JPS6033765B2 - Calcium carbonate production method - Google Patents

Description

Detailed Description of the Invention The present invention relates to a method for producing calcium carbonate, and more specifically, the present invention relates to a method for producing calcium carbonate.
．． The present invention relates to a method for producing paper cone-shaped calcium carbonate having a diameter of 5 to 1.0 rm.

More particularly, the present invention provides a concentration of 10 to 2% by weight (% means % by weight unless otherwise specified) and a temperature of 20 to 50 oo.
To a suspension of calcium hydroxide, 1 to 1 part of water glass or silica sol (calculated as Si02) is added to 10 parts by weight of solid calcium hydroxide (all parts hereinafter refer to parts by weight), and the concentration is 15 to 33% by volume of carbon dioxide gas
By introducing Ca(OH) at a flow rate of 150 minutes or more under pressure of 10 kg/pillow (gauge pressure),
A method for producing highly dispersible, bell-shaped calcium carbonate with a short axis of 0.05 to 0.2 fm and a long axis of 0.5 to 1.0 fm, and the surface of the particles of the calcium carbonate thus obtained Alternatively, the present invention relates to a method for producing calcium carbonate that is treated with an inorganic modifying material. Methods for producing precipitated calcium carbonate include carbonation by reaction of milk of lime with carbon dioxide gas;
A carbonate solution synthesis method is known in which calcium chloride and a water-soluble carbonate are reacted in a solution state.

Currently, industrially, the carbon dioxide gasification method is used to produce fine cubic calcium carbonate with an average particle size of 1.0 fm and a major axis of 1.0 mm.
Cone-shaped or acicular calcium carbonate, which is larger than a French m, has been produced and is widely used in paper, rubber, plastic, paint, ink, and other industries. When calcium carbonate is used as a filler for coated paper, the finest particles without surface treatment and without agglomeration are considered optimal in terms of gloss, opacity, pickability and printability.

In addition, in the coating, coating, and plastic coating industries, the surface of calcium carbonate is modified with various organic or inorganic substances to improve its dispersibility and improve its affinity with the matrix or vehicle. It is desired for its properties such as quality and gloss. In order to meet these demands, surface-modified cubic calcium carbonate having a particle size of 0.05 to 0.5 m is currently mainly used. On the other hand, when the major axis of spindle-shaped particles becomes less than 1 m, characteristics that are not found in fine cubic particles appear, and various studies have been conducted on their production methods, but there are difficulties in producing them stably and uniformly. Regarding the agglomeration mechanism, fine cubic particles predominate in agglomeration during drying, while conical particles are mostly agglomerated due to irregular crystal growth during calcium carbonate formation, and are not suitable for industrial use. From this point of view, it is more difficult than the production of cubic particles.

The present invention solves these difficulties all at once, and makes it easy to mass-produce spindle-shaped particles with less cohesiveness during generation and drying. The present invention provides a method for producing calcium carbonate, which has extremely useful properties in terms of reinforcing properties and other applied physical properties, and a method for producing surface-modified products thereof.

The present invention will be explained in more detail.

Conventionally, the conditions for producing spindle-shaped calcium carbonate with a short axis of 0.2 to 0.5 m and a long axis of 1 to 4 rm are 1 French m.
Contrary to the manufacturing conditions for fine cubic calcium carbonate below, normally milk of lime with a concentration of 5% or higher and carbon dioxide gas at a temperature of 20q0 or higher is heated under normal pressure at a flow rate of 50 m/min/k9Ca (
The carbonation reaction is carried out slowly at OH) 2 or less, and the main objective is to select conditions that will increase the growth of crystals in the - direction as much as possible, but the inventors have determined that the concentration and temperature of the milk of lime 10 to 20, which is the manufacturing condition range for large grade cone-shaped particles.
% and 20 to 50oo, and the carbon dioxide flow rate was selected as a composite condition of 150 mm/k9Ca(OH)2 or more with a concentration of 15 to 3% by volume, which is the basic condition for producing fine cubic particles. Furthermore, 1 to 10 kg/c of fin (gauge pressure) was added to a calcium hydroxide suspension in which 1 to 1 part of water glass or silica sol was added to 100 parts of calcium hydroxide.
By introducing carbon dioxide gas under the pressure of
The present invention was completed by discovering that it is possible to produce fine woven coin-shaped calcium carbonate having a diameter of ~0.2 m and a major axis of 0.5 to 1.0 #m and having very good dispersibility.

