Abstract: In a magnetic recording medium comprising a nonmagnetic substrate and at least one magnetic layer provided on the nonmagnetic substrate, in which layer a ferromagnetic fine powder and a binder are dispersed together, the magnetic layer comprises as a substantial binder a polyurethane obtained from a polyester polyol, a chain extender and an organic diisocyanate. The ferromagnetic fine powder contains cobalt-containing iron as a main component, and the polyurethane comprises a polyester polyol containing an aliphatic dibasic acid as a dibasic acid, and a diol component, at least 70 mol % of which contains an alkyl branched side chain having at least 2 carbon atoms.

Abstract: A poor solvent is used for removing low molecular weight components from a binder, which has weight average molecular weight within the range of 10,000 to 60,000, said poor solvent has a solubility parameter being different from solubility parameter of the binder by more than 1.3 and less than 2.3 and is a solvent such as acetonitrile having no active hydrogen, and a difference between solubility parameter of the solvent in the solution after mixing and solubility parameter of the binder is more than 1.0 and less than 2.0, said poor solvent is used for fractional precipitation, and the poor solvent being by 0.

Abstract: The present invention provides a magnetic recording medium having good electromagnetic transfer characteristics and high running durability, and it comprises a lower layer and a magnetic layer, said lower layer having at least one of magnetic powder or non-magnetic inorganic powder and a binder (A) dispersed therein and being placed on a non-magnetic support member, at least one layer of said magnetic layers having ferromagnetic powder and a binder (B) dispersed therein and being deposited on said lower layer, whereby said magnetic recording medium comprises polyurethane resins (1) and (2), said polyurethane resin (1) is contained as said binder (B) and comprises a short-chain diol having a cyclic structure and weight average molecular weight of 200 to 500 in an amount of 15 to 50 weight %, a polyol having an ether group of 1 to 6 mmol/g and weight average molecular weight of 500 to 5000 in an amount of 10 to 50 weight % in polyurethane, and an organic diisocyanate, and said polyurethane resin (2) is containe

Abstract: The present invention provides a magnetic recording medium, in which a binder does not migrates toward the surface of a magnetic layer and which has high durability. Said magnetic recording layer comprises at least one type or more of organic phosphorus compounds selected from the following formulae (1) to (3) and a binder, which contains an amino group or a quaternary ammonium base: ##STR1## where R represents substituted or non-substituted alkyl group, alkenyl group or aryl group, M represents hydrogen atom or alkali metal or ammonium, and n is 1 or 2.

Abstract: A magnetic recording medium comprises a magnetic layer containing a ferromagnetic powder, a binder and an abrasive material having a Mohs hardness of 8 or more on a non-magnetic support, wherein the average protrusion height, which represents the length between the central line of the surface roughness of the sectional curve of the magnetic layer and the upper end of the abrasive material existing (i) above the central line of the surface roughness of the magnetic layer and (ii) in the surface layer of the magnetic layer, is 15 nm or less.

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.