Abstract: A magnetic recording medium comprising a nonmagnetic support having provided thereon a magnetic layer comprising a ferromagnetic powder dispersed in a binder, wherein said ferromagnetic powder has a specific surface area of 40 m.sup.2 /g or more as measured by the BET method; said magnetic layer further comprises Al.sub.2 O.sub.3 particles having an average particle diameter of from about 0.1 to 0.5 .mu.m; and said binder comprises the combination of (1) a vinyl chloride resin containing a phosphate ester group represented by ##STR1## wherein M.sub.1 and M.sub.2, which may be the same or different, each represents Na, K, Li, H, N.sym.R.sub.3, or N.sym.HR.sub.2 wherein R represents an alkyl group or a hydrogen atom, and (2) at least one resin other than said vinyl chloride resin containing at least one of --SO.sub.3 M, --OSO.sub.2 M, --COOM, and ##STR2## wherein M, M.sub.1, and M.sub.2, which may be the same or different, each represents Na, K, Li, H, N.sym.R.sub.3, or N.sym.HR.sub.

Abstract: A method for making a magnetic recording medium comprises the steps of mixing ferromagnetic grains and a surface treating agent, grinding the resulting mixture, and thus obtaining a ground mixture. A binder and a solvent are added to the ground mixture, which results from the mixing and grinding process, the resulting mixture is kneaded and diluted, and a kneaded and diluted mixture is thus obtained. An additive and a solvent are then added to the kneaded and diluted mixture, which results from the kneading and diluting process, a dispersion process is carried out on the resulting mixture, and a dispersion mixture is thereby obtained. Thereafter the dispersion mixture, which results from the dispersion process, is applied to a non-magnetic substrate.

Abstract: A magnetic recording medium comprising a non-magnetic support having provided thereon a magnetic layer comprising a ferromagnetic powder dispersed in a binder,wherein said binder comprises a polymer containing a polar group selected from --SO.sub.3 M, --OSO.sub.3 M, --COOM, ##STR1## where M represents a hydrogen atom, Li, Na, K or NR.sub.4 where R represents a hydrogen atom or an alkyl group, and M' represents a hydrogen atom, Li, Na, K, an alkyl group or NR.sub.4 where R represents a hydrogen atom or an alkyl group, andsaid magnetic layer contains at least one fatty acid ester compound represented by formula (I), at least one fatty acid ester compound represented by formula (II), and at least one fatty acid having from 11 to 35 carbon atoms: ##STR2## wherein R.sup.1 represents a linear or branched chain hydrocarbon group having from 11 to 35 carbon atoms, R.sup.

Abstract: A magnetic recording medium comprising a nonmagnetic support and a magnetic recording layer provided on said support, in which said magnetic recording layer comprises:a ferromagnetic metal powder having a specific surface area of not less than 40 m.sup.2 /g;a fatty acid having a melting point of lower than 50.degree. C.;a fatty acid having a melting point of not lower than 50.degree. C.; anda fatty acid ester.

Abstract: A magnetic recording medium comprising a non-magnetic support having thereon a magnetic layer containing (a) ferromagnetic particles, (b) a binder containing at least one resin substituted with at least one polar group selected from an --SO.sub.3 M group, a --COOM group, an --OSO.sub.3 M group, an ##STR1## group and a ##STR2## group, wherein M represents H, Li, Na or K and M' represents H, Li, Na, K or an alkyl group, and (c) at least one fatty acid lubricating agent comprising at least one fatty acid derivative represented by formula (I): ##STR3## in which R represents a hydrocarbon group having from 11 to 21 carbon atoms, X represents hydrogen or a methyl group, R' represents a hydrocarbon group having from 1 to 8 carbon atoms and n is an integer of from 2 to 20.

Abstract: A magnetic recording medium is described, comprising a non-magnetic support having provided thereon, in sequence, an intermediate layer and a magnetic layer coated with a dispersion of ferromagnetic particles in a binder, wherein said intermediate layer contains at least one binder containing at least one of a hydroxyl group and an amino group, and said magnetic layer contains an isocyanate compound.

