Abstract: A cleaning jacket for a magnetic head used for flexible discs comprising a cleaning sheet and a sheet retaining jacket, the cleaning sheet comprising a flexible and non-magnetizable support, at least on one surface of which is provided an antistatic layer and on the other surface of which is provided a cleaning layer of a fibrous material, the retaining jacket having the shape of a flat casing and defining a space in which the cleaning sheet can be kept in such a manner that it can rotate freely therein, and, further, having a lubricating layer provided on the inner wall thereof facing the antistatic layer of the cleaning sheet.

Abstract: A soft, coarse, porous cleaning sheet 32 is adhered to the upper surface of a flat horizontal base plate 2, and has approximately the same configuration as the base plate. A floppy record disc 9 having a magnetic layer 10 is secured to the spindle 6 of a motor 5, and when the disc is rotated at a "below levitation" speed the layer 10 slidingly engages the cleaning sheet 32 and is scrape dusted clean thereby.

Abstract: This invention relates to a magnetic recording medium comprising a ferromagnetic metal thin film as a magnetic recording layer on a non-magnetic flexible support, in which the surface roughness of the support is 0.10 .mu.m or less and the period of the surface roughness is v/10.sup.6 .mu.m or less where v represents a relative speed between a magnetic head and magnetic recording medium by .mu.m/sec. In the case of providing an undercoated layer between the magnetic recording layer and non-magnetic flexible support, the surface roughness of the undercoated layer is adjusted to 0.10 .mu.m or less and the period of the surface roughness is adjusted to v/10.sup.6 .mu.m or less.

Abstract: This invention relates to a method of forming a metallic thin film on a plastic substrate by electroless plating, which comprises providing an undercoated layer consisting essentially of polyvinylidene chloride or vinylidene chloride copolymer on the surface of the plastic substrate and then subjecting to a surface activating treatment and electroless plating.

Abstract: A magnetic recording medium comprising a support, a magnetic recording layer comprising a thin film of a ferromagnetic metal on the support, and at least one monomolecular layer comprising a saturated fatty acid or a metal salt thereof on the surface of the magnetic recording layer.

Abstract: An improved method of making a magnetic recording material comprises providing a ferromagnetic metal thin layer which has uniaxial anisotropy in any direction on a web by means of plating.A plating solution is jetted onto the web through holes in a conveying pipe set in a plating bath. The web is then moved from the vicinity of the conveying pipe by the spouting force of the plating solution, and then conveyed along a helical path about the conveying pipe without contacting the surface of conveying pipe. Plating occurs while applying a magnetic field to the web.

Abstract: The magnetic recording medium comprising a nonmagnetizable base having provided thereon a magnetizable layer by electroless plating, said magnetizable layer containing at least one ferromagnetic metal, phosphorus and at least one of copper, lead and silicon.

Abstract: In a process for producing ferromagnetic powder which comprises adding an aqueous solution containing Co.sup.+2 ions, with or without another cation or cations, and an alkali solution to a suspension of ferromagnetic iron oxide, and heating the mixture to produce ferromagnetic iron oxide containing the metal provided by such an ion (s), the improvement wherein the heating is carried out in the presence of an oxidizing agent.

Abstract: Co- and Fe-containing ferromagnetic iron oxide powder having a high coercive force and improved stability to heat and pressure is produced by adding an aqueous alkali solution, an aqueous solution containing Co.sup.+2 ions, and an aqueous solution containing not more than 1 equivalent, based on the Co.sup.+2 ions, of Fe.sup.+3 ions to a suspension of a ferromagnetic iron oxide, and heating the mixture at a temperature of at least about 80.degree. C, preferably 90.degree. to 105.degree. C. The ferromagnetic iron oxide powder is especially suitable for producing magnetic recording media.

Abstract: A Co- and Fe-containing ferromagnetic iron oxide powder having a high coercive force and improved stability to heat and pressure is produced by adding an aqueous alkali solution, an aqueous solution containing Co.sup.+2 ions, and an aqueous solution containing not more than 1 equivalent, based on the Co.sup.+2 ions, of Fe ions to a suspension of ferromagnetic iron oxide, and heating the mixture at a temperature of at least 80.degree. C in the presence of an oxidizing agent. The ferromagnetic iron oxide powder is especially suitable for producing magnetic recording media.

Abstract: Ferromagnetic powders comprising cobalt and/or nickel are produced by reducing cobalt and/or nickel salts in an aqueous solution containing hypophosphite ions while applying a magnetic field.

Abstract: A process for stabilizing a ferromagnetic material comprising heat-treating a needle-like ferromagnetic material represented by the formula MO.sub.x wherein M is a ferromagnetic metal ion or a ferromagnetic non-metal ion and another metal ion, and x is the degree of oxidation which ranges from 1.36 to 1.47, and containing at least 0.5 atom % Co, at a temperature of at least about 40.degree. C, and a process for stabilizing a magnetic recording member comprising heat-treating a magnetic recording member produced by providing a ferromagnetic recording layer comprising (a) a ferromagnetic material represented by the formula MO.sub.x wherein M and x are the same as defined above, and containing at least 0.5 atom % Co, and (b) a binder, on a support, at a temperature of at least about 40.degree. C.

Abstract: An improved method of making a magnetic recording medium with excellent coercive force and rectangular ratio is provided by means of an ion plating technique. A support and an evaporation source of a magnetic Co-Si alloy are placed in an ion plating apparatus which is filled with an inert gas and kept at low vacuum. High voltage is then applied between the support and the evaporation source such that the former has a negative polarity and the latter a positive polarity, thereby causing a glow discharge zone in the apparatus. The magnetic alloy is evaporated into the glow discharge zone from the source to form a magnetic thin film on the support. Such a magnetic thin film can have a coercive force of 750 Oe or more and a rectangular ratio of 0.80 or more and can be used as a magnetic recording medium.

Abstract: A magnetic recording member comprising a non-magnetic support having a magnetic recording layer on one side of the non-magnetic support and a lubricating layer on the other side of the non-magnetic support in which the lubricating layer comprises a liquid or semi-solid lubricant or a liquid or semi-solid lubricant, and an organic binder.

Abstract: A foldable jacket made of a sheet material of rectangular shape and folded at the central portion thereof to form a square base sheet and a square cover sheet. The cover sheet is provided with a cut-away portion extending from an edge opposite to the folded edge to the central part thereof. The base sheet is provided with a disc holding portion at the central part thereof to be engaged with a central hole of the disc. The disc holding portion is composed of a stem portion and engaging portions. The engaging portions are made flexible and releasably engaged with the hole of the disc.

Abstract: This invention relates to a magnetic recording medium, which comprises a first protective plating layer consisting of at least one selected from the group consisting of rhenium, osmium, ruthenium, chromium, rhodium and mixtures thereof, provided on a ferromagnetic thin layer plated on a non-magnetic base material by a plating method, and a second protective plating layer consisting of at least one selected from the group consisting of silver, gold, copper, platinum, palladium, nickel-phosphorus alloys and mixtures thereof, further provided on the first protective plating layer.