JPH11171514A - Hollow fine calcium phosphate particles and their production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain hollow fine calcium phosphate particles almost free from secondary aggregation, having good dispersibility and uniformity and capable of modifying the particle diameter and particle shape by adding an aq. soln. of water-soluble phosphoric acid or its water-soluble salt or the like to a methanolic-aq. suspension of vaterite type calcium carbonate and bringing them into reaction in a neutral region. SOLUTION: At least one selected from among aq. solns., aq. suspensions and methanolic suspensions of water-soluble phosphoric acid and its water-soluble salt, an aq.-methanolic soln. of water-soluble phosphoric acid and an aq.- methanolic suspension of a water-soluble slat of water-soluble phosphoric acid is added to a methanolic-aq. suspension of vaterite type calcium carbonate contg. <=40 wt.% water, a pH adjusting agent is also added and they are brought into reaction in a neutral region at 10-70 deg.C under atmospheric pressure or elevated pressure to obtain the objective hollow fine calcium phosphate particles. The amt. of calcium phosphate in the particles is 2.5-15 wt.%. Hydroxyapatite is particularly preferable as the calcium phosphate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel calcium phosphate fine particle having a hollow structure and a method for producing the same. More specifically, the present invention relates to a fine particle having little secondary aggregation and good dispersibility.
The present invention relates to a hollow calcium phosphate fine particle having a very uniform particle diameter, and a method for industrially and advantageously producing the hollow fine particle at low cost. The hollow fine particles of the present invention include, for example, a catalyst carrier, a pharmaceutical carrier, a pesticide carrier, a microorganism carrier, a biological carrier, a peroxide carrier, a plant growth agent, an olefin absorber, an ultraviolet absorber, an adsorbent, a sustained-release body, and a liquid absorbing agent. , Ceramic raw materials, various carriers, filtration agents, filtration aids, molding aids, breeding microorganisms, biomaterials, desiccants, fragrances, other carriers or their raw materials, plastics, rubber, paints, inks, sealing materials, papermaking, etc. It is useful as a filler, an antiblocking agent for fibers and films, and the like. Further, by combining the above various applications, further new and wide applications can be developed.

[0002]

2. Description of the Related Art It has long been known that calcium phosphate exists in living bodies, and it is, for example, the main composition of bone and teeth. For this reason, in recent years, attention has been paid to the raw materials for bioceramics, and various researches have been conducted, and they are industrially manufactured and sold as food additives, polymerization stabilizers, catalysts, and the like. Also, the physical properties of calcium phosphate greatly affect the particle morphology, and the difference in the particle morphology significantly affects the performance as a material. Therefore, preparation of calcium phosphate having an appropriate particle morphology according to the application is an urgent issue. Japanese Patent Application Laid-Open No. 63-198970 discloses a hollow body of calcium phosphate and a method for producing the same.
A method of firing at 0 to 1400 ° C. is described. However, the particle size described in the publication is 30 to 25.
0 μm, opening diameter 10-40 μm, total pore surface area 6-1
It is 4.4 m ² / g, and its production is not always easy, and the use of the obtained hollow particles has its own limits.

[0003]

As described above, it is difficult to control the particle diameter, dispersion state, particle shape, and the like of the conventional hollow fine particles of calcium phosphate. It is hard to say. Therefore,
There is a demand for hollow-structured calcium phosphate microparticles that can control the particle diameter, particle shape, and the like, and satisfy both high dispersibility and uniformity, and an inexpensive and easy production method thereof.

[0004]

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, the present inventors have found that there is almost no secondary agglomeration, the dispersibility and the uniformity are good, and the particle diameter and the particle shape are adjusted. The present inventors have found possible hollow structure fine particles and an inexpensive and easy production method thereof, and have completed the present invention based on this finding.