Abstract: A magnetic recording medium comprising a nonmagnetic support and a magnetic recording layer provided on said support, in which said magnetic recording layer comprises:a ferromagnetic metal powder having a specific surface area of not less than 40 m.sup.2 /g andan abrasive having a Mohs' scale of hardness of not less than 6,both being dispersed in a binder containing a polycarbonate-polyurethane.

Abstract: A magnetic recording medium contains in its magnetic recording layer a ferromagnetic metal powder containing an aluminum component in an amount of 1 to 6% by weight as alumnum metal, and an extremely hard abrasive such as .alpha.-alumina, chrome oxide, silicon carbide and silicon nitride. A magnetic recording medium preferably contains in its magnetic recording layer a binder comprising a resin component having a polar group.

Abstract: In a magnetic recording medium such as a video tape comprising a nonmagnetic support and a magnetic recording layer provided on the support, said magnetic recording layer comprising a binder and a ferromagnetic powder dispersed therein, the improvement in which:the magnetic recording layer comprises a fatty acid ester lubricant and a lubricant other than the fatty acid ester lubricant;the binder is composed of a resin component comprising a resin containing a repeating unit which has a polar group and having a glass transition point of not lower than 50.degree. C., and a resin containing a repeating unit which has a polar group and having a glass transition point of lower than 50.degree. C; andat least one resin of the resins contains a repeating unit having a polar group such as --SO.sub.3 M, --OSO.sub.3 M or --PO(OM').sub.2, wherein M is hydrogen or an alkali metal atom, and M' is hydrogen, an alkali metal atom or a lower hydrocarbon group.

Abstract: A magnetic recording medium comprising a nonmagnetic support and a magnetic recording layer provided on the support, said magnetic recording layer comprising a binder and a ferromagnetic powder dispersed therein, which is characterized in that said binder is composed of a resin component comprising:a vinyl chloride copolymer containing a repeating unit having at least one polar group selected from the group consisting of --SO.sub.3 M, --OSO.sub.3 M, --COOM and --PO(OM').sub.2, wherein M is hydrogen or an alkali metal atom, and M' is any one of hydrogen, an alkali metal atom and a lower hydrocarbon group, and a repeating unit having an epoxy group; anda polyurethane resin containing a repeating unit having at least one polar group selected from the group consisting of --SO.sub.3 M, --OSO.sub.3 M, --COOM and --PO(OM').sub.2, wherein M and M' have the same meanings as defined above.

Abstract: A magnetic recording medium comprises a non-magnetic support having provided thereon a magnetic layer containing magnetic particles dispersed in a binder. The magnetic layer contains acicular Cr.sub.2 O.sub.3 having an average length in the long axis of 1.0 .mu.m or less, an average length in the short axis of 0.1 .mu.m or less and an acicular ratio (long axis/short axis) of from 5/1 to 20/1 in an amount of from 1 to 20 wt % based on the total weight of the magnetic particles. The binder comprises at least one material selected from the group consisting of polyurethane having a glass transition temperature (Tg) of from 0.degree. to 95.degree. C. or containing a metal sulfonate group, or a vinyl chloride resin containing a metal sulfonate group.

Abstract: A magnetic recording media comprising a nonmagnetic supporting substrate and a ferromagnetic alloy powder-containing magnetic layer applied onto the surface thereof is produced by:pre-dispersing a ferromagnetic alloy powder with and in a binder, said alloy having a specific surface area (S.sub.BET) of no less than 45 m.sup.2 /g and an absorbed water content of no higher than 1.2% by weight resulting in a pre-dispersion;mixing and dispersing an additional binder with and in the pre-dispersion; andcoating the resultant mixed and dispersed magnetic coating liquid onto said nonmagnetic supporting substrate.

