JP4190230B2 - Manufacturing method of sintered body - Google Patents

Description

【０１０８】
表１に示すように、実施例１〜１０で製造された焼結体（本発明の焼結体の製造方法により製造される焼結体）は、いずれも、相対密度が高いものであった。
【０１０９】
また、圧粉体の製造において、加圧の圧力を２〜３ｔｏｎ／ｃｍ^２とし、圧粉体の焼成において、焼成雰囲気を酸素分圧が５５０ｍｍＨｇ以上の酸素含有雰囲気、焼成温度を１０００〜１２５０℃とすることにより、得られた焼結体は、その相対密度が特に高いものとなった。
【０１１０】
これに対し、比較例１〜４で製造された焼結体は、いずれも、相対密度が低いものであった。
【０１１１】
また、寸法：縦４５ｍｍ、横２５ｍｍ、厚さ１５ｍｍの板状のテストピース（焼結体）を、前記実施例３および前記比較例３と同様の製造条件で、それぞれ、テストピースＡ（実施例３に対応）およびテストピースＢ（比較例３に対応）を作製した。
【０１１２】
なお、テストピースＡは、透明性を有する白色を呈し、テストピースＢは、透明性を有さない（濁ったような）白色を呈した。
【０１１３】
これらのテストピースＡ、Ｂに対して、それぞれ、次のような特性評価を行った。
【０１１４】
８５Ｗのハロゲンランプより光ファイバーを通して照射する光源を用意した。なお、この光源からの光の輝度および色度を、色彩色度計（ミノルタ社製、「ＣＳ−１００」）を用いて測定した結果、それぞれ、２３００００ｃｄ／ｍ^２、ＣＩＥ色度図の色度座標（０．５４３，０．４）であった。
【０１１５】
この光を、テストピースＡ、Ｂの厚さ１５ｍｍの部分に、それぞれ、照射して、透過光の輝度を前記色彩色度計により測定した。
【０１１６】
その結果、テストピースＡの輝度は、４８０ｃｄ／ｍ^２であった。これに対し、テストピースＢの輝度は、６３ｃｄ／ｍ^２であった。すなわち、テストピースＡ（本発明）がテストピースＢ（比較例）より、その透明性が高いことが確認された。
【０１１７】
また、テストピースＡは、その内部の状態が目視により確認可能であり、目視による確認の結果、クラック等の焼結欠陥の発生や異物の混入は、認められなかった。これに対し、テストピースＢは、透明性が低いため、その内部の状態を目視により確認することが困難であり、焼結欠陥が存在するか否かの判別も不可能であった。
【０１１８】
なお、前記実施例１、２、４〜１０および比較例１、２、４と同様の製造条件で、それぞれ、作製したテストピースについても、前記と同様にして特性評価を行った。その結果、各実施例１〜１０および比較例１〜４で製造した焼結体の相対密度と、各テストピースの特性評価結果とに対応関係があること、すなわち、相対密度が高くなるにつれて透明性が高くなる傾向にあることが確認された。
【０１１９】
【発明の効果】
以上述べたように、本発明によれば、高密度の焼結体が得られる。
【０１２０】
また、かかる焼結体は、その透明性が高いものとなるので、その内部における焼結欠陥の発生の有無や異物の混入等を、容易に発見することができる。
【０１２１】
また、製造条件を適宜設定することにより、得られる焼結体の相対密度および透明性をより高いものとすることができる。
【０１２２】
このような焼結体は、機械的強度にも優れるため、椎弓スペーサーや耳小骨等の人工骨、人工歯根等に好適に使用することができる。
【図面の簡単な説明】
【図１】本発明の焼結体の製造方法を示す工程図である。
【符号の説明】
１ ハイドロキシアパタイト粉体の製造
２ 圧粉体の製造
３ 圧粉体の整形
４ 圧粉体の焼成[0001]
[Technical field to which the invention belongs]
The present invention manufactures a sintered body On the way It is related.
[0002]
[Prior art]
Hydroxyapatite, a kind of calcium phosphate ceramics, is the main component of bones and teeth, has excellent biocompatibility, and is used as a biomaterial for artificial bones, artificial roots, medical or dental cements, etc. Has been.
[0003]
By the way, when using hydroxyapatite as a biomaterial such as an artificial bone or an artificial tooth root, a sintered body thereof is used. In this case, the sintered body is required to have sufficient mechanical strength. For this purpose, it is necessary to produce a sintered body having a high relative density, that is, a high-density sintered body.
[0004]
In addition, when a crack or the like is generated inside such a sintered body, the mechanical strength is lowered. Therefore, after the manufacturing, an internal inspection (presence / absence of a crack or the like) is performed. For this reason, it is preferable that the sintered compact has transparency.
