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-11017808-B2
Application number	US-201615765416-A
Country	US
Kind code	B2
Filing date	Oct 27, 2016
Priority date	Nov 12, 2015
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

A fractionation method for magnetic recording-magnetic powder is provided. The method includes applying a magnetic field to a liquid that contains magnetic recording-magnetic powder dispersed therein, wherein the liquid is stored in a storage unit relatively shifting a position where the magnetic field is applied to the liquid; and separating the storage unit into two parts after the shift.

First claim

The invention claimed is:

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, wherein the liquid is stored in a storage unit;
relatively shifting a position where the magnetic field is applied to the liquid; and
separating the storage unit into two parts after the shift.

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

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

5. 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.

6. 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.

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

8. The fractionation method for magnetic recording-magnetic powder according to claim 7 , 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.

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

10. 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, 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;
separating the first chamber and the second chamber after the shift; and
extracting a liquid in the second chamber.

Assignees

• Sony Corp

Inventors

• Katori Kenji

Classifications

• G11B5/845 Primary

  in a magnetic field · 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

• G11B5/842

  Coating a support with a liquid magnetic dispersion · CPC title

• G11B5/714 Primary

  characterised by the dimension of the magnetic particles · CPC title