JP3463106B2 - Spherical apatite ceramics and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to spherical apatite ceramics and a method for producing the same. More specifically, the inner wall of apatite ceramics or apatite green compact prepared by any method is coated with any abrasive grains. The present invention relates to a method for easily and efficiently forming a spherical shape using a circular chamber device and a spherical apatite ceramics. The spherical apatite ceramics of the present invention improve the bioactivity of implant surfaces made of titanium and titanium alloys such as artificial tooth roots and artificial joint stems, and the surfaces of indwelling devices such as artificial hearts and pacemakers, and fill 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, filtering materials, and column packing materials.

[0002]

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

In recent years, for the purpose of improving fixation of titanium and titanium alloy implants such as artificial tooth roots and artificial joint stems to bone, a method of fixing apatite ceramics directly bonded to bone on the implant surface has been studied in the dental field. Is being promoted. Apatite ceramics are fixed to the implant surface by utilizing sandblasting, superplasticity phenomenon of titanium alloy, and plasma spraying. When apatite ceramics are fixed by sandblasting or utilizing the superplasticity phenomenon of titanium alloy, the apatite ceramics are required to have strength higher than the deformation resistance of titanium and titanium alloys, and the shape is preferably spherical. In addition, spherical ceramics of several hundreds of microns that are easy to handle are suitable for highly controlled fixation of titanium alloys using superplasticity. Further, when used as a filling material for a bone defect, spherical apatite ceramics having a particle size of several hundreds of micron can secure a sufficient blood clot in the void, and rapid wound healing can be expected. In plasma spraying, in order to obtain an apatite sprayed film having a desired composition, it is appropriate to use relatively high strength apatite granules having a size of 80 μm or more as a raw material. Further, for the apatite ceramics for separation and purification, granules having a particle size of 30 μm or more are suitable, but in order to enable use at a higher flow rate, higher strength of the granules is desired. As described above, conventionally, there has been a strong demand in the technical field for development of a method capable of increasing the density and strength of apatite granules having a desired particle size.

[0004]

SUMMARY OF THE INVENTION In view of the background described above, the present invention has been made to provide spherical apatite ceramics having desired strength, density and particle size. That is, the present invention, any particle size, compressive strength,
It is an object of the present invention 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 a simple operation. 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, in the above method, by optionally setting the conditions of compacting and sintering, the method for controlling the density and strength of the obtained spherical apatite ceramics, and the molding conditions and time for forming the spherical shape It is intended to provide a method for controlling the surface properties and the particle size of the obtained spherical apatite ceramics by arbitrarily setting them.

[0005]

The present invention for solving the above-mentioned problems comprises the following technical means. (1) A compact, which is obtained by compacting raw material apatite into an arbitrary shape, is crushed as it is or into an appropriate size, and is pneumatically moved along an inner wall of a circular chamber in which an inner wall is coated with arbitrary abrasive grains, A method for producing spherical apatite ceramics, which comprises abrading, shaping into a spherical shape, and then sintering. (2) Along the inner wall of the circular chamber in which the inner wall is coated with arbitrary abrasive grains after sintering the green compact obtained by compacting the raw material apatite into an arbitrary shape A method for producing spherical apatite ceramics, characterized in that the spherical apatite ceramics are formed by moving and abrading with 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, fluoroapatite, chlorine apatite, or a mixture thereof. . (4) Spherical apatite ceramics obtained by compacting and sintering by the method according to any one of (1) to (3) above and having excellent compressive strength.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. In order to achieve the above object, in the present invention,
Apatite is compacted by a method that achieves the desired characteristics, then sintered and densified, and then pneumatically moved along the inner wall of a circular chamber where the inner wall is coated with any abrasive grains to form a spherical shape. It is characterized by doing. Further, in the present invention, after compacting the apatite by a method capable of obtaining desired characteristics, a spherical shape is obtained by moving pneumatically along the inner wall of a circular chamber in which any abrasive grain is coated on the inner wall. It is characterized in that it is bound and densified to obtain spherical particles. Therefore, the apatite ceramics and the green compact are moved by air pressure along the inner wall of the circular chamber, 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 the spherical apatite ceramic. That is, in the present invention, uniaxial processing, 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 the strength to an arbitrary level using P) and hot isostatic pressing (HIP). The surface characteristics of the obtained spherical apatite ceramics can be controlled by the surface roughness of the inner wall of the circular chamber. The apatite used in the present invention has the general formula Ca10 (PO ₄ ) ₆
It is represented by X ₂ (X in the formula is a hydroxyl group, halogen, etc.), and among them, one selected from hydroxyapatite, carbonate apatite, fluoroapatite, chlorine apatite, or a mixture thereof has biocompatibility and adsorption properties. It is suitable in that respect.
The apatite may be a natural mineral or may be one synthesized by various wet methods or dry methods, but it is preferably a powder having a BET value of about 1 to 300 m ² / g.

Apatite powder compacting may be carried out by uniaxial pressure molding at, for example, about 1 to 3000 kg / cm ² , depending on the use of spherical apatite, or from 1000 to 10000.
Cold isostatic pressing (CIP) may be performed at about kg / cm ² . Moreover, it is also possible to appropriately perform molding by a hot isostatic press (HIP). Moreover, the porosity of the obtained spherical apatite ceramics can be controlled by appropriately selecting the binder. For example, when it is used for press-fitting on the surface of titanium, it is formed by CIP without using a binder for densification, and when a relatively large surface area such as a drug carrier or a filtering material is required, the binder is It is possible to appropriately select such that a porous body produced by using is used.

