JPH10168352A - Heat-resistant coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant coating composition that can give coating film excellent in resistance to heat and weather, causing no discoloration even when it is used under high temperature conditions as much as 350-600 deg.C. SOLUTION: This heat-resistant coating composition is prepared by dispersing a heat-resistant pigment comprising a powder having optically interfering multilayer coating films having a plurality of different refractive indexes together with a solvent solution of vehicle giving a clear coating layer or by dispersing the pigment together with the vehicle in the solvent, on the surface of the core particles 1 causing no deformation and discoloration even at high temperature as much as 350-600 deg.C or by dispersing. In a preferred embodiment, at least one layer in the multilayer coating film 2, 3 comprises an inorganic metal compound or metal and the medium giving a clear coating layer is composed of at least one of resin selected from a pure silicone resin, fluororesin or silicone-modified resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant coating composition which gives a coating film which can withstand high temperatures, and more particularly, can provide a coating film which can withstand high temperatures of 350.degree. C. or more and which is rich in weather resistance and light resistance. The present invention relates to a coating composition having heat resistance, weather resistance, and light resistance.

[0002]

2. Description of the Related Art Conventionally, when a coating film is formed by using a paint, when the place of use is a place where the temperature is high, a heat-resistant paint that can withstand the temperature is used.
By the way, even when a coating composition developed for heat resistance or weather resistance is used, the heat resistance temperature of a coating film obtained by applying the coating composition is generally low. The reason is that the pigment used in the coating composition has low thermal stability at high temperatures. For example, an organic pigment discolors or oxidizes and burns at 300 ° C. or higher. In addition, even inorganic pigments having relatively high thermal stability are liable to undergo thermal deterioration, and are often discolored or faded by reaction with additives or adhesive substances. Furthermore, prolonged exposure to sunlight often results in fading. The coating composition usually contains an inorganic pigment or an organic pigment,
It consists of a medium in which a medium (vehicle) as a film forming agent is dispersed in a solvent in which the pigment is dispersed. However, in a conventional paint using a pigment, the pigment itself contained therein has a stable color tone at a temperature of 350 ° C. or more. There was nothing.

Conventionally, in a heat-resistant paint composition, a medium (vehicle) for a heat-resistant paint is classified according to its use temperature.
Up to a use temperature of about 165 ° C., an organic medium and a silicone-modified organic medium can be used.
Up to about 16 ° C, a silicone-modified aluminum medium or a silicone medium and a heat-stable color pigment can be used. Up to a use temperature of about 424 ° C, a silicone medium and an aluminum pigment or a silicone medium and a black / gray pigment are used. Up to a working temperature of around 538 ° C., a silicone medium and an aluminum pigment can be used, and up to a working temperature of around 650 ° C., a silicone-modified aluminum medium can be used, At 650 ° C. or higher, it is no longer possible to use a heat-resistant medium, and there is no other choice but to use ceramic coating.

[0004] On the other hand, the present inventors have previously made a metal or metal compound powder as core particles, disperse the core particles in a metal alkoxide solution, and hydrolyze the metal alkoxide on the surface of the core particles. Forming a metal oxide film on the surface of the core particles, further dispersing the metal oxide film-formed particles in a metal alkoxide solution of a metal different from the metal alkoxide, the metal alkoxide A method for forming a plurality of different metal oxide films on the core particles by repeating the method of hydrolysis on the surface of the particles has been invented (Japanese Patent Application Laid-Open No. 6-22).
8604). Further, the present inventors further improved the powder having the multilayer metal oxide coating, and not only the metal oxide coating, but also a multilayer coating having a plurality of metal oxide coatings and metal coatings alternately. (JP-A-7-90310). Similarly, a multi-layered metal oxide film is formed on the surface of the metal or metal compound powder, but the powder coated with the multi-layered metal oxide film is heat-treated to form a denser and more stable multi-layered metal oxide film. Filed a patent for manufacturing powder having
-80832).

