JP3058255B2 - Method for producing precipitated calcium carbonate - Google Patents

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 precipitated calcium carbonate which is fine, has little secondary aggregation, and has good dispersibility.

[0002]

2. Description of the Related Art At present, a carbon dioxide method is widely used as an industrial production method of precipitated calcium carbonate. According to the size of the primary particles, calcium carbonate produced in this manner is subjected to various surface treatment agents of inorganic or organic type on the particle surface in order to further improve physical properties at the time of compounding, It is compounded in rubber, plastic, paper, paint, etc., and is widely used in large quantities. However, the precipitated calcium carbonate produced by the carbon dioxide method originally has a strong cohesive force between particles, and a large number of primary particles are aggregated to form a large secondary aggregate. .
Those having a particle size of 2 μm or less have a particularly strong cohesive force, and it is impossible to eliminate secondary aggregates while maintaining the initial primary particle diameter even when a large amount of energy is used.

When precipitated calcium carbonate containing a large number of such secondary aggregates is mixed with rubber, plastic, paper, paint, etc., the secondary aggregated particles behave like large primary particles, resulting in poor dispersion. Physical properties such as a decrease in strength, a decrease in gloss, and a decrease in viscosity are caused, and various compounding effects that are originally expected for fine primary particles cannot be obtained. Similarly,
Even if a surface treatment of various kinds of inorganic or organic surface treating agents is performed on the precipitated calcium carbonate containing a large number of such secondary aggregates, only the surface treatment of the secondary aggregated particles does not exert a sufficient effect. .

Conventionally, in order to disperse these secondary aggregates, a step of aging a calcium carbonate slurry under conditions such as heating and stirring has been used. However, in this dispersion method, the primary particles grow several times as large as the original particles as the dispersion of each particle progresses. That is, in the dispersion step by aging, maintaining the fine primary particle diameter immediately after the completion of the carbonation reaction and dispersing these aggregates are contradictory events. As described above, in the prior art, it was impossible to obtain a dispersed state as close as possible to the primary particles as much as possible in the state of fine particles that are expected to be widely used industrially.

[0005]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention is a method for producing calcium carbonate which is finer and has better dispersibility than conventional precipitated calcium carbonate. That is, the present invention provides a method for producing precipitated calcium carbonate, in which primary particles are dispersed in a good dispersion state without growing as much as possible, even if the same maturation step as before is used to disperse the aggregated particles of calcium carbonate. Things.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, by adding a specific substance to carry out a carbonation reaction, it is possible to obtain a fine and well-dispersed carbon dioxide by precipitation. A method for producing calcium has been found. That is, in the present invention, when carbon dioxide gas is blown into an aqueous calcium hydroxide suspension (hereinafter referred to as lime milk) to produce calcium carbonate, the aqueous calcium hydroxide suspension is coordinated with metal ions. A method for producing precipitated calcium carbonate, comprising adding a complex-forming substance (hereinafter, referred to as a complex-forming substance) to generate calcium carbonate by a carbonation reaction, and then aging the calcium carbonate. The contents.

Hereinafter, the production method of the present invention will be described more specifically. The lime milk concentration is 3.5 to 19.3% (% by weight,
The same applies hereinafter), preferably 6.1 to 13.3% of lime milk, to which a complex-forming substance is added.

The complex-forming substance used in the present invention includes hydroxycarboxylic acids such as citric acid, oxalic acid and malic acid and their alkali metal salts, alkaline earth metal salts and ammonium salts; and polyhydroxy acids such as gluconic acid and tartaric acid. Carboxylic acids and their alkali metal salts, alkaline earth metal salts and ammonium salts; aminopolycarboxylic acids such as iminodiacetic acid, ethylenediaminetetraacetic acid and nitrilotriacetic acid and their alkali metal salts, alkaline earth metal salts and ammonium salts; hexametaphosphoric acid, Polyphosphoric acid such as tripolyphosphoric acid and its alkali metal salts, alkaline earth metal salts and ammonium salts; amino acids such as glutamic acid and aspartic acid and its alkali metal salts, alkaline earth metal salts and ammonium salts; acetylacetone, methyl acetoacetate, acetoacetate Such as allyl acetate Emissions, etc. can be mentioned, which may be used alone or in combination of two or more.

