Method of manufacturing calcite-type calcium carbonate granule

Abstract

To provide a method of manufacturing with a high yield in a simple process calcium carbonate having a controlled particle size and a controlled hole.SOLUTION: A method for manufacturing calcite-type calcium carbonate granules comprises the steps of: mixing, heating, and agitating calcite-type calcium carbonate particles, gelatin, and water to obtain a gelatin / calcite-type calcium carbonate particle mixed slurry A; dissolving a surfactant in oil and agitating the mixture to obtain a solution B; mixing and agitating the gelatin / calcite-type calcium carbonate particle mixed slurry A and the solution B to obtain an emulsified liquid C; adding a cross-linking agent to the emulsified liquid C and agitating to obtain an emulsified liquid D containing gelatin / calcite-type calcium carbonate composite particles; centrifuging the emulsified liquid D containing the gelatin / calcite-type calcium carbonate composite particles to obtain the gelatin / calcite-type calcium carbonate composite particles; and calcining the gelatin / calcite-type calcium carbonate composite particles to obtain calcite-type calcium carbonate granules.SELECTED DRAWING: Figure 1-A

Description

Technical Field

[0001] The present invention relates to a method for producing calcite-type calcium carbonate particles.

Background Art

[0002] Calcium carbonate is widely used as a reinforcing filler for rubber, plastic, paper, sealant, paint / ink, etc., a calcium fortifier for food, feed, etc., and an alkaline agent in fertilizers. Calcium carbonate used in these applications is roughly classified into precipitated calcium carbonate obtained by blowing carbon dioxide gas into an aqueous suspension of calcium hydroxide to carry out a carbonation reaction, and heavy calcium carbonate obtained by mechanically pulverizing and classifying high-quality limestone.

[0003] It is known that calcium carbonate has three types of crystal phases: calcite, aragonite, and vaterite. Among these, calcite is the most stable crystal phase. For example, vaterite gradually transforms into calcite over time. Calcite-type calcium carbonate generally has rhombohedral or cubic crystals and has a dense structure. That is, calcium carbonate with a higher-order structure crystallized by a conventional method mostly becomes stable calcite crystals having a rhombohedral or cubic shape. If calcite-type calcium carbonate having a structure other than such a rhombohedral or cubic shape, for example, a spherical or porous structure with pores, can be obtained, it has high industrial utility value. Therefore, there is a demand for efficiently producing calcium carbonate having a calcite-type crystal phase and a desired particle size and shape.

[0004] Patent Document 1 discloses that spherical calcium carbonate with an average particle diameter of 11 μm or more and 20 μm or less, which does not contain aggregates of fine particles, was produced by introducing carbon dioxide gas into an aqueous calcium hydroxide suspension by a carbonation method. The spherical calcium carbonate obtained by the method of Patent Document 1 does not have a porous structure, and the production method is quite complicated, such as requiring special exhaust facilities, etc. Furthermore, the method of Patent Document 1 requires treatment of unreacted carbon dioxide gas, and it can be said that there is some difficulty in terms of safety. On the other hand, Patent Document 2 discloses a method of obtaining spherical calcium carbonate fine particles with a crystallite size of 3 nm to 30 nm by reacting an aqueous calcium chloride solution, an aqueous sodium carbonate solution, and an aqueous glycine solution using a solution method. The method of Patent Document 2 mainly aims at the production of wadalite-type calcium carbonate, and the fine particles obtained by the method of Patent Document 2 are a mixture of wadalite, calcite, and amino acid.

[0005] Patent Document 3 discloses a method of producing a synthetic calcium carbonate-based spherical porous granule with a particle diameter of 10 mm or less. Starting from synthetic calcium carbonate with a particle diameter of 0.1 μm or less, a desired amount of water and calcium oxide and / or calcium hydroxide as a granulation aid are added thereto to granulate into a spherical granule with a particle diameter of 10 mm or less. After granulation, a carbonation step is performed. In the method of Patent Document 3, it is necessary to cause and complete carbonation on the surface of the calcium carbonate powder, which is always difficult. In the method of Patent Document 3, the granulation aid may remain after the reaction, and the target synthetic calcium carbonate-based spherical porous granule can be obtained only when the reaction conditions are carefully controlled. Patent Document 4 discloses a method of obtaining fine spherical particles of calcium carbonate by using spherical micelles formed by polyvinylpyrrolidone (PVP) and polyoxyethylene sorbitan monooleate (Tween-80) as a template, reacting calcium chloride and sodium carbonate on this surface to obtain calcium carbonate, and drying it in an oven at about 80 °C. The fine spherical particles of calcium carbonate obtained by the method of Patent Document 4 are a mixture of calcite and wadalite.

