JPS61151009A - Production of hydroxy apatite - Google Patents

Abstract

PURPOSE:To obtain the titled compound having a desired Ca/P ratio in a short time in good reproducibility, by adding CaO and/or Ca(OH)2 to slurry of CaHPO4.2H2O and water to give a solid reaction product, and heating it. CONSTITUTION:CaO And/or Ca(OH)2 is gradually added to and reacted with slurry of CaHPO4.2H2O and water while keeping pH<=10, temperature at 5-70 deg.C optionally in an inert gas atmosphere such as N2, etc. until it reaches 80wt% theoretical amount added, and the rest of CaO and/or Ca(OH)2 is added to the reaction mixture, a solid reaction product is filtered and separated. The separated solid product is heated at >=100 deg.C until water content becomes <=5wt%, to give easily high-purity hydroxy apatite having 1.48-1.67 Ca/P ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing hydroxyapatite (HAp).

In recent years, phosphoric acid compounds, especially HAp, have attracted attention as biomaterials and are used in artificial bones, artificial teeth, and the like. This is HA
This is because when p is implanted in a living body, it is safe and chemically stable, and it also easily fuses with natural bone and heals without causing a rejection reaction in the living body.

Other uses of HAp include as a raw material for bone china, a type of high-grade porcelain, and as a filler for chromatography.

[Prior art]

In general, two methods are known for producing HAp: a dry method using a solid phase reaction under high temperature, and a wet method using a water bath liquid reaction or hydrothermal reaction under atmospheric pressure.
．． It is difficult to call this an industrial method because it requires long-time firing at a high temperature of 000° C. or higher (1), and the equipment is expensive.

In addition, among the wet methods, as a method using hydrothermal reaction, Ca
HPO4・2H2O (or Ca1l)04) and Ca
A method based on the reaction of (OH)1 is known (JP-A-5
3-111000). In this method, each raw material is mixed in solid form, and this mixture is placed in an autoclave for 10 minutes.
This is a method for producing crystalline HAp by carrying out a hydrothermal reaction under hot water at 0 to 500°C and 1 to 500 atm.

However, this method has the drawback that the reaction equipment is expensive due to the severe reaction sweat, and the energy cost is also high.

On the other hand, as a method for producing HAp using an aqueous solution method, a method using neutralization of phosphoric acid is known, but the reaction rate is high and the resulting precipitate is colloidal, which is inconvenient in terms of handling and operation. . In addition, when using HAp as a biological material, which is the main use of HAp, if it contains more than a certain amount of iron, zinc, lead, etc., these ions may be eluted in the living body, so HAp must be made with very few impurities. is required, so when using phosphoric acid as a raw material,
Removal of impurities becomes extremely troublesome.

As an extremely industrial method that is completely different from the above methods,
The Ministry of the Invention and others have already proposed an aqueous solution method in which Ca(OH) is added to a slurry of CaHPO4.2H20 and water and the reaction is carried out under atmospheric pressure (Japanese Patent Application No. 1-110947
issue). This method is Oa (OH)! By constantly adding 11111Jj to keep the pH below 10 until the molar ratio is 1.6, high
HAp can be left behind.

[Problems with conventional technology]

Among the methods for producing Hkp proposed in the past, both the dry method and the hydrothermal reaction method required expensive equipment and were disadvantageous in terms of energy, and were unsuccessful. Furthermore, among the aqueous solution methods, the method using phosphoric acid neutralization has problems in handling the product and is not suitable for producing high-purity HAp.

On the other hand, in the method already proposed by the Ministry of the Invention and others, the Ca/p molar ratio of HAp once generated may vary during the filtration and washing operation, and the reproducibility
/p molar ratio of HAp f is not necessarily satisfied.
It wasn't something.

[Problem that the invention seeks to solve]

The present invention is intended to solve the above-mentioned problems of the prior art.In particular, the method of Japanese Patent Application No. 110947/1983 is used to obtain HAp f with a desired CI3//p molar ratio with good reproducibility.
The purpose is to obtain.

[Means for solving problems]

That is, the present invention is a slurry solution of CaHPO4.2H10 and water at a temperature of 115 to 70°C (up to 80% of the theoretical addition amount of ao and/or Ca(OH)1).
This is a method for producing HAp, which is characterized by adding the mixture at a constant temperature so as to keep the amount below, then adding the remaining amount, separating the generated solid content by filtration, and heating the separated product to 100°C or higher.

To explain the present invention in more detail, CaHPO<・2H
! The basic reaction formula using Ca(OH)2 as the Ca source and Ca(OH)2 is shown below.

6C! aHPO4-2H2O+ 4Ca(OH),
-Ca1゜(FO4)s (OH)x↓+18H,0 In this case, even if an equivalent amount of Ca(OH)1 is added all at once to a slurry solution of Ca)IPO4.2H20 and water at a reaction temperature of 100℃ or less, the reaction will not occur. is extremely slow (HAp is difficult to generate).

