JPH0258757B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a planar heating element with improved heat radiation performance.

Traditionally, this type of heating element consists of an electric heater made of metal foil, such as stainless steel or aluminum, in a serpentine shape, sandwiched between insulating sheets such as mica plates or asbestos plates.
For example, they are used for heating in so-called panel heaters and floor heaters, or for heat retention in rice cookers, jars, and the like. However, this device has the disadvantage that the heat radiation performance as a whole is poor due to the low thermal emissivity of the insulating sheet sandwiching the electric heater, so a high heat radiation material is coated on the surface of the insulating sheet. The idea is to improve the overall heat radiation performance. However, in the case where the high heat radiation material is coated on the surface of the insulating sheet as described above, there is a drawback that the high heat radiation material is easily peeled off, and furthermore, the manufacturing process is increased due to the coating work. The present invention has been made in view of the above-mentioned circumstances, and its purpose is to improve heat radiation performance without suffering from peeling of high heat radiation material and without increasing manufacturing steps. To provide a shaped heating element.

An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. 2 and 3 are insulating sheets fixed with adhesive, for example, with the electric heater 1 sandwiched between them, and these insulating sheets 2,
3 are basically composed of so-called composite mica, which is made by laminating mica pieces into a thin plate shape using silicon or an inorganic insulating material as a binder. A high heat radiation material 4 made of an oxide is mixed as shown in FIG.

That is, the assembled mica plates 2 and 3, which are electrical insulators, are manufactured by, for example, solidifying mica powder with silicone varnish and heating and drying it under pressure using a press. The electric heater 1 is used to heat both mica 2 and 3 at all stages of complete drying in the manufacturing process of this composite mica board.
Since the mica plates 2 and 3 are sandwiched between them and heated and pressed, they are completely integrated with both mica plates 2 and 3, and even if the electric heater 1 generates heat and the whole body warps during actual use, the close contact will not occur. maintain the condition. The electric heater 1 is manufactured by etching or punching an extremely thin stainless steel plate of several + microns. In the planar heating element configured as described above, the mica plate assembly 2 located on the front side forms a radiation surface 20. The present inventor mixed metal oxide powder into silicon varnish, which is a binder, in order to improve the emissivity of a composite mica plate.

As a result, it was possible to achieve a spectral emissivity of about 80% or more at wavelengths of 2.5 to 5 μm and 8 to 12 μm.

Now, in the case of this embodiment configured as above,
Since the high heat radiation material 4 is mixed into the binder of the insulating sheet 2, it does not peel off unlike conventional materials applied to the surface.
In addition, since it is mixed in at the same time as the binder is created, it does not require an increase in manufacturing steps like conventional coating work, and while producing this effect, it can of course also improve the overall heat radiation performance. It is.

In the case of the above embodiment, the insulating sheet 3 on the back side
The binder does not contain any high heat radiation material, which has the advantage of suppressing the heat radiation to the back side when it is desired to improve the heat radiation performance only on the front side. This is not necessarily necessary, and a heat radiation material may also be mixed into the insulating sheet 3 on the back side to improve the heat radiation performance on the front and back sides in the same way. Further, the electric heater 1 may be made of a cotton-like material instead of a strip-like material.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings, and may be implemented by appropriately changing the specific materials and shapes of each part without departing from the scope of the invention. .

In summary, the present invention is a planar heating element consisting of an electric heater spread out in a strip or a linear shape sandwiched between heat-resistant insulating sheets, in which at least the insulating sheet on the front side is made of laminated mica. A planar heating element characterized by being made of an insulator containing a metal oxide in a binder,
This provides an excellent effect of improving heat radiation performance without having to worry about peeling of the high heat radiation material or having to increase the number of manufacturing steps.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, with FIG. 1 being a broken perspective view and FIG. 2 being a longitudinal sectional view. In the figure, 1 is an electric heater, 2 and 3 are insulating sheets, and 4 is a high heat radiation material.

Claims (1)

[Claims] 1. A planar heating element consisting of an electric heater arranged in a strip or a linear shape sandwiched between heat-resistant insulating sheets, with at least the insulating sheet on the front side
A planar heating element characterized in that it is made of laminated mica and is made of an insulating material in which a metal oxide is mixed into the binder.