JPH02217366A - Whisker composite sintered body and its production - Google Patents

Abstract

PURPOSE:To obtain whisker-composite sintered body of high stability, high strength and toughness by firing calcium fluorophosphate together with calcium oxide component or alumina component as well as silica component. CONSTITUTION:Calcium fluorophosphate is mixed with a needed amount of a silica component, a needed amount of calcium oxide component or a needed amount of alumina component. Then, the mixture is fired at 800 to 1,600 deg.C to give the subject composite sintered product. Calcium fluorophosphate is used usually in a powder form of 0.1 to 1000mu particle sizes. As a silica component, calcium oxide component, alumina component, and magnesia component, are used silica, calcium oxide, alumina and magnesia as well as compounds which can be converted into these substances, such carbonates, bicarbonates, hydroxides or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel whisker composite sintered body and a method for manufacturing the same. More specifically, the present invention
The present invention relates to a sintered body suitable as a material for artificial bones and artificial tooth roots, which has a matrix of crystalline calcium fluorophosphate with excellent biocompatibility and is reinforced by dispersing inorganic whiskers, and a method for manufacturing the same from various raw materials.

Conventional technology Calcium phosphate compounds such as hydroxyapatite and tricalcium phosphate are non-toxic, and their sintered bodies easily integrate with bone in vivo, and they gradually disappear and are easily replaced by new bone. Therefore, it is used as a substitute material for biological hard tissues such as artificial bones and artificial tooth roots. However, this calcium phosphate compound sintered body lacks mechanical strength and toughness, so it is necessary to mold it into a shape that fits the defect area. When implanted or implanted in a living body, it may chip or break, and is not necessarily satisfactory in practice.

Examples of ways to improve these defects include apatite made into fibers or needles and further reinforced with mineral fiber materials (Japanese Patent Laid-Open No. 59-57971), and mullite whiskers made from tricalcium phosphate or other materials. Compositely strengthened by precipitating apatite at the same time during firing (Japanese Unexamined Patent Publication No. 62
-162676) has been proposed.

However, in the former case, it is very difficult to obtain fibrous or acicular apatite, and when a mineral fiber material that has an affinity for apatite is mixed with an apatite component and fired, the mineral fiber material becomes A problem arises in that the reaction between the apatite component and the apatite component causes a compositional shift, resulting in distortion and strength deterioration.

On the other hand, in the latter case, although mullite whisker formation requires a firing temperature of 1,300°C or higher, hydroxyapatite is produced by a normal wet method, and its suitable firing temperature is 1,000 to 1,300°C. At higher temperatures, abnormal grain growth occurs, making it impossible to obtain a good quality composite.
In addition, the large amount of alumina contained in mullite does not cause undesirable effects such as converting hydroxyapatite to tricalcium phosphate and converting β-tricalcium phosphate to a-tricalcium phosphate. This is not necessarily a satisfactory result.

On the other hand, the present inventors previously precipitated anorthite and diopside whiskers simultaneously with tricalcium phosphate and hydroxyapatite to strengthen them in a composite manner (Japanese Patent Application No. 63-164959, Patent application 16496/1983
Specification No. 0) was proposed.

However, even with these materials, hydroxyapatite is converted into a-tricalcium phosphate and β-
β-tricalcium phosphate tends to convert into α-tricalcium phosphate,
However, the transformation from apatite to β-tricalcium phosphate and from β-tricalcium phosphate to a-tricalcium phosphate involves contraction and expansion, as shown here.
Distortion may occur, and strict control of manufacturing conditions is required to prevent this.

Problems to be Solved by the Invention The present invention overcomes the drawbacks of the conventional whisker composite calcium phosphate sintered bodies, and produces stable, high-strength, and high-strength sintered bodies that do not undergo the aforementioned transition even when fired. This was done for the purpose of providing a new whisker composite sintered body with high toughness.