[0006] On the other hand, attempts have also been made to produce spherical hollow bodies as calcium carbonate particles having a more complex structure. Patent Document 5 discloses that by using the gas bubble interface synthesis method, calcium ions and carbonate ions are reacted at the interface of gas bubbles of carbon dioxide to obtain hollow spherical calcium carbonate particles composed of a porous shell. Non-Patent Document 1 discloses that by using the currently most common template method, the surface of polystyrene beads is covered with a microemulsion supersaturated with calcium hydrogen carbonate and then subjected to high-temperature firing to produce a porous hollow body of aragonite-type calcium carbonate.

[0007] The method of Patent Document 5 requires strict control of the gas amount, and there are also problems with the safety of unreacted gas. In addition, the obtained calcium carbonate is of the vaterite type and has low stability in water. The method of Non-Patent Document 1 requires the preparation of a template in advance, and it is difficult for the microemulsion to coat the surface of the template. If this does not occur, there is a problem that a porous hollow body cannot be stably obtained. Furthermore, the calcium carbonate spherical hollow body obtained by the method of Non-Patent Document 1 is aragonite-type calcium carbonate.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Non-Patent Documents

[0009]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] Therefore, the present invention aims to provide a novel method for producing calcite - type calcium carbonate granules having a controlled particle size and controlled pores in a high yield through a relatively simple process different from the conventional ones, using calcite - type calcium carbonate as a raw material.

Means for Solving the Problems

[0011] Aspects of the present invention include the following steps: Mixing calcite - type calcium carbonate particles, gelatin, and water, and heating and stirring to obtain a gelatin / calcite - type calcium carbonate particle mixed slurry A: Dissolving a surfactant in oil and stirring to obtain a solution B: Mixing the gelatin / calcite - type calcium carbonate particle mixed slurry A and the solution B and stirring to obtain an emulsion C: Adding a cross - linking agent to the emulsion C and stirring to obtain an emulsion D containing gelatin / calcite - type calcium carbonate composite particles: Centrifuging the emulsion D containing gelatin / calcite - type calcium carbonate composite particles to obtain gelatin / calcite - type calcium carbonate composite particles; and Firing the gelatin / calcite - type calcium carbonate composite particles to obtain calcite - type calcium carbonate granules This is a method for producing calcite - type calcium carbonate granules.

[0012] Here, in the gelatin / calcite - type calcium carbonate particle mixed slurry A, the mass ratio of gelatin to calcite - type calcium carbonate particles is preferably in the range of 5:10 - 25:10.

[0013] In solution B, it is preferable that the volume ratio of the surfactant to the oil is in the range of 1:100 to 5:100.

[0014] It is preferable that the volume ratio of the gelatin / calcite calcium carbonate particle mixed slurry A to solution B is in the range of 1:10 to 10:10.

[0015] It is preferable to add a crosslinking agent to the emulsion C such that the mass ratio of gelatin to the crosslinking agent is in the range of 4:1 to 30:1.

[0016] It is preferable to bake the gelatin / calcite calcium carbonate composite particles at a temperature of 530°C or higher and lower than 650°C.

Advantages of the Invention

[0017] The production method of the present invention can produce calcite calcium carbonate granules with a high yield in a relatively simple process. By loading various drugs and the like into the pores of the produced calcite calcium carbonate, it can be used in drug delivery systems, cosmetic additives, food additives, health foods, catalyst carriers, and the like.

Brief Description of the Drawings

[0018]

Figure 1-A

Figure 1-B

Figure 2

Figure 3

Figure 4

Figure 5-A

Figure 5-B

Figure 6

Mode for Carrying Out the Invention

[0019] The embodiments of the present invention will be described in more detail, but the present invention is not limited only to the following embodiments.

