MAGNETIC TAPE AND METHOD OF MANUFACTURING THE SAME

• US 20170053670A1
• 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: SUGIYAMA, Takuro, OYANAGI, Masahito, KASADA, Norihito, TADA, Toshio
• Granted Patent: US 10,026,434 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 5/70678 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 5/78 Tape carriers
• CPC Class Codes: G11B 5/842 Coating a support with a liquid magnetic dispersion

Abstract

The magnetic tape has a magnetic layer containing ferromagnetic powder and binder on a nonmagnetic support, wherein the centerline average surface roughness Ra as measured on the surface on the magnetic layer side of the magnetic tape is less than or equal to 1.8 nm, 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.

Claims

1. A magnetic tape,

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

wherein a centerline average surface roughness Ra as measured on a surface on the magnetic layer side of the magnetic tape is less than or equal to 1.8 nm, and

a 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.

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 centerline average surface roughness Ra is greater than or equal to 1.2 nm but less than or equal to 1.8 nm.

4. The magnetic tape according to claim 2,

wherein the centerline average surface roughness Ra is greater than or equal to 1.2 nm but less than or equal to 1.8 nm.

5. The magnetic tape according to claim 1,

wherein the magnetic layer comprises at least one type of nonmagnetic filler.

6. The magnetic tape according to claim 5,

wherein the nonmagnetic filler comprises colloidal particles.

7. The magnetic tape according to claim 1,

which comprises a nonmagnetic layer comprising nonmagnetic powder and binder between the nonmagnetic support and the magnetic layer.

8. A method of manufacturing a magnetic tape,

wherein the magnetic tape is a magnetic tape which comprises a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, wherein a centerline average surface roughness Ra as measured on a surface on the magnetic layer side of the magnetic tape is less than or equal to 1.8 nm, and a 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 method comprises forming a magnetic layer, with the forming of a magnetic layer comprising:

coating a magnetic layer-forming composition containing ferromagnetic powder, binder, a curing agent, and solvent on a nonmagnetic support, either directly or over another 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 atmosphere ranging from −

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 9,

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

12. 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.

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

wherein the thermosetting compound is polyisocyanate.

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

wherein surface-smoothing is conducted after the burnishing but before the curing.

15. 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.

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

wherein the centerline average surface roughness Ra is greater than or equal to 1.2 nm but less than or equal to 1.8 nm.

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

wherein the centerline average surface roughness Ra is greater than or equal to 1.2 nm but less than or equal to 1.8 nm.

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

wherein the magnetic layer comprises at least one type of nonmagnetic filler.

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

wherein the nonmagnetic filler comprises colloidal particles.

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

wherein the magnetic tape comprises a nonmagnetic layer comprising nonmagnetic powder and binder between the nonmagnetic support and the magnetic layer.