Means for Solving the Problems As a result of extensive research by the present inventors in order to obtain a high-strength, high-toughness sintered body that is strengthened by whiskers and does not suffer from distortion due to contraction or expansion during the production process, the present inventors have found that: Calcining a mixture of calcium fluorophosphate and inorganic whiskers or
By firing a mixture containing calcium oxide or alumina together with silica, or at least one selected from alumina and magnesia together with silica and calcium oxide, or a required amount of supply components of these oxides, It has been discovered that at the same time as crystalline calcium fluorophosphate is produced, inorganic whiskers are uniformly dispersed therein, forming a composite of the two, and based on this finding, the present invention has been accomplished.

That is, the present invention provides a whisker composite sintered body comprising a matrix mainly composed of crystalline calcium fluorophosphate and inorganic whiskers dispersed therein.

One of the methods for producing a composite sintered body of the present invention is to add calcium fluorophosphate together with a required amount of silica supply component.
Add the required amount of calcium oxide feed component or the required amount of alumina feed component, or add the required amount of alumina feed component and the required amount of magnesia feed component together with the required amount of silica feed component and the required amount of calcium oxide feed component. At least one selected from the following is added, and the mixture is then fired at a temperature of 800 to 1600°C.

At this time, the raw materials are calcium fluorophosphate,
It is usually used in powder form of about 0.1"101000p.

Next, the silica supply component, calcium oxide supply component, alumina supply component, and magnesia supply component include silica, calcium oxide, alumina, and magnesia, as well as substances that can be converted into these compounds under firing conditions, such as carbonate and bicarbonate. Salts, hydroxides, etc. are used. These ingredients are
It is used in the form of powder, granules, slurry, aqueous solution, etc.

The usage ratio of these components to calcium fluorophosphate is 0.05 to 40% by weight of the silica supply component in terms of Sin, and 105 to 20% by weight of the calcium oxide supply component in terms of CaO, or 0.05 to 20% in terms of Aff, 03.
% by weight of alumina feed component or with 0.05-40 wt. % silica feed component calculated as Si islands and 0.05-20 wt. % calcium oxide feed component calculated as CaO, 0.05 wt. It is preferable to use at least one selected from the group consisting of 20% by weight of an alumina supply component and 0.05 to 20% by weight of a magnesia supply component in terms of M90. The ratio of these components used is preferably 1 to 1 mol of silica per 1 mol of calcium oxide.
4 mol, alumina 0゜5~3 mol, magnesia 0.5~
It is selected to be in the range of 3 moles.

In this case, instead of adding each feed component individually, they are added as a nosite component, a diogsite component corresponding to the composition formula CaO・2~2.53iO8・0.8~1.2Mgo, etc. You can also do that.

Another method for producing the composite sintered body of the present invention is carried out by mixing calcium fluorophosphate and inorganic whiskers, and then firing the mixture at a temperature of 800-1600°C.

By such a method, a composite sintered body consisting of calcium fluorophosphate and inorganic whiskers is obtained, and the blending ratio of both is preferably 60 to 60% calcium fluorophosphate.
98% by weight, and inorganic whiskers range from 2 to 40% by weight.

In addition, if anorthite whiskers are to be produced, this sintered body contains a small amount of wollastonite, akermanite, mullite, etc., which are by-products during firing, in addition to anorthite, and if diopside whiskers are to be produced, In addition to diopside, it contains small amounts of forsterite and wollastonite, which are by-products during firing.

Calcium fluorophosphate forming a matrix in this composite sintered body exists as a crystal, and inorganic whiskers exist in a dispersed state in this matrix. Furthermore, when using various oxide-supplying components, components that do not participate in the formation of whiskers are usually mixed in the matrix.

This whisker usually has a major axis of 0.5 to 2000 μm1
Preferably l-100μ foot, minor axis 0.2-100μm,
Preferably 0.5 to 50 μm, aspect ratio 2 to 20,
Preferably it has 5-15.

Next, one specific embodiment for manufacturing a composite sintered body according to the method of the present invention will be described. Calcium fluorophosphate powder or granules are used as a raw material, and together with a predetermined amount of silica and calcium oxide, A predetermined amount of at least one selected from alumina and magnesia is added in powder or granule form and thoroughly mixed. In this case, as described above, instead of the raw material oxide, one that can be converted into these components under the firing conditions may be used, or the composition formula Ca0 ・0.5-2.5SiO* "0.2 ~l
-5A (hos anorthite and compositional formula Ca0.2-2
．． 53iO1・0.8-1.2Mg.

