JPH05329B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing hydroxyapatite, which is attracting attention for its use as a raw material for an adsorbent substitute for biological hard tissues. [Prior art and its problems] The crystal of hydroxyapatite [Ca ₁₀ (OH) ₂ (PO ₄ ) ₆ has a crystal face with a positively charged Ca group (Ca site) and a negative charged PO ₄ group. Since it has a crystal plane with (P site), COOH group and
It has the ability to adsorb biopolymers (proteins) containing NH ₂ groups, and its use as a separation adsorbent is attracting attention. Furthermore, hydroxyapatite is originally considered to be a major component of bones and teeth, and the use of artificially produced apatite as a prosthesis for bone and tooth defects is becoming more concrete. The artificial manufacturing method of this apatite is as follows.
phosphates, calcium salts and/or apatite precursors [CaHPO ₄ , Ca ₃ (PO ₄ ) ₂ , Ca ₄ H
(PO ₄ ) ₃ ), a dry method in which a solid phase reaction is carried out at high temperature conditions, a wet method in which a liquid phase reaction is carried out in the atmosphere, and a hydrothermal method in which a reaction is carried out under hydrothermal conditions at high temperature and high pressure. The reaction is known. The dry method involves solid phase reaction of calcium salt and phosphate at high temperature in the presence of an apatite precursor.
This is a method for producing apatite, but if the particle size or mixing state of the powder to be reacted is not uniform, a distribution may occur in the solid phase reaction, and apatite may not be completely formed, such as containing amorphous apatite. In addition, in hydrothermal reactions, 100~
Phosphates and calcium salts are reacted under hydrothermal conditions of 500°C and 200 to 500 atm, but the reaction conditions are harsh and the reaction equipment and manufacturing costs are expensive. The wet method is a method of producing apatite by ripening the apatite precursor obtained through the process of neutralizing phosphate with an alkali at high temperatures, but it takes a very long time to ripen it into apatite. . On the other hand, as a method for producing apatite, a method using apatite contained in natural products is also known. For example, animal bones can be directly used as a prosthesis for human bone defects, or animal bones can be burned and then crushed to be used as a raw material for artificial bones. However, the composition of animal bones varies depending on the species, site, age, etc., and there is a particular distribution in the content of carbonate apatite. When raw materials with a high carbonate apatite content are fired, CO ₂ is emitted during the firing process.
is removed, resulting in apatite with some remaining CaO. When these are used as raw materials for adsorbent artificial bone, they come into contact with liquid and elute alkali, so
There were concerns that the adsorption power would decrease and that it would have an adverse effect on living organisms. [Object of the Invention] The object of the present invention is to solve the problems in the prior art described above and to produce stable and highly pure apatite at a low cost. [Structure of the Invention] The present invention involves firing animal bones in an oxidizing atmosphere at a temperature within the range of 600 to 1200°C, and then finely pulverizing the bones.
This method of producing hydroxyapatite is characterized by immersing it in a phosphate ion-containing solution and then washing it with water. As a result of intensive research into the production method of apatite, the inventors discovered that they can produce apatite using animal bones (livestock bones, fish bones) as raw materials, which have not always been effectively used in the past.
We have invented a method for producing stable and pure apatite. Bone is composed of approximately 65% inorganic material and 35% organic material, and the composition of inorganic material varies depending on the type of animal, location, and
Although it varies somewhat depending on age, etc., Table 1 shows a representative sample of dried human bone.