[0005]
Here, the higher the density of the sintered body, the higher the transparency. From this point of view, it is important to produce a high-density sintered body.
[0006]
Conventionally, such a sintered body is manufactured by forming a hydroxyapatite powder into a desired shape and then sintering the obtained molded body.
[0007]
However, it has been difficult to obtain a sintered body having a satisfactory relative density (that is, a high-density sintered body) with the conventional manufacturing method.
[0008]
[Problems to be solved by the invention]
The object of the present invention is to produce a sintered body capable of producing a high-density sintered body without using a large-scale apparatus. method It is to provide.
[0009]
[Means for Solving the Problems]
Such purposes are as follows (1) to ( 12 This is achieved by the present invention.
[0010]
(1) 1 ton / cm of hydroxyapatite powder ² A step of pressing at the above pressure to obtain a green compact;
A step of obtaining a sintered body by firing the green compact at a temperature of 925 to 1300 ° C. in an oxygen-containing atmosphere having an oxygen partial pressure higher than the oxygen partial pressure of the atmosphere. Production method.
Thereby, a high-density sintered compact can be obtained.
[0011]
(2) The said pressurization is a manufacturing method of the sintered compact as described in said (1) performed isotropically.
Thereby, a higher density sintered body can be obtained.
[0012]
(3) The said isotropic pressurization is a manufacturing method of the sintered compact as described in said (2) performed by hydrostatic pressure pressurization.
Thereby, a higher density sintered body can be obtained.
[0013]
(4) The method for producing a sintered body according to (3), wherein the hydrostatic pressure is performed at a temperature of 5 to 50 ° C.
[0014]
Such a method for producing a green compact can be performed with a simple apparatus, and is excellent in practicality as a production process for industrial products.
[0015]
(5) The method for manufacturing a sintered body according to any one of (1) to (4), wherein an oxygen partial pressure of the oxygen-containing atmosphere is 380 mmHg or more.
Thereby, a higher density sintered body can be obtained.
[0016]
(6) The hydroxyapatite powder is synthesized by a wet synthesis method using at least one of a calcium source and a phosphoric acid source as a solution, and is produced using a slurry obtained in the synthesis. The manufacturing method of the sintered compact in any one of 1) thru | or (5).
[0017]
Thus, it is possible to synthesize hydroxyapatite easily and efficiently without requiring expensive production equipment.
[0018]
(7) The sintered body according to (6), wherein the calcium source has calcium hydroxide or calcium oxide as a main component, and the phosphoric acid source has phosphoric acid as a main component. Production method.
[0019]
Thereby, hydroxyapatite can be synthesized more efficiently and inexpensively.
[0020]
(8) The said hydroxyapatite powder is a manufacturing method of the sintered compact as described in said (7) which is manufactured using the said slurry whose content of tricalcium phosphate is 0.1 wt% or less.
Thereby, a higher density sintered body can be obtained.
[0021]
(9) The said hydroxyapatite powder is a manufacturing method of the sintered compact as described in said (7) or (8) which is manufactured using the said slurry which satisfies the following conditions A.
Condition A: A part of the slurry is taken out and the molding pressure is 2 ton / cm. ² After forming a sample molded body having a detection surface by compression molding, a sample detection surface (surface roughness Ra = 10 μm) obtained by firing the sample molded body in the atmosphere at 1200 ° C. for 2 hours. When the substance present in is analyzed by X-ray diffraction, the peak intensity derived from hydroxyapatite is the largest among the obtained peaks, and no peak derived from tricalcium phosphate is observed.
[0022]
By using such a slurry, a particularly high-density sintered body can be obtained.
[0023]
(10) The hydroxyapatite powder according to any one of (7) to (9), wherein the hydroxyapatite powder is manufactured using the slurry having a calcium hydroxide or calcium oxide content of 0 to 3 wt%. A method for producing a sintered body.
Thereby, a higher density sintered body can be obtained.
[0024]
(11) The method for producing a sintered body according to any one of (7) to (10), wherein the hydroxyapatite powder is produced using the slurry that satisfies the following condition B.
Condition B: A part of the slurry is taken out and the molding pressure is 2 ton / cm. ² After forming a sample molded body having a detection surface by compression molding, a sample detection surface (surface roughness Ra = 10 μm) obtained by firing the sample molded body in the atmosphere at 1200 ° C. for 2 hours. When X-ray diffraction analyzes the substance present in the sample, the relationship of Y / X <1/10 is satisfied, where X is the peak intensity derived from hydroxyapatite and Y is the peak intensity derived from calcium oxide. To do.