In the method of using a metal alkoxide as a raw material to form a coating film of a metal oxide on the surface of a metal powder or a metal compound powder, the metal alkoxide is an expensive compound. Naturally, the price of the product developed by using it is also expensive, so that the use of the product is very limited. To overcome this weakness, we have:
If the core powder particles or the underlying coating film are resistant to acid or alkali, a metal hydroxide aqueous solution precipitates from the metal salt aqueous solution by hydrolysis with the addition of a stronger acid or alkali. Then, a technique capable of forming a uniform coating film of a metal oxide with the metal hydroxide was developed and a patent was applied for. Furthermore, the present inventors have recently formed a multilayer coating film having a different refractive index on the surface of a powder composed of an inorganic or organic substance having a wide specific gravity of 0.1 to 2.8. A patent application was found that a color powder having a stable color tone such as blue, green, and yellow can be obtained without adjusting the interference waveform of the reflected light from the substrate and using a dye or a pigment. According to the invention, a colored powder that can be stably dispersed in a solvent having a specific gravity lower than 1.0 such as an organic solvent can be obtained.

[0006]

SUMMARY OF THE INVENTION Production equipment which is used for a long time in a high temperature state, such as a high temperature heat treatment apparatus, a high temperature reaction apparatus and a high temperature melting apparatus, and general-purpose equipment which is used for a long time in a high temperature state, such as a high temperature heater and cooking utensil. It is often necessary to apply a coating to a part where the device or apparatus is exposed to a high temperature for the purpose of protecting the device or apparatus from oxidation and maintaining the appearance. For this reason, paints that do not change or fade even when exposed to a high temperature for a long time are desired. In addition, weather-resistant and light-resistant paints are desired for coatings applied to equipment and instruments used outdoors for a long time. According to the present invention, the operating temperature is 350
It is an object of the present invention to provide a coating composition which does not fade even at a high temperature of 0 ° C. or less, and which can provide a coating film having excellent heat resistance and weather resistance.

[0007]

While studying the means for solving the above problems, in the multilayer coating film powder invented by the present inventor, the multilayer coating film for forming the light interference film is used. Since the constituent metal oxide film or the material forming the metal film is stable to heat, the multilayer coating film forming the light interference film is stable to heat, and as a result, With the idea that a coating composition for heat resistance could be obtained if used, the present inventors reached the present invention by conducting research on the basis thereof. That is, the present invention has solved the above-mentioned problems by the following means. (1) Transparent coating of a pigment composed of a powder having a plurality of light interference multilayer coatings having different refractive indices on the surface of powder core particles of a material which does not cause deformation or coloring at a high temperature of 350 ° C. or more and 600 ° C. or less. A heat-resistant paint composition characterized by being dispersed in a solvent together with a solvent solution or a vehicle for a film-forming vehicle.

(2) The heat-resistant coating composition according to (1), wherein at least one layer of the light interference multilayer coating is an inorganic metal compound layer. (3) The heat-resistant coating composition according to (1), wherein at least one layer of the light interference multilayer coating is a metal layer or an alloy layer. (4) The medium for providing the transparent coating film is pure silicon resin,
The heat-resistant paint composition according to the above (1), comprising one resin selected from a fluororesin and a silicon-modified resin.

The essence of the present invention is to provide a pigment having a color by providing a plurality of light interference multilayer coatings having different refractive indexes on the surface of the powder core particles. If the refractive index and film thickness of each layer of the multilayer coating do not change significantly, the color does not change, and since the refractive index and film thickness of each layer does not change much with temperature, the color does not change up to high temperatures.
A stable color tone is maintained even at a high temperature of 50 ° C to 600 ° C. Further, the pigment of the present invention does not change its color tone even when exposed to sunlight for a long time because the shape of the powder core particles and the refractive index and the film thickness of each layer of the multilayer coating do not change. For this purpose, a metal oxide having high thermal stability or a metal itself may be used, and a superior advantage in that a colored substance (dye or organic pigment) having low thermal stability or chemical stability may not be used. is there.

