JPH0684270B2 - Infrared radiation coating - Google Patents

Description

TECHNICAL FIELD The present invention is in the field of infrared heating for performing radiant heating in heating, cooking, etc., in order to form a highly efficient infrared radiant body, metal,
The present invention relates to a coating applied to the surface of a heating body such as ceramics.

2. Description of the Related Art Conventional infrared radiation coating is a method in which oxides or compounds such as alumina, titania, zirconia, etc. are directly formed on the substrate by thermal spraying or sintered. Further, it is known to form a enamel coating by dispersing it in a binder such as glass frit.

In the case of the thermal spraying method, the coating forming step is very complicated and the film thickness is large, so that the material used is restricted from the viewpoint of absorbing the difference in expansion coefficient from the base material. In addition, the formed coating was porous and inferior in corrosion resistance.

In the case of the sintering method, heating at about 1300 to 1400 ° C. is necessary, so it is necessary to use a special ceramic as a base material.

In addition, in the case of the enamel type, since the film thickness is as thick as 100 μm or more, the coefficient of thermal expansion does not match and the adhesion to the base material is poor,
When heated to 600 ° C. or higher, the coating film exhibits fluidity, which is a drawback that it cannot be applied at high temperatures of 600 ° C. or higher.

Furthermore, in the conventional method, in the case of forming a far-infrared radiation coating that emphasizes long-wavelength infrared radiation by utilizing the wavelength selectivity of radiation, zirconia-based compounds and the like were often used. There was a problem that it was difficult to raise the emissivity to 0.8 or higher due to the influence of reflection.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention solves the above-mentioned conventional drawbacks.
By forming a thin film of ˜50 μm, the infrared emissivity in the long wavelength region of 6 μm or more is 0.9 or more, and the infrared emissivity in the short wavelength region of 2 to 6 μm is 0.8 or more. It is intended to provide a coating having a kind of quasi-blackbody radiation performance.

It is also an object of the present invention to provide a technique capable of forming a coating film on a metal surface in the same manner as in ordinary organic coating.

Further, it is also an object of the present invention to provide a coating film having excellent adhesion reliability even when used on a heating surface which is red-heated at 800 to 900 ° C. In the past, this type of technology has hardly been known.

Means for Solving the Problems In order to satisfy the above-mentioned conditions, the present invention uses polytitanocarbosilane as a binder, and a composite oxide containing zirconia or zircon as a main component, and a group of silica, alumina, and titania. A coating formed of a cured product of one or more selected oxides and oxides of one or more elements selected from the group of iron, manganese, copper, nickel and cobalt is used.

In a state where polytitanocarbosilane is dissolved in a solvent, other additives are dispersed in the binder, and a coating material is used to apply the composition on a target substrate, and as a cured product after firing. , To obtain an infrared radiation coating.

Polytitanocarbosilane is a polydimethylsilane synthesized by dechlorination polycondensation reaction of dimethyldichlorosilane, and a semi-inorganic polymer called polyborodiphenylsiloxane obtained by polycondensation of diphenyldichlorosilane and boric acid. It is obtained by heat polycondensation with a titanium compound.

Polytitanocarbosilane is an organometallic crosslinked polymer in which a polycarbosilane moiety mainly composed of a carbosilane skeleton is crosslinked and polymerized with a titanium compound, The functional group of Ti is 1 to 4 R: CnH ₂ n + 1.

A conventional coating using a cured product of polyborosiloxane resin as a binder requires a hygroscopic solvent such as N-methylpyrrolidone, resulting in poor handleability of the paint. Therefore film defects,
While color unevenness is likely to occur, polytitanocarbosilane has no solvent selectivity and is extremely easy to handle.

Since this polytitanocarbosilane is easily dissolved in an organic solvent, it is used in a dissolved state.

These compounds may be used alone as a zirconia or a complex oxide containing zircon as a main component, or zirconia or a rare earth element oxide such as La, Y, Ce, or Pr in zircon, and other SiO ₂ , V ₂ It is also possible to use a solid solution of oxides such as O ₅ , CaO and MgO.

Since these oxides and complex oxides have good absorption characteristics in the infrared region on the long wavelength side of 6 μm or more, the coating containing them becomes a high radiator in that region. However, since the refractive index of the zirconia compound is about 2.2, which is rather high, the emissivity is limited to about 0.8 due to the effect of surface reflection, and some measures must be taken to improve this.

For that purpose, it may be considered that the zircon or zirconia compound is not directly exposed on the surface of the coating film. For that purpose, the compounding ratio of zirconia, a zircon compound, etc. may be lowered so that the binder is exposed on the surface, but in this case, since the stability of the coating is poor and it becomes difficult to handle, zirconia and zircon are used. It is preferable to use a composite oxide whose main component has a surface coated with silica or alumina having a low refractive index. As a result, the infrared emissivity at 6 μm or more is 0.
9 or more.

On the other hand, as the one type oxide selected from the group of iron, manganese, copper, nickel and cobalt, the oxide may be used alone, or Fa ₂ O ₃ · MnO ₂ · CaO, Fe ₂ O ₃ · MnO ₂ · CaO / CoO, CuO /
It may be used as a complex oxide such as CoO. Most of these are black compounds and have a good absorption coefficient in the near infrared region. By adding these compounds, 6 μm
The following infrared emissivity on the short wavelength side is improved. Since these compounds also have a high refractive index, it is desirable to use them after performing the same surface treatment as the complex oxide containing zirconia or zircon as a main component.

