Magnetic recording medium having a magnetic layer and a coating thereunder
AssigneeImation Corp.
InventorsShigeto Oiri, Yoji Tsukamoto, Hideaki Yasui
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Abstract
A magnetic recording medium comprising a nonmagnetic substrate, a liquid lubricant-containing coating layer having a porosity (U) formed on the substrate, and a magnetic layer having a porosity (M) formed directly on the coating layer. The ratio of porosity (U/M) between the coating and magnetic layers is between 0.75 and 1.25. The volume percentage of the lubricant contained in the pores of the coating layer based on the whole pore volume in the coating layer is from 35 to 85%. This improves the durability of the magnetic layer.
Claims14
A magnetic recording medium comprising a nonmagnetic substrate, a porous, liquid subricant-containing coating layer formed on the substrate, and a magnetic layer formed directly on the coating layer, wherein the coating layer comprises a liquid lubricant, a binder, and a nonmagnetic powder, the maximum amount of liquid lubircant that can be absorbed by a layer per unit volume of the layer is defined by U for the coating layer and M for the magnetic layer, wherein 0.75≦M/U≦1.25, and the lubricant is present in an amount of from 5 to 11 parts by weight per 100 parts by weight of the nonmagnetic powder, and wherein the magnetic recording medium is a disk shape having a diameter of about 89 mm.
Dependencies are inferred from the claim text.