CA2196124C - Process for preparing colloidal calcium carbonate by particle size - Google Patents
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- CA2196124C CA2196124C CA002196124A CA2196124A CA2196124C CA 2196124 C CA2196124 C CA 2196124C CA 002196124 A CA002196124 A CA 002196124A CA 2196124 A CA2196124 A CA 2196124A CA 2196124 C CA2196124 C CA 2196124C
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- calcium carbonate
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/18—Carbonates
- C01F11/184—Preparation of calcium carbonate by carbonation of solutions based on non-aqueous solvents
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/18—Carbonates
- C01F11/181—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/18—Carbonates
- C01F11/182—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by an additive other than CaCO3-seeds
- C01F11/183—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by an additive other than CaCO3-seeds the additive being an organic compound
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/02—Compounds of alkaline earth metals or magnesium
- C09C1/021—Calcium carbonates
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
- C09C3/08—Treatment with low-molecular-weight non-polymer organic compounds
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/30—Particle morphology extending in three dimensions
- C01P2004/38—Particle morphology extending in three dimensions cube-like
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
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- Geology (AREA)
- Inorganic Chemistry (AREA)
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- General Health & Medical Sciences (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention provides a process for the preparation of a colloidal calcium carbonate of which the particles have a specific size in the range of more than 0.04 µm to less than 0.08 µm, which has little affinity of aggregation and has properties suitable for specific uses. First, after adding an additive, for example, sugar to increase a concentration of calcium ion, to an aqueous lime suspension, by introducing a gas containing carbon dioxide thereinto, a colloidal calcium carbonate of 0.04 µm in particle size is obtained. And then by adding a hydroxide with univalent or bivalent cation to the above aqueous suspension and agitating it at the rate of 100 to 5,000 as Reynolds number while the temperature thereof is heated up to 40 to 95 °C, a desired colloidal calcium carbonate of which particle size is increased by + 0.005 µm, i.e., 0.045, 0.050 to 0.075 µm through the ripening of particle is obtained.
Description
PROCESS FOR PREPARING COLLOIDAL CALCIUM
CARBONATE BY PARTICLE SIZE
This invention relates to a process for preparing cubic crystals of s colloidal calcium carbonate, and more particularly for preparing colloidal calcium carbonates of specific particle size in the range of greater than 0.04 ~.m to less than 0.08 ~,m.
Throughout the specification and appended claims, the term "size" of calcium carbonate crystals refers to the length of one edge of the cubic io crystal.
Calcium carbonate powders less than 0.1 pm are demanded as a functional filler in various fields of industry such as rubber, plastics, paint, ink and sealant. Colloidal calcium carbonate powders of 0.04 p,m and 0.08 ~m have been heretofore mainly used, however, there is a need for more is subdivided particle sizes in the range of greater than 0.04 ~m to less than 0.08 wm, i.e., 0.045 pm to 0.075 Vim, depending on the needs of each industry.
The finer than 0.1 p,m the size of colloidal calcium carbonate powders is, the more improved such properties as strength, fluidity and the like are, 2o and vice versa the more strong an aggregation property is. Therefore, when calcium carbonate powders are admixed with matrix or vehicle, the minimum particle size of powders uniformly dispersed by shearing force becomes the most suitable particle size for a specific industry. On the basis of the above fact, there is a necessity for more subdivided particles in the range of greater Zs than 0.04 p,m to less than 0.08 Vim.
According to a conventional process, colloidal calcium carbonate is usually produced by introducing a carbon dioxide-containing gas having a concentration of 20 to 40 % by volume of carbon dioxide at a rate of 40 to 100 liters/min. into an aqueous suspension of calcium hydroxide having a 3o concentration of 3 to 10 % by weight of calcium hydroxide and being kept at a temperature of 10 to 20 °C, to yield a cubic calcium carbonate of 0.04 pm in particle size.
The aqueous suspension containing the cubic calcium carbonate of 0.04 ~m in particle size as obtained above is heated up to a temperature of 40 to 80 °C, and then ripened without agitation for 4 to 5 days to yield a cubic calcium carbonate of 0.08 ~m in particle size. At that time, the pH of the suspension rises from 6.8 t 0.2 to about 11.5, however, if any agitation, even s a little, is performed, the process of ripening can not progress.
When the pH thereof becomes stable at about 11.5, some supernatant is separated therefrom leaving a suspension of 10 to 20 % concentration which is then neutralized by introducing a carbon dioxide-containing gas thereinto.
io By adding an alkali metal solution consisting of a fatty acid or a resin acid, as a surface treatment, to the suspension containing the colloidal calcium carbonate of 0.08 ~m in particle size as obtained above, powders of colloidal calcium carbonate are produced after dehydrating through a filter press, drying and pulverizing.
is However, it takes a long time to ripen the aqueous suspension, for example, five days for the colloidal calcium carbonate of 0.08 ~m in particle size. During the period from the first to the fourth days, the particles are not uniform and will vary from 0.04 to 0.08 ~m in size, and thus the colloidal calcium carbonates can not be used for their intended use.
2o U. S. Patent. No. 4,124,688 (Shibazaki et al.) describes an invention whereby cubic calcium carbonate crystals of uniform size are prepared by contacting with C02 a starting aqueous suspension containing Ca(OH)2 and cubic CaC03 crystals less than 0.1 ~,m in size, and then adding Ca(OH)2 to the suspension resulting from the first step, and finally contacting the resultant 2s mixture with C02.
