JPS6146422B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing enamel having excellent far-infrared radiation characteristics. Conventionally, far-infrared radiators have been manufactured by firing a mixture containing zircon (Z _r O ₂・S _i O ₂ ) as a main component and oxides etc. at a porcelain-forming temperature (Japanese Patent Publication No. 47-25010). (see the publication) and one made by melting zircon and then spraying and welding it onto a metal substrate. Since the far-infrared radiator obtained by the former method is a type of porcelain, it is mechanically weak and has poor heating properties when energized, and it is impossible to manufacture long objects, and it requires the use of cold heat of over 500℃. This is undesirable in terms of lifespan as it causes cracks in the process, and it also has the disadvantage of low emissivity at wavelengths of 10 μm or more. Further, in the far-infrared radiator obtained by the latter method, the lining layer is non-uniform, and the difference in coefficient of thermal expansion from the metal substrate is large, so that peeling, cracking, etc. occur when used in cold heat, which is undesirable from the viewpoint of longevity. Furthermore,
The far-infrared radiator obtained by the latter method has characteristics such as a high thermal conductivity of the radiation layer, strong resistance to thermal shock such as cold use, and mechanical strength. The emissivity within the 50μ range is small and is insufficient for powerful far-infrared radiation. The present invention provides an enamel that is mechanically strong, has excellent heat-fast properties, does not cause peeling or cracking, maintains good emissivity over a wide range, and has far-infrared radiation characteristics that can be manufactured cheaply and easily. The purpose is to provide The above object is achieved by adding powdered zircon crystals to the enamel coating to form an enamel layer radiator. Either of these steps is acceptable, but it must be done before the metal base is glazed. In addition, powdered zircon is
The amount to be added is such that a predetermined amount remains in the structure of the enamel coating in a crystalline state. There are many types of frit compositions suitable for glazing metal substrates, and the applicability of the present invention has little to do with the frit components; it is also possible to separately incorporate zircon crystals into the enamel coating. Therefore, since the purpose is to ensure the crystalline phase of zircon, apart from the amount of zircon present, the composition of the frit or frits used and the composition of the mill additives also affect the usability of the present invention. It is clear that it has little effect on Therefore, in the present invention, the amount of zircon crystals added as a mill additive is determined so that after firing, at least a part of the added zircon remains in the crystalline state in the enamel layer on the metal base, resulting in an excellent distance. It is necessary to select one that exhibits infrared radiation properties. The reason why zircon was added as a mill additive is as follows. That is, if zircon is added directly to the raw materials that make up the frit, it will increase the viscosity of the frit, and if the amount added is too large, it will become unsuitable as an enamel frit for use on metal substrates, so zircon should be added at approximately 25% by weight.
Must be as follows. In this case, when the known raw material and zircon crystals are melted, they are kept at a high temperature for a long time, and all the zircon is converted to Z _r O ₂
and S _i O ₂ , and no crystalline zircon remains. FIG. 1 is a partially cutaway front view showing a far-infrared radiation device manufactured using the enamel of the present invention. _The heating element 3 having a
In a so-called sheathed heater, in which both ends of the heat radiator 1 are sealed with airtight materials 5, 5, the outer surface of the heat radiator 1 is degreased, pickled, and N
_i After pre-treatment of adhesion and neutralization, the base enamel 6' is glazed and fired, and then an enamel with good far-infrared radiation efficiency is applied and fired for a short time (approximately 3 minutes) to make the enamel. A layer radiator 6 is formed. The composition of the frit used for the base enamel 6' and the enamel layer radiator 6 is as follows. S _i O ₂ 36 (weight%) B _a2 O ₃ 27 N _a2 O 18 A _l2 O ₃ 7 C _a O 4 K ₂ O 4 C _a F ₂ 2 M _o O ₂ 1 N _i O 0.5 C _p O 0.5 The mill compositions of the base enamel 6' and the enamel layer radiator 6 are shown in the following table.

[Table] On the other hand, when we created a conventional example by mixing and melting the same amount of zircon in the frit as in the example and measuring the far-infrared radiant energy of these frits, we found that the example had a wider range of energy than the conventional example. The example exhibited extremely high far-infrared radiant energy over a wide range compared to the conventional example (see Fig. 2).
In addition, in FIG. 2, the vertical axis is the specific radiation energy, but S _i C is used as the object of comparison. Also, at this time, the temperature of each far-infrared radiation device is set so that the surface temperature is 500℃.As is clear from the above, even if the same amount of zircon is added, far-infrared radiation characteristics are better with mill addition. Moreover, the greater the amount of zircon crystal added, the better the far-infrared radiation characteristics. Furthermore, when the amount of zircon crystals added was less than about 30 parts by weight, far-infrared radiant energy almost equivalent to that of the conventional example was emitted. In addition, the far-infrared ray emitter of the example saturates to a constant temperature about 10 minutes after the heating element 3 starts being energized, and is excellent in rapid heating properties. In addition, the bond between the base enamel and the metal heat radiator 1 is achieved by mechanical bonding and chemical bonding, so it has excellent adhesion, and can actually be used for cooling and heating cycles (500 cycles of cooling and heating from room temperature to 600°C). No peeling, cracks, etc. were observed even after the above steps. Furthermore, in Examples, the hot water resistance seems to be improved compared to the conventional example. As described above, the present invention uses the conventional enamel layer forming process as it is, and only adds zircon in a mill, so it does not impair mass productivity and low cost, has excellent mechanical strength and rapid heating properties, and has excellent It is an enamel that has far-infrared radiation properties.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a partially cutaway front view of a far-infrared radiator, and FIG. 2 shows the far-infrared radiation characteristics of the enamel layer radiator of the present invention and the conventional enamel layer radiator. Figure shown.

Claims (1)

[Claims] 1. A fritted enamel composition suitable for glazing metal substrates is wet-pulverized to form a slip, and zircon crystals and a trace amount of molding plasticizer are added in an amount equivalent to 30 parts by weight or more based on 100 parts by weight of the frit in the slip. The slip containing the zircon crystals is mill-added, and the slip containing the zircon crystals is glazed on a metal base and fired to dissolve a part of the zircon crystals as ZrO ₂ and SiO ₂ in the enamel layer, and the remaining zircon crystals are removed. An enamel having far-infrared radiation characteristics, characterized in that the remainder of the enamel is dispersed in an enamel layer and left as a zircon crystal phase.