| 摘要 |
PURPOSE:To obtain a magnetic recording medium which excels in the surface properties, the dispersion properties and the electromagnetic conversion characteristics, by using a polyvinyl chloride copolymer obtained by copolymerizing a polymeric monomer containing a metal sulfonate group to a binder of a magnetic layer. CONSTITUTION:A polyvinyl chloride copolymer is obtained by copolymerizing a polyvinyl chloride monomer, a polymeric monomer containing a metal sulfonate group and another copolymerizable monomer when necessary by copolymerization processes such as the emulsion polymerization, solution polymerization, suspension polymerization, block polymerization, etc. As a metal of a metal sulfonate group, an alkali metal, especially preferably sodium, potassium and lithium may be preferably used. As a polymerizable monomer containing a metal sulfonate group, CH2-CH-CO3M, CH2-CH-CH2-CH-CH2-SO3M, etc. are mentioned. Then the quantity of the monomer containing a metal sulfonate group is preferably set at 0.1-10mol% for the polyvinyl chloride copolymer.
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