That is, the present invention has a concentration of 10-2% by weight and a temperature of 20-5% by weight.
To a 0G0 calcium hydroxide suspension, add water glass or silica sol in an amount of 1 to 10 parts based on S;
/ ground (gauge pressure) under pressure of 150 so/min/k9Ca (
OH) By introducing carbon dioxide gas at a flow rate of 2 or more, the short axis is 0.05.
A method for producing calcium carbonate, characterized by obtaining spindle-shaped calcium carbonate with a length of 0.2 French m and a major axis of 0.5 to 1.0 French m, and a concentration of 10 to 2% by weight and a temperature of 20 to 50 o
Add water glass or silica sol in an amount of 1 to 10 parts based on the weight of 10 parts by weight of solid calcium hydroxide to the calcium hydroxide suspension of 1 to 10 k9/c.
150 so/min/k9Ca(O
H) Carbon dioxide gas with a concentration of 15 to 35% by volume is introduced at a flow rate of 2 or more, and the short axis is 0.05 to 0.2 fm and the long axis is 0.5 to 1.
The present invention provides a method for producing calcium carbonate, which is characterized in that paper spindle-shaped calcium carbonate of 0 rm is produced, and the surface of the thus obtained calcium carbonate particles is treated with an organic or inorganic refining agent.

At this time, if the concentration of milk of lime is less than 10% and the temperature is less than 20 oo, even if other conditions are within the specified range of the present invention.
If fine calcium carbonate of 1 French m or less is formed, and the milk of lime concentration is 20% and the temperature exceeds 5000, aggregates of spindle-shaped particles are obtained and the desired easily dispersible calcium carbonate particles cannot be obtained. do not have.

In addition, if the amount of water glass or silica sol added is less than 1 part based on Si0 odor compared to 10 parts of solid calcium hydroxide, the major axis will exceed 1.0 m, and if it exceeds 10 parts, the particle will grow. Perhaps because it is suppressed too much, the major axis is 0.5 French m.
If it becomes less than Note that the pressure of carbon dioxide during the reaction is one of the most important conditions related to the present invention, but if it is less than lk9/c (gauge pressure), the major axis is 1
．． 0 French m, short axis exceeds 0.2 French m, 10k9/c skin (
(gauge pressure), a mixture of fine cubic and key-shaped particles is obtained. The organic modified molecules used in the method of the present invention include, for example, alkali metal salts such as fatty acids or resin acids, alkylarylsulfonic acids or their alkali metal salts, anionic surfactants such as higher alcohol sulfates, and polymers that impart hydrophilicity. These include alkali metal salts of acrylic acid, alkali metal salts of polycarboxylic acids of copolymers of maleic acid and imbutylene, styrene, or vinyl acetate, or partial ester half-amides thereof, and inorganic modifiers include hydrogen fluoride, These include sulfur dioxide gas, phosphoric anhydride, chlorides or fluorides of metals such as titanium, aluminum, zinc, and silicon.

As described above, by carrying out the carbonation reaction within the above-mentioned condition ranges of the present invention, it is possible to achieve the desired minor diameter of 0.05 to 0.05.
It is possible to produce spindle-shaped calcium carbonate having a length of 0.2 French m and a major axis of 0.5 to 1.0 m, with very good dispersibility.

The product produced by the method of the present invention is extremely useful as a filler for coated papers or water-based paints, and the products further treated with organic or inorganic acids can be used as fillers for rubber, plastics, and paints due to their easily dispersible properties. Because of its excellent affinity with the metal, it can exhibit properties such as high reinforcing properties and gloss.

*The present invention will be explained in more detail below with reference to Examples.

Example 1 Calcium hydroxide suspension of 3000 750 at 10% concentration
0k9, No. 3 water glass is 37.5k in Si02 minutes
After adding 9.0% of carbon dioxide by volume, add 3k9 of carbon dioxide gas at 30°C.
A carbonation reaction is carried out by introducing carbon dioxide gas with a concentration of 2% in customer service volume at 170〆/min/k9Ca(OH)2 under pressure into a /c marsh (gauge pressure), followed by dehydration with a centrifuge, drying, and crushing. By classifying, a spindle-shaped calcium carbonate lt having a minor axis of 0.10 m and a major axis of 0.7 rm was obtained.