[0020] One embodiment includes the following steps: A step of mixing calcite-type calcium carbonate particles, gelatin, and water, heating and stirring to obtain a gelatin / calcite-type calcium carbonate particle mixed slurry A: A step of dissolving a surfactant in oil and stirring to obtain a solution B: A step of mixing the gelatin / calcite-type calcium carbonate particle mixed slurry A and the solution B and stirring to obtain an emulsion emulsion C: A step of adding a crosslinking agent to the emulsion emulsion C and stirring to obtain an emulsion D containing gelatin / calcite-type calcium carbonate composite particles: A step of centrifuging the emulsion D containing gelatin / calcite-type calcium carbonate composite particles to obtain gelatin / calcite-type calcium carbonate composite particles; and A step of firing the gelatin / calcite-type calcium carbonate composite particles to obtain calcite-type calcium carbonate particles A method for producing calcite-type calcium carbonate particles, including

[0021] Calcium carbonate is a carbonate of calcium represented by the composition formula CaCO3 and is the main component of shells, chicken eggshells, limestone, chalk, etc. Calcium carbonate is classified into heavy calcium carbonate (natural calcium carbonate) obtained by pulverizing and classifying limestone and light calcium carbonate (synthetic calcium carbonate) obtained by chemical reaction. The calcium carbonate produced in this embodiment is a kind of light calcium carbonate. When simply referred to as calcium carbonate in this specification, it refers to light calcium carbonate (synthetic calcium carbonate) unless otherwise specified. Calcium carbonate has crystal polymorphs such as calcite crystals (trigonal rhombohedral crystals), aragonite crystals (orthorhombic crystals), and vaterite crystals (hexagonal crystals). However, the calcium carbonate particles used in the embodiment are of the calcite type, and the calcium carbonate granules produced in the embodiment are also of the calcite type.

[0022] Here, the calcium carbonate particles used in the embodiment refer to particles of calcium carbonate and include primary particles, secondary particles formed by aggregation of primary particles, and particles having higher-order structures. The calcium carbonate particles used in the embodiment may have a dense structure (i.e., a structure that is not a hollow structure) or a hollow structure with cavities. In the embodiment, calcite-type calcium carbonate particles refer to primary particles, secondary particles, and higher-order particles of calcium carbonate having the structure of calcite crystals.

[0023] On the other hand, the calcium carbonate granules produced by the production method of the embodiment refer to granules having a relatively uniform particle size of calcium carbonate. The granules are secondary particles or higher-order particles formed by aggregation of primary particles of calcium carbonate and generally have properties such as having pores and being easily disintegrated. The calcite-type calcium carbonate granules produced in the embodiment may have a dense structure (i.e., a structure that is not a hollow structure) or a hollow structure with cavities.

[0024] The manufacturing method of the embodiment includes a step of mixing calcite-type calcium carbonate particles, gelatin, and water, and heating and stirring them to obtain a gelatin / calcite-type calcium carbonate particle mixed slurry A. The calcium carbonate used as a raw material in this step is of the calcite type, and its primary particle size is 10 - 300 nm, preferably 30 - 150 nm, more preferably 50 - 120 nm, and most preferably 80 - 100 nm. The gelatin used in this step is a protein obtained by extracting collagen fibers contained in animal bones and skins with hot water. Gelatin can be used regardless of whether it is derived from cows, pigs, or fish. When calcite-type calcium carbonate particles, gelatin, and water are mixed and stirred at 50 - 60°C, preferably 50 - 55°C, a water slurry in which gelatin and calcite-type calcium carbonate particles are dispersed is obtained. At this time, in the gelatin / calcite-type calcium carbonate particle mixed slurry A, gelatin and calcite-type calcium carbonate are mixed so that the mass ratio of gelatin to calcite-type calcium carbonate particles is in the range of 5:10 - 25:10, more preferably 10:10 - 20:10. If the mass of gelatin relative to the mass of calcite-type calcium carbonate particles is reduced, the calcite-type calcium carbonate granules finally obtained in this embodiment tend to have a dense structure rather than a hollow structure. If the mass of gelatin relative to the mass of calcite-type calcium carbonate particles is increased, the calcite-type calcium carbonate granules finally obtained in this embodiment tend to have a hollow structure. Also, it is preferable to use water in an amount of 2.5 - 6 times, preferably 3 - 4.5 times, the total mass of gelatin and calcite-type calcium carbonate.