U. S. Patent No. 4,133,894 (Shibazaki et al.) describes an invention that precipitated calcium carbonate of uniform particle size is produced by contacting a suspension of calcium hydroxide with a carbon dioxide-containing gas in three steps. The particle size of precipitated calcium 3o carbonate can be optionally selected by suitably adjusting reaction conditions.
U. S. Patent No. 5,075,093 (Tanaka et al.) describes a two-step carbonation method of milk of lime in which partially carbonated milk of lime is admixed with an aqueous carbonating solution containing an alkali metal carbonate or ammonium carbonate and an alkali metal hydroxide or ammonium hydroxide to complete the carbonation of calcium hydroxide.
Particles having platelet-like configuration of a thickness in the range of oil 0.1 to 0.3 pm and dimension within the plane of the platelet from 0.5 to 2 ~m are s prepared.
U. S. Patent No. 5,332,564 (Chapnerkar et al.) describes a process for producing rhombic or barrel shaped precipitated calcium carbonate. Quicklime is slaked in an aqueous solution containing about 0.1 % to about 2 % by weight of a sugar, based upon the weight of CaC03 to be produced. Carbon io dioxide is added to the slaked lime slurry at a preferred temperature of about 50 "F-70 "F, until, the pH drops from about 11-12 to about 7-8.
None of the above patents addresses the production of colloidal calcium carbonate having a specific uniform particle size depending on its intended use.
is The present invention is directed towards the provision of a process for producing uniform particles of colloidal calcium carbonate by particle size in the range of more than 0.04 pm to less than 0.08 Vim.
The present invention also is directed towards the provision of a process for rapidly ripening an aqueous suspension containing the colloidal 2o calcium carbonate having respective particle size of 0.04 wm in particle size to yield colloidal calcium carbonates having respective particle size of 0.045, 0.050, 0.055, 0.060, 0.065, 0.070 and 0.075 Vim, as increased by 0.005 pm in particle size (as measured by electron microscopy analysis).
The present invention further is directed towards the provision of a 2s process for producing powders of colloidal calcium carbonate of which particle sizes are uniform and aggregation property is low.
In accordance with the present invention, there is provided a process for preparing cubic particles of colloidal calcium carbonate having an average size in the range of 0.045 ~.m to 0.075 Vim, by a step size of 0.005 Vim, which 3o process comprises the steps of: (a) adding sugar or a chelating agent into an aqueous suspension of calcium hydroxide having a concentration of 3 to 8% by weight and a temperature of 14 °C to 18 °C, the amount of said sugar or said chelating agent added being 0.2 to 3.0 parts by weight per 100 parts by weight of calcium hydroxide contained in the aqueous suspension; (b) introducing a gas containing 20 to 40% by volume of carbon dioxide into the aqueous suspension from step (a) at a rate of 40 to 200 liters per minute per kg of calcium hydroxide as the starting material to produce calcium carbonate s particles having an average size of 0.04 pm when the pH of the suspension reaches 6.8; (c) adding a hydroxide with a univalent or bivalent cation into the aqueous suspension from step (b) at an amount of 0.1 to 0.8 parts by weight per 100 parts by weight of calcium hydroxide as the starting material to neutralize the remaining carbonate ions therein; (d) heating the aqueous io suspension from step (c) up to a temperature of 40 °C to 95 °C and simultaneously agitating at a Reynolds number of 100 to 5,000, whereby the pH of said aqueous suspension is raised to a desirable value; and (e) introducing the same carbon dioxide-containing gas as used in step (b) into the aqueous suspension from step (d) to neutralize it.
is Features indispensable for the constitution of the present invention are described as follows, which can be distinguished from the existing processes.
A first constitutional feature of the present invention is to add 0.2 to 3.0 parts by weight (to be hereinafter referred to briefly as "part") of sugar or a chelating agent, such as EDTA (ethylenediaminetetraacetic acid) per 100 2o parts of Ca(OH)2 included in an aqueous suspension to the aqueous suspension in order to increase the concentration of calcium ion in the suspension. Then, the colloidal calcium carbonate of 0.04 p,m in particle size is yielded by introducing a carbon dioxide-containing gas thereinto. If the amount added is below 0.2 part, there may be no effect of accelerating the 2s ripening step, and if it is above 3.0 parts the ripened particles may not become uniform.
A second constitutional feature of the present invention is to add 0.1 to 0.8 part of a hydroxide with an univalent or bivalent cation per 100 parts of Ca(OH)2to the aqueous suspension at the beginning of ripening. The 3o hydroxides with univalent cation include NaOH, KOH and so on, and those with bivalent cation include Ca(OH)2, Mg(OH)2, Zn(OH)2 and so on. If the amount of the hydroxide added is below 0. 1 part, the addition may have no effect, and if it is above 0.8 part, the size distribution of the produced particles may not be uniform. Generally, the size of desired particle is in inverse proportion to a BET surface area, and the pH of the aqueous suspension is increased up to about 11.5. However, the exact value may change depending on the kind and amount of the hydroxide. Therefore, such parameters can be s determined by the relation between the reaction time and the particle size in the real condition of production third constitutional feature of the present invention is to ripen the aqueous suspension containing the colloidal calcium carbonate of 0.04 ~m in particle size by raising the temperature to 40 to 95 ~C
and agitating at a Reynolds number (Re) of 100 to 5,000 to obtain uniform io particle growth. The Reynolds number can be obtained by the following formula (1 ). If the agitating speed is under 100 as Reynolds number, the ripening rate may be very low, and if it is above 5,000, the produced particle may not be uniform.
