JP5574325B2 - Method for producing spherical calcium carbonate - Google Patents

Description

  The present invention relates to a method for producing a vaterite spherical calcium carbonate.

  Calcium carbonate crystals include hexagonal calcite, orthorhombic aragonite, and pseudohexagonal (spherical) vaterite. Of these, the calcite form and the aragonite form (FIG. 1) exist in nature and are commercially available stable crystal forms, whereas the vaterite form does not exist in nature and is considered unstable. . However, spheroidizing calcium carbonate improves various properties such as calcium carbonate filling properties, dispersibility, and polishing properties, and provides preferable properties. Therefore, spherical calcium carbonate is required in various fields. .

  Calcium carbonate is blended in foundations, face powders, makeup cosmetics, etc., but if there is a lot of calcite-type calcium carbonate with large particle size variation and friction, the initial adhesion amount when applied to the skin There was a tendency to increase, the thickness became non-uniform, the feel was poor and there was a problem with the feeling of use. On the other hand, cosmetics and the like in which calcium carbonate having a uniform particle diameter, vaterite-type calcium carbonate, etc. are blended are said to show a good feeling of use.

  As a conventional method for obtaining spherical calcium carbonate in the form of vaterite, for example, a method in which a calcium hydroxide salt and carbonate are reacted at a temperature of about 80 ° C. in the presence of a divalent cation other than calcium (Patent Document 1), an additive In the presence of, a method of introducing carbon dioxide gas into a calcium hydroxide slurry under a specific pH environment (Patent Document 2), a strictly controlled dendrimer is blended with a raw material at a specific concentration, A method of reacting calcium chloride and carbon dioxide gas at a temperature and a specific pH range (Patent Document 3) has been reported. However, these methods have problems such as time-consuming synthesis, difficulty in mass production, high production costs, and inability to stably obtain only the vaterite type, and there is no method that should be satisfied. Is the current situation.

  In Patent Documents 4 and 5, a W / O emulsion having an aqueous phase containing a raw material as a dispersed phase is prepared by passing through a microporous membrane, and further mixed with an aqueous phase containing the raw material to form a spherical shape. A method for producing silica or the like is disclosed. However, there is no suggestion or disclosure about the use for producing spherical calcium carbonate.

JP-A-57-92520 JP 05-294616 A JP 2003-63819 A Japanese Patent No. 2555475 JP 2008-247696 A

  An object of the present invention is to provide a method for producing vaterite spherical calcium carbonate particles which is easy and low in cost.

  In order to solve the above-mentioned problems, the inventors have intensively studied. As a result, an O / W emulsion in which an oil phase is dispersed in an aqueous solution containing calcium ions and an aqueous solution containing carbonate ions are used as raw materials. By adopting the membrane permeation method used, it was found that spherical calcium carbonate particles can be easily produced at low cost, and the present invention has been completed here.

  That is, the present invention provides the following method for producing spherical calcium carbonate.

  Item 1. A method for producing spherical calcium carbonate, in which an O / W emulsion composed of a continuous aqueous phase in which calcium ions are dissolved and an organic phase is passed through a porous membrane and then reacted with an aqueous solution containing carbonate ions.

  Item 2. Item 2. The production method according to Item 1, wherein the porous membrane is a porous membrane produced by a phase separation method.

  Item 3. Item 3. The method according to Item 1 or 2, wherein the porous membrane is a hydrophobic porous membrane.

  Item 4. Item 4. The production method according to any one of Items 1 to 3, wherein the porous membrane has a pore diameter of 10 to 20 µm.

  Item 5. Item 5. The production method according to any one of Items 1 to 4, wherein the volume ratio of the continuous aqueous phase to the organic phase of the O / W emulsion is 1: 1 to 13: 2.

  The production method of the present invention enables mass production of spherical calcium carbonate particles easily and at low cost. Moreover, since the manufacturing method of this invention can select suitably the porous membrane which has various pore diameters controlled strictly, it is possible to manufacture the spherical calcium carbonate of a desired particle diameter. It is also possible to produce spherical calcium carbonate with a narrow particle size distribution.

The SEM image of the calcium carbonate which has a crystal structure of a calcite form and an aragonite form. 2 is an SEM image of calcium carbonate prepared according to Example 1. FIG. The X-ray-diffraction result of the calcium carbonate produced by Example 1. FIG. 3 is an SEM image of calcium carbonate prepared according to Example 2. FIG. The X-ray-diffraction result of the calcium carbonate produced by Example 2. FIG. 3 is an SEM image of calcium carbonate prepared according to Example 3. FIG. The X-ray-diffraction result of the calcium carbonate produced by Example 3. FIG. The particle diameter measurement result of the calcium carbonate produced by Example 4. FIG.

