US 12,394,437 B2
Magnetic tape, magnetic tape cartridge, and magnetic tape device
Shinji Tsujimoto, Minamiashigara (JP); Shunichi Hoshino, Minamiashigara (JP); and Yoshihiro Sawayashiki, Minamiashigara (JP)
Assigned to FUJIFILM Corporation, Tokyo (JP)
Filed by FUJIFILM Corporation, Tokyo (JP)
Filed on Jan. 30, 2023, as Appl. No. 18/161,509.
Application 18/161,509 is a continuation of application No. PCT/JP2021/028014, filed on Jul. 29, 2021.
Claims priority of application No. 2020-130865 (JP), filed on Jul. 31, 2020.
Prior Publication US 2023/0178107 A1, Jun. 8, 2023
Int. Cl. G11B 5/735 (2006.01); G11B 5/78 (2006.01)
CPC G11B 5/7353 (2019.05) [G11B 5/78 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A magnetic tape comprising:
a non-magnetic support;
a magnetic layer containing alumina, carbon black, and a ferromagnetic powder being at least one selected from the group consisting of hexagonal barium ferrite powder, hexagonal strontium ferrite powder and s-iron oxide powder; and
a non-magnetic layer containing a non-magnetic powder between the non-magnetic support and the magnetic layer,
wherein the magnetic layer and/or non-magnetic layer comprise at least one selected from the group consisting of a fatty acid and a fatty acid amide;
the magnetic layer and/or non-magnetic layer comprise a fatty acid ester;
an amount of a fluid lubricant, which is an amount of said fatty acid ester, collected by wiping a surface of the magnetic layer with a nonwoven fabric is in a range of 8 to 389 ng/m2 as a value per unit area of the surface of the magnetic layer;
the nonwoven fabric is a mixture of rayon/polyester/nylon and satisfies the following conditions:
weight: 40±5 g/m2,
thickness: 0.27±0.05 μm,
width: 25 mm, and
average fiber diameter: 10±5 μm;
the amount of fluid lubricant is obtained by a method employing a reel tester having two tape reels, at 23° C. and a relative humidity of 50%, in which the magnetic tape is caused to run on the reel tester to bring the surface of the tape's magnetic layer into contact with the nonwoven fabric and wipe the surface with the nonwoven fabric, the running conditions of the magnetic tape being as follows:
running speed of magnetic tape: 2 m/sec,
tension applied in the longitudinal direction of the magnetic tape: 100 gf,
running length of magnetic tape: 200 m,
running pass of magnetic tape: 1 single pass, and
lap angle θ:25°; and
the amount of fluid lubricant collected by wiping the surface of the magnetic layer is determined, after wiping the surface of the magnetic layer, by cutting out a piece of fabric having a length of 60 mm from the nonwoven fabric, said piece of fabric including a portion which was in contact with the magnetic tape at the time of wiping, extracting components from said piece of fabric with a solvent, and analyzing the extract.