JPS6354314B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention is a method of transferring thermal energy to an object, in which electromagnetic waves emitted from a heat source are directly absorbed into the object to be heated without any medium, thereby causing molecular vibrations within the object. The paint used to form the far-infrared emitter (surface) in a far-infrared heater emits infrared rays in the 3μ to 20μ wavelength range, which is easily absorbed by many substances and is thermal radiation that can perform efficient heating with a thermal effect. The present invention relates to a composition and a far-infrared radiant heater constructed using the coating composition. <Prior art> The most important and strongly desired requirements for far-infrared radiant heaters are high emissivity of the radiator (surface) and low radiation in the visible range at relatively low surface temperatures of 100°C or higher. There is a lot of radiation in the infrared region. In response to this, radiators (surfaces) made of various ceramics such as alumina, graphite, and zirconia have been put into practical use. In particular, high-purity alumina, which is superior to other ceramics in terms of far-infrared radiation characteristics, is often used. However, in the past, a special paint for forming the far-infrared radiator (surface) had not been developed, and plasma spraying of alumina was exclusively used. <Problems to be solved by the invention> The plasma spraying means described above uses alumina powder.
It is melted using an extremely high temperature non-oxidizing heat source of about 5000 to 7000℃, and then accelerated by a plasma jet through a thermal spray gun and sprayed onto the surface of a metal plate or a heat-resistant insulating plate such as mica or asbestos to form an alumina film. Not only is it necessary to form a thermal spray base (cathelyzer) such as alumina vapor deposition on the plate surface, but it also requires extremely high thermal energy and kinetic energy, resulting in enormous manufacturing costs. Moreover, since the alumina film formed by plasma spraying is easily split, the radiation surface is also limited to a one-dimensional flat heater, which has various drawbacks such as low applicability. <Means for Solving the Problems> The first invention provides a coating composition that allows the formation of far-infrared radiators with radiation characteristics comparable to those formed by plasma spraying very easily and at low cost. The purpose is to provide something, and this second
An object of the invention is to provide a far-infrared radiant heater that is low in cost and has high versatility in terms of form by utilizing the above-mentioned composition. Therefore, the composition of the far-infrared radiation coating material according to the first invention, which was developed to achieve the above-mentioned first object, contains alumina alone or alumina and an inorganic oxide powder in a proportion of 50 parts or less by weight. This second book is characterized in that it is made by dispersing a mixture of
The far-infrared radiant heater according to the invention uses a coating composition in which alumina alone or a mixture of alumina and an inorganic oxide powder in a proportion of 50 parts or less by weight is dispersed in a binder.
Alternatively, it is applied to the surface of a heat-resistant insulating plate made of mica, asbestos, glass, etc. in a film with a thickness of several microns or more, preferably 20 microns or more, and is heat treated to form a far-infrared radiator that emits a large amount of wavelengths of 5 μm or more. However, this radiator is characterized by a configuration in which a planar heater element is superimposed on the back of the radiator. <Actions and Effects of the Invention> The far-infrared radiation coating composition according to the first invention, which has the above-mentioned characteristics, has high-purity alumina with excellent far-infrared radiation characteristics as a main component, and has heat-resistant alumina. It is dispersed in a binder such as methylphenyl silicone resin, which has large water repellency, excellent electrical insulation, chemical resistance, aging resistance, and non-volatility. Heat resistance, electrical insulation, chemical resistance and It fully satisfies the various properties that are highly required in terms of durability as a far-infrared radiator, such as aging resistance, and in terms of radiation properties, the radiation at a temperature of 100℃ or higher is 50% or more at a wavelength of 5 to 25 μm. , and less than 30% at a wavelength of 5 μm or less, making it possible to form a radiator almost equivalent to that formed by plasma spraying. Incidentally, FIG. 6 is a graph comparing the radiation characteristics of a radiator formed by plasma spraying of alumina and a radiator formed by applying the composition of the present invention, and a wavelength of approximately 5 μm or more is selected. It is clear that there is no difference at all between the emissivity of the present invention shown by the solid line and the emissivity of plasma spraying shown by the dotted line in emitting a large amount of radiation. Therefore, compared to conventional plasma spraying, there is no wastage of thermal energy or kinetic energy, and the desired radiator can be formed very easily and at low cost. Further, the far-infrared radiant heater according to the second invention can be applied by applying the above-mentioned coating composition to the surface of a metal plate or a heat-resistant insulating plate in the form of a film with a thickness of several microns or more, preferably 20 microns or more. By effectively utilizing the above-mentioned properties of the composition, a heater with excellent durability and radiation characteristics can be manufactured easily and at low cost. Moreover, unlike thermal spray coatings, alumina is uniformly dispersed within the coating thickness, which has excellent resistance to mechanical stress, making it easy to apply to curved surfaces without causing splitting, and therefore limiting the use of flat heaters. It can be applied to two-dimensional and three-dimensional curved heaters, such as distributed and centralized types, depending on the purpose of use.
This made it possible to achieve a sufficiently high degree of versatility in terms of form. <Example> Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 1 shows the cross-sectional structure of the far-infrared radiant heater, and FIG. 2 shows the external appearance. 2 is a metal plate or a heat-resistant insulating plate made of mica, asbestos, glass, etc., which constitutes the far-infrared radiator; A far-infrared radiator is formed by uniformly applying Composition 1, which will be described later, over the entire surface of the material in the form of a film with a thickness of several microns or more, preferably 20 microns or more, by brushing or spraying, and then heat-treating it so that the solvent evaporates. 3. 4 is an inorganic insulating plate 5 made of mica, asbestos, etc., which has excellent heat resistance and electrical insulation properties, on the back side of the far-infrared radiator 3.
This is a planar heating element made by polymerizing a thin nichrome plate, stainless copper plate, etc. into any shape by etching or press die cutting, or heating element metal powder paste into any shape. It may be a printed version or a nichrome wire wrapped around an electrically insulating plate made of mica or the like. Reference numeral 6 denotes a far-infrared reflecting plate superimposed on the back side of the heater element 4, which is made by laminating an aluminum foil 6B on the back side of a heat-resistant electric insulating board 6A made of mica or the like. By fitting and integrating each of the above-mentioned components into an aluminum or iron case 7 with a U-shaped cross section, a one-dimensional planar far-infrared radiation heater as shown in Fig. 2 is constructed. be. The following may be considered as the coating composition 1 for constructing the above-mentioned radiator 3.

