JPH03290351A - Production of high-density apatite ceramics - Google Patents

Abstract

PURPOSE:To obtain apatite ceramics having high density and improved light transmission properties by impregnating apatite powder with an aqueous solution of water-soluble Ca salt of an organic acid, drying, molding and burning. CONSTITUTION:Apatite powder is impregnated with <=0.5wt.% calculated as CaO of an aqueous solution of water-soluble Ca salt (e.g. calcium acetate) of an organic acid, dried, molded by a conventional procedure and burnt.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a method for manufacturing high-density apatite ceramics.

"Prior art and its problems" Since apatite ceramics have excellent biocompatibility, their applications as various biomaterials are being considered.

To achieve high strength suitable for use as a biomaterial, apatite ceramics must be densified, but if the Ca/P ratio is less than the stoichiometric ratio (lack of calcium), the densification is insufficient. It is known that there is no densification. In addition, even if the raw material powder is determined to be pure hydroxyapatite by X-ray diffraction, the density may not be improved by normal sintering (even if the sintering temperature is increased or the holding time is extended), the density may not be improved. many.

In Japanese Patent Application Laid-open No. 53-81499, Ca/P=1
．． A method has been proposed in which crystalline apatite is produced by producing apatite with a particle size of 67 or less, mixing the insufficient amount of Ca with an inorganic calcium compound, and reacting the mixture with a hydrothermal reaction or a solid phase reaction. However, with this method, the insufficient C
Since a is mixed with powder of an inorganic calcium compound, it is difficult to uniformly add insufficient Ca. In addition, agglomeration of particles occurs in the process of mixing powders, resulting in coarse particles, making it impossible to obtain high-density ceramics.

Furthermore, there is no known method for adjusting the Ca/P ratio of apatite ceramics in the form of a molded body.

"Objective of the Invention" An object of the present invention is to provide a method for manufacturing high-density ceramics by adjusting the Ca/P ratio of apatite ceramics in the state of powder or compact.

"Structure of the Invention" The method for producing high-density apatite ceramics according to the present invention includes impregnating apatite powder with an aqueous solution of a water-soluble calcium salt of an organic acid, drying, shaping, and firing, or dry-molded apatite, It is characterized by impregnating a dry molded product or a calcined molded product with an aqueous solution of a water-soluble calcium salt of an organic acid, drying it, and then firing it.

The method of the present invention can be applied to apatite powder or compacts. The molded body may be a compacted powder body formed by dry molding, a dry molded body that is dried after wet molding, or a calcined molded body that is further calcined.

In addition, in the apatite powder or molded body used in the present invention, the apatite is pure apatite according to X-ray diffraction, or has a composition lacking Ca, but various types such as hydroxyapatite, fluoroapatite, chlorapatite, etc. may be apatite.

In the present invention, calcium acetate, calcium oxalate, calcium lactate, calcium tartrate, calcium citrate, and the like can be used as water-soluble calcium salts of organic acids. The amount of such a water-soluble calcium salt of an organic acid added depends on the amount of calcium deficiency in the apatite used, but the amount of impregnation of the calcium salt is 0.5% in terms of CaO.
It is preferable that the amount is 5% by weight or less. When this amount exceeds 0.5% by weight, the CaO phase in the apatite phase becomes excessive, and many cracks occur in the sintered body due to the difference in coefficient of thermal expansion during sintering.

When impregnating with an aqueous solution of a calcium salt of an organic acid, it is preferable to use a solution as highly concentrated as possible, such as a saturated solution, taking into account the subsequent drying energy. Further, impregnation can be performed by dropping, spraying, etc.

When impregnating powder, it is dried in a conventional manner, then shaped and fired in a conventional manner. Moreover, when impregnating a molded body, the molded body may be baked in a conventional manner after drying.

"Examples of the Invention" Next, the present invention will be described in more detail based on Examples, but the present invention is not limited thereto.

