JPS635339B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing an enamel heating element for far-infrared radiation. Conventionally, there have been the following methods for producing far-infrared radiant heating elements, which have been used for drying paint, removing water from wood, preheating and drying for manufacturing electronic parts, and the like. Thermal spraying method of melting zirconia ceramic and spraying it onto a metal base to form a coating.First, a strong adhesive underglaze is applied to the metal base, enamel baking is performed, and then far-infrared emissivity is applied. big
There was a double-baking method in which a top glaze containing ZrO ₂ , SiO ₂ and other oxides was further applied on top of the glaze, and the enamel was fired. However, the ceramic thermal spraying method described above has the disadvantage that the ceramic coating is likely to peel off from the metal substrate, resulting in cracks, and that the manufacturing cost is high. In addition, the double enamel firing method requires two enamel firings, so the manufacturing process is complicated.
The drawback was that it also increased costs. In addition, as mentioned above, high-cost ceramics and
In order to eliminate the trouble of multiple firings, as a method to easily obtain the desired object with one firing, the component ratio of the frit, which is the base of the enamel glaze, is determined by weight ratio from SiO ₂ 35 to 35.
36%, _B2O3 26-27 _% , _Na2O18-19 % _{, Al2O36}
~7%, CaO4~6%, _K2O3 ~4%, CaF2 ₁ ~3
%, _MnO2 1~2%, NiO0.3~0.6%, CoO0.3~
0.6%, and the mill additives to be added to 100 parts of this frit are 40 parts or more of ZrO ₂ /SiO ₂ , 4 to 7 parts of clay,
Stopper 0.2-0.5 parts, _MnO2 , _Cu2O , _FeO3 ,
A slurry-like mixture of 2 to 5 parts of one or more of Al ₂ O ₃ , CoO, NiO, Cr ₂ O ₃ , and Fe ₃ O ₄ and 45 to 55 parts of water was applied directly to a metal substrate. and 800℃~850
There is a method of obtaining a far-infrared radiating heating element by performing enamel firing only once at a predetermined temperature of .degree. C. (see Japanese Patent Laid-Open No. 57-56348). The present invention replaces 40 parts or more of ZrO ₂ ·SiO ₂ in the mill additive with potassium feldspar (K ₂ O · Al ₂ O ₃ · 6SiO ₂ ) and petalite (Li ₂ O · Al ₂ O ₃ · 8SiO ₂ ). , one or more types of colemanite (2CaO.3B ₂ O ₃ .5H ₂ O) or 50 parts or more of these and ZrO.SiO ₂ are added, and will be described below based on Examples. Table 1 shows the component ratio of the frit, and Table 2 shows the component ratio of the enamel glaze. Table 1 Component name Mixture (weight ratio) SiO ₂ 35-36% B ₂ O ₃ 26-27 Na ₂ O 18-19 Al ₂ O ₃ 6-7 CaO 4-6 K ₂ O 3-4 CaF ₂ 1- 3 MnO ₂ 1~2 NiO 0.3~0.6 CoO 0.3~0.6

