# US 4,376,168 A · Phosphate of calcium ceramics

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- Number: US 4,376,168 A
- Document ID: US4376168A
- Status: Granted
- Kind: A
- Application number: 06/256,007
- Filed: 1981-04-21
- Granted: 1983-03-08
- Earliest claimed: 1978-10-19
- Assignees: NGK Spark Plugs Co., Ltd.
- Inventors: Akio Takami; Kazuo Kondo
- Web page: https://patentgrep.com/patent/US4376168A

## CPC

- A61L 27/12: Phosphorus-containing materials, e.g. apatite
- C04B 35/447: based on phosphates {, e.g. hydroxyapatite}
- A61F 2310/00293: containing a phosphorus-containing compound, e.g. apatite
- A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K)
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)

## Abstract

A strong and biocompatible sintered phosphate of calcium ceramics are obtained by sintering a powdery material substantially consisting of phosphate of calcium having a Ca/P ratio of 1.4-1.75, e.g. apatite group and/or tricalcium phosphate, and not exceeding 15% by weight of CaO-P.sub.2 O.sub.5 frit having a Ca/P ratio of 0.2-0.75. Y.sub.2 O.sub.3 incorporation therein improves the bending strength of the ceramics. Furthermore, a P.sub.2 O.sub.5 -metal oxide frit wherein metal oxide being one or more selected from BaO, CaO, MgO, ZnO, NaO and K.sub.2 O provides a more improved bending strength. The Y.sub.2 O.sub.3 incorporation herein still improves the strength of the sintered product.

## Claims

### Claim 1

Phosphate of calcium ceramics obtained by sintering a composition essentially consisting of 0.5-15% by weight of P.sub.2 O.sub.5 -metal oxide frit and the balance of a powdery material substantially consisting of phosphate of calcium having a Ca/P atomic ratio of 1.4-1.75, said P.sub.2 O.sub.5 -metal oxide frit essentially consisting, in mol% calculated for the frit, of 40-75% of P.sub.2 O.sub.5 and 20-55% of one or more metal oxide selected from the group consisting of BaO, CaO, MgO, ZnO, Na.sub.2 O and K.sub.2 O, provided that the sum of P.sub.2 O.sub.5 and said metal oxide is not less than 90 mol%, said ceramics having a bending strength of at least about 1000 kg/cm.sup.2.

### Claim 2 (depends on 1)

The ceramics of claim 1, wherein said composition is sintered at a temperature approximately between 1000.degree.-1500.degree. C.

### Claim 3 (depends on 1)

The ceramics of claim 1 wherein said frit comprises as said metal oxide in mol% calculated for the frit 0-55% of BaO, 0-55% of CaO, 0-20% of MgO, 0-20% of ZnO, 0-20% of Na.sub.2 O and 0-20% of K.sub.2 O.

### Claim 4 (depends on 1)

The ceramics of claim 1 wherein said powdery material substantially consisting of phosphate of calcium is apatite group, tricalcium phosphate or a mixture thereof, or a mixture of a major part thereof and a minor part of phosphate of calcium other than apatite group and tricalcium phosphate.

### Claim 5 (depends on 4)

The ceramics of claim 4 wherein said apatite group is synthetic or natural apatite or a mixture thereof.

### Claim 6 (depends on 5)

The ceramics of claim 5 wherein said apatite group essentially consists of apatite represented by a formula Ca.sub.5 (OH, F, Cl)(PO.sub.4).sub.3 where OH, F and Cl are comprised at any ratio threrbetween.

### Claim 7 (depends on 6)

The ceramics of claim 6 wherein said apatite group is synthetic apatite produced by precipitation process, dry process, hydro-thermal process or molten process, or a mixture thereof.

### Claim 8 (depends on 5)

The ceramics of claim 5 wherein said apatite group is synthetic hydroxyapatite having a Ca/P atomic ratio of 1.4-1.75 produced by precipitation process, dry process or hydrothermal process.

