Magnetic recording medium

Patent metadata

Field	Value
Publication number	US-2018358043-A1
Application number	US-201815986882-A
Country	US
Kind code	A1
Filing date	May 23, 2018
Priority date	Jun 9, 2017
Publication date	Dec 13, 2018
Grant date	—

Abstract

A magnetic recording medium includes: a non-magnetic support; and a magnetic layer including a binding agent and a ferromagnetic powder including at least one epsilon-type iron oxide compound selected from the group consisting of ε-Fe 2 O 3 and compound represented by Formula (1) (A represents at least one metal element other than Fe, and a satisfies 0<a<2), in which a value of magnetic field Hc with respect to magnetic field Hc′ is from 0.6 to 1.0, and Hc′ satisfies Expression (II): 119 kA/m<Hc′<2380 kA/m. The magnetic field Hc′ is a magnetic field when the value of Expression (I): d 2 M/dH 2 is zero, wherein a magnetization M, which is obtained by a magnetic field-magnetization curve obtained by measurement under specific conditions, is subjected to second derivative with respect to an applied magnetic field H, and magnetic field Hc is a magnetic field when the magnetization is zero in the curve.
ε-A a Fe 2-a O 3   (1)

First claim

What is claimed is:

1 . A magnetic recording medium, comprising:
a non-magnetic support; and a magnetic layer that is provided on the non-magnetic support and that comprises a ferromagnetic powder and a binding agent, the ferromagnetic powder comprising at least one epsilon-type iron oxide compound selected from the group consisting of ε-Fe 2 O 3 and a compound represented by the following Formula (1), wherein a value of a magnetic field Hc with respect to a magnetic field Hc′ is from 0.6 to 1.0, and Hc′ satisfies the following Expression (II), wherein the magnetic field Hc′ is a magnetic field when the value of the following Expression (I) is zero, wherein a magnetization M, which is obtained by a magnetic field-magnetization curve obtained by measurement at a maximum applied magnetic field of 359 kA/m, a temperature of 296 K, and a magnetic field sweeping speed of 1.994 kA/m/s, is subjected to a second derivative with respect to an applied magnetic field H, and wherein the magnetic field Hc is a magnetic field when the magnetization is zero in the magnetic field-magnetization curve:
d 2 M/dH 2   Expression (I)

119 kA/m< Hc ′<2380 kA/m  Expression (II)

ε-A a Fe 2-a O 3   (1)

wherein, in Formula (1), A represents at least one 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 binding agent comprises a binding agent having a crosslinked structure.

3 . The magnetic recording medium according to claim 1 , wherein a value of Hc with respect to Hc′ is from 0.65 to 1.0.

4 . The magnetic recording medium according to claim 1 , wherein a value of Hc with respect to Hc′ is from 0.71 to 1.0.

5 . The magnetic recording medium according to claim 1 , wherein a content of the binding agent is 5 parts by mass to 30 parts by mass with respect to 100 parts by mass of the ferromagnetic powder.

6 . The magnetic recording medium according to claim 1 , wherein a mass ratio of mass of a nonvolatile component with respect to mass of the ferromagnetic powder in the magnetic layer is from 0.15 to 1.8.

7 . The magnetic recording medium according to claim 1 , wherein a thickness of the magnetic layer is 10 nm to 350 nm.

8 . The magnetic recording medium according to claim 1 , wherein A in Formula (1) is at least one metal element selected from the group consisting of Ga, Al, In, Nb, Co, Zn, Ni, Mn, Ti, and Sn.

9 . The magnetic recording medium according to claim 8 , wherein the compound represented by Formula (1) comprises Ga, and an atomic composition percentage of Ga atoms is 5 atom % to 50 atom % with respect to Fe atoms.

Assignees

• Fujifilm Corp

Inventors

• Naoi Kenji
• Fujimoto Takashi
• Shirata Masashi

Classifications

• G11B5/70615 Primary

  containing Fe metal or alloys (G11B5/70621 takes precedence) · CPC title

• G11B5/70621 Primary

  containing Co metal or alloys · CPC title

• G11B5/70642

  iron oxides · CPC title

• G11B5/70

  on a base layer · CPC title