US5427754A
Expired / Lapsed
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Method for production of platelike hydroxyapatite
Assignee: National Institute of Advanced Industrial Science and Technology
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Filing: 1993-12-28
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Granted: 1995-06-27
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Expires: 2013-12-28
Abstract
Abstract A platelike hydroxyapatite is produced by preparing from a phosphate and a calcium salt an aqueous slurry of amorphous calcium phosphate having an atomic ratio of calcium atoms to phosphorus atoms in the range of 1.3:1 to 2.0:1, adding to the aqueous slurry not less than 10% by weight of alcohol based on the amount of the aqueous slurry, and subjecting the resultant mixture to a hydrothermal treatment.
Inventors
- 👤 Fukue Nagata
- 👤 Yoshiyuki Yokogawa
- 👤 Motohiro Toriyama
- 👤 Yukari Kawamoto
- 👤 Takahiro Suzuki
- 👤 Kaori Nishizawa
- 👤 Hajime Nagae
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:22
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/16; C01B25/26; C01B25/32; C01B25/327
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
116 words
A method for the production of a platelike hexagonal hydroxyapatite grown along its a and b axes, which comprises the steps of: mixing a phosphate, a calcium salt and water so as to obtain an atomic ratio of calcium atoms to phosphorus atoms in the ratio of 1.3:1 to 2.0:1, thereby forming an aqueous slurry of amorphous calcium phosphate; adding to said aqueous slurry at least 10% by weight of alcohol based on an amount of said slurry to obtain a mixture; treating said mixture in a pressure vessel at a pressure of 1-200 kgf/cm 2 by application of heat under saturated vapor pressure to obtain said hydroxyapatite; and then subjecting said hydroxyapatite to solid-liquid separation.
Claim 2
Independent Claim
116 words
A method for the production of a platelike hexagonal hydroxyapatite grown along its a and b axes, which comprises the steps of: mixing a phosphate, a calcium salt and water so as to obtain an atomic ratio of calcium atoms to phosphorus atoms in the ratio of 1.3:1 to 2.0:1, thereby forming an aqueous slurry of amorphous calcium phosphate; adding to said aqueous slurry at least 10% by weight of alcohol based on an amount of said slurry to obtain a mixture; treating said mixture in a pressure vessel at a pressure of 1-200 kgf/cm 2 by application of heat under saturated vapor pressure to obtain said hydroxyapatite; and then subjecting said hydroxyapatite to solid-liquid separation.
Claim 3
Dependent Claim
30 words
A method according to claim 1, wherein said phosphate is at least one member selected from the group consisting of calcium hydrogen phosphate, calcium hydrogen phosphate dihydrate, and ammonium phosphate.
Claim 4
Dependent Claim
13 words
A method according to claim 1, wherein said calcium salt is calcium carbonate.
Claim 5
Dependent Claim
40 words
A method according to claim 1, wherein said phosphate and said calcium salt are mixed so that the atomic ratio of calcium atoms to phosphorus atoms in said phosphate and calcium salt is in the range of 1.5:1 to 1.8:1.
Claim 6
Dependent Claim
21 words
A method according to claim 1, wherein the temperature of said treatment is in the range of 120° to 200° C.
Claim 7
Dependent Claim
28 words
A method according to claim 1, wherein the concentration of said amorphous calcium phosphate in said aqueous slurry is in the range of 1 to 10% by weight.
Claim 8
Dependent Claim
25 words
A method according to claim 1, wherein said alcohol is at least one member selected from the group consisting of methanol, ethanol, 1-propanol and glycerol.
Claim 9
Dependent Claim
20 words
A method according to claim 5, wherein the pressure of said treating step is at least 10 kgf/cm 2 .
Claim 10
Dependent Claim
18 words
A method according to claim 8, wherein the pressure of said treating step is 10-22 kgf/cm 2 .
Claim 11
Dependent Claim
23 words
A method according to claim 7, wherein said alcohol is at least one member selected from the group consisting of methanol and ethanol.
Claim 12
Dependent Claim
22 words
A method according to claim 1, wherein not less than 30% by weight of said alcohol is added to said aqueous slurry.
Claim 13
Dependent Claim
15 words
A method according to claim 1, wherein said heat is applied for approximately 2-20 hours.
Claim 14
Dependent Claim
16 words
A method as claimed in claim 12, wherein said heat is applied for approximately 5-20 hours.
References Cited (Backward Citations)
US4481175A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-06-26 | 1998-12-26 | 1999-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-06-26 | 2002-12-26 | 2003-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-06-26 | 2006-12-26 | 2007-06-27 | $7700.00 | Window Closed / Lapsed |