That is, a first aspect of the present invention is to provide the following formulas (a) to (a).
A hollow-structure calcium phosphate fine particle characterized by comprising vaterite-type calcium carbonate satisfying (d) as a core material, calcium phosphate being 2.5% by weight to 15% by weight, and further satisfying the following formula (e): And (A) 0.05 ≦ DS ≦ 2.0 (μm) (b) DP3 / DS ≦ 1.25 (c) 1.0 ≦ DP2 / DP4 ≦ 2.5 (d) 1.0 ≦ DP1 / DP5 ≦ 4.0 (e) 0.8 ≦ dx1 / DS ≦ 1.5 where DS is an average particle diameter (μm) measured by a scanning microscope (SEM), and the primary particles are converted into spheres having the same volume. What calculated and calculated the average value of the particle diameter of a sphere DP1: In the particle size distribution measured using the light transmission type particle size distribution measuring device (SA-CP3 made by Shimadzu Corporation),
Particle size (μm) at a cumulative weight of 10% calculated from the larger particle side DP2: Particle size (μm) at a cumulative weight of 25% calculated from the larger particle side in the particle size distribution measured using the above measuring instrument. DP3: In the particle size distribution measured using the above measuring device, the particle size (μm) at 50% of the cumulative weight calculated from the larger particle side. DP4: In the particle size distribution measured using the above measuring device, from the larger particle side. Particle size (μm) at 75% of the cumulative weight calculated DP5: Particle size (μm) at 90% of the cumulative weight calculated from the larger particle side in the particle size distribution measured using the above measuring instrument dx1: Scanning electron Average particle diameter (μm) of hollow structure fine particles measured by microscope (SEM)

A second aspect of the present invention is to provide a vaterite-type calcium carbonate-methanol-water suspension containing 40% by weight or less of water, an aqueous solution of water-soluble phosphoric acid or a water-soluble salt thereof, an aqueous suspension,
In a neutral region, a methanol suspension, a water-soluble phosphoric acid in water-methanol solution, and a water-methanol suspension of a water-soluble salt of water-soluble phosphoric acid are added and a pH adjuster is added. A process for producing fine particles of calcium phosphate having a hollow structure, which comprises reacting at a temperature of 10 to 70 ° C. under normal pressure or pressure, is described.

An important feature of the present invention is that the amount of calcium phosphate is 2.5% by weight while maintaining the particle size, particle shape and dispersibility of vaterite-type calcium carbonate as a core material.
Since the fine particles have a hollow structure content of about 15% by weight, the secondary structure has almost no secondary agglomeration, has good dispersibility, and has a uniform particle diameter. Hereinafter, the present invention will be described in detail.

[0008] The definition of the dispersibility of the vaterite-type calcium carbonate, which is the core material of the hollow fine particles of the present invention, is determined by the formula (a) to
(D). (A) 0.05 ≦ DS ≦ 2.0 (μm) (b) DP3 / DS ≦ 1.25 (c) 1.0 ≦ DP2 / DP4 ≦ 2.5 (d) 1.0 ≦ DP1 / DP5 ≦ 4.0

If the DS of the above (a) is less than 0.05, the dispersibility decreases due to the aggregation of the particles, and if it exceeds 2.0, the particle strength becomes weak, and the DP3 / DS of the above (b) becomes 1.2.
If it exceeds 5, it cannot be said that the dispersion is monodisperse.
When 2 / DP4 exceeds 2.5, the ratio of fine particles and coarse particles increases. DP1 / DP5 of the above (d) is 4.0.
If the ratio exceeds the range, the ratio of fine particles and coarse particles increases.

The calcium phosphate constituting the hollow fine particles of the present invention is not particularly limited, but amorphous calcium phosphate [abbreviation ACP, chemical formula Ca ₃ (PO ₄ ) ₂ .nH _2]
O], fluorapatite [abbreviation FAP, chemical formula Ca
₁₀ (PO ₄ ) ₆ F ₂ ], chlorapatite [abbreviation CAP,
Chemical formula Ca ₁₀ (PO ₄ ) ₆ Cl ₂ ], hydroxyapatite [abbreviation HAP, chemical formula Ca ₁₀ (PO ₄ ) ₆ (OH)
₂ ], octacalcium phosphate [abbreviation OCP, chemical formula Ca _{8
H 2 (PO 4) 6 ·} 5H 2 O ], tricalcium phosphate [Symbol TCP, chemical formula Ca ₃ (PO _{4) 2],} calcium hydrogen phosphate (abbreviation DCP, formula CaHPO _4), calcium hydrogen phosphate dihydrate Japanese (abbreviation DCPD, chemical formula C
aHPO ₄ .2H ₂ O) and the like, and these may be used alone or in combination of two or more. Among them, hydroxyapatite, octacalcium phosphate, tricalcium phosphate, and calcium hydrogenphosphate are preferred, and hydroxyapatite is particularly preferred, from the viewpoint of high composition stability. Also,
With respect to the content of hydroxyapatite having the highest stability, the content is preferably 5% by weight or more, more preferably 50% by weight or more, and most preferably 90% by weight or more of the total calcium phosphate compound.