The complex-forming substance is preferably 0.1 to 10%, more preferably 0.3 to 5%, based on calcium hydroxide.
% Is added. Less than 0.1% is not so effective and 1
Exceeding 0% is not only unfavorable in terms of cost, but also
Agglomeration tends to be too strong and difficult to disperse. The timing of addition may be either before or during the carbonation reaction, or may be added both before and during the reaction.

[0010] Carbon dioxide gas is passed through this lime milk to produce a calcium carbonate slurry. As for the condition at this time, the lime milk concentration is preferably 3.5 to 19.3%. If it is less than 3.5%, the cost is industrially high, which is not preferable.
If it exceeds 3%, the generated calcium carbonate particles are undesirably large. The reaction initiation temperature is preferably from 8 to 30C. If the temperature is lower than 8 ° C., it is not preferable because the cost is industrially high, and if it is higher than 30 ° C., the generated calcium carbonate particles are undesirably large. CO2 flow rate is 40
~ 1800 L / hr is preferred. If it is less than 40 lLhr, the generated calcium carbonate particles become large, which is not preferable.
If it exceeds 800 L / hr, the cost becomes industrially high, which is not preferable.

The calcium carbonate slurry obtained as described above is used at a liquid temperature of 20 for the purpose of dispersing calcium carbonate particles.
Stir at ~ 70 ° C to obtain a calcium carbonate slurry that has hardly grown from the primary particle size of the original aggregate. If the temperature at this time is lower than 20 ° C., it takes a long time for dispersion, which is not preferable. If it is higher than 70 ° C., the cost is industrially high, which is not preferable. The stirring conditions are preferably 5 rpm or more, more preferably 5 to 360 rpm. The ripening time becomes shorter as the stirring power becomes larger, but if it exceeds 360 rpm, the cost increases, which is not preferable, and if it is less than 5 rpm, the ripening period becomes longer, which is not preferable in terms of cost.

Whether or not the particles are dispersed by the production method of the present invention can be confirmed from a particle size distribution meter, an electron microscope, a thickening state of the calcium carbonate slurry over time, and the like. On the other hand, to confirm that the particles hardly grow in the dispersion process and exist in the state of fine particles, measurement of the specific surface area by the BET method, electron micrographs, and the like are appropriate. According to the conventional aging method under stirring and heating conditions, when the specific surface area of the particles immediately after carbonation has a particle diameter of, for example, about 50 m ² / g as measured by the BET method, when the particles are dispersed by aging, 2
It will be less than 0 m ² / g. That is, the particles grow due to ripening, and the particle diameter increases. On the other hand, according to the method of the present invention, even if a conventional aging method is used, the specific surface area of the BET method can be maintained at 40 m ² / g or more. Further, the dispersed state of the particles is equal to or higher than that obtained by a conventional aging method. As a method of dispersing the aggregated particles, in addition to the aging method by stirring, heating and the like described above, a wet pulverizing method using a wet mill using glass beads, an ultrasonic dispersion method, and repeatedly dehydrating and adding water while removing alkalis. Although there are methods and the like, a suitable method may be used as appropriate according to the situation.

[0013] In the production method of the present invention, as a method for further suppressing the growth of particles, a phosphorus-containing substance is added to the calcium carbonate slurry immediately after the above-mentioned compounding, the mixture is aged under the above conditions, and the dispersed carbonic acid without particle growth is dispersed. A method of obtaining a calcium slurry is exemplified. Examples of the phosphorus-containing substance include phosphoric acid, phosphorous acid, phosphonic acid, derivatives thereof, alkali metal salts, alkaline earth metal salts, ammonium salts, and the like. These may be used alone or in combination of two or more. Can be The amount of addition is 0.1 to calcium carbonate.
About 01 to 0.6% is preferable. If it is less than 0.01%, the particle growth rate of calcium carbonate increases, and the particle growth becomes remarkable at the same time as the dispersion. If it exceeds 0.6%, the particle growth is suppressed but the dispersion tends to be slow, and the cost tends to be low. It is also not preferable.

