JPS6246908A - Production of hydroxyapatite - Google Patents

Abstract

PURPOSE:To easily produce hydroxyapatite having a desired molar ratio of Ca/P in a short time by hydrolyzing slightly water-soluble calcium phosphate and adding Ca<2+> to the hydrolyzates so as to increase the molar ratio of Ca/P. CONSTITUTION:An adequate amount of water is added to slightly water-soluble calcium phosphate such as CaHPO4, CaHPO4.2H2O or Ca3(PO4)2, and the resulting slurry is made alkaline with an aqueous NH4OH soln. and refluxed under heating to convert the calcium phosphate into nonstoichiometric hydroxyapatite having <1.67 molar ratio of Ca/P. A Ca<2+> ion source such as CaCl2.2H2O is then added, the alkali is further added and reflux under heating is continued. At this time, the molar ratio of Ca/P is increased to an arbitrary value of <=1.67 by controlling the amount of Ca<2+> added and the reaction time. Hydroxyapatite having 1.67 molar ratio of Ca/P is separated by filtration and washed to obtain high purity hydroxyapatite.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for producing hydroxyapatite.

Hydroxyapatite has the general formula % (where n represents O~2.5 + Z represents 0~l)
It has a chemical composition similar to the main component of in-vivo dental bone, and is useful as an artificial tooth root, an artificial bone, or a filling material therefor. It also acts as an adsorbent for biopolymers, biohazardous organic substances, or inorganic ions.

Conventional technology: As a conventional method for producing hydroxyapatite, (1)
Solid phase reaction method (2), hydrothermal reaction method (3) precipitation reaction method (4) and hydrolysis method are known.

The solid phase reaction method (1) is a method of firing in the coexistence of water vapor at a high temperature of 1000°C or higher, and the water reaction method (2) is also carried out in a sealed pressure-resistant container and under high pressure, so in both cases the reaction equipment is It is expensive, and the obtained hydroxyl avatarite powder has disadvantages that make it unsuitable for the above-mentioned uses.

In the precipitation reaction method (3), the obtained hydroxyapatite powder is highly active and easily sintered, but since the precipitate is colloidal, it is inconvenient to handle and it is difficult to wash and remove impurity ions. However, it also has the disadvantage of poor reproducibility of chemical composition.

The hydrolysis method (4) is a method that improves the method (3) above, and includes, for example, CaHPO41 or CaHPO,
A method is known in which a slurry solution of -2H2O and water is maintained at a basic pH of 10 or less and Ca(OH)2 is supplied continuously or intermittently. However, this method has the disadvantage that it requires a long reaction time of 40 hours or more at a reaction temperature of 50 DEG C. (Japanese Unexamined Patent Publication No. 60-5009).

In this case, Ca(OH) in the coexistence of an organic solvent such as n-pentane or tert-butanol.

However, it can be obtained by shortening the addition of f'JIK by 2 hours (Japanese Patent Application Laid-Open No. 58-190807, JP-A No. 59-217610)
However, it has the disadvantage that it requires an organic solvent and the subsequent treatment is troublesome.

Purpose of the Invention The present invention was made in order to eliminate the drawbacks of the hydrolysis method described in (4) above. The present invention provides a method for manufacturing apatite.

Structure of the Invention In order to achieve the above object, the present inventors investigated the reaction mechanism for producing hydroxyapatite by hydrolysis of poorly water-soluble calcium phosphate. We found that apatite absorbs Ca and the Ca/P molar ratio changes to 1.67.
It was found that hydroxyapatite can be easily produced in a short time by first hydrolyzing poorly water-soluble calcium/umium phosphate and then adding Ca to it and increasing the Ca/P molar ratio. . The present invention was completed based on this knowledge.

The gist of the present invention is to hydrolyze poorly water-soluble calcium phosphate in a basic aqueous solution to produce non-chemically short-tubular hydroxyapatite with a Ca/P molar ratio of less than 1.67, and to this, a basic aqueous solution Ca by adding carunium ions under
The method for producing hydroxyapatite is characterized by increasing the /P molar ratio to an arbitrary ratio up to 1°67.

Examples of poorly water-soluble calcium phosphate include campo
Examples include 4.2H201CaHPO,, Ca3(PO,)2. However, it is not limited to this.

The basic reaction formula for the hydrolysis of poorly water-soluble calcium phosphate in the first step of the production method of the present invention is as follows.

(1O-Z)CaHPO,-2H20+ ((2-Z)
+n) H20→G a, o-7, (HPO,)z
(PO,) 6-z(OH)2-z HnH2O+ (
a-z) H3PO4+2(+oz)H,,0(10-
Z) CaHPO41(2-Z)+n) H20→Ca
+ O-z (HP 04) Z (POa)
b -z (OH) 2-z-n H20+ (4-
z) H, PO.

(10-z) ca, (po,) 2 + (3(2-
z) +3n,) H20→3Ca,,2(HPO
,)z(F04)6-2(OH)2-z-nl(20”
2 (+ −z)H, PO.

