JP2003020284A - Method for manufacturing sintered compact and sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple method for manufacturing a sintered compact and the sintered compact which is manufactured by such manufacturing method and is usable for, for example, artificial bones, dental roots, or the like. SOLUTION: This method for manufacturing the sintered compact has a process step of putting a slurry 1 contg. hydroxy-apatite which is a synthesize material obtained by mixing, for example, calcium hydroxide (first raw material) and an aqueous phosphoric acid (second raw material) solution and reacting these raw materials into a mold 10 and applying a centrifugal force to the slurry, thereby obtaining a molding 2 and a process step of obtaining the sintered compact 3 by firing the molding 2. The number of revolutions (number of centrifugal revolutions) of the mold 19 is continuously or stepwise changed, by which the density of the molding 2 can be changed in the direction where the centrifugal force acts.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a sintered body and a sintered body.

[0002]

2. Description of the Related Art For example, hydroxyapatite, which is a type of calcium phosphate compound (ceramics material), is a main component of bones and teeth and has excellent biocompatibility. It is used as a biomaterial such as a dental cement or dental cement.

Such hydroxyapatite is molded into a molded body having a desired shape and then fired to obtain a sintered body, and the sintered body is clinically used as an artificial bone, an artificial tooth root or the like. It is used.

Conventionally, such a sintered body (hydroxyapatite sintered body) is manufactured through the following steps. <1> Hydroxyapatite is synthesized by, for example, a wet synthesis method to obtain a mixture containing hydroxyapatite. <2> Next, a spherical powder of hydroxyapatite is granulated from this mixture by a spray heat drying method, and this is calcinated and then pulverized to obtain a hydroxyapatite powder. <3> Next, this hydroxyapatite powder is filled in a molding die, and a molded body is obtained by, for example, compression molding (compacting powder molding). <4> Next, the molded body is machined, for example, to obtain a processed body having a desired shape. <5> Next, a sintered body is obtained by subjecting this processed body to main firing.

In such a method for producing a sintered body, the number of steps is large, which requires time and labor.

When the sintered body is used as an artificial bone, an artificial tooth root or the like, the sintered body is required to have both sufficient mechanical strength and osteoconductivity. Therefore, such a sintered body is configured to have a dense portion for ensuring mechanical strength and a relatively porous portion for ensuring osteoconductivity.

Conventionally, in order to obtain such a sintered body, a dense portion and a relatively porous portion are separately produced according to the above-described production method, and these portions are produced. For example, a method of joining with an adhesive or the like is used.

[0008] However, such a method is extremely complicated and requires time and labor.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a simple method for producing a sintered body and a sintered body produced by such a production method, which can be used, for example, in an artificial bone or an artificial tooth root. To do.

[0010]

The above objects are achieved by the present invention described in (1) to (17) below.

(1) A first raw material and a second raw material are mixed, and a slurry containing a compound obtained by reacting them is put in a molding die and a centrifugal force is applied to obtain a molded body. A method for producing a sintered body, comprising: a step; and a step of firing the molded body to obtain a sintered body. Thereby, the sintered body can be manufactured by a simple method.

(2) The method for producing a sintered body according to (1), wherein at least one of the first raw material and the second raw material is used as a solution. Thereby, a synthetic product can be obtained more easily and efficiently.

(3) The sintered body according to the above (1) or (2), wherein the centrifugal rotation speed is continuously or stepwise changed to change the density of the compact in the direction in which the centrifugal force acts. Manufacturing method. Thereby, the density of the molded body (sintered body) can be changed.

(4) A step of obtaining a molded article having a portion whose density changes in the direction in which the centrifugal force acts by putting a slurry containing the compound into a molding die and applying a centrifugal force, and the molded article And a step of obtaining a sintered body by firing.

With this, a sintered body having a portion where the density changes can be manufactured by a simple method.

(5) The method for producing a sintered body according to the above (4), wherein the centrifugal rotation speed is changed continuously or stepwise to change the density of the molded body.

With this, the density of the molded body (sintered body) can be changed more easily.

(6) The above-mentioned compound is the first raw material and the second raw material.
The method for producing a sintered body according to the above (4) or (5), which is obtained by mixing the raw material of 1. and reacting them. Thereby, a synthetic product can be obtained more easily and efficiently.

