JP2003321623A - Method for producing inorganic pigment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an inorganic pigment not containing noxious chromium or the like, and having similar sizes and a high chroma. <P>SOLUTION: (A) An inorganic powder obtained by covering the surface of a substrate particle with a coloring inorganic compound, and (B) an inorganic salt are mixed and heat-treated at a temperature not lower than the melting point and not higher than the boiling point of the inorganic salt. The ratio of the components (B)/(A) is ≥0.5. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a highly colored inorganic pigment having a uniform size and containing no harmful chromium or the like. [0002] Inorganic pigments are chemically stable compared to organic pigments, and have excellent heat resistance and weather resistance. Therefore, inorganic pigments are widely used in cosmetics, paper, paints, printing, plastics, porcelain and the like. Used. [0003] However, inorganic pigments have a problem that they are inferior to organic pigments in vividness.
Harmful chromium and lead are often used. Therefore, there is a demand for an inorganic pigment having a beautiful color with high saturation without using harmful chromium or lead in the environment. Heretofore, in the production of inorganic pigments, in the case of mixing and producing appropriate raw material powders, generally, the raw material powders are formed by various methods, then sintered and pulverized. In such a production method, in order to color the whole including the inside of the particles, it is not possible to obtain a sufficiently colored and highly saturated inorganic pigment unless a large amount of relatively expensive raw materials necessary for coloring are used. . Furthermore, since the inorganic pigment is obtained by pulverizing the sintered body, there is a problem that the shape of the inorganic pigment is not constant and the distribution of the particle diameter is wide. [0005] One method for solving the above problem is to use a relatively inexpensive raw material as base particles and coat the base particles with a relatively expensive raw material required for coloring. is there. For example, in JP-A-7-331110, Co, Ni, Mn, which reacts with alumina to produce a colored spinel oxide on plate-like alumina obtained by hydrothermal synthesis,
A method for producing a plate-like alumina pigment by coating a compound containing an element such as Fe and calcining the same is disclosed. However, since the coated compound is reactive, the particles are strongly bonded during calcination,
There is a risk of aggregation. Further, when the strongly bonded particles are pulverized, the colored spinel oxide generated on the surface of the particles may be lost, and it is difficult to obtain a highly-saturated inorganic pigment having a uniform size. . Means for Solving the Problems The present invention has been intensively studied in order to solve the above-mentioned problems, and as a result, a specific amount of the inorganic powder in which the surface of the base particles is coated with the colored inorganic compound is determined. By adding and mixing the inorganic salt of the above, by subjecting the mixture to a specific heat treatment, it does not contain harmful chromium or the like, and has a uniform size.
The inventors succeeded in obtaining an inorganic pigment having high chroma and completed the present invention. That is, the present invention has the following features. 1. A method for producing an inorganic pigment obtained by mixing (A) an inorganic powder in which the surface of a base particle is coated with a colored inorganic compound and (B) an inorganic salt, and subjecting the mixture to a heat treatment, wherein the heat treatment temperature is the inorganic salt. (B)
/ (A) is 0.5 or more, a method for producing an inorganic pigment. Hereinafter, the present invention will be described in detail based on its embodiments. The method for producing an inorganic pigment according to the present invention comprises:
(A) An inorganic powder (hereinafter also referred to as “component (A)”) in which the surface of a base particle is coated with a colored inorganic compound, and (B) an inorganic salt (hereinafter also referred to as “component (B)”) are mixed. And heat treating the mixture. The colored inorganic compound used for coating the base particles generates a stable colored compound that develops a beautiful color by heat treatment, and finally develops the color of the inorganic pigment. In the present invention, the heat treatment temperature is from the melting point of the inorganic salt to the boiling point, and (B) / (A) is 0.5 by weight.