In the present invention, the powder core particles constituting the core of the pigment powder may be organic or inorganic.
Since it is required that the material does not undergo deformation or coloring at a high temperature of 600 ° C. or less, inorganic materials are preferable, and organic materials are considerably limited.
The apparent specific gravity of the powder core particles is not particularly limited, and in a low-viscosity coating material, in order to improve the dispersion stability of the pigment dispersed in the medium, a low apparent density close to the organic solvent serving as the medium is used. It is desirable to use powder core particles having a specific gravity.

In the present invention, the inorganic material constituting the powder core particles made of the inorganic material includes metals such as iron, nickel, chromium, titanium, and aluminum;
Metal alloys such as nickel and iron-cobalt alloys, as well as iron-nickel alloy nitrides and iron-nickel-cobalt alloy nitrides, and various inorganic compounds, such as metal oxides such as iron, nickel, chromium, and titanium , Aluminum, silicon (in this case, silicon is classified as a metal), etc., alkaline earth metal oxides such as calcium, magnesium, barium and the like, or composite oxides thereof, clays, glasses, etc. Is mentioned. In particular, examples of powder core particles having a small apparent specific gravity include inorganic hollow particles such as shirasu balloons (hollow silicic acid particles), fine carbon hollow spheres (crecassphere), silica fine hollow spheres, and calcium carbonate fine hollow spheres. Can be

In a pigment colored by providing a plurality of light interference multilayer films having different refractive indexes on the surface of the powder core particles, a powder made of an organic substance can be used as the material of the powder core particles. Examples of the organic substance constituting the powder core particles of the present invention include natural and synthetic polymer compounds. However, many natural and synthetic polymer compounds cannot be used because they undergo deformation and oxidative discoloration when exposed to high temperatures of 350 ° C. or higher (600 ° C. or lower). Among the heat-resistant condensable polymer compounds subjected to cross-linking, for example, polyamide resins, polyimide resins, epoxy resins, melamine resins, and the like, suitable for use can be found.
The powder core particles may be non-uniformly shaped powders, but are preferably spherical powders.

In the pigment powder of the present invention, the plurality of coating layers formed on the surface of the powder core particles need to have different refractive indexes from each other, and constitute the coating layers. Materials are inorganic metal compounds, metals or alloys,
It is desirable to arbitrarily select from among organic and organic substances. Examples of the inorganic metal compound constituting the coating layer include metal oxides as typical ones, and specific examples thereof include, for example, iron, nickel, chromium, titanium, aluminum,
Oxides such as silicon, calcium, magnesium, barium and the like, and composite oxides thereof are mentioned. Further, examples of the metal compound other than the metal oxide include metal nitrides such as magnesium fluoride and iron nitride, and metal carbides. Examples of simple metals constituting the coating layer include metallic silver, metallic cobalt, metallic nickel, metallic iron and the like, and metallic alloys include iron / nickel alloy, iron / cobalt alloy, iron / nickel alloy nitride, iron / nickel / And cobalt alloy nitride.

The organic substance constituting the coating layer may be the same as or different from the above-mentioned organic substance constituting the core, and is not particularly limited, but is preferably a resin. Specific examples of the resin, polyamide resin, polyimide resin,
Epoxy resins, melamine resins and the like can be mentioned. As described above, various materials can be used as the material constituting the coating layer, and the combination of these materials is determined in consideration of the refractive index of each coating layer, and the type, purpose, It is necessary to select an appropriate material according to the material, heat resistance, light resistance and the like. The particle size of the pigment powder of the present invention is not particularly limited and can be appropriately adjusted depending on the purpose, but is usually in the range of 0.01 μm to several mm.

