JPH0191865A - Inorganic biomaterial and its manufacture - Google Patents

Abstract

PURPOSE:To provide an intense inorganic biomaterial with an efficient biocompatibility, by dispersing zirconia-alumina ceramics into a specific composition for crystallized glass. CONSTITUTION:An inorganic biomaterial is provided by homogeneously mixing 5-50vol.% zirconia-alumina ceramics with powdery matrix glass, by molding the mixture to a prescribed shape and then by heat-treating the molded object in a temperature range to sinter the object. The powdery matrix glass used includes 12-56wt.% CaO, 1-27wt.% P2O5, 22-50wt.% SiO2, 0-34wt.% MgO, 0-25wt.% Al2O3, each 0-10wt.% K2O, Li2O, Na2O, TiO2, ZrO2, SrO, Nb2O5, Ta2O5 and B2O3 and each 0-5wt.% F2 and Y2O3. The total content of CaO, P2O5, SiO2, MgO and Al2O3 in the matrix glass is 90wt.% or more. The grain size of the matrix glass is less than 200 mesh.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inorganic biomaterial useful as an implant material for artificial bones, artificial tooth roots, etc., and a method for producing the same.

[Prior art and its problems] So-called bioactive ceramics that create chemical bonds with bones include apatite sintered bodies and Na20-K2.
O-Mgo-CaO-3i○2-P205-based crystallized glass is known. Also, MQO-cao-P20s
-8i 02 series glass is crushed to a particle size finer than 200 mesh, the glass powder is molded, and then heat treated in the sintering temperature range of glass powder, and then apatite crystal [Ca10(P○a)s (00,5, F) Crystallized glass produced by heat treatment in a humidity range where 21 and wollastonite crystals [CaS i 03 ] are produced is also known. In this crystallized glass, apatite crystals contribute to biocompatibility, and wollastonite crystals contribute to mechanical strength. Therefore, in order to increase mechanical strength, it is desirable to increase the content of wollastonite crystals. Therefore, crystallized glass is also known in which the content of SiO2 is increased and the amount of precipitated wollastonite crystals is increased.

By the way, the bending strength of these ceramics is 1000 to 1400 kg/l-j for apatite sintered bodies! , N
a20-K2O-MQO-CaO-3i 02-P20
1000-1500Kg/ci with 5M crystallized glass,
MQO-CaO-P205-8 i 02 series crystallized glass is about 1200 to +4008 g/d. Furthermore, CaO-P+ with a large amount of wollastonite precipitated
05-3 i 02 series or CaO-P20s
-8i 02-(MQO, Y20a) type crystallized glass has a high bending strength of 1700 to 2300 Kg/CIi. However, this value is not necessarily sufficient for use as an artificial bone or tooth root, and a material with even higher strength is desired.

Therefore, an object of the present invention is to provide an inorganic biomaterial that has excellent biocompatibility and is even stronger than conventional products.

[Means for Solving the Problems] The present invention has been made to achieve the above-mentioned objects, and includes: CaO 12-56% P2O 51-27% SiO2 2-50% Mqo O-34% Al2O3 0 ~25% K2O 0-10% Li2O0-10% Na2O0-10% Lower i02 0-10% ZrO20-10% SrO0-10% Nb2O50-10% TB2O5 0-10% B203 0-10% F2 0-5% Y203 Contains the above components in the range of 0 to 5%, CaO,, P2O5, Si
This is an inorganic biomaterial with improved mechanical properties by dispersing zirconia-alumina ceramics in crystallized glass having a composition in which the total content of O2, MgO, and Al2O3 is 90% or more.

This inorganic biomaterial consists of apatite crystals and alkaline earth silicate crystals such as wollastonite, diopside, forsterite, okermanite and anorthite.
It contains one or more types, and optionally contains β-tricalcium phosphate crystals [β-Ca3(POa)2].

