JPH0477683B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing hydroxyapatite powder in which a zirconium compound is dispersed, and more particularly, to a method for producing hydroxyapatite powder in which a zirconium compound is dispersed, which is a raw material for a sintered body of hydroxyapatite in which a zirconia is dispersed and has high strength and toughness. The present invention relates to a method for easily and continuously manufacturing a body. [Prior art and its problems] Hydroxyapatite, which has a composition of Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , is the main component of minerals in bones and teeth of vertebrates, so when it is implanted in a living body, It is known as a material with extremely high biocompatibility, such as direct bonding with bone, and its sintered body is currently attracting attention as an implant material in the fields of orthopedics and dentistry. However, hydroxyapatite obtained by conventional methods and sintered at high temperatures without being decomposed has excellent compatibility with bone, but has a drawback in mechanical properties. In other words, it has enough compression strength to be put to practical use as an artificial tooth root material, but has low fracture toughness, which is a measure of resistance to tension, bending, and impact, and can be put to practical use as an artificial bone material. has not yet been reached. Methods to improve the strength of hydroxyapatite sintered bodies include hot pressing and HIP (hot pressing).
High-pressure sintering methods using an isostatic press, etc., methods for strengthening sintered bodies by adding whiskers, methods for strengthening sintered bodies by adding metal oxides, etc. have been proposed. However, although the high-pressure sintering method or the method of strengthening the sintered compact by adding metal oxides, etc., increases the strength, it has the disadvantage of not being able to increase the toughness. Instead, the whisker becomes a defect,
As a result, there is a problem that a product with high strength and high toughness cannot be obtained. On the other hand, the present inventors have already discovered a method of dispersing zirconia to increase strength and toughness by wet-mixing hydroxyapatite powder and zirconia powder, drying the resulting mixture, and hot-pressing it. We proposed a method to obtain a zirconia-dispersed hydroxyapatite sintered body by sintering (patent application 1983).
-152819, Japanese Unexamined Patent Publication No. 11561/1983). However, the bending strength of the hydroxyapatite sintered body obtained by this method decreases as the amount of zirconia added increases. Further, in this method, a sintered body with desired strength cannot be obtained unless sintered at high pressure and high temperature. The present invention has been made in view of the problems of the prior art described above, and it is possible to easily and continuously produce hydroxyapatite powder dispersed in a zirconium compound, which is a raw material for a zirconia-dispersed hydroxyapatite sintered body having high strength and high toughness. The purpose is to provide a method for manufacturing. [Means for solving the problem] In line with the above objectives, the present inventors have developed high strength,
As a result of repeated research into methods for uniformly dispersing zirconia fine particles in hydroxyapatite sintered bodies to achieve high toughness, we found that hydroxyapatite slurry and zirconium compound slurry are mixed in the presence of an alkali, or hydroxyapatite is When zirconia or a zirconium salt or zirconia hydrate serving as a zirconia source is added and reacted at the same time as the introduction of raw materials for hydroxyapatite during production, these zirconium compounds are uniformly dispersed in the form of fine particles in hydroxyapatite. The zirconium compound-dispersed hydroxyapatite powder is calcined, molded,
The inventors discovered that sintering produces a hydroxyapatite sintered body in which fine zirconia particles are uniformly dispersed, and the present invention was achieved based on this finding. That is, in the method for producing zirconium-dispersed hydroxyapatite powder of the present invention, a zirconium compound, an alkaline solution, and hydroxy It is characterized in that an apatite slurry or a calcium salt solution and a phosphate solution, which are raw materials for hydroxyapatite, are introduced, mixed and reacted, and the obtained precipitate is continuously discharged from the outlet. In the first aspect of the present invention, a calcium salt solution, a phosphate solution, and an alkaline solution, which are raw materials for hydroxyapatite, and in addition, zirconia or a zirconium salt or zirconia hydrate, which is a zirconia source, are mixed in a predetermined manner. By simultaneously introducing these into a solution mixer, mixing them, and causing a reaction, it is possible to efficiently obtain hydroxyapatite powder in which fine particulate