Magnetic tape

Patent metadata

Field	Value
Publication number	US-2016276076-A1
Application number	US-201615072550-A
Country	US
Kind code	A1
Filing date	Mar 17, 2016
Priority date	Mar 18, 2015
Publication date	Sep 22, 2016
Grant date	—

Abstract

The magnetic tape includes a magnetic layer containing ferromagnetic hexagonal ferrite powder, abrasive, and binder on a nonmagnetic support, wherein the ferromagnetic hexagonal ferrite powder exhibits an activation volume of less than or equal to 1,800 nm 3 , and inclination, cos θ, of the ferromagnetic hexagonal ferrite powder relative to a surface of the magnetic layer as determined by sectional observation by a scanning electron transmission microscope is greater than or equal to 0.85 but less than or equal to 1.00.

First claim

What is claimed is:

1 . A magnetic tape,
which comprises a magnetic layer comprising ferromagnetic hexagonal ferrite powder, abrasive, and binder on a nonmagnetic support, wherein the ferromagnetic hexagonal ferrite powder exhibits an activation volume of less than or equal to 1,800 nm 3 , and inclination, cos θ, of the ferromagnetic hexagonal ferrite powder relative to a surface of the magnetic layer as determined by sectional observation by a scanning electron transmission microscope is greater than or equal to 0.85 but less than or equal to 1.00.

2 . The magnetic tape according to claim 1 ,
wherein the abrasive comprises alumina.

3 . The magnetic tape according to claim 1 ,
which comprises a nonmagnetic layer comprising nonmagnetic powder and binder between the nonmagnetic support and the magnetic layer.

4 . The magnetic tape according to claim 1 ,
wherein the inclination, cos θ, is greater than or equal to 0.89 but less than or equal to 1.00.

5 . The magnetic tape according to claim 1 ,
wherein the ferromagnetic hexagonal ferrite powder exhibits an activation volume of greater than or equal to 800 nm 3 but less than or equal to 1,800 nm 3 .

6 . The magnetic tape according to claim 1 ,
wherein a centerline average surface roughness Ra that is measured with a noncontact surface profile measuring device is greater than or equal to 0.2 nm but less than or equal to 1.8 nm on the surface of the magnetic layer.

7 . The magnetic tape according to claim 1 ,
wherein the magnetic layer further comprises nonmagnetic colloidal particles.

8 . The magnetic tape according to claim 1 ,
wherein the magnetic layer further comprises a polyester chain-containing compound with a weight average molecular weight of greater than or equal to 1,000 but less than or equal to 80,000.

9 . The magnetic tape according to claim 8 ,
wherein the polyester chain-containing compound has a partial structure denoted by formula A below:

wherein, in formula A, Q denotes —O—, —CO—, —S—, —NR a —, or a single bond; each of T and R a independently denotes a hydrogen atom or a monovalent substituent; E denotes —(O-L A -CO)a- or —(CO-L A -O)a-; L A denotes a divalent connecting group; a denotes an integer of greater than or equal to 2; b denotes an integer of greater than or equal to 1; and * denotes a bond position with another partial structure constituting the polyester chain-containing compound.

10 . The magnetic tape according to claim 8 ,
wherein the polyester chain-containing compound comprises at least one group selected from the group consisting of a carboxyl group and a carboxyl salt.

11 . The magnetic tape according to claim 9 ,
wherein the polyester chain-containing compound comprises at least one group selected from the group consisting of a carboxyl group and a carboxyl salt.

12 . The magnetic tape according to claim 8 ,
wherein the polyester chain-containing compound comprises at least one polyalkyleneimine chain.

13 . The magnetic tape according to claim 9 ,
wherein the polyester chain-containing compound comprises at least one polyalkyleneimine chain.

14 . The magnetic tape according to claim 8 ,
wherein the magnetic layer comprises 0.5 to 25.0 weight parts of the polyester chain-containing compound per 100.0 weight parts of the ferromagnetic powder.

15 . The magnetic tape according to claim 9 ,
wherein the magnetic layer comprises 0.5 to 25.0 weight parts of the polyester chain-containing compound per 100.0 weight parts of the ferromagnetic powder.

16 . The magnetic tape according to claim 10 ,
wherein the magnetic layer comprises 0.5 to 25.0 weight parts of the polyester chain-containing compound per 100.0 weight parts of the ferromagnetic powder.

17 . The magnetic tape according to claim 11 ,
wherein the magnetic layer comprises 0.5 to 25.0 weight parts of the polyester chain-containing compound per 100.0 weight parts of the ferromagnetic powder.

18 . The magnetic tape according to claim 12 ,
wherein the magnetic layer comprises 0.5 to 25.0 weight parts of the polyester chain-containing compound per 100.0 weight parts of the ferromagnetic powder.

19 . The magnetic tape according to claim 13 ,
wherein the magnetic layer comprises 0.5 to 25.0 weight parts of the polyester chain-containing compound per 100.0 weight parts of the ferromagnetic powder.

Assignees

• Fujifilm Corp

Inventors

• Kasada Norihito

Classifications

• H01F1/113

  in a bonding agent · CPC title

• G11B5/7013

  characterised by the dispersing agent · CPC title

• G11B5/7085 Primary

  non-magnetic abrasive particles · CPC title

• G11B5/70678

  Ferrites · CPC title

• H01F1/11 Primary

  in the form of particles {(for magnetic record carriers G11B5/70626)} · CPC title