The amount of calcium phosphate occupying in the hollow fine particles of the present invention is from 2.5% by weight to 15% by weight. If it is less than 2.5% by weight, no hollow particles are produced, and if it exceeds 15% by weight, petal-like particles are produced on the surface of the hollow particles to increase the particle size.

The expansion coefficient dx1 / of the hollow fine particles of the present invention is as follows.
DS is (e) 0.8 ≦ dx1 / DS ≦ 1.5.
If it is less than 0.8, it is difficult to form a hollow structure, and if it exceeds 1.5, it does not have a hollow structure.

The average particle size dx of the hollow fine particles of the present invention
1 is not particularly limited, but if it is less than 0.04 μm, the dispersibility decreases due to aggregation of the particles, and if it exceeds 3.0, the particle strength becomes weak. Therefore, (f) 0.04 ≦ dx
1 ≦ 3.0.

The dispersion coefficient d50 of the hollow fine particles of the present invention
The ratio / dx1 is not particularly limited, but if the dispersion coefficient exceeds 1.25, the ratio of coarse aggregates increases, and if it is less than 1, the ratio of fine particles increases, and the cohesiveness of the particles increases. (G) 1 ≦ d50 / dx1 ≦ 1.2
5 Sharpness (d10-d90) / d5
0 is not particularly limited, but if it exceeds 3, the particle diameter is non-uniform or coarse aggregates are mixed. Therefore, it is preferable that (h) 0 ≦ (d10−d90) / d50 ≦ 3.

[0015] The calcium phosphate fine particles having a hollow structure according to the present invention are prepared by adding a water-soluble phosphoric acid, an aqueous solution of a water-soluble salt of water-soluble phosphoric acid, and a water suspension to a vaterite-type calcium carbonate-methanol-water suspension containing 40% by weight or less of water. At least one selected from a suspension, a methanol suspension, a water-methanol solution of water-soluble phosphoric acid, and a water-methanol suspension of a water-soluble salt of water-soluble phosphoric acid is added, and a pH adjuster is added. It can be produced by reacting at a temperature of 10 to 70 ° C. under normal pressure or pressure in the region.

The reaction system is a methanol-water system, and the amount of water in the vaterite-type calcium carbonate-methanol-water suspension is 40% by weight or less. If the amount of water exceeds 40% by weight, vaterite-type calcium carbonate is undesirably transferred to calcite-type calcium carbonate. The pH during the reaction is in the neutral region (pH 6 to 8). When the pH is lower than 6 or higher than 8, hydroxyapatite is hardly generated, and good hollow particles are not formed. Furthermore,
The reaction temperature is from 10 to 70C. When the temperature is lower than 10 ° C. or higher than 70 ° C., hydroxyapatite is hardly generated, and good hollow particles are not formed. Further, the pH adjuster is not particularly limited, and examples thereof include calcium chloride and sodium hydroxide, and these may be used alone or in combination of two or more.

In a preferred method for producing the hollow-structure calcium phosphate of the present invention, for example, the average particle size measured by a light transmission type particle size distribution analyzer (SA-CP3 manufactured by Shimadzu Corporation) is 0.05 to 2.0 μm. Water-methanol mixed suspension of vaterite-type calcium carbonate, and diluted water-methanol mixed solution of phosphoric acid, suspension of calcium dihydrogen phosphate having an average particle diameter of 2 to 10 μm measured by the above measuring instrument, or The proportion of one or more selected from calcium hydrogen phosphate dihydrate suspensions having an average particle diameter of 2 to 10 μm measured by the above-mentioned measuring device in the particle weight of calcium phosphate is 2.5% by weight or more. 15% by weight, and the mixture was reacted under the following reaction conditions, then aged under the following aging conditions, and then dehydrated or without dehydration燥後, perform a crushing finish.

Reaction conditions: Vaterite-type calcium carbonate in water-methanol suspension solids concentration 1 to 15% by weight Phosphoric acid diluent concentration 1 to 50% by weight Suspension solids concentration in calcium dihydrogen phosphate 2 15% by weight calcium hydrogen phosphate dihydrate suspension solids concentration 2 to 15% by weight Reaction time 0.1 to 150 hours Reaction suspension temperature 10 to 70 Reaction suspension pH 6 to 8

Ripening conditions: Ripening temperature 0.1-100 hours Ripening suspension temperature 10-80 ° C. Ripening suspension pH 6-8

The hollow-structure calcium phosphate fine particles of the present invention may further contain a coupling agent such as a silane coupling agent or a titanate coupling agent, a fatty acid, a resin acid, an acrylic acid, a sulfuric acid, etc., in order to further enhance the dispersibility and stability of the particles. Acids, citric acid, organic acids such as tartaric acid, inorganic acids such as hydrofluoric acid,
Surface treatment agents such as their polymers and copolymers, their salts, or their esters, surfactants, sodium hexametaphosphate, pyrophosphate, sodium pyrophosphate, tripolyphosphate, sodium tripolyphosphate, trimetaphosphate, high polyphosphate Condensed phosphoric acid such as an acid or a salt thereof may be added or surface treated according to a conventional method.