It may also be added as diopside. When using granular raw materials, it is preferable to crush them using a vibrating mill or the like.

The powdery mixture thus prepared is molded into a desired shape by a conventional method such as a press molding method or a slip casting method, dried, and then fired at a temperature in the range of 800 to 1600°C. Firing time is usually 0.1-10 hours.

By this firing, crystalline calcium fluorophosphate and inorganic whiskers are simultaneously generated, and a composite sintered body in which the latter is dispersed and contained in the matrix of the former is obtained.

In the method of the present invention, it is preferable to select the mixing ratio of the inorganic whiskers and the raw material components so that the content of the inorganic whiskers in the composite sintered body is within the range of 2 to 40% by weight.

Effects of the Invention The sintered body of the present invention has good biocompatibility, and calcium fluorophosphate undergoes transition to β-tricalcium phosphate and a-tricalcium phosphate when fired with additives, as in the past. It has excellent mechanical strength and toughness, and when used as an artificial tooth root, it has excellent tactility and acid resistance. Become.

Furthermore, in the method of the present invention, the bond between the whiskers and the matrix in the sintered body can be strengthened,
Moreover, since inorganic whiskers and additive components do not dissolve, substitute, or invade into calcium fluorophosphate during firing, the composition does not change even after firing, and the whisker content can be easily adjusted.

Therefore, the composite sintered body of the present invention is suitable as a material for artificial bones and artificial tooth roots, especially artificial tooth roots, for treatment in fields such as orthopedics, oral surgery, and dentistry.

Example Next, the present invention will be explained in more detail with reference to Examples.

Reference Example 1 (Acid resistance test of calcium fluorophosphate and hydroxyapatite) 10 test pieces each of calcium fluorophosphate and hydroxyapatite in the shape of a 4X2X2m shoulder block were placed in a 200t 12 volume lactic acid buffer tank (lactic acid buffer: Genuine-
An acid resistance test was conducted for 24 hours while stirring the sample in a 50% sodium lactate solution. When we measured the amount of weight loss per surface area before and after the test, we found that
Hydroxyapatite has a large weight loss of 16.5% and has poor acid resistance, while calcium fluorophosphate has a weight loss of 2.3%.
The weight loss was small and the acid resistance was excellent.

Example 11 Comparative Example 1 Adding 2 parts of anorthite powder to calcium fluorophosphate powder
After adding 0% by weight and thoroughly mixing, it was fired at 1350° C. for 2 hours to produce an anorthite whisker composite sintered body, which was molded into a block-like body of 4×2×2 mm. The test piece thus obtained was prepared using 200Ila adjusted to pH 4.
lactic acid buffer tank (lactic acid buffer: pure-grade lactic acid and 50%
A 24-hour acid resistance test was carried out by placing the sample in a liquid mixture with a sodium lactate solution and stirring. For comparison, a test piece obtained in the same manner as above except that hydroxyapatite was used instead of calcium fluorophosphate was subjected to an acid resistance test in the same manner as above. When we measured the amount of weight loss per surface area before and after the test, the weight loss was large at 78.8% for the product using hydroxyapatite as the raw material, and it was inferior in acid resistance, whereas the product using calcium fluorophosphate as the raw material had a large weight loss of 78.8%. There are 7 things
．． The weight loss was small at 0%, and the acid resistance was excellent.

Example 2, Comparative Example 2 Calcium fluorophosphate powder was added with 5% by weight of CaO powder and A2.0. 7% by weight of powder and Si
After adding 12% by weight of granules and mixing thoroughly, 3009 ml of water was added to this mixture 10h, and 12% by weight of zirconia media was added.
The mixture was placed in a vibrating mill with AI9, mixed and ground for 60 minutes, filtered, and the solid was dried at 110° C. for 60 minutes.

