Magnetic recording medium having an upper magnetic layer and a lower magnetic layer comprising ferromagnetic powder, carbon black and a specified polyurethane binder

摘要

Disclosed is a magnetic recording medium having a first magnetic layer 2 and a second magnetic layer 4 laminated on a non-magnetic support in this order, wherein the binder in the lower first magnetic layer 2 comprises only polyurethane resin(s) having tertiary amines as polar groups or only said polyurethane resin(s) and a curing agent or comprises a mixed system composed of polyurethane resin(s) having tertiary amines as polar groups and amine-modified vinyl chloride-based resin(s) or of these resins and a curing agent. The first magnetic layer 2 may contain carbon black having a specifically-defined mean particle size. The coatability of the magnetic coating compositions is improved. The electromagnetic conversion characteristics (especially, video S/N, chroma output power, chroma S/N) of the medium are improved. Since the crosslinking of the components constituting the lower magnetic layer is improved, the dropout of the medium is not increased even after stored. This invention provides a magnetic recording medium capable of being subjected to long-sustained, high-quality recording and reproduction in severe conditions. The medium has high electric resistance, high light transmittance and good running durability, even though not having a back coat layer.