JPH0643267B2 - 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. In particular, it is targeted at heat resistant metal base materials such as stainless steel.

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 film forming process is very complicated and the film thickness is large, so that the material to be 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, since heating at about 1300 to 1400 ° C. is required, it is necessary to use a special ceramic as a base material.

Further, 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 with the substrate is poor, or the coating film exhibits fluidity when heated to 500 ° C. or more. There was a drawback that it could not be applied at high temperatures above ℃.

Further, a coating is known in which a heat resistant coating using silica or the like as a binder is formed on a corrosion resistant substrate such as stainless steel. In the case of heat resistant coatings such as these, it is necessary to form a coating film in order to make properties such as heat shock resistance advantageous, but when used in an environment with severe humidity and corrosion resistance, crevice corrosion will occur. There was a problem in corrosion resistance.

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 0 to 50 μm, the infrared emissivity is 0.
It provides an infrared high radiation coating of 8 or more. A film can be formed on a metal surface by the same method as that of ordinary organic coating, and a film having excellent adhesion reliability is provided on a surface heated up to 500 ° C, particularly in a severe corrosive environment. This is also the aim of the present invention. Traditionally, this kind of technology
Little was known.

Means for Solving the Problems In order to solve the above problems, the present invention has a surface roughness of 0.4 μm.
On the above substrate, polytitanocarbosilane was used as a binder, fluororesin was contained in an amount of 5 to 15 parts by weight with respect to the binder, and other fillers and a cured product of pigment were used. Is used to form a coating having a content of 2 wt% or less.

In a state where polytitanocarbosilane is dissolved in a solvent, other additives are dispersed in the binder, and a paint is used to apply it to a target substrate having a surface roughness of 0.3 μm or more. An infrared radiation coating is obtained as a cured product after firing.

Action Polytitanocarbosilane is a polydimethylsilane synthesized by dechlorination polycondensation reaction of dimethyldichlorosilane, a semi-inorganic polymer called polyborodiphenylsiloxane obtained by polycondensation of diphenyldichlorosilane and boric acid, and titanium. It is obtained by heat polycondensation with a 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, It is made up of basic structural units such as.

Since this polytitanocarbosilane is easily dissolved in an organic solvent, it is used in a dissolved state. It is desirable to use polytitanocarbosilane having a molecular weight of 5,000 to 50,000.

As the fluororesin, fine powder having a molecular weight of about 1,000 to 8,000 and a particle size of about 0.1 to 1 μm is used.

In addition, a filler and a pigment are added to increase the infrared emissivity. These fillers and pigments are selected from the group consisting of zirconium, silicon, aluminum and titanium 1
As the main component, oxides, carbides, and nitrides of one or more elements, and oxides and complex oxides of at least one element selected from the group of iron, manganese, copper, nickel, and cobalt may be used. The former is a white compound and the latter is a colored compound. The former white compound has a high absorption coefficient in the infrared region having a long wavelength of 6 μm or more. The latter transition element oxide is a black compound, and conversely has a high absorption coefficient on the short wavelength side of 6 μm or less. Therefore, by appropriately mixing both, a coating having a high infrared emissivity over the entire infrared wavelength range can be obtained. The particle size of these fillers and pigments is preferably in the range of 0.05 to 1 μm. The compounding ratio of the filler to the polytitanocarbosilane is in the range of 1/2 to 3/2 by weight, and the compounding ratio of the pigment to the polytitanocarbosilane is in the range of 1/2 to 1 by weight.
It is desirable to use the range of / 1.

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. On a substrate having a surface roughness of 0.3 or more, a coating containing fluororesin 3, filler 4, and pigment 5 is formed by using polytitanocarbosilane 2 as a binder. The coating shows a high infrared emissivity due to the inclusion of the filler 4 and the pigment 5. In order for this type of coating to have heat resistance, it is necessary that the coating be porous, which absorbs the difference in the coefficient of thermal expansion from the base material and can withstand heat shock. To moisture resistance,
Corrosion resistance decreases, and the base material corrodes through the pinholes in the coating. Especially, when stainless steel is used as the base material, the progress of crevice corrosion is remarkable.