The fine particle calcium carbonate obtained by the present invention can be used as a thickener for paints, a sealing material, a thixotropy-imparting agent for vinyl chloride paste sol, a rubber reinforcing agent, a plastic reinforcing agent, an ultraviolet absorber in various fields, It is suitable for use as a coating material for coated paper, a pigment for printing ink, a carrier for agricultural chemicals, a toner for ink jet paper, and a cosmetic raw material.

[0015]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 10% trisodium citrate was added to 10% lime milk at a temperature of 10 ° C. and 11.8% lime milk in an amount of 8% based on calcium hydroxide.
Carbon dioxide gas was passed at a flow rate of 0 L / hr to produce calcium carbonate. Then, the calcium carbonate slurry was stirred at a temperature of 45 to 50 ° C. for 2 days (180 rpm) to give a BET specific surface area of 50 m ² having an average particle diameter of 0.44 μm.
/ g of calcium carbonate slur was obtained. Table 1 shows the reaction conditions and results.

EXAMPLE 2 10% trisodium citrate was added to lime milk at a temperature of 10 ° C. and a concentration of 11.8%, and 0.5% to calcium hydroxide.
1 kg / kg of calcium hydroxide
Carbon dioxide gas was passed at a flow rate of 700 L / hr to produce calcium carbonate. Next, this calcium carbonate slurry was stirred at a temperature of 45 to 50 ° C. for 2 days (180 rpm) to obtain a BET specific surface area 2 having an average particle size of 0.34 μm.
8 m ² / g of calcium carbonate slur was obtained. Table 1 shows the reaction conditions and results.

Example 3 10% trisodium citrate was added to 11.8% lime milk at a temperature of 10 ° C. and 1.0% to calcium hydroxide.
And add 4 g / kg of calcium hydroxide to the slurry.
Carbon dioxide gas was passed at a flow rate of 0 L / hr to produce calcium carbonate. Next, this calcium carbonate slurry was stirred at a temperature of 45 to 50 ° C. for 2 days (180 rpm) to give a BET specific surface area of 28 m ² having an average particle size of 0.37 μm.
/ g of calcium carbonate slur was obtained. Table 1 shows the reaction conditions and results.

Example 4 10% trisodium citrate was added to lime milk at a temperature of 10 ° C. and a concentration of 11.8%, and 1.0% to calcium hydroxide.
And add 4 g / kg of calcium hydroxide to the slurry.
Carbon dioxide gas was passed at a flow rate of 0 L / hr to produce calcium carbonate. Subsequently, 0.3% of phosphoric acid was added to the calcium carbonate slurry, and the mixture was stirred at a temperature of 45 to 50 ° C. for 2 days (180 rpm) to obtain an average particle diameter of 0.37 μm.
Of calcium carbonate slurries having a BET specific surface area of 40 m ² / g. Table 1 shows the reaction conditions and results.

Example 5 To a lime milk at a temperature of 10 ° C. and a concentration of 11.8% was added 3% of 10% trisodium citrate to calcium hydroxide.
Carbon dioxide gas was passed at a flow rate of 0 L / hr to produce calcium carbonate. Next, the calcium carbonate slurry was subjected to a pressure of 570 kg / c using a Doei Shoji M3 homogenizer.
BET specific surface area of an average particle diameter of 0.56μm was triturated with m ² 5
5 m ² / g of calcium carbonate slur was obtained. Table 1 shows the reaction conditions and results.

