Magnetic recording medium and magnetic recording and reproducing device

Patent metadata

Field	Value
Publication number	US-2020286515-A1
Application number	US-202016809986-A
Country	US
Kind code	A1
Filing date	Mar 5, 2020
Priority date	Mar 6, 2019
Publication date	Sep 10, 2020
Grant date	—

Abstract

The magnetic recording medium includes: a non-magnetic support; and a non-magnetic layer including a non-magnetic powder and a magnetic layer including a ferromagnetic powder on the non-magnetic support in this order, in which a vertical squareness ratio is 0.70 to 1.00, a center line average roughness Ra measured regarding a surface of the magnetic layer with an atomic force microscope is equal to or smaller than 2.5 nm, and an interface variation rate between the magnetic layer and the non-magnetic layer in a cross section image obtained by imaging with a scanning electron microscope is equal to or less than 2.5%.

First claim

What is claimed is:

1 . A magnetic recording medium comprising:
a non-magnetic support; and a non-magnetic layer including a non-magnetic powder and a magnetic layer including a ferromagnetic powder on the non-magnetic support in this order, wherein a vertical squareness ratio is 0.70 to 1.00, a center line average roughness Ra measured regarding a surface of the magnetic layer with an atomic force microscope is equal to or smaller than 2.5 nm, and an interface variation rate between the magnetic layer and the non-magnetic layer in a cross section image obtained by imaging with a scanning electron microscope is equal to or less than 2.5%.

2 . The magnetic recording medium according to claim 1 ,
wherein a void volume of the non-magnetic layer in the cross section image obtained by imaging with a scanning electron microscope is equal to or less than 10.0%.

3 . The magnetic recording medium according to claim 1 ,
wherein the non-magnetic powder of the non-magnetic layer includes carbon black.

4 . The magnetic recording medium according to claim 3 ,
wherein a specific surface area of the carbon black included in the non-magnetic layer is 280 to 500 m 2 /g.

5 . The magnetic recording medium according to claim 3 ,
wherein the non-magnetic layer includes 30.0% by mass or more of the carbon black with respect to a total amount of the non-magnetic powder.

6 . The magnetic recording medium according to claim 1 ,
wherein a thickness of the non-magnetic layer is equal to or less than 1.00 μm.

7 . The magnetic recording medium according to claim 1 ,
wherein the magnetic layer includes a non-magnetic powder.

8 . The magnetic recording medium according to claim 7 ,
wherein the non-magnetic powder of the magnetic layer includes colloidal particles.

9 . The magnetic recording medium according to claim 8 ,
wherein the colloidal particles are silica colloidal particles.

10 . The magnetic recording medium according to claim 1 , further comprising:
a back coating layer including a non-magnetic powder on a surface of the non-magnetic support opposite to a surface provided with the non-magnetic layer and the magnetic layer.

11 . A magnetic recording and reproducing device comprising:
the magnetic recording medium according to claim 1 ; and a magnetic head.

12 . The magnetic recording and reproducing device according to claim 11 ,
wherein a void volume of the non-magnetic layer in the cross section image obtained by imaging with a scanning electron microscope is equal to or less than 10.0%.

13 . The magnetic recording and reproducing device according to claim 11 ,
wherein the non-magnetic powder of the non-magnetic layer includes carbon black.

14 . The magnetic recording and reproducing device according to claim 13 ,
wherein a specific surface area of the carbon black included in the non-magnetic layer is 280 to 500 m 2 /g.

15 . The magnetic recording and reproducing device according to claim 13 ,
wherein the non-magnetic layer includes 30.0% by mass or more of the carbon black with respect to a total amount of the non-magnetic powder.

16 . The magnetic recording and reproducing device according to claim 11 ,
wherein a thickness of the non-magnetic layer is equal to or less than 1.00 μm.

17 . The magnetic recording and reproducing device according to claim 11 ,
wherein the magnetic layer includes a non-magnetic powder.

18 . The magnetic recording and reproducing device according to claim 17 ,
wherein the non-magnetic powder of the magnetic layer includes colloidal particles.

19 . The magnetic recording and reproducing device according to claim 18 ,
wherein the colloidal particles are silica colloidal particles.

20 . The magnetic recording and reproducing device according to claim 11 ,
wherein the magnetic recording medium comprises a back coating layer including a non-magnetic powder on a surface of the non-magnetic support opposite to a surface provided with the non-magnetic layer and the magnetic layer.

Assignees

• Fujifilm Corp

Inventors

• Mori Masahiko

Classifications

• G11B5/7334

  Base layer characterised by composition or structure · CPC title

• G11B5/70

  on a base layer · CPC title

• B05D2601/20

  used for non-pigmentation effect · CPC title

• B05D2252/10

  Applying the material on both sides · CPC title

• B05D2252/02

  of indefinite length · CPC title