JPH0822747B2 - Method for producing fine particle composite oxide green pigment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing a fine particle composite oxide green pigment having excellent transparency and dispersibility, which is useful as a colorant for paints, synthetic resins and ceramics. Regarding

[Prior Art] A composite oxide green pigment is widely known as an inorganic pigment having excellent weather resistance and heat resistance, and is widely used, for example, as a colorant for paints and synthetic resins, and a colorant for ceramics.

The complex oxide green pigment is a spinel type compound composed of oxides of cobalt, zinc, nickel and titanium, and is manufactured mainly by a dry method. Also,
In the wet method, a method for producing a green inorganic pigment has already been disclosed (JP-A-52)
-74599), the applicant filed a patent application. This causes the other three metal components to co-precipitate with titanium oxide or metatitanic acid dispersed in an aqueous medium, but it is difficult to obtain a transparent fine particle type by such a conventional method. Is.

[Problems to be Solved by the Invention] The dry method is to mix oxides of cobalt, zinc, nickel, and titanium, co-exist with a flux and burn at high temperature, and then crush the sintered particles with a powerful crusher. However, as long as each constituent oxide is not a fine particle, the product after firing is not likely to be a transparent fine particle, and even if such a fine particle is present, it can be sintered and pulverized during firing. Requires a lot of energy.

On the other hand, in the case of the wet method, titanium oxide or metatitanic acid, which has a large proportion of constituents, is used as a base and has a size that does not cause aggregation during drying. Therefore, no fine particle type product has been obtained. Further, when titanium is co-precipitated as a metal salt such as titanium tetrachloride, it is difficult to obtain sufficient color and agglomerate when dried, so it is difficult to pulverize it by firing to make it a pigment. Is.

[Means for Solving the Problems] The present invention has been earnestly researched in order to meet the above-mentioned demands, and as a result, when hydrogen peroxide or peroxoic acid and peroxoic acid salt are added when a titanium aqueous solution is used in a wet precipitation method, it is desired. It has been found that the characteristics described above can be satisfied.

That is, the present invention, when adding an aqueous solution containing titanium to an aqueous solution of each salt of cobalt, zinc and nickel in the wet precipitation method, hydrogen peroxide or peroxo acid and peroxo acid salt are also added at the same time to obtain a mixed solution, which is used as a precipitating agent. A method for producing a fine particle composite oxide green pigment, which comprises co-precipitating each element by simultaneous addition using an alkaline aqueous solution such as caustic soda, filtering, washing with water, drying and firing. The fine particle transparent composite oxide green pigment thus obtained is expected to be applied to, for example, transparent paints, transparent thin films, printing inks, cosmetics, phosphors, abrasives, etc. by utilizing its characteristics.

[Operation] Titanium peroxide is generated by adding hydrogen peroxide or peroxo acid and peroxo acid salt to an aqueous solution containing titanium, and when this is precipitated, it precipitates as fine particles and aggregates having a certain size. Therefore, even though it is fine particles after drying, it rises softly as a pigment precursor, and since the precipitation of each component is performed uniformly, sufficient color is developed even by firing at a relatively low temperature, and a soft and transparent composite oxide A green pigment is obtained.

[Examples] Next, preferred embodiments of the present invention will be described in more detail.

The salts of each constituent element other than titanium used in the present invention include sulfates, nitrates, carbonates, chlorides, acetates, etc., which are conventionally used when producing a composite oxide green pigment. You can Further, in the case of titanium, a reagent such as titanium tetrachloride or titanyl sulfate or an industrial raw material can be used, and a reagent or an industrial raw material generally used in hydrogen peroxide or peroxo acid and peroxo acid salt to be added can also be used. .

In the above, the composition ratio of each component is the best in terms of molar ratio of metal, cobalt: zinc: nickel: titanium = 1: 1: 2: 2, and in this case, green coloration is good. However, the transparency is not significantly deteriorated unless it deviates significantly from this ratio. According to the results of the research, when the amount of titanium is large, it becomes slightly whitish and the transparency is deteriorated, and when it is small, the amount of dullness tends to increase.

The metal salts of the respective constituent elements as described above are dissolved in water to form a mixed aqueous solution, and the concentration thereof is appropriately about 5 to 50% by weight as a whole in terms of molar ratio as described above.

Further, hydrogen peroxide or a peroxo acid and a peroxo acid salt aqueous solution is added to the thus mixed aqueous solution to prepare a mixed aqueous solution containing a metal salt as a constituent component. According to the detailed study by the present inventors, at this time, the hydrogen peroxide or the peroxo acid and the peroxo acid salt aqueous solution were added, so that the mixed aqueous solution changed from slightly greenish dark brown to dark red with some heat generation. And the peroxide of titanium is generated. The amount added at this time was 0.05 per 1 mol of titanium in the case of hydrogen peroxide in order to obtain a transparent composite oxide green pigment.
The range of mol to 1.3 mol is suitable, and if it is less than this range, clear transparency cannot be obtained. On the other hand, if the amount is more than this range, the hydrogen peroxide is wasted and excessive hydrogen peroxide is discharged to the outside of the system by the mist and the washing time becomes long, so that the working conditions are deteriorated.