1 s Re= ~4nD2 ( 1 ) Wherein Re Reynolds number p density of solution 2o n revolution number of blade (r.p.s) D diameter of blade (cm) ft viscosity of solution (poise) A fourth constitutional feature of the present invention is to concentrate 2s the aqueous suspension containing the colloidal calcium carbonate in the range of from greater than 0.04 ~m to less than 0.08 ~,m in particle size to a concentration of 14 ~ 1 % by weight of colloidal calcium carbonate, and then to treat surfaces thereof with such a surface treatment as fatty acid, resin acid or the like. By dehydrating, drying and pulverizing the resulting product, powders 30 of colloidal calcium carbonate having uniform particle size and low aggregation property are obtained. According to the processes mentioned above, one can obtain novel colloidal calcium carbonate by particle size depending on its intended use.
CARBONATE BY PARTICLE SIZE
This invention relates to a process for preparing cubic crystals of s colloidal calcium carbonate, and more particularly for preparing colloidal calcium carbonates of specific particle size in the range of greater than 0.04 ~.m to less than 0.08 ~,m.
Throughout the specification and appended claims, the term "size" of calcium carbonate crystals refers to the length of one edge of the cubic io crystal.
Calcium carbonate powders less than 0.1 pm are demanded as a functional filler in various fields of industry such as rubber, plastics, paint, ink and sealant. Colloidal calcium carbonate powders of 0.04 p,m and 0.08 ~m have been heretofore mainly used, however, there is a need for more is subdivided particle sizes in the range of greater than 0.04 ~m to less than 0.08 wm, i.e., 0.045 pm to 0.075 Vim, depending on the needs of each industry.
The finer than 0.1 p,m the size of colloidal calcium carbonate powders is, the more improved such properties as strength, fluidity and the like are, 2o and vice versa the more strong an aggregation property is. Therefore, when calcium carbonate powders are admixed with matrix or vehicle, the minimum particle size of powders uniformly dispersed by shearing force becomes the most suitable particle size for a specific industry. On the basis of the above fact, there is a necessity for more subdivided particles in the range of greater Zs than 0.04 p,m to less than 0.08 Vim.
According to a conventional process, colloidal calcium carbonate is usually produced by introducing a carbon dioxide-containing gas having a concentration of 20 to 40 % by volume of carbon dioxide at a rate of 40 to 100 liters/min. into an aqueous suspension of calcium hydroxide having a 3o concentration of 3 to 10 % by weight of calcium hydroxide and being kept at a temperature of 10 to 20 °C, to yield a cubic calcium carbonate of 0.04 pm in particle size.
The aqueous suspension containing the cubic calcium carbonate of 0.04 ~m in particle size as obtained above is heated up to a temperature of 40 to 80 °C, and then ripened without agitation for 4 to 5 days to yield a cubic calcium carbonate of 0.08 ~m in particle size. At that time, the pH of the suspension rises from 6.8 t 0.2 to about 11.5, however, if any agitation, even s a little, is performed, the process of ripening can not progress.
When the pH thereof becomes stable at about 11.5, some supernatant is separated therefrom leaving a suspension of 10 to 20 % concentration which is then neutralized by introducing a carbon dioxide-containing gas thereinto.
io By adding an alkali metal solution consisting of a fatty acid or a resin acid, as a surface treatment, to the suspension containing the colloidal calcium carbonate of 0.08 ~m in particle size as obtained above, powders of colloidal calcium carbonate are produced after dehydrating through a filter press, drying and pulverizing.
is However, it takes a long time to ripen the aqueous suspension, for example, five days for the colloidal calcium carbonate of 0.08 ~m in particle size. During the period from the first to the fourth days, the particles are not uniform and will vary from 0.04 to 0.08 ~m in size, and thus the colloidal calcium carbonates can not be used for their intended use.
2o U. S. Patent. No. 4,124,688 (Shibazaki et al.) describes an invention whereby cubic calcium carbonate crystals of uniform size are prepared by contacting with C02 a starting aqueous suspension containing Ca(OH)2 and cubic CaC03 crystals less than 0.1 ~,m in size, and then adding Ca(OH)2 to the suspension resulting from the first step, and finally contacting the resultant 2s mixture with C02.
U. S. Patent No. 4,133,894 (Shibazaki et al.) describes an invention that precipitated calcium carbonate of uniform particle size is produced by contacting a suspension of calcium hydroxide with a carbon dioxide-containing gas in three steps. The particle size of precipitated calcium 3o carbonate can be optionally selected by suitably adjusting reaction conditions.
U. S. Patent No. 5,075,093 (Tanaka et al.) describes a two-step carbonation method of milk of lime in which partially carbonated milk of lime is admixed with an aqueous carbonating solution containing an alkali metal carbonate or ammonium carbonate and an alkali metal hydroxide or ammonium hydroxide to complete the carbonation of calcium hydroxide.
