JP2002249373A - Spherical apatite ceramics and method for producing the same - Google Patents

Abstract

[PROBLEMS] To provide a spherical apatite ceramic and a method for producing the same. SOLUTION: A method of manufacturing apatite ceramics obtained by sintering an apatite green compact of an arbitrary shape, moving the apatite ceramics along the inner wall of a circular chamber by air pressure, forming the spherical shape by abrasion, and And a method for producing spherical apatite ceramics by moving and abrading an apatite green compact having an arbitrary shape along the inner wall of a circular chamber by air pressure to form a spherical shape, followed by firing to form a spherical apatite ceramic. [Effect] A spherical hydroxyapatite having a desired diameter, strength, and surface properties can be easily and efficiently produced, and the obtained spherical apatite ceramic is made of titanium or titanium alloy such as an artificial root or an artificial joint stem. It can be suitably used in the fields of improving the bioactivity of the surface of an implant, the surface of an indwelling device such as an artificial heart and a pacemaker, and a filler for a bone defect, a drug carrier, and a column filler.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spherical apatite ceramics and a method for producing the same, and more particularly, to a method in which apatite ceramics or apatite green compact prepared by an arbitrary method is coated on an inner wall with arbitrary abrasive grains. The present invention relates to a method for easily and efficiently forming a sphere by using a circular chamber device and a spherical apatite ceramic. The spherical apatite ceramics of the present invention can be used to improve the bioactivity of titanium and titanium alloy implant surfaces, such as artificial roots and artificial joint stems, and the in vivo indwelling devices, such as artificial hearts and pacemakers, as well as filling bone defects. It is useful as a material that can be suitably used in the fields of various medical materials such as agents and drug carriers, filtration materials, column packing materials and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for producing spherical apatite ceramics, a spray drying method (for example,
JP-A-8-020802), a gel capsule method (for example,
JP-A-5-177156) and the rolling granulation method (for example, JP-A-2000-140603) are known. Among them, the spray drying method is a method in which a slurry is sprayed and dried in an air stream dried at a high temperature to form spherical granules of about several tens of microns. In the gel capsule method, a raw material powder dispersed in an aqueous sodium alginate solution or the like that gels with polyvalent metal ions is dropped into a coagulating liquid in which the polyvalent metal ions are dissolved, and the surface of the droplet is dropped. This is a method of forming into a sphere by gelation. Further, the rolling granulation method is a method in which an inclined cylinder containing a raw material powder and a binder is rotated to form spherical particles. However, the spray drying method can provide a spherical ceramic having good strength, but has a problem that it is difficult to produce a sphere having a particle size of 100 μm or more. In addition, in the gel capsule method and the tumbling granulation method, it is possible to produce a relatively large sphere, but it is difficult to densify the obtained spherical ceramic, and to obtain a spherical ceramic having good strength. There is a problem that is difficult. Further, the gel capsule method has a problem that cations in the coagulation liquid are easily replaced by elements in apatite, and it is difficult to obtain a spherical apatite ceramic having a single composition.

[0003] In recent years, in order to improve the fixation of titanium and titanium alloy implants such as artificial dental roots and artificial joint stems to bones, a technique for fixing apatite ceramics directly bonded to bones on the implant surface has been studied in the dental field. Is being promoted. Apatite ceramics are fixed to the implant surface using sandblasting, superplasticity of titanium alloy, and plasma spraying. When apatite ceramics are fixed by using sandblasting or superplasticity of a titanium alloy, the apatite ceramics are required to have a strength higher than the deformation resistance of titanium and a titanium alloy, and a spherical shape is desirable. In order to perform highly controlled fixing of the titanium alloy using the superplastic phenomenon, spherical ceramics of several hundred microns which are easy to handle are suitable. Further, when used as a filler for a bone defect, spherical apatite ceramics having a particle size of several hundred microns can secure a sufficient blood clot in the voids and can be expected to rapidly heal wounds. In plasma spraying, it is appropriate to use relatively high-strength apatite granules having a size of 80 μm or more to obtain a sprayed apatite film having a desired composition. In addition, granules having a particle size of 30 μm or more are suitable for apatite ceramics for separation and purification. However, in order to enable use at a higher flow rate, it is desired to increase the strength of the granules. Thus, heretofore, in the art, there has been a strong demand for the development of a method capable of increasing the density and strength of apatite granules having a desired particle size.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a spherical apatite ceramic having desired strength, density and particle size in view of the above-mentioned background. That is, the present invention, any particle size, compressive strength,
An object of the present invention is to provide a new method for producing spherical apatite ceramics, which enables efficient production of spherical apatite ceramics having a density and surface properties by simple operations. Another object of the present invention is to provide a spherical apatite ceramic having the above characteristics, which is produced by the above method. Further, the present invention provides a method for controlling the density and strength of the obtained spherical apatite ceramics by arbitrarily setting the conditions of the compacting and sintering in the above method, and the molding conditions and time for forming the spherical shape. It is intended to provide a method of controlling the surface properties and the particle size of the obtained spherical apatite ceramics by arbitrarily setting.

