JPH0781918A - Fine particle-shaped blue composite oxide pigment and production thereof - Google Patents

Abstract

PURPOSE:To produce a fine particle-shaped blue multiple oxide pigment contg. Co, Zn and Si and having satisfactory heat resistance. CONSTITUTION:This fine particle-shaped blue composite oxide pigment is made of Co-Zn-Si oxide in which the molar ratio of Co:Zn:Si is (0.05-1.5):(0.1-2.0):1 and has 5-20m<2>/g BET specific surface area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine particle composite oxide blue pigment and a method for producing the same, and more specifically, it is a fine particle composite composed of Zn, Co and Si oxides which are excellent in red clarity, transparency and heat resistance. It is intended to provide an oxide blue pigment.

[0002]

2. Description of the Related Art Conventionally, blue-based inorganic pigments have been dark blue,
Ultramarine and cobalt blue are widely used. Since the heat resistance, alkali resistance, and durability of the pigment itself are insufficient, it is difficult to use dark blue for coloring synthetic resins and paints. Ultramarine has poor acid resistance and its use may be limited. Further, since cobalt blue is excellent in various pigment characteristics, it can be used for most purposes unless economic considerations such as coloring density and price are taken into consideration. However, compared to ultramarine, the hue is more greenish, and reddish ones are required for some purposes.

As one of the blue-based inorganic pigments that meet this demand, there is a composite oxide pigment composed of oxides of cobalt, zinc and silicon. This pigment has a phenasite structure, a reddish hue, and is excellent in various fastnesses. However, pigments that are usually available on the market have a coarse particle size, and their use is limited to ceramics such as enamel. In addition, in applications such as synthetic resins and paints, not only is strong pulverization necessary to make fine particles, but also strong energy is applied to the particles, which adversely affects the physical properties of the final pigment. Exert.

[0004]

Problems to be Solved by the Invention Cobalt, zinc and silicon composite oxide blue pigments are usually manufactured by a dry method. That is, a method of uniformly mixing cobalt or zinc oxide or carbonate and silica, sometimes using a mineralizer together, firing at high temperature, and then pulverizing the sintered particles with a powerful pulverizer to form a pigment. However, unless each component is fine particles, it is difficult for the product after firing to become fine particles, and in order to make such fine particles, a large amount of energy must be added to the pigment.

As a result, it has been confirmed that the heat resistance of the obtained pigment is deteriorated. That is, when the pigment thus obtained is reheated to 200 ° C. to 250 ° C. or higher, the blue color disappears and the color tone becomes dull. The degree of discoloration or dullness depends on the heat resistance test temperature, time, atmosphere, crushing history of the pigment, and the like, but is a unique phenomenon not usually found in pigments obtained by firing at high temperature. Therefore, an object of the present invention is to provide a composite oxide pigment which does not have the above-mentioned drawbacks, that is, has good heat resistance, and which is composed of fine particles of cobalt, zinc and silicon.

[0006]

The above object can be achieved by the present invention described below. That is, the present invention is a constituent component,
The molar ratio of zinc, cobalt and silicon is in the range of 0.05 to 1.5 for cobalt and 0.1 to 2.0 for zinc with respect to silicon, and the BET specific surface area is 5 m ² / g to 20 m.
^A fine particle composite oxide blue pigment comprising oxides of cobalt, zinc and silicon, which is adjusted to ² / g, and a method for producing the same.

[0007]

According to the present invention, as a result of intensive studies to eliminate the drawbacks of the prior art, it was confirmed that the desired fine particle composite oxide blue pigment can be obtained by firing the precursor of the pigment obtained by the wet precipitation reaction. did. That is, an alkaline aqueous solution containing an alkali silicate as a precipitant is used in a mixed aqueous solution of cobalt salt and zinc salt, and each salt and silicic acid are added to an appropriate p
After coprecipitation with H, filtration, washing with water, drying, and 850 ° C to 95
It was confirmed that by firing at 0 ° C., a fine particulate fine particle composite oxide blue pigment having desired heat resistance was obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. As the cobalt and zinc salts used in the present invention, general salts such as sulfates, nitrates, chlorides and acetates of each metal can be used.
In the case of silicon, alkali silicates such as sodium orthosilicate, sodium metasilicate, and No. 3 sodium silicate can be used. As the alkali as the precipitant, general ones such as caustic soda and soda ash can be used.