Particles having platelet-like configuration of a thickness in the range of oil 0.1 to 0.3 pm and dimension within the plane of the platelet from 0.5 to 2 ~m are s prepared.
U. S. Patent No. 5,332,564 (Chapnerkar et al.) describes a process for producing rhombic or barrel shaped precipitated calcium carbonate. Quicklime is slaked in an aqueous solution containing about 0.1 % to about 2 % by weight of a sugar, based upon the weight of CaC03 to be produced. Carbon io dioxide is added to the slaked lime slurry at a preferred temperature of about 50 "F-70 "F, until, the pH drops from about 11-12 to about 7-8.
None of the above patents addresses the production of colloidal calcium carbonate having a specific uniform particle size depending on its intended use.
is The present invention is directed towards the provision of a process for producing uniform particles of colloidal calcium carbonate by particle size in the range of more than 0.04 pm to less than 0.08 Vim.
The present invention also is directed towards the provision of a process for rapidly ripening an aqueous suspension containing the colloidal 2o calcium carbonate having respective particle size of 0.04 wm in particle size to yield colloidal calcium carbonates having respective particle size of 0.045, 0.050, 0.055, 0.060, 0.065, 0.070 and 0.075 Vim, as increased by 0.005 pm in particle size (as measured by electron microscopy analysis).
The present invention further is directed towards the provision of a 2s process for producing powders of colloidal calcium carbonate of which particle sizes are uniform and aggregation property is low.
In accordance with the present invention, there is provided a process for preparing cubic particles of colloidal calcium carbonate having an average size in the range of 0.045 ~.m to 0.075 Vim, by a step size of 0.005 Vim, which 3o process comprises the steps of: (a) adding sugar or a chelating agent into an aqueous suspension of calcium hydroxide having a concentration of 3 to 8% by weight and a temperature of 14 °C to 18 °C, the amount of said sugar or said chelating agent added being 0.2 to 3.0 parts by weight per 100 parts by weight of calcium hydroxide contained in the aqueous suspension; (b) introducing a gas containing 20 to 40% by volume of carbon dioxide into the aqueous suspension from step (a) at a rate of 40 to 200 liters per minute per kg of calcium hydroxide as the starting material to produce calcium carbonate s particles having an average size of 0.04 pm when the pH of the suspension reaches 6.8; (c) adding a hydroxide with a univalent or bivalent cation into the aqueous suspension from step (b) at an amount of 0.1 to 0.8 parts by weight per 100 parts by weight of calcium hydroxide as the starting material to neutralize the remaining carbonate ions therein; (d) heating the aqueous io suspension from step (c) up to a temperature of 40 °C to 95 °C and simultaneously agitating at a Reynolds number of 100 to 5,000, whereby the pH of said aqueous suspension is raised to a desirable value; and (e) introducing the same carbon dioxide-containing gas as used in step (b) into the aqueous suspension from step (d) to neutralize it.
is Features indispensable for the constitution of the present invention are described as follows, which can be distinguished from the existing processes.
A first constitutional feature of the present invention is to add 0.2 to 3.0 parts by weight (to be hereinafter referred to briefly as "part") of sugar or a chelating agent, such as EDTA (ethylenediaminetetraacetic acid) per 100 2o parts of Ca(OH)2 included in an aqueous suspension to the aqueous suspension in order to increase the concentration of calcium ion in the suspension. Then, the colloidal calcium carbonate of 0.04 p,m in particle size is yielded by introducing a carbon dioxide-containing gas thereinto. If the amount added is below 0.2 part, there may be no effect of accelerating the 2s ripening step, and if it is above 3.0 parts the ripened particles may not become uniform.
A second constitutional feature of the present invention is to add 0.1 to 0.8 part of a hydroxide with an univalent or bivalent cation per 100 parts of Ca(OH)2to the aqueous suspension at the beginning of ripening. The 3o hydroxides with univalent cation include NaOH, KOH and so on, and those with bivalent cation include Ca(OH)2, Mg(OH)2, Zn(OH)2 and so on. If the amount of the hydroxide added is below 0. 1 part, the addition may have no effect, and if it is above 0.8 part, the size distribution of the produced particles may not be uniform. Generally, the size of desired particle is in inverse proportion to a BET surface area, and the pH of the aqueous suspension is increased up to about 11.5. However, the exact value may change depending on the kind and amount of the hydroxide. Therefore, such parameters can be s determined by the relation between the reaction time and the particle size in the real condition of production third constitutional feature of the present invention is to ripen the aqueous suspension containing the colloidal calcium carbonate of 0.04 ~m in particle size by raising the temperature to 40 to 95 ~C
and agitating at a Reynolds number (Re) of 100 to 5,000 to obtain uniform io particle growth. The Reynolds number can be obtained by the following formula (1 ). If the agitating speed is under 100 as Reynolds number, the ripening rate may be very low, and if it is above 5,000, the produced particle may not be uniform.
