JP2001040243A - Magenta-colored powder and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magenta-colored powder capable of being produced by an inexpensive and safe method without using an expensive raw material and dangerous organic solvent by forming a specific coating film on the surface of substrate particles. SOLUTION: This magenta-colored powder is obtained by forming a coating film whose at least one layer is formed on the surface of each of substrate particles through reaction of a metal salt in an aqueous solvent and which gives a reflection spectrum having peaks at 350-450 nm and 700-850 nm and a bottom at 450-650 nm. It is preferable that the coating film formed through reaction of the metal salt in the aqueous solvent satisfies the formula Nd=mλ/4 [N=n+iκ (n is the refractive index of a substance constituting the film; i is a complex number; κ is a damping coefficient) ;d is a film thickness; m is a natural number; λ is each of peak wavelengths of the reflection spectrum given by the powder, 350-450 nm and 700-850 nm].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magenta color powder and a method for producing the same, and more specifically, to produce it by an inexpensive and safe method without using an expensive raw material or a dangerous organic solvent. The present invention relates to a magenta colored powder that can be used for various purposes such as ink, filler for plastic/paper, toner, ink for inkjet printer, and a method for producing the same.

[0002]

2. Description of the Related Art The present inventors have previously used powder particles as a base material in order to provide a powder having not only the properties that only one powder particle has but also another property and having a composite function. As a result, the inventors invented a powder having a metal oxide film or the like with a uniform thickness of 0.01 to 20 μm on the surface thereof (Japanese Patent Laid-Open No. H06-69242).
-228604 publication). Further, the present inventors have further improved the above-mentioned powder, and invented not only the metal oxide film but also a powder having a plurality of layers of the metal oxide film and the metal film alternately (see Japanese Patent Application Laid-Open No. Hei 7 (1999)-58). -90310).

In order to produce these powders, it is necessary to provide a plurality of metal oxide films having a uniform thickness on the surface of the substrate. For that purpose, the metal oxide or its precursor is prepared from the aqueous solution of the metal salt. Since it is difficult to precipitate the metal compound which is the body, the present inventors have dispersed the above-mentioned substrate in a metal alkoxide solution and hydrolyzed the metal alkoxide to form a metal oxide film on the substrate. By developing a method for producing the metal oxide film, it becomes possible to form a thin metal oxide film having a uniform thickness, and in particular, it becomes possible to form a multilayer metal oxide film. In addition, the inventors of the present invention control the combination of substances of the multilayer film, the refractive index, and the film thickness of the powder having a multilayer film coating such as a metal oxide film on the surface of the powder particles as a base. It was found that by adjusting the reflected light interference waveform of the multilayer film, a colored powder such as a pigment can be obtained (WO96/2).
8269).

Further, the inventors of the present invention have based on the above-mentioned technology.
An attempt was made to establish a technique for obtaining a colored powder having a desired specific color tone, specifically, a condition range for developing the color of a film-coated powder exhibiting a bright magenta color. For example, magenta is one of the three primary colors of light,
It is also an important pigment that gives a person a psychological warmth, stimulus, and glitz. It is of great industrial significance to obtain a pigment powder having a magenta color tone and a specific function. As a result of study from such a viewpoint, the present inventors formed a plurality of coating films in which a coating film having a large refractive index and a coating film having a small refractive index are laminated next to each other on the surface of the substrate particles, and the coating film having a thickness of 350 to 450 nm And a peak between 700 and 850 nm, and between 450 and
It was found that a magenta-colored powder can be obtained by setting the conditions of the base particles and the coating film so as to show a reflection spectrum having a bottom between 650 nm (Japanese Patent Laid-Open No. 11-21467). ..

[0005]

However, in the magenta colored powder described in JP-A-11-21467, the coating layer on the surface of the base particles is formed by the hydrolysis reaction of the metal alkoxide. Met.
In the film formation method by the hydrolysis reaction of metal alkoxide, it is necessary to use an organic solvent having high flammability as a solvent and an expensive metal alkoxide as a raw material. In order to use the highly flammable organic solvent, the manufacturing facility must be an explosion-proof facility and the temperature and humidity must be controlled strictly, and the price of the product manufactured using it becomes naturally expensive. Further, the magenta colored powder described in JP-A No. 11-21467 does not have sufficient brightness and has a dark color tone.

Therefore, an object of the present invention is to overcome the above-mentioned drawbacks of the prior art and to use a manufacturing facility without using a method by hydrolysis of a metal alkoxide, without using an expensive metal alkoxide or a highly flammable organic solvent. It is also an object of the present invention to provide a highly functional magenta color powder and a method for producing the same, which does not require explosion-proof equipment, can be easily controlled in temperature and humidity, and can be obtained at a low price overall. A further object of the present invention is to provide a bright magenta colored powder having sufficient brightness and a method for producing the same.

[0007]

[In the formula, N=n+iκ (i represents a complex number) n: Refractive index of a substance forming a film d: Film thickness m: Natural number λ: Peak wavelength of a reflection spectrum of powder (where λ is 350 ˜450 nm and 700-850 nm) κ: attenuation coefficient]

(3) The magenta powder as described in (1) above, wherein the coating film on the surface of the base particles is a multilayer film. (4) The magenta powder as described in (3) above, wherein each of the multilayer films is formed by a reaction of a metal salt in an aqueous solvent. (5) The magenta colored powder according to (3), wherein each of the multilayer films satisfies the condition of the following formula. Nd=mλ/4 [In the formula, N=n+iκ (i represents a complex number) n: Refractive index of the substance constituting the film d: Film thickness m: Natural number λ: Peak wavelength of the reflection spectrum of the powder ( However, λ is 350 to 450 nm and 700 to 850.
nm) κ: attenuation coefficient]

(6) At least one layer of the coating film on the surface of the base particles is constituted as an aggregate of crystallized fine particles having voids, (1)
Magenta powder as described. (7) The coating film formed as an aggregate of crystallized fine particles having voids is capable of imparting lightness by scattering and reflection of light generated between the surface of the crystallized fine particles and voids. The magenta colored powder according to (6) above. (8) A dense coating film composed of ultrafine particles capable of closing the voids on the surface is provided on the surface of the coating film formed as an aggregate of crystallized fine particles having voids. The magenta colored powder according to (6) above. (9) The magenta colored powder as described in (6) above, wherein the coating film formed as an aggregate of crystallized fine particles having voids is a high refractive index film. (10) The magenta powder according to (8), wherein the dense film is a silica film.

(11) The coating film formed as an aggregate of crystallized fine particles having voids forms solid phase fine particles in a reaction solution for forming the coating film, and the solid phase fine particles are formed. The magenta colored powder as described in (6) above, which is formed by firing after being incorporated into the coating film. (12) The magenta colored powder as described in (11) above, wherein the reaction solution is an aqueous solution. (13) Before the firing, the coating film in which the solid phase fine particles are incorporated is coated with ultrafine particles capable of forming a dense film that closes voids on the surface of the coating film. (11) The magenta colored powder as described in (11) above.

(14) In the method for producing a magenta powder by forming a coating film on the surface of base particles, the obtained powder has a particle size of 350 to 450 nm and 700 to 850 nm.
Characterized in that at least one layer of the coating film is formed by reaction of a metal salt in an aqueous solvent so as to exhibit a reflection spectrum having a peak between 2 and a bottom between 450 and 650 nm. And a method for producing magenta powder. (15) The method for producing magenta colored powder according to (14) above, wherein the coating film formed by the reaction of the metal salt in an aqueous solvent is formed so as to satisfy the condition of the following formula. Nd=mλ/4 [In the formula, N=n+iκ (i represents a complex number) n: Refractive index of the substance constituting the film d: Film thickness m: Natural number λ: Peak wavelength of the reflection spectrum of the powder ( However, λ is 350 to 450 nm and 700 to 850.
nm) κ: Attenuation coefficient] (16) The method for producing magenta colored powder according to (14), wherein the coating film formed on the surface of the base particles is a multilayer film. (17) Each of the multilayer films is formed by a reaction of a metal salt in an aqueous solvent, (16)
A method for producing the magenta powder as described. (18) The method for producing magenta colored powder according to (16) above, wherein each of the multilayer films is formed so as to satisfy the condition of the following formula. Nd=mλ/4 [In the formula, N=n+iκ (i represents a complex number) n: Refractive index of the substance constituting the film d: Film thickness m: Natural number λ: Peak wavelength of the reflection spectrum of the powder ( However, λ is 350 to 450 nm and 700 to 850.
nm) κ: attenuation coefficient]

(19) At least one layer of the coating film formed on the surface of the base particles is constituted as an aggregate of crystallized fine particles having voids, which is the magenta colored powder described in (14). Production method. (20) The coating film, which is formed as an aggregate of crystallized fine particles having voids, is formed so that lightness can be imparted by scattering and reflection of light generated between the surface of the crystallized fine particles and voids. A method for producing a magenta colored powder according to (19) above. (21) A dense film of ultrafine particles capable of closing the voids on the surface is formed on the surface of the coating film formed as an aggregate of crystallized fine particles having voids. (19) A method for producing the magenta powder as described. (22) The method for producing magenta colored powder as described in (19) above, wherein the coating film formed as an aggregate of crystallized fine particles having voids is a high refractive index film.