In the case of the present invention, since the fluororesin 3 is contained in the coating film, the coating film has water repellent property and thus has excellent corrosion resistance.

Usually, when preparing this kind of paint, the paint is prepared using a paint disperser. Usually, the paint is prepared by stirring the paint in a medium such as a steel ball, but the media wears during dispersion and mixes into the paint. When stainless steel is used as the base material, if metal-based media is mixed in the coating, the metal corrodes in a corrosion resistant environment, and the resulting metal ions reduce the stainless steel base material, causing significant corrosion of the stainless steel base material. I found out. It was confirmed that the influence of corrosion of the base material was not observed when the amount of metal mixed in the coating film due to the metal-based medium was 2 wt% or less.

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

A coating material was prepared according to the composition shown in Table 1 with respect to 100 parts by weight of the Tyranno coat. The coating material of Table 1 having a film thickness of 20 μm was coated on various substrates having different surface roughness and baked at 300 ° C. for 30 minutes. After continuous salt spray test for 200 hours, cellophane tape peeling test was performed. The results of carrying out are shown in Table 2. In addition, stainless steel is used as a base material for SUS-304.
Was used. Two types of substrates having different surface finishes were tested. The surface roughness is expressed by the center line surface roughness (ra).

Next, for four types of samples with different surface roughness, P-
A similar test was performed with the two paints. The surface roughness of the sample is
It was 0.22, 0.28, 0.44 and 0.47. As a result, peeling was observed in the former two cases, whereas peeling was hardly observed in the latter two cases. When the type of the base material was changed to SUS-321 and tested, the occurrence of rust was small, but the same tendency was observed. From the above, it is considered that the surface roughness of the base material of 0.4 μm or more is effective for the coating composition of this composition. Further, regarding the blending of the fluororesin, it is effective from 5 parts by weight, but if it exceeds 20 parts by weight, it is considered that the adhesion to the base material is deteriorated. All of these coatings showed excellent infrared radiation performance, and the infrared emissivity was 0.8 or more.

When the film thickness of the present coating is 10 μm or less, the emissivity decreases and the corrosion resistance also decreases. When it exceeds 50 μm, the coating becomes weak against heat shock.

This coating is a hard coating with a pencil hardness of 7H or more, and has sufficiently excellent adhesion reliability even under a heating environment of 500 ° C.

In particular, it was excellent in heat shock resistance, and even when it was cooled from 500 ° C. to water, no abnormality such as peeling or cracking was observed in the coating.

Effects of the Invention As described above, the effects of the present invention are (1) a heat resistant coating formed on a heat resistant metal such as stainless steel, but a coating having extremely excellent corrosion resistance even in a severe corrosive environment can be obtained.

(2) Although it is a thin film having a thickness of 10 to 50 μm, a radiator having an infrared emissivity of 0.8 or more and excellent heat resistance can be obtained.

(3) It can be applied by spraying, and electrostatic coating is possible. A film can be easily formed in the same degreasing process as that for ordinary organic paints, and it is inexpensive because it has excellent productivity.

(4) Since the coating can be formed by heating at 300 ° C. at the end, it can be applied to many heat-resistant metals.

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

(6) 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 a main part of an infrared radiation coating according to an embodiment of the present invention. 1 ... Substrate with surface roughness of 0.3 or more, 2 ... Polytitanocarbosilane, 3 ... Fluorine resin, 4 ... Filler, 5 ... Pigment.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mamoru Isotani 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-62-167271 (JP, A) JP-A-60- 27669 (JP, A)

Claims (1)

[Claims] 1. A substrate having a surface roughness of 0.4 μm or more, containing 5 to 15 parts by weight of a fluororesin as a binder and a fluororesin as a binder, and curing other fillers and pigments. An infrared radiation coating consisting of a body and having a metal content of 2 wt% or less.