US2017040032A1PendingUtilityA1

Ferromagnetic hexagonal ferrite powder, method of manufacturing the same, and magnetic recording medium

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Assignee: FUJIFILM CORPPriority: Sep 30, 2013Filed: Oct 20, 2016Published: Feb 9, 2017
Est. expirySep 30, 2033(~7.2 yrs left)· nominal 20-yr term from priority
Inventors:Yoichi Hosoya
B32B 2307/208C01P 2004/54C01P 2004/10G11B 5/70678B32B 5/16C01P 2004/64C01P 2004/20Y10T428/2982C01G 49/02C01P 2006/12C01P 2006/42C01G 49/0036C01P 2004/30G11B 5/714B32B 2429/02Y02P20/54
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Claims

Abstract

An aspect of the present invention relates to ferromagnetic hexagonal ferrite powder, the average particle size of which is equal to or less than 20 nm, and which comprises, on a particle number basis, equal to or more than 50% of ellipsoid hexagonal ferrite powders satisfying relation (1): 1.2<major axis length/minor axis length<2.0  (1).

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
         1 . A magnetic recording medium, which comprises a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, wherein the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, the average particle size of which is equal to or less than 20 nm, and which comprises, on a particle number basis, equal to or more than 50% of ellipsoid hexagonal ferrite powders satisfying relation (1):
   1.2<major axis length/minor axis length<2.0  (1).
   
     
     
         2 . The magnetic recording medium according to  claim 1 , wherein an average particle size of the ferromagnetic hexagonal ferrite powder provided ranges from 5 nm to 20 nm. 
     
     
         3 . The magnetic recording medium according to  claim 1 , wherein the ferromagnetic hexagonal ferrite powder comprises, on a particle number basis, equal to or less than 45% of spherical hexagonal ferrite particles satisfying relation (2):
   major axis length/minor axis length≦1.2  (2).
   
     
     
         4 . The magnetic recording medium according to  claim 1 , wherein the ferromagnetic hexagonal ferrite powder comprises, on a particle number basis, equal to or less than 5% of acicular hexagonal ferrite particles satisfying relation (3):
   major axis length/minor axis length≧2.0  (3).
   
     
     
         5 . The magnetic recording medium according to  claim 3 , wherein the ferromagnetic hexagonal ferrite powder comprises, on a particle number basis, equal to or less than 5% of acicular hexagonal ferrite particles satisfying relation (3):
   major axis length/minor axis length≧2.0  (3).

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