MAGNETIC RECORDING MEDIUM

• US 20120045664A1
• Filed: 08/16/2011
• Published: 02/23/2012
• Est. Priority Date: 08/17/2010
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Hitachi Maxell Limited (Maxell, Ltd.)
• Inventors: TANAKA, Kenji, Fujita, Masao, Kuse, Sadamu
• Granted Patent: US 9,311,946 B2
• Time in Patent Office: Days
• US Class Current: 428/840.2
• CPC Class Codes: G11B 5/70615 containing Fe metal or alloys G11B5/70621 takes precedence
• CPC Class Codes: G11B 5/70626 containing non-metallic substances
• CPC Class Codes: G11B 5/71 characterised by the lubricant
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles
• CPC Class Codes: G11B 5/733 characterised by the addition of non-magnetic particles base layers having a non-magnetic layer under a soft magnetic layer G11B5/736; magnetic recording media substrates G11B5/739
• CPC Class Codes: G11B 5/7356 comprising non-magnetic particles in the back layer, e.g. particles of TiO2, ZnO or SiO2
• CPC Class Codes: G11B 5/78 Tape carriers

Abstract

A magnetic recording medium of the present invention is a magnetic recording medium including a non-magnetic substrate; a non-magnetic layer that is formed on one of principal surfaces of the non-magnetic substrate and contains a non-magnetic powder, a binder, and a lubricant; and a magnetic layer that is formed on a principal surface of the non-magnetic layer opposite to the non-magnetic substrate and contains a magnetic powder and a binder. The magnetic powder has an average particle size between 10 inn and 35 nm inclusive. The lubricant is migratable to the magnetic layer and forms a lubricant layer on a surface of the magnetic layer when a pressure is applied to the magnetic layer. When spacing of the surface of the magnetic layer before and after washing the lubricant with n-hexane is measured with a TSA (Tape Spacing Analyzer), the value of the spacing after washing is 3 to 10 nm, and the value of the spacing before washing is 1 to 5 nm smaller than the value of the spacing after washing.

Claims

1. A magnetic recording medium comprising a non-magnetic substrate;

a non-magnetic layer that is formed on one of principal surfaces of the non-magnetic substrate and contains a non-magnetic powder, a binder, and a lubricant; and

a magnetic layer that is formed on a principal surface of the non-magnetic layer opposite to the non-magnetic substrate and contains a magnetic powder and a binder,

wherein the magnetic powder has an average particle size between 10 nm and 35 nm inclusive,

the lubricant is migratable to the magnetic layer and forms a lubricant layer on a surface of the magnetic layer when a pressure is applied to the magnetic layer, and

when spacing of the surface of the magnetic layer before and after washing the lubricant with n-hexane is measured with a TSA (Tape Spacing Analyzer), the value of the spacing after washing is 3 to 10 nm, and the value of the spacing before washing is 1 to 5 nm smaller than the value of the spacing after washing.

2. The magnetic recording medium according to claim 1, wherein the magnetic layer has a surface roughness of 1 nm or more and less than 2 nm.

3. The magnetic recording medium according to claim 1,

wherein the TSA disposes a transparent body in contact with and opposing the surface of the magnetic layer, irradiates the transparent body side of the magnetic layer with light through the transparent body, and calculates spacing between the magnetic layer and the transparent body based on an intensity of coherent light that is generated in a portion where the surface of the magnetic layer and the transparent body are opposing each other.

4. The magnetic recording medium according to claim 1, wherein the non-magnetic powder contained in the non-magnetic layer has an average particle size of 10 to 1000 nm.

5. The magnetic recording medium according to claim 1, wherein the lubricant contained in the non-magnetic layer comprises a fatty acid having 10 to 30 carbon atoms.

6. The magnetic recording medium according to claim 5, wherein the fatty acid comprises at least one selected from a group consisting of lauric acid, myristic acid, stearic acid, palmitic acid, behenic acid, oleic acid, and linoleic acid.

7. The magnetic recording medium according to claim 5, wherein the content of the fatty acid in the non-magnetic layer is 0.2 to 5 parts by mass with respect to 100 parts by mass of the non-magnetic powder.

8. The magnetic recording medium according to claim 5, wherein the lubricant contained in the non-magnetic layer further comprises at least one of a fatty acid ester and a fatty acid amide.

9. The magnetic recording medium according to claim 8, wherein the combined content of the fatty acid ester and the fatty acid amide in the non-magnetic layer is 0.2 to 10 parts by mass with respect to 100 parts by mass of the non-magnetic powder.

10. The magnetic recording medium according to claim 1, wherein the non-magnetic layer has a thickness of 0.1 to 3 μ

m.

11. The magnetic recording medium according to claim 1, wherein the magnetic layer further contains, as a lubricant, 0.2 to 3 parts by mass of a fatty acid ester with respect to a total amount of all the powders in the magnetic layer and 0.5 to 5 parts by mass of a fatty acid amide with respect to the total amount of all the powders in the magnetic layer.

12. The magnetic recording medium according to claim 1, wherein the magnetic layer has a thickness of 10 to 150 nm.

13. The magnetic recording medium according to claim 1, wherein the non-magnetic substrate has a thickness of 1.5 to 11 μ

m.

14. The magnetic recording medium according to claim 1, further comprising a backcoat layer that is formed on the principal surface of the non-magnetic substrate opposite to the non-magnetic layer.