[0025] The manufacturing method of the embodiment includes, separately from the step of obtaining the above gelatin / calcite-type calcium carbonate particle mixed slurry A, a step of dissolving a surfactant in oil and stirring to obtain solution B. Any surfactant that can be dissolved in the oil described below may be used. For example, anionic surfactants such as monoalkyl sulfates, alkyl polyoxyethylene sulfates, alkylbenzene sulfonates, and monoalkyl phosphates; cationic surfactants such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkylbenzyldimethylammonium salts; amphoteric surfactants such as alkyl carboxybetaines; and nonionic surfactants such as polyoxyethylene alkyl ethers, fatty acid sorbitan esters, alkyl polyglycosides, fatty acid diethanolamides, and alkyl monoglyceryl ethers can be selected. In particular, it is preferable to use water-soluble nonionic surfactants such as polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monolaurate, known by the name of Tween, and sorbitan monooleate, sorbitan monostearate, sorbitan monopalmitate, sorbitan monolaurate, known by the name of Span. As the oil for dissolving the surfactant, oils that are liquid at room temperature, such as paraffinic base oils, naphthenic base oils, vegetable or animal edible oils, and industrial fats and oils, can be used. In particular, it is preferable to use paraffinic base oils or edible oils. The volume ratio of the surfactant to the oil can be in the range of 1:100 - 5:100, preferably in the range of 1:100 - 2:100.

[0026] After obtaining the gelatin / calcite calcium carbonate particle mixed slurry A and the solution B, the gelatin / calcite calcium carbonate particle mixed slurry A and the solution B are mixed and stirred to obtain an emulsion emulsion C. The volume ratio of the gelatin / calcite calcium carbonate particle mixed slurry A to the solution B is in the range of 1:10 - 10:10, preferably in the range of 1:10 - 2:10. The gelatin / calcite calcium carbonate particle mixed slurry A is added to the solution B and the two are mixed. When mixing the two, the gelatin / calcite calcium carbonate particle mixed slurry A can be added to the solution B at once, or it can be added dropwise while stirring the solution B. Also, the solution B can be added to the gelatin / calcite calcium carbonate particle mixed slurry A at once, or the solution B can be added dropwise while stirring the gelatin / calcite calcium carbonate particle mixed slurry A. Stirring of the mixture of the two can be carried out using an existing stirring device such as a magnetic stirrer, a stirrer equipped with various stirring blades, an ultrasonic stirrer, etc. The stirring speed is preferably, for example, 300 - 1500 rpm, preferably 700 - 1200 rpm. In this way, the emulsion emulsion C is obtained. The emulsion emulsion C is a liquid in a state where particles in which gelatin and calcite calcium carbonate particles are aggregated are emulsified (dispersed) in oil. By appropriately changing the stirring speed in this step, the aggregation form of gelatin and calcite calcium carbonate particles can be changed. Generally, if the stirring speed is slowed down, a structure in which gelatin (hydrophilic part) and calcite calcium carbonate (hydrophobic part) randomly aggregate around a large aggregate of gelatin (hydrophilic part) is likely to form, and the diameter of the aggregate is likely to be relatively large. Also, if the stirring speed is increased, a structure in which gelatin (hydrophilic part) and calcite calcium carbonate (hydrophobic part) randomly aggregate is likely to form, and the diameter of the aggregate is likely to be relatively small.

[0027] Next, a step of adding a crosslinking agent to the emulsion C and stirring to obtain an emulsion D containing gelatin / calcite-type calcium carbonate composite particles is performed. Any compound can be used as the crosslinking agent as long as it can crosslink the gelatin contained in the gelatin / calcite-type calcium carbonate particles emulsified and dispersed in the emulsion D. As the crosslinking agent, for example, 3-ethylcarbodiimide hydrochloride (such as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride), 3-ethylcarbodiimide sulfate (such as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide sulfate), 3-ethylcarbodiimide nitrate (such as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide nitrate), transglutaminase, an olefin-maleic anhydride copolymer, an ammonia reaction product with an ethylenically unsaturated anhydride-maleic anhydride copolymer, a polyamide epoxy resin, glutaraldehyde, or genipin can be used. At this time, the crosslinking agent can be added to the emulsion C so that the mass ratio of gelatin to the crosslinking agent is in the range of 4:1 to 30:1, preferably in the range of 5:1 to 20:1. When the crosslinking agent is added to the emulsion C and stirred, the gelatin in the gelatin / calcite-type calcium carbonate particles is crosslinked to form gelatin / calcite-type calcium carbonate composite particles. That is, the emulsion D is a liquid in which the gelatin / calcite-type calcium carbonate composite particles are emulsified and dispersed in oil.