The internal pressure applied to the circular chamber when the apatite green compact or ceramic is molded into a spherical shape is 1
It is desirable to be not less than kg / cm ^{2 and not} more than 20 kg / cm ² . Further, the apatite green compact or ceramics can be crushed into an arbitrary size and formed into an appropriate size, if necessary. For the pressurization in the circular chamber, it is convenient to use a compressor, but an appropriate one can be used. Further, the abrasive grains coated on the inner wall of the circular chamber are preferably diamond abrasive grains in terms of durability, biosynthesis, etc., but not limited thereto, and appropriate types of abrasive grains can be used.
Further, the abrasive grain may be selected from a suitable count in view of desired surface roughness, processing time, durability of the green compact and the like. Sintering of the green compact is preferably performed at 900 to 1200 ° C.

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

[0010]

EXAMPLES The present invention will now be described in detail based on examples, but the present invention is not limited to these examples. Example 1 To a 0.3 mol / l calcium hydroxide suspension, 0.5
Hydroxyapatite powder that was wet-synthesized by dropping a mol / l phosphoric acid aqueous solution was uniaxially pressure-molded into a cylindrical shape of φ16 × 6 mm, and then sintered at 1200 ° C. for 1 hour.
This sintered body has a total density of 90% and a compressive strength of 400 MPa.
Met. This sintered body is roughly crushed to 600-850μ
Aligned to the size of m. That is, after 850 μm mesh sieve to remove particles of 850 μm or more, 600 μm
The particles of 600 μm or less were removed by sieving with a mesh.
Sintered body particles of 600 to 850 μm were formed into a spherical shape by rotating at a pneumatic pressure of 1 kg / cm ² in a circular chamber whose inner wall was coated with # 800 diamond abrasive grains. The circular chamber used in this example is shown in FIG. With such a molding method, the overall density is 90% and the compression strength is 4
A 00 MPa spherical hydroxyapatite ceramic was produced. The spherical apatite ceramics produced by the method of the present invention could be pressed into the pure titanium surface at 900 ° C. without damage.

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

Comparative Example 10 g of hydroxyapatite powder obtained in the same manner as in Example 1
Was mixed with 900 g of 1 wt% sodium alginate and dropped into 1 wt% calcium chloride (coagulating liquid) at a nozzle vibration frequency of 100 Hz to obtain spherical apatite gel capsules. After drying the gel capsule, 120
Sintering was performed at 0 ° C. for 1 hour to obtain spherical hydroxyapatite ceramics 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 pure titanium surface 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 forming a molding object into a spherical shape. Therefore, it is easier to increase the density and strength of the obtained spherical ceramics as compared with other methods for producing spherical ceramics. (2) Furthermore, the desired surface texture can be easily obtained by changing the surface roughness of the inner wall of the circular chamber or changing the number of diamond abrasive grains to be coated, depending on the purpose and need. (3) Further, 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 improve the bioactivity of implant surfaces made of titanium and titanium alloys such as artificial tooth roots and artificial joint stems, and the surface of indwelling devices such as artificial hearts and pacemakers, as well as bone defect parts. It can be suitably used in the fields of various medical materials such as fillers for drugs, drug carriers, and column packing materials.

[Brief description of drawings]

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

Front Page Continuation (72) Inventor Tetsuya Kameyama 2761-1394 Obatakitayama, Moriyama-ku, Nagoya, Aichi (72) Inventor Katsuyoshi Naganuma 3-2-4 Kita-chikusa, Chikusa-ku, Nagoya-shi 17-403 (72) Inventor Kiyoaki Tanaka 112-883 (72) Inventor Takayuki Tsuchida, Iwasaki-cho, Nisshin-shi, Aichi Prefecture 3-4-21-704 (56) Kasubehigashi, Kasukabe-shi, Saitama Reference 56-206433 (JP, A) Kaihei 8-26722 (JP, A) JP-A-9-157002 (JP, A) JP-A-4-156935 (JP, A) JP-B 47-30511 (JP, B1) (58) Fields investigated ( Int.Cl. ⁷ , DB name) C04B 35/447

Claims (4)

(57) [Claims] 1. A green compact obtained by compacting raw material apatite into an arbitrary shape is crushed as it is or into an appropriate size,
A method for producing spherical apatite ceramics, which comprises moving an abrasive along an inner wall of a circular chamber having an inner wall coated with arbitrary grains by air pressure to cause abrasion, form a spherical shape, and then sinter. 2. An inner wall of a circular chamber in which an inner wall is coated with arbitrary abrasive grains after sintering a green compact obtained by compacting raw material apatite into an arbitrary shape and then sintering the powder compact. Pneumatically move along and wear
A method for producing spherical apatite ceramics, which is characterized by forming into a spherical shape. 3. Apatite as a raw material is hydroxyapatite,
The method for producing spherical apatite ceramics according to claim 1 or 2, which is one selected from carbonate apatite, fluoroapatite, chlorine apatite, or a mixture thereof. 4. A spherical apatite ceramic produced by the method according to any one of claims 1 to 3, comprising a circular chamber in which the inner wall of the green compact or its sintered body is coated with arbitrary abrasive grains. Pneumatically move along the inner wall,
Spherical apatite ceramics, which are spherical and have excellent compressive strength, which are obtained by abrading and shaping into a spherical shape, and in the case of the above-mentioned green compact, are sintered.