  The method for producing spherical calcium carbonate of the present invention is a method in which an O / W emulsion comprising a continuous aqueous phase in which calcium ions are dissolved and an organic phase is allowed to react with an aqueous solution containing carbonate ions after passing through a porous membrane. It is.

The O / W emulsion used in the production method of the present invention is an O / W emulsion in which an oil agent (organic phase) is dispersed in an aqueous solution (continuous aqueous phase) containing calcium ions and a surfactant. Become.

  The compound serving as the calcium ion source contained in the continuous aqueous phase is not particularly limited as long as it has a property of dissolving in the aqueous phase and does not impair the formation of the O / W emulsion. Specific examples include organic acid calcium such as calcium chloride, calcium acetate and calcium lactate, and inorganic acid calcium such as calcium nitrate and calcium perchlorate, and calcium chloride is particularly preferably used. These compounds may be used alone or in admixture of two or more. The calcium ion concentration in the aqueous solution is not particularly limited, but can usually be a concentration of about 0.1 to 3 mol / L.

  The surfactant used in preparing the aqueous solution containing the calcium ion and the surfactant is a water-soluble surfactant, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, or a nonionic surfactant. It is not particularly limited as long as an agent or the like can be used and an O / W emulsion can be produced, and it is preferable to use polyoxyethylene sorbitan monolaurate which is an amphoteric surfactant. These surfactants may be used alone or in admixture of two or more. The amount of the surfactant used is not particularly limited, but can usually be about 0.5 to 3% by weight with respect to the continuous aqueous phase.

  The above oil agent is not particularly miscible with water, and is particularly capable of forming an O / W emulsion by forming a dispersed oil phase in an aqueous solution containing calcium ions and a surfactant. It is not limited. Specific examples include organic solvents that are not miscible with water, such as hexane, toluene, cyclohexane, xylene, and benzene. It is particularly preferable to use hexane. These oil agents may be used alone or in admixture of two or more.

  The volume ratio of the aqueous solution (W) containing the calcium ions and the surfactant and the oil agent (O) can be set within a range in which spherical calcium carbonate can be efficiently produced, and spherical calcium carbonate particles. It is possible to set the diameter within a range in which a desired distribution is obtained. Usually, it can be set in a range of about W: O = 1: 1 to 13: 2. A more preferable range is about W: O = 7: 3 to 5: 2.

  In the production method of the present invention, after mixing the above aqueous solution containing calcium ions and a surfactant and the above oil agent, an O / W emulsion can be prepared using a known method. Examples thereof include a method of irradiating the mixed solution with ultrasonic waves, a method of stirring using a homogenizer or a stirrer, and the like. In the present invention, a method of stirring using a homogenizer is preferable. An O / W emulsion having a smaller particle diameter can be produced as the number of stirring rotations is increased. Here, the number of rotations during stirring is not particularly limited as long as O / W having a suitable particle diameter can be produced. Specifically, it can be set to about 2,000 to 20,000 rpm. More preferably, it is 5,000-18,000 rpm. More preferably, it is about 9,000-15,000 rpm.

As the porous membrane used in the production method of the present invention, any porous membrane can be adopted as long as pores of a predetermined size penetrate from one side to the other. The shape of the pores may be any shape such as a columnar shape, a prismatic shape, or a funnel shape. Further, the pores may penetrate perpendicularly or obliquely with respect to the film surface, or they may be entangled. Furthermore, the shape and structure of the porous membrane itself are not particularly limited. Specific examples of the shape include a pipe shape and a flat membrane shape, and examples include a symmetric membrane or an asymmetric membrane, a homogeneous membrane or a non-homogeneous membrane. The material of the porous film is not particularly limited, and examples thereof include glass, ceramics, silicon, polymer, and metal.