Or more (preferably 1 or more, more preferably 3 or more 15
Below) is mandatory. By setting to such conditions, in the heat treatment, the inorganic salt is in a liquid state, is easily filled in the voids between the particles, and heat is transmitted uniformly and stably to the entire system, so that the uniformity of color development is maintained. An extremely high and stable inorganic pigment can be obtained in a short time. Further, the particles are hardly in contact with each other, and the bonding between the particles can be suppressed. Further, after the heat treatment, the inorganic pigment can be easily separated only by washing the inorganic salt, and a colored compound having a uniform size and high saturation can be obtained without loss of the colored compound. (Substrate particles) The substrate particles in the present invention are:
For example, Fe, V, Ni, Al, Zn, Ti, Si, Z
Inorganic compounds containing r, Ga or the like as a main component are exemplified. As the base particles, for example, metals such as titanium, zinc, aluminum and zirconium, calcium oxide, iron oxide,
Vanadium oxide, nickel oxide, aluminum oxide, zinc oxide, titanium oxide, silicon oxide, magnesium oxide,
Oxides such as zirconium oxide and indium oxide, sulfides such as zinc sulfide, copper sulfide, and iron sulfide, barium sulfate, titanium sulfate, zinc sulfate, aluminum sulfate, magnesium sulfate, and other sulfates, calcium phosphate, titanium phosphate, and zinc phosphate , Such as phosphates such as silicon phosphate, aluminum phosphate, magnesium phosphate, zirconium phosphate, calcium silicate, titanium silicate, zinc silicate, silicon silicate, aluminum silicate, magnesium silicate, zirconium silicate, etc. Hydroxides such as iron and the like may be mentioned, and a composite of two or more of these may be used. In addition, commercially available products can also be used. In the present invention, in particular, zinc oxide, titanium oxide, and the like are preferably used as inexpensive base particles. The particle size of the base particles is not particularly limited, but is preferably 0.01 to 100 μm (preferably 0.1 to 10 μm). The shape of the base particles is not particularly limited, and may be spherical, needle-like, plate-like, rod-like, fibrous, tree-like, sea-star-like, or the like. (Colored Inorganic Compound) The colored inorganic compound in the present invention is a compound that obtains a stable colored compound that develops a beautiful color by heat treatment, and finally develops the color of the inorganic pigment. The colored inorganic compound is used after being coated on the surface of the base particles. Examples of a method for coating the colored inorganic compound include a precipitation method and the like. The precipitation method is a method in which a compound containing a metal ion is gradually formed on the surface of the base particles in a solution in which the base particles are mixed. In this case, the amount of the element contained in the coating can be changed in a wide range. Examples of such a colored inorganic compound include Mn, Fe, Co, Ni, Cu, Zn, V, Y, and T.
Compounds containing a metal element such as i, Sn, Sb, Mg, Ca, Bi and the like can be mentioned. By appropriately selecting these metal elements, various colors can be developed. As the coloring inorganic compound, for example, chlorides, bromides, acetylacetonates, acetates containing the above metal elements,
Examples thereof include borates, carbonates, sulfates, oxalates, nitrates, and the like, and mixtures thereof. In the present invention, the colored inorganic compound coated on the surface of the base particles can be heat-treated to form a stable colored compound and exhibit a beautiful color. Such a colored inorganic compound can react alone by heat treatment to produce a colored compound,
A colored compound can also be produced by the reaction between the base particles and the colored inorganic compound. In particular, an inorganic pigment having more excellent heat resistance and weather resistance can be obtained by appropriately setting a substance in which the base particles and the colored inorganic compound react by heat treatment. The base particles and the colored compound are not particularly limited as long as they are the compounds described above. Examples of the crystal structure include a rutile crystal structure, an anatase crystal structure, a wurtzite crystal structure, a wurtz crystal structure, a zinc blende crystal structure, a spinel crystal structure, an inverse spinel crystal structure, and a corundum crystal structure. , A priderite type crystal structure, a NaCl type crystal structure, and the like. The crystal structures of the base particles and the colored compound may be the same or different, but those having the same crystal structure are preferred. With the same crystal structure, an inorganic pigment having more excellent heat resistance and weather resistance can be obtained. (Inorganic Salt) The inorganic salt of the present invention is not particularly limited as long as it does not burn during heat treatment and is chemically stable, but its melting point is from 500 ° C. to 1600 ° C. (preferably from 800 ° C. to 1300 ° C.). C). As the inorganic salt, for example, a water-soluble metal halide, phosphate, silicate, sulfate, or the like can be used. For example, sodium fluoride, potassium fluoride, magnesium fluoride, calcium fluoride, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium bromide, potassium bromide, magnesium bromide, calcium bromide, sodium phosphate, Potassium phosphate, magnesium phosphate, calcium phosphate, sodium silicate, potassium silicate, magnesium silicate, calcium silicate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and the like can be used.
