JPH05221633A - Method forming acicular calcium carbonate particle - Google Patents

Abstract

PURPOSE:To obtain acicular calcium carbonate particles by reacting a three components system of calcium chloridemagnesium hydroxide-water with a carbon dioxide gas at >= a given temperature. CONSTITUTION:A aqueous solution or slurry into which a carbon dioxide gas is introduced is heated >=60 deg.C to carry out the reaction. The reaction, for example, is carried out by the following method. (A) magnesium hydroxide is added once or gradually to an aqueous solution of calcium chloride into which a carbon dioxide gas is being introduced. (B) Calcium chloride is added once or gradually to a slurry of magnesium hydroxide into which a carbon dioxide gas is being introduced. (C) A carbon dioxide gas is introduced calcium chloride, magnesium hydroxide and water in a mixed state (raw material solution). By the reaction, acicular calcium carbonate particles having 5-100mum long diameter and about 0.2-5mum short diameter are precipitated in the solution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing calcium carbonate, particularly acicular particle calcium carbonate, which is used as a filler, a reinforcing agent and the like in various industrial fields.

[0002]

2. Description of the Related Art Calcium carbonate is roughly classified into heavy calcium carbonate obtained by mechanically grinding limestone and synthetic calcium carbonate synthesized by a chemical method. Heavy calcium carbonate is obtained as amorphous particles, and the particle size thereof is adjusted to the target size by pulverization and classification.

As a method for producing synthetic calcium carbonate, there are mainly a "liquid-liquid" method and a "liquid-gas" method, and the "liquid-gas" method is industrially performed in Japan.

The "liquid-gas" method is typically a method in which carbon dioxide gas is blown into a calcium hydroxide slurry to cause a reaction, and the concentration of the calcium hydroxide slurry, the reaction temperature, the reaction method, the type and presence of additives, etc. By controlling the reaction conditions of, calcium carbonate of various particle sizes and shapes has been developed.

The inventors of the present invention first injected an aqueous solution of calcium hydroxide into water into which carbon dioxide was blown, so that the major axis was 5 to 100 μm and the minor axis was 0.2 μm by the “liquid-gas” method.
It was reported that acicular particles of calcium carbonate having a particle size of about 5 μm can be obtained (JP-A-62-278123).

On the other hand, the "liquid-liquid" method mainly involves reacting a solution containing carbonate ions (sodium carbonate aqueous solution, ammonium carbonate aqueous solution, etc.) with a calcium compound solution (calcium chloride aqueous solution, calcium acetate aqueous solution, etc.). To obtain calcium carbonate particles with a minor axis of 2-3 μm
A method for producing calcium carbonate crystals having m and a major axis of 30 to 60 μm is described in JP-A-59-203728.

[0007]

The object of the present invention is to produce acicular particulate calcium carbonate with high productivity by the "liquid-gas" method using carbon dioxide gas.

[0008]

The method for producing acicular particulate calcium carbonate of the present invention is characterized by reacting a three-component system of calcium chloride-magnesium hydroxide-water with carbon dioxide at 60 ° C or higher. ..

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the reaction of the ternary system of calcium chloride-magnesium hydroxide-water with carbon dioxide can be carried out, for example, by the following method. Method A: Magnesium hydroxide is added at once or gradually to an aqueous calcium chloride solution into which carbon dioxide gas is blown to generate acicular particles of calcium carbonate.

Method B: Calcium chloride is added to the magnesium hydroxide slurry in which carbon dioxide gas is blown at once or gradually to produce acicular acicular calcium carbonate.

Method C: Carbon dioxide gas is blown into a mixed state (raw material solution) of calcium chloride, magnesium hydroxide and water to produce acicular particles of calcium carbonate. The raw material liquid in which carbon dioxide gas is blown is obtained by reacting 1) calcium hydroxide and magnesium chloride and water, 2) calcium carbonate (limestone) and hydrochloric acid and magnesium hydroxide, or 3) calcium hydroxide, hydrochloric acid and magnesium hydroxide. Easy to get.