EXAMPLE 6 Trisodium citrate at a concentration of 10% was added to lime milk at a temperature of 10 ° C. and a concentration of 11.8%, and 1.0% with respect to calcium hydroxide.
1 kg / kg of calcium hydroxide
Carbon dioxide gas was passed at a flow rate of 700 L / hr to produce calcium carbonate. Next, 0.3% of phosphoric acid was added to the calcium carbonate slurry, and the slurry was pulverized at a pressure of 570 kg / cm ² with an M3 homogenizer of Doei Shoji to obtain an average particle diameter of 0.1 kg.
A calcium carbonate slur with a BET specific surface area of 54 μm and a surface area of 45 m ² / g was obtained. Table 1 shows the reaction conditions and results.

EXAMPLE 7 Carbon dioxide gas was passed through lime milk at a temperature of 10 ° C. and a concentration of 11.8% at a carbon dioxide gas flow rate of 1700 L / hr per 1 kg of calcium hydroxide. Trisodium citrate was added at 3% to calcium hydroxide.
Thereafter, calcium carbonate was produced at the same flow rate of carbon dioxide gas.
Next, the calcium carbonate slurry was heated to a temperature of 45 to 50.
The mixture was stirred at 180 ° C. for 2 days (180 rpm) to obtain a calcium carbonate slurr having an average particle size of 0.50 μm and a BET specific surface area of 34 m ² / g. Table 1 shows the reaction conditions and results.

Example 8 To a lime milk having a temperature of 10 ° C. and a concentration of 11.8% was added 3% of a 10% concentration of sodium tartrate to calcium hydroxide.
1700L / kg of calcium hydroxide is added to this slurry.
Carbon dioxide was passed through at a flow rate of hr of carbon dioxide to produce calcium carbonate. Next, the calcium carbonate slurry was stirred (180 rpm) at a temperature of 45 to 50 ° C. for 2 days to obtain a calcium carbonate slur with a BET specific surface area of 48 m ² / g having an average particle diameter of 0.42 μm. Table 1 shows the reaction conditions and results.

Example 9 To a lime milk having a temperature of 10 ° C. and a concentration of 11.8% was added 3% of sodium oxalate having a concentration of 10% to calcium hydroxide.
Carbon dioxide gas was passed at a flow rate of 0 L / hr to produce calcium carbonate. Next, this calcium carbonate slurry was stirred (180 rpm) at a temperature of 45 to 50 ° C. for 2 days to give a BET specific surface area of an average particle diameter of 0.44 μm of 49 m ² / g.
To obtain a calcium carbonate slur. Table 1 shows the reaction conditions and results.

Comparative Example 1 Carbon dioxide was passed through lime milk at a temperature of 10 ° C. and a concentration of 11.8% at a flow rate of 1700 L / hr of carbon dioxide per kg of calcium hydroxide to produce calcium carbonate. Next, this calcium carbonate slurry was stirred at a temperature of 45 to 50 ° C. for 2 days (1
80 rpm) to obtain a BE having an average particle size of 0.55 μm.
A calcium carbonate slur with a T specific surface area of 12 m ² / g was obtained. Table 1 shows the reaction conditions and results.

Comparative Example 2 Carbon dioxide gas was passed through lime milk at a temperature of 10 ° C. and a concentration of 11.8% at a carbon dioxide gas flow rate of 1700 L / hr per 1 kg of calcium hydroxide to produce calcium carbonate. Then, the calcium carbonate slurry was subjected to a pressure of 5 with an M3 homogenizer.
By pulverizing at 70 kg / cm ² , a calcium carbonate slur with an average particle size of 0.36 μm and a BET specific surface area of 10 m ² / g was obtained. Table 1 shows the reaction conditions and results.

[0027]

[Table 1]

Application Example 1 A fatty acid soda is added to calcium carbonate obtained in Examples 1 to 9 and Comparative Examples 1 and 2 to calcium carbonate in an amount of 7 to 1 to calcium carbonate.
After 0% surface treatment, the powder was dehydrated with a filter press and dried to obtain a powder of calcium carbonate. Using these powders, a vinyl chloride paste sol was prepared according to the following formulation, and its viscosity (viscosity at 2 rpm and 20 rpm) and thixotropy (TI value) were examined. Table 2 shows the results.

