Magnetic recording medium

• US 4,689,265 A
• Filed: 10/30/1985
• Issued: 08/25/1987
• Est. Priority Date: 10/31/1984
• Status: Expired due to Term

• Current Assignee: Fuji Photo Film Company
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Miyoshi, Takahito, Fujiyama, Masaaki
• Primary Examiner(s): Robinson, Ellis P.
• Application Number:
  US06/792,896
• Time in Patent Office: 664 Days
• Field of Search: 252/62.54, 252/62.55, 428/694, 428/900, 428/328, 428/329, 428/323, 360/134-136, 427/128, 427/645
• US Class Current: 428/323
• CPC Class Codes: G11B 5/708 characterised by addition of non-magnetic particles to the layer
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles
• CPC Class Codes: Y10S 428/90 Magnetic feature
• 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 428/256 Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/257 Iron oxide or aluminum oxide

Abstract

A magnetic recording medium comprising a nonmagnetic support and a magnetic recording layer provided on said support, said magnetic recording layer comprising a ferromagnetic powder dispersed in a binder, characterized in that said magnetic recording layer contains an inorganic plate powder having the maximum diameter of not larger than 1.0 μm and a thickness of not larger than 0.1 μm.

Claims

1. In a magnetic recording medium comprising a non-magnetic support and a magnetic recording layer provided on said support, said magnetic recording layer comprising a ferromagnetic powder dispersed in a binder, the improvement which comprises said magnetic recording layer contains an Al ₂ O₃ plate powder having a diameter in the range of 0.05 to 1.0 μ

m and a thickness in the range of 0.001 to 0.1 μ

m, said Al₂ O₃ plate powder being contained in the recording layer in an amount of not more than 10% by weight of the ferromagnetic metal powder and said ferromagnetic powder being a ferromagnetic metal powder having a specific surface area of not less than 40 m² /g.

2. The magnetic recording medium as claimed in claim 1, wherein the maximum diameter of said Al₂ O₃ plate powder is in the range of 0.05 to 0.8 μ

m.

3. The magnetic recording medium as claimed in claim 1, wherein the maximum diameter of said Al₂ O₃ plate powder is 3 to 200 times larger than the thickness thereof.

4. The magnetic recording medium as claimed in claim 2, wherein said Al.sub. 2O.sub. 3 plate powder is contained in the recording layer in an amount of 0.1 to 8 % by weight of the ferromagnetic powder.

5. The magnetic recording medium as claimed in claim 1, wherein said magnetic recording layer further contains a granular filler.

6. The magnetic recording medium as claimed in claim 1, wherein said ferromagnetic powder is a ferromagnetic metal powder having a specific surface area of not less than 45 m.sup. 2/g.

7. The magnetic recording medium as claimed in claim 6, wherein said Al₂ O₃ plate powder has a maximum diameter in the range of 0.05 to 0.8 μ

m which is 3 to 200 times larger than the thickness thereof, and wherein said powder is contained in the recording layer in an amount of 0.1 to 8% by weight of the ferromagnetic powder.

8. The magnetic recording medium as claimed in claim 7, wherein the maximum diameter of said Al₂ O₃ plate powder is 7 to 100 times larger than the thickness thereof and said Al₂ O₃ plate powder is contained in the recording medium in an amount of 0.2 to 7% by weight of the ferromagnetic powder.

9. The magnetic recording medium as claimed in claim 3, wherein the maximum diameter of said Al₂ O₃ plate powder is 7 to 100 times larger than the thickness thereof.

10. The magnetic recording medium as claimed in claim 4, wherein said Al₂ O₃ plate powder is contained in the recording layer in an amount of 0.2 to 7 weight % by weight of the ferromagnetic powder.