In the above, the composition ratio of each component is such that the molar ratio of metal is such that cobalt is 0.05 to 1.
5, preferably 0.9-1.1 and zinc 0.1-2.
0, preferably 0.95 to 1.1, with zinc: cobalt: silicon = 1: 1: 1 being the most preferable, and the reddish and transparent blue coloration being the best in the above ratio. Is. Further, according to the results of the research conducted by the present inventor, it was confirmed that the color tone and the transparency were not significantly affected unless the molar ratio was significantly deviated from the above range. On the other hand, if the proportion of zinc is too large, the pigment obtained is poor in color development and the coloring power is lowered.

The metal salt of each constituent element as described above is dissolved in water to form a mixed salt aqueous solution. The concentration at that time is appropriately about 5 to 50% by weight as a whole in the above molar ratio. This mixed solution can be simultaneously dropped into a preliminarily prepared precipitation medium by using an alkaline aqueous solution such as caustic soda containing sodium silicate as a precipitant.
The reaction concentration at this time does not particularly affect the size, color tone and transparency of the particles, but considering workability and the like, it is preferably 0.05 mol / liter to 0.2 mol / liter. Is suitable, and the tendency is that the thinner the concentration, the smaller the particles and the better the transparency of the pigment.

The synthesis temperature is usually in the range of 0 ° C.
If the temperature is in the range of 100 ° C, the effect can be sufficiently exhibited. However, if the temperature is 60 ° C. or higher, the growth of particles, particularly the growth of silicic acid particles, is large, and the reactivity tends to decrease, resulting in poor color development. On the contrary, the particles tend to become small at low temperatures, and when the slurry concentration is low, gelation occurs and the pigment aptitude is lost. Therefore, 20 ° C to 50 ° C is desirable.
Further, the pH at the time of synthesis at this time is preferably 7 or more and 10 or less. When the pH is less than 7, cobalt and zinc metals do not precipitate, and when the pH exceeds 10, the particles of silicic acid tend to be large, and the particle size cannot be balanced with the hydroxides of other metal salts, resulting in color development. Is bad. In this way, a precipitate is formed while stirring for 30 minutes to 1 hour, and then aged for about 1 hour to complete the precipitation reaction.

Next, the obtained product is washed with water, filtered, and
By drying the obtained dried product at a temperature of about 00 ° C to 120 ° C and heat-treating the obtained dried product at a temperature of 850 ° C to 950 ° C for 30 minutes to 1 hour, the cobalt of the present invention,
A fine particulate composite oxide blue pigment composed of zinc and silicon can be obtained. The fine particulate composite oxide pigment of the present invention thus obtained, which is composed of cobalt, zinc and silicon, has a transparent and deep color tone as compared with the same kind of pigment obtained by the conventional dry method, and has a high heat resistance. It is a pigment with good properties, high coloring power and excellent redness. Further, by adjusting the BET specific surface area of the obtained fine particle pigment to 5 to ²⁰ m ² / g, the particle size is adjusted and the dispersion in the paint, resin and the like becomes good.

[0013]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, unless otherwise specified, "parts" and "%" in the text are based on weight. Example 1 107.1 parts of cobalt chloride hexahydrate and 129.4 parts of zinc sulfate heptahydrate are weighed, and water is added to completely dissolve them to make a total amount of about 1,000 parts. Next, 62 parts of caustic soda and 93.1 parts of sodium silicate No. 3 (silica content 29%) were weighed out as a precipitate and a silica source, and water was added to about 1 part.
000 copies.