The n-free biomaterial of the present invention as described above has a medium percentage of CaO 12-56%, P2O 51-27%, SiO2 22-50%, MQO 0-34%, A12O3 0-25%, K2O 0-10%, Li2O 0-10% Na2O 0. ~10% TiO20~10% ZrO20~CoO% SrOO~10% Nb20s 0~10% Ta205
0~10% B2O3 0~10%F2
0-5% Y2 03
Contains the above components in the range of 0 to 5%, Cab, F
205, S i 02 , MQO and Aj2203 (
7) It has a composition in which the total content is 90% or more, and 2
A matrix glass powder having a particle size finer than 0.00 mesh is uniformly mixed with zirconia-alumina ceramics at a volume percentage of 5 to 50%, and after this mixture is molded into a predetermined shape, the temperature at which the molded body is sintered is Heat treatment in the Fl range, in which apatite crystals and one or more alkaline earth silicate crystals selected from wollastonite, diopside, forsterite, okermanite, and anorthite are uniformly precipitated from the glass. It can be manufactured by

In the inorganic biomaterial of the present invention, the reasons for quantitative limitations regarding the composition of the glass serving as the matrix will be described below.

If the CaO content is less than 12%, the sinterability of the glass powder becomes extremely poor, making it impossible to IFI a high-strength crystallized glass. Moreover, when CaO exceeds 56%, the tendency of the glass to devitrify becomes significant. Therefore, the content of CaO is 12-56
limited to %.

When F205 is less than 1%, the glass tends to devitrify significantly,
If it exceeds 27%, the amount of alkaline earth silicate crystals such as wollastonite, diopside, forsterite, okermanite, and anorsite will decrease, so F
The content of 205 is limited to 1-27%. SiO2 is 2
If it is less than 2%, the sinterability of the glass powder will be poor and the amount of alkaline earth silicate crystals precipitated will also be reduced. Also S
When io2 exceeds 50%, the glass tends to devitrify.

Therefore, the content of SiO2 is limited to 22-50%.

MqO is not an essential component, but if it is included, the amount of apatite crystals produced will decrease if it is more than 34%.
Limited to:

Similarly, Al2O3 is not an essential component, but if it is included, 2
If it is more than 5%, the amount of apatite crystals produced will decrease, so it is limited to 25% or less. These five components namely cao, F205, SiO2, MgO and Af20
The total content of 3 is 90% or more for the reason described later.

In the present invention, the matrix glass contains K2O゜Li2O, Na2, which are not harmful to the human body, in addition to the above five components.
O, TiO2, ZrO2, SrO, Nb2O5, Ta2
One or more of 05, B203, F2, and Y203 can be contained within a predetermined amount. If the total amount of these optional components is more than 10%, the amount of apatite crystals and alkaline earth silicate crystals produced may decrease, so it is limited to 10% or less. In addition, if F2 is more than 5%, the glass tends to devitrify, and Y
If 203 is more than 5%, the formation m of apatite crystals and alkaline earth silicate crystals will be reduced, so F2 and Y203 are each limited to 5% or less.

In producing the inorganic biomaterial of the present invention, a mother glass (matrix glass) having the composition range limited above is used.
The powder is first ground to a particle size finer than 200 mesh, mixed uniformly with zirconia-alumina ceramics, and the resulting mixed powder is molded into a desired shape.The molded body is then sintered and then crystallized. It is important to treat it. When the particle size of the mother glass is coarser than 200 mesh, pores tend to remain in the sintered body, making it impossible to obtain a composite crystallized glass with high mechanical strength. In other words, in order to obtain a composite crystallized glass with few pores, uniformly precipitated crystals, and uniform distribution of zirconia-alumina ceramic particles, it is necessary to use a fine mother glass powder with a particle size smaller than 200 mesh. is important. Furthermore, if the volume percentage of the zirconia-alumina ceramics to be composited is less than 5%, it is hardly possible to expect an improvement in mechanical strength due to the composite, and if it is more than 50%, sinterability deteriorates.
Not only cannot an improvement in mechanical strength be expected, but also the biocompatibility of crystallized glass cannot be fully utilized. Therefore,
The blending amount of zirconia-alumina ceramics is limited to 5 to 50% by volume of the base glass.