Next, the material was passed through a 110-mesh sieve and then press-molded in a mold (40 x 50 x I 0 ml) at a molding pressure of 300 kg/c112, and the obtained molded product was divided into two parts and heated at 1200°C and 1300°C, respectively. It was baked for 2 hours. A sample (3 x 4 x 36 mm) was prepared from the two types of anorthite whisker composite sintered bodies thus obtained, and its bending strength (MPa) was measured. As a result, the bending strength was 130 MPa (relative density 95.0%) for the one fired at 1200°C, and 220 MPa for the one fired at 1300°C.
(relative density 99.7%).

For comparison, the bending strength (MPa) of a sample obtained in the same manner as above except that hydroxyapatite was used instead of calcium fluorophosphate was measured. As a result, the bending strength of the one fired at 1200℃ was 100MPa (relative density 96
．． 0%), and the one fired at 1300°C had a relative density of 150 MPa (99.5% relative density).

These results show that the product of the present invention has better bending strength.

Furthermore, in the comparative product, transfer of hydroxyapatite to a-tricalcium phosphate was observed.

Example 3, Comparative Example 3 To the calcium fluorophosphate powder, based on the powder, 4% by weight of CaO powder, 4% by weight of Mgo powder, and Sin,
After adding 12% by weight of grains, a sintered body was obtained in the same manner as in Example 2. Samples (3×4
36 mm) was prepared, and its bending strength (MPa) was measured. As a result, the bending strength of the one fired at 1200℃ was 1
40 MPa (relative density 94.0%), and the one fired at 1300°C was 200 MPa (relative density 99.1%).

For comparison, the bending strength (MPa) of a sample obtained in the same manner as above except that hydroxyapatite was used instead of calcium fluorophosphate was measured. As a result, the bending strength of the one fired at 1200℃ was 130MPa (relative density 94
．． 0%), and the one calcined at 1300°C was 180 MPa (relative density 99.0%).

These results show that the product of the present invention has better bending strength.

Furthermore, in the comparative product, transfer of hydroxyapatite to β-tricalcium phosphate was observed.

Claims (1)

[Scope of Claims] 1. A whisker composite sintered body comprising a matrix mainly composed of crystalline calcium fluorophosphate and inorganic whiskers dispersed therein. 2 The inorganic whiskers have a major axis of 0.5 to 2000 μm,
The whisker composite sintered body according to claim 1, wherein the whisker composite sintered body has a minor axis of 0.2 to 100 μm and an aspect ratio of 2 to 20. 3. The whisker composite sintered body according to claim 1 or 2, wherein the content of inorganic whiskers is within the range of 2 to 40% by weight. 4. A claim characterized in that, together with the required amount of silica-supplying component, the required amount of calcium oxide-supplying component or the required amount of alumina-supplying component is added to calcium fluorophosphate, and then this mixture is calcined at a temperature of 800 to 1600 °C. Item 3. A method for producing a whisker composite sintered body according to Item 1, 2 or 3. 5. The method for producing a whisker composite sintered body according to claim 4, wherein the respective supply components are added so that the content of inorganic whiskers formed by firing is within the range of 2 to 40% by weight. 6 To calcium fluorophosphate, add at least one selected from the required amount of silica supply component and the required amount of calcium oxide supply component, the required amount of alumina supply component and the required amount of magnesia supply component, and then add this mixture. The method for producing a whisker composite sintered body according to claim 1, 2 or 3, wherein the whisker composite sintered body is fired at a temperature of 800 to 1600°C. 7 The silica supply component, the alumina supply component and the calcium oxide supply component are combined with the composition formula CaO・0.5~2.5SiO_2・0.2~1.5A
The method for producing a whisker composite sintered body according to claim 6, wherein l_2O_3 is added as anorthite. 8 The silica supply component, the alumina supply component and the magnesium oxide supply component are combined with the composition formula CaO・2~2.5SiO_2・0.8~1.2MgO
The method for producing a whisker composite sintered body according to claim 6, wherein the whisker composite sintered body is added as diopsite. 9. The method for producing a whisker composite sintered body according to claim 6, 7 or 8, wherein each of the supplied components is added so that the content of inorganic whiskers formed by firing is within the range of 2 to 40% by weight. 10. The method for producing a whisker composite sintered body according to claim 1, 2 or 3, characterized in that calcium fluorophosphate and inorganic whiskers are mixed and then this mixture is fired at a temperature of 800 to 1600°C.