JPH1036106A - Porous bulk apatite carbonate and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a porous bulk apatite carbonate with a simple procedure free from the troubles of conventional production process by reacting a composition containing calcium carbonate with phosphoric acid under specific condition. SOLUTION: This porous bulk apatite carbonate contains >=0.5wt.% of calcium carbonate and has a BET specific surface area of >=10m<2> /g. The porous bulk apatite carbonate can be produced by reacting a substance containing calcium carbonate with phosphoric acid in a neutral region. The calcium carbonate-containing substance to be used as a raw material is preferably a natural material, especially shell. The average particle diameter of the porous bulk apatite carbonate can be controlled within the range of 1-50μm by controlling the average particle diameter of the substance containing calcium carbonate to 0.5-20μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention is useful as a material for biological implant materials such as artificial bones and artificial teeth, as well as materials for toothpastes, fragrance carriers, antibacterial agents, adsorbents, and adhesive compositions. The present invention relates to a porous massive apatite and a method for producing the porous massive apatite.

[0002]

BACKGROUND ART carbonated apatite, i.e. apatite containing carbonate groups has the formula _{Ca 10 (PO 4) 6 (} OH) 2 hydroxyl groups ^- substituted in some carbonate group (CO ₃ ^2-) (OH) Type A and type B in which a part of a phosphoric acid group (PO ₄ ^3- ) is substituted with a carbonic acid group are known. This carbonate apatite has a hydroxyapatite (H
AP) and tricalcium phosphate are used as materials closer to the bones and teeth that make up the human body as compared to tricalcium phosphate, and are used as materials for biological implant materials such as artificial bones and artificial teeth. It is used as a material for fragrance carriers, antibacterial agents, and adsorbents. Furthermore, as a new application in recent years, it has been used as an additive for an adhesive composition (for example, see JP-A-5-78632 and JP-A-4-78632).
No. 106177).

[0003] In producing carbonated apatite,
A dry method, a wet method, and the like are known, but a wet method is widely used because it has a property of being excellent in low-temperature sinterability when producing a biological implant material by sintering a carbonate apatite powder. As a typical production method in this wet method, a calcium salt and phosphoric acid (or a phosphate) are generally reacted in an aqueous solution (for example, see JP-A-5-7).
8632, JP-A-4-106177, etc.). However, the carbonate apatite obtained by these methods has a limited particle size and carbonic acid content depending on the production method. In addition, since the reaction is carried out under basic conditions in the above wet method, there is a possibility that an alkaline substance such as calcium hydroxide may remain in the obtained carbonate apatite.

[0004] For these reasons, there has been proposed a method of producing carbonic apatite by introducing carbon dioxide gas into a synthesis system and reacting it in a neutral region. However, such a method requires an airtight reaction vessel capable of sealing the gas, and uses a variety of buffers to adjust the pH to a neutral range. Therefore, it is necessary to remove the used buffers and generated by-products. There is.

On the other hand, various techniques have been proposed for effectively utilizing calcium carbonate-containing natural resources that have not been used so far, such as shells, fish scales, fish and animal bones, as raw materials for producing apatite (see, for example, US Pat. For example, JP
3-107807, JP-A-7-303889, JP-A-7-277712, JP-A-8-104508, and the like. However, in these methods, the treatment is basically performed in the same manner as in the above-mentioned wet method, and the above-mentioned problems remain.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made under such circumstances, and has as its object the purpose of artificial bones and artificial teeth, toothpaste bases, fragrance carriers, antibacterial agents, adsorbents and the like. An object of the present invention is to provide a method for producing carbonate apatite useful as a raw material by a simple procedure without causing problems in the prior art, and to provide a carbonate apatite thus produced.

[0007]

Means for Solving the Problems The present invention which has solved the above-mentioned problems has a gist in that it contains calcium carbonate in an amount of 0.5% by weight or more and a BET specific surface area is 10m ² / g or more. It is a porous massive carbonate apatite.

The above-mentioned porous massive carbonate apatite of the present invention can be produced by using calcium carbonate-containing material and reacting with phosphoric acid in a neutral region. The calcium carbonate-containing material as a raw material is preferably a natural product, and among them, a shell is most preferable.

The object of the present invention can be achieved by using the calcium carbonate-containing material having an average particle size of 0.5 to 1000 μm. It is useful to control the average particle diameter of the porous massive carbonate apatite within the range of 1 to 50 μm when the thickness is controlled to 20 μm.