zirconium compounds are uniformly dispersed. In the second aspect of the present invention, a hydroxyapatite slurry in which hydroxyapatite powder is dispersed in water, an alkaline solution, and a zirconium compound are simultaneously introduced into a predetermined solution mixer, and when these are mixed, the presence of an alkali is detected. As a result, a hydroxyapatite powder in which fine particulate zirconium compounds are uniformly dispersed can be obtained. In this case, the zirconium compound can also be dispersed in water and introduced as a slurry. Examples of the calcium salt used in the present invention include salts such as calcium nitrate, calcium chloride, calcium formate, and calcium acetate. Some calcium salts contain other metal salts (Pb, Ba,
By mixing salts of Sr, Cd, Zn, Ni, Mg, Na, K, and Al, reaction products with various properties can be obtained. As the phosphate used in the present invention,
Examples include primary ammonium phosphate, secondary ammonium phosphate, and tertiary ammonium phosphate. In addition, the alkaline solution is appropriately selected depending on the type of calcium salt or phosphate;
Aqueous ammonia, ammonium bicarbonate solution, sodium carbonate solution, or a mixed solution thereof may be used as appropriate. In the present invention, as the zirconium compound, zirconium oxide (zirconia), zirconia hydrate, or a zirconium salt that is oxidized to zirconia during calcination or sintering is used. The zirconia used here includes high-purity zirconia (single crystal zirconia), Y ₂ O ₃ , CaO
Partially stabilized zirconia stabilized with etc. can be mentioned. As the zirconium salt, zirconyl nitrate (ZrO(NO ₃ ) ₂ ), zirconium oxychloride (ZrOCl ₂ ), etc. can be preferably used. The zirconium compound used here preferably has a zirconia content of 1 mol% to 1 mol% in the sintered body after sintering.
Add so that the amount becomes 94 mol% (0.06 vol% to 50 vol%). That is, since the physical properties of the sintered body change depending on the zirconia content, the zirconia content is appropriately adjusted depending on the site where the obtained sintered body is to be used in a living body. However, the zirconia content is 1 mol%
If the content is less than 94 mol %, the effect of zirconia on the sintered body will be small, and if the content exceeds 94 mol %, the biocompatibility as a biomaterial will decrease, although it will contribute to high strength. These raw materials are introduced into the solution mixer through a plurality of inlets, for example as an aqueous solution. However, zirconia and zirconia hydrate are introduced as a slurry dispersed in water. When these raw materials are introduced from a plurality of inlets, they may be introduced from separate inlets, or two or more types of raw materials may be introduced from the same inlet. For example, zirconia particles or zirconia hydrate slurry can be introduced dispersed in a calcium salt solution, phosphate solution, or alkaline solution. Here, the zirconia hydrate slurry refers to a hydrate slurry typified by zirconium hydroxide obtained from zirconyl nitrate or zirconium oxychloride. Zirconia particles are commercially available high-purity ZrO ₂ , partially stabilized with Y ₂ O ₃ or CaO.
Refers to ZrO ₂ or ZrO ₂ obtained by drying and calcining zirconia hydrate. Note that it is not preferable to introduce the zirconium salt and the phosphate solution through the same inlet, since this will cause precipitation of zirconium hydrogen phosphate. The preferred combinations are as follows. Alkaline solution with zirconia particles suspended,
When introducing calcium salt solution and phosphate solution from different inlets, a mixed solution of zirconium salt and calcium salt,
When a phosphate solution and an alkaline solution are introduced from different inlets; When a zirconia slurry, a hydroxyapatite slurry, and an alkaline solution are introduced from different inlets. When the raw materials are introduced into the solution mixer as described above, mixing and reaction occur in a relatively short time at the confluence point in the solution mixer, and the resulting precipitate (reaction product) is continuously drawn out from the outlet. can do. Here, a mixing method using the solution mixer described above will be explained with reference to the drawings. FIGS. 1 and 2 are schematic diagrams showing an example of the method for producing hydroxyapatite powder of the present invention, in which 1 is a solution mixer, 2a to 2c are inlets, and 3 is an outlet. show. In FIG. 1, according to a preferred embodiment of the present invention, the alkaline solution is introduced from the inlet 2a of the solution mixer 1, the phosphate solution is introduced from the inlet 2b, and the mixed solution of zirconium salt and calcium salt is introduced from the inlet 2b. They are introduced simultaneously from the inlet 2c and adjusted so that they react simultaneously and efficiently. FIG. 2 shows a solution mixer that can be used, for example, when an alkaline solution is mixed in advance with a phosphate solution. That is, in this case, a mixed solution of a phosphate solution and an alkaline solution is simultaneously introduced into the inlet 2a, and a mixed solution of a zirconium salt and a calcium salt is simultaneously introduced into the inlet 2b. In this way, the solution mixer 1 used in the present invention is