As a suitable porous membrane used in the production method of the present invention, use of a porous membrane obtained by a phase separation method is exemplified. Specifically, CaO—B ₂ O ₃ —SiO ₂ —Al ₂ O ₃ —Na ₂ O porous glass film, MgO—CaO—B ₂ O ₃ —SiO ₂ —Al ₂ O ₃ —Na ₂ O porous Examples thereof include a porous glass film and a Na ₂ O—K ₂ O—CaO—Al ₂ O ₃ —B ₂ O ₃ —ZrO ₂ —SiO ₂ porous glass film. The porous membrane obtained by the phase separation method is characterized by having a uniform pore diameter, the shape of the pore diameter being strictly controlled, and the pore diameter cross section being cylindrical.

  The above-mentioned uniform pore diameter is the pore diameter (φ10) when the pore diameter of the porous membrane body occupies 10% of the whole in the relative cumulative pore distribution curve, and the pore volume is 90% of the whole. The case where the value of the quotient obtained by dividing by the pore diameter (φ90) when occupied is in the range of about 1 to 1.5.

  The pore diameter of the porous membrane used in the production method of the present invention means the pore diameter when the through-pore diameter volume accounts for 50% of the total in the relative cumulative pore diameter distribution curve.

  The porous film obtained by the above phase separation method can be produced by the method described in JP-A No. 57-140334 or JP-A No. 61-40841. Specifically, the basic glass, which is a raw material for the porous glass film, can be produced by treating the base glass at 600 to 800 ° C. for 2 to 24 hours and then eluting and removing the acid-soluble component.

  The porous membrane obtained by the above phase separation method can be appropriately obtained from various pore diameter lineups under the trade name “SPG membrane” sold by SPG Techno Co., Ltd. and used.

  Some of the above porous membranes have hydrophobicity, but many of them have polar groups such as —SiOH groups and —OH groups on the surface of the pores, and some of them are hydrophilic. . In the production method of the present invention, a hydrophobic membrane may be used by subjecting the porous membrane to a hydrophobic treatment in advance. The hydrophobicity of the porous membrane means a state in which the contact angle between the surface of the porous membrane and the aqueous solution exceeds 90 ° and the porous membrane does not get wet with the aqueous solution.

  The hydrophobic treatment method is not particularly limited as long as the calcium carbonate can be suitably produced without blocking the pores in the porous membrane when the O / W emulsion passes through the porous membrane. Is not to be done. Specifically, a method of chemically adsorbing a hydrophobizing agent on the entire surface of the porous film including the surface of the pores, a method of chemically bonding the hydrophobizing agent, a method of forming a physically uniform hydrophobizing agent film, etc. Can be mentioned.

  Examples of the hydrophobizing agent include thermosetting silicone oils such as dimethylpolysiloxane and methylhydrogenpolysiloxane, silicone resins such as silicone emulsion and silicone resin, methyltrimethoxysilane, hexamethyldisilazane, and vinyltrimethoxysilane. , Silane coupling agents such as trimethylcolorosilane, cyclic silicone compounds such as dihydrogenhexamethylcyclotetrasiloxane, trihydrogenbentamethylcyclotetrasiloxane, isopropyltristearoyl titanate, isopropyltri (N-aminoethyl-) titanate, etc. Titanate coupling agents, aluminum coupling agents such as acetoalkoxyaluminum diisopropylate, fluorine silicone coating agents, Motokei coating agents and the like can be suitably used. These hydrophobizing agents can be used alone or in combination of two or more. The degree of hydrophobicity using these hydrophobizing agents may be such that the hydrophobicity is not impaired when the solution containing the O / W emulsion passes through the pores.

  The pore diameter of the porous membrane used in the production method of the present invention can be appropriately selected according to the desired spherical calcium carbonate particle diameter, O / W emulsion particle diameter, and the like. Usually, the pore diameter can be about 10 to 20 μm. More preferably, it is about 14 to 16 μm. The film thickness of the porous film is not particularly limited as long as it has sufficient strength against the pressure applied when passing the solution containing the emulsion, but it is usually about 400 μm to 1 mm. be able to.

  In the production method of the present invention, when passing the O / W emulsion through the porous membrane, pressure may be applied. The range of pressure to be applied is not particularly limited as long as it can efficiently produce spherical calcium carbonate without physically or chemically damaging the porous membrane, O / W emulsion, etc. Absent. When the applied pressure is weak, the O / W emulsion cannot pass through the porous membrane, or cannot form a spherical shape well at the outlet of the pores, and a distorted calcium carbonate is produced, which is not preferable. .