(7) The method for producing a sintered body according to (6), wherein the slurry is obtained when the first raw material and the second raw material are mixed.

As a result, the number of steps can be reduced and the sintered body can be manufactured in a shorter time.

(8) The method for producing a sintered body according to (6) or (7), wherein at least one of the first raw material and the second raw material is used as a solution. Thereby, a synthetic product can be obtained more easily and efficiently.

(9) The method for producing a sintered body according to any one of the above (1) to (8), wherein an organic substance for adjusting the density of the compact is added to the slurry. Thereby, the density of the molded body (sintered body) can be adjusted appropriately.

(10) A is the specific gravity of the organic substance,
When the specific gravity of the compound is B, A / B is 0.2 to
The method for producing a sintered body according to the above (9), which is 0.85.

As a result, the density of the molded body (sintered body) can be changed more reliably.

(11) The method for producing a sintered body according to any one of the above (1) to (10), wherein a release agent is applied to the inner surface of the molding die.

With this, when the molded product is taken out from the molding die, it is possible to suitably prevent the molded product from losing its shape and being damaged.

(12) The firing temperature is 1000
The method for producing a sintered body according to any one of (1) to (11) above, wherein the temperature is not lower than 0 ° C. and is lower than the temperature at which the compound thermally decomposes.

This makes it possible to make the density of the sintered body suitable and to prevent the quality of the sintered body from deteriorating.

(13) The sintered body has a relative density of 70.
% Or more, The manufacturing method of the sintered compact in any one of said (1) thru | or (12).

As a result, the sintered body as a whole can exhibit sufficient mechanical strength.

(14) The method for producing a sintered body according to any one of (1) to (13), wherein the composite is a ceramic material.

(15) The method for producing a sintered body according to the above (14), wherein the ceramic material is a calcium phosphate compound.

(16) The method for producing a sintered body according to the above (15), wherein the calcium phosphate compound is hydroxyapatite.

The present invention is suitable for producing a ceramic material, in particular, a sintered body of hydroxyapatite which is one of calcium phosphate compounds.

(17) A sintered body produced by the method for producing a sintered body according to any one of the above (1) to (16). The sintered body of the present invention can be suitably used as an artificial bone, an artificial tooth root or the like.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a sintered body and the sintered body of the present invention will be described in detail below.

FIG. 1 is a diagram for explaining the method for producing a sintered body of the present invention, and FIG. 2 is a diagram showing a change pattern of centrifugal rotation speed.

First, before describing the method for producing a sintered body of the present invention, an example of the sintered body 3 of the present invention produced by such a production method will be described.

In the present embodiment, the sintered body 3 will be described as having a shell shape as a whole (see FIG. 1B), but the shape of the sintered body 3 is not limited to this. Instead, it can be set to a desired shape according to the purpose.

The compound in the present invention may be either an organic material or an inorganic material, but an inorganic material is preferable, and a ceramic material is particularly preferable because it is a substance having sinterability.

Examples of the ceramic material include ceramics such as alumina, silica, titania, zirconia, yttria, and calcium phosphate compounds, silicon nitride,
Nitride ceramics such as aluminum nitride, titanium nitride and boron nitride, carbide ceramics such as graphite and tungsten carbide, and others such as barium titanate, strontium titanate, PZT, PLZT, PL
A ferroelectric material such as LZT can be used.

Here, the calcium phosphate compound is used, for example, in biomaterials, and specific examples thereof include apatites such as hydroxyapatite, fluoroapatite, carbonate apatite, dicalcium phosphate, tricalcium phosphate, and the like. Examples include tetracalcium phosphate, octacalcium phosphate, and the like. Of these, hydroxyapatite has a high biocompatibility and is used as a biomaterial, in particular, an artificial bone or an artificial tooth root, a medical or dental filler (cement), or the like.

In this embodiment, hydroxyapatite will be representatively described as a synthetic product. However, it goes without saying that the present invention is not limited to this.

The sintered body 3 preferably has a portion whose density changes in the direction in which centrifugal force acts in the step [2] described later. In the present embodiment, the sintered body 3 includes a dense portion 31 (lower side in FIG. 1B), and a rough portion 32 that is coarser than the dense portion 31 (upper side in FIG. 1B). have. This allows the sintered body 3 to have both sufficient mechanical strength and osteoconductivity.

