JPS6071567A - Manufacture of beta-tricalcium phosphate sintering material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 exhibits high strength. Currently, the bending strength of the products announced both domestically and internationally is around 7,000 to XOOkQf/clt, but the method of the present invention can provide products with a much higher strength.

The biggest problem in producing a high-strength sintered body of β-TCP is the β→α phase transition phenomenon that occurs at /,7go″C. This is because the crystal density is from 3.07 to 2, Since the temperature decreases to 7, it is difficult to obtain a high-density product and therefore a high-strength product is difficult to obtain.

The present invention has searched for substances that have the effect of suppressing the phase transition of β-TCP, and through detailed investigation of its effects, has discovered the phase transition suppressing effect of silica, and has clarified the conditions for its production.

The manufacturing method will be described below.

Z Preparation of β-TCP Powder Currently published starting material powders for high-strength β-TCP are produced by an aqueous solution precipitation method, but in the method of the present invention, they were synthesized by a dry synthesis method (solid phase reaction method). The manufacturing procedure will be described below.

1) Calcium hydrogen phosphate (caHPo4・, 2H2o
) g! Heat treatment is performed at θ°C for 7 hours to produce β-calcium pyrophosphate (β-Ca2P20.). Calcium acetate (CaCO2) was added to this in a molar ratio of /:/ and mixed uniformly. The mixture was heated in a temperature range of /, 000- /: / 00"C for more than 2 hours to form β-T'CP. Obtain synthetic powder.

2) β-'I' CP Silica is added as a phase transition inhibitor in the range of 7 to g% to the fine powder, and β-02P is further added as a sintering accelerator and mixed sufficiently uniformly. As the silica, crystalline quartz, amorphous quartz (quartz glass), colloidal silica, or the like is used. This is made into the desired shape by wet or dry molding, and the size is 1.200~/,
Sinter at a temperature of 230"C.

Next, we will discuss the test results using this method.

Using crystalline quartz as the additive silica, β-TCP powder was sintered at l/, 3-0 to ×300°C, and the state of transition from β to α phase was investigated. The results are as follows. However, this is an example in which 3% of β-02P was added as a sintering accelerator.

Table/ Amount of α-TCP produced (%) As shown in Table/, for additive-free β-TCP, /, 230°
C almost completely transitions to the α phase. On the other hand, when quartz is added, the amount of α phase produced shows a significantly lower density. In this way, the phase transition of β-TCP and the optimal sintering of 1 fft
The temperature can be lowered to 120θ~/, 2jO°C. On the other hand, the effect of suppressing phase transition by adding quartz is
Since it is effective in a grade range of 1 grade or less, it is necessary to control the sintering temperature. This is due to the formation of .beta.-C2P and the occurrence of liquid phase sintering, but the amount of .beta.-C2P is still equivalent to .rho.-TO,P, which far exceeds the conventional level of the hoe body.

Although silica used as a phase transition inhibitor may be quartz glass or colloidal silica, it was not determined that the effect was superior to that of crystalline quartz.

Examples are shown below.

Example/ 1% of crystalline quartz fine powder and 3% of β-C2P powder were added to β-TCP powder synthesized by the method described above, wet-mixed, and then dried. This powder was press-molded into a prismatic sample with a length of 7Qm and a cross-sectional area of B x B at a molding pressure of /lon/aJ. This is heated in an electric furnace for 1 hour, 20 minutes.
The temperature was raised at a rate of 0°C, and when it reached 700°C, it was held for 7 hours. The bending strength, bulk density, and crystal phase of the β-TCP sintered body obtained under these conditions were investigated, and the following results were obtained.

Water absorption rate 203% Bending strength: i 730 kQflo
A bulk density: 2.9 de Amount of α phase: 0% Example 2 To the β-TCP powder synthesized by the method described above, g% of fine silica glass powder and 3% of β-02P powder were added. The sample was molded in the same manner as in Example. The temperature was raised at a rate of 200°C for 7 hours in an electric furnace, and then heated to 230°C for 7 hours.
Holds time. The properties of the obtained sintered body are shown below.

Claims (1)

[Claims] p-! J
2O3, β-TCP), silica (Sl○2) is added as a phase transition inhibitor, and β-TCP is added as a sintering accelerator.
-Calcium pyrophosphate (β-Ca2P207, β-C
2P (abbreviated as 2P) was added at 7-g% and mixed uniformly, molded into a predetermined shape, heated at 200-250°C.
A method for producing β-TCP, characterized by sintering in a temperature range of .