HEXAGONAL FERRITE MAGNETIC PARTICLE AND METHOD OF MANUFACTURING THE SAME, AND MAGNETIC RECORDING MEDIUM

• US 20110244272A1
• Filed: 03/31/2011
• Published: 10/06/2011
• Est. Priority Date: 03/31/2010
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: SUZUKI, Hiroyuki, YAMAZAKI, Nobuo
• Granted Patent: US 8,545,714 B2
• Time in Patent Office: Days
• US Class Current: 428/842.8
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 49/0018 Mixed oxides or hydroxides, C01G49/0009 takes precedence
• CPC Class Codes: C01G 49/0036 containing one alkaline earth metal, magnesium or lead
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/42 Magnetic properties
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3218 Aluminium (oxy)hydroxides, e.g. boehmite, gibbsite, alumina sol
• CPC Class Codes: C04B 2235/3251 Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3274 Ferrites
• CPC Class Codes: C04B 2235/3275 Cobalt oxides, cobaltates or cobaltites or oxide forming salts thereof, e.g. bismuth cobaltate, zinc cobaltite
• CPC Class Codes: C04B 2235/3284 Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
• CPC Class Codes: C04B 2235/3409 Boron oxide, borates, boric acids, or oxide forming salts thereof, e.g. borax
• CPC Class Codes: C04B 2235/5409 expressed by specific surface values
• CPC Class Codes: C04B 2235/5454 nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 2235/767 Hexagonal symmetry, e.g. beta-Si3N4, beta-Sialon, alpha-SiC or hexa-ferrites
• CPC Class Codes: C04B 35/2683 Other ferrites containing alkaline earth metals or lead
• CPC Class Codes: C04B 35/6262 of calcined, sintered clinker or ceramics
• CPC Class Codes: C04B 35/62665 Flame, plasma or melting treatment
• CPC Class Codes: C04B 35/62813 Alumina or aluminates
• CPC Class Codes: G11B 5/70678 Ferrites
• CPC Class Codes: G11B 5/712 : characterised by the surface treatment or coating of magnetic particles
• CPC Class Codes: G11B 5/714 : characterised by the dimension of the magnetic particles
• CPC Class Codes: H01F 1/0315 : Ferrites
• CPC Class Codes: H01F 1/11 : in the form of particles for magnetic record carriers G11B5/70626
• CPC Class Codes: Y10T 428/2982 : Particulate matter [e.g., sphere, flake, etc.]

Abstract

An aspect of the present invention relates to a method of manufacturing a hexagonal ferrite magnetic particle comprising melting an Al-containing starting material mixture to prepare a melt and quenching the melt to obtain an amorphous material; subjecting the amorphous material to heat treatment to cause a hexagonal ferrite magnetic particle to precipitate in a product obtained by the heat treatment; collecting a hexagonal ferrite magnetic particle by subjecting the product to treatment with an acid and washing, wherein the hexagonal ferrite magnetic particle collected has a particle size ranging from 15 to 30 nm, comprises 0.6 to 8.0 weight percent of Al, based on Al₂O₃ conversion, relative to a total weight of the particle, and Al adheres to a surface of the hexagonal ferrite magnetic particle.

Claims

1. A method of manufacturing a hexagonal ferrite magnetic particle comprising:

melting an Al-containing starting material mixture to prepare a melt and quenching the melt to obtain an amorphous material;

subjecting the amorphous material to heat treatment to cause a hexagonal ferrite magnetic particle to precipitate in a product obtained by the heat treatment;

collecting a hexagonal ferrite magnetic particle by subjecting the product to treatment with an acid and washing, wherein the hexagonal ferrite magnetic particle collected has a particle size ranging from 15 to 30 nm, comprises 0.6 to 8.0 weight percent of Al, based on Al₂O₃ conversion, relative to a total weight of the particle, and Al adheres to a surface of the hexagonal ferrite magnetic particle.

2. The method of manufacturing according to claim 1, wherein the starting material mixture comprises an Al compound as a glass-forming component.

3. A hexagonal ferrite magnetic particle prepared by the method of manufacturing according to claim 1.

4. The hexagonal ferrite magnetic particle according to claim 3, which has a coercive force ranging from 159 to 318 kA/m.

5. The hexagonal ferrite magnetic particle according to claim 3, on which surface Al is present as an oxide.

6. The hexagonal ferrite magnetic particle according to claim 3, which is comprised of a primary particle of hexagonal ferrite to which surface Al adheres.

7. The hexagonal ferrite magnetic particle according to claim 3, which has a specific surface area ranging from 50 to 100 m²/g.

8. The hexagonal ferrite magnetic particle according to claim 3, which is a barium ferrite magnetic particle.

9. A magnetic recording medium comprising a magnetic layer containing a ferromagnetic material and a binder on a nonmagnetic support, wherein

the ferromagnetic material comprises the hexagonal ferrite magnetic particle according to claim 3.