In this case, the production of hydroxyapatite is unlikely to occur even if Ca2+ coexists or the pH is too high or too low. Therefore, Ca
is not added, and the pH is maintained within the range shown in FIGS. 1 and 2 for hydrolysis.

In the second step, Ca is added to cause an absorption reaction. The reaction formula is as follows.

Ca, oz(HPO4)7J(PO4)6-z(OH
)2-z-nH20+ZCa2″'=+zOH--+
Ca. (PO4)6(OH2)+zH"+n
H,,L) In this case, Ga2+, which increases the pH, is well absorbed (see Figure 3), so it is better to have a pH of 9 or higher.
I KOHI Ca(OH)21 NH,l NH,0
HINH2CCCH,,G).

(C)15)4NOH etc. are mentioned.

In addition, as a Ca source, for example, CaCl2-2H
2CLcao l CaF2T CaCO3, (CH,
C00)2Ca and the like.

In the hydrolysis reaction, an appropriate amount of water is added to the raw material, poorly water-soluble calcium phosphate, to make the pH alkaline, and then heated and refluxed. After several hours of heating and refluxing, non-chemical hydroxyapatite with Ca/'P = about 1.50 (as shown in the table).

Thereafter, Ca is added, and then an alkali is added, and heating and refluxing is continued. At this time, by controlling the amount of Ca added and the reaction time, hydroxyapatite with a Ca/P of 1.50 to 1.671 can be obtained. At this time, the reaction time is faster if the pH is as low as possible, so it is usually pH 9 or higher (the third
(see figure). Oa/P=1 by heating reflux
．． The hydroxyapatite converted to 67 is separated. For example r
Highly purified hydroxyapatite can be obtained by filtering and washing.

Example 1 202 tons of CaHPO44H and 200 ml of water were placed in a beaker, heated with stirring to raise the temperature to 40°C, and
The pH was maintained at 8 with u40f (and the reaction was allowed to take place for about 3 hours. At this time, the powder in the beaker had been converted to hydroxyapatite with Ca/P = 1.50.
02F was added, the pH was adjusted to 1O with NH40H, and the reaction was further advanced.

After 3 hours, the liquid in the beaker was separated and dried. What was obtained was white hydroxyapatite powder with Oa/P=1.67.

Example 2 CaHPO,sy and 1,501 liters of water were added to a heater and heated while stirring to raise the temperature to 80°C. N for this
The pH was adjusted to 9 by adding H and OH, and the reaction was allowed to proceed for about 1 hour. Add 57 u, cact2・2H20, 1.
Of-! The pH was adjusted to 9 and the reaction proceeded. After 2 hours, it was dried and a white powder was obtained. This powder is CaHPO4,6
2: It was hydroxyapatite.

Example 3 α-TcP(C!a, (PO,)2) 5 Y, water 1
Pour 50 m in a beaker and heat while stirring to 80 m
The temperature was raised to ℃.

NH,0)1 was added to this to maintain the pH at 10 and the reaction was allowed to proceed for about 2 hours. After that, add 1.5% CaCl2・2H20
2 was added, the pH was adjusted to 9 with NH40), and the reaction proceeded. The mixture was reacted for about 2 hours and dried to obtain a white powder. This powder was hydroxyapatite with Oa/P = 1 and 67.

Effect of the invention The present invention has the following excellent effects.

(1) Compared to the conventional precipitation method using a non-organic solvent system, the production time is about -1, and hydroxyapatite of 1O 2 CaHPO 4,67 can be easily and stably produced.

(2) Hydroxyapatite can be produced in a short time at a low temperature of 100° C. or lower, without requiring a high-temperature and pressure-resistant container as in conventional solid-phase reaction methods or hydrothermal reactions.

(3) By controlling the supply amount of Ca2+ ions and the reaction time, the Ca/P molar ratio can be adjusted from 1.50 to 1.
．． 67 can be made into hydroxyapatite of any composition.

(4) Since it easily becomes hydroxyapatite that inherits the powder shape of the starting material, it can be easily filtered and washed, and it can be made with high purity.

[Brief explanation of drawings]

Figure 1 shows p in the hydrolysis of CaHPO4.2H20.
Figure 2 shows the relationship between H and the production rate of hydroxyapatite.
FIG. 3 shows the X-ray diffraction diagram of the hydrolyzed product of HPO4.2H20, and the relationship diagram between the pH in the Call collection reaction and the Ca/P molar ratio of the produced hydroxyapatite. Patent applicant Goto, director of the Institute for Inorganic Materials, Science and Technology Agency
Excellent Figure 1 H Figure 2 Ward 3 H

Claims (1)

[Scope of Claims] 1) Hydrolyzing poorly water-soluble calcium phosphate in a basic aqueous solution to form non-stoichiometric hydroxyapatite with a Ca/P molar ratio of less than 1.67; A method for producing hydroxyapatite, characterized in that calcium ions are added in a basic aqueous solution to increase the Ca/P molar ratio to any ratio up to 1.67. 2) Poorly water-soluble calcium phosphate is CaHPO_4, C
aHPO_4・2H_2O, Ca_3(PO_4)_2
A method for producing hydroxyapatite according to claim 1.