JP3215892B2 - Method for producing hydroxyapatite whiskers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing hydroxyapatite whiskers. In the present specification, “%”
And "parts" mean "% by weight" and "parts by weight", respectively.

[0002]

2. Description of the Related Art Hydroxyapatite is being developed for practical use as a biocompatible material in the medical field such as artificial bones, artificial teeth, and adsorbents for separating blood components. It is also expected to be useful as a reinforcing material such as ceramics and plastics. Conventional methods for producing hydroxyapatite include (1) a method in which a water-soluble calcium salt is reacted with a water-soluble phosphate, (2) a method in which quicklime or slaked lime is added to a slurry of calcium hydrogenphosphate to cause a reaction, 3) A method of adding quicklime to a slurry of tricalcium phosphate and hydrolyzing with an aqueous alkaline solution is known. The properties of the hydroxyapatite obtained by these known methods are mainly simple granular powders or columnar powders, and whisker-like ones may be mixed. However, even when whisker-like materials are mixed, the fiber length is short and an agglomerate is formed, so that it cannot exhibit sufficient properties as a medical material, a reinforcing material for a composite material, or the like.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydroxyapatite whisker having excellent properties as a medical material, a reinforcing material for a composite material and the like.

[0004]

Means for Solving the Problems The present inventor has conducted intensive studies in view of the above-mentioned state of the art, and has found that hydroxyapatite, tricalcium phosphate or dicalcium phosphate can be used in the presence of an alkali metal salt. It has been found that when calcined underneath, hydroxyapatite substantially consisting of whiskers is obtained.

That is, the present invention provides a method for producing a hydroxyapatite whisker as follows: "In the presence of an alkali metal salt, at least one of hydroxyapatite, calcium phosphate and dicalcium phosphate is used.
A method for producing hydroxyapatite whiskers, characterized by firing at 00 to 1200 ° C. "

[0006] The material used as a raw material in the present invention is at least one of hydroxyapatite, tricalcium phosphate and dicalcium phosphate. According to a known method, these calcium phosphate-based raw materials include a calcium source such as calcium oxide, calcium hydroxide, calcium carbonate, calcium chloride, and calcium nitrate, and a phosphorus source such as phosphoric acid, sodium phosphate, potassium phosphate, and ammonium phosphate. By reacting with an acid source under wet conditions,
Each of them can be obtained alone or in the form of a mixture of two or more. The properties of the raw material include granular powder, columnar powder, and those mixed with a small amount of whiskers, and any of them may be used. The particle size of the raw material is not particularly limited, but is preferably about 10 μm or less. By setting the particle size of the raw material to 10 μm or less, compression molding for forming whiskers described later is facilitated, and the whisker formation rate is also improved.

In the present invention, it is essential to use at least one alkali metal salt as a catalyst with the above raw materials. Examples of such an alkali metal salt include sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium borate, potassium borate and the like. The catalyst may be added to the raw material by immersing or spraying the raw material powder in a solution of the catalyst component and then drying, or by mixing the raw material powder and the catalyst component powder (preferably about 10 μm or less).
Or a catalyst component is previously allowed to coexist when the raw material is produced by the above-mentioned wet method. The blending amount of the catalyst with respect to the raw material is about 10 to 400 parts (as solid content) for the former 100 parts. If the amount of the catalyst is less than 10 parts with respect to 100 parts of the raw material, the transfer rate to whiskers is low, whereas 4%.
If it exceeds 00 parts, the fiber diameter becomes too thick,
The fired product may become a glassy molten material.

In the present invention, a mixture of the above-mentioned raw material and catalyst is formed and fired at a temperature of 800 to 1200 ° C. If the sintering temperature is lower than 800 ° C., whisker growth is not sufficiently performed, while if it exceeds 1200 ° C., a part of the raw material may be decomposed. The firing time varies depending on the amount of the catalyst used, the size of the molded body, and the like. However, in consideration of sufficient growth of whiskers, at least about 1 hour is usually necessary, and about 8 hours is the upper limit. The firing atmosphere is not particularly limited, but firing in the air is practically advantageous.

[0009] The fired compact is allowed to cool and then crushed in warm water to remove unreacted raw materials and catalyst, and then washed with water. As a result, a desired hydroxyapatite whisker is obtained.

The resulting hydroxyapatite whiskers are:
Usually, the length is about 5 to 150 μm and the diameter is about 0.2 to 5 μm.

[0011]

The hydroxyapatite whiskers obtained by the method of the present invention can be used as artificial bones, artificial teeth,
It is useful as a material for medical materials such as an adsorbent for separating blood components. The hydroxyapatite whiskers obtained by the method of the present invention are also useful as reinforcing materials for ceramics, plastics, etc., and significantly improve the strength, elastic modulus, etc. of the resulting composite material.

Examples and comparative examples are shown below to further clarify the features of the present invention.

