Abstract: A lubricant compound which comprises carbon, hydrogen, fluorine and etheric oxygen atoms and which contains perfluoropolyether chain of the formula (A), a perfluoroalkyl chain of the formula (B) and a polyether chain of the formula (C) in combinations of (A) and (C), (B) and (C), or (A) and (C) and of (B) and (C), in a molecule wherein:A is --(C.sub.n F.sub.2n O).sub.m --,wherein n is an integer of 1 to 10 and m is an integer of at least 1;B is --C.sub.n F.sub.2n --,wherein n is an integer of 1 to 15, andC is --(C.sub.n H.sub.2n O).sub.m --,wherein n is an integer of 1 to 6 and m is an integer of at least 1.

Abstract: A magnetic recording medium comprising a substrate and a ferromagnetic metal layer, wherein the ferromagnetic metal layer includes hydrated amorphous cobalt oxide, a X-ray photoelectron spectra which is characterized in that, in the Co.sub.2p spectrum, a ratio of a peak height at 785.9.+-.0.3 eV to that at 780.0.+-.0.3 eV is 40/100 or less when a background (BG) line is drawn between lower energy side leading edge points of peaks at 780.0.+-.0.3 eV (2p.sub.3/2) and 795.6.+-.0.3 eV (2p.sub.1/2) and, in the O.sub.1s spectrum, a ratio of a peak height at 529.3.+-.0.4 eV to that at 530.8.+-.0.4 eV is from 100:110 to 100:50 when a background line is drawn between the lower energy side leading edge point and the higher energy side leading edge point of a complex peak at 530.5.+-.2.5 eV from which the peaks at 529.3.+-.0.4 eV and 530.8.+-.0.4 are derived by peak synthesis, which has good corrosion and wear resistance.

Abstract: A magnetic recording medium comprising a substrate and, as a recording layer, a ferromagnetic metal thin layer formed on the substrate by deposition, in which the ferromagnetic metal thin layer contains oxygen atom in such a manner that concentrations of oxygen atom in a surface layer and an interfacial layer adjacent to the substrate are higher than that in an intermediate layer between the surface and interfacial layers, which has an improved coercive force and smaller magnetic domain.

Abstract: In a recording tape cartridge having a cartridge case, magnetic recording tape and a front lid and a rear lid for protecting the magnetic tape, there are provided entrance preventing members at a bottom the cartridge case facing to clearances between side edges of the front lid and case body for preventing entrance of harmful floating particles into the area near the recording tape so as to prevent corrosion of the recording tape.

Abstract: A magnetic recording medium comprising a substrate and, as a recording layer, a ferromagnetic metal thin layer formed on the substrate by deposition, in which the ferromagnetic metal thin layer contains oxygen atom in such a manner that concentrations of oxygen atom in a surface layer and an interfacial layer adjacent to the substrate are higher than that in an intermediate layer between the surface and interfacial layers, which has improved coercive force and smaller magnetic domain.

Abstract: A magnetic recording medium comprising a substrate, a magnetic layer provided thereon, a passivated film formed on the surface of said magnetic layer, and a lubricant-containing back-coat layer whose pH is adjusted to 6.3 or more on the back of said substrate.