Examples 2 and 3 and Comparative Examples 1 to 4 Calcium carbonate having different particle sizes was obtained in the same manner as in Example 1, with the conditions changed as shown in Table 1.

The results are shown in Table 1. Table 1 Application Example 1 The analysis value (%) of particles of 2 French m or less measured with "Micron Photosizer" manufactured by Seishin Enterprises of Examples 1 to 3 and Comparative Examples 1 to 4 and the coated paper application data are shown in Table 1. It is shown in Table 2.

Formulation for coated paper: Apply the coating color of Kamigami's formulation by hand to commercially available high-quality paper using a coping bar, dry at room temperature, then season.
The test was conducted at a coating amount of 5 days/day.

The test method is as follows: Glossiness; JISP8142 Whiteness; JISP8123 Opacity; JISP8138 10T pick: Using picking oil "L", lO
Measured using a T printing aptitude tester (manufactured by Kumagai Riki) Table 2 Example 4 The calcium carbonate suspension of Example 1 was adjusted to a concentration of 15%, and carbon dioxide gas at a concentration of 2% was introduced and adjusted separately. At 9000 ml, 2.0 parts of 10% sodium fatty acid was added to 10 parts of solid calcium carbonate in terms of pure content, and carbon dioxide gas was continued for 18 minutes.

Surface-modified calcium carbonate was obtained by dehydrating, drying, crushing, and classifying the obtained product. Application example 2 Examples 1 and 4 and commercially available calcium carbonate (minor axis 0
．． 3#, paper cone-shaped particles with a major diameter of 2.5 mm) 5 Bogun and 100 parts of polypropylelene resin (trade name "Noprene WIOI", manufactured by Sumitomo Chemical Industries) were premixed, and then 1
After rolling and filling for a while, it is taken out in a sheet form, made into pellets with a beletizer, and ASTed at 230 qoo0 with an injection molding machine.
An M standard test piece was prepared, and its whiteness, surface gloss, tensile strength, and bending strength were measured using the following methods.

Whiteness; JISP8123 (45o-oo) surface gloss;
ASTM D523 (60o -60o) tensile strength; AS
TMD638 bending strength; ASTM D790 test results are shown in Table 3.

From the results in Table 3, it can be seen that the polypropylene resin treated with the modifier (Example 4) provides significantly superior physical properties to the polypropylene resin compared to the untreated one (Example 1 and comparative commercial products). .

As explained in detail above, the spindle-shaped calcium carbonate produced by the method of the present invention does not have the disadvantages of conventional cubic and bell-shaped calcium carbonate, and has the advantages of both, and is suitable for paper, rubber, etc. It is clear that it has extremely excellent properties as a filler for plastics and paints.

Claims (1)

[Claims] 1. To a calcium hydroxide suspension having a concentration of 10 to 20% by weight and a temperature of 20 to 50°C, water glass is added in an amount of 1 to 10 parts in terms of SiO_2 per 100 parts by weight of calcium hydroxide solid content. Or add silica sol and apply 1 to 10 kg/cm^2 (
150l/min/kgCa(OH) under pressure (gauge pressure)
By introducing carbon dioxide gas with a concentration of 15 to 35% by volume at a flow rate of _2 or more, the short axis is 0.05 to 0.2 μm and the long axis is 0.5 to 1.0
A method for producing calcium carbonate, characterized by obtaining micron spindle-shaped calcium carbonate. 2. To a calcium hydroxide suspension having a concentration of 10 to 20% by weight and a temperature of 20 to 50°C, add water glass or silica sol in an amount of 1 to 10 parts in terms of SiO_2 per 100 parts by weight of calcium hydroxide solid content, 1~10kg/cm^2(
150l/min/kgCa(OH) under pressure (gauge pressure)
By introducing carbon dioxide gas with a concentration of 15 to 35% by volume at a flow rate of _2 or more, the short axis is 0.05 to 0.2 μm and the long axis is 0.5 to 1.0
A method for producing calcium carbonate, which comprises producing micrometer spindle-shaped calcium carbonate and treating the surface of the thus obtained calcium carbonate particles with an organic or inorganic modifier.