(23) The method for producing magenta colored powder according to the above (21), characterized in that the dense film is a silica film. (24) Solid phase fine particles are formed in a reaction solution for forming the coating film, and the solid phase fine particles are formed into the coating film, which is formed as an aggregate of crystallized fine particles having voids. The method for producing magenta colored powder according to the above (19), characterized in that it is formed by incorporating it into the interior and firing it. (25) The method for producing magenta colored powder as described in (24) above, wherein the reaction solution is an aqueous solution. (26) Before the firing, the coating film in which the solid phase fine particles are incorporated is coated with ultrafine particles capable of forming a dense film that closes voids on the surface of the coating film. (24) The method for producing magenta colored powder according to (24) above.

The magenta colored powder of the present invention is capable of suppressing the precipitation of a solid phase that does not form a film during the film-forming reaction by the following operations and actions, thereby forming a film having a uniform thickness on the surface of the substrate particles. It can be formed with a thickness of.
By using a buffer solution as the reaction solvent and adjusting the pH to a certain level, the effect of acid or alkali is moderated,
Corrosion of the substrate surface is prevented; ultrasonic dispersion not only improves the dispersibility of the substrate particles, especially the magnetic substance such as magnetite powder, but also improves the diffusibility of the coating components.
Prevents the adhesion of the coatings to each other and improves the dispersibility of the coated magnetic particles; suppresses the precipitation of solid phase that does not form a coating by precipitating the coating components at an appropriate reaction speed. Due to the above-mentioned comprehensive action, the electric charge on the surface of the film-coated powder can be kept constant, and the function of the electric double layer can provide dispersed particles without aggregation of the film-coated powder. In order to make the best use of the function of the electric double layer, the pH differs depending on the combination of the substance of the substrate and the kind of the metal compound formed in the liquid by the film forming reaction, and it is preferable to avoid the isoelectric point of both. Further, at least one layer of the coating film on the surface of the base particles is a film composed of an aggregate of crystallized fine particles and crystallized fine particles having voids between the crystallized fine particles (hereinafter, simply referred to as a crystallized fine particle constituent film By increasing the refractive index difference between the surface of the crystallized fine particles and the voids, scattering reflection of light is caused, the reflection effect is enhanced, and a functional powder of magenta color tone having excellent brightness is provided. It became possible to do.

According to the present invention, due to the above mechanism of action, despite the use of the water-soluble raw material, the film-coated powders do not agglomerate or stick to each other even when the magnetic substance is used as the substrate, and preferable film thickness control It was possible to easily produce a film-coated powder capable of Further, by using water as a solvent, it is possible to obtain an effect that a film can be formed at a lower manufacturing cost than the alkoxide method.

FIG. 1 is a cross-sectional view of an example of the magenta colored powder of the present invention having a crystallized fine particle constituting film 2 on the surface of a base particle 1, and FIG. 2 is a crystal of the magenta colored powder of FIG. FIG. 3 is an enlarged cross-sectional view of a film 2 for forming fine particles. 1 and 2
As shown in FIG. 3, the crystallized fine particle constituting film 2 has voids between the crystallized fine particles 3 so that
The difference in refractive index between the surface and the voids is increased to cause light scattering and reflection, whereby a powder having high brightness can be obtained. The stronger the scattering reflection is, the more light the powder is. It is preferable that the crystallized fine particles 3 contained in the film 2 have a high refractive index and that the particle diameters are not uniform. The brightness can be adjusted by the amount and particle size of the crystallized fine particles in the film. However, depending on the particle size, scattering and interference may occur at the same time, and due to the interference, a hue other than magenta may be exhibited, so caution is required in its design. In particular, when the obtained film-coated powder has a strong monochromatic spectrum color like opal, the crystallization particle size in the film is uniform at a certain size (about 1/4 to 1 wavelength of light wavelength). Therefore, it is considered that the crystallized fine particles cause interference.

In this case, the particle diameter of the crystallized fine particles in the film is preferably 1 to 500 nm, more preferably 1 to 2
00 nm, and more preferably in the range of 1 to 100 nm. If the particle size is less than 1 nm, the color of the underlying substrate particles may appear as it is, even if it becomes a film, because it transmits light. On the other hand, when it is larger than 500 nm, the interference coloring occurs due to the reflected light of a plurality of particles, or the film becomes brittle and peels off easily, which is not preferable. Further, the crystallized fine particles in the film can be distinguished by the shape such as grain boundaries even if they are in contact with other fine particles or the film.

On the other hand, one layer of the above-mentioned crystallized fine particle constituent film,
The preferred thickness range depends on the size of the base particles. 0.05 μ when the base particles are 0.1 μm to 1 μm
.mu.m to 0.5 .mu.m and the substrate particles are 1 .mu.m to 10 .mu.m, the value of 0.
05 μm to 2 μm, 0.0 when the substrate particles are 10 μm or more
It is preferably 5 μm to 3 μm. Further, the preferable thickness range of the total film thickness of the crystallized fine particle constituent film also differs depending on the size of the particles serving as the substrate. Base particle is 0.1μ
m-1 μm, 0.1 μm-3 μm, base particles 1 μm
10 μm to 0.1 μm to 5 μm, the base particles are 10 μm
When it is m or more, it is preferably 0.1 μm to 10 μm.

Further, as shown in FIG. 2, the magenta colored powder of the present invention has ultrafine particles 4 capable of closing the voids on the surface of the film 2 composed of the crystallized fine particles 3 having voids. It is preferable to have a dense coating film (hereinafter also simply referred to as a dense film) configured by. For example, when magenta powder having the above-described crystallized fine particle constituent film as the outermost layer is used as a pigment powder such as toner or paint, the resin of the toner or the vehicle of the paint penetrates into the voids and crystallized fine particles are generated. The difference in the refractive index between the surface of 3 and the voids is reduced to weaken the scattered reflection of light, and as a result, the brightness is also reduced. The dense film described above is suitable for preventing the decrease in brightness as described above.

Japanese Patent Application Laid-Open No. 4-269804 discloses a colored powder having a coating layer of inorganic pigment particles on the surface.
It is filled with a mixture of a surface treatment agent and a resin, and unlike the magenta colored powder of the present invention, it does not cause scattered reflection and is colored in a desired color by the color of the pigment particles themselves. is there. Moreover, this Japanese Patent Laid-Open No. 4-26
In the colored powder described in Japanese Patent Publication No. 9804, the pigment particles may not be sufficiently fixed on the surface of the base particles. In that case, the pigment particles adhering to the substrate are separated in the mixed liquid of the solvent and the resin, so that they may not be applicable to paints and the like.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The magenta colored powder of the present invention will be described in detail below. The magenta powder of the present invention is a multilayer film-coated powder which further has, on the surface of the base particles, not only the above-mentioned crystallized fine particle constituting film but also a film having another structure capable of transmitting light. As the light-transmitting coating film having a low refractive index, when the metal hydroxide film or the metal oxide film is formed into a plurality of layers by the reaction of a metal salt or the like, the above-mentioned coating film (coating the base particles , The layer of the membrane involved in light interference)
A special function can be given by adjusting the thickness of each layer. For example, on the surface of the base particles, an alternating coating film having a different refractive index is provided so that the refractive index n of the substance forming the film is between 350 and 450 nm and between 700 and 850 nm so as to satisfy the following formula (1). If an alternate film having a thickness d corresponding to an integer m times a quarter of the wavelength of visible light is provided with an appropriate thickness and number of films, wavelengths λ between 350 and 450 nm and between 700 and 850 nm are obtained. Light (using Fresnel interference reflection) is reflected or absorbed. nd=mλ/4 (1)

Utilizing this action, the surface of the substrate particles is targeted to a region of 350 to 450 nm and 700 to 850 nm.
For a wavelength between nm, a film having a film thickness and a refractive index satisfying the formula (1) is formed, and a film having a different refractive index is further coated thereon once or more times. By repeating the above, a film having a reflection peak between 350 and 450 nm and between 700 and 850 nm is formed. At this time, the order of the materials for film formation is determined as follows. First, when the refractive index of the core substrate is high, the first layer is preferably a film having a low refractive index, and in the opposite case, the first layer is preferably a film having a high refractive index.