[0005]

The present invention for solving the above-mentioned problems comprises the following technical means. (1) A powder compact obtained by compacting the raw material apatite into an arbitrary shape is crushed as it is or to an appropriate size, and is moved by air pressure along the inner wall of a circular chamber in which arbitrary abrasive grains are coated on the inner wall. A method for producing spherical apatite ceramics, which comprises abrading, forming into a spherical shape, and then sintering. (2) After sintering the green compact obtained by compacting the raw material apatite into an arbitrary shape, it is crushed as it is or to an appropriate size, and along the inner wall of a circular chamber in which an arbitrary abrasive is coated on the inner wall. A method for producing spherical apatite ceramics, wherein the spherical apatite ceramic is formed by moving and abrading by air pressure to form a spherical shape. (3) The method for producing spherical apatite ceramics according to (1) or (2), wherein the raw material apatite is one selected from hydroxyapatite, carbonate apatite, fluorapatite, and chlorapatite, or a mixture thereof. . (4) A spherical apatite ceramic which is obtained by compacting and sintering by the method according to any one of the above (1) to (3) and which is excellent in spherical and compressive strength.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In order to achieve the above object, in the present invention,
After apatite is compacted by a method that can obtain the desired characteristics, it is sintered and densified, and is pneumatically moved along the inner wall of a circular chamber coated with arbitrary abrasive grains on the inner wall to form a sphere. It is characterized by doing. Further, in the present invention, after apatite is compacted by a method capable of obtaining desired properties, apatite is formed into a spherical shape by moving it by air pressure along the inner wall of a circular chamber coated with arbitrary abrasive grains. It is characterized by sintering and densification to obtain spherical particles. Therefore, the apatite ceramics and the green compact are pneumatically moved along the inner wall of the circular chamber, and are abraded and formed into a spherical shape. In this case, the particle size of the spherical apatite ceramics is
It can be controlled by increasing or decreasing the molding time. Further, the density and strength of the obtained spherical apatite ceramics can be controlled by compacting and sintering performed before forming into a spherical shape. In other words, in the present invention, before the object to be formed is processed into a spherical shape, a uniaxial working, a cold isostatic pressing (CI)
It is possible to easily and arbitrarily control the density and strength of the obtained spherical apatite ceramics by increasing the density and strength to an arbitrary level by P) and hot isostatic pressing (HIP) or the like. The surface characteristics of the obtained spherical apatite ceramics can be controlled by the surface roughness of the inner wall of the circular chamber. Apatite used in the present invention have the general formula Ca10 (PO _{4) 6}
X ₂ (X in the formula is a hydroxyl group, halogen, or the like), and among them, one selected from hydroxyapatite, carbonate apatite, fluorapatite, and chlorapatite, or a mixture thereof has biocompatibility and adsorption characteristics. It is suitable in this respect.
The apatite may be a natural mineral or may be synthesized by various wet or dry methods, but is preferably a powder having a BET value of about 1 to 300 m ² / g.

