JP2010086757A - Heating ceramic and method of manufacturing the same, as well as heat insulating supplies - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide heating ceramic that is easily heated with a microwave oven, equipped with stable heating characteristics, a heat retaining property and safety to use, a method of manufacturing the same, as well as heat insulating supplies using the heating ceramic. <P>SOLUTION: The heating ceramic 10 used for microwave heating is formed by calcination of a ceramic material and a conductive material, and characterized by containing of conductor powder in the sintered body. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat generating ceramic, a manufacturing method thereof, and a heat retaining article, and more particularly to a heat generating ceramic that can be easily heated by a microwave oven, a manufacturing method thereof, and a heat retaining article using the heat generating ceramic.

  Conventionally, warming supplies such as hot water bottles have been used for keeping warm at bedtime. In recent years, warming supplies that can be easily warmed and used using a microwave oven instead of a hot water bottle have been provided. Many of the heat-retaining products that store heat using a microwave oven use water-absorbing gel (resin) as a heat-retaining material, and the water molecules are vibrated and heated by microwaves so that the heat-retaining property is maintained. Is formed.

Various materials have been proposed as materials that generate heat when heated by a microwave oven, and some products are configured to be heated by a microwave oven using ceramics as a heat insulating material. In addition, hot-spring products such as hot-water packs have been proposed as products using heating by a microwave oven.
JP 2007-44298 A JP 2002-369835 A Japanese Patent Laid-Open No. 11-9652 JP 2004-121731 A JP 2001-338748 A

  A heat-retaining article such as an orchid that heats the heat-retaining material using a microwave oven has the advantage that it can be easily heated and is easy to handle. Moreover, it is useful also from the point which can be used repeatedly. However, a product using gel (resin material) as a heat insulating material has a problem that the heat insulating material is overheated by a heating operation using a microwave oven and the heat insulating material sealing bag is ruptured.

  In addition, products that use ceramic as a heat insulating material can be heated by a microwave oven by adding water absorbency to the ceramic. And there is a variation that the heat insulating material is overheated, and there is a problem that a certain heat retaining property cannot be obtained.

  The present invention has been made to solve these problems, and can easily be heated using a microwave oven, has stable heating characteristics and heat retention properties, and can be used safely. Another object of the present invention is to provide a heat-retaining article using the heat-generating ceramic and its manufacturing method.

In order to achieve the above object, the present invention comprises the following arrangement.
That is, the exothermic ceramic according to the present invention is a exothermic ceramic used for microwave heating, and is formed by firing from a ceramic material and a conductive material, and a conductive powder is contained in the fired body. And
In addition, the exothermic ceramic according to the present invention is preferably one containing iron powder as the conductor powder, and more preferably one using powdered iron and aluminum as the conductive material. Used for.

The heat-retaining article according to the present invention is a heat-retaining article formed by storing a heat-retaining material heated by a microwave oven, wherein the heat-retaining material is a heat-generating ceramic used for microwave heating, and is a ceramic material. And a conductive material, and the conductive material powder is contained in the fired body.
In addition, as the heat-retaining article, the heat generating ceramic contains iron powder as the conductor powder, and the heat generating ceramic uses powdered iron and aluminum as the conductive material. Those are particularly preferably used.

Further, as a method for producing a heat generating ceramic according to the present invention, a step of mixing a ceramic material formed as a powder having clay and a firing aid and a powdery conductive material, the ceramic material, The method includes a step of forming a molded product by molding a mixture with a conductive material, and a step of firing the molded product.
Further, in the method for producing a heat generating ceramic according to the present invention, powdered iron and aluminum are used as the conductive material, and in the step of firing the molded product, the firing temperature is set to 400 ° C to 800 ° C. This is particularly effective in producing a heat-generating ceramic having excellent heat generation properties.

  The heat generating ceramic according to the present invention can be easily and efficiently heated by a microwave oven because the conductive powder is contained in the fired body, and can be suitably used as a heat insulating material for heat insulating products. . The heat-retaining article according to the present invention is provided as a product that can be easily warmed by a microwave oven and can be handled safely.

(Heat generation ceramic)
Embodiments of the configuration of the heat generating ceramic according to the present invention and the manufacturing method thereof will be described below.
FIG. 1 shows an external view of the heat generating ceramic 10. The exothermic ceramic 10 of this embodiment is formed as a spherical fired body having an outer diameter of about 5 mm. A feature of the exothermic ceramic 10 is that the conductive powder (iron powder) is contained in the fired body in an unoxidized state, so that it is efficiently heated by a microwave oven. That is.

  Clay, cordierite, petalite, alumina or the like is used for the ceramic material forming the exothermic ceramic 10. The material of the ceramic material forming the exothermic ceramic 10 is not particularly limited, and can be used by appropriately combining materials. Cordierite and petalite have high heat resistance, and even when the heat-generating ceramic 10 is fired at a low temperature, there is an advantage that it can be fired densely without cracks.