The film thickness is measured by controlling a change in optical film thickness, which is a product of film refractive index and film thickness, as a reflection waveform with a spectrophotometer or the like. Design the film thickness of each layer. For example, if the peak position of the reflection waveform of each unit coating constituting the multilayer film is precisely adjusted to the range of 350 to 450 nm and the range of 700 to 850 nm,
A magenta monochromatic colored powder can be obtained without using a dye or pigment.

However, in the case of an actual substrate, the particle size of the substrate,
It is necessary to design considering the shape, the phase shift at the interface between the film substance and the substrate particle substance, and the peak shift due to the wavelength dependence of the refractive index. For example, when the shape of the substrate particles is a parallel plate shape, the Fresnel interference due to the parallel film formed on the particle plane is designed under the condition that n in the above formula (1) is replaced with N in the following formula (2). To do. In particular, when the metal film is included even when the substrate has a parallel plate shape, the attenuation coefficient κ is included in the refractive index N of the metal of the formula (2). In the case of a transparent oxide (dielectric), κ is very small and can be ignored. N=n+iκ (i represents a complex number) (2) If this attenuation coefficient κ is large, the phase shift at the interface between the film substance and the substrate substance becomes large, and further, interference due to the phase shift occurs in all layers of the multilayer film. Affects optimum film thickness.

As a result, the peak position shifts even if only the geometrical film thickness is adjusted, so that the color becomes light, especially when colored in the blue color system. In order to prevent this, the effect of the phase shift on all films is taken into consideration, and it is designed in advance by computer simulation to optimize the combination of film thicknesses. Furthermore, there is a phase shift due to the oxide layer on the surface of the substrate and a peak shift due to the wavelength dependence of the refractive index. To correct these, use a spectrophotometer or the like, and the reflection peak is 350 to 45, which is the target wavelength at the final target film number.
It is necessary to find the optimal conditions to be between 0 nm and in the range of 700-850 nm.

The interference of a film formed on a curved surface such as spherical powder occurs similarly to a flat plate, and basically follows the Fresnel's interference principle. Therefore, the coloring method can be designed in the magenta color system. However, in the case of a curved surface, the incident angle of light to each film, the reflection angle, the curvature of each film, etc. are different and a phase shift occurs accordingly, and the light incident on the powder and reflected is complicatedly interfered. These interference waveforms are almost the same as the flat plate when the number of films is small. However, as the total number increases, the interference inside the multilayer becomes more complicated. Also in the case of a multilayer film, the reflection spectral curve can be designed in advance by computer simulation so as to optimize the combination of film thicknesses based on Fresnel interference. In particular, in the case of forming a film on the surface of the base particles, the influence of the phase shift on the surface of the base particles and all the films is taken into consideration, and the combination of the film thicknesses is optimized in advance by computer simulation. further,
The peak shift due to the oxide layer on the surface of the base particles and the peak shift due to the wavelength dependence of the refractive index are also taken into consideration. In actual sample production, the designed spectroscopic curves are used as a reference, and in order to correct these in the actual film, the reflection peak in the spectrophotometer etc. is the target number of the final target film in the range of 350 to 450 nm and in the range of 700 to 850 nm. The optimum conditions must be found while changing the film thickness to obtain the wavelength.

Interference occurs due to the multilayer film even when the powder of irregular shape is colored, and the basic film design is carried out with reference to the conditions of the interference multilayer film of spherical powder. The peak position of each unit film forming the above-mentioned multilayer film can be adjusted by the film thickness of each layer, and the film thickness is the raw material under the coating forming conditions for forming a solid phase component such as a metal oxide on the surface of the substrate particles. By controlling the composition, the solid phase deposition rate, the amount of the substrate, and the like, the film thickness can be accurately controlled, a film having a uniform thickness can be formed, and the desired magenta color system can be colored. As described above, the reflection peak and the absorption bottom are 3 in the final target film number.
The magenta powder can be obtained by finding the optimum conditions while changing the film forming conditions such as the film forming solution so that the target wavelengths are in the range of 50 to 450 nm and 700 to 850 nm. In addition, the color development due to the interference of the multilayer film can be adjusted by controlling the combination of the substances forming the multilayer film and the film thickness of each unit film. Thereby, the powder can be vividly colored in a desired magenta color system without using a dye or a pigment.

The magenta colored powder of the present invention and the method for producing the same will be described in detail below. In the magenta colored powder of the present invention and the method for producing the same, the base particles on which the metal oxide film or the like is formed are not particularly limited,
It may be an inorganic substance containing a metal, an organic substance, a magnetic substance, a dielectric substance, a conductor or an insulator. If the substrate is metal, iron, nickel, chromium, titanium, aluminum, etc.
Although any metal may be used, when utilizing its magnetism, it is preferable to be magnetic such as iron. These metals may be alloys, and when they have the above magnetism, it is preferable to use a ferromagnetic alloy. Also,
When the powder substrate is a metal compound, typical examples thereof include the above-mentioned metal oxides. Examples include iron, nickel, chromium, titanium, aluminum, silicon and the like, calcium, magnesium. Oxides such as barium and barium, or composite oxides thereof may be used. Furthermore, examples of metal compounds other than metal oxides include metal nitrides, metal carbides, metal sulfides, metal fluorides, metal carbonates, metal phosphates, and the like.

Further, as the base particles, other than metal,
It is a semi-metal or non-metal compound, particularly an oxide, a carbide or a nitride, and silica, glass beads or the like can be used. Other inorganic substances include inorganic hollow particles such as shirasu balloon (hollow silicate particles), fine carbon hollow spheres (crecassphere), fused alumina bubbles, aerosil, white carbon, silica fine hollow spheres, calcium carbonate fine hollow spheres, Mica such as calcium carbonate, perlite, talc, bentonite, synthetic mica, muscovite, kaolin and the like can be used.

Resin particles are preferred as the organic material. Specific examples of the resin particles include cellulose powder, cellulose acetate powder, polyamide, epoxy resin, polyester, melamine resin, polyurethane, vinyl acetate resin, silicon resin, acrylic ester, methacrylic ester, styrene, ethylene, propylene and these. Examples thereof include spherical or crushed particles obtained by polymerization or copolymerization of the derivative of. Particularly preferred resin particles are spherical acrylic resin particles obtained by polymerization of acrylic acid or methacrylic acid ester.

The shape of the substrate is, for example, a sphere, a subsphere, an isotropic body such as a regular polyhedron, a rectangular parallelepiped, a spheroid, a rhombohedron, a plate, a needle (a cylinder, a prism), or another polyhedron. It is also possible to use a completely amorphous powder such as a thing. These substrates are not particularly limited in particle size,
It is preferably in the range of 0.01 μm to several mm. Also,
The specific gravity of the base particles used is in the range of 0.1 to 10.5, but in view of fluidity and floating property, it is 0.1 to 10.5.
It is preferably 5.5, more preferably 0.1 to 2.8. If the specific gravity of the substrate is less than 0.1, the buoyancy in the liquid is too large, and the film must be multi-layered or extremely thick, which is uneconomical. On the other hand, when it exceeds 10.5, the film for floating becomes thick, which is also uneconomical.

In the present invention, as described above, the powder base particles are coated with a plurality of coating layers having different refractive indexes, and the coating layers are coated by appropriately selecting the refractive index and the layer thickness. A powder that is colored magenta due to the interference color and exhibits a specific interference reflection peak in a region other than the visible light region can be obtained. As described above, the metal hydroxide film or the metal oxide film is deposited on the surface of the substrate particles by the reaction of the metal salt. However, a buffer solution is used as a solvent for the solid phase deposition reaction, and the solution is kept at a certain pH. Precipitate at an appropriate rate.

In the present invention, the metal used as the metal salt is iron, nickel, chromium, titanium, zinc, aluminum, cadmium, zirconium, silicon, tin, lead,
Other than lithium, indium, neodymium, bismuth, cerium and antimony, calcium, magnesium, barium and the like can be mentioned. Examples of salts of these metals include salts of sulfuric acid, nitric acid, hydrochloric acid, oxalic acid, carbonic acid and carboxylic acids. Furthermore, chelate complexes of the above metals are also included. The kind of the metal salt used in the present invention is selected according to the properties to be imparted to the surface of the substrate and the means applied in the production.

