Magnetic recording medium having characterized magnetic layer

Patent metadata

Field	Value
Publication number	US-10854232-B2
Application number	US-201816037681-A
Country	US
Kind code	B2
Filing date	Jul 17, 2018
Priority date	Jul 19, 2017
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

The magnetic recording medium includes a magnetic layer which contains ferromagnetic hexagonal ferrite powder and a binder, in which the magnetic layer contains an abrasive and a fatty acid ester, Int (110)/Int (114) of a crystal structure of the hexagonal ferrite, determined by performing XRD analysis on the magnetic layer by using an In-Plane method, is equal to or higher than 0.5 and equal to or lower than 4.0, a squareness ratio of the magnetic recording medium in a vertical direction is equal to or higher than 0.65 and equal to or lower than 1.00, FWHM before and FWHM after is greater than 0 nm and equal to or smaller than 7.0 nm, and a difference between spacings measured within a surface of the magnetic layer by an optical interference method before and after the heating in a vacuum is greater than 0 nm and equal to or smaller than 8.0 nm.

First claim

What is claimed is:

1. A magnetic recording medium comprising:
a non-magnetic support; and
a magnetic layer which is provided on the support and contains ferromagnetic powder and a binder,
wherein the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, the magnetic layer contains an abrasive and a fatty acid ester, an intensity ratio (Int (110)/Int (114)) of a peak intensity Int (110) of a diffraction peak of (110) plane of a crystal structure of the hexagonal ferrite, determined by performing X-ray diffraction analysis on the magnetic layer by using an In-Plane method, to a peak intensity Int (114) of a diffraction peak of (114) plane of the crystal structure is equal to or higher than 0.5 and equal to or lower than 4.0,
a squareness ratio of the magnetic recording medium in a vertical direction is equal to or higher than 0.65 and equal to or lower than 1.00,
a full width at half maximum of a spacing distribution measured within a surface of the magnetic layer by an optical interference method before the magnetic recording medium is heated in a vacuum is greater than 0 nm and equal to or smaller than 7.0 nm,
a full width at half maximum of a spacing distribution measured within the surface of the magnetic layer by an optical interference method after the magnetic recording medium is heated in a vacuum is greater than 0 nm and equal to or smaller than 7.0 nm, and
a difference (S after −S before ) between a spacing S after , which is measured within a surface of the magnetic layer by an optical interference method after the magnetic recording medium is heated in a vacuum, and a spacing S before , which is measured within the surface of the magnetic layer by an optical interference method before the magnetic recording medium is heated in a vacuum, is greater than 0 nm and equal to or smaller than 8.0 nm.

2. The magnetic recording medium according to claim 1 ,
wherein the squareness ratio in a vertical direction is equal to or higher than 0.65 and equal to or lower than 0.90.

3. The magnetic recording medium according to claim 1 ,
wherein the full width at half maximum of a spacing distribution measured within the surface of the magnetic layer by an optical interference method before the magnetic recording medium is heated in a vacuum is equal to or greater than 3.0 nm and equal to or smaller than 7.0 nm.

4. The magnetic recording medium according to claim 2 ,
wherein the full width at half maximum of a spacing distribution measured within the surface of the magnetic layer by an optical interference method before the magnetic recording medium is heated in a vacuum is equal to or greater than 3.0 nm and equal to or smaller than 7.0 nm.

5. The magnetic recording medium according to claim 1 ,
wherein the full width at half maximum of the spacing distribution measured within the surface of the magnetic layer by an optical interference method after the magnetic recording medium is heated in a vacuum is equal to or greater than 3.0 nm and equal to or smaller than 7.0 nm.

6. The magnetic recording medium according to claim 2 ,
wherein the full width at half maximum of the spacing distribution measured within the surface of the magnetic layer by an optical interference method after the magnetic recording medium is heated in a vacuum is equal to or greater than 3.0 nm and equal to or smaller than 7.0 nm.

7. The magnetic recording medium according to claim 3 ,
wherein the full width at half maximum of the spacing distribution measured within the surface of the magnetic layer by an optical interference method after the magnetic recording medium is heated in a vacuum is equal to or greater than 3.0 nm and equal to or smaller than 7.0 nm.

8. The magnetic recording medium according to claim 4 ,
wherein the full width at half maximum of the spacing distribution measured within the surface of the magnetic layer by an optical interference method after the magnetic recording medium is heated in a vacuum is equal to or greater than 3.0 nm and equal to or smaller than 7.0 nm.

9. The magnetic recording medium according to claim 1 ,
wherein the difference S after −S before is equal to or greater than 2.0 nm and equal to or smaller than 8.0 nm.

10. The magnetic recording medium according to claim 2 ,
wherein the difference S after −S before is equal to or greater than 2.0 nm and equal to or smaller than 8.0 nm.

11. The magnetic recording medium according to claim 3 ,
wherein the difference S after −S before is equal to or greater than 2.0 nm and equal to or smaller than 8.0 nm.

12. The magnetic recording medium according to claim 4 ,
wherein the difference S after −S before is equal to or greater than 2.0 nm and equal to or smaller than 8.0 nm.

13. The magnetic recording medium according to claim 5 ,
wherein the difference S after −S before is equal to or greater than 2.0 nm and equal to or smaller than 8.0 nm.

14. The magnetic recording medium according to claim 6 ,
wherein the difference S after −S before is equal to or greater than 2.0 nm and equal to or smaller than 8.0 nm.

15. The magnetic recording medium according to claim 7 ,
wherein the difference S after −S before is equal to or greater than 2.0 nm and equal to or smaller than 8.0 nm.

16. The magnetic recording medium according to claim 8 ,
wherein the difference S after −S before is equal to or greater than 2.0 nm and equal to or smaller than 8.0 nm.

17. The magnetic recording medium according to claim 1 , further comprising:
a non-magnetic layer containing non-magnetic powder and a binder between the non-magnetic support and the magnetic layer.

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

19. The magnetic recording medium according to claim 1 , which is a magnetic tape.

Assignees

• Fujifilm Corp

Inventors

• Ozawa Eiki
• Kasada Norihito
• Tada Toshio
• Kurokawa Takuto

Classifications

• G11B5/78 Primary

  Tape carriers · CPC title

• G11B5/735

  characterised by the back layer {(magnetic recording media substrates G11B5/739)} · CPC title

• G11B5/71

  characterised by the lubricant · CPC title

• G11B5/70678

  Ferrites · CPC title

• G11B5/00817

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