The interface between the dense portion 31 and the rough portion 32 may or may not be clear. That is, the density (porosity) of the sintered body 3 may be either continuously changing or stepwise changing.

The relative density (average) of the sintered body 3 is preferably 70% or more (= porosity is less than 30%), more preferably 85% or more. As a result, the sintered body 3 can exhibit sufficient mechanical strength even in the rough portion 32 (that is, in its entirety).

Next, an embodiment of the method for producing a sintered body of the present invention will be described. [1] Synthesis of Hydroxyapatite and Preparation of Slurry Hydroxyapatite (HAp) is prepared, for example, by dropping an aqueous phosphoric acid (second raw material) solution into calcium hydroxide (first raw material) in a container (not shown). , Or a wet synthesis method such as a method of dropping an ammonium phosphate (second raw material) aqueous solution into a calcium nitrate (first raw material) aqueous solution and mixing them.

As described above, the synthesis of hydroxyapatite is preferably performed by a wet synthesis method using at least one of the first raw material and the second raw material as a solution.
As a result, hydroxyapatite can be synthesized more easily and efficiently without requiring expensive manufacturing equipment. At this time, the mixture in the container is in the form of slurry, for example.

In this embodiment, this slurry (mixture) is used.
1 is subjected to the next step [2]. As a result, the number of steps can be reduced (decreased), and the molded body 2 and thus the sintered body 3 can be manufactured more easily.

Prior to the next step [2], for example,
The content of hydroxyapatite (synthetic product) in the slurry 1 is adjusted by removal of liquid components after natural sedimentation, dehydration treatment, etc., and is preferably about 10 to 70 vol%, more preferably about 30 to 60 vol%. You may do it. This can prevent an increase in the amount of water (liquid component) separated when the slurry 1 is applied to the centrifuge. Therefore, there is an advantage that it is possible to prevent an increase in the size of the container to be placed in the centrifugal separator.

[2] Molding (Manufacture of Molded Body) First, as shown in FIG. 1 (a-1), the slurry 1 prepared in the step [1] is put into a molding die 10.

As the mold 10, for example, molds made of various resin materials, various metal materials and the like can be used.

In this embodiment, a pencil-shaped mold is used as the molding die 10. However, the molding die 10 is not limited to this, and the shape of the molding die 10 corresponds to the desired shape of the sintered body 3. Then, it may be set appropriately.

The size of the molding die 10 is determined in the next step [3].
It is appropriately set so that the molded body 2 having a size in consideration of shrinkage during firing can be obtained.

A releasing agent is preferably applied to the inner surface 11 of the molding die 10. Thereby, after the molded body 2 is obtained, the releasability of the molded body 2 from the molding die 10 can be improved.

The release agent is not particularly limited, and examples thereof include liquid paraffin and various waxes. Among them, in particular, in the baking in the next step [3],
Those that are thermally decomposed and removed (disappeared) are preferable. Specifically, liquid paraffin is preferably used. By using such a substance as a release agent, the sintered body 3
It is possible to prevent the release agent from remaining therein, and as a result, especially when the sintered body 3 is used as a biomaterial,
It is possible to preferably prevent the biosafety from decreasing.

Next, the molded body 2 is obtained (formed). As shown in FIG. 1 (a-2), this molding is performed by the molding die 10
Is installed in, for example, a centrifugal separator (not shown), and centrifugal force is applied to the mold 10.

As a result, the compound (hydroxyapatite: solid component) in the slurry 1 becomes unevenly distributed in the direction in which the centrifugal force acts, the molded body 2 is molded, and the rotational center 100 side of the molded body 2 ( On the left side in FIG. 1 (a-2), a liquid component 2 ′ other than the solid component is separated.

The rotation speed (centrifugal rotation speed) of the molding die 10 is not particularly limited, but is, for example, 2000 rpm.
It is preferable to set it as the above or more, and 2500-4000 rp
More preferably, it is about m. Thereby, the molded body 2
And the resulting sintered body 3 can exhibit sufficient mechanical strength.

Further, for the reasons described above, the sintered body 3
Preferably has a dense portion 31 and a rough portion 32. For this purpose, at the stage of obtaining the molded body 2, the molded body 2 may be molded so as to have the dense portion 21 and the rough portion 22.

