Longitudinal magnetic coated recording medium

• US 4,746,569 A
• Filed: 05/14/1986
• Issued: 05/24/1988
• Est. Priority Date: 05/20/1985
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Takahashi, Jun, Fukushima, Shigeru, Itoh, Ken-ichi, Ogawa, Seiya, Narumi, Toshikatu
• Primary Examiner(s): Thibodeau, Paul J.
• Application Number:
  US06/863,039
• Time in Patent Office: 741 Days
• Field of Search: 428/323, 428/694, 428/900, 427/122
• US Class Current: 428/323
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/70652 gamma - Fe2 O3
• CPC Class Codes: G11B 5/70678 Ferrites
• 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: G11B 5/845 in a magnetic field
• 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

Abstract

A longitudinal magnetic coated recording medium comprises at least plane magnetic particles each having an easy magnetization axis perpendicular to the major surface thereof, preferably mixed with other particles, and dispersed in a magnetic film formed on a nonmagnetic substrate, having a orientation angle of -30° to +30°. A process for producing such a recording medium comprises the step of orienting the plane magnetic particles by applying at least a magnetic field approximately in parallel to the surface of the magnetic film.

Claims

1. A longitudinal magnetic coated recording medium, comprising:

a nonmagnetic substrate having a magnetic film formed thereon including a magnetic film plane; and

plane magnetic particles, each having an easy magnetization axis perpendicular to a major surface thereof and dispersed in said magnetic film, the orientation angle of said particles being in the range of from-30°

to +30°

, said orientation angle being determined by an angle where the ratio of residual magnetization to saturation magnetization Mr/Ms, is largest, and said orientation angle being defined as the angle between the magnetic film plane and said easy axis of magnetization.

2. A recording medium according to claim 1, wherein the ratio of residual magnetization to saturation magnetization Mr/Ms in a direction parallel to the surface of said magnetic film is at least 0.65.

3. A recording medium according to claim 1, characterized in that said magnetic film contains other particles mixed with said plane magnetic particles in an amount of 10 to 30% based on the total weight of said plane magnetic particles and said other particles.

4. A recording medium according to claim 1, characterized in that said plane magnetic particles are hexagonal crystals selected from the group consisting of barium ferrite and strontium ferrite.

5. A recording medium according to claim 3, characterized in that said other particles are magnetic particles different from said plane magnetic particles.

6. A recording medium according to claim 5, characterized in that said other magnetic particles are acicular γ

-Fe₂ O₃ or cobalt adsorbed γ

-Fe₂ O₃.

7. A recording medium according to claim 3, characterized in that said magnetic film contains nonmagnetic particles.

8. A recording medium according to claim 7, characterized in that said nonmagnetic particles are selected from the group of α

-Fe₂ O₃, α

-Al₂ O₃ and SiO₂.

9. A recording medium according to claim 1, characterized in that a particle diameter of said plane magnetic particles is in the range of 0.1 to 0.3 μ

m.

10. A recording medium according to claim 3, characterized in that the size of said other particles is in the range of 0.05 to 0.4 μ

m.