Tdk Corporation

Other

Tsunehiko Ikarashi

Yasufumi Takasugi

Masahide Kohno

Takayoshi Kuwajima

Hiromichi Kanazawa

Yousuke Hitomi

Yuko Motegi

Takahiro Hayashi

Koji Kobayashi

Yuichi Kubota

Hideki Sasaki

Kunihiro Ueda

Tsutomu Aoyama

Osamu Inoue

Shinji Miyazaki

Akira Saitoh

Kazuhiro Kuroda

Katsuaki Yanagiuchi

Fuminori Tokuda

Yasushi Ishikawa

Takehiko Iritani

Lubricant composition and magnetic recording medium using the same

A magnetic recording medium includes a non-magnetic supporting substrate, and a magnetic layer on one surface thereof and a back coat layer on the other surface thereof, said back coat layer having a non-magnetic powder dispersed in a binder. The back coat layer contains carbon black and an inorganic powder as said non-magnetic powder. The carbon black contains a carbon black species having an average primary particle diameter of 40 to 70 nm, and the inorganic powder has an average primary particle diameter of 40 to 150 nm and a Mohs hardness of at least 3, with a weight ratio between said carbon black and said inorganic powder being 100:0.5 to 100:10. The binder comprises a phenoxy resin, a thermoplastic polyurethane resin having an amino group in a molecule thereof, and a polyisocyanate compound.

Magnetic recording medium

A magnetic recording (vapor deposition) film medium having improved friction characteristics, running durability, and still characteristics are provided. The magnetic recording thin film medium comprises a non-magnetic support having on at least one surface thereof a magnetic layer, a protective layer formed on the magnetic layer, and a lubricant layer formed on the protective layer, wherein the magnetic recording medium is obtained by that after forming the magnetic layer on the surface of the non-magnetic support conveyed along the surface of a cooling roll, a carbon-containing plasma polymerized film is formed on the magnetic layer as the protective layer, while conveying the non-magnetic support having the magnetic layer along the surface of a cooling roll, and after surface-treating the carbon-containing plasma polymerized film on the same cooling roll as the protective layer-forming roll or on a different cooling roll from the protective layer-forming roll without applying a bias voltage to the surface-treatment roll, whereby a double bond component of carbon and oxygen is incorporated in the surface of the carbon-containing plasma polymerized film at a ratio of from 1.4 to 7.5 atomic % to the whole carbon amount of the surface of the carbon-containing plasma polymerized film, and the lubricant layer made up of an ester of a fluorinated alcohol and a fatty acid is then formed on the carbon-containing plasma polymerized film.

A magnetic recording medium having an intermediate layer excellent in conductivity, surface properties and strength, and excellent in electromagnetic characteristics, physical properties, etc., which comprises a non-magnetic intermediate layer having a thickness of 0.5 .mu.m to 3.0 .mu.m formed on at least one surface of a non-magnetic support, and a magnetic layer formed on the intermediate layer, the magnetic layer being mainly composed of a ferromagnetic powder and a binder and having a thickness of 0.1 .mu.m to 0.5 .mu.m, in which said magnetic layer is formed on the intermediate layer at least in a dry state, and the intermediate layer comprises

Magnetic recording medium having a magnetic layer and an intermediate

A magnetic layer is provided on a nonmagnetic base with a non-ferromagnetic layer interposed between them. Non-ferromagnetic particulate iron oxide is incorporated in the non-ferromagnetic layer. In addition to, or in place of, this iron oxide, non-structural carbon having a mean particle diameter of 10 to 60 nm, a specific surface area of 150 m2/g as measured by the BET method and a DBP oil absorption of 100 ml/100 g or less may be used. This makes it possible to achieve a magnetic recording medium having excellent surface properties and good-enough electromagnetic transducing characteristics.

In a magnetic recording medium comprising on a non-magnetic substrate a magnetic layer obtained by dispersing ferromagnetic powder in an electron beam-curable resin followed by electron beam curing or a backcoat layer obtained by curing an electron beam-curable resin with electron beams, a combination of an electron beam-curable vinyl chloride resin having a sulfur-containing polar group and an electron beam-curable urethane resin having a phosphorus-containing polar group is used as the electron beam-curable resin. This results in improvements in dispersibility, surface smoothness, and electromagnetic characteristics, as well as a lowering of error rate in high density digital recording. Storage property is good.

In order to reduce the coefficient of friction of a coated type magnetic recording medium and improve the running stability and electromagnetic conversion characteristics thereof, a carbon black having a mean primary particle diameter of 25 to 65 m.mu.m with the standard deviation .sigma. of the particle size distribution lying at 12 to 24 m.mu.m is incorporated in the magnetic layer.

Magnetic recording medium having a magnetic layer comprising magnetic

In a magnetic recording medium comprising a substrate and a magnetic layer thereon, the magnetic layer is formed by coating a composition of a binder, preferably radiation-curable binder and a needle magnetic material, passing the coating through a magnetic field to forcedly re-orient the magnetic particles to form pores having an average pore area of 6.times.10.sup.-5 to 7.times.10.sup.-1 .mu.m.sup.2, and curing the coating, thereby minimizing output fluctuation and improving durability. Preferably lubricant is present in the pores.

Magnetic recording medium and preparation

Growing community of inventors

Nagano, Japan

Tsunehiko Ikarashi