Magnetic recording medium

Patent metadata

Field	Value
Publication number	US-11100949-B2
Application number	US-201815996622-A
Country	US
Kind code	B2
Filing date	Jun 4, 2018
Priority date	Jun 9, 2017
Publication date	Aug 24, 2021
Grant date	Aug 24, 2021

Abstract

Provided is a magnetic recording medium including: a non-magnetic support; and a magnetic layer including particles of at least one kind of epsilon type iron oxide-based compound selected from the group consisting of ε-Fe2O3 and a compound represented by Formula (1), an abrasive, and a binding agent, at least on one surface of the non-magnetic support, in which an average equivalent circle diameter of the particles of the epsilon type iron oxide-based compound is 7 nm to 18 nm, an average equivalent circle diameter of the abrasive in a plan view of the magnetic layer is 20 nm to 1,000 nm, and a coefficient of variation of the equivalent circle diameter of the abrasive is 30% to 60%. In Formula (1), A represents at least one kind of metal element other than Fe and a satisfies a relationship of 0<a<2.ε-AaFe2-aO3  (1).

First claim

What is claimed is:

1. A magnetic recording medium comprising:
a non-magnetic support; and
a magnetic layer including particles of at least one kind of epsilon type iron oxide-based compound selected from the group consisting of ε-Fe 2 O 3 and a compound represented by Formula (1), an abrasive, and a binding agent, at least on one surface of the non-magnetic support,
wherein an average equivalent circle diameter of the particles of the epsilon type iron oxide-based compound is 7 nm to 18 nm,
an average equivalent circle diameter of the abrasive is 20 nm to 1,000 nm, and
a coefficient of variation of the equivalent circle diameter of the abrasive is 30% to 60%, in a plan view of an area of a surface of the magnetic layer having a vertical length of 4.3 μm and a horizontal length of 6.3 μm, observed using a scanning electron microscope (SEM):
ε-A a Fe 2-a O 3   (1)

in Formula (1), A represents at least one kind of metal element other than Fe and a satisfies a relationship of 0<a<2.

2. The magnetic recording medium according to claim 1 ,
wherein the epsilon type iron oxide-based compound includes the compound represented by Formula (1), and
A in Formula (1) is at least one kind of metal element selected from the group consisting of Ga, Al, In, Co, Zn, Ti, and Nb.

3. The magnetic recording medium according to claim 1 ,
wherein the average equivalent circle diameter of the abrasive in a plan view of the magnetic layer is 30 nm to 800 nm.

4. The magnetic recording medium according to claim 3 ,
wherein the average equivalent circle diameter of the abrasive in a plan view of the magnetic layer is 110 nm to 200 nm.

5. The magnetic recording medium according to claim 1 ,
wherein a recording system is a linear recording system.

6. The magnetic recording medium according to claim 1 , which is used in electromagnetic wave assist recording.

Assignees

• Fujifilm Corp

Inventors

• Shirata Masashi
• Fujimoto Takashi

Classifications

• G11B5/714

  characterised by the dimension of the magnetic particles · CPC title

• G11B5/70642

  iron oxides · CPC title

• G11B5/7085

  non-magnetic abrasive particles · CPC title

• G11B5/78 Primary

  Tape carriers · CPC title

• G11B5/70621

  containing Co metal or alloys · CPC title