Such a molded body 2 can be easily obtained by changing the rotation speed of the molding die 10 within the above range, for example, continuously or stepwise.

In this way, the rotation speed of the molding die 10 is changed continuously or stepwise, whereby the rotation center 10 is rotated.
On the side distant from 0 (the right side in FIG. 1 (a-2)), the density of the compound is high and a dense portion 21 is formed. At this time, the air (gas) contained in the slurry 1 is the center of rotation 1
By being pushed to the 00 side (the left side in FIG. 1 (a-2)), a high air content (low density) portion, that is, a rough portion 22 is formed on the rotation center 100 side of the molded body 2. To be done.

Rotational speed of this mold 10 (centrifugal rotation speed)
Can be changed, for example, in the patterns of to as shown in FIG. Further, the changing pattern of the rotation speed of the molding die 10 may be a combination of two or more arbitrary patterns of the above.

The changing pattern of the rotational speed of the molding die 10 is not limited to the pattern shown in FIG.

Further, it is preferable that an organic substance (binder) for adjusting the density is added to the slurry 1. Thereby, the density of the molded body 2 (sintered body 3) can be adjusted appropriately.

The organic substance is preferably slightly smaller than the specific gravity of the compound (hydroxyapatite). When the specific gravity of the organic substance is A and the specific gravity of the compound is B, A / B is, for example, , 0.2 to 0.85 is preferable, and 0.2 to 0.5 is more preferable. Due to the difference in the specific gravities of the organic substance and the synthetic substance, it is possible to more surely form coarse and dense in the molded body 2.
That is, the dense portion 21 and the rough portion 22 can be formed more reliably.

Further, it is more preferable that the organic substance is one which is thermally decomposed and removed (disappeared) by the firing in the next step [3]. Thereby, it is possible to prevent the organic substance from remaining in the sintered body 3, and as a result, it is preferable that the biosafety of the sintered body 3 is lowered particularly when the sintered body 3 is used as a biomaterial. Can be prevented.

Examples of such organic substances include methyl cellulose and starch.

In the slurry 1, the weight ratio of the organic substance to the synthetic substance is, for example, 0.1: 99.9 to 20: 8.
It is preferably added at about 0, and 1:99 to 5:
More preferably, it is added at about 95. If the amount of the organic substance added is too small, in the molded body 2, the rough portion 22
May not be formed efficiently. On the other hand, if the added amount of the organic substance is too large, a large amount of the organic substance exists in the molded body 2 depending on the specific gravity of the organic substance, and as a result, the mechanical strength of the obtained sintered body 3 is lowered. May be invited.

The molding temperature (molding temperature) is not particularly limited, but is preferably about 10 to 70 ° C. Usually, it may be about room temperature.

Further, the obtained molded body 2 may be dried by a method such as vacuum drying, natural drying, warm air drying, and freeze drying.

Next, as shown in FIG. 1A-3, the molded body 2 is taken out from the molding die 10 (released). At this time, since a mold release agent is applied to the inner surface 11 of the molding die 10, the mold is easily released, and the molded body 2 is preferably prevented from being deformed or damaged.

Further, when the molded body 2 is taken out from the molding die 10, the molding die 10 may or may not be divided.

The molded body 2 may be subjected to the next step [3] with the shape as it is after molding, but it may be subjected to mechanical processing such as cutting, cutting, grinding and polishing to obtain the shape. You may arrange it.

[3] Firing of molded body The molded body 2 molded as described above is fired, for example, in a furnace to obtain a sintered body 3 (see FIG. 1 (b)). When the molded body 2 is sintered, the molded body 2 shrinks, its size becomes smaller, and it becomes densified. At this time, the coarse portion 22 which is coarser than the dense portion 21 has a large shrinkage ratio, and the molded body 2 having a pencil shape has a shell-shaped sintered body 3.
Becomes

The temperature at the time of baking (baking temperature) is not particularly limited, but it is preferably 1000 ° C. or higher and lower than the temperature at which the synthetic substance is thermally decomposed. When the compound is hydroxyapatite, the temperature is preferably about 1000 to 1400 ° C, more preferably about 1050 to 1200 ° C.
If the firing temperature is too low, the density of the sintered body 3 may not be increased, and if the firing temperature is too high, thermal decomposition of the compound (hydroxyapatite) may occur, resulting in deterioration of the quality of the sintered body 3. May be invited.

