# US 2010/0167055 A1 · Alpha-alumina powder

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- Number: US 2010/0167055 A1
- Document ID: US20100167055A1
- Status: Published application
- Kind: A1
- Application number: 12/646,347
- Filed: 2009-12-23
- Published: 2010-07-01
- Earliest claimed: 2008-12-25
- Assignees: Sumitomo Chemical Company, Limited
- Inventors: Hirotaka OZAKI; Shinji FUJIWARA; Norifumi AZUMA
- Web page: https://patentgrep.com/patent/US20100167055A1

## CPC

- C01F 7/441: by calcination
- C01P 2004/51: Particles with a specific particle size distribution
- C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer
- C01P 2006/10: Solid density
- C01P 2006/12: Surface area
- C01P 2006/80: Compositional purity
- C01P 2006/82: water content
- Y10T 428/2982: Particulate matter [e.g., sphere, flake, etc.]
- C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00})
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

α-Alumina powder is provided having a purity of 99.99% by weight or more, a specific surface area of from 0.1 to 2.0 m2/g, a relative density of from 80 to 95%, a closed porosity of 4% or less, and a loosed bulk density of 2.4 g/cm3 or more, which is measured by a method for measuring physical properties of alumina powder according to JIS R9301-2-3 (1999).

## Claims

### Claim 1

α-Alumina powder having a purity of 99.99% by weight or more, a specific surface area of from 0.1 to 2.0 m2/g, a relative density of from 80 to 95%, a closed porosity of 4% or less, and a loosed bulk density of 2.4 g/cm3 or more, which is measured by a method for measuring physical properties of alumina powder according to JIS R9301-2-3 (1999).

### Claim 2 (depends on 1)

The α-alumina powder according to claim 1, wherein in a weight-based particle diameter distribution obtained by the dry sieving test according to JIS K0069 (1992), an amount of particles having a particle diameter of less than 75 μm is 10% by weight or more and 60% by weight or less; an amount of particles having a particle diameter exceeding 2.8 mm is 15% by weight or less; and one or more frequency maximum peaks appear in a particle diameter range of 100 μm or more and less than 850 μm, provided that the particle diameter is the largest mesh size of a standard sieve through which α-alumina powder particle cannot pass among the standard sieves according to JIS Z8801 (1987).

### Claim 3 (depends on 2)

The α-Alumina powder according to claim 2, wherein, in the above particle diameter distribution, an amount of particles having a particle diameter of 75 μm or more and less than 100 μm is 10% by weight or less; an amount of particles having a particle diameter of 850 μm or more and less than 1 mm is 10% by weight or less, and one or more frequency maximum peaks appear in a particle diameter range of 1 mm or more, wherein D2 and D1 satisfies the relationship (1):
2D2≦D2≦20D1 (1)
and a ratio of M1 to M2 (M1/M2) is 0.05 or more
wherein D2 is a maximum particle diameter corresponding to the frequency maximum peak having the largest maximum particle diameter among the frequency maximum peaks appearing in the above range and M2 is the maximum value thereof, and D1 is a maximum particle diameter corresponding to the frequency maximum peak having the smallest maximum particle diameter among the frequency maximum peaks appearing in a particle diameter range of 100 μm or more and less than 850 μm and M1 is the maximum value thereof.

### Claim 4 (depends on 3)

The α-Alumina powder according to claim 3, wherein, for the α-alumina powder having a particle diameter of less than 75 μm in said particle diameter distribution, a particle diameter corresponding to a diameter of particles at a cumulative percentage of 50% by weight which is measured by a laser diffraction method is 10 μm or more, and one or more frequency maximum peaks appear in a particle diameter range of 5 μm or more and less than 75 μm.

### Claim 5 (depends on 1)

The α-Alumina powder according to claim 1, wherein each content of Si, Na, Ca, Fe, Cu and Mg is 10 ppm or less.

### Claim 6 (depends on 1)

The α-Alumina powder according to claim 1, which is used as a raw material for the production of single crystal sapphire.