, it was 30°C, which was almost unchanged from before the microwave irradiation.

Example 2 Tin oxide and magnesium hydroxide were mixed at a weight ratio of 1=3 and calcined in the atmosphere at 700°C, then crushed and sized (6
Mixed granules of tin oxide and magnesium oxide were obtained. After press-molding the obtained mixed granules with a mold, the mixture was placed in the atmosphere for 16 seconds. a Sintered at 0°C. The obtained sintered body was molded to a width of 5 cm, a length of 5 cm, and a thickness of 0.6 cm to obtain a microwave absorption heating plate.

10- Cordierite (average particle diameter: 1.am), iron oxide (average particle diameter: 0.57 m) and manganese oxide (average particle diameter: 0.5/um) in a weight ratio of 5:3:2 mixed with. Furthermore, after adding 50 wt% of sawdust and mixing thoroughly, the sintered body was press-molded with a mold and fired at 1200°C in the atmosphere. I got a body.

The microwave absorbing heating plate thus obtained and the porous sintered body were bonded together with an inorganic binder to obtain a far-infrared radiator.

The obtained far-infrared radiator is exposed to microwaves (wave number 2.
When the temperature was measured with a surface thermometer after being irradiated with 46 GHz (1 high frequency output 50 GW) for 1 minute, it was 100°C.
Met.

Comparative Example 2 Cordierite (average particle size: 1 μm), iron oxide (average particle size -0.67 m), and manganese oxide (average particle size: 0.5 μm) were mixed in a weight ratio of 6:3:2. Mixed. Further, 50 wt % of sawdust was added and thoroughly mixed, followed by press molding with a die and firing at 1200° C. in the atmosphere to obtain a porous sintered body. The obtained sintered body is 5 cm wide and 6 cm long.
It was molded to a thickness of 0.6 cm.

Microwave (oscillation frequency 2,450.H2, high frequency output 500W) was applied to the porous sintered body thus obtained.
The temperature after irradiation for one minute was measured with a surface thermometer and found to be 50°C.

Example 5 Mixing 3 parts of barium titanate with 7 parts of clay, 750 ml after molding
It was fired at °C to obtain an unglazed disk with a diameter of 15 cm and a thickness of 1 cm. An equimolar composition of silicon nitride was sprayed onto the entire surface of the resulting unglazed disk.

The unglazed disk thus obtained was irradiated with microwaves (oscillation frequency 2.46 GHz, high frequency output solow) for 1 minute, and the temperature was then measured using a surface thermometer.
The temperature was 200°C.

Comparative Example 3 Mixing 3 parts of barium titanate with 7 parts of clay, 750 ml after molding
An unglazed disk with a diameter of 15 cm and a thickness of 1 crn was obtained.

The unglazed disc thus obtained was irradiated with microwaves (transmission frequency 2.415 GHz, high frequency output 500 W) for 1 minute, and the temperature was then measured using a surface thermometer.
It was 85°C.

Example 4 Using the (a) microwave-absorbing sintered body of Example 1, the microwave-absorbing sintered body was placed over frozen gratin in a household microwave oven (transmission frequency 2.450 Hz, 1 high frequency output 500 W). When irradiated with microwaves for 8 minutes, not only the inside of the gratin was heated, but also the surface of the gratin was moderately burnt.

Comparative Example 4 When frozen gratin was irradiated with microwaves for 8 minutes in a household microwave oven (transmission frequency 2.46 GHz, high frequency output 50 GW), the inside of the gratin was heated, but the surface of the gratin was not burnt at all. I couldn't admit where I was.

(Effect of the invention) 15 Example 5 7 parts of zinc oxide powder (average particle size 20 μm) was mixed with 3 parts of β-spodumene powder (average particle size 50 fim),
Silica sol (Snowtex-X) is used as an inorganic binder.
Knead while gradually adding L. (manufactured by Yasusan Kagaku) to form a clay-like mixture. After molding this into a width of 6 cm, length of 5 cm, and thickness of 1 am, it was dried in a dryer (60°C), and then treated in an atmospheric firing oven at 1200°C for 2 hours to obtain a far-infrared radiator. Ta.

Microwave (transmission frequency 2.
After irradiation with 45 GHz, high frequency output (5 o ow) for 1 minute, the temperature was measured with a surface thermometer and found to be 120°C.

4 Comparative Example 5 β-spodumene powder (average particle size 30 mm) was added with silica sol (Snowtex) as an inorganic binder.
XL (manufactured by Yasusan Kagaku) is gradually added and kneaded to form a clay-like mixture. This was molded into a width of 6 ohm, length of 5 cm, and thickness of 1 cm, dried in a drier (6G'C), and further treated in a firing oven at 1200°C for 2 hours in an atmospheric atmosphere to obtain a fired body.

Microwave (transmission frequency 2,46GH) is applied to the obtained fired body.
The temperature after irradiation with z % high frequency output sow for 1 minute was measured with a surface thermometer and found to be 65°C.

[Brief explanation of drawings]

Figures 1 to 5 are explanatory diagrams showing the structure of the far-infrared radiator of the present invention, in which (1) represents a material that absorbs microwaves and generates heat, and () represents a material that emits far-infrared rays. . Furthermore, FIG. 6 shows a line representing the difference between the amount of silicon carbide and the surface temperature of the radiator of the far-infrared radiator of the present invention, which uses silicon carbide as a material that absorbs microwaves and alumina as a material that emits far-infrared rays. It is a diagram. Figure 5 00 20 40 IC 060 lz 03 60 80 (wt 010) 40 2° (wt'10) 00

Claims (1)

[Claims] (1) A far-infrared radiator characterized by absorbing microwaves and emitting far-infrared rays while generating heat, which is made by integrating a material that absorbs microwaves and generates heat and a material that emits far-infrared rays.