[0025]
By using such a slurry, a particularly high-density sintered body can be obtained.
[0026]
(12) A sintered body is prepared so as to have a plate shape with a thickness of 15 mm, and a luminance of 230,000 cd / m is applied to the sintered body. ² And when the light of the chromaticity coordinates (0.543, 0.4) of the CIE chromaticity diagram is irradiated, the luminance of the transmitted light is 150 cd / m. ² The method for producing a sintered body according to any one of (1) to (11) above.
[0027]
A sintered body (test piece) having such characteristics can be determined to have high transparency, and a sintered body manufactured under the same conditions can also be determined to have high transparency. . A sintered body having high transparency can easily find out whether or not a sintering defect such as a crack is generated in the inside of the sintered body and whether or not a foreign substance is mixed in the inside of the sintered body.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the production of the sintered body of the present invention Way of Preferred embodiments will be described in detail.
[0031]
FIG. 1 is a process diagram showing a method for producing a sintered body of the present invention.
The sintered body manufacturing method shown in FIG. 1 includes a hydroxyapatite powder manufacturing process 1, a green compact manufacturing process 2, a green compact shaping process 3, and a green compact firing process 4. is doing. Hereinafter, each process will be described sequentially.
[0032]
[1] Production of hydroxyapatite powder
First, a calcium source and a phosphate source are reacted to synthesize hydroxyapatite (HAp). In addition, the hydroxyapatite in this specification points out that whose Ca / P molar ratio is 1.60 to 1.70.
[0033]
Any method such as a wet synthesis method, a dry synthesis method, or a hydrothermal synthesis method may be used for the synthesis of the hydroxyapatite, but a wet synthesis method using at least one of a calcium source and a phosphate source as a solution is used. Is preferred. Thus, it is possible to synthesize hydroxyapatite easily and efficiently without requiring expensive production equipment.
[0034]
When the wet synthesis method is used, as the calcium source, for example, calcium hydroxide, calcium oxide, calcium nitrate or the like can be used. On the other hand, phosphoric acid, ammonium phosphate, or the like can be used as the phosphoric acid source. Among these, in particular, those having calcium hydroxide or calcium oxide as a main component as a calcium source and those having phosphoric acid as a main component as a phosphoric acid source are preferable. By using such calcium source and phosphate source, hydroxyapatite can be synthesized more efficiently and inexpensively.
[0035]
Hereinafter, a case where a calcium source having calcium hydroxide or calcium oxide as a main component and a phosphoric acid source having phosphoric acid as a main component are used will be described.
[0036]
In this case, hydroxyapatite (HAp) is, for example, calcium hydroxide (Ca (OH)) in a container. ₂ ) Or calcium oxide (CaO) suspension in phosphoric acid (H _Three PO _Four ) It is synthesized by dropping the solution and mixing.
[0037]
This reaction is represented by the following formula (I) or (II).
10Ca (OH) ₂ + 6H _Three PO _Four → 2Ca _Five (PO _Four ) _Three (OH) + 18H ₂ O (I)
10CaO + 10H ₂ O + 6H _Three PO _Four → 2Ca _Five (PO _Four ) _Three (OH) + 18H ₂ O (II)
Here, if the progress of the synthesis is insufficient, the unreacted product (Ca (OH)) is contained in a slurry-like mixture (hereinafter simply referred to as “slurry”). ₂ And CaO) will be present as impurities.
[0038]
When the reaction is further continued, tricalcium phosphate (TCP) is produced as a secondary reaction product by the reaction represented by the following formula (III).
[0039]
3Ca _Five (PO _Four ) _Three (OH) + H _Three PO _Four → 5Ca _Three (PO _Four ) ₂ + 3H ₂ O (III)
As this reaction proceeds, tricalcium phosphate, which is a secondary reaction product, will be present as impurities in the slurry.
[0040]
By using a slurry containing hydroxyapatite synthesized in this way, a hydroxyapatite powder is produced, but the present inventor makes almost no impurities as described above in the slurry, It has been found that the relative density of the obtained sintered body can be increased, that is, a high-density sintered body can be obtained.
[0041]
Hereinafter, tricalcium phosphate and unreacted substances (Ca (OH)) in the slurry. ₂ , CaO) content (concentration) suitable ranges will be described respectively.
[0042]
[Tricalcium phosphate]
The content (concentration) of tricalcium phosphate in the slurry is not particularly limited, but is preferably 0.1 wt% or less, more preferably not present. Thus, a higher density sintered body can be obtained by using a slurry having a low content of tricalcium phosphate.
[0043]
Furthermore, a slurry that satisfies the following condition A is optimal.
