Magnetic tape

Patent metadata

Field	Value
Publication number	US-10614834-B2
Application number	US-201715716622-A
Country	US
Kind code	B2
Filing date	Sep 27, 2017
Priority date	Sep 30, 2016
Publication date	Apr 7, 2020
Grant date	Apr 7, 2020

Abstract

Provided is a magnetic tape in which a vertical direction squareness ratio and/or a longitudinal direction squareness ratio obtained by measurement performed by sweeping an external magnetic field in the magnetic tape in a predetermined range by a vibrating sample magnetometer is 0.70 to 1.00, and A calculated by Expression 1 is equal to or smaller than 5.0%. In Expression 1, n represents the number of measurement points measured at magnetic field strength of −40 kA/m to 40 kA/m during the sweeping and is 52, Mr(Hex) represents a magnetization quantity measured at magnetic field strength Hex, and μ represents an arithmetical mean of Mr(Hex) obtained by measurement performed in the range of the magnetic field strength during the sweeping.

A
=

100
×

1

n
-
1

⁢

∑

Hex
=

-
40

⁢

kA
/
m

∼

40
⁢

⁢

kA
/
m

⁢

⁢

(

Mr
⁡

(
Hex
)

-
μ

)

2

/
μ

Expression
⁢

⁢
1

First claim

What is claimed is:

1. A magnetic tape comprising:
a non-magnetic support; and
a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support,
wherein the ferromagnetic powder is ferromagnetic hexagonal ferrite powder,
a vertical direction squareness ratio obtained without diamagnetic field correction by measurement performed by sweeping an external magnetic field in the magnetic tape at magnetic field strength of −1197 kA/m to 1197 kA/m by a vibrating sample magnetometer is 0.70 to 1.00, and
A calculated by Expression 1 is equal to or smaller than 5.0%;

A
=

100
×

1

n
-
1

⁢

∑

Hex
=

-
40

⁢

kA
/
m

∼

40
⁢

⁢

kA
/
m

⁢

⁢

(

M
⁢

⁢

r
⁡

(

H
⁢

⁢
e
⁢

⁢
x

)

-
μ

)

2

/
μ

Expression
⁢

⁢
1

in Expression 1, n represents the number of measurement points measured at magnetic field strength of −40 kA/m to 40 kA/m during the sweeping and is 52, Mr(Hex) represents a magnetization quantity measured at magnetic field strength Hex, and μ represents an arithmetical mean of Mr(Hex) obtained by measurement performed at magnetic field strength of −40 kA/m to 40 kA/m during the sweeping.

2. The magnetic tape according to claim 1 ,
wherein the A is 1.5% to 5.0%.

3. The magnetic tape according to claim 1 ,
wherein the A is 1.5% to 3.9%.

4. The magnetic tape according to claim 1 ,
wherein the vertical direction squareness ratio obtained by the measurement is 0.75 to 1.00.

5. The magnetic tape according to claim 2 ,
wherein the vertical direction squareness ratio obtained by the measurement is 0.75 to 1.00.

6. The magnetic tape according to claim 3 ,
wherein the vertical direction squareness ratio obtained by the measurement is 0.75 to 1.00.

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

8. The magnetic tape according to claim 1 , further comprising:
a back coating layer, including non-magnetic powder and a binding agent, on a surface side of the non-magnetic support opposite to a surface side provided with the magnetic layer.

Assignees

• Fujifilm Corp

Inventors

• Morooka Atsushi
• Tada Toshio

Classifications

• G11B5/00813 Primary

  magnetic tapes · CPC title

• G11B5/70678

  Ferrites · CPC title

• G11B5/78

  Tape carriers · CPC title

• G11B5/70 Primary

  on a base layer · CPC title