[0028] Subsequently, a step is performed of centrifuging emulsion D containing gelatin / calcite calcium carbonate composite particles to obtain gelatin / calcite calcium carbonate composite particles. The obtained gelatin / calcite calcium carbonate composite particles are granular solids formed by the composite of cross-linked gelatin and calcite calcium carbonate. For example, they can be composite particles forming a sea-island structure, including an island structure of cross-linked gelatin in the sea structure of calcite calcium carbonate. Also, there may be a case where cross-linked gelatin specifically aggregated in the central part of the gelatin / calcite calcium carbonate composite particles forms a structure in which cross-linked gelatin and calcite calcium carbonate form a sea-island structure around it. The gelatin / calcite calcium carbonate composite particles obtained by centrifugation can be washed with a washing solvent such as water or alcohol and dried as appropriate. The particle diameter of the gelatin / calcite calcium carbonate particles depends on the stirring speed in the step of obtaining emulsion C and the amount of the cross-linking agent, and usually, those in the range of 1 - 500 μm, preferably in the range of 5 - 200 μm are obtained.

[0029] The step of firing the thus obtained gelatin / calcite calcium carbonate composite particles to obtain calcite calcium carbonate granules is carried out. The firing of the gelatin / calcite calcium carbonate composite particles is carried out at a temperature of 430 °C or higher and less than 650 °C, preferably 450 °C or higher and less than 600 °C, in air or under carbon dioxide, or in an inert gas atmosphere such as nitrogen or argon. When firing is carried out in air, the temperature is 530 °C or higher and less than 600 °C, when firing is carried out under carbon dioxide, the temperature is 450 °C or higher and less than 500 °C, and when firing is carried out under an inert gas, the temperature can be 500 °C or higher and less than 600 °C. The firing of the gelatin / calcite calcium carbonate composite particles can be carried out using an existing ceramics firing furnace. When the gelatin / calcite calcium carbonate composite particles are fired, the gelatin part is incinerated (burned), and only the calcite calcium carbonate part remains. That is, among the gelatin / calcite calcium carbonate particles, only the part with the island structure (gelatin) is removed by incineration (burning), and only the part with the sea structure (calcite calcium carbonate) remains, that is, particles with a shape having pores here and there are obtained. Such a shape is referred to as granules in this specification. If the firing temperature is too low, the gelatin part remains in the calcite calcium carbonate granules and is partially carbonized. If the firing temperature is too high, calcium carbonate may partially become calcium oxide and a porous structure may not be obtained. The diameter of the obtained calcite calcium carbonate granules is almost the same as the particle diameter of the gelatin / calcite calcium carbonate particles obtained in the previous step, usually in the range of 1 - 500 μm, preferably 5 - 200 μm, or slightly smaller than the particle diameter of the gelatin / calcite calcium carbonate particles obtained in the previous step. The calcite calcium carbonate granules are almost spherical, but there are cases where those having a large hole (cavity) in the central part (hollow shape) are obtained and cases where those not having a large hole in the central part are obtained.

[0030] The manufacturing method of the embodiment can obtain calcite-type calcium carbonate particles with a high yield through a relatively simple process, so it is suitable for large-scale production of calcite-type calcium carbonate. The obtained calcite-type calcium carbonate particles are porous with pores, and various drugs can be supported in these pores. The calcite-type calcium carbonate produced in the embodiment can be utilized, for example, as a drug delivery system, a catalyst carrier, a cosmetic or toiletry additive, a food additive, a health food, or a daily sundry good.

Examples

[0031] The embodiments of the present invention will be specifically described below. The present invention is not limited to the following examples.