In the present invention, it is necessary to carry out the reaction by heating the aqueous solution or slurry into which carbon dioxide gas is blown to 60 ° C. or higher. If this temperature is too low, the infiltration rate of cubic calcite will increase.

As the carbon dioxide gas, only carbon dioxide gas may be blown or a mixed gas containing carbon dioxide gas may be blown.

Calcium chloride and magnesium hydroxide are generally added to the reaction system so that they are finally used in the reaction in approximately equimolar amounts.

By the above reaction, the major axis is 5 to 100 μm, the minor axis is
Needle-like calcium carbonate particles of about 0.2 to 5 μm are precipitated from the liquid.

[0016]

According to the present invention, needle-shaped calcium carbonate particles are formed by reacting a ternary system of calcium chloride-magnesium hydroxide-water with carbon dioxide gas, thereby injecting carbon dioxide gas by the "liquid-gas" method. Is obtained.

Moreover, this method is based on the above-mentioned JP-A-62-278123.
The productivity is more than several tens of times higher than that of the method described in the publication, and it is possible to realize a significant cost reduction, so it can be used in a wide range of applications such as synthetic resin compositions, paints and inks, and its expansion. Can be expected.

[0018]

【Example】

Example 1 Calcium chloride (1 mol) and magnesium hydroxide (1 mol)
Water is added to prepare 2 l (liter) of raw material liquid,
After heating to ~ 85 ° C, add carbon dioxide (1 l / min) 4
Blowing for a time to produce acicular particulate calcium carbonate.
The product is washed, filtered and dehydrated with a filter, and dried at about 100 ° C. using an electric dryer to obtain sample No. 1 acicular particles of calcium carbonate.

FIG. 1 shows an SEM (scanning electron microscope) observation photograph of Sample No. 1. The scale below the photograph represents a full scale of 20 μm and a scale of 2 μm. Further, FIG. 8 is an X-ray diffraction pattern of Sample No. 1, showing that it is mainly aragonite crystals.

The measurement conditions of X-ray diffraction are as follows (all common to the following examples). Target: Cu Filter: Ni Voltage / Current: 30KV / 15mA Full Scale: 2000Cps Time Const .: 1sec Scan. Speed: 2 ° / min Chart Speed: 20mm / min Div. Slit: 1 ° Rec. Slit: 0.2mm Scatt. Slit : 1 °

Example 2 Carbon dioxide gas (1 l / min) was blown in while stirring 80
0.5 mol of magnesium hydroxide (powder) was added at once to 2 l of an aqueous solution of calcium chloride (0.25 mol / l) at ˜85 ° C., and the mixture was reacted for 2 hours and 30 minutes to form acicular particles of calcium carbonate. Thereafter, needle-shaped particles of calcium carbonate of Sample No. 2 are obtained in the same manner as in Example 1.

FIG. 2 shows an SEM observation photograph of Sample No. 2. The scale below is full scale 20μm, 1
Represents a scale of 2 μm. Further, FIG. 9 is an X-ray diffraction pattern of Sample No. 2, showing that it is mainly aragonite crystals.

Example 3 Carbon dioxide gas (1 l / min) was blown in while stirring 80
1.5 mol of magnesium hydroxide was added at once to 2 l of an aqueous solution of calcium chloride (0.75 mol / l) at ˜85 ° C., and the mixture was reacted for 5 hours to form acicular particles of calcium carbonate. Thereafter, needle-shaped particles of calcium carbonate of Sample No. 3 are obtained in the same manner as in Example 1.

FIG. 3 shows an SEM observation photograph of Sample No. 3. The scale below is full scale 20μm, 1
Represents a scale of 2 μm. Further, FIG. 10 is an X-ray diffraction pattern of Sample No. 3, showing that it is mainly aragonite crystals.

Example 4 Carbon dioxide gas (1 l / min) was blown in while stirring 60
1 mol of magnesium hydroxide was added at once to 2 l of an aqueous calcium chloride solution (0.5 mol / l) at ˜65 ° C., and the mixture was reacted for 4 hours to form acicular particles of calcium carbonate. Thereafter, needle-shaped particles of calcium carbonate of Sample No. 4 are obtained in the same manner as in Example 1.