A film of a metal oxide or the like formed of these metal salts may be formed in a plurality of layers, and if necessary, a metal oxide or the like formed by hydrolysis of a metal alkoxide may be formed on the film of the metal oxide or the like. It is also possible to form a film by another film forming method. In this way, a multi-layered film can be formed on the base particles, and at that time, by setting the forming conditions so that the thickness of each layer has a predetermined thickness, the desired characteristics can be obtained. In addition, it is possible to obtain a multi-layered film of metal oxide or the like by using a metal salt which is an inexpensive raw material with a simple operation. In particular, it is an important advantage that a multi-layer film-coated powder can be obtained without using an expensive metal alkoxide as a raw material.

In the method for producing magenta colored powder of the present invention, the multi-layer coating film may be manufactured as a continuous process,
Further, each coating film can be manufactured by various methods such as manufacturing one layer at a time, or combining single-layer manufacturing and multi-layer continuous manufacturing. The particle size of the film-coated powder according to the present invention is not particularly limited and may be appropriately adjusted depending on the purpose, but is usually in the range of 0.01 μm to several mm.

In the present invention, the thickness of the metal oxide film formed at one time can be in the range of 5 nm to 10 μm, which can be made thicker than the conventional forming method. As the total thickness of the metal oxide film formed by dividing into a plurality of times, in the case of the color magnetic powder described above,
In order to form a metal oxide film having a high reflectance due to the interference, the range of 10 nm to 20 μm is preferable, and the range of 20 nm to 5 μm is more preferable.
The range of 0.02 to 2.0 μm is preferable for interference reflection of visible light with a particularly thin film thickness such as a limited particle size.

The magenta colored powder of the present invention is as described above.
An aqueous solvent having a constant pH is used as a film-forming reaction solvent, and at the same time, a film-coating reaction is formed by a film-forming reaction on the surface of a substrate under ultrasonic dispersion conditions. In the present invention, in order to keep the film-forming reaction constant, a buffer solution is added to an aqueous solvent to prepare a buffer solution, or a buffer solution prepared in advance is used. Further, at the time of the film forming reaction, a film raw material other than the buffer solution is added to form the film. When the film is formed by adding the film-forming raw material, if the pH changes greatly, in order to prevent this,
It is desirable to add a buffer solution. In the present invention, the constant pH means that the pH is within ±2 of a predetermined pH, preferably within ±1, and more preferably within ±0.5.

Various systems may be used for the buffer solution, and the system is not particularly limited, but first, it is important that the substrate particles can be sufficiently dispersed, and at the same time, a metal hydroxide or a metal oxide film coated on the surface of the substrate is coated. It is necessary to select the powder so that it can be dispersed by the action of the electric double layer and the condition that the dense coating film can be formed by the gentle dropping reaction described above. Therefore, the method for producing the film-coated powder of the present invention is different from the conventional method of neutralization by the reaction of a metal salt solution, deposition by the isoelectric point, or decomposition by heating to deposit.

Next, as ultrasonic dispersion conditions, various ultrasonic oscillators can be used, for example, a water tank of an ultrasonic cleaner can be used, and there is no particular limitation. However, the conditions of the ultrasonic dispersion of the present invention vary depending on the size of the oscillator, the shape and size of the reaction vessel, the amount of reaction solution, the volume, the amount of substrate particles, etc. Appropriate conditions may be selected. The buffer solution used in the present invention depends on the solid phase component to be precipitated, and is not particularly limited, but includes Tris type, boric acid type, glycine type, succinic acid type, lactic acid type, acetic acid type, tartaric acid type, hydrochloric acid. A system etc. are mentioned.

Next, as an example, a method of forming an alternating 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, when forming a film of titanium oxide or zirconium oxide, the base particles are immersed in a buffer solution of acetic acid/sodium acetate or the like and dispersed by ultrasonic oscillation, and titanium sulfate that is a metal salt of titanium or zirconium is , Zirconium sulfate or the like as a raw material, an aqueous solution of these metal salts is slowly dropped into the reaction system,
It can be carried out by depositing the produced metal hydroxide or metal oxide around the base particles. During this dropping reaction, the pH is maintained at the pH of the buffer solution (5.4). After the reaction is completed, this powder is subjected to solid-liquid separation, washed and dried, and then heat treated. Vacuum drying as the drying means,
Any of natural drying may be used. It is also possible to use a device such as a spray dryer in an inert atmosphere. In addition,
When the film to be coated is titanium oxide, the formation of titanium oxide is shown by the following reaction formula. Ti(SO ₄ ) ₂ +2H ₂ O → TiO ₂ +4H ₂ (SO
_{4) 2} TiO ₂ content of titanyl sulfate is 5 g / liter to 18
It is preferably 0 g/liter, more preferably 10 g/liter to 160 g/liter. If it is less than 5 g/l, it takes a long time to form a film, and the amount of powder to be processed is reduced, which is uneconomical. If it exceeds 180 g/l, the diluent causes hydrolysis during addition and does not become a film forming component. , Both are unsuitable.

Subsequently, when forming a film of silicon dioxide or aluminum oxide, KCl/H ₃ BO ₃
The above titania-coated particles are dipped and dispersed in a buffer solution in which NaOH is added to the system, and sodium silicate, which is a metal salt of silicon or aluminum, or aluminum chloride is used as a raw material, and an aqueous solution of these metal salts is reacted. It can be carried out by slowly dropping it into the system and depositing the produced metal hydroxide or metal oxide around the base particles. During the dropping reaction, the pH is the pH of the buffer solution.
It is held at (9.0). After the reaction is completed, this powder is subjected to solid-liquid separation, washed and dried, and then heat treated. By this operation, by repeating the operation of forming two layers of metal oxide films having different refractive indexes on the surface of the base particles, powder having a multi-layer metal oxide film on the surface thereof can be obtained. In addition,
When the film to be coated is silicon dioxide, the formation of silicon dioxide is shown in the reaction scheme below. Na ₂ Si _X O _2X+1 +H ₂ O → XSiO ₂ +2Na ⁺ +
2OH ^-

Next, the magenta colored powder of the present invention has
The crystallized fine particle constituting film may be made of any substance as long as it can scatter and reflect light and increase the brightness, but it is preferably made of a substance having a high refractive index. The substance having a high refractive index is not particularly limited, but oxides such as titanium oxide (titania), zirconium oxide, bismuth oxide, cerium oxide, antimony oxide, and indium oxide can be used, have a high refractive index, and are widely used. Most preferred is titanium oxide (titania).

As a method for forming the crystallized fine particle constituting film as described above, a method of solid phase precipitation in a film forming reaction liquid phase is used. Specifically, the inventors of the present invention have previously proposed JP-A-6-228604 and JP-A-7-903.
No. 10 and WO 96/28269, the solid phase deposition method (metal alkoxide method) by hydrolysis of metal alkoxide in an organic solvent, and the specification attached to Japanese Patent Application No. 9-298717. The solid phase precipitation method (aqueous method) by the reaction from the metal salt in the aqueous solution described in 1) and the like can be mentioned. In this case, in the film-forming reaction solution, the rate at which the solid phase fine particles are deposited in the reaction solution is higher than the rate at which the film of the deposits grows on the surface of the substrate particles (linear growth rate).
The reaction solution concentration, the added catalyst amount, and the base particle dispersion amount are adjusted. As described above, the solid phase fine particles deposited in the film forming reaction solution are adhered to the surfaces of the base particles to form a coating film composed of the solid phase fine particles.

At this point, the solid phase fine particles incorporated into the film are amorphous, voids between the solid phase fine particles are not formed, no scattering and reflection of light occurs, and the mechanical strength of the film is low. Is also very low. Therefore, the coating film composed of the solid phase fine particles is fired. By this firing, the amorphous solid phase fine particles are crystallized, and voids are also formed between the crystallized fine particles to form the crystallized fine particle constituent film that scatters and reflects the light.

In order to form the crystallized fine particle constituent film, the aqueous method is easier than the above-mentioned metal alkoxide method to make the relationship between the linear growth rate and the solid phase deposition rate preferable. Therefore, it is preferable. Further, the metal alkoxide method requires an expensive metal alkoxide as a raw material and a relatively expensive and dangerous organic solvent as a reaction solvent. For this reason, the manufacturing equipment, equipment, etc. must be explosion-proof specifications, and the cost performance becomes worse. From this point as well, the aqueous method is preferable to the metal alkoxide method.

