JPS59217621A - Production of cubic calcium carbonate having 0.1[1.0mum average particle diameter and good dispersibility - Google Patents

Abstract

PURPOSE:To obtain the titled uniform calcium carbonate without secondary aggregation, by adding calcium hydroxide to an aqueous suspension of ultrafine cubic calcium carbonate, and introducing a gas containing gaseous carbon dioxide thereto. CONSTITUTION:A gas containing gaseous carbon dioxide is introduced into an aqueous suspension of calcium hydroxide to give an aqueous suspension of ultrafine cubic calcium carbonate having <0.1mum average particle diameter, and calcium hydroxide is then added and mixed with the resultant aqueous suspension. A gas containing gaseous carbon dioxide is then introduced thereinto to carbonate the calcium carbonate. Thus, calcium carbonate is produced and grown on ultrafine cubic calcium carbonate having <0.1mum average particle diameter as crystal nuclei to give the aimed uniform cubic calcium carbonate having 0.1-1.0mum average particle diameter. The desired cubic calcium carbonate having 0.1-1.0mum average particle diameter can be produced freely by repeating operations once or more times, adding calcium hydroxide and carbonating the produced and grown calcium carbonate as new crystal nuclei in the method.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. The present invention has an average particle diameter of 0. I) Generate and grow new calcium carbonate crystals on the crystal surface of ultrafine cubic calcium carbonate with a diameter of less than 1 m, and increase the average particle size to 0.1 to 1.
．． 0) The method on the right for producing 1 m of cubic calcium carbonate with good dispersibility.

Currently, the industrial method for producing precipitated calcium carbonate is to add 5 to 20% by weight aqueous suspension of calcium hydroxide,
Carbonation is carried out by introducing a gas containing 20 to 35% by volume of carbon dioxide (there is a carbonation method). In this manufacturing method,
Ultrafine cubic calcium carbonate with an average particle diameter of less than 1 mm, or spindle-shaped or needle-shaped calcium carbonate with an average particle diameter of 1 mm or more! has been manufactured. However, the average particle size is between 0.1 and +,
It has been considered difficult to produce calcium carbonate with a uniform particle size and shape of Jm by carbonation.

The inventor has determined that the average particle size is 0. After adding and mixing calcium hydroxide to an aqueous suspension of ultrafine cubic calcium carbonate with an average particle size of less than 0.1 μm, carbonation is performed by introducing a gas containing carbon dioxide gas to form ultrafine cubes with an average particle size of less than 0.1 μm. It is possible to produce uniform cubic calcium carbonate with an average particle size of 0.1 to 1.0 x m by cutting calcium carbonate into crystals and growing calcium carbonate on these crystal nuclei. , discovered what could be done and arrived at the present invention.

By using the calcium carbonate produced and grown in this method as a new crystal nucleus, adding calcium hydroxide, and carbonating it, repeating the operation one or more times, calcium carbonate crystals are successively grown, and the average particle diameter is 0.1～
It is possible to freely produce cubic calcium carbonate with a desired particle size of +, o, or um. The resulting calcium carbonate product has little secondary aggregation and provides excellent dispersibility, mechanical properties, and optical properties in rubber, plastics, paints, paper, and many other fields.

In this production method, the average particle diameter of the crystal nucleus particles is 0.
In the production reaction of extremely fine cubic calcium carbonate of less than 1 pm, the carbonation rate is fast when introducing a gas containing carbon dioxide into an aqueous suspension of calcium hydroxide. Many asymmetric crystal lattices occur in crystals. The existence of this irregular crystal lattice increases the crystal surface energy and activates the crystal surface of calcium carbonate. Therefore, when calcium hydroxide is added and carbonated, new calcium carbonate crystals are generated on the surface of the crystal nucleus. Growth does not occur, and the crystal nucleus particles aggregate together, resulting in 1
) Generate spindle-shaped or needle-shaped particles of 1 m or more.

However, if these crystal nuclei with high surface activity are left in a water suspension at room temperature for more than 2 weeks, the particles with high activity (i.e., particles with small particle size) will gradually dissolve in water and the activity will decrease. It is deposited on the surface of small particles, that is, particles with a large particle size, and crystal growth progresses gradually.

