Magnetic tape and magnetic recording and reproducing device

Patent metadata

Field	Value
Publication number	US-10679657-B2
Application number	US-201916368271-A
Country	US
Kind code	B2
Filing date	Mar 28, 2019
Priority date	Mar 29, 2018
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

The magnetic tape includes a non-magnetic support; a magnetic layer including a ferromagnetic powder and a binding agent on one surface of the non-magnetic support; and a back coating layer including a non-magnetic powder and a binding agent on the other surface of the non-magnetic support, in which a center line average surface roughness Ra measured regarding a surface of the back coating layer is equal to or smaller than 7.0 nm, and a difference (Safter−Sbefore) between a spacing Safter measured by optical interferometry regarding the surface of the back coating layer after ethanol cleaning and a spacing Sbefore measured by optical interferometry regarding the surface of the back coating layer before ethanol cleaning is greater than 0 nm and equal to or smaller than 15.0 nm.

First claim

What is claimed is:

1. A magnetic tape comprising:
a non-magnetic support;
a magnetic layer including a ferromagnetic powder and a binding agent on one surface of the non-magnetic support; and
a back coating layer including a non-magnetic powder and a binding agent on the other surface of the non-magnetic support,
wherein the center line average surface roughness Ra measured regarding a surface of the back coating layer is equal to or smaller than 7.0 nm,
the difference (S after −S before ) between a spacing S after measured by optical interferometry regarding the surface of the back coating layer after ethanol cleaning and a spacing S before measured by optical interferometry regarding the surface of the back coating layer before ethanol cleaning is greater than 0 nm and equal to or smaller than 15.0 nm, and
the spacing measured by optical interferometry is measured by the following method:
overlapping a test piece of the magnetic tape on which ethanol cleaning has not been performed and a transparent plate-shaped member so that the surface of the back coating layer of the tape faces the transparent plate-shaped member;
pressing a pressing member against the side of the magnetic tape opposite to the back coating layer side at pressure of 5.05×10 4 N/m;
in this state, irradiating the surface of the back coating layer of the magnetic tape with light through the transparent plate-shaped member;
acquiring a spacing S before between the surface of the back coating layer of the magnetic tape and the surface of the transparent plate-shaped member on the magnetic tape based on intensity of interference light generated due to a difference in a light path between reflected light from the surface of the back coating layer of the magnetic tape and reflected light from the surface of the transparent plate-shaped member on the magnetic tape;
acquiring a spacing S after by the same method, employing a test piece of the magnetic tape on which ethanol cleaning has been performed; and
subtracting the results for the measurement of S before from the results for the measurement of S after to obtain the difference (S after −S before ).

2. The magnetic tape according to claim 1 ,
wherein the difference (S after −S before ) is 1.0 nm to 15.0 nm.

3. The magnetic tape according to claim 1 ,
wherein the difference (S after −S before ) is 2.0 nm to 13.0 nm.

4. The magnetic tape according to claim 1 , further comprising:
a non-magnetic layer including a non-magnetic powder and a binding agent between the non-magnetic support and the magnetic layer.

5. The magnetic tape according to claim 1 ,
wherein the center line average surface roughness Ra measured regarding the surface of the back coating layer is 3.0 nm to 7.0 nm.

6. A magnetic recording and reproducing device comprising:
a magnetic tape; and
a magnetic head,
wherein the magnetic tape is a magnetic tape comprising:

a non-magnetic support;
a magnetic layer including a ferromagnetic powder and a binding agent on one surface of the non-magnetic support; and
a back coating layer including a non-magnetic powder and a binding agent on the other surface of the non-magnetic support,
wherein the center line average surface roughness Ra measured regarding a surface of the back coating layer is equal to or smaller than 7.0 nm,
the difference (S after −S before ) between a spacing S after measured by optical interferometry regarding the surface of the back coating layer after ethanol cleaning and a spacing S before measured by optical interferometry regarding the surface of the back coating layer before ethanol cleaning is greater than 0 nm and equal to or smaller than 15.0 nm, and
the spacing measured by optical interferometry is measured by the following method:
overlapping a test piece of the magnetic tape on which ethanol cleaning has not been performed and a transparent plate-shaped member so that the surface of the back coating layer of the tape faces the transparent plate-shaped member;
pressing a pressing member against the side of the magnetic tape opposite to the back coating layer side at pressure of 5.05×10 4 N/m;
in this state, irradiating the surface of the back coating layer of the magnetic tape with light through the transparent plate-shaped member;
acquiring a spacing S before between the surface of the back coating layer of the magnetic tape and the surface of the transparent plate-shaped member on the magnetic tape based on intensity of interference light generated due to a difference in a light path between reflected light from the surface of the back coating layer of the magnetic tape and reflected light from the surface of the transparent plate-shaped member on the magnetic tape;
acquiring a spacing S after by the same method, employing a test piece of the magnetic tape on which ethanol cleaning has been performed; and
subtracting the results for the measurement of S before from the results for the measurement of S after to obtain the difference (S after −S before ).

7. The magnetic recording and reproducing device according to claim 6 ,
wherein the difference (S after −S before ) is 1.0 nm to 15.0 nm.

8. The magnetic recording and reproducing device according to claim 6 ,
wherein the difference (S after −S before ) is 2.0 nm to 13.0 nm.

9. The magnetic recording and reproducing device according to claim 6 ,
wherein the magnetic tape further comprises a non-magnetic layer including a non-magnetic powder and a binding agent between the non-magnetic support and the magnetic layer.

10. The magnetic recording and reproducing device according to claim 6 ,
wherein the center line average surface roughness Ra measured regarding the surface of the back coating layer is 3.0 nm to 7.0 nm.

Assignees

• Fujifilm Corp

Inventors

• Kurokawa Takuto
• Ozawa Eiki

Classifications

• G11B5/127

  Structure or manufacture of heads, e.g. inductive · CPC title

• G11B5/712

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

• G11B5/78

  Tape carriers · CPC title

• G11B5/70684 Primary

  Ferro-ferrioxydes · CPC title

• G11B5/70 Primary

  on a base layer · CPC title