About 7 water, which is a precipitation medium prepared in advance
Adjust 50 parts to about 45 ℃ with a gas burner or electric heater,
An aqueous mixed salt solution and an aqueous caustic soda solution containing sodium silicate are simultaneously added dropwise thereto, and the precipitation reaction is completed in about 30 minutes to 1 hour. The pH at this time is 7.5-8.
After paying attention to the 5th place, after dropping the mixed salt aqueous solution, excess caustic soda aqueous solution is continuously added to adjust the pH to about 9.0, followed by aging for about 60 minutes. Next, the product is taken out, thoroughly washed with water by decantation to wash away residual salt, and filtered. Then, it is dried at a temperature of 100 ° C. to 120 ° C. for 12 hours or more. This dried product is 900 ℃
After firing for 1 hour in an oxidizing atmosphere, it was cooled. The pigment thus obtained has fine particles and a BET specific surface area of 8.5.
It was m ² / g, was reddish blue and had high tinting strength.

Example 2 A pigment was obtained in the same manner as in Example 1 except that 133.8 parts of zinc nitrate hexahydrate was used instead of 129.4 parts of zinc sulfate heptahydrate. The pigment thus obtained has fine particles and
T specific surface area is 16.5 m ² / g, reddish blue color,
It was deep.

Comparative Example 1 84.27 parts of basic cobalt carbonate, zinc oxide (zinc white 1
No.) 66.39 parts and siloid 244 as silica content
(Fuji Davison) Weigh out 48.99 parts and water 1,0
Add 00 parts and 3 mmφ zirconia beads and mix thoroughly with a 2 liter ball mill. After filtering 1,10
After firing at 0 ° C. for 1 hour, it was sufficiently pulverized by a wet ball mill method to obtain a sample for comparison. The pigment thus obtained had a specific surface area of 11.0 m ² / g and was close in hue to those of Examples 1 and 2. The pigments obtained in Examples 1 and 2 and Comparative Example 1 were subjected to a heat resistance test in air at 300 ° C. for 1 hour, the color change before and after the test was measured, and evaluated by ΔE. The results are shown in Table 1 below. It was shown to.

[0017]

[Table 1] Heat resistance test results * In the heat resistance test, after dispersing with melamine alkyd resin (PHR30) on a paint shaker, the color was measured by spreading it on art paper with a 6 mil applicator.

[0018]

[Effect] As described above, according to the present invention, it is deeper, redder, has excellent transparency and sharpness, and has a high coloring power,
A fine particulate composite oxide blue pigment composed of cobalt, zinc and silicon having excellent heat resistance can be obtained, and the pigment can be used as a colorant for general paints and synthetic resins and a colorant for ceramics like conventional pigments. At the same time, it is expected to be applied to, for example, transparent paints, transparent thin films, printing inks, cosmetics, phosphors, abrasives, etc. by utilizing the characteristics.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, friend Mizukami, 1060 Narita, Odawara, Kanagawa Kasei Optonix Co., Ltd.

Claims (6)

[Claims] 1. The molar ratio of zinc, cobalt, and silicon, which are the constituents, is 0.05 to cobalt per 1 silicon.
1.5 and zinc in the range of 0.1 to 2.0, and B
An ET specific surface area is adjusted to 5 m ² / g to ²⁰ m ² / g, and a fine particle composite oxide blue pigment composed of oxides of cobalt, zinc and silicon. 2. The molar ratio of zinc, cobalt and silicon, which are the constituents, is 0.9-1.
The fine particle composite oxide blue pigment comprising the oxide of cobalt, zinc and silicon according to claim 1, wherein 1 and zinc are in the range of 0.95 to 1.1. 3. An ultrafine particle pigment produced by adding an alkaline aqueous solution containing an alkali silicate as a precipitant to a binary mixed solution of zinc salt and cobalt salt to form a coprecipitate, washing with water, filtering and drying. after preparing the precursor by calcination, cobalt BET specific surface area and adjusting the 5m ² / g~20m ² / g, fine particle composite oxide blue pigment consisting of oxides of zinc and silicon Manufacturing method. 4. The coprecipitation is performed by simultaneously adding the mixed salt solution and the alkali solution containing silicon to the coprecipitation medium.
The method for producing the fine particle composite oxide blue pigment as described in 1. 5. The method for producing a fine particle composite oxide blue pigment according to claim 3, wherein the pH at the time of coprecipitation is in the range of 7 to 10. 6. The method for producing a fine particle composite oxide blue pigment according to claim 3, wherein the firing temperature is in the range of 850 ° C. to 950 ° C.