Abstract: To enable high density mass storage recording, for an upper magnetic layer, the length of a major axis of metallic magnetic powder, the type of binder, the hardness and particle size of abrasive powder, the condition of kneading, surface roughness and thickness are regulated, for a lower nonmagnetic layer, the length of a major axis of nonmagnetic powder, the ratio of the length of a major axis to that of a minor axis and the type of binder are regulated and further, a method of forming the upper magnetic layer and the lower nonmagnetic layer, the thickness of a nonmagnetic base material and Young's modulus are regulated.

Abstract: A method of manufacturing a magnetic recording medium having excellent magnetostatic and electromagnetic conversion properties for high density recording is provided, wherein magnetic powder (P) is kneaded with a binding agent (B) mainly comprising low molecular weight vinyl chloride resin whose number-average molecular weight is 8000 to 20000 with a P/B ratio of 7 or more before preparing the magnetic coating material so as to be coated on a non-magnetic base material.

Abstract: A magnetic recording medium wherein a magnetic metal film has been formed on one surface of a non-magnetic substrate, and a back coat resulting from a non-magnetic pigment dispersed among a binder has been formed on the other, or reverse to the side upon which the magnetic film has been formed, characterized by that each of the chloride and sulfate ion contents of the back coat, according to the analysis by ion chromatography of its pure water extract, is not more than 5 ppm, and that the binder acting as a constituent of the back coat contains at least polycarbonate urethane.

Abstract: A process for preparing a magnetic recording medium capable of exhibiting excellent magnetostatic properties, electromagnetic conversion properties and travel durability in a high density recording region, is disclosed, which process includes the steps of mixing a magnetic powder having a major axis length of 0.1 .mu.m or less, a first binder composed primarily of a vinyl chloride-based copolymer composed of a sulfonate group and/or a group derived from quaternary ammonium salt, a hydroxyl group and an epoxy group and having an average degree of polymerization of 100 to 200, and a first solvent with each other to form a mixture, and dispersing and diluting the mixture by adding a non-magnetic hard inorganic powder, a second binder and a second solvent to the mixture to prepare a magnetic coating material.