  The pressure to be applied can be appropriately set according to various conditions such as the particle diameter of the O / W emulsion, the viscosity, and the pore diameter of the porous membrane. For example, the pressure applied when a porous film having a pore diameter of 10 μm is used can usually be about 0.011 MPa or more. In the case of using a hydrophobic porous membrane having a pore diameter of 15 μm, it can be usually about 0.009 MPa or more. In the case of using a hydrophobic porous membrane having a pore size of 20 μm, it can be usually about 0.004 MPa or more. Note that the upper limit value of the pressure to be applied is appropriately set as long as the porous film and the O / W emulsion are not affected as described above.

  The compound that becomes a carbonate ion source in the preparation of the aqueous solution containing carbonate ions of the present invention is not particularly limited as long as it becomes a raw material for spherical calcium carbonate. Specific examples include alkali metal carbonates such as sodium carbonate, potassium carbonate, and lithium carbonate, and sodium carbonate is particularly preferably used. These compounds may be used alone or in admixture of two or more. The concentration of carbonate ions in the aqueous solution is not particularly limited, and can usually be about 0.1 to 1 mol / L.

  The spherical calcium carbonate produced by the production method of the present invention can be recovered as a precipitate. The recovery method is not particularly limited, and the liquid phase can be removed and recovered by using a known method such as centrifugal sedimentation, decantation, filtration, or evaporation. The recovered spherical calcium carbonate can be washed using a known method.

  The manufacturing method of this invention can be normally performed at the temperature of about 0-50 degreeC. More preferably, it is about 15-35 degreeC.

  The production method of the present invention is desired by appropriately changing various conditions such as the particle diameter of the above-mentioned O / W emulsion, the pore diameter of the hydrophobic porous membrane, and the pressure when passing through the O / W emulsion. It is possible to produce spherical calcium carbonate having a particle size of Specifically, spherical calcium carbonate having a particle diameter of about 0.1 to 50 μm can be produced. More preferably, spherical calcium carbonate having a particle diameter of about 0.5 to 20 μm, most preferably about 1 to 15 μm can be produced.

  Since the production method of the present invention can produce spherical calcium carbonate according to the pore size of the porous membrane, the production of spherical calcium carbonate with a narrow particle size distribution is achieved by using a porous membrane with a strictly controlled pore size. can do. For example, the coefficient of variation calculated with respect to the particle diameter of the spherical calcium carbonate to be produced can be usually made to be about 0.5 to 10%. More preferably, it is about 0.8 to 1.5%. The coefficient of variation referred to here is the percentage value of the quotient obtained by dividing the standard deviation of the obtained spherical calcium carbonate particles by the average particle diameter.

  The production method of the present invention can obtain spherical calcium carbonate in a yield of 60 to 90%. More preferably, it is 80 to 90%.

  Furthermore, the spherical calcium carbonate produced by the production method of the present invention is composed of an aggregate of microcrystals and is a porous material. Therefore, it is conceivable to carry a drug or an agrochemical and use it as an adsorbent or a filler.

  Hereinafter, the present invention will be described in detail. However, it goes without saying that the present invention is not limited to the following examples.

  A hydrophobic porous membrane (hereinafter referred to as a hydrophobic SPG membrane) used as a porous membrane in the following examples or comparative examples is a water-soluble organic SPG membrane manufactured by SPG Techno Co., Ltd. having a pore diameter of 15 μm. A silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd .; KP-18C) was immersed in an aqueous solution containing 10% by weight for 24 hours and then dried in an electric furnace at 110 ° C. for 24 hours. Further, the hydrophilic porous membrane (hereinafter referred to as hydrophilic SPG membrane) was used as it was without any treatment on the SPG membrane manufactured by SPG Techno Co. having a pore diameter of 15 μm.

Example 1
The emulsion used for the production of spherical calcium carbonate uses either an O / W emulsion or a W / O emulsion which is suitable for producing spherical calcium carbonate, and uses a porous film of a hydrophilic SPG film or a hydrophobic SPG film. In order to clarify whether this is suitable, four combinations were examined.

  Tween 60, which is a hydrophilic surfactant, is dissolved in 0.056% by weight calcium chloride aqueous solution to form an aqueous phase, and hexane, which is an oil agent, is added in the same volume as the aqueous phase, and then a homogenizer is used at room temperature. The O / W emulsion was prepared by dispersing an oil phase containing hexane in a continuous aqueous phase having calcium ions.

