Patent EP0026090A2 successfully refreshed from Google Patents.
EP0026090A2
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EP
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Process for preparing hydroxyapatite, and filter cake, ceramic material and implant material comprising hydroxyapatite
Assignee: Kureha Corp
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Filing: 1980-09-18
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Granted: —
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Expires: 2000-09-18
Abstract
Abstract Hydroxyapatite is an inorganic component of skeletal tissues, such as bones and teeth. It is known to synthesise hydroxyapatite for use as implant materials, such as artificial bones, by the reaction of calcium hydroxide with phosphoric acid. Known synthetic hydroxyapatite is, however, not sufficiently like the naturally occurring material to be entirely satisfactory for use in providing implant materials. <??>The invention provides a process for synthesising hydroxyapatite which comprises thermally decomposing calcium carbonate, cooling the resultant calcium oxide, slaking the cooled calcium oxide, and reacting the resulting calcium hydroxide with phosphoric acid. A filter cake of the synthetic hydroxyapatite thus produced is porous and contains crystals which can readily be sintered to provide a thermally stable ceramic material which is colorless or semi-transparent and useful in providing implant materials compatible with a living body.
Inventors
- 👤 Hirosi Nagai
- 👤 Yasushi No. 404 Haitsu-Takada-No-Baba Nishimura
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 03:40
CPC Classifications
A; A61; A61L; A61L27/00; A61L27/02; A61L27/12; A61L27/40; A61L27/44; A61L27/46; C; C01; C01B; C01B25/00; C01B25/16; C01B25/26; C01B25/32; C01B25/322; C04; C04B; C04B35/00; C04B35/01; C04B35/447; A61F; A61F2310/00; A61F2310/00005; A61F2310/00179; A61F2310/00293; Y; Y10; Y10S; Y10S623/00; Y10S623/92
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
96 words
A process for preparing hydroxyapatite by the reaction of calcium hydroxide with phosphoric acid, characterised by (a) converting calcium carbonate powder into calcium oxide by thermal decomposition in an inert atmosphere at a temperature of 800 to 1300°C for 0:5 to 10 hours; (b) cooling the calcium oxide to a temperature lower than 500°C in the inert atmosphere; (c) slaking the cooled calcium oxide with water while agitating thereby to obtain calcium hydroxide; and (d) reacting the calcium hydroxide with an aqueous solution of phosphoric acid while agitating in an inert atmosphere thereby to obtain hydroxyapatite.
Claim 2
Dependent Claim
96 words
A process for preparing hydroxyapatite by the reaction of calcium hydroxide with phosphoric acid, characterised by (a) converting calcium carbonate powder into calcium oxide by thermal decomposition in an inert atmosphere at a temperature of 800 to 1300°C for 0:5 to 10 hours; (b) cooling the calcium oxide to a temperature lower than 500°C in the inert atmosphere; (c) slaking the cooled calcium oxide with water while agitating thereby to obtain calcium hydroxide; and (d) reacting the calcium hydroxide with an aqueous solution of phosphoric acid while agitating in an inert atmosphere thereby to obtain hydroxyapatite.
Claim 3
Dependent Claim
27 words
A process according to claim 1, characterised in that an aqueous suspension of calcium hydroxide is reacted with the aqueous solution of phosphoric acid in step (d).
Claim 4
Dependent Claim
33 words
A process according to claim 1 or 2, characterised in that the calcium hydroxide is reacted with the aqueous solution of phosphoric acid in stop (d) at a temperature of 0 to 50°C.
Claim 5
Dependent Claim
32 words
A process according to claim 1, 2 or 3 characterised in that the reaction product from step (d) is filtered and dried to a water content of 2% by weight or less.
Claim 6
Dependent Claim
85 words
A filtered, dried cake of synthetic hydroxyapatite characterised by having a three-dimensional porous structure with an average pore radius of 50 to 150 Å and a pore volume of 0.2 to 0.8 cm 3 /g, said cake comprising crystalline hydroxyapatite having an atomic ratio of calcium to 'phosphorus of 1.67 : 1 to 1.69 : 1 in which the crystals have a length of 150 to 1200 A, a width of 50 to 400 A, and a length to width ratio of 3:1 to 10:1.
Claim 7
Dependent Claim
85 words
A filtered, dried cake of synthetic hydroxyapatite characterised by having a three-dimensional porous structure with an average pore radius of 50 to 150 Å and a pore volume of 0.2 to 0.8 cm 3 /g, said cake comprising crystalline hydroxyapatite having an atomic ratio of calcium to 'phosphorus of 1.67 : 1 to 1.69 : 1 in which the crystals have a length of 150 to 1200 A, a width of 50 to 400 A, and a length to width ratio of 3:1 to 10:1.
Claim 8
Dependent Claim
71 words
A ceramic material comprising synthetic hydroxyapatite and having an atomic ratio of calcium to phosphorus of 1.67 : 1 to 1.69 : 1 characterised by average crystal size of 4 to 20 P, a density of 3.14 to 3.16 g/cm 3 and a thermal stability such that substantially no whitlockite is formed upon heating for at least one hour at a temperature of 1350°C, said ceramic material being colourless or semi-transparent.
Claim 9
Dependent Claim
71 words
A ceramic material comprising synthetic hydroxyapatite and having an atomic ratio of calcium to phosphorus of 1.67 : 1 to 1.69 : 1 characterised by average crystal size of 4 to 20 P, a density of 3.14 to 3.16 g/cm 3 and a thermal stability such that substantially no whitlockite is formed upon heating for at least one hour at a temperature of 1350°C, said ceramic material being colourless or semi-transparent.
Claim 10
Dependent Claim
23 words
A ceramic material according to claim 6 characterised by comprising the sintered product of a dried, filtered cake as claimed in claim 5.
Claim 11
Dependent Claim
28 words
An implant material comprising a ceramic hydroxyapatite material and a biologically acceptable bonding material characterised in that the ceramic material is as claimed in claim 6 or 7.
Claim 12
Dependent Claim
26 words
An implant material according to claim 8, characterised in that the ceramic material forms from 5 to 70% of the surface area of the implant material.
Claim 13
Dependent Claim
49 words
An implant material according to claim 8 or 9, characterised in that the bonding material comprises at least one of polycondensates of bisphenol A and glycidyl methacrylate, methyl methacrylate polymers, 2-hydroxyethyl methacrylate polymers, triethyleneglycol dimethacrylate polymers, ethylene polymers, sulfone polymers, polyamides, polyesters, tetrafluoroethylene polymers, vinylidene fluoride polymers and polycarbonates.
References Cited (Backward Citations)
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