[0032] <Manufacture of Calcite-Type Calcium Carbonate Particles> [Example 1] Gelatin (Fuji Film Wako Pure Chemical Industries, Ltd.) and calcite-type calcium carbonate with a particle diameter of 80 nm (Shiraishi Central Research Institute Co., Ltd.) were dispersed in water so that the mass ratio was 1:1. It was heated to a temperature of 50 - 60 °C and stirred using a stirrer to obtain a gelatin / calcite-type calcium carbonate particle mixed slurry (gelatin / calcite-type calcium carbonate particle mixed slurry A). On the other hand, a surfactant (Span 80, Fuji Film Wako Pure Chemical Industries, Ltd.) and liquid paraffin (Fuji Film Wako Pure Chemical Industries, Ltd.) were mixed so that the volume ratio was 2:100 and stirred to obtain a solution (solution B). Next, the gelatin / calcite-type calcium carbonate particle mixed slurry A was added to solution B so that the volume ratio of the gelatin / calcite-type calcium carbonate particle mixed slurry A to solution B was 2:10, and it was stirred at a stirring speed of 700 rpm at room temperature to obtain an emulsion emulsion (emulsion emulsion C). To emulsion C, a crosslinking agent was added such that the mass ratio of gelatin to the carbodiimide hydrochloride (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, manufactured by Fujifilm Wako Pure Chemical Corporation) as the crosslinking agent was 4:1. When this was stirred, an emulsion (emulsion D) containing gelatin / calcite calcium carbonate particles was obtained. Emulsion D was separated using a centrifuge, and the obtained solid portion was washed 5 times with acetone and dried at room temperature under the atmosphere to obtain gelatin / calcite calcium carbonate composite particles. When the gelatin / calcite calcium carbonate composite particles were calcined at 530 °C under the atmosphere using a firing furnace, porous calcium carbonate granules were obtained.

[0033] Figure 1-A is an electron micrograph (magnification: 500 times) of the calcium carbonate granules obtained by the method of Example 1. In the observation field of view, porous granules having a particle size of about 10 μm - 30 μm were seen. Figure 1-B is an electron micrograph with a magnification of 20,000 times, and it can be observed that there is a pore structure on the surface of the granules. When the calcium carbonate granules obtained in Example 1 were measured for the pore size distribution by the mercury intrusion method (Japanese Industrial Standard JIS 1655:2003), as shown in Figure 2, it was found that pores exist in the calcium carbonate granules. Also, from the crystal structure analysis by X-ray diffraction method, it was found that the calcium carbonate is calcite crystal (Figure 3).

[0034] [Examples 2 - 3] Example 1 was repeated except that the stirring speed of the gelatin / calcite calcium carbonate composite particles was set to 500 rpm. Porous calcite calcium carbonate granules were obtained (Example 2). An electron micrograph (magnification: 500 times) of the calcium carbonate granules obtained in Example 2 is shown in Figure 4. Example 1 was repeated except that the firing temperature of the gelatin / calcite calcium carbonate composite particles was set to 570 °C. Porous calcite calcium carbonate granules were obtained (Example 3).

[0035] [Example 4] Gelatin (FUJIFILM Wako Pure Chemical Corporation) and calcite calcium carbonate with a particle size of 80 nm (Shiraishi Central Research Institute Co., Ltd.) were dispersed in water so that the mass ratio was 2:1. It was heated to a temperature of 50 - 60 °C and stirred using a stirrer to obtain a gelatin / calcite calcium carbonate particle mixed slurry (gelatin / calcite calcium carbonate particle mixed slurry A). On the other hand, a surfactant (Span 80, FUJIFILM Wako Pure Chemical Corporation) and liquid paraffin (FUJIFILM Wako Pure Chemical Corporation) were mixed so that the volume ratio was 1:100 and stirred to obtain a solution (solution B). Solution B was cooled with ice water. Next, the gelatin / calcite calcium carbonate particle mixed slurry A was cooled with ice water and added to solution B cooled with ice water so that the volume ratio of the gelatin / calcite calcium carbonate particle mixed slurry A to solution B was 1:10, and it was stirred at 0 °C and a stirring speed of 1000 rpm to obtain an emulsion emulsion (emulsion emulsion C). To the emulsion emulsion C, a crosslinking agent was added so that the mass ratio of gelatin to carbodiimide hydrochloride (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, FUJIFILM Wako Pure Chemical Corporation) as the crosslinking agent was 10:1. When this was stirred, an emulsion (emulsion D) containing gelatin / calcite calcium carbonate particles was obtained. Emulsion D was separated using a centrifuge, and the obtained solid part was washed 5 times with acetone and dried at room temperature in the air to obtain gelatin / calcite calcium carbonate composite particles. When the gelatin / calcite calcium carbonate composite particles were calcined at 530 °C in the air using a firing furnace, porous calcium carbonate granules having a hollow shape with a hole in the center were obtained.