[0044]
Condition A: A part of the slurry is taken out and the molding pressure is 2 ton / cm. ² After forming a sample molded body having a detection surface by compression molding, a sample detection surface (surface roughness Ra = 10 μm) obtained by firing the sample molded body in the atmosphere at 1200 ° C. for 2 hours. The substance present in the sample is analyzed by X-ray diffraction. At this time, the peak intensity derived from hydroxyapatite is the highest among the obtained peaks, and no peak derived from tricalcium phosphate is observed.
[0045]
In such an analysis method, during the firing, the particle growth of hydroxyapatite precedes due to the difference in sintering rate between hydroxyapatite and impurities, and as a result, the impurities are pushed out from the interstices, and the sample surface (particularly the detection surface) The presence of impurities can be confirmed by analyzing the detection surface by X-ray diffraction using the precipitation in (1). According to this analysis method, the presence of impurities in the slurry can be confirmed with high accuracy.
[0046]
And if a slurry satisfies the said conditions A, this will be understood that even if it does not contain tricalcium phosphate or contains tricalcium phosphate, it is a very small amount. For this reason, a particularly high-density sintered body can be obtained by using such a slurry.
[0047]
[Unreacted material]
The content (concentration) of the unreacted substance in the slurry is not particularly limited, but is preferably about 0 to 3 wt%, and more preferably about 0.025 to 1 wt%. When a relatively small amount of unreacted material is present in the slurry, calcium oxide (note that unreacted calcium hydroxide changes to calcium oxide by firing) increases the relative density of the resulting sintered body. Due to the tendency, a higher-density sintered body can be obtained. If the content of the unreacted material in the slurry exceeds the upper limit, it may be difficult to obtain a high-density sintered body depending on the firing conditions of the green compact described later.
[0048]
Furthermore, a slurry that satisfies the following condition B is optimal.
[0049]
Condition B: A part of the slurry is taken out and the molding pressure is 2 ton / cm. ² After forming a sample molded body having a detection surface by compression molding, a sample detection surface (surface roughness Ra = 10 μm) obtained by firing the sample molded body in the atmosphere at 1200 ° C. for 2 hours. The substance present in the sample is analyzed by X-ray diffraction. At this time, when the intensity of the peak derived from hydroxyapatite is X and the intensity of the peak derived from calcium oxide is Y, a relationship of Y / X <1/10 (particularly, a relationship of Y / X <1/100). ) Is satisfied.
[0050]
As described above, according to the analysis method, it is possible to confirm the presence of impurities in the slurry with high accuracy. As a result, if the slurry satisfies the condition B, this contains unreacted substances. It can be seen that the amount is very small. For this reason, a particularly high-density sintered body can be obtained by using such a slurry.
[0051]
Note that the slurry may be one in which either the content of tricalcium phosphate or the content of unreacted material is in the above range, but those in which both are in the above range are preferred. Thereby, an extremely high density sintered body can be obtained.
[0052]
Next, a hydroxyapatite powder (hereinafter simply referred to as “powder”) is produced by subjecting the slurry thus obtained to, for example, spray drying.
[0053]
The average particle size of the powder is not particularly limited, but is preferably about 1 to 30 μm, and more preferably about 8 to 25 μm. By using a powder having such an average particle diameter, a higher density sintered body can be obtained.
[0054]
In addition, in order to obtain a more compact green compact, the obtained powder is heat treated under, for example, a processing condition of about 500 to 800 ° C. for about 2 to 6 hours, and then pulverized with, for example, a jet mill or a turbo mill, The average particle size may be about 6 to 20 μm (average particle size of about 50 to 80% before pulverization).
[0055]
[2] Production of green compact
Next, pressure is applied to the obtained powder (or a powder that has been compacted in advance into a desired shape) to be consolidated.
[0056]
The method of pressurization may be any one of a method of isotropic pressurization, a method of pressurizing only in one direction (uniaxial direction) such as a uniaxial press, etc., but isotropically pressurizes. The method, particularly hydrostatic pressure is preferred. Thereby, the density of the green compact after pressurization can be made uniform, and as a result, a higher density sintered body can be obtained.
[0057]
As hydrostatic pressure pressurization, for example, a CIP (Cold Isostatic press) method in which pressurization is performed at a temperature of about 5 to 50 ° C. (preferably about 10 to 30 ° C.) and a pressurization under heating (for example, 65 ° C. or more). HIP (Hot Isostatic Press) method and Hot press method, but it is preferable to use the CIP method. The CIP method can be performed with a simple apparatus, has an advantage that a heat resistance is not required for a coating described later, and is excellent in practicality as a manufacturing process for industrial products.
