Magnetic recording medium having a protective layer

Patent metadata

Field	Value
Publication number	US-10210892-B2
Application number	US-201615561397-A
Country	US
Kind code	B2
Filing date	Feb 8, 2016
Priority date	Mar 31, 2015
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

A magnetic recording medium includes a support, a recording layer, and a protective layer provided on at least one surface of the support and containing plate-shaped particle powder. The plate-shaped particle powder is stacked in an overlapping manner in a thickness direction of the protective layer such that main surfaces of plate-shaped particles face a surface of the support, and the plate-shaped particles have an average plate ratio of 60 or more.

First claim

The invention claimed is:

1. A magnetic recording medium comprising:
a support;
a recording layer; and
a protective layer provided on at least one surface of the support and containing plate-shaped particles, wherein
the plate-shaped particles are stacked on main surfaces of the plate-shaped particles in an overlapping manner in a thickness direction of the protective layer, and the main surfaces of the plate-shaped particles face a top surface of the support, and
the plate-shaped particles have an average plate ratio, and the average plate ratio of an average minimum diameter of the main surfaces of the plate-shaped particles to an average thickness of the plate-shaped particles is 60 or more.

2. The magnetic recording medium according to claim 1 , wherein the average plate ratio of the plate-shaped particles is 200 or more.

3. The magnetic recording medium according to claim 1 , wherein a ratio (Dm/Tm) of an average thickness Dm of the protective layer to an average plate thickness Tm of the plate-shaped particles is 30 or more.

4. The magnetic recording medium according to claim 1 , wherein the protective layer is provided on a surface opposite to the recording layer of both surfaces of the support.

5. The magnetic recording medium according to claim 1 , wherein the protective layer is provided on both surfaces of the support.

6. The magnetic recording medium according to claim 1 , wherein the plate-shaped particles include clay.

7. The magnetic recording medium according to claim 6 , wherein the clay is at least one selected from the group consisting of kaolinite, dickite, halloysite, chrysotile, lizardide, amesite, pyrophyllite, talc, montmorillonite, beidellite, nontronite, stevensite, saponite, hectorite, sauconite, dioctahedral vermiculite, trioctahedral vermiculite, muscovite, paragonite, illite, sericite, phlogopite, biotite, lepidolite, magadiite, irilite, and kanemite.

8. The magnetic recording medium according to claim 1 , wherein the plate-shaped particles include ferrite.

9. The magnetic recording medium according to claim 1 , further comprising a base layer provided under the recording layer.

10. The magnetic recording medium according to claim 1 , further comprising a back coat layer on an opposite side to the recording layer, wherein the back coat layer is provided on the protective layer.

Assignees

• Sony Corp

Inventors

• Nakashio Eiji
• Yamaga Minoru
• Takahashi Jun

Classifications

• G11B5/712

  characterised by the surface treatment or coating of magnetic particles · CPC title

• G11B5/70621

  containing Co metal or alloys · CPC title

• G11B5/70615

  containing Fe metal or alloys (G11B5/70621 takes precedence) · CPC title

• G11B5/735

  characterised by the back layer {(magnetic recording media substrates G11B5/739)} · CPC title

• H01F1/059

  and Va elements, e.g. Sm2Fe17N2 · CPC title