Magnetic recording medium
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsTakashi Suzuki, Kunio Hibino, Mikio Murai, Shigeki Kawase, Koichi Shinohara
Life of this patent
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Abstract
A magnetic recording media, e.g. VTR tape is improved by providing an undercoating layer on a polyester film substrate, the undercoating layer being formed under a ferromagnetic thin film and being an even-scattering of a large number of inorganic or organic granules distributed at a rate of 1000/mm.sup.2 or more.
Claims15
A magnetic recording medium comprising:
- a substrate of plastic film,
- an undercoating layer having 1000/mm.sup.2 or more minute granular protrusions of 30 to 500 .ANG. in height provided that the lateral spread is in the range of 1:1 to 20:1, said undercoating layer being formed as a coating on the face of said substrate,
- a ferromagnetic thin film formed on said undercoating layer, and
- a lubrication layer formed on said ferromagnetic thin film wherein said granular protrusions comprise nuclei of at least one substance selected from the group consisting of a thermoplastic resin, a crosslinked resin, carbon, an oxide of a metal and the hydrolysis product of a metal alkoxide.
A magnetic recording medium exhibiting an improved still life while avoiding tape squeal under high temperature and high humidity conditions, said medium comprising
- a plastic film substrate;
- an undercoating layer having at least 1,000 minute granular protrusions substantially uniformly distributed per square millimeter, the granular protrusions ranging from 30 to 500 .ANG. in height provided that the lateral spread is from 1:1 to 20:1, formed on the substrate;
- a ferromagnetic thin film formed on the undercoating layer;
- and
- a lubrication layer formed on at least those portions of the ferromagnetic film overlying the protrusions wherein said granular protrusions comprise nuclei of at least one substance selected from the group consisting of a thermoplastic resin, a crosslinked resin, carbon, an oxide of a metal and the hydrolysis product of a metal alkoxide.
A magnetic recording medium exhibiting an improved still life while avoiding tape squeal under high temperature and high humidity conditions, said medium comprising
- a plastic film substrate;
- an undercoating layer having at least 1,000 minute granular protrusions substantially uniformly distributed per square millimeter, the granular protrusions ranging from 30 to 500 .ANG. in height provided that the lateral spread is from 1:1 to 20:1, formed on the substrate, the granular protrusions formed by nuclei retained on the substrate by a resin binder;
- a ferromagnetic thin film formed on the undercoating layer;
- and
- a lubrication layer formed on at least those portions of the ferromagnetic film overlying the protrusions wherein said granular protrusions comprise nuclei of at least one substance selected from the group consisting of a thermoplastic resin, a crosslinked resin, carbon, an oxide of a metal and the hydrolysis product of a metal alkoxide.
Dependencies are inferred from the claim text.