KR950010812B1 - Process for the preparation of sintering apatite ceramics - Google Patents

Abstract

The porous calcium phosphate ceramics sintered body is manufactured by calcinting a desirable amount of an apatite hydroxide powder of 10-20 micrometer average particle diameter at 700-1200 deg.C. to make a calcinted powder, adding 10-50 wt.pts(parts) of the apatite hydroxide powder to the calcinted powder, mixing them in the ball mill, molding the mixed powder in the metal mold at 400-800 kg/cm2 pressure, and sintering the molded article at 1050-1350 deg.C. The sintered body has 0.01-10 micrometer averge pore diameter and 5-40 vol.% porosity, and is used as a biomedical material.

Description

Method for manufacturing sintered calcium phosphate porous ceramics

1 is a graph showing the shrinkage rate with respect to the firing temperature of the basic raw material powder, calcined powder and mixed powder,

Figure 2a is a cross-sectional view showing the molding state of the base material powder particles and the calcined powder particles,

2b is a cross-sectional view showing the sintering state of the basic raw material powder particles and the calcined powder particles,

3 is an electron micrograph of a sintered calcium phosphate-based ceramic ceramics prepared according to the present invention.

* Explanation of symbols for main parts of the drawings

1: Basic powder 2: Calcined powder

3: mixed powder 4: basic powder particles

5: calcined powder particles 6: pores

The present invention relates to a method for producing a calcium phosphate-based porous ceramics, in particular, filling the bone defects and voids of the living body to promote the formation of new bone, and fine pore diameter useful as a biomaterial that is integrated with the bone tissue of the living body is properly controlled The present invention relates to a method for producing calcium phosphate porous ceramics.

In case of bone damage caused by an accident, disease or extraction, the filling of bone defects or voids is necessary. In this case, as the bone preservation material conventionally used, metal materials such as stainless steel, titanium and titanium alloys, or polymer materials such as silicone resins are used. There is no binding to, and in some cases, the melt is toxic due to dissolution or deterioration.

Therefore, there is a need for a material having excellent affinity and binding property, not to mention nontoxic to biological tissues. The ceramic material attracts attention as being able to satisfy this. Among them, calcium phosphate-based ceramics are in the spotlight due to the same components as bones, which have excellent affinity with bones and thus form chemical bonds with bones. Examples of calcium phosphate ceramics include apatite hydroxide [Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ], β-tricalcium phosphate [β-Ca ₃ (PO ₄ ) ₂ ], and the like.

However, in the case of using a bone preservation material made of calcium phosphate-based material, there is a problem when it is filled in vivo because the living body judges the biological material as a foreign material and exhibits a foreign body reaction. In general, the filled bone preservatives adhere to the new bone at the part close to the living tissue, but at the part far away from the living tissue, the bone preservatives are surrounded by the fibrous tissue and softened by the so-called capsule reaction. As described above, when calcium phosphate-based materials are used, tissue incompatibility due to the capsule reaction occurs at sites where healing power is not active.

In order to solve this problem, Japanese Laid-Open Patent Publication No. 63-125,258 proposes that at least 30% or more of the apparent surface area of the hydroxide apatite granules have irregularities of 1 µm or more. However, even when manufactured by this method, it is found that it is difficult to completely suppress the foreign body reaction of a living body, and part of the range of use as a bone preservation material is limited.

Japanese Laid-Open Patent Publication No. 62-281,953 focuses on the phenomenon that occurs when the bone preservatives filled in vivo are judged to be foreign substances. As a result, when the body fluid is flowing at the site where macrophages are attached, It was found that the capsule reaction can be prevented without judging the foreign matter by the cells and solved by forming continuous pores having a diameter of 0.01 to 10 μm in the bone preservative. In particular, when the average pore diameter of the bone preservation material is 0.01 ~ 1㎛ said that there is an effect of preventing the capsule by the macrophages.

