MAGNETIC TAPE

• US 20180240492A1
• Filed: 02/20/2018
• Published: 08/23/2018
• Est. Priority Date: 02/20/2017
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: KASADA, Norihito
• Granted Patent: US 10,424,330 B2
• Time in Patent Office: Days
• CPC Class Codes: G11B 5/708 characterised by addition of non-magnetic particles to the layer
• CPC Class Codes: G11B 5/712 characterised by the surface treatment or coating of magnetic particles
• CPC Class Codes: G11B 5/735 characterised by the back layer magnetic recording media substrates G11B5/739
• 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 5/78 Tape carriers

Abstract

The magnetic tape includes a back coating layer having a thickness equal to or smaller than 0.30 μm and including fatty acid ester, a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding a surface of the back coating layer is equal to or smaller than 0.060, a full width 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 is respectively greater than 0 nm and equal to or smaller than 10.0 nm, and a difference between a spacing measured by optical interferometry regarding the surface of the back coating layer after performing the vacuum heating and a spacing measured before 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 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 a thickness of the back coating layer is equal to or smaller than 0.30 μ

m,

the back coating layer includes fatty acid ester,

a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the back coating layer is equal to or smaller than 0.060,

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 logarithmic decrement is 0.010 to 0.060.

3. The magnetic tape according to claim 1,

wherein the thickness of the back coating layer is 0.10 μ

m to 0.30 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 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 8.0 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 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 8.0 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 logarithmic decrement is 0.010 to 0.060,

the thickness of the back coating layer is 0.10 μ

m to 0.30 μ

m,

the 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 8.0 nm,

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 8.0 nm, and

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 8.0 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 the 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 the 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.