[0058]
As a specific method of hydrostatic pressure pressurization, the surface of the powder is covered with a liquid-blocking coating, and this is loaded into a hydrostatic pressurizer and subjected to hydrostatic pressurization. In the case of the CIP method, as the coating, for example, a resin material such as polyvinyl chloride, polyethylene, or polypropylene, or a rubber material such as natural rubber or isoprene rubber can be used. This coating can be formed, for example, by dipping or vacuum packing.
[0059]
The pressure for pressurization (pressurization pressure) is not particularly limited, but is 1 ton / cm. ² Preferably, it is 1 to 3 ton / cm. ² More preferably, it is about 2-3 ton / cm ² More preferably, it is about. If this pressure is too low, the effect of sufficient pressurization (particularly uniform density) may not be expected, and even if the pressure is made higher than the above upper limit value, no improvement in the effect is observed. Large equipment is required, and the equipment becomes expensive.
[0060]
The green compact after pressurization thus obtained has a high density and the density becomes uniform. When sintered by firing, which will be described later, the shrinkage rate decreases and shrinks uniformly, so the final obtained sintered body has high dimensional accuracy, and the sintered body has a uniform density, cracks and defects. As a result, it becomes difficult to break (excellent in mechanical strength).
In addition, after pressurization, the coating on the surface is removed by a predetermined method.
[0061]
[3] Shaping of green compact
Next, the shape or size of the obtained green compact is adjusted as necessary.
[0062]
The shaping of the green compact is performed, for example, by subjecting the green compact to predetermined machining. Examples of the machining include cutting, grinding, polishing, and the like, and one or more of these can be combined.
[0063]
Since the green compact itself has a much lower hardness than the finally obtained sintered body, shaping of the green compact by machining or the like can be performed easily. It can also be used, and the machining speed is high.
[0064]
[4] Firing of green compact
The green compact obtained as described above is sintered (fired) in an oxygen-containing atmosphere having an oxygen partial pressure higher than the oxygen partial pressure in the atmosphere, for example, in a firing furnace to obtain a sintered body.
[0065]
As a result of intensive studies, the present inventor can obtain a sintered body having a particularly high density by firing the green compact in an oxygen-containing atmosphere having an oxygen partial pressure higher than the atmospheric oxygen partial pressure. I found.
[0066]
A typical example of such an oxygen-containing atmosphere (firing atmosphere) is a pure oxygen atmosphere. As the oxygen-containing atmosphere, a mixed gas of oxygen and another gas (especially, a mixed gas mainly containing oxygen) is used. You can also.
[0067]
In addition, when the green compact is fired under a pressure higher than atmospheric pressure (for example, 2 to 10 atm), the oxygen partial pressure becomes higher than the oxygen partial pressure in the atmosphere. It can also be used.
[0068]
Note that when firing the green compact under atmospheric pressure (1 atm), there is no need to use a firing furnace having high airtightness. In other words, it is preferable in that a firing furnace having a simple configuration can be used. Thereby, reduction of the manufacturing cost of a sintered compact can be aimed at.
[0069]
The oxygen partial pressure of such an oxygen-containing atmosphere (in the case of a pure oxygen atmosphere, the pressure in the firing furnace) is preferably 380 mmHg or more, and more preferably 550 mmHg or more. Thereby, the relative density of the obtained sintered compact can be made higher.
[0070]
Note that in order to increase the oxygen partial pressure of the oxygen-containing atmosphere at atmospheric pressure, the volume of oxygen in the oxygen-containing atmosphere (firing atmosphere) may be increased (concentration increased).
[0071]
In addition, the present inventor can make the firing temperature (firing temperature) relatively low by firing the green compact in such an oxygen-containing atmosphere with a high oxygen partial pressure. The inventors have also found that the green compact can be sintered while suppressing the particle growth of hydroxyapatite, and as a result, a sintered body with higher density can be obtained.
[0072]
In addition, by firing the green compact at such a relatively low temperature, it is possible to shorten the firing time, reduce the energy required for firing, reduce the cost of the heating element used in the firing furnace, and the like. There are also advantages.
[0073]
The temperature (firing temperature) in this firing is 925 to 1300 ° C, preferably about 1000 to 1250 ° C. Note that if the firing temperature is too low, the green compact may not be sintered efficiently.
[0074]
The holding time (baking time) of the baking temperature is preferably about 30 minutes to 8 hours, and more preferably about 2 to 4 hours.
Through the above process, Sintered body Is obtained.
[0075]
Sintered body manufactured by the method for manufacturing a sintered body of the present invention Has a high density and an extremely high mechanical strength. For this reason, This sintered body Can be suitably used as biomaterials such as artificial bones such as vertebral arch spacers and ossicles, and artificial tooth roots.