  Then, the cylindrical SHC membrane or the hydrophilic SPG membrane produced by the above-described method was immersed in 200 ml of a 0.015% by weight aqueous sodium carbonate solution stirred at 600 rpm with a stirrer chip. Subsequently, 20 ml of the O / W emulsion prepared in advance was added to the inside of the cylinder, 0.03 Mpa of nitrogen gas was applied to the inside of the cylinder, and the O / W emulsion was applied to each of the hydrophobic and hydrophilic SPG films. Calcium carbonate was prepared by allowing it to pass through and reacting at room temperature in an aqueous sodium carbonate solution outside the tube. The produced calcium carbonate particles were manufactured by ADVANTEC No. It was collected by suction filtration using 5C filter paper. In order to remove the surfactant and the like remaining on the recovered calcium carbonate particles, the product was washed with alcohol. The yield of the obtained calcium carbonate was about 62%.

Comparative Example 1
Calcium carbonate as in Example 1 except that tetraglycerin condensed ricinoleic acid ester (TGCR) was used as a surfactant and a W / O emulsion in which an aqueous solution containing calcium ions was dispersed in a continuous oil phase was prepared. Was made.

  The SEM image of the calcium carbonate obtained by Example 1 and Comparative Example 1 is shown in FIG. When the W / O emulsion was used, crystals of calcium carbonate having a unique shape that was neither spherical calcium carbonate nor conventional calcite-type calcium carbonate were obtained. On the other hand, when an O / W emulsion was used, a large amount of vaterite-type spherical calcium carbonate was obtained, which proved to be a suitable method for producing spherical calcium carbonate.

  In particular, it was found that the method using a hydrophobic SPG film produced fewer calcite crystals than the result using a hydrophilic SPG film, and was a more preferable method for producing spherical calcium carbonate.

  FIG. 3 represents the X-ray crystal diffraction pattern of the spherical calcium carbonate obtained in Example 1. The square (□) in the figure represents a peak due to calcite (cubic) calcium carbonate, and the circle (○) in the figure represents a peak due to a vaterite (pseudohexagonal; vaterite). Represents that.

The one using the hydrophilic SPG film shown in the upper part of FIG. 3 has a higher calcite-type peak value, while the one using the hydrophobic SPG film shown in the lower part of FIG. It was revealed that the peak value represented was high. Further, the peak value of 2 [Theta] = 29.34 ° showing the peaks characteristic of calcite type, when using the parent aqueous SPG film shown in the upper part of FIG. 3 is 6,710, in the lower part of FIG. 3 when using the hydrophobicity SPG film shown it has been found that is 3,450. Therefore, similarly to the result of the SEM image in FIG. 2, it was revealed that the method using the hydrophobic SPG film is a method capable of obtaining spherical calcium carbonate more suitably.

Example 2
The influence of the O / W emulsion obtained by the number of rotations when producing the O / W emulsion on the finally obtained calcium carbonate was examined. Examples except that each O / W emulsion obtained using a homogenizer rotation speed of 13,500, 9,500, or 17,500 rpm when producing an O / W emulsion was used, and a hydrophobic SPG membrane was further used. In the same manner as in Example 1, calcium carbonate was prepared. The SEM image of the produced spherical calcium carbonate and the results of X-ray analysis are shown in FIGS. 4 and 5, respectively.

  From the results of FIG. 4, the shape of the obtained calcium carbonate is 13,500 rpm and the shape of the calcium carbonate produced by the method using the O / W emulsion produced at 9,500 rpm is the vaterite type. On the other hand, in the result of using the O / W emulsion prepared at a rotational speed of 17,500 rpm, there are also vaterite-type crystals, but calcite-type calcium carbonate is seen. It was.

  In FIG. 5, as in FIG. 3, a square (□) in the figure represents a peak due to calcite-type calcium carbonate, and a circle (◯) represents a peak due to a vaterite form.

  When an O / W emulsion prepared under the conditions of 13,500 rpm shown in the upper part of FIG. 5 and 9,500 rpm shown in the middle part of FIG. 5 is used, it is shown in the lower part of FIG. The peak value representing the vaterite crystals is higher than when using the O / W emulsion produced under the condition of 17,500 rpm, and it is clear that many vaterite calcium carbonate crystals can be obtained. became.

  Further, the peak value of 2θ = 29.34 ° representing the peak peculiar to the vaterite shape is 3,450 when the rotational speed is 13,500 rpm, and 5,283.33 when the rotational speed is 9,500 rpm. On the other hand, when the rotational speed was 17,500 rpm, the peak value was as large as 11,296.7, indicating that many calcite-type calcium carbonate crystals were contained.