Examples 1 and 2 1470 g of calcium chloride dihydrate was dissolved in water 51, and an aqueous solution 31 containing 800 g of sodium hydroxide was added thereto, and 690 g of an 85% phosphoric acid solution was further added. The mixture was heated to 90 to 100 ° C., kept for 4 hours, and reacted. After completion of the reaction, the product was washed with water and dried to obtain 760 g of hydroxyapatite. The obtained hydroxyapatite was a white columnar crystalline powder, and the molar ratio of calcium to phosphorus was 1: 1.64. Next, a catalyst was added to the hydroxyapatite obtained above in the ratio shown in Table 1 below,
After being molded under pressure, baked, and allowed to cool, crushed in warm water,
Hydroxyapatite whiskers were obtained. The properties of the obtained hydroxyapatite whiskers are shown in Table 1.

Example 3 1328 g of calcium chloride dihydrate was dissolved in 5 l of water, 4 l of an aqueous solution containing 792 g of diammonium phosphate was mixed with the solution, and the pH of the mixture was adjusted to about 7 with 28% aqueous ammonia. And reacted for 4 hours. After the completion of the reaction, the product was washed with water and dried to obtain 700 g of tricalcium phosphate. The obtained tricalcium phosphate is a white amorphous powder, and the molar ratio of calcium to phosphorus is 1: 1.52
Met. Next, a catalyst was added to the hydroxyapatite obtained above at the ratio shown in Table 1 below, molded under pressure, calcined, allowed to cool, and then crushed in warm water to obtain a hydroxyapatite.
Got whiskers. The properties of the obtained hydroxyapatite whiskers are shown in Table 1.

Example 4 Tricalcium phosphate obtained in the same manner as in Example 3 was calcined in air at 800 ° C. for 3 hours to obtain β-tricalcium phosphate. Next, a catalyst was added to the above-obtained β-tricalcium phosphate at a ratio shown in Table 1 below, molded under pressure, calcined, allowed to cool, and then crushed in warm water to form hydroxyapatite.・ I got a whisker. The properties of the obtained hydroxyapatite whiskers are shown in Table 1.

Examples 5 to 6 518 g of calcium hydroxide was dispersed in 10 l of water, 807 g of an 85% phosphoric acid solution was added thereto, and the mixture was kept for 4 hours to react. After the completion of the reaction, the product was washed with water and dried to obtain 1000 g of dicalcium phosphate. The obtained dicalcium phosphate was a scaly, glossy powder, and the molar ratio of calcium to phosphorus was 1: 1.1. Next, a catalyst was added to the dicalcium phosphate obtained above in the ratio shown in Table 1 below, molded under pressure, and calcined.
After allowing to cool, it was crushed in warm water to obtain hydroxyapatite whiskers. The properties of the obtained hydroxyapatite whiskers are shown in Table 1.

Comparative Example 1 Hydroxyapatite produced in the same manner as in Example 1 was directly molded without adding a catalyst, calcined, allowed to cool, and then crushed in warm water, but no whisker was formed. Was.

Comparative Example 2 Tricalcium phosphate produced in the same manner as in Example 4 was directly molded without adding a catalyst, calcined, allowed to cool, and then crushed in warm water, but no whisker was formed. Was.

Comparative Example 3 Dicalcium phosphate produced in the same manner as in Example 5 was directly molded without adding a catalyst, calcined, allowed to cool, and then crushed in warm water, but no whisker was formed. Was.

[0020] Table 1 Example Raw material catalysts Firing Conditions Typical Properties 1 hydroxyl AP sulfate K 1200 ° C. × 1 hour in length 5 30 .mu.m 5 parts 20 parts diameter 0.2 to 0.5 [mu] m 2 hydroxyl AP borate K 1000 ° C. × 2 hours Length 10-100 μm 10 parts 20 parts Diameter 0.2-0.5 μm 3 Tri-phosphate Ca-Ca-borate Na 950 ° C. × 3 hours Length 10-50 μm 5 parts 15 parts Diameter 1.0-5.0 μm 4 Phosphoric acid Tri-Ca Sulfuric acid K 1100 ° C × 2 hours Length 10-50 μm 10 parts 15 parts Diameter 1.0-5.0 μm 5 Diphosphate phosphate Na 900 ° C. × 2 hours Length 5-50 μm 5 parts 20 parts Diameter 1.0-5.0 μm 6 Dicalcium phosphate Chloride K 1000 ° C × 6 hours Length 5-50 μm 10 parts 5 parts Diameter 1.0-5.0 μm Comparative Example 1 Hydroxide AP-1200 ° C × 1 hour No whisker formed 2 Triphosphate-1100 ° C × 2 Time No whiskers formed 3 Ca-diphosphate-900 ° C x 6 hours No whiskers Note: Hydroxy AP: Hydroxyapatite Phosphoric acid Ca: tricalcium phosphate (However, the product of Example 3 is a dried product; the products of Example 4 and Comparative Example 2 are calcined products) DiCa: dicalcium phosphate Sulfate K: potassium sulfate Borate K: boric acid Potassium Na borate ... Sodium borate Chloride K ... Potassium chloride Na ... Sodium chloride

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ identification code FI // A61K 6/033 A61K 6/033 C04B 35/80 C04B 35/80 A (58) Fields surveyed (Int.Cl. ⁷ , DB name) C01B 25/32 C04B 35/80 CA (STN)

Claims (1)

(57) [Claims] 1. A method for producing hydroxyapatite whiskers, wherein at least one of hydroxyapatite, calcium phosphate and dicalcium phosphate is calcined at 800 to 1200 ° C. in the presence of an alkali metal salt.