However, looking at the manufacturing method of Japanese Patent Application Laid-open No. 62-281,953, in order to form pores of 0.01 to 10 ㎛, combustible organic particles, for example, fine particles of polystyrene, polyvinyl alcohol, or polypropylene resin are wetted with apatite hydroxide and wet type. After mixing, drying and pulverizing, it is proposed a method of burning off the internal combustible organic material through a firing process. However, if this method is used, there is no problem in pore formation but a problem may occur in the distribution of pores existing in the porous body. In order to dry after wet mixing, the mixed sample in the nitric state is left to stand in the dryer for a long time. At this time, the specific gravity between the apatite hydroxide (specific gravity 3.156) and the combustible organic substance (specific polypropylene specific gravity 0.90 to 0.91, specific polystyrene 1.05 to 1.06) Due to the difference, light flammable organic matter rises, which causes nonuniformity in the pore distribution of the porous body.

In addition, although the flammable organic material is removed through the firing process, there is a fear of contamination, and mixing the flammable organic material is not economically advantageous.

Therefore, the present invention is a calcium phosphate-based porous ceramics sintered body that is a bone preservation material to prevent the encapsulation reaction is well adhered to the new bone even in areas where the healing power is not active due to evenly distributed micro pores evenly from the biological tissue It is an object to provide a method.

In addition, an object of the present invention is to provide an economical manufacturing method without fear of contamination by organic pore-forming agents.

The present invention is described in detail as follows.

The present invention spray-dried the average particle diameter of about 50mm prepared by wet precipitation method to make a basic raw material powder having an average particle diameter of about 10 to 20㎛, take a certain amount of the powder and calcinate at about 700 to 1200 ℃ A calcined powder was prepared by treatment, and the base raw material powder was added and mixed at a ratio of about 10 to 50% by weight, and then molded and sintered to have a pore diameter of about 0.01 to about 10 µm. It is a method for producing a calcium phosphate porous ceramic sintered body having a porosity of from 40% by volume to 40% by volume.

Hereinafter, the present invention will be described in more detail.

Phosphoric acid is reacted with a calcium hydroxide suspension to produce an apatite hydroxide precipitate having an average particle diameter of about 50 mm by wet precipitation so as to have a Ca / P molar ratio of about 1.60 to 1.67. The prepared 50mm particle size of the apatite hydroxide has a hydroxyl group (OH), the apatite hydroxide particles have a property of adsorbing moisture on the surface or inside the particles due to the large specific surface area (about 100㎡ / g).

Subsequently, in order to maintain this adsorbed water, a basic raw material powder having spherical particles having an average particle diameter of about 10 to 20 µm is prepared by spray drying at a temperature of about 200 ° C. At this time, if the particle size of the basic raw material powder is about 10 to 20㎛, the fluidity of the powder is also improved, and when input from the molding process before the final product is obtained in the following process, the particle size of the original apatite hydroxide is easily about 50mm. It is broken and the molding density becomes high, and it shows good sintering characteristics even in the final process of sintering.

Subsequently, a certain amount is taken in the basic raw material powder having an average particle size of about 10 to 20 µm, prepared above, and calcined at a temperature range of about 700 to 1200 ° C. At this time, when the calcination treatment is performed, the fine particles react with each other and the grain growth occurs, and the specific surface area is about 5 to 15 m 2 / g after calcination, so most of the adsorbed water contained in the apatite hydroxide is lost. The activity is greatly reduced. At this time, if the calcination temperature is lowered to 700 ° C. or less, it takes a long time to release the adsorbed water, which is not economical, and the reaction between the particles does not occur sufficiently, thereby deteriorating the characteristic change of the sintered body. In addition, when the calcination temperature is increased to 1200 ° C. or more, there is a fear that aggregation phenomenon between particles occurs. 1, the plastic shrinkage rate of the basic raw material powder 1, the calcined powder 2 and the mixed powder 3 is shown. In this case, the basic raw material powder 1 undergoes rapid shrinkage from about 800 ° C and does not complete contraction even when it is about 1300 ° C. The calcined powder 2 has a smaller shrinkage rate than the basic raw material powder 1. Here, the mixed powder 3 shows their intermediate shrinkage rate.