1 s Re= ~4nD2 ( 1 ) Wherein Re Reynolds number p density of solution 2o n revolution number of blade (r.p.s) D diameter of blade (cm) ft viscosity of solution (poise) A fourth constitutional feature of the present invention is to concentrate 2s the aqueous suspension containing the colloidal calcium carbonate in the range of from greater than 0.04 ~m to less than 0.08 ~,m in particle size to a concentration of 14 ~ 1 % by weight of colloidal calcium carbonate, and then to treat surfaces thereof with such a surface treatment as fatty acid, resin acid or the like. By dehydrating, drying and pulverizing the resulting product, powders 30 of colloidal calcium carbonate having uniform particle size and low aggregation property are obtained. According to the processes mentioned above, one can obtain novel colloidal calcium carbonate by particle size depending on its intended use.
When summarizing the above content, according to the process of the present invention, after the addition of the material to increase the concentration of calcium ion to the aqueous lime suspension, the colloidal calcium carbonate of 0.04 ~m in particle size is obtained by introducing the s carbon dioxide-containing gas thereinto. Then, by adding the hydroxide with an univalent or bivalent cation to the resulting suspension, and agitating the suspension at a Reynolds number of 100 to 5,000 while the temperature is raised to 40 to 95 °C. Accordingly, the colloidal calcium carbonate of 0.04 ~m in particle size is ripened and the pH of aqueous suspension rises, as a result, io yielding colloidal calcium carbonates of which each length of one edge is increased by 0.005 Vim, i.e., cubic crystals of 0.045 to 0.075 ~,m, corresponding to the increased pH of the aqueous suspension.
Therein, the above mentioned "ripening" means the phenomenon that a hydrolysis reaction of the colloidal calcium carbonate of 0.04 ~m in particle is size occurs when its aqueous suspension becomes weakly basic with carbon dioxide gases released from the aqueous suspension neutralized shortly after the first reaction. Finer colloidal calcium carbonates are eluted into the aqueous suspension and then are recrystallized on the lattice defect of other relatively large particles. Consequently, the surface activity thereof is reduced 2o and stabilized, and thus the aggregation property thereof is reduced and simultaneously the particle thereof becomes larger.
The colloidal calcium carbonate having a specific particle size in the range of greater than 0.04 ~m to less than 0.08 ~m according to the process of the present invention is prepared by growing up the colloidal calcium 2s carbonate particle of 0.04 ~m in size.
The calcium carbonate powder as obtained above can be used as a good filler to improve the properties of product impregnated therewith and have a good dispersion property due to the stabilized surface activity, the reduced aggregation property and the uniform size which seems to be caused 3o by the adding material and the agitating power.
The present invention will now be described in more detail by way of examples, comparative examples and reference examples. The examples are presented for the illustration purpose only and should not be interpreted in any restrictive way.
(Example 1 ) s After a 10% aqueous solution of sugar was added to an aqueous lime suspension of a concentration of 5% by weight of calcium hydroxide and a temperature of 15 °C at an amount of 0.5 part per 100 parts of Ca(OH)2 a gas containing 30% by volume of carbon dioxide was then introduced thereinto.
When the pH of the resulting aqueous suspension became 6.8, an aqueous io suspension containing colloidal calcium carbonate particles of 0.04 pm in size was obtained. An aqueous solution of KOH having a concentration of 10% by weight was added to the resultant aqueous suspension at an amount of 0.6 part per 100 parts of Ca(OH)2 as the starting material. The aqueous suspension was heated to 80 °C, and simultaneously agitated at a Reynolds is number of 2,000. The carbon dioxide-containing gas was again introduced thereinto when the pH of the aqueous suspension became 8.2 after 2 hours' agitation. A precipitating agent was added thereto at an amount of 300 ppm, and then the supernatant was separated from the aqueous suspension, so that an aqueous suspension containing colloidal calcium carbonate particles 20 of 0.05 ~.m in size at a concentration of 15% by weight was obtained. In a . mixer, particle surfaces of colloidal calcium carbonate were treated by adding a 10% solution of sodium salt of fatty acid at an amount of 3 parts per 100 parts of CaC03 produced at a temperature of 90 °C. the suspension was concentrated through a filter press to a concentration of 55 % by weight of 2s solids, dried at a temperature of 80 °C, pulverized and classified to produce colloidal calcium carbonate powders of 0.05 ~m in particle size.
(Example 2) 3o Example 1 was repeated except that the time for ripening was 3 hours and the pH of the aqueous suspension was 9.5. The final product was powders of colloidal calcium carbonate having 0.06 ~,m particle size.
(Example 3) Example 1 was repeated except that the time for ripening was 4 hours and the pH of the aqueous suspension was 10.8. The final product was s powders of colloidal calcium carbonate having 0.07 pm particle size.
(Comparative Example 1 ) Example 1 was repeated except that the agitation of an aqueous to suspension was performed at a Reynolds number of 8,000. Powders of colloidal calcium carbonate, having 0.045 wm particle size, were obtained, however, the pH of a suspension after 2-hour-ripenning was 8.0 and the particle size of the product was not uniform.
is (Comparative Example 2) Example 1 was repeated except that the amount of KOH added was 2.0 part per 100 parts of Ca(OH)2. Powders of colloidal calcium carbonate, having 0.05 pm particle size, were obtained, however, the pH of a suspension ao after 2-hour-ripenning was 9.2 and the particle size of the product was not uniform.