Formulation 1 Vinyl chloride paste resin (Nippon Zeon 121, manufactured by Nippon Zeon Co., Ltd.) 30 parts DOP 90 parts Calcium carbonate sample 30 parts

Formulation 2 Vinyl chloride paste resin (Nippon Zeon 121, manufactured by Nippon Zeon Co., Ltd.) 30 parts DOP 90 parts Calcium carbonate sample 60 parts

[0031]

[Table 2]

From the results shown in Table 2, the powders prepared from the calcium carbonates of Examples 1 to 9 are more finely dispersed than the conventional powders. High viscosity and thixotropy (T
I value), confirming that the dispersibility is extremely good.

[0033]

As described above, according to the present invention, calcium carbonate in which agglomerates of calcium carbonate are dispersed in the form of fine particles can be obtained, and a thickening agent for a paint, a sealing material, and a thixotropic agent for a vinyl chloride paste sol can be obtained. Property imparting agent, rubber reinforcing agent,
It is useful as a plastic reinforcing agent, an ultraviolet absorber in various fields, a pigment for coating coated paper, a pigment for printing ink, a carrier for agricultural chemicals, a toner for ink jet paper, a raw material for cosmetics, and the like.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C01F 11/18

Claims (9)

(57) [Claims] In producing calcium carbonate by blowing carbon dioxide gas into an aqueous suspension of calcium hydroxide, a substance which coordinates with metal ions to form a complex is added to the aqueous suspension of calcium hydroxide. A method for producing precipitated calcium carbonate, comprising producing calcium carbonate by a carbonation reaction and then aging the calcium carbonate. 2. The substance which forms a complex by coordinating to a metal ion is a hydroxycarboxylic acid, a polyhydroxycarboxylic acid, an aminopolycarboxylic acid, a polyphosphoric acid, an amino acid, an alkali metal salt or an alkaline earth metal salt thereof, The method according to claim 1, wherein the method is at least one selected from the group consisting of ammonium salts and ketones. 3. Hydroxycarboxylic acid is citric acid, oxalic acid or malic acid, polyhydroxycarboxylic acid is gluconic acid or tartaric acid, aminopolycarboxylic acid is iminodiacetic acid, ethylenediaminetetraacetic acid or nitrilotriacetic acid, polyphosphoric acid is hexametaphosphoric acid or tripolyacid. 3. The method according to claim 2, wherein the phosphoric acid and the amino acid are glutamic acid or aspartic acid, and the ketones are acetylacetone, methyl acetoacetate or allyl acetoacetate. 4. The method according to claim 1, wherein a substance forming a complex coordinated to the metal ion is added in an amount of 0.1 to 10% by weight based on calcium hydroxide. 5. The method according to claim 1, wherein a phosphorus-containing substance is added to the generated calcium carbonate slurry and the mixture is aged. 6. The method according to claim 5, wherein the phosphorus-containing substance is added in an amount of 0.01 to 0.6% by weight based on calcium carbonate. 7. The phosphorus-containing substance is at least one selected from the group consisting of phosphoric acid, phosphorous acid, phosphonic acid and derivatives thereof, alkali metal salts, alkaline earth metal salts and ammonium salts thereof. 6. The production method according to 6. 8. The carbonation reaction is carried out at a calcium hydroxide aqueous suspension concentration of 3.5 to 19.3% and a reaction initiation temperature of 8 to 30.
° C and carbon dioxide gas flow rate of 4 kg / kg of calcium hydroxide
The production method according to claim 1, wherein the production is performed under a condition of 0 to 1800 L / hr. 9. The method according to claim 1, wherein the aging is performed at a temperature of 20 to 70 ° C. by wet pulverization, ultrasonic dispersion or stirring.