MAGNETIC TAPE, MAGNETIC TAPE CARTRIDGE, AND MAGNETIC RECORDING AND REPRODUCING DEVICE

• US 20170178677A1
• Filed: 12/15/2016
• Published: 06/22/2017
• Est. Priority Date: 12/16/2015
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: KASADA, Norihito
• Granted Patent: US 10,403,319 B2
• Time in Patent Office: Days
• 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

Abstract

The magnetic tape includes a nonmagnetic layer containing nonmagnetic powder and binder on a nonmagnetic support, and a magnetic layer containing ferromagnetic powder, abrasive, and binder on the nonmagnetic layer, wherein a thickness of the nonmagnetic layer is less than or equal to 0.50 μm, a coefficient of friction as measured on a base portion of a surface of the magnetic layer is less than or equal to 0.35, and ΔSFD in a longitudinal direction of the magnetic tape as calculated with Equation 1, ΔSFD=SFD_{25° C.}−SFD_{−190° C.}, is greater than or equal to 0.50, wherein, in Equation 1, SFD_{25° C.} denotes a SFD as measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25° C., and SFD_{−190° C.} denotes a SFD as measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −190° C.

Claims

1. A magnetic tape,

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

a thickness of the nonmagnetic layer is less than or equal to 0.50 μ

m;

a coefficient of friction as measured on a base portion of a surface of the magnetic layer is less than or equal to 0.35; and

Δ

SFD in a longitudinal direction of the magnetic tape as calculated with Equation 1 is greater than or equal to 0.50;

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Equation 1

wherein, in Equation 1, SFD<sub>25°

C.</sub> denotes a switching field distribution SFD as measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25°

C., and SFD<sub>−

190°

C.</sub> denotes a switching field distribution SFD as measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −

190°

C.

2. The magnetic tape according to claim 1,

wherein the abrasive comprises alumina.

3. The magnetic tape according to claim 1,

wherein the coefficient of friction as measured on the base portion of the surface of the magnetic layer is greater than or equal to 0.10 but less than or equal to 0.35.

4. The magnetic tape according to claim 1,

wherein the Δ

SFD is greater than or equal to 0.50 but less than or equal to 1.50.

5. The magnetic tape according to claim 1,

wherein a combined thickness of the magnetic layer and nonmagnetic layer is less than or equal to 0.60 μ

m.

6. The magnetic tape according to claim 1,

which comprises a backcoat layer comprising nonmagnetic powder and binder on an opposite side of the nonmagnetic support from a side on which the nonmagnetic layer and magnetic layer are present.

7. The magnetic tape according to claim 1,

wherein a total thickness of the magnetic tape is less than or equal to 6.00 μ

m.

8. 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.

9. A magnetic tape cartridge,

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

a thickness of the nonmagnetic layer is less than or equal to 0.50 μ

m;

a coefficient of friction as measured on a base portion of a surface of the magnetic layer is less than or equal to 0.35; and

Δ

SFD in a longitudinal direction of the magnetic tape as calculated with Equation 1 is greater than or equal to 0.50;

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Equation 1

wherein, in Equation 1, SFD<sub>25°

C.</sub> denotes a switching field distribution SFD as measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25°

C., and SFD<sub>−

190°

C.</sub> denotes a switching field distribution SFD as measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −

190°

C.

10. The magnetic tape cartridge according to claim 9,

wherein a total length of the magnetic tape that is housed in the magnetic tape cartridge is greater than or equal to 10 m.

11. The magnetic tape cartridge according to claim 9,

wherein the abrasive comprises alumina.

12. The magnetic tape cartridge according to claim 9,

wherein the coefficient of friction as measured on the base portion of the surface of the magnetic layer is greater than or equal to 0.10 but less than or equal to 0.35.

13. The magnetic tape cartridge according to claim 9,

wherein the Δ

SFD is greater than or equal to 0.50 but less than or equal to 1.50.

14. The magnetic tape cartridge according to claim 9,

wherein a combined thickness of the magnetic layer and nonmagnetic layer is less than or equal to 0.60 μ

m.

15. The magnetic tape cartridge according to claim 9,

wherein the magnetic tape comprises a backcoat layer comprising nonmagnetic powder and binder on an opposite side of the nonmagnetic support from a side on which the nonmagnetic layer and magnetic layer are present.

16. The magnetic tape cartridge according to claim 9,

wherein a total thickness of the magnetic tape is less than or equal to 6.00 μ

m.

17. The magnetic tape cartridge according to claim 9,

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

18. A magnetic recording and reproducing device,

which comprises a magnetic tape cartridge and a magnetic head,

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

a thickness of the nonmagnetic layer is less than or equal to 0.50 μ

m;

a coefficient of friction as measured on a base portion of a surface of the magnetic layer is less than or equal to 0.35; and

Δ

SFD in a longitudinal direction of the magnetic tape as calculated with Equation 1 is greater than or equal to 0.50;

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Equation 1

wherein, in Equation 1, SFD<sub>25°

C.</sub> denotes a switching field distribution SFD as measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25°

C., and SFD<sub>−

190°

C.</sub> denotes a switching field distribution SFD as measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −

190°

C.