[Table] The main inorganic salts (called bone minerals) that make up bones are:
[Ca ₁₀ (OH) ₂ (PO ₄ ) ₆ [Ca (OH) ₂・3Ca ₃ (PO ₄ ) ₂ ]
In addition, carbonate apatite [CaCO ₃・3Ca ₃
(PO ₄ ) ₂ ]. In the present invention, stable and highly pure apatite is obtained by calcining the animal bone under predetermined temperature conditions in an oxidizing atmosphere and then subjecting it to physicochemical treatment. Embodiments of the invention are as follows. Beef bones that have been cleaned and degreased in advance are fired in the air at approximately 1000℃. By baking beef bones, fibrous proteins, collagen, sugars, etc. are removed, and at the same time, they are sterilized. Firing improves the crystallinity of apatite (the peak of X-ray diffraction becomes sharp) and facilitates the material to be easily crushed. However, during the firing process, each component in bone mineral is
CO ₂ and H ₂ O are released, and partially [CaO・3Ca ₃
(PO ₄ ) ₂ ]. Therefore, after the calcined beef bones are crushed in a crusher, they are sieved and classified as necessary, and then immersed in a solution containing phosphate ions, and through this immersion treatment, they are gradually dissolved in the liquid.
Fix and stabilize CaO with phosphate ions. Excess phosphoric acid is removed by washing with water. In order to further promote the fixation of CaO content and apatite formation, it is necessary to use high temperature and Ca(OH) ₂ , KH ₂
It is best to immerse it in a solution containing PO ₄ . This immersion brings the crystal structure closer to pure apatite. in the soaking liquid to increase the maturation rate of apatite.
For example, Ca(OH) ₂ or NaOH is added to a concentration that maintains the pH between 7 and 9, and the amount of phosphate ions is lower than the amount that can react with the CaO content in the calcined bone mineral. It is also preferable to set it to an excessive value. After the immersion treatment, it is separated from the immersion liquid and washed with water to wash out impurities such as excess salts and heavy metals. The phosphoric acid-containing solution to be immersed in is 0.01 to 5%.
It is preferable to use a solution of about Phosphoric acid sources include H ₃ PO ₄ , KH ₂ PO ₄ , K ₂ HPO ₄ , Na ₃
PO ₄ , (NH ₄ ) ₃ PO ₄ etc. can be used. Note that the firing temperature is preferably 600 to 1200°C. With this method, stable and highly pure apatite can be produced by using bone mineral in animal bones and performing chemical and physical treatments after firing.Furthermore, the structure of this apatite is originally Since it uses something that already existed, it provides a material that is also preferable as a raw material for artificial bones and artificial tooth roots. Example 1 After baking 100g of washed beef bones in air at 500℃, 600℃, 1200℃, and 1300℃,
The particles were ground with a grinder to adjust the particle size to 50 to 100 μm, and immersed in a 3% KH ₂ PO ₄ solution at room temperature for about 30 minutes. Thereafter, each bone was washed with 10 times the amount of water as the beef bone. X-ray diffraction pattern and Ca/P of each sample
The ratio was measured. The results are shown in Figure 1. At 500℃,
Although the peak of apatite is unclear, when fired at 600°C or higher, the peak of apatite becomes sharp (good crystallinity). That is, the crystallinity was improved. Moreover, the Ca/P ratio of pure apatite is 2.15, but the Ca/P ratio becomes almost constant at temperatures above 600°C. Note that when fired at 1300°C, some melting occurred, making it difficult to recover the material. Samples fired at 600 and 1000°C did not elute alkali even when immersed in fresh water. Example 2 100g of beef bone was calcined in the air at 600°C, then crushed in a crusher, and the particle size was adjusted to 10 to 20μm.
This is Ca(OH) ₂ 1% at 10℃, 20℃, 60℃, 80℃,
It was immersed in a 2.5% KH ₂ PO ₄ solution for 2 hours, and then washed with water. A sample was also obtained which was immersed in a solution containing 2.5% KH ₂ PO ₄ at 80° C. for 2 hours and then washed with water. The X-ray diffraction pattern of each sample is shown in FIG. As a result, the crystallinity of apatite was good when it was immersed in a solution containing slaked lime and phosphate ions at 600°C or higher. On the other hand, in the case of no immersion, the apatite had poor crystallinity, and when immersed in fresh water, alkali was eluted.

[Brief explanation of the drawing]

Figure 1 shows the calcining temperature of beef bones, the X-ray diffraction pattern of the product, and the Ca/P ratio, and Figure 2 shows the calcining temperature of beef bones.
FIG. 2 is a diagram showing the immersion temperature in a KH ₂ PO ₄ solution, the X-ray diffraction pattern of the product, and the Ca/P ratio.

[Claims]

1 The following general formula Na _a Al _b H _c (PO ₄ ) _d・nH ₂ O (where a, b, c, d and n are a+3b
+c=3d is also 0.6 to 3.3, respectively, while maintaining the relationship.
1.8 to 3.3, 12 to 16, 7 to 9, and 0 to 5), the precursor solution of the acid phosphate is converted into a solid. A method for producing crystallized sodium acid aluminum phosphate, characterized in that it is sprayed onto a stirred bed of particles. 2. Process according to claim 1, characterized in that the solid particles have the same composition as the acid phosphate to be produced. 3. Claim 1 characterized in that the stoichiometric proportion of the precursor solution is such that it corresponds to obtaining acid sodium aluminum phosphate of the formula NaAl ₃ H ₁₄ (PO ₄ ) _{8.4H 2} O. or the method described in any of 2.