[0036] Figure 5-A is an electron micrograph (magnification: 500 times) of calcium carbonate particles obtained by the method of Example 4. Partially cracked particles were observed. From this photograph, it was found that the calcium carbonate particles had a hollow structure with a hole in the center. Figure 5-B is an electron micrograph of calcium carbonate particles with a magnification of 20,000 times, similar to Figure 1-B. It can be observed that there is a pore structure on the surface. When the crystal structure analysis of the calcium carbonate particles obtained in Example 4 was performed by X-ray diffraction method, it was found that the calcium carbonate was calcite crystal (Figure 6).

[0037] [Examples 5-7] Example 1 was repeated except that the calcination of gelatin / calcite-type calcium carbonate composite particles was carried out at a temperature of 450 °C under carbon dioxide gas. Porous calcite-type calcium carbonate particles were obtained (Example 5). Example 1 was repeated except that the calcination of gelatin / calcite-type calcium carbonate composite particles was carried out at a temperature of 460 °C under carbon dioxide gas. Porous calcite-type calcium carbonate particles were obtained (Example 6). Example 1 was repeated except that the calcination of gelatin / calcite-type calcium carbonate composite particles was carried out at a temperature of 470 °C under carbon dioxide gas. Porous calcite-type calcium carbonate particles were obtained (Example 7).

[0038] [Example 8] Gelatin (Fuji Film Wako Pure Chemical Corporation) and calcite-type calcium carbonate with a particle diameter of 80 nm (Shiraishi Central Research Institute Co., Ltd.) were dispersed in water so that the mass ratio was 2:1. It was heated to a temperature of 50-60 °C and stirred using a stirrer to obtain a gelatin / calcite-type calcium carbonate particle mixed slurry (gelatin / calcite-type calcium carbonate particle mixed slurry A). On the other hand, a surfactant (Span 80, Fuji Film Wako Pure Chemical Corporation) and liquid paraffin (Fuji Film Wako Pure Chemical Corporation) were mixed so that the volume ratio was 1:100 and stirred to obtain a solution (solution B). Solution B was cooled with ice water. Next, gelatin / calcite calcium carbonate particle mixed slurry A was added to solution B cooled with ice water so that the volume ratio of gelatin / calcite calcium carbonate particle mixed slurry A to solution B was 1:10, and stirred at 0 °C and a stirring speed of 1000 rpm to obtain an emulsion emulsion (emulsion emulsion C). To emulsion emulsion C, a cross-linking agent was added so that the mass ratio of gelatin to carbodiimide hydrochloride (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, Fujifilm Wako Pure Chemical Corporation), which is a cross-linking agent, was 10:1. When this was stirred, an emulsion (emulsion D) containing gelatin / calcite calcium carbonate particles was obtained. Emulsion D was separated using a centrifuge, and the obtained solid portion was washed 5 times with acetone and dried at room temperature under the atmosphere to obtain gelatin / calcite calcium carbonate composite particles. When the gelatin / calcite calcium carbonate composite particles were fired at 450 °C under carbon dioxide gas using a firing furnace, porous calcium carbonate granules having a hollow shape with a hole in the center were obtained.

[0039]

Table 1

[0040]

Table 2

[0041] [Comparative Example] Example 1 was repeated except that the firing temperature of the gelatin / calcite calcium carbonate composite particles was 500 °C. Calcite calcium carbonate granules with residual gelatin carbide were obtained (Comparative Example 1). Example 1 was repeated except that the firing temperature of the gelatin / calcite calcium carbonate composite particles was 650 °C. Dense calcite calcium carbonate granules in which some calcium carbonate had become calcium oxide were obtained (Comparative Example 2). Example 1 was repeated except that the calcination temperature of the gelatin / calcite-type calcium carbonate composite particles was 750°C. Calcium oxide particles were obtained (Comparative Example 3).

