MAGNETIC RECORDING MEDIUM

• US 20190027179A1
• Filed: 07/17/2018
• Published: 01/24/2019
• Est. Priority Date: 07/19/2017
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: OZAWA, Eiki, KASADA, Norihito, TADA, Toshio, KUROKAWA, Takuto
• Granted Patent: US 10,854,232 B2
• Time in Patent Office: Days
• CPC Class Codes: G11B 5/00817 on longitudinal tracks only, e.g. for serpentine format recording
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/70678 Ferrites
• CPC Class Codes: G11B 5/7085 non-magnetic abrasive particles
• CPC Class Codes: G11B 5/71 characterised by the lubricant
• CPC Class Codes: G11B 5/712 characterised by the surface treatment or coating of magnetic particles
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles
• CPC Class Codes: G11B 5/735 characterised by the back layer magnetic recording media substrates G11B5/739
• CPC Class Codes: G11B 5/78 Tape carriers
• CPC Class Codes: G11B 5/84 Processes or apparatus specially adapted for manufacturing record carriers

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.

Claims

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.