The firing time is not particularly limited either,
When firing in the above temperature range, for example, it is preferably about 0.1 to 6 hours, more preferably about 2 to 4 hours.

When the composition is a calcium phosphate compound such as hydroxyapatite, the firing atmosphere is, for example, the atmosphere, oxygen gas, nitrogen gas, argon gas, or each atmosphere under reduced pressure. You can In the case of other compounds, the firing atmosphere can be, for example, under reduced pressure or in an inert gas such as argon gas, helium gas or nitrogen gas.

Although the method for producing a sintered body and the sintered body of the present invention have been described above with respect to the respective embodiments, the present invention is not limited to these.

For example, in the method for producing a sintered body of the present invention,
Any step can be added as needed.

[0081]

EXAMPLES Next, specific examples of the present invention will be described.

Example 1 A sintered body having a shape as shown in FIG. 1B was manufactured.

First, calcium hydroxide (first raw material) is hydrated, placed in a beaker, and a phosphoric acid (second raw material) aqueous solution is dropped into the beaker, which is sufficiently stirred and mixed to give hydroxyapatite. (Compound) was synthesized.

A mixture containing hydroxyapatite (specific gravity: 3.16 g / cm ³ ) in this beaker was used as a slurry.

By the dehydration treatment, the content of hydroxyapatite in the slurry was adjusted to 50 vol%.

Next, this slurry was molded into a pencil-shaped molding die made of polypropylene with the inner surface coated with liquid paraffin (release agent) (size: inner diameter 15 mm × maximum depth 50 m).
m). Then, this mold was placed in a centrifuge and rotated at room temperature for centrifugation. In addition,
This rotation was performed by maintaining the rotation speed at 3500 rpm for 15 minutes, discarding the supernatant water, and further rotating at 3500 rpm for 1 minute.
Hold for 5 minutes. This operation was repeated 4 times.

Next, each mold was placed in a dryer kept at 40 ° C. for 48 hours or more, and then the molded body was taken out from the mold.

Next, this molded body was placed in a dryer kept at 80 ° C. for 24 hours or more to be completely dried.

Thereafter, the portion of the molded body on the side of the center of rotation is approximately 5
%, And then fired in a furnace to obtain a shell-shaped sintered body. This firing was performed under the conditions of 1200 ° C. × 4 hours in the air.

The obtained sintered body had a relative density (average) of about 95% (porosity 5%).

Further, this sintered body was cut along a plane parallel to the direction in which centrifugal force acts, and the change in relative density (porosity) at this cut surface was observed with an electron microscope. as a result,
The relative density (porosity) was uniform as a whole.

(Example 2) A sintered body was produced in the same manner as in Example 1 except that the following changes were made.

In the slurry obtained in the same manner as in Example 1, methyl cellulose (specific gravity:
1.26 to 1.31 g / cm ³ ) was added. The weight ratio of this methyl cellulose to hydroxyapatite was set to 1:99.

Next, this slurry was put into a molding die.
Then, this mold was placed in a centrifuge and rotated at room temperature for centrifugation. The rotation speed was maintained at 3000 rpm for 15 minutes, after discarding the supernatant water, it was further maintained at 3000 rpm for 15 minutes. This operation was repeated 4 times.

Next, each molding die was placed in a dryer kept at 40 ° C. for 48 hours or more, and then the molded body was taken out from the molding die.

Next, this molded body was placed in a dryer kept at 80 ° C. for 24 hours or more to be completely dried.

After that, the portion of the molded body on the rotation center side is about 1
%, And then fired in a furnace to obtain a shell-shaped sintered body. This firing was performed under the conditions of 1200 ° C. × 4 hours in the air.

In the obtained sintered body, the relative density of the dense part was about 94% (porosity 6%), and the relative density of the rough part was about 90% (porosity 10%). The relative density (average) as a whole was about 92%.

Further, this sintered body was cut along a plane parallel to the direction in which centrifugal force acts, and the change in relative density (porosity) at this cut surface was observed with an electron microscope. as a result,
The relative density (porosity) continuously changed from the dense portion to the coarse portion.

Example 3 A sintered body was manufactured in the same manner as in Example 1 except that the following changes were made.