[0076]
Moreover, it is preferable that the sintered compact manufactured by the manufacturing method of the sintered compact of this invention has the following characteristics.
[0077]
That is, a test piece (sintered body) was prepared so as to have a plate shape with a thickness of 15 mm, and a luminance of 230000 cd / m ² And when the light of the chromaticity coordinates (0.543, 0.4) of the CIE chromaticity diagram is irradiated, the luminance of the transmitted light is 150 cd / m. ² Above (especially 200 cd / m ² The above characteristics are obtained.
[0078]
Here, the reason for using the test piece will be described. The actual sintered body is appropriately set in shape, size, etc. according to its intended use. For this reason, even if the luminance of transmitted light is measured under the same conditions, there are cases where evaluation cannot be performed uniformly. Therefore, a test piece is prepared according to the method for manufacturing a sintered body described above, and if the test piece has the above characteristics, an actual sintered body manufactured under the same conditions as this is also a test piece. This is because it can be estimated that a characteristic corresponding to the confirmed characteristic is obtained.
[0079]
And it can be judged that the test piece which has the said characteristic is a thing with the high transparency, and the sintered compact manufactured on the same conditions can also be judged to be a thing with high transparency.
[0080]
A sintered body having high transparency can easily find out whether or not a sintering defect such as a crack is generated in the inside of the sintered body and whether or not a foreign substance is mixed in the inside of the sintered body.
[0081]
As described above, the sintered body of the present invention Production method However, the present invention is not limited to these.
[0082]
For example, in the present invention, for any purpose, a pre-step of step [1], an intermediate step existing between steps [1] to [4], or a post-step of step [4] may be provided. .
[0083]
【Example】
Next, specific examples of the method for producing a sintered body of the present invention will be described.
[0084]
[Production of sintered body]
The sintered bodies of Examples 1 to 10 and Comparative Examples 1 to 4 were manufactured as follows.
[0085]
(Example 1)
<1> First, 140 g of calcium hydroxide is dispersed in 6 liters of pure water, and a phosphoric acid aqueous solution having a phosphoric acid concentration of 2 wt% is dropped therein, and the mixture is sufficiently stirred and mixed to synthesize hydroxyapatite. A slurry containing was obtained.
[0086]
Next, the slurry was spray-dried using a spray dryer to obtain a hydroxyapatite powder having an average particle size of 20 μm.
[0087]
At this time, a part of the slurry is taken out and the molding pressure is 2 ton / cm. ² After forming a sample molded body having a detection surface by compression molding, a sample detection surface (surface roughness Ra = 10 μm) obtained by firing the sample molded body in the atmosphere at 1200 ° C. for 2 hours. The substances present in were analyzed by X-ray diffraction. The sample dimensions were 15 mm in diameter and 8 mm in height.
[0088]
As a result, the peak derived from tricalcium phosphate (TCP) was not confirmed, and the intensity of the peak derived from calcium oxide (CaO) was 1/250 of the intensity of the peak derived from hydroxyapatite (HAp). .
[0089]
Furthermore, the obtained hydroxyapatite powder was heat-treated at 600 ° C. for 4 hours, and then pulverized by a jet mill. Thereby, a hydroxyapatite powder having an average particle size of 16 μm was obtained.
[0090]
<2> Next, this hydroxyapatite powder is hardened into a cylindrical shape with a compression molding machine, and then packed in a vinyl bag and vacuum-packed, and hydrostatic pressure is applied at room temperature (24 ° C.). 1 ton / cm ² A cylindrical green compact having a diameter of 21 mm and a height of 52 mm was obtained.
[0091]
<3> Next, the green compact was cut (machined) with a diamond cutter to form a cylinder having a diameter of 20 mm and a height of 50 mm.
[0092]
<4> Next, this green compact was fired in a firing furnace to obtain a sintered body. The firing conditions were 1050 ° C. × 2 hours in a pure oxygen atmosphere (firing atmosphere). The pressure in the firing furnace was 760 mmHg (1 atm).
[0093]
(Example 2)
In the step <2>, the hydrostatic pressure is 1.5 ton / cm. ² A sintered body was manufactured in the same manner as in Example 1 except that.
[0094]
(Example 3)
In the step <2>, the hydrostatic pressure is set at 2.0 ton / cm. ² A sintered body was manufactured in the same manner as in Example 1 except that.
[0095]
Example 4
A sintered body was manufactured in the same manner as in Example 3 except that in the step <4>, the firing condition was 925 ° C. × 2 hours in a pure oxygen atmosphere.