The thus-obtained mixed aqueous solution is simultaneously added dropwise to preliminarily prepared precipitation water using an alkaline aqueous solution such as caustic soda as a precipitant. Although the reaction concentration at this time does not particularly affect the transparency, it is preferably 0.05 mol / -0.4 mol / (based on the metal of titanium) in view of working conditions. In addition, if the synthesis temperature is in the range usually performed, that is, in the range of 0 ° C to 100 ° C, the effect can be sufficiently exhibited. However, when the temperature exceeds 80 ° C, the transparency tends to be slightly impaired. Moreover, the pH at the time of synthesis at this time may be on the alkaline side of 7 or more,
Tends to become dull as it shifts to the alkaline side. When the pH is lower than 7, the hydroxides of nickel, cobalt and zinc are less likely to precipitate, which adversely affects the color development.

In this way, a precipitate was formed with stirring for 30 minutes to 1 hour, and then about 1 to complete the reaction.
The precipitation reaction can be completed by aging for about the time.

Next, the precipitated coprecipitate is filtered to have a water content of about 40% to 80%, which is dried at a temperature of about 100 ° C to 120 ° C, and this is dried in an oxidizing atmosphere at 600 ° C to 1000%. ℃
The fine particle composite oxide green pigment of the present invention can be obtained by causing color development by firing at the temperature of 30 minutes to 1 hour.

The fine particle composite oxide green pigment according to the present invention thus obtained was transparent and had a deep color tone and had good dispersibility in paints, etc., as compared with the conventional wet method. .

Example 1 83.23 parts of nickel chloride hexahydrate, cobalt nitrate hexahydrate 50.
93 parts, 50.32 parts of zinc sulfate heptahydrate and 100.45 parts of titanium tetrachloride aqueous solution having a titanium content of 16.7% by weight are weighed and dissolved in 830 parts of water, and then 70 parts of industrial 35% by weight hydrogen peroxide are added thereto. The aqueous solution immediately changes from dark greenish brown to dark red with some exotherm. Next, 87.5 parts of caustic soda as a precipitant is weighed and water is added to make about 1000 parts.

2400 parts of precipitating water prepared in advance is heated and maintained at about 45 ° C. with a gas burner, an electric heater, etc., and a mixed salt aqueous solution and a caustic soda aqueous solution are simultaneously added dropwise to this, and the precipitation reaction is performed for about 30 minutes to 1 hour. At this time, be careful that the pH is 7, and keep the temperature of the aqueous solution at 45 ° C. When the dripping is complete, to ensure complete precipitation
Increase the pH to about 8 and continue to increase the temperature of the aqueous solution.
Aging is performed for about 1 hour while maintaining the temperature at 45 ° C.

Next, when the aging is completed, the product is taken out, thoroughly washed with water by decantation to wash away the residual salt, and filtered. Then, it is dried at a temperature of 100 to 120 ° C. for 12 hours or more.

The dried pigment precursor is baked at 800 ° C. for 1 hour in an oxidizing atmosphere. The baked product was then dispersed with a paint shaker using melamine / alkyd resin and PHR40, and the color was observed on an art paper with a black belt by a 6 mil applicator.

The pigment thus obtained, when compared with conventional products,
It was transparent, had a deep color tone, and had good dispersibility.

Example 2 82.95 parts of titanyl sulfate dihydrate having a titanium content of 33.7% by weight was added to 930 parts of water prepared in advance, and the mixture was stirred to about 1 part.
Let stand for a while to dissolve completely. Next, the same amounts of nickel chloride hexahydrate, cobalt nitrate hexahydrate and zinc sulfate heptahydrate as in Example 1 are measured and dissolved in a titanium aqueous solution.

 Hereinafter, the same method as in Example 1 is performed.

The pigment thus obtained was transparent, had a deep color tone and had good dispersibility as in Example 1.

Comparative Example 1 A series of operations similar to those in Example 1 is performed except that hydrogen peroxide is not added.

The pigment thus obtained did not have sufficient color development as compared with Example 1 and had a whitish feeling overall and a poor transparency. Moreover, the same tendency was exhibited when compared with the conventional product.

Comparative Example 2 A series of operations similar to those in Example 2 is performed except that hydrogen peroxide is not added.

The product thus obtained showed the same tendency as in Comparative Example 1.

 The following results are summarized in Table 1.

[Effects of the Invention] According to the present invention, an aqueous solution of a titanium compound is added to an aqueous solution of each salt of cobalt, zinc and nickel to form a mixed solution, and an alkaline aqueous solution is added thereto to coprecipitate the mixed solution. Since at least one selected from hydrogen peroxide, peroxo acid and peroxo acid salt is added, coprecipitation of hydroxides of cobalt, zinc, nickel and titanium is carried out uniformly and dehydration of the coprecipitate is easy. In addition, a transparent and deep green pigment can be obtained even by firing at a relatively low temperature.

Since the composite oxide green pigment of the present invention is a soft particle, it can be easily pulverized and has excellent dispersibility.

Claims (4)

[Claims] 1. A coprecipitate obtained by adding at least one selected from hydrogen peroxide, a peroxo acid and a peroxo acid salt to a mixed aqueous solution of a nickel salt, a cobalt salt, a zinc salt and a titanium compound, and then adding an alkaline aqueous solution. And a step of firing the coprecipitate to produce a fine particle composite oxide green pigment. 2. The method for producing a fine particle composite oxide green pigment according to claim 1, wherein the peroxo acid is peroxosulfuric acid, peroxonitric acid, peroxocarbonic acid, peroxoboric acid and peroxophosphoric acid. 3. The method for producing a fine particle composite oxide green pigment according to claim 1, wherein the peroxo acid salt is an alkali metal salt, an alkaline earth metal salt and an ammonium salt. 4. The method for producing a fine particle composite oxide green pigment according to claim 1, wherein the firing temperature is 600 ° C. or higher.