However, when Ca(OH)*t is continuously or intermittently supplied to the CaHPO4/2H20 slurry within a range that does not exceed each reaction rate, the pH value of the reaction solution must be adjusted so as not to exceed a specific value. Shinaka Ca(O)
i) If the z solution is supplied, the reaction will easily proceed and be completed. Control of pH is a major factor in this reaction; for example, at a reaction temperature of 50° C., up to 87% of the theoretical addition amount of Ca(OH) is reacted at a pH of 10 or lower, preferably 9.0 or lower. Thereafter, the reaction is carried out at a pH of 9 or higher to give a theoretical Oa/p ratio of 67 HApt-sweet acid.

Also, the preparation Cψ ratio is slightly lower! , 67, it is possible to remove j)Ca(OH)zk by subsequent washing, so that HAp with an Oa/p ratio of 1.67 can be easily obtained.

In this reaction, the pH at the time of the reaction is an extremely important factor, and in order to complete the reaction, it is necessary to pay sufficient attention to pH1tilJ@l.In particular, the amount of Ca(OH)1 added is less than the theoretical amount If the pH is not kept below 80%, unreacted CaHPO4.2H20 remains and HAp cannot be obtained.

The reaction temperature is usually 5 to 70°C, preferably 30 to 70°C in order to speed up the reaction. At temperatures below 5°C, the reaction progresses slowly, which is undesirable. At temperatures above 70°C, CaHPO4-2H10 becomes CaJ(P0
It should be avoided as it metastasizes to stage 4.

In addition, by changing the supply amount (preparation Oa/p ratio) of the Oa/p ratio rt Ca(OH) of the product HAp, the Ca(OH)
HAp with a /p ratio of 1.48 to 1.67 can be easily obtained.

After the HAp thus produced is separated by filtration by a conventional means, the separated product is heated to 100°C or higher, preferably 13°C.
Heat to above 0°C. The heating time may be selected depending on the heating temperature and the water content of the separated material so that the water content at the end of heating is 5 cm or less.

This treatment can prevent the CIVp molar ratio from changing due to washing in the next step.

Furthermore, in the present invention, the ca(on) used does not matter whether it is supplied as a powder or a slurry.

Of course, CaO may also be used as a substitute for aa(o$t).Also, in order to suppress the mixing of aOS ions into the product HAp as low as possible, an inert gas (for example, N!
etc.) It is desirable to conduct the reaction in an atmosphere.

The HAp obtained in the present invention is a fine particle plate-like powder, and can be used as a biomaterial as it is or by molding or sintering with other organic materials such as cellulose or collagen, or as a composite with other organic or inorganic matrices. It can also be used satisfactorily as a chromatography filler.

The present invention will be explained in detail below with reference to Examples.

Examples 1 to 7, Comparative Example 1. 2 60β with lid of SU3304g with hot water jacket
A stirrer, pH correction, thermometer, and reflux condenser were set in the reactor, and the internal K CaHPO4. 10% lime milk preheated by a hot water jacket was supplied from the milk tank to the reactor using a bonder, and a reaction was carried out.

After the reaction was completed, the product was filtered off, and after heating, excess Ca (
OH) was washed off and dried.

The reaction conditions and results are shown in Table 5g1. In addition, the relationship between the addition rate of pH and ca (oH) at each reaction time in Example 1 is shown in Figure 1, and the x-ray diffraction pattern of the obtained product is shown in Figure 1.
Shown in Figure 2.

Comparative example 3 CaHr04-2H202,0A1iI, H2O30
Charge 2OQ into the reactor and at a temperature of 50℃, ca(OH)
, 6.09 # of 10% slurry was fed all at once, and the charged Ca/p ratio was set to 1.69.

The pH of the reaction solution was 11.3, and after a reaction time of 30 hours, 9 products were taken out, filtered, and dried. As a result of analyzing this with an X-ray diffraction device, only a very small amount of HAp was observed. This X++f1 diffraction pattern is shown in FIG.

〔Effect of the invention〕

According to the present invention, it is possible to easily obtain hydroxyapatite useful as a biomaterial, etc., and to obtain a desired Oa/p ratio with good reproducibility.

[Brief explanation of drawings]

Figure 5 shows pH and C at each reaction time in Example 1.
a (OHh) is a graph showing the foil weighting coefficient. Figures 2 and 3 are for Example 1 and Comparison, respectively.
This is the X-ray diffraction pattern of No. 5.

Claims (1)

[Claims] CaO in the slurry of CaHPO_4・2H_2O and water
In a method for producing hydroxyapatite by adding and/or Ca(OH)_2, C at a temperature of 5 to 70°C.
80 of the theoretical addition amount of aO and/or Ca(OH)_2
Add CaO and/or Ca(OH)_2 gradually while keeping the pH below 10 until the addition of %, then add the remaining amount, separate the resulting solid, and heat the separated solid at 100°C.
A method for producing hydroxyapatite, which comprises heating to a temperature higher than 100%.