(Reference Example 1 ) 2s According to a conventional process to carbonate an aqueous lime suspension, a gas containing 30 % by volume of carbon dioxide was added at a rate of 100 a per minute per kg of Ca(OH)2 to the aqueous lime suspension having a concentration of 5% by weight and a temperature of 15 "C.
Concentration, surface-treatment, dehydration, drying, pulverization and 3o classification were performed in the same manner as in Example 1 to give a powdery calcium carbonate product. The final product was powders of colloidal calcium carbonate having 0.04 ~,m particle size.
(Reference Example 2) The aqueous suspension carbonated by the process of Reference Example 1 was maintained and ripened for 100 hours while being heated to a s temperature of i i.,~~ ~~ ~,1~ i~_1 80 "C. Dehydration, dryring, pulverization and classification were performed in the same manner as in Reference Example 1 to give a powdery calcium carbonate product. The final product was powders of colloidal calcium carbonate having 0.08 ran particle size.
(Application Example) According to the formulation given below, each of calcium carbonate powders obtained in Examples 1 to 3, Comparative Examples 1 and 2 and Reference Examples 1 and 2 was added to DOP, a plasticizer of PVC paste resin, dispersed therein by a conventional method, kneaded by an automakic stirrer for 10 min., and measured with a method of Smm-thickness-slop and a grind gauge to know its grid.
'The measured results are listed in Table 1.
Formulation receipt Geon 1? l (polyvinylchloride paste resin) SOg DOP (dioctylphthalate) 60g Colloidal calcium carbonate SOg Table 1 Particle$ET Slope Grid Size(;.lm)Surface ''via ~ judge-~tm judge-Dispersity (m fig) merit merit Example 0.05 28 7 ~O 3 ~O (>
Example 0.06 25 1 UO 3 ~ O
Example 0.07 22 1 O~ 3 J
Comparativep 29 60 i~ 65 0,~5 Example .
Comparative0,05 27 70 n 70 =1. p Example Reference p.0~ 30 150 X 90 X X
Example Reference 0.08 20 80 X 60 ,~ X
Example Z
NOTE : The smaller the values of the slope and the grid are, the better their properties are ~: excellent ~: good !'~: average X : bad ,::~ ~, :~
It is evident from the above results that the process according to the present invention provides particles of colloidal calcium carbonate which show lower at~nity of aggregation, superior uniformity and dispersity in the end products.
These above examples are set forth to illustrate specifc embodiments of the invention and are not intended to limit the scope of the processes of the present invention. Additional embodiments and advantages within the scope of the claimed invention will be apparent to one of ordinary skill in the art.
Therein, the above mentioned "ripening" means the phenomenon that a hydrolysis reaction of the colloidal calcium carbonate of 0.04 ~m in particle is size occurs when its aqueous suspension becomes weakly basic with carbon dioxide gases released from the aqueous suspension neutralized shortly after the first reaction. Finer colloidal calcium carbonates are eluted into the aqueous suspension and then are recrystallized on the lattice defect of other relatively large particles. Consequently, the surface activity thereof is reduced 2o and stabilized, and thus the aggregation property thereof is reduced and simultaneously the particle thereof becomes larger.
The colloidal calcium carbonate having a specific particle size in the range of greater than 0.04 ~m to less than 0.08 ~m according to the process of the present invention is prepared by growing up the colloidal calcium 2s carbonate particle of 0.04 ~m in size.
The calcium carbonate powder as obtained above can be used as a good filler to improve the properties of product impregnated therewith and have a good dispersion property due to the stabilized surface activity, the reduced aggregation property and the uniform size which seems to be caused 3o by the adding material and the agitating power.
The present invention will now be described in more detail by way of examples, comparative examples and reference examples. The examples are presented for the illustration purpose only and should not be interpreted in any restrictive way.
(Example 1 ) s After a 10% aqueous solution of sugar was added to an aqueous lime suspension of a concentration of 5% by weight of calcium hydroxide and a temperature of 15 °C at an amount of 0.5 part per 100 parts of Ca(OH)2 a gas containing 30% by volume of carbon dioxide was then introduced thereinto.
When the pH of the resulting aqueous suspension became 6.8, an aqueous io suspension containing colloidal calcium carbonate particles of 0.04 pm in size was obtained. An aqueous solution of KOH having a concentration of 10% by weight was added to the resultant aqueous suspension at an amount of 0.6 part per 100 parts of Ca(OH)2 as the starting material. The aqueous suspension was heated to 80 °C, and simultaneously agitated at a Reynolds is number of 2,000. The carbon dioxide-containing gas was again introduced thereinto when the pH of the aqueous suspension became 8.2 after 2 hours' agitation. A precipitating agent was added thereto at an amount of 300 ppm, and then the supernatant was separated from the aqueous suspension, so that an aqueous suspension containing colloidal calcium carbonate particles 20 of 0.05 ~.m in size at a concentration of 15% by weight was obtained. In a . mixer, particle surfaces of colloidal calcium carbonate were treated by adding a 10% solution of sodium salt of fatty acid at an amount of 3 parts per 100 parts of CaC03 produced at a temperature of 90 °C. the suspension was concentrated through a filter press to a concentration of 55 % by weight of 2s solids, dried at a temperature of 80 °C, pulverized and classified to produce colloidal calcium carbonate powders of 0.05 ~m in particle size.
