Magnetic tape having controlled water contact angle ratio, magnetic tape cartridge, and magnetic tape apparatus

Patent metadata

Field	Value
Publication number	US-11869559-B2
Application number	US-202217873728-A
Country	US
Kind code	B2
Filing date	Jul 26, 2022
Priority date	Jul 27, 2021
Publication date	Jan 9, 2024
Grant date	Jan 9, 2024

Abstract

The magnetic tape includes a non-magnetic support, and a magnetic layer including a ferromagnetic powder. A fluorine-containing compound is included in a portion on the non-magnetic support on a magnetic layer side, and a ratio θr of a water contact angle measured on a surface of the magnetic layer after sliding on a magnetic head to a water contact angle measured on the surface of the magnetic layer before sliding on the magnetic head is 0.70 or more.

First claim

What is claimed is:

1. A magnetic tape comprising:
a non-magnetic support; and
a magnetic layer including a ferromagnetic powder,
wherein a fluorine-containing compound is included in a portion on the non-magnetic support on a magnetic layer side, and
a ratio θr of a water contact angle (θ after ) measured on a surface of the magnetic layer after sliding on a magnetic head to a water contact angle (θ before ) measured on the surface of the magnetic layer before sliding on the magnetic head is 0.70 or more,
wherein the water contact angle is measured as follows:
a tape sample having any length enough to measure the water contact angle and a tape sample having a length of 100 m are cut out from any position in the longitudinal direction of the same magnetic tape; for the tape sample having any length, a water contact angle θ before is obtained without sliding on the magnetic head; for the tape sample having a length of 100 m, a water contact angle θ after is obtained after sliding on the magnetic head; the sliding between the magnetic tape and the magnetic head is performed by a reel tester at a running speed of 4 m/sec and a tension applied in longitudinal direction of the magnetic tape of 100 gf, in an environment of an atmosphere temperature of 23° C.±1° C. and a relative humidity of 50%; the water contact angle is an arithmetic average of values obtained by measuring the tape sample to be measured at six different locations of the magnetic layer surface by a θ/2 method in a measurement environment of an atmosphere temperature of 25° C. and a relative humidity of 50%, and
the fluorine-containing compound is one or more fluorine-containing polymers, the fluorine-containing polymer being a polymer having a branched structure that includes a repeating unit represented by General Formula (1) and at least one repeating unit selected from the group consisting of a repeating unit represented by General Formula (2) and a repeating unit represented by General Formula (3):

in General Formula (1),
R 1 and R 2 each independently represent a hydrogen atom or a methyl group,
L 1 and L 2 each independently represent a divalent linking group,
Rf 1 , Rf 2 , Rf 3 , and Rf 4 each independently represent a fluorine atom or a perfluoroalkyl group,
u represents an integer of 1 or more,
p represents an integer of 2 or more,
t represents an integer of 0 or more,
a plurality of Rf 1 's may be the same as or different from each other,
a plurality of Rf 2 's may be the same as or different from each other,
in a case where there are a plurality of Rf 3 's, the plurality of Rf 3 's may be the same as or different from each other,
in a case where there are a plurality of Rf 4 's, the plurality of Rf 4 's may be the same as or different from each other,

in General Formula (2),
R 3 represents a hydrogen atom or a methyl group,
L 3 represents a single bond or a divalent linking group,
X 1 represents —OH, —COOH, —PO 3 H, {—OP(═O)(OH) 2 }, —OM 1 , —CO 2 M 1 , —SO 3 M 1 , —NT 1 T 2 , an epoxy group, an alicyclic epoxy group, an oxazoline group, —NG 1 G 2 G 3 E 1 , or a group having a betaine structure,
M 1 represents alkali metal, alkaline earth metal, Mg, Al, or Q 1 Q 2 Q 3 Q 4 N + ,
Q 1 , Q 2 , Q 3 , and Q 4 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms,
T 1 and T 2 each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms,
T 1 and T 2 may be bonded,
E 1 represents an anion,
G 1 , G 2 , and G 3 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atom,

in General Formula (3),
R 4 represents a hydrogen atom, a fluorine atom, a chlorine atom, or an alkyl group having 1 to 20 carbon atoms,
U 1 and U 2 each independently represent —O—, —S—, —COO—, —OCO—, —CONH—, —NHCOO—, or NH—
R 5 and R 6 each independently represent a hydrogen atom, an aliphatic hydrocarbon group, an aryl group, or a heteroaryl group,
R 5 and R 6 may be bonded,
L 4 represents a single bond or a divalent linking group.

2. The magnetic tape according to claim 1 ,
wherein the ratio θr is 0.80 or more.

3. The magnetic tape according to claim 1 ,
wherein the ratio θr is 0.85 or more.

4. The magnetic tape according to claim 1 , further comprising:
one or more non-magnetic layers including a non-magnetic powder between the non-magnetic support and the magnetic layer.

5. The magnetic tape according to claim 1 , further comprising:
a back coating layer including a non-magnetic powder on a surface side of the non-magnetic support opposite to a surface side having the magnetic layer,
wherein the fluorine-containing compound is selected from the group consisting of polymers (1-1) to (1-21), and for each polymer, “a” and “b” represent a content (unit: mass %) of each repeating unit with respect to the total repeating unit in the polymer:

6. The magnetic tape according to claim 1 ,
wherein the ferromagnetic powder is a hexagonal strontium ferrite powder.

7. The magnetic tape according to claim 1 ,
wherein the ferromagnetic powder is a hexagonal barium ferrite powder.

8. The magnetic tape according to claim 1 ,
wherein the ferromagnetic powder is an ε-iron oxide powder.

9. A magnetic tape cartridge comprising:
the magnetic tape according to claim 1 .

10. The magnetic tape cartridge according to claim 9 ,
wherein the ratio θr is 0.80 or more.

11. The magnetic tape cartridge according to claim 9 ,
wherein the ratio θr is 0.85 or more.

12. The magnetic tape cartridge according to claim 9 ,
wherein the ferromagnetic powder is a hexagonal strontium ferrite powder.

13. The magnetic tape cartridge according to claim 9 ,
wherein the ferromagnetic powder is a hexagonal barium ferrite powder.

14. The magnetic tape cartridge according to claim 9 ,
wherein the ferromagnetic powder is an ε-iron oxide powder.

15. A magnetic tape apparatus comprising:
the magnetic tape according to claim 1 .

16. The magnetic tape apparatus according to claim 15 ,
wherein the ratio θr is 0.80 or more.

17. The magnetic tape apparatus according to claim 15 ,
wherein the ratio θr is 0.85 or more.

18. The magnetic tape apparatus according to claim 15 ,
wherein the ferromagnetic powder is a hexagonal strontium ferrite powder.

19. The magnetic tape apparatus according to claim 15 ,
wherein the ferromagnetic powder is a hexagonal barium ferrite powder.

20. The magnetic tape apparatus according to claim 15 ,
wherein the ferromagnetic powder is an ε-iron oxide powder.

Assignees

• Fujifilm Corp

Inventors

• Oyanagi Noriko
• Kikuchi Wataru
• Tamura Akio

Classifications

• G11B5/78 Primary

  Tape carriers · CPC title

• G11B5/7028 Primary

  Additives, e.g. crosslinking agents · CPC title

• G11B5/70678

  Ferrites · CPC title

• G11B5/71

  characterised by the lubricant · CPC title

• G11B5/714

  characterised by the dimension of the magnetic particles · CPC title