Abstract: A nonaqueous secondary battery comprising a positive electrode and a negative electrode both containing a material capable of reversibly intercalating and deintercalating lithium, a nonaqueous electrolyte containing a lithium salt, and a separator, which has a least one protective layer on the negative electrode and/or the positive electrode. The battery has a high discharge potential, satisfactory charge and discharge cycle characteristics, and high safety.

Abstract: A nonaqueous secondary battery comprising a positive electrode and a negative electrode both containing a material capable of reversibly intercalating and deintercalating lithium, a nonaqueous electrolyte containing a lithium salt, and a separator, which has at least one protective layer on the negative electrode and/or the positive electrode. The battery has a high discharge potential, satisfactory charge and discharge cycle characteristics, and high safety.

Abstract: A magnetic recording medium is disclosed, comprising a nonmagnetic support having thereon a magnetic layer, said magnetic layer comprising ferromagnetic particles and a binder, wherein nonmagnetic support has a transverse-direction Young's modulus of at least 1,000 Kg/mm.sup.2, said magnetic layer has a glass transition temperature of 80.degree. to 100.degree. C., and said magnetic recording medium has a total thickness of less than 12 .mu.m, and further a magnetic recording medium is disclosed, comprising a nonmagnetic support having thereon a magnetic layer, said magnetic layer comprising ferromagnetic particles and a binder, wherein said magnetic recording medium is adapted for use with a magnetic head having a core width of at least 100 .mu.m at a speed of at least 20 m/sec based upon relative speed of said recording medium and said head, said nonmagnetic support has a transverse-direction Young's modulus of at least 1,000 Kg/mm.sup.2, said magnetic layer has a glass transition temperature of from 80.

Abstract: A magnetic recording medium comprising a non magnetic support having thereon a magnetic layer comprising binder resins, ferromagnetic particles and an organic phosporus compound.

Abstract: A novel magnetic disc and process for the preparation thereof is disclosed, comprising a nonmagnetic support having thereon a magnetic layer comprising ferromagnetic metal particles and a binder resin containing at least a vinyl chloride copolymer, wherein the crystallite size of the ferromagnetic metal particles as determined by X-ray diffraction method is 300 .ANG. or less, and the ratio .alpha. at the surface of the magnetic layer of the integrated intensity of the Cl-2P spectrum as determined by X-ray photoelectron spectroscopy to that of the Fe-2P(3/2) spectrum is in the range of from 0.50 to 0.90. In a preferred embodiment, the vinyl chloride copolymer contains at least one polar group selected from the group consisting of --SO.sub.3 M, --OSO.sub.3 M, --PO.sub.3 M.sub.2, and --CO.sub.2 M wherein M represents hydrogen, an alkali metal or ammonium and at least one epoxy ring in the copolymer molecule.

Abstract: A magnetic disc having excellent running durability is disclosed, which comprises a non-magnetic support and a magnetic layer on the non-magnetic support, the layer being composed mainly of a ferromagnetic metal powder and a binder resin, wherein the ferromagnetic metal powder has a pH value of less than 7.0 and a specific surface area as determined by the BET method of at least 40 m.sup.2 /g, and the glass transition temperature of the magnetic layer is at least 75.degree. C.

Abstract: A magnetic recording medium comprising a non-magnetic support having thereon a magnetic layer comprising ferromagnetic metal powder and a binder, the magnetic layer further comprising carbon black having an average particle diameter of 250 m.mu. or more in an amount of from 1 to 10 parts by weight per 100 parts by weight of the ferromagnetic metal powder, and an ester of tridecyl alcohol with stearic acid and/or an ester of tridecyl alcohol with palmitic acid in an amount of from 5 to 20 parts by weight per 100 parts by weight of the ferromagnetic metal powder.

Abstract: A magnetic recording medium is disclosed, comprising a nonmagnetic support having thereon a magnetic layer comprising ferromagnetic metal particles and binder resins, in which 35 to 55% by weight of said binder resins are a polar group-containing vinyl chloride copolymer and 10 to 25% by weight of said binder resins are a polyurethane resin obtained by the reaction of a polyisocyanate with a polyester polyol that is a product of the reaction of at least one of an alicyclic dihydric alcohol and an aromatic dihydric alcohol with at least one of an alicyclic dicarboxylic acid and an aromatic dicarboxylic acid, said polyurethane resin containing a polar group selected from the group consisting of --SO.sub.3 M, --COOM, --PO.sub.3 M wherein M is an H, Na, or K atom, and --NH.sub.2 in an amount of from 0.03 to 2% by weight, the amount of said binder resin in the magnetic layer being from 15 to 30 parts by weight per 100 parts by weight of said ferromagnetic metal particles.

Abstract: A magnetic recording medium is disclosed, comprising a nonmagnetic support having thereon a magnetic layer comprising mainly ferromagnetic metal particles of a specific surface area and binder resins, wherein at least part of said binder resins is a cellulosic resin having in side chains of the molecules thereof a polar group which is a sulfonic acid group, a metal sulfonate group, a phosphoric acid group, or a metal phosphate group.

Abstract: A novel flexible magnetic disc is provided comprising a protective layer on the periphery of a central hole, wherein the protective layer comprises of two layers, the lower one of the two layers being a composition mainly composed of a printing ink and the upper one being a composition mainly composed of a resin obtained by irradiating a radiation-polymerizable compound with radiation so that it cures.