Crystals grown in this way have fewer irregular crystal lattices,
That is, the particles have a small surface activity 2, and at the same time, the size of the particles is made uniform, making them more preferable as crystal nucleus particles. This average particle skin with small surface activity + pm
ultrafine cubic calcium carbonate water) concentration of suspension of less than 0
．． The concentration of calcium hydroxide to be added is 1 to 10% by weight, preferably 2 to 5% by weight, and the concentration of calcium hydroxide to be added is 0.01 to 1.0 mol per 1 m0 of calcium carbonate, preferably 0.03 to 1.0 mol.
Add and mix to make 0.3 mOl, keep the temperature of the aqueous suspension at 5 to 706C, preferably 40 to 60C, and after thorough investigation, reduce the concentration to 1 to 10% by volume, preferably 2 to 5% by volume. % of carbon dioxide gas containing gas with a carbonation rate of 2 mol/m @mi
n or less, preferably at a rate of 0.5 to 1 mol 7m-mln.

Carbon dioxide-containing gases include limestone firing exhaust gas with a carbon dioxide concentration of 15% by volume or less, which was previously discarded, ultrafine cubic calcium carbonate with an average particle size of less than 0.1 μm, or spindle-shaped calcium carbonate with an average particle size of +, um or more. The carbonated exhaust gas from producing acicular calcium carbonate can be diluted with an inert gas such as air or nitrogen gas, which helps conserve resources. In the present invention, it is necessary to uniformize the formation and growth of crystal nucleus particles, and for this purpose, during carbonation, a calcium hydroxide aqueous suspension containing carbon dioxide gas and crystal nucleus particles is prepared at high speed. Increase the opportunity for contact with the calcium hydroxide aqueous suspension containing crystal nuclei by increasing the chance of contact with the calcium hydroxide aqueous suspension containing crystal nuclei by making the gas envelope diameter of the carbon dioxide gas smaller, or both of these. Either of these methods must be used at the same time.

If the growth of crystal nucleus particles is carbonated at a carbonation rate exceeding 2 mol/m-ml, the newly formed calcium carbonate will have a large number of irregular crystal lattices, that is, it will have a high surface activity. Q. The growth of calsila crystal nucleus particles should be carried out at a carbonation rate of 2 mol/m3·min or less.

The grown crystal nucleus particles have less asymmetric crystal lattice, that is, have less surface activity. Add and mix calcium hydroxide to this mixture and carbonate at a carbonation rate of 2m.
Even if it is repeated at a speed of 017 mth min or less, calcium carbonate crystal growth occurs only on the surface of the crystal nucleus, and crystals with many secondary aggregations, spindle shapes, and needle shapes do not occur, and the growth occurs in multiple stages. Even if the crystal nucleus particles are grown, the crystals will continue to grow in the original shape of the crystal nucleus particles. By controlling the number of repetitions of this carbonation, the average particle size is 0.1 to 1.0.
) A desired particle size of 1 m cubic calcium carbonate can be freely produced. This product has the advantage of not causing secondary aggregation even if it is dehydrated, dried, and powdered as it is.

When adding calcium hydroxide to an aqueous suspension of ultrafine cubic calcium carbonate with an average particle size of less than 0.1 μm, the temperature a should be set at 5 to 700. If the temperature exceeds 70C, carbon dioxide The effective utilization rate decreases, and if it is below 206C, the dissolution of calcium hydroxide in water will be small, making it difficult for calcium carbonate crystals to grow, and forming calcium carbonate crystals on the surface of calcium hydroxide crystals, which is undesirable. .

At a liquid temperature of 40 to 60@C, no new calcium carbonate crystals are formed, and all calcium hydroxide is used for calcium carbonate crystal growth.

If carbonation is performed under conditions other than the above, the average particle size will be 0.1
Cubic calcium carbonate of ~1.031 m with good dispersibility is not produced, but secondary aggregates, spindle-shaped, or needle-shaped with poor dispersibility are produced.