Although the heat generating ceramic 10 of the embodiment shown in FIG. 1 is fired into a spherical shape, the shape of the heat generating ceramic can be arbitrarily set, and the size of the heat generating ceramic can also be arbitrarily set.
As a form of the heat generating ceramic, for example, it can be formed into an ellipsoid, a thin plate, a polygon or the like. Moreover, even when it forms in a spherical shape, it can be formed to have an outer diameter of 5 mm or more, or can be formed to 5 mm or less. Moreover, when forming in thin plate shape, it can be set as arbitrary shapes, such as a square and a rectangle, and can be formed in the magnitude | size of several mm square or several cm square.

  Fe, Al, Au, Ag, Cu, Si, or the like is used as a conductive material added to the ceramic material. The reason why the conductive material is added to the ceramic material is to cause the heat generating ceramic to generate heat by heating the microwave by adding the conductive material to the heat generating ceramic. The conductive material added to the ceramic material is not limited to metal, and any non-metal conductive material such as Si can be used.

These conductive materials are added to the raw material as powder. The exothermic ceramic 10 is obtained by mixing a ceramic material and a conductive material and forming the mixture into a predetermined shape, for example, a spherical shape, and then firing the molded product.
When the conductive material mixed with the ceramic material is not oxidized when fired and is contained in the exothermic ceramic 10 as a conductive powder, heating by a microwave oven is effectively performed.
The exothermic ceramic 10 of the present embodiment is fired at a low firing temperature so that the conductive material added to the ceramic material is not oxidized during firing.

  When the heat generating ceramic 10 contains a conductive material, generally, the larger the amount of the conductive material, the stronger the heating action by the microwave oven. Therefore, it is preferable that the amount of the conductive material contained in the heat generating ceramic 10 is adjusted according to the heat-retaining article such as red bean so as to be suitably heated when heated in the microwave oven.

(Method for producing exothermic ceramic)
The exothermic ceramic is obtained by mixing a ceramic material and a conductive material, forming the ceramic material into a predetermined shape, and firing the molded product. Below, the manufacture example of a heat-generating ceramic is demonstrated.
As the ceramic material, clay, cordierite, pentalite or the like and a firing aid such as phosphoric acid frit are used. The reason why the firing aid is used is to lower the firing temperature when firing the exothermic ceramic. Any appropriate material other than phosphoric acid frit can be used for the firing aid.
For example, the firing temperature when firing ceramic using clay and cordierite as the ceramic material is about 1100 ° C to 1200 ° C. On the other hand, when a phosphoric acid frit is added as a baking aid and baking is performed, the baking temperature is reduced to about 600 ° C. Thus, by making the firing temperature as low as possible, the conductive material added to the ceramic material during firing can be prevented from being oxidized.

  Note that the firing temperature when firing the exothermic ceramic varies depending on the material of the ceramic material, the type of firing aid, the amount added, and the like. Accordingly, the firing temperature of the exothermic ceramic is appropriately set as a composition according to the amount and type of the ceramic material and firing aid used, and the conductive material added to the ceramic material. The firing temperature of the exothermic ceramic is preferably set as low as possible so that the exothermic ceramic is densely fired and the conductive material added to the ceramic material is not oxidized as much as possible. The firing temperature for preventing the conductive material added to the ceramic material from being oxidized as much as possible may be about 400 ° C. to 800 ° C., although it depends on the conductive material.

In this embodiment, aluminum (Al) and iron (Fe) are mainly used as the conductive material added to the ceramic material. Aluminum and iron are added as powder having a particle size of about 10 μm to 100 μm. Similarly, powder is also used for ceramic materials.
The quantity ratio (weight ratio) of the raw materials is as follows.
(Sample A)
Iron 5%, Aluminum 30%, Clay: 50%, Phosphate frit 10%, Titanium oxide 5%
(Sample B)
Iron 10%, Aluminum 60%, Clay: 15%, Petalite 10%, Phosphate frit 5%
(Sample C)
15% iron, 60% aluminum, 20% clay, 5% glass powder

These raw materials are mixed well for about 12 hours using a pot mill (step of producing a mixture).
It shape | molds, adding water as a binder to the mixed raw material powder. In order to form into a granule, a clay seed ball having a particle diameter of 1.4 mm to 1.7 mm prepared in advance is rolled into a raw material to be granulated. It can also be formed into a flat plate shape by pressing or the like (forming step).

