Magnetic recording medium

• US 11,100,949 B2
• Filed: 06/04/2018
• Issued: 08/24/2021
• Est. Priority Date: 06/09/2017
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Shirata, Masashi, Fujimoto, Takashi
• Primary Examiner(s): Rickman, Holly
• Application Number:
  US15/996,622
• Publication Number:
  US 20180358046A1
• Time in Patent Office: 1,177 Days
• CPC Class Codes: G11B 5/70621 containing Co metal or alloys
• CPC Class Codes: G11B 5/70642 iron oxides
• CPC Class Codes: G11B 5/7085 non-magnetic abrasive particles
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles
• CPC Class Codes: G11B 5/78 Tape carriers

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-A_aFe_2-aO₃  (1).

Claims

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

-Fe₂O₃ 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 μ

m and a horizontal length of 6.3 μ

m, observed using a scanning electron microscope (SEM);

ε

-A_aFe_2-aO₃ 

 

(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.