(Example 2) 3o Example 1 was repeated except that the time for ripening was 3 hours and the pH of the aqueous suspension was 9.5. The final product was powders of colloidal calcium carbonate having 0.06 ~,m particle size.
(Example 3) Example 1 was repeated except that the time for ripening was 4 hours and the pH of the aqueous suspension was 10.8. The final product was s powders of colloidal calcium carbonate having 0.07 pm particle size.
(Comparative Example 1 ) Example 1 was repeated except that the agitation of an aqueous to suspension was performed at a Reynolds number of 8,000. Powders of colloidal calcium carbonate, having 0.045 wm particle size, were obtained, however, the pH of a suspension after 2-hour-ripenning was 8.0 and the particle size of the product was not uniform.
is (Comparative Example 2) Example 1 was repeated except that the amount of KOH added was 2.0 part per 100 parts of Ca(OH)2. Powders of colloidal calcium carbonate, having 0.05 pm particle size, were obtained, however, the pH of a suspension ao after 2-hour-ripenning was 9.2 and the particle size of the product was not uniform.
(Reference Example 1 ) 2s According to a conventional process to carbonate an aqueous lime suspension, a gas containing 30 % by volume of carbon dioxide was added at a rate of 100 a per minute per kg of Ca(OH)2 to the aqueous lime suspension having a concentration of 5% by weight and a temperature of 15 "C.
Concentration, surface-treatment, dehydration, drying, pulverization and 3o classification were performed in the same manner as in Example 1 to give a powdery calcium carbonate product. The final product was powders of colloidal calcium carbonate having 0.04 ~,m particle size.
(Reference Example 2) The aqueous suspension carbonated by the process of Reference Example 1 was maintained and ripened for 100 hours while being heated to a s temperature of i i.,~~ ~~ ~,1~ i~_1 80 "C. Dehydration, dryring, pulverization and classification were performed in the same manner as in Reference Example 1 to give a powdery calcium carbonate product. The final product was powders of colloidal calcium carbonate having 0.08 ran particle size.
(Application Example) According to the formulation given below, each of calcium carbonate powders obtained in Examples 1 to 3, Comparative Examples 1 and 2 and Reference Examples 1 and 2 was added to DOP, a plasticizer of PVC paste resin, dispersed therein by a conventional method, kneaded by an automakic stirrer for 10 min., and measured with a method of Smm-thickness-slop and a grind gauge to know its grid.
'The measured results are listed in Table 1.
Formulation receipt Geon 1? l (polyvinylchloride paste resin) SOg DOP (dioctylphthalate) 60g Colloidal calcium carbonate SOg Table 1 Particle$ET Slope Grid Size(;.lm)Surface ''via ~ judge-~tm judge-Dispersity (m fig) merit merit Example 0.05 28 7 ~O 3 ~O (>
Example 0.06 25 1 UO 3 ~ O
Example 0.07 22 1 O~ 3 J
Comparativep 29 60 i~ 65 0,~5 Example .
Comparative0,05 27 70 n 70 =1. p Example Reference p.0~ 30 150 X 90 X X
Example Reference 0.08 20 80 X 60 ,~ X
Example Z
NOTE : The smaller the values of the slope and the grid are, the better their properties are ~: excellent ~: good !'~: average X : bad ,::~ ~, :~
It is evident from the above results that the process according to the present invention provides particles of colloidal calcium carbonate which show lower at~nity of aggregation, superior uniformity and dispersity in the end products.
These above examples are set forth to illustrate specifc embodiments of the invention and are not intended to limit the scope of the processes of the present invention. Additional embodiments and advantages within the scope of the claimed invention will be apparent to one of ordinary skill in the art.
Claims (3)
1. A process for preparing cubic particles of colloidal calcium carbonate having an average size in the range of 0.045 µm to 0.075 µm, by a step size of 0.005 µm, which process comprises the steps of:
(a) adding sugar or a chelating agent into an aqueous suspension of calcium hydroxide having a concentration of 3 to 8% by weight and a temperature of 14 °C to 18 °C, the amount of said sugar or said chelating agent added being 0.2 to 3.0 parts by weight per 100 parts by weight of calcium hydroxide contained in the aqueous suspension;
(b) introducing a gas containing 20 to 40% by volume of carbon dioxide into the aqueous suspension from step (a) at a rate of 40 to 200 liters per minute per kg of calcium hydroxide as the starting material to produce calcium carbonate particles having an average size of 0.04 µm when the pH of the suspension reaches 6.8;
(c) adding a hydroxide with a univalent or bivalent cation into the aqueous suspension from step (b) at an amount of 0.1 to 0.8 parts by weight per 100 parts by weight of calcium hydroxide as the starting material to neutralize the remaining carbonate ions therein;
(d) heating the aqueous suspension from step (c) up to a temperature of 40 °C to 95 °C and simultaneously agitating at a Reynolds number of 100 to 5,000, whereby the pH of said aqueous suspension is raised to a desirable value; and (e) introducing the same carbon dioxide-containing gas as used in step (b) into the aqueous suspension from step (d) to neutralize it.
