Magnetic tape having characterized magnetic layer

Patent metadata

Field	Value
Publication number	US-10854229-B2
Application number	US-201816038847-A
Country	US
Kind code	B2
Filing date	Jul 18, 2018
Priority date	Jul 19, 2017
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

Provided is a magnetic tape in which an Ra measured regarding a surface of a magnetic layer is equal to or smaller than 1.8 nm, Int(110)/Int(114) of a hexagonal ferrite crystal structure obtained by an XRD analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical squareness ratio of the magnetic tape is 0.65 to 1.00, full widths at half maximum of spacing distribution measured by optical interferometry regarding the surface of the back coating layer before and after performing a vacuum heating with respect to the magnetic tape are greater than 0 nm and equal to or smaller than 10.0 nm, and a difference between the spacings measured by optical interferometry regarding the surface of the back coating layer before and after performing the vacuum heating is greater than 0 nm and equal to or smaller than 8.0 nm.

First claim

What is claimed is:

1. A magnetic tape comprising:
a non-magnetic support;
a magnetic layer including ferromagnetic powder, non-magnetic powder, and a binding agent on one surface side of the non-magnetic support; and
a back coating layer including non-magnetic powder and a binding agent on the other surface side of the non-magnetic support,
wherein the ferromagnetic powder is ferromagnetic hexagonal ferrite powder,
a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 1.8 nm,
an intensity ratio Int(110)/Int(114) of a peak intensity Int(110) of a diffraction peak of a (110) plane with respect to a peak intensity Int(114) of a diffraction peak of a (114) plane of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0,
a vertical squareness ratio of the magnetic tape is 0.65 to 1.00,
the back coating layer includes fatty acid ester,
a full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the back coating layer before performing a vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 10.0 nm,
a full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the back coating layer after performing the vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 10.0 nm, and
a difference S after −S before between a spacing S after measured by optical interferometry regarding the surface of the back coating layer after performing the vacuum heating with respect to the magnetic tape and a spacing S before measured by optical interferometry regarding the surface of the back coating layer before performing the vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 8.0 nm.

2. The magnetic tape according to claim 1 ,
wherein the center line average surface roughness Ra measured regarding the surface of the magnetic layer is 1.2 nm to 1.8 nm.

3. The magnetic tape according to claim 1 ,
wherein the vertical squareness ratio is 0.65 to 0.90.

4. The magnetic tape according to claim 1 ,
wherein the full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the back coating layer before performing the vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 8.5 nm.

5. The magnetic tape according to claim 1 ,
wherein the full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the back coating layer after performing the vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 8.5 nm.

6. The magnetic tape according to claim 1 ,
wherein the difference S after −S before is greater than 0 nm and equal to or smaller than 6.0 nm.

7. The magnetic tape according to claim 1 ,
wherein the center line average surface roughness Ra measured regarding the surface of the magnetic layer is 1.2 nm to 1.8 nm,
the vertical squareness ratio is 0.65 to 0.90,
the full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the back coating layer before performing the vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 8.5 nm, and
the difference S after −S before is greater than 0 nm and equal to or smaller than 6.0 nm.

8. The magnetic tape according to claim 1 ,
wherein the non-magnetic powder included in the back coating layer is one or more kinds of non-magnetic powder selected from the group consisting of inorganic powder and carbon black.

9. The magnetic tape according to claim 8 ,
wherein a content of the inorganic powder in the back coating layer is greater than 50.0 parts by mass and equal to or smaller than 100.0 parts by mass with respect to 100.0 parts by mass of a total amount of the non-magnetic powder included in the back coating layer.

10. The magnetic tape according to claim 1 , further comprising:
a non-magnetic layer including non-magnetic powder and a binding agent between the non-magnetic support and the magnetic layer.

Assignees

• Fujifilm Corp

Inventors

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

Classifications

• G11B5/712

  characterised by the surface treatment or coating of magnetic particles · CPC title

• G11B5/7358

  specially adapted for achieving a specific property, e.g. average roughness [Ra] · CPC title

• G11B5/70

  on a base layer · CPC title

• G11B5/7085

  non-magnetic abrasive particles · CPC title

• G11B5/78 Primary

  Tape carriers · CPC title