MAGNETIC TAPE

• US 20190027181A1
• Filed: 07/18/2018
• 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, TADA, Toshio, KASADA, Norihito, KUROKAWA, Takuto
• Granted Patent: US 10,854,229 B2
• Time in Patent Office: Days
• CPC Class Codes: G11B 5/00813 magnetic tapes
• 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 5/7356 comprising non-magnetic particles in the back layer, e.g. particles of TiO2, ZnO or SiO2
• CPC Class Codes: G11B 5/7358 specially adapted for achieving a specific property, e.g. average roughness [Ra]
• CPC Class Codes: G11B 5/78 Tape carriers
• CPC Class Codes: G11B 5/84 Processes or apparatus specially adapted for manufacturing record carriers

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.

Claims

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 mu 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 mu, 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.