The firing may be carried out after forming a coating film composed of the solid phase fine particles, but the coating film is further formed on the coating film as a crystallized fine particle constituting film. In that case, it is desirable from the viewpoint of the film strength of the magenta powder to be obtained that the film is coated with ultrafine particles capable of forming a dense film for closing the voids on the surface. Firing is 300
It is preferable to carry out at about 1200°C.

In the magenta colored powder of the present invention, the crystallized fine particle constituting film may have two or more layers. In that case, it is preferable that a light-transmitting coating film having a low refractive index is present between the two layers of the crystallized fine particle constituent films. The light-transmitting coating film having a low refractive index is not particularly limited, and examples thereof include those made of metal compounds, organic substances and the like.

Examples of the metal compound include metal oxides, metal sulfides, metal selenides, metal tellurides, and metal fluorides. More specifically, zinc oxide, aluminum oxide, cadmium oxide, titanium oxide,
Zirconium oxide, tantalum oxide, silicon oxide, antimony oxide, neodymium oxide, lanthanum oxide, bismuth oxide, cerium oxide, tin oxide, magnesium oxide, lithium oxide, lead oxide, cadmium sulfide, zinc sulfide, antimony sulfide, cadmium selenide, tellurium. Cadmium chloride, calcium fluoride, sodium fluoride, trisodium aluminum fluoride, lithium fluoride, magnesium fluoride and the like can be preferably used.

The method for forming the metal compound film will be described below. As a film forming method, a vapor deposition method such as a PVD method, a CVD method or a spray drying method can be used to directly deposit the particles on the surface of the base particles. However, the above-mentioned Japanese Patent Laid-Open No. 6-22 proposed by the present inventors has been proposed.
The metal alkoxide method described in 8604, JP 7-90310 A or WO 96/28269, and the aqueous method described in Japanese Patent Application No. 9-298717 are preferable. In this case, unlike the film formation of the crystallized fine particle constituent film described above, the linear growth rate is set higher than the solid phase deposition rate, and the reaction conditions are adjusted so that an amorphous uniform film is formed.

The organic substance is not particularly limited, but is preferably a resin. Specific examples of the resin include cellulose, cellulose acetate, polyamide, epoxy resin, polyester, melamine resin, polyurethane, vinyl acetate resin, silicon resin, acrylic ester, methacrylic ester, styrene, ethylene, propylene and derivatives thereof. Examples thereof include polymers and copolymers. (1) When forming an organic material film (resin film), a. A method of forming a resin film on the particles by dispersing the base particles in a liquid phase and performing emulsion polymerization (polymerization method in the liquid phase); b. Film forming method in vapor phase (CVD)
(PVD) or the like is adopted.

The following is an example of the case where the present invention is used as a magenta colored powder, and a product having a multilayer film on base particles is produced. For example, if the base particles are made of a substance having a high refractive index, a light-transmitting film having a low refractive index is provided thereon,
Further, a high-refractive-index particle constituent film is further provided thereon, and a low-refractive-index light-transmitting film is further provided thereon in sequence and alternately. If the base particles have a low refractive index, a high refractive index particle constituent film is formed thereon, a low refractive index light-transmissive film is formed thereon, and a high refractive index particle constituent film is formed thereon. And sequentially provide.

Next, the raw materials used in the present invention, particularly metal salts, will be described. As a raw material used for forming a film having a high refractive index, titanium oxide film, titanium halide, sulfate, etc., zirconium oxide film,
Zirconium halide, sulfate, carboxylate,
For cerium oxide film such as oxalate and chelate complex,
Cerium halides, sulfates, carboxylates, oxalates, etc. For bismuth oxide films, bismuth halides, nitrates, carboxylates, etc., for indium oxide films, indium halides, sulfates, etc. Etc. are preferred.
Further, as a raw material used for forming a film having a low refractive index, for a silicon oxide film, sodium silicate, water glass, a halide of silicon, an organosilicon compound such as an alkyl silicate and a polymer thereof, etc. , For aluminum oxide film,
For magnesium oxide films such as aluminum halides, sulfates and chelate complexes, magnesium sulfates and halides are preferred. In the case of a titanium oxide film, for example, mixing titanium chloride with titanium chloride has the effect of forming a rutile-type titanium oxide film having a high refractive index at a lower temperature.

A more complete oxide film can be manufactured by controlling the reaction temperature at the time of coating so that it is suitable for the type of each metal salt. When the film forming reaction (solid layer deposition reaction) on the surface of the substrate in the aqueous solvent is too slow, the reaction system can be heated to accelerate the solid layer deposition reaction. However, if the heat treatment for heating is excessive, the reaction rate is too fast, and the supersaturated solid layer does not form a film but precipitates in an aqueous solution to form gel or fine particles, which makes it difficult to control the film thickness.

After the coating film is manufactured, gradient washing is repeated while adding distilled water to remove the electrolyte, and then heat treatment such as drying and firing is performed to remove the water contained in the solid phase to completely remove the electrolyte. It is preferable to use an oxide film. Further, by heat-treating the powder after film formation in a rotary tube furnace or the like, sticking can be prevented and dispersed particles can be obtained. To form a hydroxide film or an oxide film and heat-treat it, heat treatment may be performed every time each layer is coated, or heat treatment may be performed last after the target multilayer film is completed. The heat treatment conditions vary depending on the reaction system, but the heat treatment temperature is 200 to 1,300° C., preferably 400.
~1,100°C. If the temperature is lower than 200°C, salts and water may remain, and if the temperature is higher than 1,300°C, the film and the substrate may react with each other to become another substance, both of which are unsuitable. The heat treatment time is 0.1 to 100 hours, preferably 0.5 to 50 hours.

[0054]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited by these examples. [Example 1] (Magnetization of magnetite powder particles,
Aqueous two-layer coating) (Formation of first-layer silica film) (1) Preparation of buffer solution In 1 liter of water, 0.4M potassium chloride reagent and 0.4M boric acid are dissolved to prepare buffer solution. It was set to 1. 0.4 M sodium hydroxide was dissolved in 1 liter of water to prepare buffer solution 2. 250 ml of the buffer solution 1 and 115 ml of the buffer solution 2 were mixed and homogenized to prepare buffer solution 3. (2) Aqueous sodium silicate solution (water glass solution) A sodium silicate reagent is diluted with pure water to obtain Na ₂ SiO ₃
The concentration was adjusted so that the content was 10 wt %.

(3) Silica film 50 g of spherical magnetite powder (average particle size 2.3 μm)
Was prepared in advance, buffer solution 3, 1460 m
l, and put it in a mixed solution of 500 ml of pure water, 28 kHz, 6
While applying ultrasonic waves in the 00W ultrasonic bath,
Disperse with stirring in a buffer solution containing magnetite powder. Similarly, add 400 ml (40 ml/min) of an aqueous sodium silicate solution prepared in advance,
The reaction was gradually decomposed to deposit a silica film on the surface. After the addition of the aqueous sodium silicate solution was completed, the reaction was continued for another 2 hours to react all unreacted raw materials. After the film formation reaction,
The slurry containing the silica film powder is repeatedly decanted with sufficient water and washed. After washing, the silica film-forming powder was put in a vat, separated by sedimentation, the upper liquid was discarded, and then dried in a dryer at 150° C. for 8 hours to obtain a silica-coated magnetite powder A ₁ . Obtained silica-coated magnetite powder A
_The film thickness of the silica coating film of ₁ was 71 nm.

(Formation of second layer titania film) (1) Preparation of buffer solution To 1 liter of deionized water, 0.3 M acetic acid was added.
9M sodium acetate was dissolved to give buffer solution 4. (2) Titanium Sulfate Aqueous Solution Titanium sulfate was added with water so that the concentration of TiO _{2 in} the aqueous solution was 12 g/liter, and dissolved to prepare a titanium sulfate aqueous solution.

