Magnetic tape having characterized coefficient of variation of e-iron oxide powder particle size, magnetic tape cartridge, and magnetic recording and reproducing apparatus

Patent metadata

Field	Value
Publication number	US-11670333-B2
Application number	US-202117199669-A
Country	US
Kind code	B2
Filing date	Mar 12, 2021
Priority date	Mar 13, 2020
Publication date	Jun 6, 2023
Grant date	Jun 6, 2023

Abstract

The magnetic tape includes a non-magnetic support and a magnetic layer including ferromagnetic powder, in which the ferromagnetic powder is ε-iron oxide powder, and a coefficient of variation of particle size of the ε-iron oxide powder in a longitudinal direction of the magnetic layer is 0.50% or more and 5.00% or less.

First claim

What is claimed is:

1. A magnetic tape comprising:
a non-magnetic support; and
a magnetic layer including ferromagnetic powder,
wherein the ferromagnetic powder is ε-iron oxide powder,
a coefficient of variation of particle size of the ε-iron oxide powder in a longitudinal direction of the magnetic layer is 0.55% or more and 5.00% or less, and
the coefficient of variation of particle size is determined according to the following expression by obtaining an average particle size d of ε-iron oxide powder at each of 50 locations at an interval of 10 cm in the longitudinal direction of the magnetic layer and then obtaining an arithmetic average dA and a standard deviation dD of values of the obtained 50 average particle sizes d's,
coefficient of variation of particle size=( dD/dA )×100.

2. The magnetic tape according to claim 1 , wherein the arithmetic average dA is 5.0 nm or more and 20.0 nm or less.

3. The magnetic tape according to claim 2 , wherein the coefficient of variation of particle size is 0.55% or more and 4.60% or less.

4. The magnetic tape according to claim 1 , wherein the arithmetic average dA is 5.0 nm or more and 15.0 nm or less.

5. The magnetic tape according to claim 4 , wherein the coefficient of variation of particle size is 0.55% or more and 4.60% or less.

6. The magnetic tape according to claim 1 , wherein the coefficient of variation of particle size is 0.55% or more and 4.60% or less.

7. The magnetic tape according to claim 1 , wherein the ε-iron oxide powder includes one or more elements selected from the group consisting of a gallium element, a cobalt element, and a titanium element.

8. The magnetic tape according to claim 1 , further comprising:
a non-magnetic layer including non-magnetic powder between the non-magnetic support and the magnetic layer.

9. The magnetic tape according to claim 1 , further comprising:
a back coating layer including non-magnetic powder on a surface side of the non-magnetic support opposite to a surface side having the magnetic layer.

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

11. The magnetic tape cartridge according to claim 10 , wherein the arithmetic average dA is 5.0 nm or more and 20.0 nm or less.

12. The magnetic tape cartridge according to claim 10 , wherein the arithmetic average dA is 5.0 nm or more and 15.0 nm or less.

13. The magnetic tape cartridge according to claim 10 , wherein the coefficient of variation of particle size is 0.55% or more and 4.60% or less.

14. The magnetic tape cartridge according to claim 10 , wherein the ε-iron oxide powder includes one or more elements selected from the group consisting of a gallium element, a cobalt element, and a titanium element.

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

16. The magnetic recording and reproducing apparatus according to claim 15 , wherein the arithmetic average dA is 5.0 nm or more and 20.0 nm or less.

17. The magnetic recording and reproducing apparatus according to claim 15 , wherein the arithmetic average dA is 5.0 nm or more and 15.0 nm or less.

18. The magnetic recording and reproducing apparatus according to claim 15 , wherein the coefficient of variation of particle size is 0.55% or more and 4.60% or less.

19. The magnetic recording and reproducing apparatus according to claim 15 , wherein the ε-iron oxide powder includes one or more elements selected from the group consisting of a gallium element, a cobalt element, and a titanium element.

Assignees

• Fujifilm Corp

Inventors

• Fujimoto Takashi
• Kasada Norihito
• Ozawa Eiki

Classifications

• G11B5/70642 Primary

  iron oxides · CPC title

• G11B5/714

  characterised by the dimension of the magnetic particles · CPC title

• G11B5/70673 Primary

  containing Co · CPC title