Although it has a plurality of inlets 2 and one outlet 3,
Its shape is not particularly limited, and any shape may be adopted in consideration of the order of addition of the alkaline solution, calcium salt solution, phosphate solution, zirconium compound, dilution rate, flow rate, etc. In addition, if a baffle plate, glass filter, slit, etc. is installed at the place where raw materials such as alkaline solution and calcium salt solution join in the solution mixer 1 to create turbulent flow, raw materials such as alkaline solution and calcium salt solution can be mixed. can be mixed efficiently, and the shape of the solution mixer 1 can be made compact. In the present invention, the solution mixer as described above is used, and the dilution rate, concentration, flow rate, etc. of the alkaline solution, calcium salt, phosphate, or zirconium salt solution are adjusted and the set conditions are maintained. Therefore, regardless of the scale of production, a precipitate with a desired composition (a coprecipitate or a mixture of a zirconium compound and hydroxyapatite) can be obtained. For example, a mixed aqueous solution of calcium salts and zirconium salts and a phosphate solution are adjusted so that Ca/P = 1.67, mixed in a flow of an alkaline solution with an appropriately adjusted concentration, and then The mixture is introduced into a receptor or directly into a filter for filtration to continuously obtain a coprecipitate of hydroxyapatite and zirconium hydroxide with Ca/P=1.67. In addition, in the present invention, not only the composition of Ca/P = 1.67 but also the concentration of alkaline solution or By adjusting the flow rate, it is possible to arbitrarily and easily change the Ca/P ratio within the range of 1.5 to 1.95 depending on the purpose. When zirconia is used as the zirconium compound, a mixture in which zirconia is uniformly dispersed in hydroxyapatite, which is a reaction product, is obtained. The coprecipitate or mixture of the zirconium compound and hydroxyapatite obtained as described above is washed if necessary and dried to obtain the zirconium compound-dispersed hydroxyapatite powder of the present invention. Furthermore, the hydroxyapatite powder of the present invention can be calcined,
By molding and sintering, a zirconia-dispersed hydroxyapatite sintered body with high strength and high toughness is obtained. Here, when processing the hydroxyapatite powder of the present invention, there is an advantage that a product with high strength and high toughness can be obtained even if calcination and sintering are performed under extremely mild conditions. for example,
Calcining can be carried out at a relatively low temperature of 200 to 900°C, and sintering is usually performed at a pressure of 50 to 400 Kg/cm ² and a temperature of
Sintering is carried out at a temperature of 500 to 1,500°C, but sintering can also be performed at normal pressure if the temperature is set to 1,000°C or higher. Of course, by sintering by hot pressing, HIP, etc., a hydroxyapatite sintered body with high strength and high toughness can be obtained at a lower temperature. The zirconia-dispersed hydroxyapatite sintered body obtained by sintering the hydroxyapatite powder of the present invention in this way is suitable for applications that require homogeneous properties as a biological material, etc. is suitably used as a dental artificial tooth root, an artificial jaw bone, an orthopedic artificial bone, an adsorbent in the form of spherical fine particles, and the like. [Examples] Hereinafter, the present invention will be explained in more detail based on Examples. Example 1 Zirconium hydroxide-dispersed hydroxyapatite powder was produced using the solution mixer 1 shown in FIG. 1, and a zirconia-dispersed hydroxyapatite sintered body was produced using this powder as a raw material. First, as an alkaline solution, 1125 ml of A solution containing 1.3 mol of ammonia, sulfuric ammonium phosphate,
B solution 2250 containing 0.9 mol and 0.3 mol ammonia
ml, calcium nitrate 1.5 mol and zirconyl nitrate
2250 ml of C solution containing 0.04 mol of each were prepared. These solutions A, B, and C were fed at 45°C from inlets 2a, 2b, and 2c of the solution mixer 1 shown in
The mixture was continuously introduced for 30 minutes to obtain a coprecipitate. This coprecipitate was introduced onto a filter in parallel with the reaction and filtered, and after repeated washing and filtration,
The mixture was dried with hot air at 100 to 120°C, and then pulverized using a pulverizer to obtain hydroxyapatite powder in which zirconium hydroxide was dispersed. The powder obtained in this way was heated to 900°C in the atmosphere.