Particularly, sodium chloride, potassium chloride, magnesium chloride and calcium chloride are preferred. (Method for Producing Inorganic Pigment) In the method for producing an inorganic pigment of the present invention, the ratio (B) / (A) of component (A) and component (B) is 0.5 or more (preferably 1 or more) by weight ratio. And more preferably 3 to 15), and heat-treating the mixture at a temperature from the melting point to the boiling point of the component (B). In mixing the components (A) and (B),
Component (B) can be added to the dry powder of component (A) or to a presscake or suspension from the synthesis process. The component (B) may be dissolved in water and / or an organic solvent before addition, or may be added to the component (A) in a solid form. If necessary, the mixture containing the components (A) and (B) can be dispersed by a conventional method using a mechanical dispersion medium such as a ball mill. The stirring time may be usually set in the range of 20 minutes to 12 hours. The mixing ratio of the components (A) and (B) is such that the weight ratio (B) / (A) is 0.5 or more, preferably 1 or more, and more preferably 3 or more and 15 or less. If it is less than 0.5, the particles may come into contact with each other and bond, and the variation in the particle size increases, and the uniformity of color development is lost. Further, the heat treatment may take time. The heat treatment temperature is set at a temperature not lower than the melting point of the inorganic salt and not higher than the boiling point. In such a temperature range, the inorganic salt is in a liquid state, and heat is uniformly and stably transmitted to the entire system, so that uniformity of color development is maintained, and a stable inorganic pigment with high chroma can be obtained in a short time. Can be. Heat treatment temperature is usually 500 ° C
To 1600 ° C (preferably 800 to 1300 ° C)
Is preferable, and in such a temperature range,
The colored inorganic compound can produce a stable colored compound that expresses a beautiful color, and an inorganic pigment with higher saturation can be obtained. If the heat treatment temperature is lower than the melting point, the inorganic salt does not melt and the heat is not transmitted uniformly, so that the pigment may be uneven in color. In addition, the reaction of the coated colored inorganic compound may not proceed sufficiently, and a vivid color may not be obtained. The present invention is also characterized in that heat treatment can be performed in a short time. The heat treatment time is preferably from 10 minutes to 3 hours (preferably from 15 minutes to 2 hours). The heat treatment can be performed in the air, in a reducing atmosphere, or in an oxidizing atmosphere. Further, after the heat treatment, the inorganic pigment can be easily separated by washing the component (B), and a colored compound having a uniform size and high saturation can be obtained without losing the colored compound. it can.
The component (B) can be easily washed and removed using water and / or an organic solvent (preferably water) or the like, and can be used repeatedly by drying the washing liquid. (Inorganic Pigment) The average particle size of the inorganic pigment thus obtained can be appropriately controlled depending on the base particles used, the colored inorganic compound and the like.
It is preferably 00 μm (preferably 0.1 to 10 μm). In such a range, the coloring power and hiding power of the pigment are large, and the pigment tends to be easily dispersed. According to the production method of the present invention, pigments having a uniform size and a small variation in particle diameter can be obtained. The variation in particle size is 70% or less (preferably 60% or less, more preferably 5% or less).
