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US 5,510,179 AGranted
Magnetic recording medium having at least two layers wherein the uppermost layer contains alumina particles which contain specified oxides
AssigneeTDK Corporation
InventorsKiyoto Fukushima, Sadafumi Iijima, Motoyuki Tsunoda
Life of this patent
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Abstract
A magnetic recording medium has at least two coating layers on a non-magnetic substrate. The uppermost layer of the coating layers is a magnetic layer having a thickness of 0.2-0.5 .mu.m thick and comprising a ferromagnetic powder, inorganic material-containing alumina particles having a mean particle size of 0.1-0.3 .mu.m, and a binder. The medium ensures effective head cleaning and has improved durability and still life.
Claims4
A magnetic recording medium comprising at least two coating layers on one surface of a non-magnetic substrate, wherein
- the uppermost layer of the coating layers is a magnetic layer having a thickness t of 0.2 to 0.5 .mu.m and containing 0.4-16% by weight of alumina particles containing an oxide of elements selected from the group consisting of Si, Fe, Ti, W, Mg, Mn and mixtures thereof and having a mean particle size d of 0.1 to 0.3 .mu.m, wherein the ratio t/d is a number in the range of from 1:1 to 4:1, wherein the oxide contained in the alumina particles is present in a total amount of 0.05 to 5.0% by weight of the alumina particles when calculated as SiO.sub.2, Fe.sub.2 O.sub.3, TiO.sub.2, WO.sub.3, MgO and MnO.
Dependencies are inferred from the claim text.