Example I According to X-ray diffraction, a cylindrical green compact (weight 5.0 g) with a diameter of 25 mm and a height of 6.3 mm made of pure hydroxyapatite was prepared, and 2.76% by weight was added to the green compact. It was impregnated with 2.1 yd of calcium acetate aqueous solution (an amount such that the amount of calcium salt impregnated is 0.5% by weight in terms of CaO) by absorbing it drop by drop. After being left to dry naturally for about one day, it was sintered at 1050° C. for 4 hours. The X-ray diffraction pattern of the obtained sintered body is shown in FIG. Figure 1 shows some C
An a○ peak (indicated by a in the figure) is seen, which indicates that the sintered body has an abatite structure. Furthermore, the density of the obtained sintered body was measured, and the translucency was measured using an optical microscope. The results are shown in Table 1.

Note that the evaluation of the light transmittance was performed based on the light transmittance of the sintered body of the following comparative example.

Example 2 A sintered body was produced in the same manner as in Example 1, except that 2.41 nl of a 4% by weight calcium lactate aqueous solution was impregnated instead of the 2.76% by weight aqueous calcium acetate solution, and the obtained sintered body Body density and translucency are shown in Table 1.

Example 3 The green compact produced in Example 1 was calcined for 4 hours in an electric furnace set at 900°C. The obtained calcined body (weight 5.0 g) was impregnated with 2.1 ml of a 2.76 wt% calcium acetate aqueous solution (an amount that makes the amount of calcium salt impregnated 0.5 wt% in terms of CaO), and then It was sintered at ℃ for 4 hours and the density was measured. The results of measuring the relative density of the sample at each time point are shown below.

Green compact 5”18% Calcined compact 7Z4% Sintered compact 98.3% Untreated sintered compact 95.4% Comparative Example 1 Same compact as Example 1 except that no impregnation was performed.
The X-ray diffraction pattern of the obtained sintered body is shown in FIG. 2, and the measurement results of density and translucency are shown in Table 1.

Table 1 As is clear from these results, according to the method of the present invention, a high-density, translucent apatite sintered body was obtained.

"Effects of the Invention" According to the method of the present invention, high density can be achieved with simple operations, and apatite ceramics with high density and translucency can be obtained. Further, according to the method of the present invention, a high-density ceramic molded body can be manufactured by adjusting the Ca/P ratio of the apatite ceramic even in the state of the molded body.

[Brief explanation of the drawing]

Figure 1 is an X-ray diffraction diagram of the surface of the sintered body produced in Example 1,
FIG. 2 is an X-ray diffraction diagram of the surface of the sintered body produced in Comparative Example 1. Explanation of symbols a...CaO peak

Claims (6)

[Claims] 1. A method for producing high-density apatite ceramics, which comprises impregnating apatite powder with an aqueous solution of a water-soluble calcium salt of an organic acid, drying, shaping, and firing. 2. The amount of calcium salt impregnated is C compared to the apatite powder.
2. The method for producing high-density apatite ceramics according to claim 1, wherein the aqueous solution of a water-soluble calcium salt of an organic acid is impregnated in an amount of 0.5% by weight or less in terms of aO. 3. 2. The method for producing high-density apatite ceramics according to claim 1, wherein the water-soluble calcium salt of an organic acid is calcium acetate, calcium oxalate, calcium lactate, calcium tartrate, calcium citrate, or the like. 4. Impregnating an apatite dry compact, dry compact or calcined compact with an aqueous solution of a water-soluble calcium salt of an organic acid,
A method for producing high-density apatite ceramics, which comprises firing after drying. 5. 4. The method for producing high-density apatite ceramics according to claim 3, wherein the apatite molded body is impregnated with an aqueous solution of a water-soluble calcium salt of an organic acid in an amount such that the amount of calcium salt impregnated is 0.5% by weight or less in terms of CaO. 6. 4. The method for producing high-density apatite ceramics according to claim 3, wherein the water-soluble calcium salt of the organic acid is calcium acetate, calcium oxalate, calcium lactate, calcium tartrate, calcium citrate, or the like.