Magnetic recording medium

• US 6,268,043 B1
• Filed: 02/16/2000
• Issued: 07/31/2001
• Est. Priority Date: 02/23/1999
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sato, Miwako, Adachi, Norio, Koizumi, Takeshi
• Primary Examiner(s): Resan, Stevan A.
• Application Number:
  US09/505,187
• Time in Patent Office: 531 Days
• Field of Search: 428/212, 428/216, 428/694.BM, 428/900, 428/323, 428/336
• US Class Current: 428/212
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/716 characterised by two or more magnetic layers
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

A magnetic recording medium which is capable of improving durability and reliability while satisfactory electromagnetic conversion characteristics are being maintained, the magnetic recording medium incorporating a non-magnetic support member; and a magnetic layer formed on the non-magnetic support member and mainly composed of magnetic powder and a binder and having a two-layer structure composed of a first magnetic layer and a second magnetic layer, wherein Young'"'"'s modulus of the first magnetic layer is 140×10⁵ N/m² to 160×10⁵ N/m² and Young'"'"'s modulus of the second magnetic layer is 45×10⁵ N/m² to 50×10⁵ N/m². The specific surface area of the magnetic powder for use in the first magnetic layer is 42 m²/g to 46 m²/g and the specific surface area of the magnetic powder for use in the second magnetic layer is 32 m²/g to 35 m²/g.

Claims

1. A magnetic recording medium comprising:

a non-magnetic support member; and

a magnetic layer formed on said non-magnetic support member and mainly composed of magnetic powder and a binder and having a two-layer structure composed of a first magnetic layer and a second magnetic layer, wherein

Young'"'"'s modulus of said first magnetic layer is 140×

10⁵ N/m² to 160×

10⁵ N/m² and

Young'"'"'s modulus of said second magnetic layer is 45×

10⁵ N/m² to 50×

10⁵ N/m².

2. A magnetic recording medium according to claim 1, where the specific surface area of the magnetic powder for use in said first magnetic layer is 42 mn²/g to 46 m²/g and the specific surface area of the magnetic powder for use in said second magnetic layer is 32 m²/g to 35 m²/g.

3. A magnetic recording medium according to claim 1, wherein the thickness of said first magnetic layer is 1.0 μ

m to 2.5 μ

m and the thickness of said second magnetic layer is 2.0 μ

m to 4.0 μ

m.