0% or less). When the variation in the particle diameter is 70% or less, the inorganic pigment is uniform in size and has high saturation. In addition, the shape of the inorganic pigment can be manufactured into various shapes depending on the shape of the base particles, the amount of the colored inorganic compound to be coated, and the like. For example, a spherical shape, a needle shape, a plate shape, a rod shape,
It is possible to produce fibrous, dendritic, sea-star, etc. The variation in particle diameter is defined as: variation in particle diameter (%) = (standard deviation / average particle diameter) ×
It is indicated by 100 (%), and the smaller the value, the better the dispersibility. The average particle size is the average particle size of the pigment that can be observed with a scanning electron micrograph. The inorganic pigment of the present invention can be used for cosmetics, paints, paper, ink, printing, plastics, ceramics and the like. For example, when used for paints, resin compositions, and ceramics, paints, resin compositions, and ceramics having inexpensive and beautiful colors can be manufactured. EXAMPLES Examples will be shown below to further clarify the features of the present invention, but the present invention is not limited to these examples. (Measurement method) The crystal structure was determined using an X-ray diffractometer (RINT-1100,
(Manufactured by Rigaku Corporation). 2. The particle size was observed with an electron microscope (JSM-5310, manufactured by JEOL Ltd.). (Example 1) Pigments were prepared by the following method using "fine zinc oxide type 2 fine particles" (trade name) (average particle size 0.25 µm) manufactured by Mitsui Kinzoku Co., Ltd. as base particles. . 1. 100 g of two kinds of zinc oxide fine particles are mixed with 1 liter of water,
8.5 g of CoCl ₂ .6H ₂ O were added. A precipitation treatment was performed by dropping a 2.1 mol / l aqueous solution of Na ₂ CO ₃ . 3. After being filtered and washed, it was dried at 110 ° C. to obtain a zinc oxide powder coated with basic cobalt carbonate. 4. Zinc oxide powder 10 coated with basic cobalt carbonate
0 g and 800 g of NaCl ((B) / (A) = 8)
The mixed powder was heat-treated at 1000 ° C. for 30 minutes. The melting point of NaCl is about 800 ° C. and the boiling point is about 1413 ° C. 5. After cooling, the mixed powder was washed with water to remove NaCl and dried. Through the above operations, pigment powders having a uniform size with an average particle size of 0.5 μm and a particle size variation of 34% were obtained. When the obtained pigment powder was visually confirmed, it exhibited a highly saturated green color. FIG. 1 shows the X-ray diffraction patterns of the zinc oxide used as the base particles and the pigment obtained by the above operation. In X-ray diffraction of pigment powder,
No diffraction pattern other than the wurtz phase was observed. This X-ray diffraction pattern showed that an oxide having a wurtzite crystal structure similar to zinc oxide was also formed on the surface of the base particles. FIG. 2 shows an electron micrograph of the obtained powder. Example 2 A pigment powder was prepared in the same manner as in Example 1 except that the amount of CoCl ₂ .6H ₂ O was changed to 10 g. The average particle size was 0.3 μm, and the particle size variation was 28%. %, And a green pigment powder having good saturation and uniform size was obtained. Further, the X-ray diffraction pattern of the obtained pigment was the same as in Example 1, and it was found that the pigment had a wurtz-type crystal structure. (Example 3) The base particles were manufactured by Mitsui Kinzoku Co., Ltd., "Two kinds of zinc oxide general products" (trade name) (average particle diameter of 2-3).
A pigment powder was prepared in the same manner as in Example 1 except that the average particle diameter was 5 μm, and the variation in the particle diameter was 3 μm.
A highly saturated green pigment powder having a size of 5% was obtained. The X-ray diffraction pattern of the obtained pigment is
As in Example 1, it was found that the crystal had a wurtz-type crystal structure. [0031] (Example 4) CoCl ₂ · 6H ₂ O instead of, except for using MnSO ₄ · 5H ₂ O, Example 1
When a pigment powder was prepared in the same manner as described above, the average particle diameter was set to 0.
A bright pink pigment powder having a uniform size of 5 μm and a particle diameter variation of 31% was obtained. The X-ray diffraction pattern of the obtained pigment was the same as that in Example 1,
It was found that it had a wurtz-type crystal structure. [0032] (Example 5) CoCl ₂ · 6H ₂ O instead of, except for using CuSO ₄ · 5H ₂ O, Example 1
When a pigment powder was prepared in the same manner as described above, the average particle diameter was set to 0.
A green pigment powder of 5 μm in size and good in color saturation having a particle size variation of 36% was obtained. The X-ray diffraction pattern of the obtained pigment was the same as that in Example 1,
It was found that it had a wurtz-type crystal structure. (Embodiment 6) Instead of NaCl, CaC
except for using l ₂ is was prepared in the same manner as pigment powder as in Example 1, the average particle diameter 0.6 .mu.m, a good green color saturation with a uniform size to 42% variation in the particle diameter A pigment powder was obtained. The melting point of CaCl ₂ is about 774.
