Chemistry of inorganic compounds – Phosphorus or compound thereof – Oxygen containing
Reexamination Certificate
2000-11-27
2003-05-27
Langel, Wayne A. (Department: 1754)
Chemistry of inorganic compounds
Phosphorus or compound thereof
Oxygen containing
C423S309000, C423S311000
Reexamination Certificate
active
06569396
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method of manufacturing calcium phosphate powders such as &bgr;-tricalcium phosphate and hydroxy calcium phosphate or the like that are suitable for biomaterials, and more particularly relates to a method of manufacturing the calcium phosphate powders that are capable of easily manufacturing the calcium phosphate powders having an excellent characteristics through a simple manufacturing process, and capable of greatly reducing a manufacturing cost of the calcium phosphates.
BACKGROUND ART
Calcium phosphates typically represented by &bgr;-tricalcium phosphate [Ca
3
(PO
4
)
2
] and hydroxy calcium phosphate (hydroxy apatite) [Ca
10
(PO
4
)
6
(OH)
2
] are excellent in suitability to organism structure and have an affinity to organism body, so that calcium phosphates are valuable as bio-ceramic raw materials for constituting artificial bone, artificial tooth, artificial articulate or the like. In addition, calcium phosphates have been widely utilized as materials such as base material for tooth paste, additive for medical product, food additives, material for cosmetic chemist, separating/absorbing material for biopolymer and material for constituting humidity sensor or the like.
Conventionally, these calcium phosphate powders have been manufactured in accordance with the following methods such as wet-way (liquid phase) synthesizing method, dry-way (solid phase) synthesizing method, mechanochemical-reaction synthesizing method or the like. The wet-type synthesizing method is a synthesizing methodin which a calcium solution of calcium nitrate or the like is reacted with a phosphoric acid solution of ammonium hydrogen phosphate, or an amorphous calcium phosphate is produced from a reaction being taken place in heterogeneous system comprising calcium hydroxide and phosphoric acid, then the formed amorphous calcium phosphate is subjected to a calcining treatment thereby to produce &bgr;-tricalcium phosphate (&bgr;-TCP).
On the other hand, the dry-type synthesizing method is a method in which calcium carbonate is reacted with calcium pyrophosphate in a solid phase at a high temperature thereby to obtain calcium phosphate powder.
On the other hand, in these years, there has been also proposed a manufacturing method comprising simple manufacturing process and utilizing the mechanochemical reaction as a new method of synthesizing the calcium phosphate compound. For example, a publication of examined Japanese Patent Application No. HEI3-69844 and a publication of unexamined Japanese Patent Application No. HEI4-321508 disclose a method in which calcium carbonate powder and calcium hydrogenphosphate powder or dihydrate thereof are mixed to prepare a slurry of which molar ratio (Ca/P) of calcium to phosphor is controlled, then thus obtained slurry is milled by using a ball mill or a vibration mill or the like to cause reaction, thereafter, the reaction product is dried and heat-treated at a high temperature thereby to manufacture crystallized &bgr;-tricalcium phosphate (&bgr;-TCP).
Further, a publication of unexamined Japanese Patent Application No. HEI4-321508 discloses a method in which &bgr;-tricalcium phosphate is heated under a condition of existing water and pressingly treated thereby to manufacture hydroxy calcium phosphate (hydroxy apatite) powder. In this connection, in the conventional process of manufacturing the hydroxy calcium phosphate, a process directly using the mechanochemical reaction has not been adopted.
However, in case of the conventional wet-type synthesizing method, the synthesizing conditions such as the molar ratio of a raw material, treating speed, pH or the like are required to be strictly controlled. On the other hand, there is a difficulty in obtaining a product having a compositional high purity and uniformity. At any rate, for the purpose of obtaining a powder having a compositional high-purity and uniformity, there is posed a problem that the manufacturing cost would be greatly increased.
In contrast, in case of the conventional dry-type synthesizing method, the synthesized calcium phosphate powder has a coarse grain size, so that the powder cannot be directly used as a bio-ceramics raw material and a fine grinding or milling treatment is essentially required whereby there is posed a problem that the manufacturing process becomes complicate and troublesome.
On the other hand, in case of the conventional synthesizing method utilizing the mechanochemical react ion, a long-term grinding process for 1 day to 50 hours is essentially required for advancing the reaction, thereby to cause a problem that the production cost is greatly increased. In addition, in order to smoothly advance the reaction, a solid content of the slurry is required to be set to a lower level. Therefore, there are posed various problems such that an amount of heat energy to be put into the subsequent drying process remarkably increases, a drying operation is required to perform for a long time. In addition, for the purpose of pulverizing or grinding the coarsely aggregated bodies caused by the drying operation, an additional grinding process is essentially required, so that there is posed a fatal problem such that a running cost for the manufacturing facilities and the production cost are greatly increased.
The present invention had been achieved to solve the aforementioned problems and an object of the present invention is to provide a method of manufacturing calcium phosphate powder, the method being capable of easily manufacturing fine calcium phosphate powder having excellent characteristics by a simple manufacturing process and capable of greatly reducing the production cost of the powder.
DISCLOSURE OF THE INVENTION
In order to achieve the aforementioned object, the inventors of the present invention had prepared calcium phosphate powders under various conditions by using various material powders, reacting synthesizing methods and pulverizing devices (grinding machines). Then, through many experiments, the inventors had comparatively reviewed the influences of the differences in the manufacturing conditions onto characteristics and manufacturing cost of calcium phosphate powder as a product.
As a result, the inventors had found and obtained the following knowledge. That is, when calcium hydroxide powder as a raw material is used in place of the conventional calcium carbonate, then the calcium hydroxide powder is mixed to calcium hydrogen phosphate powder thereby to prepare a mixed material, then the mixed material is further mixed and milled to take place a mechanochemical reaction. Thereafter, when the reaction product is heat-treated, there can be obtained knowledge that fine particles of calcium phosphate compound having a high crystallinity and high homogeneity can be effectively manufactured in a short time.
In particular, when a multi-ring media type ultrafine mill comprising a number of ring-shaped milling media is used as a mixing and milling device for advancing a mechanochemical reaction by conducting the mixing and the milling of the mixed material, there could be also obtained the findings such that a reaction activity of the mixed material was increased, and it became possible to rapidly advance the above mechanochemical reaction whereby a production efficiency of the calcium phosphate compound could be remarkably increased.
Furthermore, in the conventional various synthesizing methods conducted in a wet, the solid component content (viscosity) of the mixed material slurry required to be suppressed to a lower level, and the mixed material slurry is required to be mixed and pulverized for a long time. In contrast, when the above ultrafine mill is used, even if the slurry has a high solid content and a high viscosity, there could be also obtained a finding that it becomes possible to mix and pulverize the slurry in a short time whereby the production efficiency of the calcium phosphate compound could be remarkably increased.
The present invention had been achieved on the basis of the above findings. Namely
Isobe Tetsuhiko
Kanayama Manabu
Senna Mamoru
Yanagi Shouhan
Langel Wayne A.
Nara Machinery Co., Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
LandOfFree
Method for producing calcium phosphate powder does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing calcium phosphate powder, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing calcium phosphate powder will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3082100