Calcium phosphate porous sintered body and production thereof

• US 6,340,648 B1
• Filed: 04/13/2000
• Issued: 01/22/2002
• Est. Priority Date: 04/13/1999
• Status: Expired due to Fees

• Current Assignee: National Institute For Research In Inorganic Materials-Science and Technology Agency, Covalent Materials Corporation (Trelleborg AB)
• Original Assignee: Toshiba Ceramics Co Ltd (Momentive Performance Materials Incorporated), National Institute For Research In Inorganic Materials-Science and Technology Agency, Toshiba Denko Co., Ltd. (Toshiba Corporation)
• Inventors: Kinoshita, Masami, Suetsugu, Yasushi, Minowa, Nobuaki, Yamazaki, Hiraku, Hojo, Akimichi, Tanaka, Junzo, Kikuchi, Masanori, Uemoto, Hideo, Imura, Kohichi
• Primary Examiner(s): KOSLOW, CAROL M
• Application Number:
  US09/548,742
• Time in Patent Office: 649 Days
• Field of Search: 501/1, 501/123, 501/84, 501/80, 106/35, 623/16.11, 623/23.56, 623/23.61
• US Class Current: 501/80
• CPC Class Codes: A61L 27/12 Phosphorus-containing materials, e.g. apatite
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: C04B 2111/00612 as one or more layers of a layered structure
• CPC Class Codes: C04B 35/447 based on phosphates , e.g. hydroxyapatite
• CPC Class Codes: C04B 38/0054 the pores being microsized or nanosized
• CPC Class Codes: C04B 38/0074 expressed as porosity percentage
• CPC Class Codes: C04B 38/062 the burned-out substance being formed in situ, e.g. by polymerisation of a prepolymer composition containing ceramic powder
• CPC Class Codes: C04B 41/5353 Wet etching, e.g. with etchants dissolved in organic solvents

Abstract

A calcium phosphate porous sintered body which comprises spherical pores communicating with one another substantially throughout the body with a porosity of 55% or more and 90% or less, and has an average diameter of the inter-pore communicating parts of 50 μm or more, a pore diameter of 150 μm or more, and a three-point bending strength of 5 MPa or more, and a method for producing the same.

Claims

1. A calcium phosphate porous sintered body having a porous structure which comprises roughly spherical pores communicating with one another substantially throughout the body with a porosity of 55% or more and 90% or less, and has an average diameter of the inter-pore communicating parts of 50 μ

m or more in average, a pore diameter of 150 μ

m or more, and a three-point bending strength of 5 MPa or more.

2. A calcium phosphate porous sintered body according to claim 1 wherein the skeleton part of the calcium phosphate porous sintered body consists of a substantially densed calcium phosphate sintered body, its surface part has fine irregularities or a layer consisting of the calcium phosphate porous sintered body, and the specific surface area of the calcium phosphate porous sintered body is 0.1 m²/g or more.

3. A calcium phosphate porous sintered body according to claim 1 wherein the calcium phosphate porous sintered body is mainly composed of at least one of compounds of the calcium phosphate group consisting of CaHPO₁, Ca₃(PO₄)₂, Ca₅(PO₄)₃OH, Ca₄O(PO₄)₂, Ca₁₀(PO₄)₆(OH)₂, CaP₄O₁₁, Ca(PO₃)₂, Ca₂P₂O₇, Ca(H₂PO₄)₂, and Ca(H₂PO₄)₂.H₂O.

4. A calcium phosphate porous sintered body according to claim 3 wherein the component Ca is partially substituted by at least one selected from Sr, Ba, Mg, Fe, Al, Y, La, Na, K, Ag, Pd, Zn, Pb, Cd, H and other rare earth metals, the component (PO₄) is partially substituted by at least one selected from VO₄, BO₃, SO₄, CO₃, and SiO₄, and the component (OH) is partially substituted by at least one selected from F, Cl, O, CO₃, I and Br.