The compacting of apatite may be carried out, for example, by uniaxial pressing at about 1 to 3000 kg / cm ² or 1000 to 10000, depending on the use of the spherical apatite.
Cold isostatic pressing (CIP) at about kg / cm ² may be used. It is also possible to appropriately mold by hot isostatic pressing (HIP). Further, the porosity of the obtained spherical apatite ceramics can be controlled by appropriately selecting the binder. For example, when used for press-fitting to the titanium surface, it is molded by CIP without using a binder to achieve densification, and when a relatively large surface area such as a drug carrier or a filter material is required, the binder is used. It can be appropriately selected such as using a porous body manufactured by using such a method.

When the apatite green compact or ceramics is formed into a spherical shape, the internal pressure applied in the circular chamber is 1
Desirably, the weight is not less than kg / cm ^{2 and not} more than 20 kg / cm ² . Further, the apatite green compact or the ceramic can be crushed to an arbitrary size and formed into an appropriate size, if necessary. It is convenient to use a compressor to pressurize the inside of the circular chamber, but an appropriate one can be used. Further, as abrasive grains coated on the inner wall of the circular chamber, diamond abrasive grains are desirable in terms of durability, biological synthesis, and the like, but not limited thereto, and appropriate types of abrasive grains can be used.
The number of the abrasive grains may be appropriately selected from the desired surface roughness, processing time, durability of the green compact, and the like. The sintering of the green compact is preferably performed at 900 to 1200 ° C.

The spherical apatite ceramics obtained by the present invention can be obtained by appropriately selecting the processing conditions.
It can have a diameter of 0-1000 μm. Further, depending on the method of preparing the green compact, the powder may have a compressive strength of 50 to 500 MPa. For example, apatite ceramics having a size of about 1 mm formed by uniaxial pressing and baked at 1000 ° C. for 1 hour are processed at an internal pressure of 1 kg / cm ² for 30 minutes in a circular chamber electrodeposited with # 600 diamond abrasive grains. By doing so, spherical apatite ceramics having a diameter of 500 μm and a compressive strength of 500 MPa can be obtained. In the present invention, before the object to be formed is processed into a spherical shape, it is compacted by means of uniaxial pressing, cold isostatic pressing (CIP), hot isostatic pressing (HIP), or the like. It is possible to arbitrarily control the density and strength of the apatite ceramics to increase the density and the strength, thereby making it possible to produce spherical apatite ceramic granules having a desired particle size, density and strength by a relatively simple operation. It can be easily manufactured.

[0010]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Example 1 0.5 mol / l calcium hydroxide suspension was added to 0.5 mol / l
Hydroxyapatite powder wet-synthesized by dropwise addition of a phosphoric acid aqueous solution of mol / l was uniaxially pressed into a cylindrical shape of φ16 × 6 mm, and then sintered at 1200 ° C. for 1 hour.
This sintered body has a total body density of 90% and a compressive strength of 400 MPa.
Met. This sintered body is roughly crushed, and
m. That is, after passing through a 850 μm mesh sieve to remove particles of 850 μm or more, 600 μm
The particles having a size of 600 μm or less were removed through a mesh sieve.
Sintered particles of 600 to 850 μm were formed into a spherical shape by rotating at a pressure of 1 kg / cm ² in a circular chamber having # 800 diamond abrasive grains coated on the inner wall. FIG. 1 shows the circular chamber used in this embodiment. By such a molding method, the total density is 90% and the compressive strength is 4%.
A 00 MPa spherical hydroxyapatite ceramic was produced. The spherical apatite ceramics produced by the method of the present invention was able to be press-fitted at 900 ° C. without damaging the surface of pure titanium.