FIG. 4 shows an SEM observation photograph of Sample No. 4. The scale below is full scale 20μm, 1
Represents a scale of 2 μm. Further, FIG. 11 is an X-ray diffraction pattern of Sample No. 4, showing that it is mainly aragonite crystals.

Example 5 Carbon dioxide gas (1 l / min) was blown in with stirring 80
1 mol of magnesium hydroxide was added to 2 l of an aqueous calcium chloride solution (0.5 mol / l) at ˜85 ° C. for 1/6 mol per 1 hour, and the mixture was reacted for 6 hours to form needle-shaped calcium carbonate particles. Thereafter, needle-like particles of sample No. 5, calcium carbonate are obtained in the same manner as in Example 1.

FIG. 5 shows an SEM observation photograph of Sample No. 5. The scale below is full scale 20μm, 1
Represents a scale of 2 μm. Further, FIG. 12 is an X-ray diffraction pattern of Sample No. 5, showing that it is mainly aragonite crystals.

Example 6 Carbon dioxide gas (1 l / min) was blown in while stirring 80
~ 85 ℃ magnesium hydroxide slurry (0.25mol / l) 2l
Then, 0.5 mol of calcium chloride is added to each of 1/12 mol per 1 hour, and the mixture is reacted for 6 hours to generate acicular acicular calcium carbonate. Thereafter, needle-shaped particles of calcium carbonate of Sample No. 6 are obtained in the same manner as in Example 1.

FIG. 6 shows an SEM observation photograph of Sample No. 6. The scale below is full scale 20μm, 1
Represents a scale of 2 μm. Further, FIG. 13 is an X-ray diffraction pattern of Sample No. 6, showing that it is mainly aragonite crystals.

Example 7 0.5 mol of calcium hydroxide was added at once to 2 l of an aqueous magnesium chloride solution (0.37 mol / l), heated to 80 to 85 ° C., and carbon dioxide (0.1 l / min) was added to 6 while stirring. Blowing for a time to produce acicular particulate calcium carbonate. Wash the product,
It is filtered and dehydrated with a filter, and about 100 using an electric dryer.
The sample is dried at ℃ to obtain sample No. 7 acicular particles of calcium carbonate.

FIG. 13 shows an SEM observation photograph of Sample No. 7. The scale below the photo is full scale 50 μm, 1
Represents a scale of 5 μm. Further, FIG. 14 is an X-ray diffraction pattern of Sample No. 7, showing that it is mainly aragonite crystals.

[0033]

[Brief description of drawings]

FIG. 1 is a SEM photograph (particle structure) of acicular particles of calcium carbonate of Sample No. 1.

FIG. 2 is an SEM photograph of sample No. 2 acicular particles of calcium carbonate.

FIG. 3 is a SEM photograph of acicular particle calcium carbonate of Sample No. 3.

FIG. 4 is a SEM photograph of acicular particles of sample No. 4, calcium carbonate.

FIG. 5 is a SEM photograph of acicular particles of sample No. 5, calcium carbonate.

FIG. 6 is an SEM photograph of sample No. 6 acicular particles of calcium carbonate.

FIG. 7 is a SEM photograph of acicular particles of sample No. 7, calcium carbonate.

FIG. 8 is a chart showing an X-ray diffraction pattern of processing material No. 1. In each of the following figures, A shows a peak of an aragonite crystal, and C shows a peak of a calcite crystal.

FIG. 9 is a chart showing an X-ray diffraction pattern of Sample No. 2.

FIG. 10 is a chart showing an X-ray diffraction pattern of Sample No. 3.

FIG. 11 is a chart showing an X-ray diffraction pattern of Sample No. 4.

FIG. 12 is a chart showing an X-ray diffraction pattern of Sample No. 5.

FIG. 13 is a chart showing an X-ray diffraction pattern of Sample No. 6.

FIG. 14 is a chart showing an X-ray diffraction pattern of Sample No. 7.

Claims (1)

[Claims] 1. Calcium chloride-magnesium hydroxide-
A method for producing acicular particles of calcium carbonate, which comprises reacting a three-component system of water with carbon dioxide at 60 ° C or higher.