PURPOSE: To obtain a medium having excellent magnetic characteristics, durability, etc. by dispersing magnetic powder into a binder consisting of a copolymer of specific 5 kinds of monomers having a specific OH/CH absorption ratio of the IR absorption spectra thereof or above, a specific polyurethane resin and polyisocyanate.
CONSTITUTION: The magnetic powder is dispersed into the binder contg. the copolymer which is the copolymer of 50W85wt% (hereafter weight is abbreviated) vinyl chloride, 5W40% vinyl ester alkyl carboxylate, 1.0W5.0%, for example, maleic acid, (meth)acrylic acid and the ester thereof, etc. copolymerizable with vinyl chloride and which has ≥0.2 absorption ratio of OH/CH of the IR absorption spectra, the polyurethane resin (PU) having about 10W1,000g equiv./104g -SO3M (M is an alkali metal) is the molecule and the polyisocyanate (PI) resin within the range of 20W80% PU and 5W30% PI with respect to the total resin- component in the binder. The magnetic recording medium which is uniformly dispersed with the magnetic powder and has good preserving property at and under a high temp. and high humidity and stability is thus obtd.
ISHIHARA YUJI
AZEGAMI HITOSHI