Further, each unit coating layer constituting the plurality of coating layers may have a thickness set for each unit coating layer so as to have an interference reflection peak or an interference transmission bottom of a specific same wavelength. desirable. More preferably, the thickness of each unit coating layer is set by the following formula (I): N × d = m × λ / 4 (I) [where N is a complex refractive index, d is a basic thickness, and m is Integer (natural number), λ represents the wavelength of the interference reflection peak or the interference transmission bottom, and N is the following formula (II): N = n + iκ (II) (n is the refractive index of each unit coating layer, i is a complex number, κ Represents a damping coefficient)], and each unit is obtained from a function consisting of a phase shift due to a refractive index attenuation coefficient κ, a phase shift at a film interface, a dispersion of a refractive index, and a peak shift depending on a particle shape. The actual thickness of each unit coating layer is corrected so that the coating layer has the interference reflection peak or the interference transmission bottom of the specific wavelength.

A feature of the heat-resistant coating composition of the present invention is that a pigment colored by providing a plurality of light interference multilayer coatings having different refractive indexes on the surface of the powder core particles has a refractive index of each layer of the multilayer coating. If the film thickness does not change, the color does not change and the refractive index of each layer and the temperature change of the film thickness are small, so that the paint containing the pigment does not change its color up to a high temperature and has a high temperature of 350 ° C or more and 600 ° C or less. In this case, a stable color tone is maintained. Further, the paint containing the pigment of the present invention does not change the color tone of the pigment because the refractive index and the thickness of each layer of the multilayer coating of the pigment do not change even when exposed to sunlight for a long period of time.

In order for the pigment powder used in the heat-resistant coating composition of the present invention to be heat-resistant, the powder core particles and the light interference multilayer coating covering the surfaces of the powder core particles must be maintained at high temperatures. It is necessary that they do not deform and discolor even if they are placed for a period of time. In order to prevent the resin from being deformed in a high temperature state, it is necessary to prevent the resins listed as the organic substances from being deformed by crosslinking or the like. Further, it is desirable that the material is stable so that the material is not decomposed or deteriorated without cross-linking.
Examples of such a preferable resin include a pure silicon resin, a fluororesin, or a silicon-modified resin. Also,
As the powder core particles, those having a specific gravity of less than 1.0 and which are not deformed or discolored even after being placed in a high temperature state for a long period of time, preferable among them are inorganic particles such as shirasu balloons (hollow silicate particles). Hollow particles, micro carbon hollow spheres (Crecus sphere), silica micro hollow spheres, calcium carbonate micro hollow spheres, and the like. Examples of the resin include a phthalic imide resin. The volumetric thermal expansion coefficient of the refractory powder core particles is of the order of 10 ^-4 / K ^-1, volumetric thermal expansion coefficient of the heat-resistant organic coating ^10-4 /
On the order of K ^-1, also volumetric thermal expansion coefficient of the inorganic coating is of the order of 10 ^-5 / K ^-1, and the thermal expansion of the powder core particle and each layer of the coating is a relative change The color of the pigment colored by providing the light interference multilayer coating does not change depending on such a change in the dimension.

The heat-resistant coating composition of the present invention is obtained by providing a medium (vehicle), a solvent, a drying accelerator, etc., by coloring a pigment obtained by providing a plurality of optical interference multilayer films having different refractive indexes on the surface of powder core particles. Mix to form a coating composition. The heat-resistant medium (resin) used in the heat-resistant coating composition of the present invention includes:
In addition to pure silicon resin and fluororesin, alkyd resin, epoxy resin, urethane resin, acrylic resin, melamine resin and other resins used for general paints are modified with silicon to have heat resistance. The solvent used for the heat-resistant coating composition of the present invention can be a solvent used for general coatings, and is not particularly limited. Solvents usually used for paints include benzene, toluene, xylene,
Hydrocarbon solvents such as n-hexane, cyclohexane, benzine and kerosene; alcohol solvents such as methanol, ethanol, isopropanol and butanol; ketone solvents such as acetone, MEK and methyl isobutyl ketone; methyl acetate, ethyl acetate and butyl Ester solvents such as acetate can be used. Further, examples of the drying accelerator include lead octylate, a silane coupling agent, a titanium coupling agent, and the like.