5. A calcium phosphate porous sintered body according to claim 1 wherein the calcium phosphate porous sintered body consists of a calcium phosphate which is any of crystalline, homogeneous solid solution, substitutional solid solution or interstitial solid solution, and can include a non-stoichiometric defect.

6. A method for producing a calcium phosphate porous sintered body which comprises steps of preparing a slurry by dispersing and/or dissolving calcium phosphate powder and an organic polymer material which is hardenable by cross-linking polymerization in a solvent;

adding a foaming agent to the slurry and foaming it to a prescribed volume by stirring and/or gas introduction to lay the slurry in a foamed state;

adding a cross-linking agent and/or a cross-linking initiator to the foamed slurry followed by mixing, introducing the resulting mixture to a die, and hardening it by cross-linking polymerization to form a compact; and

drying the compact followed by sintering.

7. A method for producing a calcium phosphate porous sintered body according to claim 6 wherein the organic material hardenable by cross-linking polymerization is a linear, branch or block polymer containing amino group of polyacrylamide, polyethylene imine or polypropylene imine, and the cross-linking agent is an epoxidized compound having two or more epoxy groups of sorbitol polyglycydyl ether, polyglycerol polyglycydyl ether, pentaerythritol polyglycydyl ether, diglycerol polyglycydyl ether, glycerol polyglycydyl ether or polymethylolpropane polyglycydyl ether.

8. A method for producing a calcium phosphate porous sintered body according to claim 6 wherein the surface of the skeleton part of the calcium phosphate porous sintered body is etched with an acid to provide fine irregularities on the surface of the skeleton part.

9. A method for producing a calcium phosphate porous sintered body according to claim 8 wherein the etching step with the acid consists of the step of carrying the acid into the pores of the calcium phosphate porous sintered body set within an acid passage so as to block the passage.

10. The method for producing a calcium phosphate porous sintered body according to claim 6 further comprising adhering a slurry containing a calcium phosphate powder to the surface of the skeleton part consisting of a substantially densed calcium phosphate sintered body of the calcium phosphate porous sintered body, drying and sintering to provide a layer of the substantially densed calcium phosphate sintered body on the surface of the skeleton part of the calcium phosphate porous sintered body.

11. The method for producing a calcium phosphate porous sintered body according to claim 6 further comprising adhering a slurry containing a calcium phosphate powder to the surface of the skeleton part consisting of a substantially densed calcium phosphate sintered body of the calcium phosphate porous sintered body, drying and sintering to provide a layer of the calcium phosphate sintered body on the surface of the skeleton part of the calcium phosphate porous sintered body.

12. A method for producing a calcium phosphate porous sintered body according to claim 6 wherein the calcium phosphate powder is mainly composed of at least one of compounds of the calcium phosphate group consisting of CaHPO₄, Ca₃(PO₄)₂, Ca₅(PO₄)₃OH, Ca₄O(PO₄)₂, Ca₁₀(PO₄)₆(OH)₂, CaP₄O₁₁, Ca(PO₃)₂, Ca(H₂PO₄)₂, Ca₂P₂O₇, and Ca(H₂PO₄)₂.H₂O.

13. A method for producing a calcium phosphate porous sintered body according to claim 12 wherein the component Ca is partially substituted by at least one selected from Sr, Ba, Mg, Fe, Al, Y, La, Na, K, Ag, Pd, Zn, Pb, Cd, H and other rare earth metals, the component (PO₄) is partially substituted by at least one selected from VO₄, BO₃, SO₄, CO₃, and SiO₄, and the component (OH) is partially substituted by at least one selected from F, Cl, O, CO₃, I, and Br.

14. A method for producing a calcium phosphate porous sintered body according to claim 6 wherein the calcium phosphate powder consists of a calcium phosphate, which is any of crystalline, homogeneous solid solution, substitutional solid solution and interstitial solid solution, and can include a non-stoichiometric defect.