Magnetic recording mediums comprising a modified vinyl chloride resin binder in at least a magnetic recording layer

Claim 1

A magnetic recording medium which comprises a nonmagnetic support and a magnetic recording layer formed on one side of the support and made of a magnetic powder uniformly dispersed in a binder resin and having a size of from 0.01 to 0.5 micrometers, said binder resin comprising (a) a vinyl chloride resin consisting essentially of vinyl chloride units, from 0.1 to 4.0 weight percent of an --SO 3 M group or --OSO 3 M group, in which M represents a monovalent metal or a NH 4 group, and from 0.5 to 40 weight percent of an epoxy group in the molecule, said vinyl chloride resin having an average degree of polymerization of from 200 to 600 and being used in an amount of from 10 to 40 parts by weight per 100 parts by weight of said magnetic powder, and (b) at least one member selected from the group consisting of fatty acids having a saturated or unsaturated hydrocarbon group containing from 8 to 18 carbon atoms, fatty acid esters of fatty acids having a saturated or unsaturated hydrocarbon group containing from 8 to 18 carbon atoms and fatty alcohols having a saturated or unsaturated hydrocarbon group containing from 3 to 12 carbon atoms, and phosphoric acid esters of the following formulae ##STR2## in which each R represents a saturated or unsaturated hydrocarbon group having from 3 to 16 carbon atoms, said at least one member being used in an amount of from about 0.1 to 10 parts by weight per 100 parts by weight of the magnetic powder and from about 1 to 25 parts by weight per 100 parts by weight of the vinyl chloride resin.