According to the method for producing inorganic biomaterials of the present invention, mother glass powder with a particle size finer than 200 mesh and zirconia-alumina ceramics are mixed by any known means, and then the molded body is made of the glass/zirconia-alumina ceramics. Heat treatment is performed at the sintering temperature of the ceramic mixed powder in the RFI range, and in a humidity range where apatite crystals and alkaline earth silica PIi salt crystals precipitate. The former heat treatment produces composite crystallized glass with low porosity and high mechanical strength. I
The latter heat treatment is important for precipitating apatite crystals and alkaline earth silicate crystals from the glass.

The sintering humidity range can be determined by heating a molded body of glass/zirconia-alumina ceramic mixed powder at a constant rate and measuring the thermal contraction during the heating. The sintering temperature range is from the start temperature to the end temperature of thermal contraction.

Further, the precipitation temperature range of apatite crystals and alkaline earth silicate crystals is determined by differential thermal analysis of a glass/zirconia-alumina ceramic mixture. By diffracting the X-ray diffraction data of the glass/zirconia-alumina ceramic mixed powder heat-treated at the temperature of the exothermic peak in the differential thermal analysis curve, the precipitated crystals corresponding to each exothermic peak were identified, and the exothermic temperature was determined from the exothermic temperature. The temperature range up to the end temperature is defined as the precipitation temperature range of each crystal.

Any known method may be used as the heat treatment method, but if the hot press method or HIP (hot isostatic pressing) method is used, sintering will be further promoted, pores will be reduced, and the material will have greater mechanical strength. can get.

Zirconia-alumina ceramics mixed with the mother glass usually contains a small amount of Y2O3, CaO1MgOSCe02
Stress-induced deformation fm(
It is made by strengthening alumina using the mantenside transformation (mantenside transformation), and is a ceramic with extremely high strength and high toughness. The preferred ratio of zirconia and alumina in the zirconia-alumina ceramic is 90:10 to 10:90, but a material with higher strength and toughness can be obtained by making the zirconia content higher than the alumina content. For example, 2
Tetragonal zirconia with moz% of Y203 in solid solution and α
- Mix alumina in a weight ratio of 4:1 and heat at 1500℃.
When sintered using the IP method, the bending strength is 20,000 to 24
000 K9/C! A. High strength and high toughness ceramics with a fracture toughness value KIG of 1108N can be obtained. Furthermore, even when the ratio of tetragonal zirconia to α-alumina is 3=2, equivalent mechanical properties are exhibited. The strength of the inorganic biomaterial of the present invention is improved by using these zirconia-alumina ceramics as a reinforcing agent.

The reason why the matrix material is strengthened by the combination of zirconia-alumina ceramics is that the main crack propagates by deflecting around the high-strength, high-toughness zirconia-alumina ceramic particles dispersed in the crystallized glass. This is because greater energy is required for destruction. However, the particle size of the zirconia-alumina ceramic powder to be mixed is preferably finer than 200 mesh. If the zirconia-alumina ceramic powder has a particle size coarser than 200 mesh, pores tend to remain in the sintered body, making it impossible to obtain a composite crystallized glass with high mechanical strength. In other words, in order to obtain composite crystallized glass with fewer pores and uniform crystal distribution, it is necessary to use fine glass powder with a particle size finer than 200 mesh and zirconia-alumina ceramic fine powder with a particle size finer than 200 mesh. is desirable.