For example, 0, 1 p I'l1 which becomes a crystal, a core particle
If ultra-fine cubic calcium carbonate is used immediately after production, or if the concentration of crystal nucleus particles exceeds 10ii mass%, or if the concentration of calcium hydroxide, which is a growth agent for crystal nucleus particles, is If the concentration of carbonic acid exceeds 10% by volume, or if the carbonation rate exceeds 1 m01 per mol, or if the carbonation rate exceeds 2 mol/m"・min
When the temperature is exceeded, the calcium carbonate produced does not grow individually around the crystal nucleus, but either precipitates independently, or the precipitated particles aggregate together, forming aggregates with poor dispersibility, spindle shapes, or needles. When the shape is θ, it is impossible to obtain cubic calcium carbonate with good dispersibility and an average particle diameter of 0°1 to 1.0)Jm, which is the object of the present invention.

Examples will be shown below in order to make the features of the present invention more clear.

Example 3 Calcium hydroxide aqueous suspension 10% by weight, liquid temperature 20
25% by volume carbon dioxide diluted with air at 80°C.
It was introduced at 7m1d. I) When H8.5 was reached, the introduction of carbonate gas-containing gas was stopped, and ultrafine cubic calcium carbonate with an average particle diameter of o and o4 μm and a specific surface area (BET method) of aqm/g was obtained.

This ultrafine cubic calcium carbonate aqueous suspension is
When left to ripen for 5 days, ultrafine cubic calcium carbonate with an average particle size of 0.06 m/month and a specific surface area of 26 m/g was obtained.

This is used as a crystal nucleus, and this crystal nucleus aqueous suspension 10! Add a suspension of 30 g of calcium hydroxide in water, mix thoroughly,
The temperature of the aqueous suspension was set to C, and a gas containing 5% by volume of carbon dioxide diluted with air was introduced at 2RZm1n, and IIHlo
The introduction of carbon dioxide-containing gas was stopped.

This was regarded as the first crystal nucleus particle growth reaction, and the same operation was repeated thereafter. Calcium hydroxide a is added to the crystal nucleus water suspension.
x (9 + n ) g (n - number of crystal nucleus particle growth reactions, n = 2 or more) of water suspension 11 was added and thoroughly mixed, the temperature of the water suspension was set to 5060, and then diluted with air. 5% by volume of carbon dioxide gas containing 2.2×nβ/min
The introduction of carbon dioxide-containing gas was stopped at pH 10 to 9+5.

This crystal nucleus particle growth reaction was repeated 20 times,
The pH for stopping the reaction was set to 8.5. This material is dehydrated, dried, and crushed in the usual manner to produce flat lilies with a cryodiameter of 0.
．． 800 g of cubic calcium carbonate with a specific surface of 41 B+m/g and a specific surface of 41 B+m/g were obtained.

[Brief explanation of the drawing]

Figure 1 shows the number of crystal nucleus growth reactions and the specific surface area of the produced calcium carbonate according to Examples (BET Figure 1 0 5 10 15 20 Growth reaction number procedure correction...) Showa Jun 30, 1980 July 1982 1 day submission to the Commissioner of the Japan Patent Office 1. Indication of the case Showa 058 Patent No. 89871 2. Name of the invention 1. Method for producing cubic calcium carbonate with a size of 0.1 to 1.0 λm and good dispersibility 3 , amend ':Li' 43 patents related to t'i:j'j people and dogs'! - Saikumi City Shiu-'' No. 11, No. 26, No. 4, Date of amendment order 6, Contents of the amendment As shown in the attached sheet, the full text of ``Leg circumference for 1 requirement'' in Details of amendment 8 is corrected 2 , Claim 1 Calcium carbonate obtained by adding calcium hydroxide to an aqueous suspension of ultrafine cubic calcium carbonate with an average nucleon diameter of less than O,+,U°m, and adding carbon dioxide-containing gas to the aqueous suspension. Production method. 2 Average particle size 0.1. 2. The manufacturing method according to claim 1, wherein 1 d of ultrafine cubic calcium carbonate water suspension of um Miura is left at room temperature for two weeks or more to form jj144. 3 Average particle diameter o, +, um as described in claim 2
Claim 1: Calcium hydroxide is added to an aqueous suspension of ultrafine cubic calcium carbonate in the form of powder or aqueous suspension, and carbonation is carried out by introducing a gas containing carbon dioxide gas
Manufacturing method described in section. 4.0 as stated in claim 3. +7ud ultrafine cubic calcium carbonate water suspension/@Liquid concentration 0.1-1
The manufacturing method according to claim 1, wherein the concentration is 0%. 4 of calcium hydroxide according to claim 83
The degree of charcoal modified calcium is QC1, O+ ~1. O
4. The method of claim 1, which is m o l. 6. The method for producing a single-temperature product according to claim 1, wherein the calcium carbonate-containing calcium hydroxide suspension according to claim 3 is heated at a temperature of 5 to 70°C. 7 Patent 8tlt Required 1. The method for producing fA according to claim 1, in which the carbon dioxide-containing gas according to claim 3 has a content of 1 to 10% by volume. 8 patent claim 1: f 匝IFI 4th quotation: The conversion speed of the charcoal is adjusted to 2 m o by adjusting the speed of carbon dioxide-containing gas.
l/rn”・min [mol: molda of calcium hydroxide, m: 1u meter of water suspension volume, mi
n: 14 minutes (C minutes)) A method for producing Shigeru according to claim 1, which is carried out as follows. 9. The feature of stopping the introduction of the carbon dioxide-containing gas according to claim 3 at reaction stage 1[)H9-12. 'F61
The manufacturing method according to item 1 of the scope of claim. , cO The manufacturing method according to claim 1, wherein the method according to claim 3 is repeated one or more times. 11. The manufacturing method according to claim 1, wherein the introduction of the carbon dioxide-containing gas according to claim 10 is stopped at a pH of 7 to 9.