(a) adding sugar or a chelating agent into an aqueous suspension of calcium hydroxide having a concentration of 3 to 8% by weight and a temperature of 14 °C to 18 °C, the amount of said sugar or said chelating agent added being 0.2 to 3.0 parts by weight per 100 parts by weight of calcium hydroxide contained in the aqueous suspension;
(b) introducing a gas containing 20 to 40% by volume of carbon dioxide into the aqueous suspension from step (a) at a rate of 40 to 200 liters per minute per kg of calcium hydroxide as the starting material to produce calcium carbonate particles having an average size of 0.04 µm when the pH of the suspension reaches 6.8;
(c) adding a hydroxide with a univalent or bivalent cation into the aqueous suspension from step (b) at an amount of 0.1 to 0.8 parts by weight per 100 parts by weight of calcium hydroxide as the starting material to neutralize the remaining carbonate ions therein;
(d) heating the aqueous suspension from step (c) up to a temperature of 40 °C to 95 °C and simultaneously agitating at a Reynolds number of 100 to 5,000, whereby the pH of said aqueous suspension is raised to a desirable value; and (e) introducing the same carbon dioxide-containing gas as used in step (b) into the aqueous suspension from step (d) to neutralize it.
2. A process according to claim 1, wherein the specific particle size of the colloidal calcium carbonate finally obtained depends on the pH of the aqueous suspension reached at the end of (d).
3. A process according to clams 1 or 2 which process further comprises:
concentrating the aqueous suspension from step (e) up to a concentration of 14~1 % by weight of the colloidal calcium carbonate particles; and admixing said concentrated suspension with a surface-treating agent and then subjecting it to dehydration, drying and pulverization to obtain dry colloidal calcium carbonate powder.
concentrating the aqueous suspension from step (e) up to a concentration of 14~1 % by weight of the colloidal calcium carbonate particles; and admixing said concentrated suspension with a surface-treating agent and then subjecting it to dehydration, drying and pulverization to obtain dry colloidal calcium carbonate powder.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019960002536A KR0184847B1 (en) | 1996-02-02 | 1996-02-02 | Process for preparing calcium carbonate |
| KR96-2536 | 1996-02-02 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2196124A1 CA2196124A1 (en) | 1997-08-03 |
| CA2196124C true CA2196124C (en) | 2000-12-19 |
Family
ID=19450652
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002196124A Expired - Fee Related CA2196124C (en) | 1996-02-02 | 1997-01-28 | Process for preparing colloidal calcium carbonate by particle size |
Country Status (5)
| Country | Link |
|---|---|
| KR (1) | KR0184847B1 (en) |
| CN (1) | CN1058684C (en) |
| AU (1) | AU691437B2 (en) |
| CA (1) | CA2196124C (en) |
| GB (1) | GB2309692B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9815289D0 (en) * | 1998-07-14 | 1998-09-09 | Unilever Plc | Speroidal calcitic calcium carbonate |
| JP4596148B2 (en) * | 2005-05-18 | 2010-12-08 | 信越化学工業株式会社 | Room temperature curable organopolysiloxane composition |
| EP3127867B1 (en) * | 2014-03-31 | 2020-08-05 | Nippon Paper Industries Co., Ltd. | Manufacturing method for calcium-carbonate microparticles |
| CN103897434B (en) * | 2014-04-19 | 2016-03-30 | 芮城新泰纳米材料有限公司 | The preparation method that plastic master batch is Nano calcium carbonate dedicated |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52126697A (en) * | 1976-04-16 | 1977-10-24 | Toyo Soda Mfg Co Ltd | Production of chain calcium carbonate |
| JPS5343694A (en) * | 1976-10-01 | 1978-04-19 | Shiraishi Kogyo Kaisha Ltd | Process for producing cubic calcium carbonate having 0*111*0micron size |
| JPH01230424A (en) * | 1988-03-09 | 1989-09-13 | Shiraishi Chuo Kenkyusho:Kk | Calcium carbonate, calcium carbonate pigment, production thereof, coating composition therefrom for information recording paper and information recording paper coated therewith |
| US5332564A (en) * | 1992-07-10 | 1994-07-26 | Ecc International Inc. | Process for production of rhombic shaped precipitated calcium carbonate |
| JP3055334B2 (en) * | 1992-11-16 | 2000-06-26 | 菱光石灰工業株式会社 | Method for producing colloidal calcium carbonate |
-
1996
- 1996-02-02 KR KR1019960002536A patent/KR0184847B1/en not_active IP Right Cessation
-
1997
- 1997-01-22 AU AU12277/97A patent/AU691437B2/en not_active Ceased
- 1997-01-28 CA CA002196124A patent/CA2196124C/en not_active Expired - Fee Related
- 1997-01-31 CN CN97102401A patent/CN1058684C/en not_active Expired - Fee Related
- 1997-01-31 GB GB9702081A patent/GB2309692B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| GB2309692A (en) | 1997-08-06 |
| CN1058684C (en) | 2000-11-22 |
| GB2309692B (en) | 1998-03-04 |
| AU691437B2 (en) | 1998-05-14 |
| KR970061783A (en) | 1997-09-12 |
| CA2196124A1 (en) | 1997-08-03 |
| CN1163860A (en) | 1997-11-05 |
| KR0184847B1 (en) | 1999-04-15 |
| GB2309692A8 (en) | 1997-09-11 |
| AU1227797A (en) | 1997-08-28 |
| GB9702081D0 (en) | 1997-03-19 |
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