Further, by controlling the reaction rate,
Formula _{Ca 10 (PO 4) 6 (} OH) in the apatite represented by ₂ (PO ₄ ^3-) in the range of 0.01 to 1 mol (CO
₃ ^2- ) can be substituted.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have studied from various angles in order to achieve the above object. As a result, if the calcium carbonate-containing substance and phosphoric acid are reacted in a neutral region, the reaction can be effectively advanced without adding a treatment with an acid or an alkali, and without using various buffers. Thus, the present inventors have found that a porous massive carbonate apatite having desired properties can be obtained, and have completed the present invention.
It has also been found that the method of the present invention has the following advantages (1) and (2).

(1) By controlling the average particle diameter of the raw material calcium carbonate to 0.5 to 20 μm, the average particle diameter of the porous massive carbonate apatite can be controlled within the range of 1 to 50 μm. (2) By controlling the reaction rate, the chemical formula Ca ₁₀
(PO ₄ ) ₆ (OH) _{2 In} the apatite represented by (PO
₄ ³⁾ can be replaced by a range of 0.01~1mol (CO ₃ ^2-).

The method of the present invention is most characterized by reacting the calcium carbonate-containing substance with phosphoric acid in a neutral region. Although I was not able to elucidate, it can probably be considered as follows. That is, the phosphoric acid dropped into the calcium carbonate slurry first reacts on the surface to generate apatite. Then, the phosphoric acid that is sequentially dropped reacts with calcium carbonate eluted from the inside that has become porous, and further grows apatite toward the outside. At this time, it is considered that (CO ₃ ^2- ) generated by the decomposition of calcium carbonate exists near the growth point of apatite, and during the crystal growth, it is competitively substituted with (PO ₄ ^3- ) to generate carbonate apatite. Can be

In the present invention, "reacting in a neutral range" means that most of the reaction proceeds in a neutral range of about pH 6.0 to 7.0. This also includes the case where the pH sharply drops to the acidic side of about 5 at the time of completion (see Examples described later).

As the calcium carbonate-containing substance used as a raw material in the present invention, pulverized calcium carbonate excavated as ore (for example, calcium carbonate manufactured by Calceed Inc., calcium carbonate manufactured by Bihoku Powder Chemical Industry Co., Ltd.) can also be used. However, it is preferable to use those obtained by crushing natural calcium carbonate-containing substances such as animal bones and shells. Among them, industrial raw materials include shells in view of availability in large quantities and purity. Is the most preferable. These calcium carbonate-containing substances can be used alone or as a mixture. In addition, as the bones of the above-mentioned animals, mollusks such as squid, coelenterates such as creatures,
Any of vertebrates such as cows may be used.

The above-mentioned ground calcium carbonate-containing material preferably has a particle size of 0.5 μm or more in consideration of reactivity. If the particle size is less than 0.5 μm, the cost of pulverizing the raw material becomes high, Is too fast to control, and may generate calcium hydrogen phosphate or the like. On the other hand, the upper limit of the particle size of the calcium carbonate-containing material is preferably 20 μm or less from the viewpoint that the average particle size of the porous massive carbonate apatite can be controlled within the range of 1 to 50 μm. The following can also be used: The calcium carbonate-containing material is suspended in water at a ratio of, for example, 1 to 30% to form a suspension (reaction liquid slurry), and a phosphoric acid diluent (preferably, about 10 to 80%) is mixed with the suspension. By reacting at about 30 to 100 ° C. for 1 to 10 hours, the porous massive carbonate apatite of the present invention can be obtained.

It is considered that the porous massive carbonate apatite obtained as described above has a substantially two-layer structure in which most of calcium carbonate (that is, unreacted calcium carbonate-containing material) is unevenly distributed in the center. . That is, in the method of the present invention,
The reaction proceeds from the periphery of the calcium carbonate-containing material, and finally becomes a porous massive carbonate apatite having a substantially two-layer structure with calcium carbonate remaining in the center. Then, the content including the unevenly distributed portion of calcium carbonate is approximately 0.5% by weight or more.

On the other hand, particle morphology and BET ratio
It is known that the surface area is correlated, for example,
BET specific surface area of whiskers and agglomerates is 1
0m ^Two / G or more, and 10 m for fine granules^Two /
g. That is, in the conventional manufacturing method, fine (immediate)
That is, the specific surface area is large, or the fine particles (that is, the specific surface area is large).
Small) Only those having some particle characteristics were obtained. Against this
The carbonate apatite powder according to the present invention has a BET specific surface
Product is 10m^Two / G or more and large porous fine granules
You.

By the way, some shells having a pharmacological effect are also known. For example, the shell of oysters is called borei, and the powder is used as a medicine for Kampo prescription. The carbonate apatite obtained according to the present invention has a substantially two-layer structure in which unreacted calcium carbonate-containing material is unevenly distributed in the center. Therefore, if a shell having a pharmacological effect is used as the calcium carbonate-containing material, the resulting carbonate can be obtained. Apatite can also be expected to have such pharmacological effects depending on its use form. Next, examples will be described.

