Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Patent
1998-01-05
2000-03-07
Le, Hoa T.
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
106122, 106672, 106682, 106816, B32B 516, C04B 1608
Patent
active
06033780&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to fine particles of petaloid porous hydroxyapatite having a specific particle diameter, specific dispersibility, specific diameter of micropore and specific percentage of voids, an atomic ratio of Ca/P of 1.62-1.72 and the chemical formula Ca.sub.5 (PO.sub.4).sub.3 (OH), and a method for manufacturing the same. Further, the method of the present invention provides a method for manufacturing the novel fine particles of petaloid porous hydroxyapatite of the present invention with low cost and industrially with ease.
The novel fine particles of petaloid porous hydroxyapatite of the present invention are useful as carriers for catalysts, pharmaceuticals., agricultural medicines, microbials, biologicals and peroxides, plant growth agents, absorbents of olefins, absorbents of ultraviolet, adsorbents, sustained-release materials, liquids-absorbing agents, raw materials for ceramics, many kinds of carriers, filtering agents, filtering aids, molding aids, growth for microbials, biological materials, drying agents, carriers for fragrants and so on, or raw materials thereof, fillers for plastics, rubbers, paints, ink, sealing materials and a paper manufacture, and anti-blocking agents for fibers and films. Furthermore, a new use of the particles can be developed by combining the above mentioned many kinds of use.
BACKGROUND ART
It is well known that porous hydroxyapatite exists in a human body. For example, the porous hydroxyapatite is a component of bone and teeth. Therefore, recently, the porous hydroxyapatite is focused as a raw material for bioceramics and many studies have been performed on the porous hydroxyapatite. On the other hand, fine powders of hydroxyapatite which are not porous are industrially manufactured and sold as raw materials for the porous hydroxyapatite, food additives (as calcium triphosphate), stabilizers for polymerization, catalysts and so on.
As known porous hydroxyapatites, (1)spherical apatite, (2)porous apatite, (3)hollow calcium phosphate, (4)granules of calcium phosphate compound, (5)porous bone supplement of calcium phosphate, (6)porous spherical calcium phosphate and so on are reported. The followings are outlines of the above known porous hydroxyapatites.
(1) As the spherical apatite, Japanese laid-open patent publication No.3-16906 entitled "Spherical apatite and manufacturing method thereof and porous structure molded articles" can be exemplified.
This prior art is directed to a spherical apatite, which is comprised of calcium phosphate having its composition of Ca/P molar ratio of 1.4-1.8 and a specific gravity of 3.00-3.17. The spherical apatite has features of a true spherical structure, and a minute and high mechanical strength. However, since the spherical apatite is minute, it has a defect that a percentage of voids is extremely low.
Manufacturing method of the spherical apatite is that a slurry comprising hydroxyapatite as its main component is dried and powdered to prepare aggregates of primary apatite particles, preferably, spray dried to form spherical particles, and then the prepared aggregates of primary apatite particles are fused in a flame of 1500.degree. C. or more so as to obtain the spherical apatite.
The prior art discloses that an apatite of porous structure can be obtained by mixing an adhesive to the aforementioned spherical apatite, pressure molding, and then calcinating in the flame of 1500.degree. C. or more, however, the percentage of voids of the thus obtained porous structure in Examples is 28%, which is a very low value, and therefore, it can not be said that the obtained porous structure has high percentage of voids.
(2) As the porous apatite, Japanese patent publication No.2-14311 entitled "A method for manufacturing a porous apatite" can be exemplified.
Claim 1 of the patent publication describes as follows: "A method for manufacturing a porous apatite which comprises blending calcium carbonate powders to calcium hydrogenphosphate.2H.sub.2 O or an anhydride thereof so that the Ca/P molar ratio beco
Hanazaki Minoru
Nishioka Hidehiko
Takiyama Shigeo
Le Hoa T.
Maruo Calcium Company Limited
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