Method of producing alumina particles

• US 6,335,052 B1
• Filed: 01/19/2000
• Issued: 01/01/2002
• Est. Priority Date: 01/20/1999
• Status: Expired due to Fees

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Kato, Tatsuya, Suzuki, Hiroshi
• Primary Examiner(s): Acquah, Samuel A.
• Application Number:
  US09/487,294
• Time in Patent Office: 713 Days
• Field of Search: 427/213.3, 427/213.31, 427/223, 528/481, 528/503, 428/402, 428/403, 428/404, 428/406, 428/407
• US Class Current: 427/213.3
• CPC Class Codes: C01F 7/02 Aluminium oxide; Aluminium hydroxide; Aluminates
• CPC Class Codes: C01F 7/021 After-treatment of oxides or hydroxides
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/84 one phase coated with the other
• CPC Class Codes: C01P 2006/10 Solid density
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]
• CPC Class Codes: Y10T 428/2991 Coated
• CPC Class Codes: Y10T 428/2993 Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]
• CPC Class Codes: Y10T 428/2996 Glass particles or spheres
• CPC Class Codes: Y10T 428/2998 including synthetic resin or polymer

Abstract

Size-enlarged sludge particles 12 having nuclei of objective particles and having a particle size in a range of from 1 μm inclusive to 2000 μm exclusive are mixed with slurry containing fine alumina powder so that a mixture is prepared. Then, the mixture is dried by removal of the water content in the mixture. Then, the mixture is baked at a temperature in a range of from 1200° C. to 1500° C. so that alumina on surfaces of the size-enlarged sludge particles 12 are sintered. By the aforementioned method, light-weight alumina particles can be produced with the particle size controlled well to a uniform value.

Claims

1. A method of producing alumina particles, comprising the steps of:

preparing a mixture of;

(A) core particles, which are formed from a material used as nuclei of said alumina particles, wherein said core particles have a particle size in a range of from 1 μ

m inclusive to 2000 μ

m exclusive, and

(B) slurry which contains fine alumina powder;

drying the resulting mixture by removing water from said mixture; and

baking the resulting dried mixture at a temperature in a range of from 1200°

C. to 1500°

C. to thereby sinter alumina on surfaces of said core particles,

wherein at least a portion of said core particles remain as said nuclei of said alumina particles at the end of said baking.

2. The method of producing alumina particles according to claim 1, wherein said core particles are size-enlarged sludge particles.

3. The method of producing alumina particles according to claim 2, wherein the particle size of said core particles is in a range of from 1 μ

m to 1000 μ

m.

4. The method of producing alumina particles according to claim 1, wherein said core particles are selected from the group consisting of small resin balls and styrene foam particles.

5. The method of producing alumina particles according to claim 4, wherein the particle size of said core particles is in a range of from 20 μ

m inclusive to 2000 μ

m exclusive.

6. The method of producing alumina particles according to any one of claims 1 through 5, wherein said core particles are left as a residue in the inside of the resulting alumina particles after said baking.

7. The method of producing alumina particles according to claim 4, wherein said core particles are left as small resin balls or as foam particles in the inside of the resulting alumina particles after said baking.

8. The method of producing alumina particles according to claim 1, wherein the resulting sintered alumina on the surfaces of said core particles has a thickness in a range of from 1 μ

m to 200 μ

m.

9. The method of producing alumina particles according to claim 1, wherein thickness of sintered alumina on the surface of said core particles is controlled by varying the amount of alumina contained in the slurry.

10. The method of producing alumina particles according to claim 1, wherein thickness of sintered alumina on the surface of said core particles is controlled by varying the temperature during baking within a range of 1200°

C. to 1500°

C.

11. The method of producing alumina particles according to claim 1, wherein thickness of sintered alumina on the surface of said core particles is controlled by varying a time for baking.