The particle size of the composite oxide containing zirconia or zircon as a main component is also due to the light scattering effect, and when polytitanocarbosilane that can increase the emissivity is dispersed as a binder, the compounding ratio to polytitanocarbosilane is a weight ratio. 1/2 ~ 3/2
In the case where the particle size is in the range of 0.1 to 0.5 μm, good light scattering in the long wavelength infrared region can be obtained. It is considered that this is because the optimum condition is the distance between particles and the difference in refractive index from the binder.

The scattering effect of the oxides and complex oxides of one or more elements selected from the group of iron, manganese, copper, nickel and cobalt is such that the compounding ratio is 1/2 to weight ratio with respect to polytitanocarbosilane. When the particle size is 1/1, the particle size becomes good when the range of 0.1 to 1 μm is used. It is considered that the particle size is relatively small because there is scattering on the short wavelength side.

Furthermore, silica, alumina, and titania having a particle size of 1 to 5 μm can be used as a filler for obtaining ease of handling as a paint, as long as they do not adversely affect the infrared radiation performance and improve the physical properties of the coating. . The compounding ratio may be an amount up to 1/1 by weight with respect to polytitanocarbosilane.

This is effective in adjusting the viscosity of the coating material within a desired range, is effective in improving the physical properties of the coating film, particularly hardness, and does not adversely affect the infrared radiation performance.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram of the coating film of the present invention. Using polytitanocarbosilane 1 as a binder, zirconia or a composite oxide 2 containing zircon as a main component therein, and one or more oxides 3 selected from the group of silica, alumina and titania, and iron and manganese. , Oxides of one or more elements selected from the group of copper, nickel, cobalt, and complex oxides 4
A coating film 5 made of a hardened material containing is formed on a base material such as metal or ceramics and used. 6 is a base material.

As the polytitanocarbosilane, "Tyrannocoat" manufactured by Ube Industries, Ltd. was used.

A coating material was prepared by mixing 100 parts by weight of the Tyrannocoat in the above-mentioned manner with the composition shown in the table and applied on a stainless steel plate with a film thickness of 15 μm, and then baked at 300 ° C. for 30 minutes to obtain a film.

The surface temperature of the thus-obtained test piece was set at 500 ° C., and the infrared spectral radiation characteristics of each coating were evaluated using a spectral radiation device manufactured by JASCO Corporation.

FIG. 2 shows the infrared spectral radiation characteristics of a typical coating.

In FIG. 2, a is the case of stainless steel only, and b is the case of the conventional coating of ZrO ₂ —CaO (5%) sintered at 1350 ° C. The coatings from P-1 to P-4 show radiation characteristics like c. c is for P-4 and shows similar performance from P-1 to P-4.

With respect to the coating film of the present invention, the contribution of the film thickness did not significantly change the spectral radiation characteristics in the range of 10 to 50 μm.

When the thickness is 10 μm or less, it is considered that the influence of the base material appears, and the emissivity particularly on the long wavelength side decreases.

When it exceeds 50 μm, the coating becomes weak against heat shock. In addition, there is an increased risk of foaming during firing.

The coating film formed as described above showed extremely excellent characteristics. Especially excellent in heat shock resistance, 80
Even in the test of heating in water to 0 ° C and injecting in water, no abnormality such as peeling or cracking was observed in the coating even after repeating 10 cycles.

EFFECTS OF THE INVENTION As described above, the effects of the present invention are as follows: (1) The average infrared emissivity of the thin film is 10 to 50 μm.
It is possible to obtain a radiator having excellent heat resistance of 8 or more (especially the long wavelength infrared emissivity of 6 μm or more is 0.9 or more).

(2) It can be applied by a spray method, and electrostatic coating is possible. Since a film can be easily formed by the same degreasing process as that of ordinary organic paints and the productivity is extremely excellent, it is inexpensive.

(3) Since the film can be formed by heating at the final temperature of 300 ° C, it can be applied to many heat-resistant metals, and the applicability of the base material is wide.

(4) Since it can be applied by a spray method, it can be applied to complicated base materials such as wire mesh metal.

(5) Since it is a thin film, it has extremely good adhesion and is particularly resistant to heat shock, and a highly reliable film can be obtained.

And so on.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an infrared radiation coating of one embodiment of the present invention, and FIG. 2 is an infrared spectral radiation characteristic diagram. 1 ... polytitanocarbosilane, 2 ... composite oxide containing zirconia or zircon as a main component, 3 ... at least one oxide selected from the group of silica, alumina, and titania, 4 ... iron, manganese , An oxide of at least one element selected from the group of copper, nickel and cobalt, and a composite oxide.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mamoru Isotani 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-60-251185 (JP, A) JP-A-59- 232984 (JP, A)

Claims (2)

[Claims] 1. A composite oxide containing polytitanocarbosilane as a binder and containing zirconia or zircon as a main component, and at least one oxide selected from the group consisting of silica, alumina and titania, and iron, manganese, copper, nickel,
An infrared radiation coating comprising a cured product of an oxide or a complex oxide of at least one element selected from the group of cobalt. 2. A particle size of a composite oxide containing zirconia or zircon as a main component is 0.1 to 0.5 μm, and a compounding ratio to polytitanocarbosilane is 1/2 to 3/2 by weight, silica, The particle size of alumina and titania is in the range of 1 to 5 μm, and the particle size of oxides and complex oxides of at least one element selected from the group of iron, manganese, copper, nickel and cobalt is 0.1 to 1 μm. The infrared radiation coating film according to claim 1, wherein the compounding ratio is in the range of 1/2 to 1/1 by weight with respect to the polytitanocarbosilane.