(3) Titania Film Formation A buffer solution (700 ml) was prepared with respect to the obtained A ₁ (4.0 g), and Al was ultrasonically dispersed in the solution while thoroughly dispersing in an ultrasonic dispersion tank. While maintaining the temperature of the liquid at 50° C. to 55° C., 90 ml of an aqueous titanium sulfate solution prepared in advance was gradually added dropwise at 0.5 (ml/min). After the dropping, the reaction was continued for 3 hours to deposit the unreacted titania raw material. Then, the solid phase fine particles deposited in the liquid are fixed on the surface A ₁ of the base particle, and further, the surface is covered with the ultrafine particles having a smaller particle size than the solid phase fine particles fixed on the surface of the base particle. It was

(4) Washing and Drying After completion of the film-forming reaction, decantation was performed with pure water to remove unreacted components, excess sulfuric acid, and sulfuric acid formed by the reaction.
Solid-liquid separation was performed, and after drying with a vacuum dryer, dried powder was obtained.
The obtained dry powder is heated in a rotary tube furnace at 650° C. for 3 hours.
By performing overheat treatment (calcination) for 0 minutes, silica/titania-coated magnetite powder A ₂ having a smooth surface was obtained. The two-layer film-coated powder A ₂ had a magenta color, and its magnetization at 1 kOe was 30 emu/g. The thickness of the titania coating film of the obtained silica/titania-coated magnetite powder A ₂ was 84 n.
It was m. The reflection peak of this two-layer coating is 377 nm.
And 773 nm, and the reflectance at each peak wavelength is 4
It was 1% and 26%. Table 1 shows each refractive index, the film thickness, the peak wavelength of the spectral reflection curve of the coated powder and the reflectance at the peak wavelength of the first and second layers. Table 2 shows the measured values of the final coated powder in the L ^* , a ^* , and b ^* standard color system.

[0059]

[Table 1]

[0060]

[Table 2]

The peak wavelength of the spectral reflection curve of the coating powder of the coating film, the reflectance at that peak wavelength, the refractive index of the coating film, the film thickness and the L ^* , a ^* , b ^* standard color system. The value of was measured by the following method. 1) As for the spectral reflection curve, a powder sample was packed in a glass holder with a spectrophotometer with an integrating sphere manufactured by JASCO Corporation, and the reflected light was measured. The measuring method was according to JIS Z8723 (1988). 2) The refractive index and the film thickness were evaluated by obtaining the spectral reflection curve measurement results of the samples having different film thicknesses prepared under different conditions by fitting with the curve of the instrument calculation based on the interference equation. 3) L ^* , a ^* , and b ^* values are TC-8 manufactured by Tokyo Denshoku Co., Ltd.
Using a 600A type colorimetric color difference meter, JISZ8722 (19
The results of color measurement based on 82) are displayed in the L ^* , a ^* , b ^* standard color system defined by CIE (International Association for Certification).

[Example 2] (Magnetization of magnetite powder particles, water-based three-layer coating) (First layer silica film formation) As in Example 1, buffer solutions 1 and 2 and sodium silicate aqueous solution (water Glass solution)
Was prepared. (1) Silica film 15 g of spherical magnetite powder (average particle size 2.3 μm)
Put in 365 ml of buffer solution prepared in advance,
Ultrasonic waves are applied in an ultrasonic bath of 26 kHz and 600 W, and further dispersed in a buffer solution containing magnetite powder with stirring. Similarly, 133 ml of an aqueous sodium silicate solution (40 ml/
Min) and gradually decomposed by reaction to deposit a silica film on the surface. After the addition of the aqueous sodium silicate solution was completed, the reaction was continued for another 2 hours to react all unreacted raw materials. After the film forming reaction is completed, the slurry containing the silica film forming powder is repeatedly decanted with sufficient water and washed. After washing, put the silica film powder in a vat, settle and separate, discard the upper liquid, and then dry in a dryer at 150°C for 8 hours in air and heat treat at 300°C for 30 minutes in a nitrogen atmosphere to coat silica. Magnetite powder B ₁ was obtained.

(Second Layer Titania Film Formation) (1) Titania Film Formation In the same manner as in Example 1, the buffer solution 4 and the titanium sulfate aqueous solution were prepared and prepared in advance. Obtained B ₁ ,
To 4.0 g, 700 ml of buffer solution and 250 ml of pure water
And ultrasonically dispersing B ₁ in the solution, thoroughly dispersing in an ultrasonic dispersion tank, and then maintaining the temperature of the solution at 60° C., which was prepared in advance. 8 g is gradually added dropwise at a constant rate of 1.5 ml/min. At the time of dropping, fine particles in the liquid were initially deposited, but were fixed on the surface of the core powder, and the surface was covered with the deposited fine particles having a particle size of 0.01 to 0.5 micron.

(2) Washing and Drying After completion of the film-forming reaction, decantation was performed with pure water to remove unreacted components, excess sulfuric acid, and sulfuric acid formed by the reaction.
Solid-liquid separation was performed, and after drying with a vacuum dryer, dried powder was obtained.
The obtained dry powder is heated in a rotary tube furnace at 650° C. for 3 hours.
By performing overheat treatment (calcination) for 0 minutes, silica/titania-coated magnetite powder B ₂ was obtained. The color of the obtained B ₂ was light reddish purple. The surface of this B ₂ was slightly uneven, and a convex portion of titania fine particles was also partially seen.

(Third-layer silica film formation) (when the film surface is confined by a silica thin film) In the same manner as in Example 1, buffer solutions 1 and 2 and an aqueous sodium silicate solution (water glass solution) were prepared in advance. It was (1) Silica film formation Titania/silica-coated powder B _{2 (} 15 g) was added to 70 ml of a buffer solution prepared in advance, the dropping rate of the silica raw material solution was the same as in the case of the first layer coating, and the dropping amount was changed. A film was formed to 13 ml and reacted for 2 hours until there were no unreacted substances. After the film forming reaction is completed, the slurry containing the silica film forming powder is repeatedly decanted with sufficient water and washed. After washing, put the silica film powder in a vat, separate it by sedimentation, discard the upper liquid, and dry it in air in a dryer.
Dry at 50°C for 8 hours, and then in a nitrogen atmosphere at 500°C for 30 hours.
It was heat treated for minutes to obtain a silica-coated magnetite powder B ₃ . This three-layer film-coated powder B ₃ was light reddish purple, and its magnetization at 1 kOe was 30 emu/g. The film thickness of the silica coating film of the obtained silica/titania-coated magnetite powder B ₃ was 10 nm. The reflection peak of this three-layer film coating is 38
It was 0 nm and 773 nm. Table 3 shows each refractive index, the film thickness, the peak wavelength of the spectral reflection curve of the coated powder and the reflectance at the peak wavelength of the first to third layers. Table 2 shows the measured values of the final coated powder in the standard color system of L ^* , a ^* , and b ^*.
Shown in.

[0066]

[Table 3]

[Example 3] (Magenta powder particles were magenta-colored and coated with four layers of water) (First layer silica film formation) In the same manner as in Example 1, buffer solutions 1, 2, 3 and an aqueous solution of sodium silicate were prepared. (Water glass solution) was prepared. (1) Silica film 40 g of granular (octahedral) magnetite powder (average particle size 0.7 μm) was placed in a previously prepared mixed solution of buffer solution 1,460 ml and pure water 500 ml, and 2
Ultrasonic waves are applied in an ultrasonic bath of 8 kHz and 600 W, and further dispersed in a buffer solution containing magnetite powder with stirring. 400 ml of an aqueous sodium silicate solution (40 ml/
Min) and gradually decomposed by reaction to deposit a silica film on the surface. After the addition of the aqueous sodium silicate solution was completed, the reaction was continued for another 2 hours to react all unreacted raw materials. After the film forming reaction is completed, the slurry containing the silica film forming powder is repeatedly decanted with sufficient water and washed. After washing, the silica film-forming powder was placed in a vat, separated by sedimentation, and the upper liquid was discarded, followed by drying in a dryer at 150° C. for 8 hours to obtain silica-coated magnetite powder C ₁ .

(Formation of second layer titania film) Buffer solution 4 was prepared and prepared in the same manner as in Example 1. (1) Titanium Sulfate Aqueous Solution Water was added to titanium sulfate so that the concentration of TiO _{2 in} the aqueous solution was 60 g/liter, and the solution was prepared to give a titanium sulfate aqueous solution. (2) Titania film formation To 20 g of C ₁ obtained, prepare 750 ml of a buffer solution, and while ultrasonically dispersing C ₁ in the solution, sufficiently disperse in an ultrasonic dispersion tank, and then temperature of the liquid. While maintaining the temperature at 40°C to 50°C, 139 ml of an aqueous titanium sulfate solution prepared in advance was gradually added dropwise at 0.5 (ml/min). After the dropping, the reaction was continued for 3 hours to deposit the unreacted titania raw material. (2) Washing and drying By decanting with pure water to remove unreacted components, excess sulfuric acid and sulfuric acid formed by the reaction, solid-liquid separation is performed,
After drying with a vacuum dryer, a dry powder was obtained. The obtained dry powder was subjected to a heat treatment in a rotary tube furnace at 500° C. for 30 minutes to obtain silica-titania-coated magnetite powder C ₂ having a substantially smooth surface. This two-layer film-coated powder C ₂ had a magenta color, and its magnetization at 1 kOe was 33 emu/g.