[0020]

【Example】

Example 1 Under the following conditions, carbonate apatite of the present invention was produced. Reaction vessel: 3 liter stainless steel beaker Raw material: oyster shell powder (average particle diameter: 9.1 μm) Reaction liquid slurry: 200 g of raw material + 1800 ion-exchanged water
g (slurry concentration: 10%) Phosphoric acid (H ₃ PO ₄ ) solution: 30% by weight concentration, 353 g Reaction temperature: 70 ° C. Total dropping time of phosphoric acid: 5 hours (the reaction is completed upon completion of dropping) Final pH: 5. 0 BET specific surface area comparison of the obtained carbonate apatite particles,
It was 23 m ² / g as measured by “BELSORP 28” (manufactured by Nippon Bell Co., Ltd.). X-ray diffraction of the carbonate apatite particles was performed under the following conditions. (X-ray diffraction conditions) X-ray diffraction analyzer: "RAD-1A" (manufactured by Rigaku Corporation) Measurement voltage: 35 KV Measurement current: 15 mA Sensitivity: 2000 cps Time constant: 1 sec Scanning speed: 2 ° / min

FIG. 1 shows the results of X-ray diffraction. FIG. 2 (micrograph as a substitute for a drawing) shows the crystal structure of the obtained carbonate apatite. From these, the following can be considered. In FIG. 1, the portion indicated by an arrow (↓) indicates calcium carbonate. From the peak intensity of the calcium carbonate portion, it could be determined that calcium carbonate in carbonate apatite was 10%.

Examples 2 to 4 The carbonate apatite of the present invention was produced under the following conditions.
In Examples 2 to 4 below, the reaction rate was changed by changing the total time required for dropping phosphoric acid, the reaction concentration, and the reaction temperature.

Example 2 Reactor: 3 liter stainless steel beaker Raw material: Calcium carbonate (manufactured by Calseed Co., Ltd.) is pulverized by a ball mill Raw material average particle diameter: 0.8 μm Reaction liquid slurry: 600 g of raw material + 1400 ion-exchanged water
g (slurry concentration: 30%) Phosphoric acid (H ₃ PO ₄ ) solution: 50% by weight, 351 g Reaction temperature: 60 ° C. Total dropping time of phosphoric acid: 1 hour (reaction is completed upon completion of dropping) Final pH: 5. 1

Example 3 Reaction vessel: 3 liter stainless steel beaker Raw material: clamshell powder Raw material average particle size: 5.3 μm Reaction liquid slurry: 400 g of raw material + 1400 ion-exchanged water
g (slurry concentration: 20%) Phosphoric acid (H ₃ PO ₄ ) solution: 70% by weight concentration, 312 g Reaction temperature: 70 ° C. Total dropping time of phosphoric acid: 5 hours (reaction is completed upon completion of dropping) Final pH: 5. 0

Example 4 Reaction vessel: 5-liter stainless steel beaker Raw material: calcium carbonate (manufactured by Taihei Chemical Industry Co., Ltd.) Average particle diameter: 12.8 μm Reaction liquid slurry: 150 g of raw material + 2850 ion-exchanged water
g (slurry concentration: 5%) Phosphoric acid (H ₃ PO ₄ ) solution: 20% by weight concentration, 398 g Reaction temperature: 90 ° C. Total dropping time of phosphoric acid: 10 hours (reaction is completed upon completion of dropping) Final pH: 5. 2

The obtained carbonate apatite particles were subjected to X-ray diffraction analysis under the same conditions as described above. In addition, a laser diffraction particle size distribution analyzer [“SALD1100”
(Manufactured by Shimadzu Corporation)], and analyzed by a differential thermal analyzer [“TAS-200” (manufactured by Rigaku Corporation)] for a 600-800 ° C. weight loss.
The remaining amount of calcium carbonate was measured. These X-ray diffraction analyses,
The average particle size and the residual amount of calcium carbonate are shown in Table 1 below together with the yield.

[0027]

[Table 1]

The particle size distribution of the raw material powder and the product powder was measured by the above laser diffraction type particle size distribution measuring apparatus. The results are shown in FIGS. That is, FIG. 3 shows the particle size distribution of the raw material powder (containing calcium carbonate) in Example 2, FIG. 4 shows the particle size distribution of the product powder (carbonic apatite) in Example 2, and FIG. 6 shows the particle size distribution of the product powder in Example 3, FIG. 7 shows the particle size distribution of the raw material powder in Example 4, and FIG. 8 shows the particle size distribution of the product powder in Example 4. It is a thing. 3 to 8, Q (%) indicates an integral value, and q (%) indicates a differential value.