The slurry obtained in the same manner as in Example 1 was put in a molding die. Then, this mold was placed in a centrifuge and rotated at room temperature for centrifugation.
In this rotation, the rotation speed was maintained at 3000 rpm for 15 minutes, and after discarding the supernatant water, further rotation was performed at 3000 rpm.
For 15 minutes. Then, the rotation speed is 200 rpm /
It is continuously decreased at a rate of 10 minutes for 10 minutes, and then
The rotation was performed at 1000 rpm for 5 minutes.

Next, each molding die was placed in a dryer kept at 40 ° C. for 48 hours or more, and then the molding was taken out from the molding die.

Next, this molded body was placed in a dryer kept at 80 ° C. for 24 hours or more to completely dry it.

After that, the portion on the rotation center side of the molded body is moved to about 1
%, And then fired in a furnace to obtain a shell-shaped sintered body. This firing was performed under the conditions of 1200 ° C. × 4 hours in the air.

The obtained sintered body had a relative density of about 97% (porosity 3%) in a dense portion and a relative density of about 92% (porosity 8%) in a rough portion. The relative density (average) as a whole was about 95%.

The sintered body was cut along a plane parallel to the direction in which the centrifugal force acts, and the change in relative density (porosity) at this cut surface was observed with an electron microscope. as a result,
The relative density (porosity) continuously changed from the dense portion to the coarse portion.

[0107]

As described above, according to the present invention, it is possible to obtain a sintered body that can be used as, for example, an artificial tooth root or a bone filling material, by a simple method utilizing centrifugal force.

As a result, the manufacturing cost of the sintered body is reduced,
The manufacturing time can be shortened.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a method for manufacturing a sintered body of the present invention.

FIG. 2 is a diagram showing a change pattern of centrifugal rotation speed.

[Explanation of symbols]

1 slurry 2 molded body 2'liquid component 21 dense part 22 Coarse part 3 Sintered body 31 dense part 32 Coarse part 10 Mold 11 Inside 100 center of rotation

Claims (17)

[Claims] 1. A step of obtaining a molded article by mixing a first raw material and a second raw material, putting a slurry containing a compound obtained by reacting them into a molding die, and applying a centrifugal force. And a step of obtaining a sintered body by firing the molded body, the method for producing a sintered body. 2. The method for producing a sintered body according to claim 1, wherein at least one of the first raw material and the second raw material is used as a solution. 3. The method for producing a sintered body according to claim 1, wherein the centrifugal rotation speed is continuously or stepwise changed to change the density of the compact in the direction in which the centrifugal force acts. 4. A step of placing a slurry containing a compound in a molding die and applying a centrifugal force to obtain a molded body having a portion whose density changes in the direction in which the centrifugal force acts, and firing the molded body. And a step of obtaining a sintered body by doing the above. 5. The method for producing a sintered body according to claim 4, wherein the density of the molded body is changed by continuously or stepwise changing the centrifugal rotation speed. 6. The method for producing a sintered body according to claim 4, wherein the composite is obtained by mixing the first raw material and the second raw material and reacting them. 7. The method for producing a sintered body according to claim 6, wherein the slurry is obtained when the first raw material and the second raw material are mixed. 8. The method for producing a sintered body according to claim 6, wherein at least one of the first raw material and the second raw material is used as a solution. 9. The method for producing a sintered body according to claim 1, wherein an organic substance for adjusting the density of the molded body is added to the slurry. 10. When the specific gravity of the organic substance is A and the specific gravity of the composite is B, A / B is 0.2 to 0.85.
10. The method for manufacturing a sintered body according to claim 9. 11. The method for producing a sintered body according to claim 1, wherein a release agent is applied to the inner surface of the molding die. 12. The method for producing a sintered body according to claim 1, wherein the firing temperature is 1000 ° C. or higher and lower than the temperature at which the composite is thermally decomposed. 13. The method for producing a sintered body according to claim 1, wherein the sintered body has a relative density of 70% or more. 14. The method for producing a sintered body according to claim 1, wherein the composite is a ceramic material. 15. The method for producing a sintered body according to claim 14, wherein the ceramic material is a calcium phosphate-based compound. 16. The method for producing a sintered body according to claim 15, wherein the calcium phosphate-based compound is hydroxyapatite. 17. A sintered body produced by the method for producing a sintered body according to any one of claims 1 to 16.