Claims (1)

[Claims] 1. Addition of calcium hydroxide to an ultrafine cube-shaped calcium carbonate aqueous suspension with an average particle diameter of less than 0.1 μm obtained by introducing a carbon dioxide gas-containing gas into an aqueous suspension of calcium hydroxide. A method for producing well-dispersible cubic calcium carbonate having an average particle diameter of 0.1 to 1.0) 1 m and obtained by adding carbon dioxide gas and introducing a carbon dioxide-containing gas. Lucium dihydroxide aqueous suspension concentration: 5 to 15% by weight A temperature: 25°C or less, carbon dioxide gas concentration: 20 to 35% by volume
2. The manufacturing method according to claim 1, which is obtained by introducing a carbon dioxide-containing gas and stopping the introduction of a carbon dioxide-containing gas when IIH of the reaction system is 7 to 9. 3Average diameter of the axle: 0. The manufacturing method according to claim 1, wherein an aqueous suspension of extremely fine cubic calcium carbonate having a particle diameter of less than Ipm is left to mature at room temperature for two weeks or more. 4 Average particle diameter as stated in claim 3: 0, 1
Claim 1: Calcium hydroxide is added to an aqueous suspension of ultrafine cubic calcium carbonate with a particle diameter of less than pm by a powder or aqueous suspension method, and carbonation is carried out by introducing a gas containing carbon dioxide gas. Manufacturing method described in section. 5. Ultrafine cubic calcium carbonate aqueous suspension of less than 0.1 JJm as described in Claim 4, wherein the concentration of a is 0.1 to 0.1 JJm.
The manufacturing method according to claim 1, wherein the amount is 10% by weight. 6 The concentration of calcium hydroxide according to claim 4 is 0.01 to 1.0 m01 per 1 m01 of calcium carbonate.
A manufacturing method according to claim 1. 7. The manufacturing method according to claim 1, wherein the calcium carbonate-containing calcium hydroxide aqueous suspension according to claim 4 is heated at a temperature of 5 to 70°C. 8. The manufacturing method according to claim 1, wherein the concentration of the carbon dioxide-containing gas according to claim 4 is 1 to 10% by volume. 9. Carbonation rate-sensitive carbonate scum-containing gas according to claim 4 can be introduced at a rate of 2 mol/m'amin.
(mol: number of moles of potassium hydroxide, m: 1 cubic meter of water suspension amount, min: hourly opening (minutes)) or less. . 10. The manufacturing method as set forth in claim 1, wherein the introduction of the carbonate-containing gas as set forth in claim 4 is stopped at a pH of 9 to 12 of the reaction solution. 11. The mold making method according to claim 1, which comprises repeating the method according to claim 4 one time more times. 12. The manufacturing method according to claim 1, in which the introduction of the carbonic acid-containing gas according to claim 11 is stopped at a pH of 7 to 9 of the reaction solution;