From the average particle diameter shown in Table 1 and the results shown in FIGS. 3 to 8, it can be seen that the average particle diameter of the massive carbonate apatite can be controlled by controlling the average particle diameter of the calcium carbonate-containing substance. I understand.

As described above, carbonate apatite has a hydroxyl group (O) of the chemical formula Ca ₁₀ (PO ₄ ) ₆ (OH) _2.
There are A type in which a part of H ⁻ ) is substituted with a carbonic acid group (CO ₃ ^2- ) and B type in which a part of a phosphoric acid group (PO ₄ ^3- ) is substituted with a carbonic acid group. The B-type carbonate apatite can be identified by the general formula Ca _10-x (P
O ₄ ) _6-x (CO ₃ ) _x (OH) _2-x

The present inventors have identified carbonate apatite and calcium carbonate using an infrared absorption spectrum apparatus [“FT-IR”] (manufactured by Shimadzu Corporation). At this time, the following frequencies were used for identification. (A) B-type carbonate apatite: 1465, 1
412 (cm ^-1 ) (b) Calcium carbonate (calcite): 712 cm ^-1 (c) Calcium carbonate (aragolite): 855 cm ^-1

On the other hand, the total amount of (CO ₃ ^2- ) was measured with a CHN meter [“MT-3” (manufactured by Yanagimoto Seisakusho)], and the remaining calcium carbonate amount shown in Table 1 was determined from the measured value. the reduced values were substituted into ^{_{(PO 4 3-) (CO 3}} 2-)
It was determined as an amount. These results are shown in Table 2 below together with the molecular formula of the obtained B-type carbonate apatite.

[0033]

[Table 2]

[0034] From these results, by controlling the reaction rate, Formula _{Ca 10 (PO 4) 6 (} OH) in the apatite represented by ₂ (PO ₄ ^3-) 0.01~1mo
It can be seen that (CO ₃ ^2- ) can be substituted in the range of l.

[0035]

As described above, according to the present invention, the following effects can be obtained. (1) As carbonic apatite, the particle size and carbonic acid content can be controlled within a certain range. (2) When using shells as a raw material for calcium carbonate,
In addition to the passive reason of using waste, the pharmacological effect of the shell can be expected by reacting in the neutral region and adjusting the amount of reaction to leave unreacted substances. (3) Since the method of the present invention does not use various buffers and does not generate by-products and is a simple production process, mass production is possible. (4) The carbonate apatite according to the present invention is a porous body having a large specific surface area, and can provide carbonate apatite fine particles having excellent adsorption characteristics.

[Brief description of the drawings]

FIG. 1 is a graph showing an X-ray diffraction result of carbonate apatite obtained in Example 1.

FIG. 2 is a drawing-substituting micrograph showing the crystal structure of carbonate apatite obtained in Example 1.

FIG. 3 is a graph showing a particle size distribution of a raw material powder in Example 2.

FIG. 4 is a graph showing a particle size distribution of a product powder in Example 2.

FIG. 5 is a graph showing a particle size distribution of a raw material powder in Example 3.

FIG. 6 is a graph showing the particle size distribution of a product powder in Example 3.

FIG. 7 is a graph showing a particle size distribution of a raw material powder in Example 4.

FIG. 8 is a graph showing a particle size distribution of a product powder in Example 4.

Claims (6)

[Claims] 1. A porous massive carbonate apatite comprising at least 0.5% by weight of calcium carbonate and having a BET specific surface area of at least 10 m ² / g. 2. The method for producing a massive lump carbonate apatite according to claim 1, wherein the lactate containing calcium carbonate is reacted with phosphoric acid in a neutral region to produce the lump apatite according to claim 1. 3. The production method according to claim 2, wherein the calcium carbonate-containing substance is a natural product. 4. The method according to claim 3, wherein the calcium carbonate-containing substance is a shell. 5. The method according to claim 2, wherein the average particle diameter of the bulk carbonate apatite is controlled within a range of 1 to 50 μm by controlling the average particle diameter of the calcium carbonate-containing material to 0.5 to 20 μm. The production method described in Crab. 6. The chemical reaction by controlling the reaction rate.
Formula Ca_Ten(PO_Four ) ₆ (OH)_Two Apatite represented by
Inside (PO_Four ^3-) In the range of 0.01 to 1 mol (CO
_Three ^2- The method according to any one of claims 2 to 5, wherein
The manufacturing method as described.