Tdk Corporation

Sadafumi Iijima

Takayoshi Kuwajima

Kenichi Kitamura

Kiyoto Fukushima

Motoyuki Tsunoda

A high recording density magnetic recording medium and a manufacturing method therefor are provided. The dilution stability during preparation of magnetic paint is improved and, thereby, even when the magnetic paint concentration is lowered, no problem occurs with the surface roughness and the output of the thin magnetic layer. The magnetic recording medium includes at least a magnetic layer on one surface of a non-magnetic support, wherein the magnetic layer contains a magnetic powder, a vinyl chloride resin having a degree of polymerization of at least 270 and an aliphatic polyester polyurethane resin to serve as binder resins, an aromatic compound having a substituent R (where R is &#x2014;COOH, &#x2014;(COOH), &#x2014;OPO(OH), &#x2014;PO(OH), or &#x2014;SOH), and a phosphoric acid ester. The ratio of binder resins in the magnetic paint is set at 2.0 percent by weight or less relative to a total sum of the binder resins and a solvent.

Magnetic recording medium and method for manufacturing the same

The present invention provides a high recording density magnetic recording medium with excellent surface smoothness, as well as excellent electromagnetic conversion characteristics and durability. A magnetic recording medium comprising a lower non-magnetic layer containing at least a non-magnetic powder and a binder resin on a non-magnetic support, and an upper magnetic layer with a thickness of 0.2 &#x3bc;m or less on said lower non-magnetic layer, wherein said lower non-magnetic layer contains an acicular powder of hydrated iron oxide as the non-magnetic powder, and said lower non-magnetic layer contains a fatty acid and a fatty acid amide. Preferably the acicular powder of hydrated iron oxide is goethite with an average long axial length of 0.15 &#x3bc;m or less.

Magnetic recording medium

The present invention provides a high recording density magnetic recording medium with improved dropout and excellent surface smoothness and electromagnetic conversion characteristics, as well as a process for producing such a medium. A magnetic recording medium comprising a lower non-magnetic layer containing at least a non-magnetic powder and a binder resin on one surface of a non-magnetic support, an upper magnetic layer containing at least a ferromagnetic powder and a binder resin on said lower non-magnetic layer, and a back coat layer on an opposite surface of said non-magnetic support, wherein said lower non-magnetic layer contains an acicular powder of hydrated iron oxide as the non-magnetic powder, said ferromagnetic powder has an average long axial length of 0.1 &mgr;m or less, and said upper magnetic layer has a surface roughness (center line average roughness: Ra) of 2.4 nm or less. After curing the lower non-magnetic layer, the magnetic layer is applied and formed.

Magnetic recording medium and process for producing the same

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.

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Yamanashi, Japan

Sadafumi Iijima