As a method for forming a light interference multilayer film on the surface of the powder core particles, the following methods can be mentioned depending on the substance to be formed. (1) When forming an organic film (resin film) a. Polymerization method in liquid phase By dispersing core particles and performing emulsion polymerization,
A method of forming a resin film on the particles can be used. Further, an in-situ polymerization method can be used. However, it will be difficult to use a polymerizable organic film for the heat-resistant pigment of the present invention. b. As a film forming method in a gas phase, a chemical vapor deposition method (C
VD) or physical vapor deposition (PVD).

(2) When an inorganic metal compound film is formed a. Solid phase deposition method in liquid phase A method of dispersing particles serving as nuclei in a metal alkoxide solution and hydrolyzing the metal alkoxide to form a metal oxide film on the particles is preferable. An oxide film can be formed. A method for producing a multilayer metal oxide coating powder by this method is disclosed in
8604 and JP-A-7-90310. Metal alkoxides include zinc, aluminum, cadmium, titanium, zirconium, tantalum,
An alkoxide of a metal corresponding to a required metal oxide such as silicon is selected. The powder on which the metal oxide film is formed is taken out of the solution and dried to obtain a strong metal oxide film. Drying is preferably performed under vacuum. In the case where the inorganic powder is core particles, heat treatment is further performed at 200 to 800 ° C. for 0.5 to 6 hours in a vacuum or an inert atmosphere.
A more robust film is preferable.

A metal oxide film is formed on the particles on which the metal oxide film has been formed by using a strong hydrolyzing agent such as caustic alkali, ammonia or urea (using a metal salt which is less expensive than metal alkoxide). The metal hydroxide or metal oxide can be precipitated around the powder particles by the above method. In such a case, another method of depositing a metal oxide film on the surface of powder particles is a metal such as titanium sulfate or zircon sulfate that is decomposed by heating to deposit titanium oxide or zircon oxide. Using the salt as a raw material, immersing the powder particles in an aqueous solution of these metal salts,
The coating film can be formed by heating and decomposing to deposit a metal oxide film around the powder particles. b. Film Formation Method in Gas Phase (CVD) (PVD) A thin film of a metal oxide or the like can be formed by a known chemical vapor deposition method or physical vapor deposition method.

(3) When forming a metal film or an alloy film a. Method of Reducing Metal Salt in Liquid Phase A so-called chemical plating method of reducing a metal salt in an aqueous solution of a metal salt to deposit a metal to form a metal film is used. b. Film formation method in gas phase (CVD) (PVD) A metal film can be formed on the surface of particles by vacuum evaporation of metal or the like. Further, it can be provided by a sputtering method. However, the sputtering method has a disadvantage that the powder is not uniformly irradiated with the metal vapor, and the thickness of the coated powder differs for each powder.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, as an example, a method for forming an alternate multilayer film of a metal oxide having a high refractive index and a metal oxide having a low refractive index will be specifically described. First, as a method of forming a metal oxide film having a high refractive index, powder core particles are dispersed in an alcohol solution in which an alkoxide such as titanium or zirconium is dissolved, and a mixed solution of water, alcohol, and a catalyst is stirred while stirring. By dropping and hydrolyzing the alkoxide, a titanium oxide film or a zirconium oxide film is formed as a high refractive index film on the surface of the powder core particles. Thereafter, the powder is subjected to solid-liquid separation, dried and then subjected to a heat treatment. As drying means, vacuum heating drying, vacuum drying,
Any of natural drying may be used. Further, it is also possible to use a device such as a spray dryer in an inert atmosphere while adjusting the atmosphere. In the heat treatment, a coating composition that does not oxidize is placed in air, and a coating composition that is easily oxidized is placed in an inert atmosphere.
0 to 1100 ° C (when the powder core particles are inorganic powder) or 150 to 500 ° C (when the powder core particles are other than inorganic powder)
For 1 minute to 3 hours.