(Formation of third layer silica film) Powder silica/
Add 15 g of titania-coated magnetite powder C ₂ to 365 ml of buffer solution prepared in advance, and add 28 kH
Ultrasonic waves are applied in a z, 600 W ultrasonic bath, and further dispersed in a buffer solution containing magnetite powder with stirring. 122 ml (40 ml/min) of an aqueous sodium silicate solution prepared in advance was added thereto, and the reaction was gradually decomposed to deposit a silica film on the surface. After the addition of the aqueous sodium silicate solution was completed, the reaction was continued for another 2 hours to react all unreacted raw materials. After completion of the film forming reaction, the slurry containing the silica/titania film forming powder is repeatedly decanted with sufficient water and washed. After washing
The silica film-forming powder was put in a vat, separated by settling, the upper liquid was discarded, and then dried in an air oven at 150° C. for 8 hours to obtain a silica/titania-coated magnetite powder C ₃ .

(Formation of fourth layer titania film) Same as in Example 1
Buffer solution 4 and 60 g/lit similar to the above second layer
Prepare an aqueous titanium sulfate solution and prepare it in advance
It was (1) Titania film formation Obtained C₃ , 110 g of buffer solution for 20 g
And prepare C in the solution. ₃ While ultrasonically dispersing the
After sufficiently dispersing in a dispersion tank, the temperature of the liquid is 40°C to 50°C.
Titanium sulfate prepared in advance while keeping
Gradually drop 145 ml of the aqueous solution at 0.5 (ml/min).
Defeated After dropping, the reaction was continued for 3 hours and unreacted titania
The raw material was deposited.

(Washing and Drying) By decanting with pure water, unreacted components, excess sulfuric acid, and sulfuric acid formed by the reaction were removed, solid-liquid separation was performed, and dried with a vacuum dryer to obtain a dry powder. The resulting dry powder was placed in a rotary tube furnace for 6
Superheat treatment was performed at 50° C. for 30 minutes to obtain silica/titania-coated magnetite powder C ₄ having a substantially smooth surface. The four-layer film-coated powder C ₄ had a magenta color, and its magnetization at 1 kOe was 19 emu/g. The thickness of the titania coating film of the obtained silica/titania-coated magnetite powder C ₄ was 41 nm. The reflection peak of this 4-layer film coating is 37
It was 7 nm and 771 nm. Table 4 shows the respective refractive indexes, the film thicknesses, the peak wavelengths of the spectral reflection curves of the coated powders and the reflectances at the peak wavelengths of the first to fourth layers. Table 2 shows the measured values of the final coated powder C _{4 in} the L ^* , a ^* , b ^* standard color system.

[0072]

[Table 4]

[Example 4] (Magnetization of magnetite powder particles, water-based coating with 5 layers) (First layer silica film formation) A buffer solution was prepared in the same manner as in Example 1. (1) Silica film 50 g of granular (octahedral) magnetite powder (average particle size: 0.7 micron) was placed in a previously prepared mixed solution of buffer solution 1, 460 ml and pure water 500 ml, and 2
Ultrasonic waves are applied in an ultrasonic bath of 8 kHz and 600 W, and further dispersed in a buffer solution containing magnetite powder with stirring. 400 ml of an aqueous sodium silicate solution (40 ml/
Min) and gradually decomposed by reaction to deposit a silica film on the surface. After the addition of the aqueous sodium silicate solution was completed, the reaction was continued for another 2 hours to react all unreacted raw materials. After the film forming reaction is completed, the slurry containing the silica film forming powder is repeatedly decanted with sufficient water and washed. After washing, the silica film-forming powder was put in a vat, separated by sedimentation, and the upper liquid was discarded, followed by drying in a dryer at 150° C. for 8 hours to obtain silica-coated magnetite powder D ₁ .

(Formation of second layer titania film) Buffer solution 4 similar to that in Example 1 and 60 g/liter titanium sulfate aqueous solution similar to Example 3 were prepared and prepared in advance. (1) Titania film formation A mixed solution of 750 ml of a buffer solution and 750 ml of pure water was prepared for 20 g of D ₁ obtained, and D ₁ was ultrasonically dispersed in the solution while being sufficiently dispersed in an ultrasonic dispersion tank. After the dispersion, the temperature of the liquid was maintained at 55°C to 60°C, and 120 ml of the titanium sulfate aqueous solution prepared in advance was added to 0.5 (m
(1/min) was gradually added dropwise. After the dropping, the reaction was continued for 3 hours to deposit the unreacted silica raw material on the surface of D ₁ . (2) Washing and drying By decanting with pure water to remove unreacted components, excess sulfuric acid and sulfuric acid formed by the reaction, solid-liquid separation is performed,
After drying with a vacuum dryer, a dry powder was obtained. The obtained dry powder was subjected to a heat treatment at 650° C. for 30 minutes in a rotary tube furnace to obtain silica/titania-coated magnetite powder D ₂ having a substantially smooth surface. This two-layer film coating was magenta and its magnetization at 1 kOe was 32 emu/g.

(Third Layer Silica Film Formation) 37 g of silica/titania-coated magnetite powder D ₂ was placed in a previously prepared mixed solution of buffer solution 1, 460 ml and pure water 500 ml, and ultrasonic waves of 28 kHz and 600 W were applied. Ultrasonic waves are applied in a bath and further dispersed in a buffer solution containing magnetite powder with stirring. 300ml of sodium silicate solution prepared in advance
(40 ml/min), and the reaction was gradually decomposed to deposit a silica film on the surface. After the addition of the aqueous sodium silicate solution was completed, the reaction was continued for another 2 hours to react all unreacted raw materials. After the film forming reaction is completed, the slurry containing the silica film forming powder is repeatedly decanted with sufficient water and washed. After washing, put silica/titania film-making powder in a vat,
After separating by sedimentation and discarding the upper liquid, 150
After drying at 8° C. for 8 hours, silica/titania-coated magnetite powder D ₃ was obtained.

(Formation of Fourth Layer Titania Film) Buffer solution 4 similar to that in Example 1 and 60 g/liter titanium sulfate aqueous solution similar to Example 3 were prepared and prepared in advance. (1) Titania film formation A mixed solution of 450 ml of a buffer solution and 750 ml of pure water was prepared with respect to 20 g of D ₃ obtained, and while D ₃ was ultrasonically dispersed in the solution, it was sufficiently dispersed in an ultrasonic dispersion tank. After the dispersion, the temperature of the liquid was maintained at 55°C to 60°C, and 124 ml of the titanium sulfate aqueous solution prepared in advance was added to 0.5 (m
(1/min) was gradually added dropwise. After the dropping, the reaction was continued for 3 hours to deposit an unreacted silica raw material on the surface of D ₃ . (4) Washing and drying By decanting with pure water to remove unreacted components, excess sulfuric acid and sulfuric acid formed by the reaction, solid-liquid separation is performed,
After drying with a vacuum dryer, a dry powder was obtained. The obtained dry powder was subjected to a heat treatment in a rotary tube furnace at 650° C. for 30 minutes to obtain a silica/titania-coated magnetite powder D ₄ having a substantially smooth surface.

(Fifth Layer Silica Film Formation) 37 g of silica/titania-coated magnetite powder D ₄ was added to a previously prepared mixed solution of 1,460 ml of buffer solution and 500 ml of pure water, and it was heated at 28 kHz and 600 W or more. Ultrasonic waves are applied in a sonic bath, and further dispersed in a buffer solution containing magnetite powder with stirring. 40m of sodium silicate solution prepared in advance
1 (40 ml/min), and the reaction was gradually decomposed to deposit a silica film on the surface. After the addition of the aqueous sodium silicate solution was completed, the reaction was continued for another 2 hours to react all unreacted raw materials. After the film forming reaction is completed, the slurry containing the silica film forming powder is repeatedly decanted with sufficient water,
Wash. After washing, the silica/titania film-forming powder was placed in a vat, precipitated and separated, and the upper liquid was discarded, followed by drying in a dryer at 150° C. for 8 hours to obtain silica/titania-coated magnetite powder D ₅ . .. The 5-layer film-coated powder D ₅ was light reddish purple, and its magnetization at 1 kOe was 21 emu/g. Obtained silica/titania-coated magnetite powder B
_The film thickness of the silica coating film of ₅ was 11 nm. The reflection peaks of this 5-layer film coating were 378 nm and 770 nm. Table 5 shows each refractive index of each of the first to fifth layers, the film thickness, the peak wavelength of the spectral reflection curve of the coated powder, and the reflectance at the peak wavelength. In addition, L ^* , a ^* , b ^{* of} the final coated powder
Table 2 shows the measured values in the standard color system.

