JPS6158425B2 - - Google Patents

Description

[Detailed description of the invention]

β-Tricalcium phosphate (hereinafter abbreviated as β-TCP) is a promising material for artificial bone. One of the important medical requirements for this material is that it should have high strength. Currently, the ones announced in Japan and overseas have a bending strength of 1000 to 14000.
Although the strength is on the order of Kgf/cm ² , the method of the present invention provides a product with a strength far exceeding that. The biggest problem in producing high-strength sintered bodies of β-TCP is the β→α phase transition phenomenon that occurs at 1180°C. This is because the crystal density decreases from 3.07 to 2.87, making it difficult to obtain a high-density product and therefore difficult to obtain a high-strength product. The present invention searched for substances that have the effect of suppressing the phase transition of β-TCP, and through detailed investigation of its effects, discovered the phase transition suppressing effect of silica, and clarified the conditions for its production. The manufacturing method will be described below. 1. Preparation of β-TCP Powder Currently published starting material powders for high-strength β-TCP are based on an aqueous solution precipitation method, but in the method of the present invention, they were synthesized using a dry synthesis method (solid phase reaction method). The manufacturing procedure will be described below. (1) Calcium hydrogen phosphate ( _CaHPO4・
2H ₂ O) is heat-treated at 850°C for 7 hours to produce β-calcium pyrophosphate (β-Ca ₂ P ₂ O ₇ ).
Calcium carbonate (CaCO ₃ ) was added to this at a molar ratio of 1:1 and mixed uniformly.
β-
Obtain TCP synthetic powder. (2) Add 1 to 8% of silica as a phase transition inhibitor to the β-TCP fine powder, and further add β-C ₂ P as a sintering accelerator, and mix thoroughly and uniformly. As the silica, crystalline quartz, amorphous quartz (quartz glass), colloidal silica, or the like is used. This is formed into the desired shape by wet or dry molding, and heated to 1200 to 1250℃.
Sinter at a temperature of Next, we will discuss the test results using this method. Using crystalline quartz as additive silica, β-
The results of sintering TCP powder at 1150-1300℃ and examining the transition from β to α phase are as follows. However, this is an example in which 3% of β-C ₂ P is added as a sintering accelerator.

[Table] As shown in Table 1, 1250℃ for additive-free β-TCP
It almost completely transitions to the α phase. On the other hand, when quartz is added, the amount of α phase produced is extremely low. In particular, addition of 5% shows the best effect. This directly affects the sintered density; in the case of no additives, the maximum density was 2.87 at 1200℃, but
% quartz addition showed a high density of 2.99. In this way, by shifting the phase transition phenomenon of β-TCP to the high temperature side, the sintered density was increased, and as a result, high-strength β-TCP was obtained. The optimum sintering temperature for highly pure β-TCP is 1300~
The optimum sintering temperature is 1350°C, but by adding an appropriate amount of β-C ₂ P, the optimum sintering temperature can be lowered to 1200-1250°C. On the other hand, the effect of suppressing phase transition by adding quartz is 1250℃
Since it is effective in the following temperature range, it is necessary to control the sintering temperature. The sintering promoting effect of β-C ₂ P is due to the formation of a eutectic liquid with β-TCP and the occurrence of liquid phase sintering.
-C ₂ P is a very convenient sintering accelerator because it dissolves in a considerable amount in β-TCP. In the case of Table 1, the bending strength of the β-TCP sintered body obtained by adding 5% quartz and sintering at 1200°C is 1730 kg.
f/cm ² was shown. This far exceeds the conventional level of β-TCP sintered bodies. Although silica used as a phase transition inhibitor may be quartz glass or colloidal silica, it has not been determined that the effect is superior to that of crystalline quartz. Examples are shown below. Example 1 5% of crystalline quartz fine powder and 3% of β-C ₂ P powder were added to β-TCP powder synthesized by the method described above, wet-mixed, and then dried. This powder
A prismatic sample with a length of 70 mm and a cross-sectional area of 6 x 6 mm was press-molded at a molding pressure of 1 ton/cm ² . This was heated in an electric furnace at a rate of 200°C for 1 hour, and when it reached 1200°C, it was held for 1 hour. β obtained under these conditions
- Regarding TCP sintered bodies, bending strength, bulk density,
and the crystal phase and obtained the following results. Water absorption: 0.3% Bending strength: 1730 Kgf/cm ² Bulk density: 2.99 Amount of α phase: 0% Example 2 8% quartz glass fine powder was added to β-TCP powder synthesized by the method described above, β-C ₂ P powder was added at 3% each. The sample was molded in the same manner as in Example 1. The temperature was raised at a rate of 200°C for 1 hour in an electric furnace and held at 1230°C for 1 hour. The properties of the obtained sintered body are shown below. Water absorption rate: 0% Bending strength: 1540Kgf/cm ² Bulk density: 2.94 Amount of α phase: 12%

Claims (1)

[Claims] 1 β-tricalcium phosphate (β-3CaO・
P ₂ O ₅ , β-TCP (abbreviated as β-TCP), 1 to 8% silica (SiO ₂ ) as a phase transition inhibitor, and β-calcium pyrophosphate (β-Ca ₂ P ₂ O ₇ , abbreviated as β-TCP) as a sintering accelerator.
A mixture of 1 to 8% of β-C _{2 P (abbreviated as β-C 2} P) is added and mixed uniformly and molded into a predetermined shape.
β-, which is characterized by sintering in the temperature range of °C.
Method of manufacturing TCP.