Next, the molded product is placed in a firing furnace and fired to form a heat generating ceramic (firing step).
In the firing step, the molded article is heated to a firing temperature, for example, 600 ° C., for example, about 600 ° C. in about 4 hours after being placed in a firing furnace, maintained at 600 ° C. for 3 hours, and then gradually lowered to room temperature and fired.
None of the samples A, B, and C were sintered at a firing temperature of 500 ° C. or lower, and the conductive material was oxidized at a temperature of 650 ° C. or higher. did.

As described above, in order to efficiently heat the heat generating ceramic when the heat generating ceramic is heated by the microwave oven, it is preferable that the conductive powder contained in the heat generating ceramic is not oxidized as much as possible.
In the above embodiment, aluminum and iron are added as conductive materials because aluminum is more easily oxidized than iron, so that when exothermic ceramic is fired, iron powder is not oxidized by oxidation of aluminum. It is to do.

The reason why the addition amount of aluminum is set to about five times the addition amount of iron is that the action of suppressing the oxidation of iron powder by the action of aluminum is effective. According to experiments, even when the amount of aluminum was set to be six times or more of the amount of iron, the heat generation action of the heat generating ceramic (the action heated by the microwave oven) did not change significantly. Therefore, the addition amount of aluminum may be about 6 times or less that of iron.
In addition, even if iron is oxidized (Fe3O4), since it has electroconductivity, it is used suitably as a electrically conductive material contained in a heat-generating ceramic.

(Comparative example)
A ceramic ball using ferrite as a raw material was used as a comparative sample of the exothermic ceramic of this example.
This ceramic ball is made of clay, cordierite, and ferrite, and the ratio of raw materials (weight ratio) is 15% for clay, 38% for cordierite, and 47% for ferrite. All use powder as a raw material.
After the raw materials were mixed for 12 hours by a pot mill, a granule having an outer diameter of about 5 mm was formed using a seed of clay.
The molded product formed into a granular shape was put into a firing furnace, heated to 1130 ° C. over 7 hours, maintained at 1130 ° C. for 3 hours, and then gradually cooled to room temperature and fired.

  Comparing the above-described examples and comparative examples, in the examples, it is fired at a much lower temperature than the comparative examples, whereas in the examples, aluminum and iron powders were added as conductive materials. The comparative example is different in that ferrite (iron oxide) is added.

Table 1 shows the results of the microwave heating and the cooling test performed on the heat generating ceramic (for sample A) produced by the method of the above-described example and the ceramic ball formed by the method of the comparative example.
In the test, 500g each of the exothermic ceramic and the above ceramic balls are separately stored in a cloth bag, and the sample is put in a microwave oven (output 500W) and heated for 30 seconds. Was measured.
In the measurement, the heated sample was placed on a table, and the temperature of the bag surface (cloth) was measured using a surface thermometer. At every measurement, it was confirmed whether the warmth was actually felt.

The measurement results shown in Table 1 indicate that the exothermic ceramic of the example is heated more efficiently by using the microwave oven than the ceramic ball of the comparative example, from the measured value immediately after heating by the microwave oven.
In the test of Table 1, the measurement is stopped when the temperature of the sample reaches 35 ° C. in consideration of the heat retaining property for the human body. Comparing the elapsed time until the temperature of the sample reaches 35 ° C., it was confirmed that the ceramic ball of the comparative example has 15 minutes, while the exothermic ceramic of the example has a heat retaining property up to about 30 minutes. .

  The exothermic ceramic of the above embodiment has an effective heat retaining action when heated by a microwave oven, in the case of the exothermic ceramic of the present invention, it can be heated efficiently and can be heated in a short time. It is thought that ceramic is due to its high heat retention (heat storage). Table 2 is an experiment in which the heat-generating ceramic of the example and the ceramic ball of the comparative example were heated to the same temperature and then allowed to cool to compare the heat retention. The exothermic ceramic of the example was heated for 1.5 minutes, and the ceramic ball of the comparative example was heated for 5 minutes.

  The experimental results in Table 2 show that the temperature of the conventional ceramic ball was lowered to 35 ° C. after 20 minutes, while the temperature of the exothermic ceramic of this example was 35 minutes before the temperature was lowered to 37 ° C. The ceramic ball used as a comparative example is a product with relatively good heat retention as a ceramic by high-temperature firing, but the exothermic ceramic of this example has a lower temperature drop rate than the comparative example, and the heat retention. It can be seen that this is also excellent.

In addition, when heating a heat generating ceramic using a microwave oven, the temperature of a heat generating ceramic rises by lengthening the heating time by a microwave oven. Therefore, when using the heat generating ceramic, it is necessary to use the heating time of the microwave oven limited to a predetermined time.
Table 3 shows the results of measuring how the temperature of the exothermic ceramic changes depending on the heating time in the microwave oven.