The material was calcined for 1 hour to obtain a raw material for sintering, and after molding, it was sintered at normal pressure at 1300°C to obtain a zirconia-dispersed hydroxyapatite sintered body. In order to investigate the mechanical properties of the obtained sintered body,
Bending strength, elastic modulus and fracture toughness were measured. The results are shown in Table 1. Note that the zirconium hydroxide in the coprecipitate had become zirconia at the stage of calcination, and the content of zirconium oxide in the sintered body was 20 mol%. Example 2 The content of ammonia in solution B was set to 0.5 mol,
The content of zirconyl nitrate in the C solution was set to 0.2 mol,
A zirconia-dispersed hydroxyapatite sintered body was produced in the same manner as in Example 1 except that the sintering temperature was changed to 1350°C. Example 3 The ammonia content in solution B was set to 1.2 mol,
The content of zirconyl nitrate in the C solution was set to 1.1 mol,
A zirconia-dispersed hydroxyapatite sintered body was produced in the same manner as in Example 1 except that the sintering temperature was changed to 1400°C. Comparative Example 1 A powder mixture having a composition of 80 mol% hydroxyapatite and 20 mol% zirconium oxide,
60 at 1100℃ and 200Kg/ ^cm2 in nitrogen atmosphere
The product was hot pressed for a minute and sintered to obtain a zirconia-dispersed hydroxyapatite sintered body. The obtained sintered body was tested for mechanical properties in the same manner as in Example 1. The result is the first
Shown in the table.

〔Effect of the invention〕

As explained above, the method for producing zirconium-dispersed hydroxyapatite powder of the present invention provides the following effects. Hydroxyapatite with Ca/P = 1.67 (any Ca/P of 1.5 to 1.95 depending on the purpose)
In addition, fine particles of zirconium compound can be mixed uniformly and easily, so that the hydroxyapatite powder obtained by the present invention has a practical strength (dust-free) that can be used as artificial bone, artificial tooth root material, etc. even when sintered under pressure. (including gender) can be fully achieved. The hydroxyapatite powder obtained by the present invention only partially decomposes into α-calcium phosphate (α-TCP) even at a sintering temperature of 1400°C, and can withstand sintering at high temperatures. That is, by sintering at a higher temperature, a sintered body with higher fracture toughness can be obtained. Regardless of the amount of production, homogeneous products can be obtained continuously and stably. Other than the solution mixer, general-purpose reaction equipment can be used, and no special equipment is required. Therefore, according to the present invention, uniform and high-quality zirconium-dispersed hydroxyapatite powder can be continuously produced on an industrial scale, and a sintered body made from this hydroxyapatite powder has a significantly high It is strengthened and made highly tough, and is suitably used as dental artificial tooth roots, artificial jaw bones, orthopedic artificial bones, adsorbents in the form of spherical fine particles, and the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the method for producing hydroxyapatite of the present invention, and FIG. 2 is a schematic diagram of another embodiment of the present invention. 1: Solution mixer, 2a to 2c: Inlet, 3: Outlet.

Claims (1)

[Scope of Claims] 1. A zirconium compound, an alkaline solution, and a hydroxyapatite slurry or calcium which is a hydroxyapatite raw material are fed from the plurality of inlets into a solution mixer equipped with a plurality of inlets and one outlet. A method for producing hydroxyapatite powder in which a zirconium compound is dispersed, characterized in that a salt solution and a phosphate solution are introduced, mixed and reacted, and the resulting precipitate is continuously discharged from the outlet. 2. The manufacturing method according to claim 1, wherein the zirconium compound is zirconium oxide. 3. The zirconium oxide is suspended in an alkaline solution, and the zirconium oxide suspended alkaline solution, the calcium salt solution, and the phosphate solution are introduced into the solution mixer through separate inlets, respectively. The manufacturing method described in Section 2. 4. The manufacturing method according to claim 1, wherein the zirconium compound is zirconyl nitrate or zirconium oxychloride. 5. Claim 4, wherein the mixture of zirconyl nitrate or zirconium oxychloride and calcium salt, the phosphate solution, and the alkaline solution are introduced into the solution mixer through separate inlets, respectively.
Manufacturing method described in section. 6. The manufacturing method according to claim 1, wherein the zirconium compound is a zirconia hydrate. 7. The manufacturing method according to claim 6, wherein the slurry in which the zirconia hydrate is dispersed in water and the hydroxyapatite slurry are introduced into the solution mixer from separate inlets.