Magnetic recording medium and method for manufacturing same

• US 20020136929A1
• Filed: 11/08/2001
• Published: 09/26/2002
• Est. Priority Date: 11/09/2000
• Status: Abandoned Application

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Shimizu, Takahiro, Uwazumi, Hiroyuki, Takizawa, Naoki, Oikawa, Tadaaki
• Application Number:
  US10/008,743
• Publication Number:
  US 20020136929A1
• Time in Patent Office: Days
• US Class Current: 428/694TM
• CPC Class Codes: G11B 5/66 the record carriers consisting of several layers
• CPC Class Codes: G11B 5/678 having three or more magnetic layers
• CPC Class Codes: G11B 5/84 Processes or apparatus specially adapted for manufacturing record carriers
• CPC Class Codes: Y10T 428/1259 Oxide
• CPC Class Codes: Y10T 428/12611 Oxide-containing component
• CPC Class Codes: Y10T 428/12861 Group VIII or IB metal-base component
• CPC Class Codes: Y10T 428/12868 Group IB metal-base component alternative to platinum group metal-base component [e.g., precious metal, etc.]

Abstract

A magnetic recording medium has a non-magnetic under-layer, a magnetic layer, a protective film and a liquid lubricant layer sequentially laminated on a non-magnetic substrate. The magnetic layer has a multi-layer structure laminated with two or more magnetic layer components, each of the magnetic layer components having ferromagnetic grains and non-magnetic grain boundaries surrounding the grain. The resulting magnetic recording medium has a granular magnetic layer exhibiting very high Hc accompanying high density of magnetic recording, while decreasing the amount of platinum needed for attaining the high Hc, and reducing media noise accompanying the high recording density.

Claims

1. A magnetic recording medium comprising:

a non-magneticmagnetic under-layer, a magnetic layer, a protective film, and a liquid lubricant layer sequentially laminated on a non-magneticmagnetic substrate, wherein

said magnetic layer has a layered structure including at least two magnetic layer components, each of said magnetic layer components having ferromagnetic grains and non-magneticmagnetic grain boundaries surrounding said ferromagnetic grains.

2. The magnetic recording medium according to claim 1, wherein said at least two magnetic layer components have a composition different from one another.

3. The magnetic recording medium according to claim 1, wherein said non-magneticmagnetic grain boundaries are composed of an oxide or a nitride of at least one element selected from the group consisting of Cr, Co, Si, Al, Ti, Ta, Hf and Zr.

4. The magnetic recording medium according to claim 1, wherein said under-layer is composed of chromium or chromium alloy.

5. The magnetic recording medium according to claim 1, wherein said substrate is composed of one of a crystallized glass, a chemically strengthened glass and a plastic.

6. A magnetic recording medium comprising:

a non-magneticmagnetic under-layer, a magnetic layer, a protective film, and a liquid lubricant layer sequentially laminated on a non-magneticmagnetic substrate, wherein

said magnetic layer includes at least two magnetic layer components and at least three oxide layers; and

said magnetic layer components and said oxide layers are alternately disposed such that a top layer and a bottom layer in said magnetic layer are two of said at least three oxide layers.

7. The magnetic recording medium according to claim 6, wherein each of said magnetic layer components having ferromagnetic grains and non-magneticmagnetic grain boundaries surrounding said ferromagnetic grains.

8. The magnetic recording medium according to claim 7, wherein said non-magneticmagnetic grain boundaries are composed of an oxide or nitride of at least one element selected from the group consisting of Cr, Co, Si, Al, Ti, Ta, Hf and Zr.

9. The magnetic recording medium according to claim 6, wherein said under-layer is composed of chromium or chromium alloy.

10. The magnetic recording medium according to claim 6, wherein said substrate is composed of one of a crystallized glass, a chemically strengthened glass and a plastic.

11. A method for manufacturing a magnetic recording medium comprising:

laminating a non-magneticmagnetic under-layer on a non-magneticmagnetic substrate;

laminating a magnetic layer on said under-layer by depositing a plurality of magnetic layer components, each of said magnetic layer components comprising ferromagnetic grains and grain boundaries surrounding said grains;

laminating a protective film on said magnetic layer; and

laminating a liquid lubricant layer on said protective film.

12. The method for manufacturing a magnetic recording medium according to claim 11, wherein said step for laminating said magnetic layer is a step of depositing a plurality of magnetic layer components, each component having different composition from one another.

13. The method for manufacturing a magnetic recording medium according to claim 11, wherein each step is performed without heating said substrate in advance.

15. The method for manufacturing a magnetic recording medium according to claim 14, wherein each step is performed without heating said substrate in advance.

14. A method for manufacturing a magnetic recording medium comprising:

laminating a non-magneticmagnetic under-layer on a non-magneticmagnetic substrate;

laminating a magnetic layer on said under-layer by

(i)exposing to an atmosphere of oxygen-containing gas and forming an oxide layer on a surface,

(ii) depositing a magnetic layer component comprising ferromagnetic grains and grain boundaries surrounding said grains,

(iii) repeating the procedures (i) and (ii) predetermined times, and

(iv) exposing to said atmosphere of oxygen-containing gas and forming an oxide layer on a surface;

laminating a protective film on said magnetic layer; and

laminating a liquid lubricant layer on said protective film.