MAGNETIC TAPE

• US 20180286443A1
• Filed: 03/14/2018
• Published: 10/04/2018
• Est. Priority Date: 03/29/2017
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: OZAWA, Eiki, KASADA, Norihito
• Granted Patent: US 10,438,623 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 5/70615 containing Fe metal or alloys G11B5/70621 takes precedence
• CPC Class Codes: G11B 5/70626 containing non-metallic substances
• CPC Class Codes: G11B 5/71 characterised by the lubricant
• CPC Class Codes: G11B 5/78 Tape carriers

Abstract

The magnetic tape has the total thickness of a non-magnetic layer and a magnetic layer of 0.60 μm or smaller, the magnetic layer including an abrasive and fatty acid ester, a percentage of a plan view maximum area of the abrasive confirmed in a region having a size of 4.3 μm×6.3 μm of the surface of the magnetic layer with respect to the total area of the region, obtained by plane observation performed by using an SEM of 0.02% or greater and less than 0.06%, full widths at half maximum of spacing distribution measured by optical interferometry regarding a surface of the magnetic layer before and after performing a vacuum heating with respect to the magnetic tape of greater than 0 nm and 7.0 nm or smaller, and a difference between spacings before and after the vacuum heating of greater than 0 nm and 8.0 nm or smaller.

Claims

1. A magnetic tape comprising:

a non-magnetic support;

a non-magnetic layer including non-magnetic powder and a binding agent on the non-magnetic support; and

a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic layer,

wherein a total thickness of the non-magnetic layer and the magnetic layer is equal to or smaller than 0.60 μ

m,

the magnetic layer includes an abrasive and fatty acid ester,

a percentage of a plan view maximum area of the abrasive confirmed in a region having a size of 4.3 μ

m×

6.3 μ

m of a surface of the magnetic layer with respect to the total area of the region, obtained by plane observation performed by using a scanning electron microscope is equal to or greater than 0.02% and less than 0.06%,

a full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the magnetic layer before performing a vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 7.0 nm,

a full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the magnetic layer after performing the vacuum heating with respect to the magnetic tape 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 measured by optical interferometry regarding the surface of the magnetic 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 magnetic 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 percentage of a plan view maximum area of the abrasive confirmed in a region having a size of 4.3 μ

m×

6.3 μ

m of the surface of the magnetic layer with respect to the total area of the region, obtained by plane observation performed by using a scanning electron microscope is 0.02% to 0.05%.

3. The magnetic tape according to claim 1,

wherein the total thickness of the non-magnetic layer and the magnetic layer is 0.20 μ

m to 0.60 μ

m.

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 magnetic layer before performing the vacuum heating with respect to the magnetic tape is 3.0 nm to 7.0 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 magnetic layer after performing the vacuum heating with respect to the magnetic tape is 3.0 nm to 7.0 nm.

6. The magnetic tape according to claim 1,

wherein the difference S_after−

S_before is 2.0 nm to 8.0 nm.

7. The magnetic tape according to claim 1,

wherein a BET specific surface area of the abrasive is 14 to 40 m²/g.

8. The magnetic tape according to claim 1,

wherein the abrasive is alumina powder.

9. The magnetic tape according to claim 1,

wherein the magnetic layer includes an aromatic hydrocarbon compound including a phenolic hydroxyl group.

10. The magnetic tape according to claim 1,

wherein the ferromagnetic powder is ferromagnetic hexagonal ferrite powder.

11. The magnetic tape according to claim 10,

wherein the ferromagnetic hexagonal ferrite powder includes Al.