  According to the measurement results in Table 3, the temperature of the exothermic ceramic increases as the time for heating by the microwave oven increases, but the temperature does not increase significantly after the elapse of 3 minutes. As described above, the heating temperature of the heat generating ceramic when it is heated by the microwave oven is changed by changing the kind and amount of the conductive material added to the ceramic material. Therefore, what is necessary is just to select the quantity of the electrically conductive material added to a ceramic material, and the electrically conductive material to be used according to the characteristic calculated | required by a heat insulating material. Since the ceramic material and the conductive material use powder, it is easy to adjust the amount of the conductive material added to the ceramic material, and a heat generating ceramic having appropriate characteristics can be formed according to the heat-retaining article.

(Insulation products)
The heating / cooling test described above indicates that the heat generating ceramic according to the present invention can be easily heated by a microwave oven and can be suitably used as a heat insulating material for a heat retaining article.
FIG. 2 is a view showing an example in which the heat generating ceramic according to the present invention is used for a heat-retaining product. FIG. 2A is a heat-retaining product 20 formed in a rectangular pad shape, and FIG. FIG. 2 (c) shows an example of a warming product 40 formed as a circular pad, and FIG. 2 (d) shows an example of a warming product 50 formed as an elongated shape such as a muffler.

  The warming supplies 20, 30, 40, and 50 are preferably formed by forming seams in the middle of the bag body and filling each of the pouches with the exothermic ceramic 10 so that the exothermic ceramic 10 is not biased. Depending on the application, the heat generating ceramic 10 may be stored in a part of the bag instead of storing the heat generating ceramic 10 on the entire surface of the bag. The filling amount of the exothermic ceramic 10 is appropriately adjusted according to the volume of the product.

  Table 4 shows that the heat retaining article 20 (500 g of exothermic ceramic) formed in the shape of a rectangular pad shown in FIG. The result of having measured how the surface temperature of the heat retaining article 20 changes with progress is shown.

  The measurement results in Table 4 show that the temperature of the warming product 20 immediately after being heated by the microwave oven is 63 ° C., and the temperature of the warming product 20 gradually decreases, but 40 ° C. and 70 minutes have passed after 60 minutes. It is 38 degrees Celsius with time. If it is used for foot warming in a futon, it can be used practically without problems if it can be kept warm for about 1 hour, and it can be used for heating only at bedtime.

  Table 5 shows the results of measuring the temperature change after heating the warming article 30 (filled with 500 g of exothermic ceramic) for shoulder shown in FIG. 2 (b) for 60 seconds using a microwave oven (output 500 W) Indicates.

  The measurement results shown in Table 5 indicate that the temperature of the heat retaining article 30 immediately after being heated in the microwave oven is 60 ° C., and 40 ° C. after 30 minutes. Since it is considered that the warming article 30 for shoulder use should be able to ensure the warming for about 15 to 30 minutes, the warming article using a heat generating ceramic is also preferably used for such applications.

FIG. 2 shows an example of a heat-retaining article that uses a heat-generating ceramic as a heat-retaining material. The heat-generating ceramic according to the present invention includes an ankle, a shoulder, a collar, a knee, a knee, a muffler, and a foot temperature. It can be applied to various warming supplies such as pads.
Since the heat-retaining article according to the present invention uses a heat-generating ceramic as a heat-retaining material, it is lighter than a heat-retaining article using hot water (such as a hot water bottle), and a product using hot water or a gel for keeping warm. There are various advantages such as no danger in handling, heating in a short time, and repeated use.

It is an external view of a heat generating ceramic. It is a top view of a heat retention article.

10 Exothermic ceramic 20, 30, 40, 50

Claims (9)

A heat generating ceramic used for microwave heating,
It is formed by firing from ceramic material and conductive material,
A heat generating ceramic characterized in that a conductive powder is contained in a fired body.   The heat generating ceramic according to claim 1, wherein iron powder is contained as the conductor powder.   2. The heat generating ceramic according to claim 1, wherein powdered iron and aluminum are used as the conductive material. A heat-retaining article formed by storing a heat-retaining material heated by a microwave oven,
The heat insulating material is a heat generating ceramic used for microwave heating,
It is formed by firing from ceramic material and conductive material,
A heat-retaining article characterized in that a conductive powder is contained in the fired body.   The heat-retaining article according to claim 4, wherein the exothermic ceramic contains iron powder as the conductor powder.   6. The heat-retaining article according to claim 5, wherein the heat-generating ceramic uses powdered iron and aluminum as the conductive material. A step of mixing a ceramic material formed as a powder having clay and a firing aid, and a powdery conductive material;
Forming a molded product by molding a mixture of the ceramic material and the conductive material;
And a step of firing the molded article.   The method for producing a heat-generating ceramic according to claim 7, wherein powdered iron and aluminum are used as the conductive material.   The method for producing a heat generating ceramic according to claim 7 or 8, wherein, in the step of firing the molded article, a firing temperature is set to 400 ° C to 800 ° C.

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