Subsequently, as a method for forming a metal oxide film having a low refractive index, the powder having the high refractive index film is dispersed in an alcohol solution in which silicon alkoxide or aluminum alkoxide is dissolved, and the mixture is stirred. A mixed solution of water, an alcohol and a catalyst is added dropwise to the mixture while the alkoxide is hydrolyzed to form a silicon oxide or aluminum oxide film as a low refractive index film on the surface of the powder core particles. Thereafter, the powder is subjected to solid-liquid separation, dried under vacuum, and then subjected to heat treatment in the same manner as described above. By this operation, a powder having two layers of a high-refractive-index metal oxide film and a low-refractive-index metal oxide film on the surface of the powder core particles is obtained. FIG.
1 is a sectional view showing a conceptual structure of a pigment powder of the present invention, wherein powder core particles 1 having a specific gravity of 0.1 to 2.8 are used as nuclei, and two coating films having different refractive indexes are formed on the surface thereof. The layers 2 and 3 are provided alternately, and four layers are provided.

A special function can be provided by adjusting the thickness of each layer of the alternating coating film having a different refractive index formed on the surface of the powder core particles of the present invention. For example, an alternating coating film having a different refractive index is formed on the surface of the powder core particles so that the following formula (I) is satisfied, the refractive index n of the material forming the coating film and a quarter of the wavelength of visible light. When an appropriate thickness and the number of the alternating films having a thickness d corresponding to an integer m times as large as are provided, light having a specific wavelength λ (using interference reflection of Fresnel) is reflected or absorbed. nd = mλ / 4 (I) By utilizing this action, an oxide film having a film thickness and a refractive index that satisfies the formula (I) with respect to a target wavelength of visible light on the surface of the powder core particles. Is formed, and coating with an oxide film having a different refractive index is alternately repeated once or more, thereby forming a film having a reflection or absorption wavelength width specific to the visible light region. At this time, the order of the materials to be formed is determined as follows. First, when the refractive index of a core organic substance is high, the first layer is a film having a low refractive index,
In the case of the opposite relationship, the first layer is preferably a film having a high refractive index.

The film thickness is measured and controlled as a reflection waveform using a spectrophotometer or the like to measure and control the change in the optical film thickness, which is the product of the film refractive index and the film thickness. The thickness of each layer is designed. For example, as shown in FIG. 2, when the peak positions of the reflection waveform of each unit film are precisely adjusted, a single colored powder such as blue, green, and yellow can be obtained without using a dye or a pigment.

However, in the case of an actual powder, the particle size of the powder,
It is necessary to design in consideration of the shape, the phase shift at the interface between the film material and the nuclear particle material, and the peak shift due to the wavelength dependence of the refractive index. For example, when the shape of the core particle is a parallel plate, the Fresnel interference by the parallel film formed on the particle plane is obtained by replacing n in the above formula (I) with the following formula (II).
The design is performed under the condition that N is replaced. In particular, when the metal film is included even when the shape of the powder is a parallel plate,
The damping coefficient κ is included in the refractive index N of the metal of the formula (II). In the case of a transparent oxide (dielectric), κ is very small and can be ignored. N = n + iκ (i represents a complex number) (II) If this damping coefficient κ is large, the phase shift at the mutual interface between the film material and the nuclear particle material becomes large, and all the layers of the multilayer film are caused by the phase shift. Affects the interference optimum film thickness.

As a result, even if only the geometrical film thickness is adjusted, the peak position shifts, so that the color becomes lighter, especially when colored in a single color. In order to prevent this, the effects of the phase shift on all the films are taken into consideration, and a computer simulation is designed so that the combination of the film thicknesses is optimized in advance. Further, there is a phase shift due to the oxide layer on the metal surface and a peak shift due to the wavelength dependence of the refractive index. In order to correct these, it is necessary to find an optimal condition using a spectrophotometer or the like so that the reflection peak or the absorption bottom becomes the target wavelength in the final target film number.