[0042] Example 1 was repeated except that the calcination of the gelatin / calcite-type calcium carbonate composite particles was carried out at a temperature of 400°C under carbon dioxide gas. Calcite-type calcium carbonate granules with residual gelatin carbide were obtained (Comparative Example 4). Example 1 was repeated except that the calcination of the gelatin / calcite-type calcium carbonate composite particles was carried out at a temperature of 650°C under carbon dioxide gas. Dense calcite-type calcium carbonate granules in which part of the calcium carbonate had become calcium oxide were obtained (Comparative Example 5). Example 1 was repeated except that the calcination of the gelatin / calcite-type calcium carbonate composite particles was carried out at a temperature of 750°C under carbon dioxide gas. Calcium oxide particles were obtained (Comparative Example 6).

[0043]

Table 3-1

[0044]

Table 3-2

[0045] Using the production method of the present invention, calcite-type calcium carbonate granules could be produced by a relatively simple process. The produced calcite-type calcium carbonate is a porous granule, and various drugs and the like can be supported in the pores. By the production method of the present invention, calcite-type calcium carbonate granules with a cavity in the center can also be produced. The obtained calcite-type calcium carbonate granules can be used for drug delivery systems, cosmetic additives, food additives, health foods, catalyst carriers, and the like.

Claims

1. The following steps: A step of mixing calcite-type calcium carbonate particles, gelatin, and water, heating and stirring to obtain a gelatin / calcite-type calcium carbonate particle mixed slurry A: A step of dissolving a surfactant in oil, stirring to obtain a solution B: A step of mixing the gelatin / calcite-type calcium carbonate particle mixed slurry A and the solution B, stirring to obtain an emulsion emulsion C: A step of adding a crosslinking agent to the emulsion emulsion C, stirring to obtain an emulsion D containing gelatin / calcite-type calcium carbonate composite particles: A step of centrifuging the emulsion D containing gelatin / calcite-type calcium carbonate composite particles to obtain gelatin / calcite-type calcium carbonate composite particles; and A step of firing the gelatin / calcite-type calcium carbonate composite particles to obtain calcite-type calcium carbonate granules A method for producing calcite-type calcium carbonate granules, comprising:

2. The method for producing calcite-type calcium carbonate granules according to claim 1, wherein in the gelatin / calcite-type calcium carbonate particle mixed slurry A, the mass ratio of gelatin to calcite-type calcium carbonate particles is in the range of 5:10 - 25:

10.

3. The method for producing calcite-type calcium carbonate granules according to claim 2, wherein in the solution B, the volume ratio of the surfactant to the oil is in the range of 1:100 - 5:

100.

4. The method for producing calcite-type calcium carbonate granules according to claim 2, wherein the volume ratio of the gelatin / calcite-type calcium carbonate particle mixed slurry A to the solution B is in the range of 1:10 - 10:

10.

5. The method for producing calcite-type calcium carbonate granules according to claim 3, wherein the volume ratio of the gelatin / calcite-type calcium carbonate particle mixed slurry A to the solution B is in the range of 1:10 - 10:

10.

6. The method for producing calcite-type calcium carbonate granules according to claim 2, wherein a crosslinking agent is added to the emulsion emulsion C such that the mass ratio of gelatin to the crosslinking agent is in the range of 4:1 - 30:

1.

7. The method for producing calcite-type calcium carbonate granules according to claim 3, wherein a crosslinking agent is added to the emulsion emulsion C such that the mass ratio of gelatin to the crosslinking agent is in the range of 4:1 - 30:

1.

8. The method for producing calcite-type calcium carbonate granules according to claim 4, wherein a crosslinking agent is added to the emulsion emulsion C such that the mass ratio of gelatin to the crosslinking agent is in the range of 4:1 - 30:

1.

9. The method for producing calcite-type calcium carbonate particles according to claim 5, wherein a crosslinking agent is added to the emulsion emulsion C such that the mass ratio of gelatin to the crosslinking agent is in the range of 4:1 to 30:

1.

10. The method for producing calcite-type calcium carbonate particles according to any one of claims 1 to 9, wherein the gelatin / calcite-type calcium carbonate composite particles are calcined at a temperature of 530 °C or higher and lower than 650 °C.

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