[Table] Regarding the radiation characteristics of each of the above compositions,
As the temperature increases, radiation with a wavelength of 5 μm or less increases. As the reflector 6 in the far-infrared radiation heater described above, an aluminum plate or a stainless steel plate may be used as shown in FIG. By folding it back in its position, radiation can be made even better. In addition, the form of the radiator 3 is not limited to a flat plate, but may be a concave curved plate or a convex curved plate as shown in Figures 4 and 5, which locally radiates far infrared rays in a concentrated manner, or diffused radiation. In addition, it can be configured in any shape such as a cylindrical shape or a semi-cylindrical shape depending on the purpose of use.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention,
Fig. 1 is a cross-sectional structural diagram of the heater, Fig. 2 is a schematic perspective view of the entire heater, Fig. 3 is a cross-sectional structural diagram showing another embodiment, and Figs. 4 and 5 are also schematic diagrams showing different embodiments. The cross-sectional view and FIG. 6 are characteristic comparison graphs. 1 is a paint composition, 2 is a metal plate or a heat-resistant insulating plate, 3 is a far-infrared radiator, and 4 is a heater element.

Claims (1)

[Claims] 1. A far-infrared radiation coating composition comprising alumina alone or alumina mixed with inorganic oxide powder in a proportion of 50 parts or less by weight, dispersed in a binder. 2 The above alumina has a particle size of 120μ or less and a purity of 85
% or more of the composition according to claim 1. 3. The composition according to claim 1, wherein the binder is a silicone resin, a phosphate, or a silicate. 4 The inorganic oxide powder contains titanium, silicon,
The composition according to claim 1, which is one or a mixture of oxide powders of zirconia, iron, copper, cobalt, nickel, manganese, and chromium. 5 Coating composition 1, which is made by dispersing alumina alone or alumina mixed with inorganic oxide powder at a ratio of 50 parts by weight or less, in a binder, is applied to metal plates or heat-resistant materials such as mica, asbestos, glass, etc. The surface of the insulating plate 2 is coated with a thickness of several microns or more, preferably
Coated into a film of 20μ or more and heat treated to achieve a wavelength of 5μm.
constitutes a far infrared radiator 3 that emits a large amount of the above,
A planar heater element 4 is attached to the back of this radiator 3.
A far-infrared radiant heater made by polymerizing. 6 The above alumina has a particle size of 120μ or less and a purity of 85
% or more of the heater according to claim 5. 7. The heater according to claim 5, wherein any one of a silicone resin, a phosphate, or a silicate is used as the binder. 8. The heater according to claim 5, wherein the inorganic oxide powder is one or a mixture of two or more of titanium, silicon, zirconia, iron, copper, cobalt, nickel, manganese, and chromium oxide powder.