[0021]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it departs from the gist thereof.

Reference Example Vaterite-type calcium carbonate particles A were prepared by the following method. A quicklime-methanol slurry having a concentration of 10% by weight was diluted to a concentration of 3.5% by weight with an aqueous solution of 94.8% by weight methanol (a first-class reagent manufactured by Nacalai Tesque, Inc.) to perform a digestion reaction for about 20 minutes. Thereafter, carbon dioxide gas was blown in at a flow rate of 1 l / min while stirring in a high-temperature layer maintained at 40 ° C. to carry out a carbonic acid reaction to prepare a slurry of vaterite-type calcium carbonate particles A. The water content of the particle A slurry was 20.4% by weight (Karl Fischer moisture meter,
Measured by Kyoto Electronics Manufacturing Co., Ltd.). Table 1 shows the physical properties of the obtained particles A. Further, a transmission electron microscope (TEM) photograph (magnification: 50,000) showing the particle structure of particle A
Is shown in FIG.

[0023]

[Table 1]

Examples 1 and 2 500 g of a slurry of particles A having a concentration of 3.5% by weight was stirred at 19 ° C. in a reaction vessel, and methanol having a concentration of 2% by weight (special grade reagent manufactured by Nacalai Tesque Co., Ltd.) Aqueous solution 29
4 g was dropped at a rate of about 3 ml / min.
l ₂ · 2H ₂ O (Nacalai Tesque Co., Ltd. first class reagent)
The pH of the reaction solution was adjusted to 7 by adjusting the amount of a slurry in which 0.22 mol of NaOH (special grade reagent manufactured by Nacalai Tesque, Inc.) and 0.11 mol of NaOH were dissolved in 0.7 L of a 94.8% by weight methanol-water solution. And calcium phosphate particles B and C were obtained. The obtained particles B and C had a phosphoric acid dripping amount of 6.2 mmol and 12.4, respectively.
mmol. Next, after further aging under the following aging conditions, dehydration, drying and crushing were performed. Aging time 2 hours Aging suspension temperature 40 ° C Aging suspension pH 7 Table 2 shows the physical properties of the prepared calcium phosphate particles B and C. 2 and 3 show transmission electron micrographs (magnification: 50000) showing the particle structures of the particles B and C, and FIG. 4 shows transmission electron micrographs (magnification: 75000) showing the cross section of the particle B.

From FIGS. 2, 3 and 4, it can be confirmed that the particles B and C have a hollow structure. Table 3 shows the results of the component analysis of the particles B. The inner composition (Ca / P) of the calcium phosphate forming the outer layer was considerably large at 4.68, but the surface composition was close to the hydroxyapatite composition. No change was observed in the particle diameter before and after the reaction.

Comparative Examples 1 and 2 Calcium phosphate particles D and E were obtained in the same manner as in Example 1 except that the amount of phosphoric acid dropped was changed. Particles D and E have dropping amounts of phosphoric acid of 2.1 mmol and 18.8 mmol, respectively. Table 2 shows the physical properties of the prepared particles D and E. Also, particles D,
E micrograph (50,000) showing the particle structure of E
5) are shown in FIGS. From FIG. 5, it can be confirmed that although the particle diameter of the particle D does not change, a hollow structure is not formed. In addition, it can be confirmed from FIG. 6 that the particle E does not have a hollow structure, but has a distorted surface on the particle, and does not maintain the shape of the core material vaterite-type calcium carbonate.

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

As described above, since the calcium phosphate fine particles of the present invention have a hollow structure, for example, a catalyst carrier, a pharmaceutical carrier, a pesticide carrier, a microorganism carrier, a biological carrier, a peroxide carrier, a plant growth agent, an olefin absorber , UV absorbers, adsorbents, sustained-release bodies, liquid absorbing agents, ceramic raw materials, various carriers, filtering agents, filter aids, molding aids, breeding microorganisms, biomaterials, desiccants, fragrances, other carriers or their raw materials Useful. In addition, plastic, rubber, paint, ink,
It is also useful as a filler for sealing materials and papermaking, as an anti-blocking agent for fibers and films, and has the advantage of being particularly self-disintegrating and lightweight.