Abstract: A magnetic recording medium such as a video tape comprising a magnetic recording layer which comprises a ferromagnetic metal powder having a specific surface area of not less than 42 m.sup.2 /g and an inorganic material powder having a Mohs' scale of hardness of not less than 5, wherein at least 90 wt. % of said inorganic material powder consists of particles having a particle size of 0.1-0.6 .mu.m, 51-85 wt. % of a portion of said particles consisting of particles having a particle size of less than 0.3 .mu.m, and the residual portion consisting of particles having a particle size of not less than 0.3 .mu.m.

Abstract: A magnetic recording medium is disclosed which comprises a non-magnetic support having provided thereon a magnetic layer containing ferromagnetic metal particles and a binder, wherein the ferromagnetic metal particles have a specific surface area of 30 m.sup.2 /g or more, and a saturation magnetization of 120 emu/g or more and have been surface-treated with an organic compound. Also, a magnetic recording medium is disclosed which comprises a non-magnetic support having provided thereon a magnetic layer containing ferromagnetic particles and a binder, wherein the ferromagnetic particles have been surface-treated with an organic compound and the binder has essentially no functional groups which adsorb onto ferromagnetic metal particles.

Abstract: A magnetic recording medium comprising a nonmagnetic supporting substrate and a magnetic layer provided thereon by a binder, said magnetic layer contains a ferromagnetic alloy powder having a specific surface area (S.sub.BET) of no less than 45 m.sup.2 /g, and copper oleate in an amount of no less than 0.001 part by weight per 100 parts by weight of said ferromagnetic alloy powder.

Abstract: A magnetic recording medium is described, comprising a non-magnetic support having provided thereon a magnetic layer comprising ferromagnetic particles dispersed in a binder, said ferromagnetic particles having a BET specific surface area of 25 m.sup.2 /g or more, said binder comprising a modified polyurethane resin containing 0.1 meq/g or more of functional groups selected from carboxyl groups, hydroxyl groups, sulfonic acid groups, and epoxy groups, and containing at least three functional groups per molecule of the resin.

Abstract: A process for preparing a ferromagnetic metal powder and a magnetic recording medium utilizing that powder are disclosed. The ferromagnetic metal powder is prepared by heat-treating an acicular iron oxyhydroxide or an acicular iron oxide powder prepared from the acicular iron oxyhydroxide in a non-reducing gas at a temperature of from 300.degree. C. to 1000.degree. C. or in a reducing gas at a temperature of from 150.degree. C. to 500.degree. C. The heat-treated material is washed and then reduced under heating. The ferromagnetic metal powder prepared in this manner is dispersed in a binder and cated on a non-magnetic base to form a magnetic recording medium. By utilizing the washing step followed by heat-treating preparing the ferromagnetic metal powder a large amount of water soluble impurities are removed from the metal powder. The metal powder produced according to this disclosed process as excellent oxidation stability and ability to resist corrosion.

Abstract: Ferromagnetic metal particles are disclosed, which have a silane compound on the surface thereof. The silane compound is represented by the formula:R.sub.n --Si--(OR').sub.4-nwherein R and R' each represent an alkyl group and n represents 2 or 3. The ferromagnetic metal particles have excellent oxidation stability and corrosion resistance. Furthermore, the ferromagnetic metal particles have good dispersibility within a binder when used in connection with producing a magnetic recording medium.

Abstract: A magnetic recording medium is disclosed. The medium is comprised of a support having a magnetic layer coated thereon. The magnetic layer is comprised of a ferromagnetic metal powder and a binder. The ferromagnetic metal powder has a specific surface area of not less than 30 m.sup.2 /g. The magnetic layer is further comprised of a fatty acid and a fatty acid ester in a total amount of 2 to 10 wt % based on the weight of the ferromagnetic metal powder. The proportion of the fatty acid ester is 15 to 60 wt % based on the total weight of the fatty acid and the fatty acid ester. The surface roughness of the magnetic layer is not more than 0.03.mu..

Abstract: A magnetic recording medium comprising a non-magnetic base and an overlying magnetic coating having ferromagnetic particles dispersed in a binder is disclosed. The magnetic coating is characterized by further containing a titanate coupling agent.