MAGNETIC TAPE AND METHOD OF MANUFACTURING THE SAME

• US 20170053669A1
• Filed: 08/19/2016
• Published: 02/23/2017
• Est. Priority Date: 08/21/2015
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: KASADA, Norihito
• Granted Patent: US 10,026,433 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/7085 non-magnetic abrasive particles
• CPC Class Codes: G11B 5/78 Tape carriers
• CPC Class Codes: G11B 5/842 Coating a support with a liquid magnetic dispersion

Abstract

The magnetic tape has a nonmagnetic layer containing nonmagnetic powder and binder on a nonmagnetic support, and has a magnetic layer containing ferromagnetic powder and binder on the nonmagnetic layer, wherein the combined thickness of the magnetic layer and the nonmagnetic layer is less than or equal to 0.80 μm; and the logarithmic decrement as determined by a pendulum viscoelasticity test on the surface on the magnetic layer side of the magnetic tape is less than or equal to 0.050 and the coefficient of friction as measured on a base portion of the surface on the magnetic layer side is less than or equal to 0.35.

Claims

1. A magnetic tape,

which comprises a nonmagnetic layer comprising nonmagnetic powder and binder on a nonmagnetic support, and comprises a magnetic layer comprising ferromagnetic powder and binder on the nonmagnetic layer, wherein:

a combined thickness of the magnetic layer and the nonmagnetic layer is less than or equal to 0.80 μ

m; and

a logarithmic decrement as determined by a pendulum viscoelasticity test on a surface on the magnetic layer side of the magnetic tape is less than or equal to 0.050 and a coefficient of friction as measured on a base portion of the surface on the magnetic layer side is less than or equal to 0.35.

2. The magnetic tape according to claim 1,

wherein the logarithmic decrement is greater than or equal to 0.010 but less than or equal to 0.050.

3. The magnetic tape according to claim 1,

wherein the ferromagnetic powder is selected from the group consisting of ferromagnetic hexagonal ferrite powder and ferromagnetic metal powder.

4. The magnetic tape according to claim 1,

wherein the magnetic layer further comprises nonmagnetic powder.

5. The magnetic tape according to claim 4,

wherein the nonmagnetic powder that is contained in the magnetic layer comprises two or more kinds of nonmagnetic powder with differing Mohs hardness.

6. The magnetic tape according to claim 4,

wherein the nonmagnetic powder contained in the magnetic layer comprises inorganic powder with Mohs hardness of higher than 8.

7. The magnetic tape according to claim 4,

wherein the nonmagnetic powder contained in the magnetic layer comprises nonmagnetic colloidal particles.

8. A method of manufacturing a magnetic tape,

wherein the magnetic tape is a magnetic tape which comprises a nonmagnetic layer comprising nonmagnetic powder and binder on a nonmagnetic support, and comprises a magnetic layer comprising ferromagnetic powder and binder on the nonmagnetic layer, wherein:

a combined thickness of the magnetic layer and the nonmagnetic layer is less than or equal to 0.80 in; and

a logarithmic decrement as determined by a pendulum viscoelasticity test on a surface on the magnetic layer side of the magnetic tape is less than or equal to 0.050 and a coefficient of friction as measured on a base portion of the surface on the magnetic layer side is less than or equal to 0.35, and

the method comprises;

forming of a nonmagnetic layer and forming of a magnetic layer, wherein

the forming of a magnetic layer comprises;

coating a magnetic layer-forming composition comprising ferromagnetic powder, binder, a curing agent, and solvent on a nomnagnetic layer to form a coating layer,

heating and drying the coating layer by a heat treatment, and

curing the coating layer by subjecting the coating layer to a curing treatment;

with cooling the coating layer after the coating but before the heating and drying, and

burnishing the surface of the coating layer after the heating and drying but before the curing.

9. The method of manufacturing a magnetic tape according to claim 8,

wherein the cooling is conducted by placing the coating layer in a cooling environment of −

10°

C. to 0°

C.

10. The method of manufacturing a magnetic tape according to claim 8,

wherein the solvent that is contained in the magnetic layer-forming composition comprises ketone solvent.

11. The method of manufacturing a magnetic tape according to claim 8,

wherein the curing agent is a thermosetting compound and the curing is conducted by a heat treatment.

12. The method of manufacturing a magnetic tape according to claim 11,

wherein the thermosetting compound is polyisocyanate.

13. The method of manufacturing a magnetic tape according to claim 8,

wherein a surface-smoothing is conducted between the burnishing and the curing.

14. The method of manufacturing a magnetic tape according to claim 8,

wherein the logarithmic decrement is greater than or equal to 0.010 but less than or equal to 0.050.

15. The method of manufacturing a magnetic tape according to claim 8,

wherein the ferromagnetic powder is selected from the group consisting of ferromagnetic hexagonal ferrite powder and ferromagnetic metal powder.

16. The method of manufacturing a magnetic tape according to claim 8,

wherein the magnetic layer further comprises nonmagnetic powder.

17. The method of manufacturing a magnetic tape according to claim 16,

wherein the nonmagnetic powder that is contained in the magnetic layer comprises two or more kinds of nonmagnetic powder with differing Mohs hardness.

18. The method of manufacturing a magnetic tape according to claim 16,

wherein the nonmagnetic powder contained in the magnetic layer comprises inorganic powder with Mohs hardness of higher than 8.

19. The method of manufacturing a magnetic tape according to claim 16,

wherein the nonmagnetic powder contained in the magnetic layer comprises nonmagnetic colloidal particles.