The interference of a film formed on a curved surface such as a spherical powder occurs similarly to a flat plate, and basically follows the Fresnel interference principle. Therefore, the coloring method can be designed to be a single color as shown in FIG. However, in the case of a curved surface, light incident on and reflected by the powder causes complicated interference. These interference waveforms are almost the same as a flat plate when the number of films is small. However, as the total number increases, the interference inside the multilayer film becomes more complicated. Also in the case of a multilayer film, the reflection spectral curve can be designed in advance by computer simulation based on the Fresnel interference so that the combination of the film thickness is optimized. In particular, in the case of forming a film on the surface of the powder core particles, the effect of the phase shift on the surface of the powder core particles and all the films is taken into consideration, and a computer simulation is designed to optimize the combination of film thickness in advance.

When the coating composition of the present invention is applied to an object to be coated, the relationship between the pigment and the content of the medium in the coating composition is 1: 0.5 to 1:15 by volume ratio. . If the content of the medium is too small, the applied film does not adhere to the object to be coated. On the other hand, if the amount is too large, the color of the pigment becomes too light and cannot be said to be a good paint. The relationship between the amount of the solvent and the total amount of the pigment and the medium in the coating composition is 1: 0.5 to
When the amount of the solvent is too small, the viscosity of the paint is too high to be applied uniformly. On the other hand, if the amount of the solvent is too large, it takes time to dry the coating film, and the efficiency of the coating operation is extremely reduced.

Further, the color density of the coating film when the coating material is applied to the object to be coated is determined by the amount of pigment per unit area of the object to be coated. When the amount of the pigment coated with the multilayer film of the present invention on the object to be coated after the coating is dried is 10 to 150 g per square meter in area density, a good coating color can be obtained. If the area density is smaller than the above value, the background color of the object to be coated appears, and if the area density is larger than the above value, the color density of the coating color does not change, which is uneconomical. That is, even if the pigment is placed on the object to be coated with a certain thickness or more, the light does not reach the pigment on the lower side of the coating film. It is uneconomical to make the coating film thicker than such a thickness, because the coating thickness exceeds the hiding power of the coating material, so that the coating effect is not obtained. However, considering the wear of the coating film,
This is not the case when thick coating is performed because the thickness of the coating film is reduced.

[0032]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only this embodiment.

Example 1 (Production method of red-purple multilayer film-coated powder) First layer: 10 g of silica-coated magnetite powder (average particle size: 1.2 μm) was dispersed in 100 ml of ethanol. 6 g of silicon ethoxide powder and 8 g and 8 g of 29% aqueous ammonia were added to this,
The reaction was performed for 5 hours while stirring. After the reaction, the reaction solution was diluted with ethanol, filtered, and dried in a vacuum drier at 110 ° C. for 8 hours.
After drying, heat treatment was performed at 650 ° C. for 30 minutes in a nitrogen atmosphere using a rotary tube furnace to obtain silica-coated powder A. The thickness of the obtained silica-coated powder A was 75 nm, and the dispersion state was very good. This silica-coated powder A was heat-treated.

Second layer: titania silica coating 10 g of the obtained silica-coated powder A was mixed with ethanol 2
2. Add 00 ml and disperse, and add titanium ethoxide
Add 5 g and stir. To this, a mixed solution of 30 ml of ethanol and 3.5 g of water was dropped over 60 minutes, and the mixture was reacted for 5 hours, subjected to vacuum drying and heat treatment in the same manner as in the first layer to obtain silica titania-coated powder B. The obtained silica titania-coated powder B had good dispersibility, and each was a single particle. This silica titania-coated powder B had a titania film thickness of 55 nm.