[0078]

[Table 5]

[0079]

As described above, the magenta colored powder of the present invention can be formed into a film at a lower manufacturing cost than that of the alkoxide method by using water as a solvent in the film forming reaction in the manufacturing method. The effect that can be obtained is obtained. Further, at least one layer of the coating film on the surface of the base particles is a film composed of an aggregate of crystallized fine particles and crystallized fine particles having voids between the crystallized fine particles (hereinafter, simply referred to as a crystallized fine particle constituent film). By increasing the refractive index difference between the surface of the crystallized fine particles and the voids, scattering reflection of light is caused, the reflection effect is enhanced, and a functional powder of magenta color tone having excellent brightness is provided. It became possible to do.

The magenta color powder of the present invention obtained as described above is used as a magenta color composite raw material powder as a raw material for pigments, powder metallurgy, ceramic raw materials, electronic industry, etc. without using dyes or pigments. It is also possible to produce the same, and it is possible to maintain excellent performance in place of conventional pigments used in pigments for color inks and fillers for plastics and paper, and to provide a stable color tone even during long-term storage. In addition to having these excellent functions, when a magnetic substance, a conductor, or a dielectric substance is used as the substrate, it reacts with an external factor such as an electric field or a magnetic field to move, rotate,
It has a function of exerting an additional action such as movement and heat generation. For example, when a magnetic material is applied as a substrate, it can be applied as a pigment for color magnetic toner or color magnetic ink.
It is a great place to contribute to the industrial world.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an example of magenta colored powder of the present invention.

FIG. 2 is an enlarged cross-sectional view of a crystallized fine particle constituent film 2 included in the magenta colored powder of FIG.

[Explanation of symbols]

1 Base particle 2 Crystallized fine particle constituent film 3 Crystallized fine particle 4 Ultra fine particle

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Hoshino 1-8 Hirai, Hinode-cho, Nishitama-gun, Tokyo Inside Iron Mining Co., Ltd. No. 5 1403 F term (reference) 4J037 AA04 AA05 AA08 AA09 AA10 AA15 AA18 AA19 AA22 AA25 AA26 AA27 AA30 CA05 CA09 CA11 CA12 CA15 CA19 CA20 CA24 CA25 CC01 CC12 CC13 CC05 CC12 CC23 CC04 CC27 CC14 DD02 CC02 CC14 DD13 EE35 EE46 EE48 FF06 FF28 4K018 BA20 BC28 BD04

Claims (26)

[Claims] 1. A coating film is provided on the surface of a substrate particle, and at least one layer of the coating film is formed by a reaction of a metal salt in an aqueous solvent. Has a peak between 850 nm and 450
Magenta powder characterized by exhibiting a reflection spectrum having a bottom in the range of ˜650 nm. 2. The magenta colored powder according to claim 1, wherein the coating film formed by the reaction of the metal salt in an aqueous solvent satisfies the condition of the following formula. N
d=mλ/4 [In the formula, N=n+iκ (i represents a complex number) n: Refractive index of a substance constituting the film d: Film thickness m: Natural number λ: Peak wavelength of the reflection spectrum of the powder ( However, λ is 350 to 450 nm and 700 to 850.
nm) κ: attenuation coefficient] 3. The magenta colored powder according to claim 1, wherein the coating film on the surface of the base particles is a multilayer film. 4. The magenta powder according to claim 3, wherein each of the multilayer films is formed by a reaction of a metal salt in an aqueous solvent. 5. The magenta colored powder according to claim 3, wherein each of the multilayer films satisfies the condition of the following formula. Nd=mλ/4 [In the formula, N=n+iκ (i represents a complex number) n: Refractive index of a substance forming a film d: Film thickness m: Natural number λ: Peak wavelength of a reflection spectrum of powder ( However, λ is 350 to 450 nm and 700 to 850.
nm) κ: attenuation coefficient] 6. The magenta colored powder according to claim 1, wherein at least one layer of the coating film on the surface of the base particles is constituted as an aggregate of crystallized fine particles having voids. . 7. The coating film formed as an aggregate of crystallized fine particles having voids is capable of imparting lightness by scattering and reflection of light generated between the surface of the crystallized fine particles and voids. The magenta colored powder according to claim 6, wherein 8. A dense coating film composed of ultrafine particles capable of closing the voids on the surface is provided on the surface of the coating film formed as an aggregate of crystallized fine particles having voids. The magenta colored powder according to claim 6, which is characterized in that. 9. The magenta color powder according to claim 6, wherein the coating film formed as an aggregate of crystallized fine particles having voids is a high refractive index film. 10. The magenta colored powder according to claim 8, wherein the dense film is a silica film. 11. The coating film formed as an aggregate of crystallized fine particles having voids forms solid phase fine particles in a reaction solution for forming the coating film, and the solid phase fine particles are formed into The magenta colored powder according to claim 6, which is formed by firing after being incorporated into the coating film. 12. The magenta colored powder according to claim 11, wherein the reaction solution is an aqueous solution. 13. Before the firing, the coating film in which the solid phase fine particles are incorporated is coated with ultrafine particles capable of forming a dense film that closes voids on the surface of the coating film. The magenta colored powder according to claim 11, characterized in that 14. A method for producing a magenta powder by forming a coating film on the surface of base particles, wherein the powder obtained has peaks between 350 and 450 nm and between 700 and 850 nm, and A method for producing magenta colored powder, characterized in that at least one layer of the coating film is formed by a reaction of a metal salt in an aqueous solvent so as to exhibit a reflection spectrum having a bottom between 450 and 650 nm. . 15. The method for producing magenta colored powder according to claim 14, wherein the coating film formed by the reaction of a metal salt in an aqueous solvent is formed so as to satisfy the condition of the following formula. .. Nd=mλ/4 [In the formula, N=n+iκ (i represents a complex number) n: Refractive index of a substance forming a film d: Film thickness m: Natural number λ: Peak wavelength of a reflection spectrum of powder ( However, λ is 350 to 450 nm and 700 to 850.
nm) κ: attenuation coefficient] 16. The method for producing magenta colored powder according to claim 14, wherein the coating film formed on the surface of the base particles is a multilayer film. 17. The method for producing magenta colored powder according to claim 16, wherein each of the multilayer films is formed by a reaction of a metal salt in an aqueous solvent. 18. The multilayer film is formed so as to satisfy all the conditions of the following formula.
A method for producing the magenta powder as described. Nd=mλ/4 [In the formula, N=n+iκ (i represents a complex number) n: Refractive index of a substance forming a film d: Film thickness m: Natural number λ: Peak wavelength of a reflection spectrum of powder ( However, λ is 350 to 450 nm and 700 to 850.
nm) κ: attenuation coefficient] 19. The method for producing magenta colored powder according to claim 14, wherein at least one layer of the coating film formed on the surface of the base particles is constituted as an aggregate of crystallized fine particles having voids. . 20. The coating film, which is formed as an aggregate of crystallized fine particles having voids, is formed so that lightness can be imparted by scattering and reflection of light generated between the surface of the crystallized fine particles and the voids. The method for producing magenta colored powder according to claim 19, which is characterized in that. 21. A dense film is formed on the surface of the coating film formed as an aggregate of crystallized fine particles having voids, with ultrafine particles capable of closing the voids on the surface. 19. The method for producing magenta colored powder according to item 19. 22. The method for producing magenta colored powder according to claim 19, wherein the coating film formed as an aggregate of crystallized fine particles having voids is a high refractive index film. 23. The method for producing magenta colored powder according to claim 21, wherein the dense film is a silica film. 24. The coating film, which is formed as an aggregate of crystallized fine particles having voids, is formed into solid phase fine particles in a reaction solution for forming the coating film, and the solid phase fine particles are coated with the solid phase fine particles. 20. The method for producing magenta colored powder according to claim 19, which is formed by firing after being incorporated into the covering film. 25. The method for producing magenta colored powder according to claim 24, wherein the reaction solution is an aqueous solution. 26. Before the firing, the coating film in which the solid phase fine particles are incorporated is coated with ultrafine particles capable of forming a dense film that closes voids on the surface of the coating film. 25. The method for producing magenta colored powder according to claim 24, wherein