Fractionation method for magnetic recording-magnetic powder, fractionation apparatus for magnetic recording-magnetic powder, and method of producing magnetic recording medium

Patent metadata

Field	Value
Publication number	US-2018308516-A1
Application number	US-201615765416-A
Country	US
Kind code	A1
Filing date	Oct 27, 2016
Priority date	Nov 12, 2015
Publication date	Oct 25, 2018
Grant date	—

Abstract

A fractionation method for magnetic recording-magnetic powder includes: applying a magnetic field to a liquid that contains magnetic recording-magnetic powder dispersed therein; and relatively shifting a position where the magnetic field is applied to the liquid.

First claim

1 . A fractionation method for magnetic recording-magnetic powder, the method comprising:
applying a magnetic field to a liquid that contains magnetic recording-magnetic powder dispersed therein; and relatively shifting a position where the magnetic field is applied to the liquid.

2 . The fractionation method for magnetic recording-magnetic powder according to claim 1 , the method further comprising extracting part of the liquid that remains at the position after the shift where the magnetic field is applied.

3 . The fractionation method for magnetic recording-magnetic powder according to claim 2 , the method further comprising:
separating part of the liquid so that the part includes the liquid at the position after the shift where the magnetic field is applied; and extracting part of the liquid after the separation.

4 . The fractionation method for magnetic recording-magnetic powder according to claim 1 ,
wherein the liquid is stored in a storage unit including at least a first chamber and a second chamber, and the shift of the position where the magnetic field is applied is a shift from the first chamber to the second chamber.

5 . The fractionation method for magnetic recording-magnetic powder according to claim 4 , the method further comprising:
separating the first chamber and the second chamber after the shift; and extracting a liquid in the second chamber.

6 . The fractionation method for magnetic recording-magnetic powder according to claim 1 ,
wherein the liquid is stored in a storage unit, and the shift is a shift from one end to another end of the storage unit.

7 . The fractionation method for magnetic recording-magnetic powder according to claim 1 , wherein the magnetic field is applied by a magnetic field application unit held obliquely with respect to a direction of the shift.

8 . The fractionation method for magnetic recording-magnetic powder according to claim 1 , wherein the magnetic field at a time of the shift is equal to or higher than an external magnetic field worth of 1/20 of coercive force Hc of the magnetic recording-magnetic powder and equal to or lower than an external magnetic field worth of coercive force Hc of the magnetic recording-magnetic powder.

9 . The fractionation method for magnetic recording-magnetic powder according to claim 1 , wherein the magnetic field is an AC magnetic field.

10 . The fractionation method for magnetic recording-magnetic powder according to claim 9 , wherein the AC magnetic field at a time of the shift has a frequency of 0.1 Hz or more and 100 Hz or less.

11 . The fractionation method for magnetic recording-magnetic powder according to claim 1 , wherein the magnetic recording-magnetic powder is hexagonal ferrite magnetic powder.

12 . A fractionation apparatus for magnetic recording-magnetic powder, the apparatus comprising:
a storage unit configured to store a liquid that contains magnetic recording-magnetic powder dispersed therein; a magnetic field application unit configured to apply a magnetic field to the liquid; and a shifting unit configured to shift at least one of the storage unit and the magnetic field application unit so as to relatively shift a position where the magnetic field is applied to the liquid.

13 . A fractionation apparatus for magnetic recording-magnetic powder, the apparatus comprising:
a magnetic field application unit configured to apply a magnetic field to a liquid that is stored in a storage unit and that contains magnetic recording-magnetic powder dispersed therein; and a shifting unit configured to shift at least one of the storage unit and the magnetic field application unit so as to relatively shift a position where the magnetic field is applied to the liquid.

14 . The fractionation apparatus for magnetic recording-magnetic powder according to claim 12 ,
wherein the storage unit is configured to be separable at a part of the storage unit, and the shifting unit is configured to shift the position where the magnetic field is applied from an outer side of the part of the storage unit to the part of the storage unit.

15 . The fractionation apparatus for magnetic recording-magnetic powder according to claim 14 , the apparatus further comprising a discharging unit configured to discharge a dispersion liquid in the part of the storage unit.

16 . The fractionation apparatus for magnetic recording-magnetic powder according to claim 12 ,
wherein the storage unit includes at least a first chamber and a second chamber, and the shifting unit is configured to shift the position where the magnetic field is applied from the first chamber to the second chamber.

17 . The fractionation apparatus for magnetic recording-magnetic powder according to claim 13 , wherein the magnetic field application unit is held obliquely with respect to a direction of the shift, so that the position where the magnetic field is applied shifts from one end to another end of the storage unit along with the shift.

18 . The fractionation apparatus for magnetic recording-magnetic powder according to claim 12 , wherein the storage unit has a cuboid shape or a cylindrical shape.

19 . A method of producing a magnetic recording medium, the method comprising:
applying a magnetic field to a liquid that contains magnetic recording-magnetic powder dispersed therein; relatively shifting a position where the magnetic field is applied to the liquid; extracting part of the liquid that remains at the position after the shift where the magnetic field is applied; and forming a magnetic layer using the magnetic recording-magnetic powder contained in the extracted liquid.

Assignees

• Sony Corp

Inventors

• Katori Kenji

Classifications

• G11B5/842

  Coating a support with a liquid magnetic dispersion · CPC title

• G11B5/714 Primary

  characterised by the dimension of the magnetic particles · CPC title

• G11B5/73

  Base layers {, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer} · CPC title

• H01F41/16

  the magnetic material being applied in the form of particles, e.g. by serigraphy {, to form thick magnetic films or precursors therefor} (H01F41/18 {-H01F41/24} take precedence) · CPC title

• G11B5/70678

  Ferrites · CPC title