Third layer: Silica coating 10 g of silica titania-coated powder B is added to 100 parts of ethanol.
Dispersed in ml. Add 6g of silicon ethoxide and 2
11 g of 9% aqueous ammonia and 8 g of water were added and reacted for 5 hours with stirring. After the reaction, the reaction mixture was diluted with ethanol, washed, filtered, and dried for 8 hours in the same manner as the first layer. After drying,
Heat treatment was performed at 650 ° C. for 30 minutes using a rotary tube furnace to obtain silica-coated powder C. The thickness of the obtained silica-coated powder C was 78 nm, and the dispersion state was very good.

Fourth layer: titania silica coating 10 g of the obtained silica-coated powder C was mixed with ethanol 2
2. Add 00 ml and disperse, and add titanium ethoxide
Add 8 g and stir. A mixed solution of 30 ml of ethanol and 3.8 g of water was added dropwise thereto over 60 minutes, and the mixture was reacted for 5 hours, and subjected to vacuum drying and heat treatment in the same manner as in the first layer to obtain silica titania-coated powder D. The obtained silica-titania-coated powder D had good dispersibility and each was a single particle. This silica titania-coated powder D had good dispersibility, and each was a single particle. The thickness of the fourth titania film was 57 nm. -Characteristics of pigment powder The multilayer coating powder thus obtained has a reflection peak of 40% at 380 nm and 45% at 780 nm.
It was a vivid reddish purple. Further, the magnetization of this powder at 10 Oe was 153 emu / g.

(Preparation of heat-resistant paint) To 50 parts by weight of pure silicone resin, 30 parts by weight of the above-obtained red-purple multi-layer coating powder was added, and 50 parts by weight of benzene were further added, kneaded and homogenized to obtain a coating composition. I got something. The obtained coating composition was applied to an alumina ceramic plate. After coating, the coating was dried, and the thickness of the obtained coating film was 12 μm. The painted plate was purplish red. When the absorption wavelength of this coated plate was measured with a spectrophotometer, the peak wavelength was 770 nm and the reflectance was 48.
%Met. Further, the coated plate was heated at 500 ° C and 200 ° C.
After holding in an oxygen atmosphere for a time, the coated plate was cooled and the absorption wavelength was measured with a spectrophotometer.
It was 68 nm, the reflectance was 49%, and there was almost no change.

[0038]

As described above, according to the present invention,
Even without using conventional dyes and pigments, a colored coating composition can be obtained.
A coating film that does not discolor or fade even at the following high temperatures is obtained. In particular, in the present invention, even when using powder core particles of various materials that do not cause deformation or coloring at a high temperature of 350 ° C. or more and 600 ° C. or less, by providing a light interference multilayer coating on the particles. Having a color different from the powder core particles,
In addition, since a pigment whose color does not change due to heat is used, a heat-resistant coating composition whose color does not change due to high temperatures is provided, whereby a heat-resistant coating film can be easily formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a conceptual structure of a pigment powder used for a heat-resistant paint of the present invention.

FIG. 2 is a graph showing a spectral waveform of the reflection intensity of each unit film constituting a multilayer film of a single-colored powder.

[Explanation of symbols]

 1 powder core particles 2 coating layer 3 coating layer

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // B05D 5/00 B05D 5/00 E

Claims (4)

[Claims] 1. A pigment made of a powder having a plurality of light interference multilayer films having different refractive indices on the surface of powder core particles of a material which does not cause deformation or coloring at a high temperature of 350 ° C. or more and 600 ° C. or less. A heat-resistant coating composition comprising a solvent solution of a vehicle that provides a coating film or a solvent-dispersed solution together with a vehicle. 2. The heat-resistant coating composition according to claim 1, wherein at least one layer of the light interference multilayer coating of the pigment is an inorganic metal compound layer. 3. The light interference multilayer coating according to claim 1, wherein at least one of the optical interference multilayer coatings is a metal layer or an alloy layer.
The heat-resistant coating composition as described in the above. 4. The vehicle according to claim 1, wherein the vehicle is at least one selected from a pure silicone resin, a fluororesin, and a silicon-modified resin.
The heat-resistant coating composition according to claim 1, comprising one resin.