[Table] The frit shown in Table 1 and the mill additive shown in Table 2 are made into a slurry and applied to a metal substrate.
If enamel firing is carried out at 850℃, potassium feldspar, petalite, colemanite, or any of these will be present in the enamel layer.
Since ZrO ₂ and SiO ₂ are dispersed heterogeneously, ZrO ₂ and
JP-A-57-56348 in which only SiO ₂ is dispersed heterogeneously
Like No. 2, it is advantageous in far-infrared radiation. Next, one embodiment of the method for manufacturing an enamel heating element of the present invention will be described with reference to the drawings. 1 is a metal base made of a pipe made of iron, stainless steel, or the like. The metal substrate 1 is subjected to pretreatment such as degreasing, pickling, and neutralization in order to improve adhesion. Next, for 100 frits of the ingredients listed in Table 3 below, 175 potassium feldspar, 5 clay, 0.5 molten salt, and MnO ₂ as metal oxide.
Fe ₂ O ₃ 2 and 55 parts by weight of water were mill-blended into a slurry, and the slurry-like mixture was applied to the surface of the metal substrate 1 that had been subjected to the above-mentioned pretreatment, and enameled at 830°C. 80-200μ with a satin-like surface after baking
A blackish far-infrared emitting layer 2 with a film thickness of Table 3 Component name Mixture (weight ratio) SiO ₂ 36% B ₂ O ₃ 27 Na ₂ O 18 Al ₂ O ₃ 7 CaO 4 K ₂ O 4 CaF ₂ 2 MnO ₂ 1 NiO 0.5 CoO 0.5 The metal base 1 on which the infrared radiation layer 2 is formed accommodates a heating element 4 such as a nichrome wire connected at both ends to the left and right electrode terminals 3 in its hollow portion. 5 in the figure indicates a heat-resistant insulating filler such as MgO filled in the hollow part of the metal base 1,
Reference numeral 6 indicates an airtight material for enclosing the filler 5 in the hollow portion. If the metal substrate 1 is changed from a pipe to a flat plate and the far-infrared ray emitting layer 2 is formed on the surface of the flat plate, it can be used as a panel-shaped far-infrared radiating enamel heating element. The far-infrared radiating heating element manufactured in this manner has a black, satin-like far-infrared radiating layer, which is a heterogeneous glass layer having potassium feldspar particles dispersed therein, formed on its surface. By appropriately heating the heating element 4, strong far-infrared rays are emitted. In addition, for 100 frits of the ingredients in Table 3 above, 175 petalite or colemanite, 5 clay,
Stopper 0.5, _MnO2 and _Fe2O32 as metal oxides _,
They were mill-blended into a slurry with 55 parts by weight of water, the slurry-like mixture was applied to the surface of the pretreated metal substrate 1, and enamel baking was performed at 830°C to create a satin-like surface. A blackish far-infrared emitting layer 2 having a film thickness of 80 to 200 μm was formed. Hereinafter, a far-infrared radiating heating element manufactured in the same manner as in the above example has a black satin-like far-infrared radiating layer formed on its surface, which is a heterogeneous glass layer having petalite particles or colemanite particles dispersed therein. , the radiation layer emits strong far-infrared rays when the heating element 4 is appropriately heated. Furthermore, for 100 frits of the components listed in Table 3 above, potassium feldspar, petalite, colemanite and
175 parts by weight of ZrO ₂・SiO ₂ , 5 parts of clay, 0.5 parts of inhibitor, MnO ₂ and Fe ₂ O ₃ 2 as metal oxides, and 55 parts by weight of water are mill-blended into a slurry, and the slurry-like mixture is Apply it on the surface of the pretreated metal substrate 1 and heat it to 830℃.
It is enamel fired and has a satin-like surface.
A blackish far-infrared emitting layer 2 with a film thickness of 80 to 200 μm was formed. Hereinafter, the far-infrared radiating heating element manufactured in the same manner as in the above example includes potassium feldspar particles, petalite particles,
A black, satin-like far-infrared radiation layer, which is a heterogeneous glass layer containing dispersed colemanite particles and ZrO ₂ /SiO ₂ particles, is formed on its surface, and the radiation layer is heated by heating the heating element 4 as appropriate. Emits powerful far-infrared rays. The method of the present invention is as described above, and the first effect of the method of the present invention is that the adhesion of the enamel layer to the metal substrate is improved, there is no need to differentiate between the use of the lower glaze and the upper glaze, and only one glaze is applied. It is possible to manufacture a far-infrared radiating heating element only by enamel firing. The second effect is that the adhesion of the enamel layer to the metal substrate improves, making it resistant to mechanical shock.
Furthermore, it is possible to produce a far-infrared radiating heating element that does not peel or crack during cooling and heating cycles. The third effect is that by devising the composition of the frit, it is possible to add at least 50 parts (175 parts in the example) of one or more of potassium feldspar, petalite, and colemanite, or these and ZrO ₂ / SiO ₂ . The advantage is that it can form a powerful far-infrared radiation layer. The fourth effect is that one or more of potassium feldspar particles, petalite particles, and colemanite particles, or one or more of these particles and ZrO ₂ / SiO ₂ are mixed in a large amount, so one or more types of potassium feldspar particles, petalite particles, and colemanite particles or these particles are mixed.
ZrO ₂ and SiO ₂ particles are dispersed and present in the glass layer, forming a non-uniform glass layer and reducing the various drawbacks of conventional glass (splatter, chipping, etc.). The fifth effect is that the emissivity (represented by the ratio of a perfect black body to 1) is close to 1, so that far-infrared rays can be efficiently radiated. The sixth effect is that it can be mass-produced and is inexpensive because it can be performed in the same way as general enamel firing. The seventh effect is that a physically stable far-infrared emitting layer with high fire resistance and electrical insulation properties can be formed.

[Brief explanation of the drawing]

The drawing is a partially cutaway plan view showing an embodiment of an enamel heating element for far-infrared radiation manufactured by the manufacturing method of the present invention.

Claims (1)

[Claims] 1 Weight ratio SiO ₂ 35-36%, B ₂ O ₃ 26-27%,
_Na2O18 ~19%, _Al2O3 6~7%, CaO4 _~ 6%,
_K2O3 ~4%, _CaF2 1~3%, _MnO2 1~2%,
For 100 parts of frit containing 0.3 to 0.6% NiO and 0.3 to 0.6% CoO, one or more of potassium feldspar, petalite, colemanite, or these together with ZrO ₂ and SiO ₂
Add at least 50 parts of
0.2-0.5 parts, _MnO2 , _Cu2O , _{Fe2O3 , Al2O3 ,}
2 to 5 parts of one or more of the metal oxides CoO, NiO, Cr ₂ O ₃ , and Fe ₃ O ₄ and 45 to 55 parts of water are mixed into a slurry, and this slurry-like mixture is applied to a metal substrate. 1. A method for producing an enamel heating element for far-infrared radiation, characterized in that a far-infrared radiation layer is formed by only one time of enameling and enameling.