[0096]
(Example 5)
A sintered body was produced in the same manner as in Example 3 except that in the step <4>, the firing conditions were 950 ° C. × 2 hours in a pure oxygen atmosphere.
[0097]
(Example 6)
A sintered body was produced in the same manner as in Example 3 except that in the step <4>, the firing condition was 1000 ° C. × 2 hours in a pure oxygen atmosphere.
[0098]
(Example 7)
A sintered body was produced in the same manner as in Example 3 except that in the step <4>, the firing condition was 1250 ° C. × 2 hours in a pure oxygen atmosphere.
[0099]
(Example 8)
A sintered body was produced in the same manner as in Example 3 except that in the step <4>, the firing conditions were 1050 ° C. × 2 hours in a mixed gas atmosphere of oxygen and argon gas. The oxygen partial pressure was 190 mmHg.
[0100]
Example 9
A sintered body was produced in the same manner as in Example 3 except that in the step <4>, the firing conditions were 1050 ° C. × 2 hours in a mixed gas atmosphere of oxygen and argon gas. The oxygen partial pressure was 380 mmHg.
[0101]
(Example 10)
A sintered body was produced in the same manner as in Example 3 except that in the step <4>, the firing conditions were 1050 ° C. × 2 hours in a mixed gas atmosphere of oxygen and argon gas. The oxygen partial pressure was 570 mmHg.
[0102]
(Comparative Example 1)
In the step <2>, the hydrostatic pressure is 0.5 ton / cm. ² A sintered body was manufactured in the same manner as in Example 1 except that.
[0103]
(Comparative Example 2)
A sintered body was produced in the same manner as in Example 1 except that in the step <4>, the firing conditions were 1050 ° C. × 2 hours in a pure argon gas atmosphere.
[0104]
(Comparative Example 3)
A sintered body was produced in the same manner as in Example 3 except that in the step <4>, the firing condition was 1050 ° C. × 2 hours in the atmosphere of 1 atm.
[0105]
(Comparative Example 4)
A sintered body was produced in the same manner as in Example 3 except that in the step <4>, the firing conditions were 900 ° C. × 2 hours in a pure oxygen atmosphere.
[0106]
[Evaluation]
Relative to the sintered bodies produced in Examples 1 to 10 and Comparative Examples 1 to 4 in consideration of the specific gravity based on the volume value obtained from the outer dimensions and the weight value, respectively. The density was determined.
The results of this evaluation are shown in Table 1 together with the production conditions for the sintered body.
[0107]
[Table 1]

[0108]
As shown in Table 1, the sintered bodies manufactured in Examples 1 to 10 ( Sintered body manufactured by the method for manufacturing a sintered body of the present invention ) All had a high relative density.
[0109]
Further, in the production of the green compact, the pressure is set to 2 to 3 ton / cm. ² When the green compact is fired, the sintered body obtained by setting the firing atmosphere to an oxygen-containing atmosphere having an oxygen partial pressure of 550 mmHg or higher and a firing temperature of 1000 to 1250 ° C. has a particularly high relative density. It became.
[0110]
On the other hand, all of the sintered bodies produced in Comparative Examples 1 to 4 had a low relative density.
[0111]
In addition, a plate-shaped test piece (sintered body) having dimensions of 45 mm in length, 25 mm in width, and 15 mm in thickness was tested under the same manufacturing conditions as in Example 3 and Comparative Example 3, respectively. 3) and test piece B (corresponding to Comparative Example 3).
[0112]
Note that the test piece A exhibited a white color having transparency, and the test piece B exhibited a white color having no transparency (such as turbidity).
[0113]
The following characteristic evaluations were performed on these test pieces A and B, respectively.
[0114]
A light source was prepared for irradiation through an optical fiber from an 85W halogen lamp. In addition, as a result of measuring the brightness | luminance and chromaticity of the light from this light source using the color chromaticity meter (the Minolta company make, "CS-100"), it is 230000 cd / m, respectively. ² The chromaticity coordinates (0.543, 0.4) of the CIE chromaticity diagram.
[0115]
This light was irradiated to the 15 mm thick portions of the test pieces A and B, respectively, and the luminance of the transmitted light was measured by the color and colorimeter.
[0116]
As a result, the brightness of the test piece A is 480 cd / m. ² Met. On the other hand, the brightness of the test piece B is 63 cd / m. ² Met. That is, it was confirmed that the test piece A (the present invention) has higher transparency than the test piece B (comparative example).
[0117]
Moreover, the test piece A was able to visually confirm the internal state, and as a result of visual confirmation, the occurrence of sintering defects such as cracks and the inclusion of foreign matter were not observed. On the other hand, since the test piece B has low transparency, it is difficult to visually check the internal state of the test piece B, and it is impossible to determine whether or not there is a sintering defect.