° C, boiling point is about 1600 ° C or more. Further, the X-ray diffraction pattern of the obtained pigment was the same as in Example 1, and it was found that the pigment had a wurtz-type crystal structure. Example 7 A pigment powder was prepared in the same manner as in Example 1 except that the amount of NaCl was changed to 100 g. The average particle diameter was 0.8 μm, and the dispersion of the particle diameter was 52%.
A green pigment powder having good chroma was obtained. Also,
The X-ray diffraction pattern of the obtained pigment was the same as in Example 1, and it was found that the pigment had a wurtz-type crystal structure. Example 8 A pigment powder was prepared in the same manner as in Example 1 except that the amount of NaCl was changed to 200 g. The average particle diameter was 0.8 μm, and the dispersion of the particle diameter was 46%.
A green pigment powder having good chroma was obtained. Also,
The X-ray diffraction pattern of the obtained pigment was the same as in Example 1, and it was found that the pigment had a wurtz-type crystal structure. Example 9 A pigment powder was prepared in the same manner as in Example 1 except that the amount of NaCl was changed to 400 g. The average particle size was 0.7 μm, and the variation in the particle size was 42%.
A green pigment powder having good chroma was obtained. Also,
The X-ray diffraction pattern of the obtained pigment was the same as in Example 1, and it was found that the pigment had a wurtz-type crystal structure. Example 10 A pigment powder was prepared in the same manner as in Example 1 except that the amount of NaCl was changed to 600 g. The average particle diameter was 0.7 μm, and the dispersion of the particle diameter was 38%.
Thus, a green pigment powder having good size and good chroma was obtained. Further, the X-ray diffraction pattern of the obtained pigment was the same as in Example 1, and it was found that the pigment had a wurtz-type crystal structure. Example 11 1500 g of NaCl
A pigment powder was prepared in the same manner as in Example 1 except that the average particle size was 0.5 μm, and the particle size variation was 32.
%, And a green pigment powder having good saturation and uniform size was obtained. The X-ray diffraction pattern of the obtained pigment is
As in Example 1, it was found that the crystal had a wurtz-type crystal structure. Example 12 A pigment powder was prepared in the same manner as in Example 1 except that the amount of NaCl was changed to 60 g. The average particle diameter was 0.8 μm, and the dispersion of the particle diameter was 62%.
A green pigment powder having good chroma was obtained. Also,
The X-ray diffraction pattern of the obtained pigment was the same as that of Example 1, and it was found that the pigment had a wurtz crystal structure. Comparative Example 1 A pigment powder was prepared in the same manner as in Example 1 except that the amount of NaCl was changed to 40 g.
Many particles having an average particle size of 0.8 μm aggregated. Comparative Example 2 A pigment powder was prepared in the same manner as in Example 1 except that the heat treatment temperature was changed to 300 ° C.
Since Cl was not melted and heat was not transmitted uniformly, a pigment powder having uneven color was obtained. Furthermore, the reaction between the coated basic cobalt carbonate and zinc oxide did not sufficiently proceed, and a vivid color could not be obtained. According to the present invention, a specific amount of an inorganic salt is added to and mixed with an inorganic powder in which a colored inorganic compound is coated on the surface of a base particle, and the mixture is subjected to a specific heat treatment to remove harmful chromium and the like. And an inorganic pigment having a uniform size and high saturation can be obtained. [0043]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a powder X-ray diffraction pattern of the pigment produced in Example 1. FIG. 2 is an electron micrograph of the pigment produced in Example 1.

Claims (1)

Claims: 1. An inorganic pigment obtained by mixing (A) an inorganic powder in which the surface of a base particle is coated with a colored inorganic compound and (B) an inorganic salt and subjecting the mixture to heat treatment. A method for producing an inorganic pigment, wherein the heat treatment temperature is from the melting point to the boiling point of the inorganic salt and the weight ratio (B) / (A) is 0.5 or more.