Abstract: A magnetic disk comprising a nonmagnetic support having provided thereon a magnetic layer comprising a ferromagnetic metal powder and a binder resin, wherein the magnetic layer has a mechanical loss tangent, tan .delta., of from 8.times.10.sup.-3 to 6.times.10.sup.-2, measured at a frequency of 110 Hz and in a temperature range of from 20.degree. to 50.degree. C. with a temperature increase rate of 2 deg/min.

Abstract: A magnetic recording medium is disclosed, comprising a nonmagnetic support having thereon a magnetic layer, wherein at least one of ester compounds represented by formula (I) is present in or on the magnetic layer, ##STR1## wherein R.sub.1 represents a straight chain, saturated alkyl group having 6 to 12 carbon atoms, R.sub.2 represents a straight chain, saturated alkyl group having 4 to 10 carbon atoms, and R represents a branched or straight chain alkyl group having 4 to 22 carbon atoms.

Abstract: A magnetic recording medium having on a non-magnetic support a magnetic layer mainly composed of a ferromagnetic metal powder and a binder resin is disclosed, wherein the specific surface area S (m.sup.2 /g) of the ferromagnetic metal powder is from 30 to 65 and the magnetic layer further contains a fatty acid ester in a content Y (% by weight) to the ferromagnetic metal powder of the range of 0.05S+5.5.ltoreq.Y.ltoreq.-0.2S+24 when the specific surface area S is from 30 to less than 50 and the range of 0.06S+4.7.ltoreq.Y.ltoreq.-0.13S+21 when the specific surface area S is from 50 to 65. The magnetic recording medium is suitable for high density recording and exhibits excellent running durability.

Abstract: A magnetic recording medium is described, comprising a nonmagnetic support having thereon a magnetic layer containing ferromagnetic particles which are a hexagonal system tabular particle, and which have an axis of easy magnetization in a direction of perpendicular to the major axis of the plate and are dispersed in a binder, wherein said ferromagnetic particles have a saturation magnetization of 60 emu/g or higher, a specific surface area (BET method) of from 25 to 70 m.sup.2 /g, an average particle diameter of from 0.01 to 0.2 .mu.m, and a coercive force of from 400 to 2000 oersteds, and said biner contains a resin having at least one kind of polar group in an amount of 1.times.10.sup.-5 eq/g or more of the polar group.

Abstract: A magnetic recording medium is disclosed, comprising a nonmagnetic support having thereon a magnetic layer containing ferromagnetic particles which are dispersed in a binder and have a tabular hexagonal crystal shape with an axis of easy magnetization perpendicular to the plate, wherein said ferromagnetic particles have a specific surface area of from 50 to less than 70 m.sup.2 /g, and further said magnetic layer contains abrasive agents having a Mohs' hardness of 6 or more and having an average particle diameter of from 0.3 to 1.0 .mu.m in an amount of from 7 to 15 parts by weight per 100 parts by weight of the ferromagnetic particles.

Abstract: A flexible magnetic disk sheet including a central circular hole is described, having a protective layer on a surface portion surrounding the edge of the central circular hole, comprising the protective layer prepared by coating (a) a compound having an acrylate bond or a methacrylate bond at the end of at least one of a main chain and a side chain of molecules thereof, and (b) a solid lubricating agent, and exposing to radiation thereon for polymerizing and hardening it.

Abstract: A flexible magnetic disk in which the friction between the magnetic sheet of the disk and a positioning member is reduced, the magnetic sheet is positioned properly and without offset each time it is loaded in a reading/reproducing device, and the tracking accuracy and dimensional accuracy are satisfactory. A protective layer is provided around the periphery of a central hole in the magnetic sheet. The protective layer is made of a composition containing a compound which has an acrylic or methacrylic acid ester bond at one or both of a main chain terminal and a side chain thereof. The compound is one which is cured by radiation. The thickness of the protective layer should be 30 microns or less, and the surface irregularity of the protective layer should be 0.03 microns or more represented in terms of a central line average roughness at a cutoff of 2.5 mm.

Abstract: A method for forming protective layer on a surface portion surrounding the edge of a central aperture of a flexible magnetic disc sheet is described, comprising providing a radiation polymerizable composition on a surface portion surrounding the edge of the central aperture of the flexible magnetic disc sheet by screen printing, and hardening the composition by exposure to radiation; a flexible magnetic disc is also described, wherein a protective layer by the foregoing method is provided, with said protective layer having an inner diameter larger than the diameter of the aperture of the disc sheet and an outer diameter smaller than the diameter of the aperture of a jacket enclosing the disc sheet.

Abstract: In a method of and apparatus for making a magnetic recording medium, a plurality of rod-like orientation magnets are positioned in spaced relation in the movement direction of a non-magnetic substrate so that the magnetic pole facing the non-magnetic substrate is different between adjacent orientation magnets and the orientation magnets are oblique with respect to the substrate movement direction and alternately point reversely. The spaces between the orientation magnets are adjusted so that the intensity of the magnetic field generated in the substrate movement direction between adjacent orientation magnets is 50 Oe or less. A magnetic coating composition is applied onto the non-magnetic substrate, and magnetic grains contained in the composition are randomly orientated by the orientation magnets.

Abstract: A flexible magnetic disc sheet is described, which has a central circular hole therein and has a protective layer only on a surface portion surrounding the edge of the central circular hole, the protective layer comprising (a) a radiation polymerized polymer of a compound which is polymerizable and hardenable by radiation and (b) a matting agent.