[0118]
In addition, under the same manufacturing conditions as in Examples 1, 2, 4 to 10 and Comparative Examples 1, 2, and 4, the test pieces that were produced were evaluated for characteristics in the same manner as described above. As a result, there is a corresponding relationship between the relative density of the sintered bodies produced in Examples 1 to 10 and Comparative Examples 1 to 4 and the characteristic evaluation results of each test piece, that is, the transparency increases as the relative density increases. It was confirmed that there is a tendency to increase the nature.
[0119]
【The invention's effect】
As described above, according to the present invention, a high-density sintered body can be obtained.
[0120]
In addition, since the sintered body has high transparency, it is possible to easily find out whether or not a sintering defect is generated in the inside of the sintered body and mixing of foreign matters.
[0121]
Moreover, the relative density and transparency of the obtained sintered body can be made higher by appropriately setting the production conditions.
[0122]
Since such a sintered body is excellent in mechanical strength, it can be suitably used for artificial bones such as vertebral arch spacers and ossicles, artificial tooth roots, and the like.
[Brief description of the drawings]
FIG. 1 is a process diagram illustrating a method for producing a sintered body according to the present invention.
[Explanation of symbols]
1. Production of hydroxyapatite powder
2 Production of green compact
3 Molding of green compact
4 Firing of green compact

Claims (12)

Pressing the hydroxyapatite powder at a pressure of 1 ton / cm ² or more to obtain a green compact;
A step of obtaining a sintered body by firing the green compact at a temperature of 925 to 1300 ° C. in an oxygen-containing atmosphere having an oxygen partial pressure higher than the oxygen partial pressure of the atmosphere. Production method.   The method for producing a sintered body according to claim 1, wherein the pressing is performed isotropically.   The method for producing a sintered body according to claim 2, wherein the isotropic pressurization is performed by hydrostatic pressurization.   The method for producing a sintered body according to claim 3, wherein the hydrostatic pressure is performed at a temperature of 5 to 50 ° C. 5.   The method for producing a sintered body according to any one of claims 1 to 4, wherein an oxygen partial pressure of the oxygen-containing atmosphere is 380 mmHg or more.   6. The hydroxyapatite powder is synthesized by a wet synthesis method using at least one of a calcium source and a phosphoric acid source as a solution, and is produced using a slurry obtained in the synthesis. The manufacturing method of the sintered compact in any one of.   The method for producing a sintered body according to claim 6, wherein the calcium source includes calcium hydroxide or calcium oxide as a main component, and the phosphoric acid source includes phosphoric acid as a main component.   The method for producing a sintered body according to claim 7, wherein the hydroxyapatite powder is produced using the slurry having a tricalcium phosphate content of 0.1 wt% or less. The method for producing a sintered body according to claim 7 or 8, wherein the hydroxyapatite powder is produced using the slurry that satisfies the following condition A.
Condition A: A part of the slurry is taken out and compression molded at a molding pressure of ² ton / cm ² to form a sample molded body having a detection surface, and then the sample molded body is fired in the atmosphere at 1200 ° C. for 2 hours. When the substance present on the detection surface (surface roughness Ra = 10 μm) of the obtained sample is analyzed by X-ray diffraction, the peak intensity derived from hydroxyapatite is the largest among the obtained peaks, and No peak derived from tricalcium phosphate is observed.   The method for producing a sintered body according to any one of claims 7 to 9, wherein the hydroxyapatite powder is produced using the slurry having a calcium hydroxide or calcium oxide content of 0 to 3 wt%. . The method for manufacturing a sintered body according to any one of claims 7 to 10, wherein the hydroxyapatite powder is manufactured using the slurry that satisfies the following condition B.
Condition B: A part of the slurry is taken out and compression molded at a molding pressure of ² ton / cm ² to form a sample molded body having a detection surface, and then the sample molded body is fired in the atmosphere at 1200 ° C. for 2 hours. When the substance present on the detection surface (surface roughness Ra = 10 μm) of the sample obtained in this way is analyzed by X-ray diffraction, the intensity of the peak derived from hydroxyapatite is X, and the intensity of the peak derived from calcium oxide When Y is Y, the relationship Y / X <1/10 is satisfied. A sintered body is produced so as to have a plate shape with a thickness of 15 mm, and the sintered body is irradiated with light having a luminance of 230,000 cd / m ² and chromaticity coordinates (0.543, 0.4) in the CIE chromaticity diagram. The method for producing a sintered body according to any one of claims 1 to 11, wherein the brightness of transmitted light is 150 cd / m ² or more.

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