Magnetic recording medium, magnetic tape cartridge, and magnetic recording and reproducing device

Patent metadata

Field	Value
Publication number	US-2021350826-A1
Application number	US-202117241078-A
Country	US
Kind code	A1
Filing date	Apr 27, 2021
Priority date	May 8, 2020
Publication date	Nov 11, 2021
Grant date	—

Abstract

The magnetic recording medium includes a non-magnetic support; a non-magnetic layer which contains a non-magnetic powder and is provided on the non-magnetic support; and a magnetic layer which contains a ferromagnetic powder and is provided on the non-magnetic layer, in which a thickness of the non-magnetic layer is less than 0.7 μm, and an average 5-point peak height Rpm is 30 nm or lower and the number of projections having a height of 5 nm or higher is 5,000 or more, as obtained by using an atomic force microscope in a measurement region of 90 μm square on a surface of the magnetic layer.

First claim

What is claimed is:

1 . A magnetic recording medium comprising:
a non-magnetic support; a non-magnetic layer which contains a non-magnetic powder and is provided on the non-magnetic support; and a magnetic layer which contains a ferromagnetic powder and is provided on the non-magnetic layer, wherein a thickness of the non-magnetic layer is less than 0.7 μm, and an average 5-point peak height Rpm is 30 nm or lower and the number of projections having a height of 5 nm or higher is 5,000 or more, as obtained by using an atomic force microscope in a measurement region of 90 μm square on a surface of the magnetic layer.

2 . The magnetic recording medium according to claim 1 ,
wherein the number of dark regions having an equivalent circle diameter of 300 μm or greater is smaller than 5 per an area of 1,490 μm 2 in a binarized image of a backscattered electron image obtained by imaging the surface of the magnetic layer with a scanning electron microscope at an acceleration voltage of 2 kV.

3 . The magnetic recording medium according to claim 1 ,
wherein the magnetic layer contains colloidal particles.

4 . The magnetic recording medium according to claim 3 ,
wherein the colloidal particles are silica colloidal particles.

5 . The magnetic recording medium according to claim 1 ,
wherein the thickness of the non-magnetic layer is 0.1 μm to 0.6 am.

6 . The magnetic recording medium according to claim 1 ,
wherein the Rpm is 15 nm to 30 nm.

7 . The magnetic recording medium according to claim 1 ,
wherein the number of projections having a height of 5 nm or higher is 5,000 to 8,000.

8 . The magnetic recording medium according to claim 1 , further comprising a back coating layer which contains a non-magnetic powder and is provided on a surface side of the non-magnetic support opposite to a surface side on which the non-magnetic layer and the magnetic layer are provided.

9 . The magnetic recording medium according to claim 1 ,
wherein the magnetic recording medium is a magnetic tape.

10 . A magnetic tape cartridge comprising the magnetic recording medium according to claim 9 .

11 . The magnetic tape cartridge according to claim 10 ,
wherein the number of dark regions having an equivalent circle diameter of 300 μm or greater is smaller than 5 per an area of 1,490 μm 2 in a binarized image of a backscattered electron image obtained by imaging the surface of the magnetic layer with a scanning electron microscope at an acceleration voltage of 2 kV.

12 . The magnetic tape cartridge according to claim 10 ,
wherein the thickness of the non-magnetic layer is 0.1 μm to 0.6 μm.

13 . The magnetic tape cartridge according to claim 10 ,
wherein the Rpm is 15 nm to 30 nm.

14 . The magnetic tape cartridge according to claim 10 ,
wherein the number of projections having a height of 5 nm or higher is 5,000 to 8,000.

15 . A magnetic recording and reproducing device comprising the magnetic recording medium according to claim 1 .

16 . The magnetic recording and reproducing device according to claim 15 ,
wherein the number of dark regions having an equivalent circle diameter of 300 μm or greater is smaller than 5 per an area of 1,490 μm 2 in a binarized image of a backscattered electron image obtained by imaging the surface of the magnetic layer with a scanning electron microscope at an acceleration voltage of 2 kV.

17 . The magnetic recording and reproducing device according to claim 15 , wherein the thickness of the non-magnetic layer is 0.1 μm to 0.6 μm.

18 . The magnetic recording and reproducing device according to claim 15 , wherein the Rpm is 15 nm to 30 nm.

19 . The magnetic recording and reproducing device according to claim 15 , wherein the number of projections having a height of 5 nm or higher is 5,000 to 8,000.

Assignees

• Fujifilm Corp

Inventors

• Mori Masahiko

Classifications

• G11B5/7356

  comprising non-magnetic particles in the back layer, e.g. particles of TiO2, ZnO or SiO2 · CPC title

• G11B5/714

  characterised by the dimension of the magnetic particles · CPC title

• G11B5/70678 Primary

  Ferrites · CPC title

• G11B5/00817

  on longitudinal tracks only, e.g. for serpentine format recording · CPC title