  In this example, an SPG membrane having a pore diameter of 15 μm is used, and the O / W emulsion produced at a rotational speed of 17,500 rpm is continuous to pass through the hydrophobic SPG membrane without causing phase transformation. It is considered that it is difficult to form spherical calcium carbonate because the aqueous phase of the layer reacted as it is in a sodium carbonate solution.

Example 3
In the preparation of the O / W emulsion, the volume ratio of the raw material aqueous phase to the oil phase was examined. The volume ratio of the water phase and the oil phase used in Example 1 was 4: 4, 6: 2, and 7: 1, respectively, and stirred at 13,500 rpm to prepare an O / W emulsion. A hydrophobic SPG membrane was used. Except for the above, calcium carbonate was prepared using the same method as in Example 1. The results are shown in FIGS.

  From the result of the SEM image in FIG. 6, both of the calcium carbonate crystals produced by the method using the W / O emulsion produced by setting the volume ratio of the water phase and the oil phase to 4: 4 and 6: 2, respectively, Most of the crystals are vaterite crystals, and it has become clear that this is a suitable method for producing spherical calcium carbonate. On the other hand, the calcium carbonate crystals produced by the method using the W / O emulsion produced with a volume ratio of the water phase to the oil phase of 7: 1 are dotted with calcite crystals, The volume ratio of the oil phase was inferior to that produced by the ratio of 4: 4 or 6: 2.

  FIG. 7 is a diagram illustrating an X-ray analysis pattern of calcium carbonate prepared according to the volume ratio of each aqueous phase and oil phase in Example 3. As in FIG. 3 or FIG. 5, the square (□) in the figure represents a peak due to calcite-type calcium carbonate, and the circle (◯) represents a peak due to a vaterite form.

  An O / W emulsion produced under the condition that the volume ratio of the water phase and the oil phase shown in the upper part of FIG. 7 is 4: 4 and the volume ratio of the water phase and the oil phase shown in the middle part of FIG. 7 is 6: 2. Is used, the peak value representing the vaterite crystals is higher than when using an O / W emulsion produced under the condition that the volume ratio of the oil phase shown in the lower part of FIG. 7 is 7: 1. It became clear that many vaterite-type calcium carbonate crystals were obtained.

  In addition, the peak value of 2θ = 29.34 ° representing a peak peculiar to the vaterite shape is 3450 when the volume ratio of the water phase to the oil phase is 4: 4, and the volume ratio of the water phase to the oil phase is 6: 2. Is 3321.67, whereas when the volume ratio of the aqueous phase to the oil phase is 1: 7, it shows a large peak value of 8934, indicating that there are many calcite-type calcium carbonate crystals. It was.

Example 4
Of the spherical calcium carbonate obtained in Example 3 above, the average of the raw materials for O / W emulsion preparation obtained as the water phase: oil phase volume ratio of 4: 4 and those obtained as 6: 2 The particle size and its distribution were measured. The results are shown in FIG.

  The calcium carbonate particles obtained with an aqueous phase: oil phase volume ratio of 6: 2 have a narrower particle size distribution than the aqueous phase: oil phase volume ratio of 4: 4. It was found that calcium carbonate having a uniform particle size can be obtained. The average value of the particle diameter of calcium carbonate obtained by setting the volume ratio of water phase: oil phase to 6: 2 was 6.57 μm, the standard deviation was 0.31, and the coefficient of variation was calculated to be about 4.7%. The average value of the particle diameter of calcium carbonate obtained by setting the volume ratio of water phase: oil phase to 6: 2 was 9.01 μm, the standard deviation was 0.09, and the coefficient of variation was calculated to be about 1.0%.

  The spherical calcium carbonate obtained by the production method of the present invention can be used in many fields such as cosmetics.

Claims (3)

In a method for producing spherical calcium carbonate, an O / W emulsion composed of a continuous aqueous phase in which calcium ions are dissolved and an organic phase is passed through a hydrophobic porous membrane and then reacted with an aqueous solution containing carbonate ions. And the manufacturing method whose volume ratio of the continuous water phase of an O / W emulsion and an organic phase is 1: 1-13: 2. The manufacturing method according to claim 1, wherein the porous film is a porous film manufactured by a phase separation method. The manufacturing method according to claim 1 or 2, wherein the porous membrane has a pore diameter of 10 to 20 µm.

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