[Brief description of the drawings]

FIG. 1 is a transmission electron micrograph (magnification: 50,000) showing the particle structure of vaterite-type calcium carbonate particles A.

FIG. 2 is a transmission electron micrograph (50000 times) showing the particle structure of calcium phosphate particles B.

FIG. 3 is a transmission electron micrograph (magnification: 50,000) showing the particle structure of calcium phosphate particles C.

FIG. 4 is a transmission electron micrograph (magnification: 75,000) showing the particle structure of a cross section of calcium phosphate particles B.

FIG. 5 is a transmission electron micrograph (magnification: 50,000) showing the particle structure of calcium phosphate particles D.

FIG. 6 is a transmission electron micrograph (magnification: 50,000) showing the particle structure of calcium phosphate particles E.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsunobu Aoyama 1653-105 Nishioka, Uozumi-cho, Akashi-shi, Hyogo

Claims (4)

[Claims] 1. A vaterite-type calcium carbonate satisfying the following formulas (a) to (d) is used as a core material, and calcium phosphate is 2.5 to 15% by weight, and further satisfies the following formula (e). Calcium phosphate fine particles having a hollow structure. (A) 0.05 ≦ DS ≦ 2.0 (μm) (b) DP3 / DS ≦ 1.25 (c) 1.0 ≦ DP2 / DP4 ≦ 2.5 (d) 1.0 ≦ DP1 / DP5 ≦ 4.0 (e) 0.8 ≦ dx1 / DS ≦ 1.5 where DS is an average particle diameter (μm) measured by a scanning microscope (SEM), and the primary particles are converted into spheres having the same volume. What calculated and calculated the average value of the particle diameter of a sphere DP1: In the particle size distribution measured using the light transmission type particle size distribution measuring device (SA-CP3 made by Shimadzu Corporation),
Particle size at the time of 10% of weight accumulation calculated from the larger particle side (μm) DP2: Particle size at the time of 25% of weight accumulation calculated from the larger particle side (μm) in the particle size distribution measured using the above measuring instrument. DP3: In the particle size distribution measured using the above measuring device, the particle size (μm) at 50% of the cumulative weight calculated from the larger particle side. DP4: In the particle size distribution measured using the above measuring device, from the larger particle side. Particle size (μm) at 75% of the cumulative weight calculated DP5: Particle size (μm) at 90% of the cumulative weight calculated from the larger particle side in the particle size distribution measured using the above measuring instrument dx1: Scanning electron Average particle diameter (μm) of hollow structure fine particles measured by microscope (SEM) 2. The fine particles of calcium phosphate having a hollow structure according to claim 1, further satisfying the following expressions (f) to (h). (F) 0.04 ≦ dx1 ≦ 3.0 (μm) (g) 1 ≦ d50 / dx1 ≦ 1.25 (h) 0 ≦ (d10−d90) / d50 ≦ 3 dx1: Same as above d50: Light transmission In the particle size distribution measured using a particle size distribution analyzer (SA-CP3 manufactured by Shimadzu Corporation),
Particle size (μm) of hollow structure fine particles at a cumulative weight of 50% calculated from the large particle side d90: In the particle size distribution measured using the above measuring device, hollow at a cumulative weight of 90% calculated from the large particle side Particle size (μm) of structural fine particles d10: Particle size (μm) of hollow structural fine particles at a cumulative weight of 10% calculated from the larger particle side in the particle size distribution measured using the above measuring instrument. 3. The hollow calcium phosphate fine particles according to claim 1, wherein the calcium phosphate is hydroxyapatite. 4. A vaterite-type calcium carbonate-methanol-water suspension containing 40% by weight or less of water is added to an aqueous solution of water-soluble phosphoric acid or a water-soluble salt thereof, an aqueous suspension, a methanol suspension, or a water-soluble solution. At least one selected from a water-methanol solution of phosphoric acid and a water-methanol suspension of a water-soluble salt of water-soluble phosphoric acid is added, and a pH adjuster is added. A method for producing fine particles of calcium phosphate having a hollow structure, wherein the reaction is carried out at a temperature of 70 ° C.