Example 2 A hydroxyapatite powder obtained in the same manner as in Example 1 was mixed with a mixed solution (binder solution) of 3 wt% of polyvinyl alcohol and 1 wt% of polyethylene glycol of the same weight as the hydroxyapatite powder. After mixing, drying and grinding, 10MP
a) Cold isostatic pressing (CIP) was performed to obtain a hydroxyapatite green compact. This green compact is crushed into an irregular shape having a size larger than the desired bead particle size, and the inner wall is rotated at an air pressure of 1 kg / cm ² in a circular chamber having a surface roughness of 0.8 to form a spherical shape. (Fig. 1). By such a molding method, a spherical hydroxyapatite green compact was produced. This spherical green compact was sintered at 1200 ° C. for 1 hour to obtain a spherical hydroxyapatite ceramic. The spherical apatite ceramics produced by the method of the present invention was able to be press-fitted at 900 ° C. without damaging the surface of pure titanium.

Comparative Example 10 g of hydroxyapatite powder obtained in the same manner as in Example 1.
Was mixed with 1 g of sodium alginate (900 g) and dropped into 1 wt% of calcium chloride (coagulating liquid) at a nozzle vibration frequency of 100 Hz to obtain spherical apatite gel capsules. After drying this gel capsule, 120
Sintering was performed at 0 ° C. for 1 hour to obtain a spherical hydroxyapatite ceramic having a diameter of 300 to 400 μm. The spherical apatite ceramics obtained by this molding method was a porous body, had a breaking load of 0.75 kgf, and could not be pressed into the surface of pure titanium at 900 ° C.

[0013]

According to the present invention, the following effects can be obtained. (1) In the present invention, it is possible to increase the density and the strength by uniaxial pressing, cold isostatic pressing (CIP), hot isostatic pressing (HIP), etc., before processing the object into a spherical shape. Therefore, it is easier to increase the density and strength of the obtained spherical ceramic as compared with other methods for manufacturing a spherical ceramic. (2) Further, the desired surface properties can be easily obtained by finishing the surface roughness of the inner wall of the circular chamber or changing the number of diamond abrasive grains to be coated as required. (3) The particle size of the spherical apatite ceramics can be controlled by increasing or decreasing the molding time. (4) The spherical apatite ceramics of the present invention can be used to improve the bioactivity of the surface of an implant made of titanium or a titanium alloy such as an artificial tooth root or an artificial joint stem, the surface of an indwelling device such as an artificial heart or a pacemaker, or a bone defect. It can be suitably used in the field of various medical materials such as fillers for pharmaceuticals, drug carriers, and column fillers.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a circular chamber used for forming ceramics of an arbitrary shape into a sphere in the present invention.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tetsuya Kameyama 2761-1394 Obata Kitayama, Moriyama-ku, Nagoya-shi, Aichi Prefecture ) Inventor Kiyoaki Tanaka 112-883, Ashima-ma, Iwasaki-cho, Nisshin-shi, Aichi (72) Inventor Takayuki Tsuchida 3-4-21-704, Kasubekahigashi, Kasukabe-shi, Saitama F-term (reference) 4G030 AA08 AA41 BA20 BA35 CA07 GA19 GA22 GA32

Claims (4)

[Claims] A powder compact obtained by compacting a raw material apatite into an arbitrary shape is crushed as it is or to an appropriate size.
A method for producing spherical apatite ceramics, wherein the spherical apatite ceramic is formed by moving and abrading by air pressure along the inner wall of a circular chamber in which arbitrary abrasive grains are coated on the inner wall, forming the spherical shape, and then sintering. 2. An inner wall of a circular chamber in which a raw material apatite is formed into an arbitrary shape by sintering and then crushed as it is or crushed to an appropriate size to coat arbitrary abrasive grains on the inner wall. Move pneumatically along the
A method for producing spherical apatite ceramics, which is formed into a spherical shape. 3. The method according to claim 1, wherein the raw material apatite is hydroxyapatite,
The method for producing spherical apatite ceramics according to claim 1 or 2, wherein the method is one selected from carbonate apatite, fluoroapatite, and chlorapatite, or a mixture thereof. 4. A spherical apatite ceramic produced by the method according to any one of claims 1 to 3, wherein the green compact or a sintered body thereof is coated with arbitrary abrasive grains on an inner wall of a circular chamber. Moving pneumatically along the inner wall,
Spherical apatite ceramics having excellent compressive strength, obtained by abrasion, forming into a spherical shape, and sintering the above-mentioned green compact.