[Example] Using oxides, carbonates, phosphates, hydrates, fluorides, etc. as raw materials, a batch of matrix glass corresponding to the composition shown in Table 1 was prepared, and this was placed in a platinum crucible. te1
It was melted at 450-1550°C for 2 hours. Next, the melt was poured into water and rapidly cooled, and after drying, it was put into a ball mill and heated for 20 minutes.
It was ground to a particle size of 500 mesh or less (500 mesh). Next, a zirconia-alumina ceramic powder (particle size: 300 mesh) was obtained by mixing square zirconia and α-alumina in the composition (wt%) shown in Table 1 and firing.
were added in the amounts shown in Table 1, wet mixed using a ball mill for several hours, and then dried. The resulting mixture was placed in a graphite mold and heated at a constant gastric temperature rate of 3°C/min from room temperature to 1150°C for 7j while applying a pressure of 300 kg/d.
The molded body was heated and held at 1150° C. for 2 hours to sinter and crystallize the molded body.

Thereafter, it was cooled to room temperature in a furnace to obtain a composite crystallized glass with zirconia-alumina ceramics.

When the fractured surfaces of each of the composite crystallized glasses produced in this way were observed with a scanning electron microscope (SEM), they all had dense structures with almost no pores. Furthermore, these composite crystallized glasses were crushed and the precipitated crystal phase was identified by powder xi diffraction. Further, the composite crystallized glass was processed into a round bar with a diameter of 3 to 5all using a No. 300 diamond grindstone, and a three-point bending strength test was conducted. Glass composition, composition of zirconia-alumina ceramics, blending amount of ziconia-alumina ceramics (volume percentage relative to glass)
Table 1 shows the precipitated crystal phase and three-point bending strength. As is clear from the table, the inorganic biomaterial of the present invention has a
It has a high bending strength of 800Kg/-.

[Effects of the Invention] The inorganic biomaterial of the present invention contains CaO and P20s, which are necessary for chemically bonding with bone, and also uses zirconia-alumina ceramics as a reinforcing agent.
00-3800? Since it has a very high bending strength of rg/d, it is extremely useful as a biomaterial for artificial bones and artificial tooth roots.

Claims (2)

[Claims] (1) In weight percentage: CaO 12-56% P_2O_5 1-27% SiO_2 22-50% MgO 0-34% Al_2O_3 0-25% K_2O 0-10% Li_2O 0-10% Na_2O 0-10% TiO_2 0-10 % ZrO_2 0-10% SrO 0-10% Nb_2O_5 0-10% Ta_2O_5 0-10% B_2O_3 0-10% F_2 0-5% Y_2O_3 0-5% Contains the above components in the range of CaO, P_2O_5, S
The total content of iO_2, MgO and Al_2O_3 is 9
An inorganic biomaterial consisting of a ceramic composite crystallized glass in which zirconia-alumina ceramics are dispersed in a crystallized glass having a composition of 0% or more. (2) In weight percentage: CaO 12-56% P_2O_5 1-27% SiO_2 22-50% MgO 0-34% Al_2O_3 0-25% K_2O 0-10% Li_2O 0-10% Na_2O 0-10% TiO_2 0-10 % ZrO_2 0-10% SrO 0-10% Nb_2O_5 0-10% Ta_2O_5 0-10% B_2O_3 0-10% F_2 0-5% Y_2O_3 0-5% Contains the above components in the range of CaO, P_2O_5, S
The total content of iO_2, MgO and Al_2O_3 is 9
A matrix glass powder having a composition of 0% or more and a particle size finer than 200 mesh is mixed with zirconia-alumina ceramics at a volume percentage of 5 to 50%.
After mixing the mixture uniformly and molding this mixture into a predetermined shape, the molded body is heat-treated in a temperature range where it sinters to produce apatite crystals from glass, wollastonite, diopside,
1. A method for producing an inorganic biomaterial, which comprises performing heat treatment in a temperature range at which one or more alkaline earth silicate crystals selected from forsterite, okermanai, and anorsite are uniformly precipitated.