Abstract: Polyoxymethylene articles having a surface printable with an ultraviolet-curing ink are obtained by molding a polyoxymethylene and treating the molded article by ultraviolet irradiation, corona discharge, or electron-beam radiation until the surface has an X-ray photoelectron spectrum in which the ratio of the ?C--O!.sub.n bond peak at 302 eV to the C--C bond peak at 305 eV, i.e., the ?C--O!.sub.n bond peak/C--C bond peak ratio, is at least 2.5.

Abstract: A magnetic recording medium whose magnetic layer formed on a base comprises a magnetic powder and a binder which contains a tertiary amine and uses 1,4-cyclohexanedimethanol as a chain extender. The magnetic powder is preferably of CrO.sub.2. The medium is made by mixing and dispersing the magnetic powder in a binder which consists of a reaction product of (A) a polyester which is a reaction product of a diol selected from among ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentadiol, and 1,6-hexanediol, and adipic acid, (B) a chain extender consisting of 1,4-cyclohexanedimethanol, (C) an aliphatic or aromatic diisocyanate in an amount substantially equal to the combined molar amount of the polyester and the chain extender, and (D) a tertiary amine, and applying the resulting magnetic coating material to a base.

Abstract: A magnetic recording medium comprising a plastic base and a magnetic layer formed thereon by applying a dispersion of a ferromagnetic powder in a resin binder, the magnetic layer containing the ferromagnetic powder which has a BET specific surface area of at least 35 m.sup.2 /g and .alpha.-Al2O3 particles having a particle size not exceeding one half the mean particle diameter of the ferromagnetic powder and less than 0.1 .mu.m in diameter, the .alpha.-Al2O3 particles being added in an amount greater than 5% but less than 15% by weight on the basis of the weight of the ferromagnetic powder. The magnetic powder is a metallic magnetic powder containing iron as the major constituent. The .alpha.-Al2O3 particles are cube-shaped.

Abstract: A magnetic recording medium, comprising a plastic base coated with a magnetic layer of a ferromagnetic powder dispersed in a resin binder, contains in the magnetic layer .alpha.-Al.sub.2 O.sub.3 particles with an average particle size of 0.1 to 0.3 .mu.m as determined by electron microscopy in an amount of more than 0.5% but less than 15% by weight on the basis of the ferromagnetic powder weight. The .alpha.-Al.sub.2 O.sub.3 particles have an .alpha.-transformation rate of at least 50%. The powder is produced by an organic alumina process.

Abstract: In a magnetic recording medium having a magnetic recording coat formed on one side of a base and a back coat on the other side, the back coat consists of a dispersion in a binder of an inorgainc pigment powder having an average particle diameter of 0.2 to 0.5 .mu.m and a Mohs hardness of not greater than 6. The binder consists of a specific copolymer, a rubber-like binder, and a polyisocyanate ingredient. The copolymer consists of vinyl chloride, a vinyl alkyl carboxylate, a monomer copolymerizable with vinyl chloride, and a saponified vinyl alkyl carboxylate and has an OH/CH absorption ratio as determined from its infrared absorption spectrum in the range of 0.2 to 0.7.

Abstract: A magnetic recording medium comprises a magnetic coating material, or a dispersion of magnetic particles in a resinous binder, and a base to which the coating material is solidly applied, the resinous binder comprising as its ingredients a copolymer composed of vinyl chloride, vinylidene chloride, a vinyl alkylcarboxylate, another monomer copolymerizable with vinyl chloride, and a saponified vinyl alkylcarboxylate and having an OH/CH absorption ratio according to the infrared absorption spectrum of at least 0.2, a polyurethane resin having in its molecule a --SO.sub.3 M group wherein M represents an alkali metal atom, and a polyisocyanate.

Abstract: A magnetic recording medium comprising a resinous component in which magnetic particles are dispersed and a base to which the dispersion is solidly applied, the resinous component consisting of a copolymer having an OH/CH absorption ratio according to the infrared absorption spectrum of 0.2 or more and made from (A) vinyl chloride, (B) vinylidene chloride, (C) a vinyl alkylcarboxylate, (D) an other monomer copolymerizable with vinyl chloride, and (E) a saponified vinyl alkylcarboxylate, and a rubbery binder. Alternatively, a polyisocyanate is added to the above copolymer.

Abstract: A magnetic recording medium which has dynamic range (I) of 70 dB or more and dynamic range (II) of 45 dB or more in control of a thickness of a magnetic layer and magnetic characteristics wherein said dynamic range (I) is given as a difference between an output at 3% input level of third harmonic wave output at a wavelength of 237.5 .mu.m in the optimum bias recording by a head having a recorded width of 1 to 1.1 mm based on an output of the original signal and a reproduced output calibrated by auditory sense calibration at non-signal recording in the bias and said dynamic range (II) is given as a difference between a saturated output at a wavelength of 4.75 .mu.m under the same condition and the reproduced output calibrated by the A-curve calibration at non-signal recording in the bias.

Abstract: A magnetic recording medium, comprising a magnetic layer and a non-magnetic substrate therefor, which magnetic layer is formed by dispersing magnetic powder in a vehicle formed of a copolymer containing vinyl chloride, another monomer copolymerizable with said vinyl chloride, a vinyl ester of an alkanoic acid and a saponification product thereof and having an OH/CH absorption ratio of 0.2 to 0.7 in the infrared absorption spectrum, and a rubbery binder.

Abstract: A magnetic recording medium having a magnetic layer comprising a magnetic powder and a resin binder, which is characterized by that the magnetic layer contains an ethylene trifluoride chloride polymer of a low degree of polymerization and a fatty acid ester.

Abstract: A magnetic recording medium having two coated magnetic layers of a first magnetic layer and a second magnetic layer on a non-magnetic substrate. The first magnetic layer has a coercive force of 400 to 590 Oe and a thickness of 2.1 to 2.8.mu. and said second magnetic layer has a coercive force of 590 to 800 Oe and a thickness of at least 2.1.mu..