Therefore, the basic raw material powder and the calcined powder prepared above were mixed at a weight ratio of about 10 to 50% by weight based on the calcined powder under the ball and mixed uniformly, and the mixed powder was mixed uniformly. It is placed in a mold and molded at a pressure of about 400 to 800 (kg / cm 2). The sectional view of the shaping | molding state of the calcined powder particle | grains 5 of the basic raw material powder particle 4 after shaping | molding is shown in FIG. 2A. Here, when the mixing ratio of the base material powder to the calcined powder is 10% by weight or less, it is difficult to mold because there is a large amount of the low activity calcined powder, and a small amount of the base raw material powder is not properly connected to the calcined powder. As a result, the strength of the sintering of the porous ceramics is lowered. On the other hand, when the mixing amount of the base raw material powder is 50% by weight or more, the porosity of the porous ceramics decreases due to the high raw material powder having high sinterability.

Subsequently, the molded article obtained above is sintered at a temperature of about 1050 to 1350 ° C. to prepare a calcium phosphate-based porous ceramic sintered body having an average pore diameter of about 0.01 to 10 μm and a porosity of about 5 to 40% by volume. The sectional view of the sintered state of the basic raw material powder particle 4 and the calcined powder particle 5 after sintering is shown in FIG. 2B.

The calcium phosphate-based porous ceramic sintered body obtained by the method of the present invention as described above is manufactured into granules having a granule size of about 0.3 to 2 mm. The electron microscope photograph taken in order to confirm the structure of the obtained porous ceramic sintered compact was shown in FIG.

Hereinafter, it demonstrates based on an Example as follows.

[Examples 1-3]

Phosphoric acid was reacted with a potassium hydroxide suspension to prepare an apatite hydroxide precipitate having a Ca / P molar ratio of 1.67. The precipitate was spray dried and granulated into particles having an average particle diameter of 15 µm to prepare a basic raw material powder. A part of the basic raw material powder was taken into a crucible and calcined at 1000 ° C. for 3 hours to form a calcined powder. The basic raw material powder and the calcined powder were put into a ball mill at the ratio shown in Table 1, and mixed for 30 minutes to uniformly mix. The mixed powder was placed in a metal mold, heated up to the temperature shown in Table 1, held for 3 hours, and then cooled by furnace to form a calcium phosphate porous ceramic sintered body. In order to make granules, the sieves were sieved and sifted to 0.3 ~ 2 mm in size.

The average pore diameter and porosity of the calcium phosphate porous ceramics sintered body were measured by mercury porosimetry and the results are shown in Table 1.

[Examples 4 to 6]

Phosphoric acid was reacted with a potassium hydroxide suspension to prepare an apatite hydroxide precipitate having a Ca / P molar ratio of 1.60. The precipitate was spray dried and granulated into particles having an average particle diameter of 12 µm to prepare a basic raw material powder. A part of the basic raw material powder was taken into a crucible and calcined at 900 ° C. for 3 hours to form a calcined powder. The basic raw material powder and the calcined powder were put into a ball mill at the ratio shown in Table 1, and mixed for 30 minutes to uniformly mix. The mixed powder was placed in a metal mold and molded at the pressures shown in Table 1. The molded body was placed in an electric furnace, heated to a temperature shown in Table 1 at a temperature increase rate of 5 ° C./min, held for 3 hours, and then cooled by furnace to form a calcium phosphate porous ceramic sintered body. In order to make granules, the sieves were sieved and sifted to 0.3 ~ 2 mm in size.

The average pore diameter and porosity of the calcium phosphate porous ceramics sintered body were measured by mercury porosimetry and the results are shown in Table 1.

TABLE 1

Average Pore Diameter and Porosity of Calcium Phosphate-Based Porous Ceramics Sintered Body According to Examples

Claims (2)

Apatite hydroxide having an average particle diameter of about 10 to 20 µm is used as the base raw material powder, and a certain amount of the powder is taken and calcined at about 700 to 1200 ° C. to produce a calcined powder. Calcium phosphate-based porous, characterized in that it has a pore diameter of about 0.01 to about 10㎛ prepared by adding, mixing and sintering at a rate of about 10 to 50% by weight, and having a porosity of about 5 to 40% by volume. Method for producing a ceramic sintered body. The method for producing a calcium phosphate porous ceramic sintered body according to claim 1, wherein the sintering temperature is in a range of 1050 to 1350 ° C.