MAGNETIC RECORDING MEDIUM

• US 20160180875A1
• Filed: 02/26/2016
• Published: 06/23/2016
• Est. Priority Date: 08/17/2010
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Hitachi Maxell Limited (Hitachi, Ltd.)
• Inventors: TANAKA, Kenji, FUJITA, Masao, KUSE, Sadamu
• Granted Patent: US 9,767,835 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 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. 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 is either a platy hexagonal ferrite magnetic powder or a spherical iron nitride magnetic powder,

the magnetic layer has a thickness of 10 to 150 nm,

the magnetic layer has a surface roughness of 1 nm or more and less than 2 nm, and

when spacing of the surface of the magnetic layer before and after washing the magnetic recording medium with n-hexane is measured with a TSA (Tape Spacing Analyzer) while pressurizing the surface of the magnetic recording medium under a pressing pressure of 0.5 atm, 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 value of the spacing after washing is between 5 nm and 10 nm.

3. The magnetic recording medium according to claim 1,

wherein the magnetic powder has an average particle size between 15 nm and 35 nm.