### Claim 9 (depends on 1)

The ceramics of claim 1 wherein said powdery material substantially consisting of phosphate of calcium is hydroxyapatite, tricalcium phosphate or a mixture thereof.

### Claim 10 (depends on 1)

The ceramics of claim 1, wherein said P.sub.2 O.sub.5 -metal oxide frit further comprises approximately 0-10 mol% calculated for the frit of SiO.sub.2 and/or Al.sub.2 O.sub.3 and the balance of CaO and P.sub.2 O.sub.5.

### Claim 11 (depends on 1)

The ceramics of claim 1 wherein the ceramics comprise impurities not exceeding approximately 0.5% by weight calculated for the ceramics originating from the frit, which impurities comprise SiO.sub.2, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, TiO.sub.2 and/or Fe.sub.2 O.sub.3.

### Claim 12 (depends on 1)

A process for producing the ceramics of claim 1 which comprises a step of melting the components of said frit approximately between 1300.degree.-1400.degree. C., then a step of comminuting the resultant frit.

### Claim 13

A process for producing phosphate of calcium ceramics which comprises a step of mixing 0.5-15% by weight calculated for the ceramics of CaO-P.sub.2 O.sub.5 frit having a Ca/P atomic ratio of 0.2-0.75 and the balance of a powdery material of phosphate of calcium having a Ca/P atomic ratio of 1.4-1.75, and a step of sintering the resulting mixture, said ceramics having a bending strength of at least about 1000 kg/cm.sup.2.

### Claim 14 (depends on 13)

The process of claim 13 wherein said powdery material substantially consisting of phosphate of calcium is apatite group, tricalcium phosphate or a mixture thereof, or a mixture of a major part thereof and a minor part of phosphate of calcium other than apatite group and tricalcium phosphate.

### Claim 15 (depends on 14)

The process of claim 14 wherein said apatite group is synthetic or natural apatite or a mixture thereof.

### Claim 16 (depends on 15)

The process of claim 15 wherein said apatite group essentially consists of apatite represented by a formula Ca.sub.5 (OH, F, Cl)(PO.sub.4).sub.3 where OH, F and Cl are comprised at any ratio therebetween.

### Claim 17 (depends on 16)

The process of claim 16 wherein said apatite group is synthetic apatite produced by precipitation process, dry process, hydrothermal process or melting process, or a mixture thereof.

### Claim 18 (depends on 14)

The process of claim 14 wherein said apatite group is synthetic hydroxyapatite having a Ca/P atomic ratio of 1.4-1.75 procuced by precipitation process, dry process, or hydrothermal process.

### Claim 19 (depends on 13)

The process of claim 13 wherein said powdery material substantially consisting of phosphate of calcium is hydroxyapatite, tricalcium phosphate or a mixture thereof.

### Claim 20 (depends on 13)

The process of claim 13 wherein said CaO-P.sub.2 O.sub.5 frit comprise approximately 0-10 mol% calculated for the frit of SiO.sub.2 and/or Al.sub.2 O.sub.3 and the balance of CaO and P.sub.2 O.sub.5.

### Claim 21 (depends on 13)

The process of claim 13 wherein the ceramics comprise impurities not exceeding approximately 0.5% by weight calculated for the ceramics originating from the frit, which impurities comprise SiO.sub.2, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, TiO.sub.2 and/or Fe.sub.2 O.sub.3.

### Claim 22 (depends on 13)

The process of claim 13 which comprises a step of melting the components of said frit approximately between 1300.degree.-1400.degree. C., then a step of comminuting the resultant frit.

### Claim 23 (depends on 13)

The ceramic product obtained by the process of claim 13, wherein the Ca/P atomic ratio of the CaO-P.sub.2 O.sub.5 frit is more than 0.69 and less than or equal to 0.75.

### Claim 24 (depends on 23)

The ceramics of claim 23, wherein the CaO-P.sub.2 O.sub.5 frit has a Ca/P atomic ratio of 0.70-0.75 and the sintering step is carried out at approximately 1000.degree.-1500.degree. C.