Abstract: This invention permits formation of a magnetic coating excelling in the degree of orientation in spite of a decrease in the thickness thereof and ensures impartation of a high degree of packing and high durability to the magnetic layer of a small thickness because of the infallible presence of a backcoat layer in an undried state (particularly a wet state) while the magnetic layer is in an undried state (particularly a wet state). It also allows efficient formation of a backcoat layer which used to impose a heavy load on the conventional process of manufacture. Preferably, this invention has the calendering work performed in the in-line system such that the surface quality of the magnetic layer may be exalted by improving the operational efficiency of the calendering step and, as a result, the loss of the applied layer of the paint which used to occur during the course of the calendering step in the conventional separate line may be decreased.

Abstract: A magnetic recording medium having excellent electromagnetic characteristics and running durability includes a non-magnetic support and a magnetic layer formed thereon which is composed mainly of a magnetic powder and a binder, the binder being a mixture ofi) a vinyl chloride copolymer having amine-modified vinyl units and acidic functional group-containing vinyl units in a molecule,ii) a polyurethane resin having a glass transition temperature (Tg) of -50.degree. C. to 0.degree. C. (Tg 1), andiii) a polyurethane resin having a glass transition temperature (Tg) of higher than 0.degree. C. to 80.degree. C. (Tg 2).

Abstract: A magnetic recording medium having good dispersibility, dispersion stability of a magnetic paint and electromagnetic characteristics, and excellent running durability and still characteristics, comprises a non-magnetic support and a magnetic layer formed thereon which is mainly composed of a magnetic powder and a binder, wherein said binder is a mixture ofi) a vinyl chloride copolymer having amine-modified vinyl units and acidic functional group-containing vinyl units in a molecule,ii) a polyurethane resin having a number average molecular weight of 5000 to 25000 (Mn 1), andiii) a polyurethane resin having a number average molecular weight of higher than 25000 to 100000 (Mn 2).

Abstract: The magnetic recording medium of this invention comprises a magnetic layer formed on one of the opposite surfaces of a nonmagnetic support and a backcoat layer using a nonmagnetic powder and a binder as main components thereof and formed on the other surface thereof and uses as the binder in the backcoat layer a vinyl chloride-based copolymer having an amine-modified vinyl unit and an acidic functional group-containing vinyl unit. Owing to this construction, a paint to be used therein realizes perfect dispersibility and perfect stability. As a result, the backcoat layer to be formed therein is enabled to acquire excellent surface properties and the magnetic recording medium to be finally produced is allowed to exhibit an excellent electromagnetic conversion property.

Abstract: A magnetic recording medium includes a non-magnetic base film, and a magnetic layer on one surface thereof and a back coat layer on the other surface thereof. The back coat layer contains two kinds of carbon blacks varying in the average particle diameter, and a binder containing two kinds of copolymers. These two copolymers comprise vinyl chloride, alkylcarboxylic acid vinyl ester and vinyl alcohol, one being a copolymer A having an average polymerization degree of 300 to 600, and the other a copolymer B having an average polymerization degree of 200 to 800. This makes it possible to achieve a magnetic recording medium having a back coat layer, which is excellent in surface properties and electromagnetic characteristics, and has high running stability and durability.

Abstract: A first object of the invention is to provide a magnetic recording medium having minimized dropouts immediately after preparation, a reduced dropout increase and an electromagnetic property loss with the lapse of time, and good durability of coatings such as a magnetic layer. A second object is to provide a magnetic recording medium including a backcoat layer having high durability and antistatic effect in addition to the above advantages. A third object is to achieve a productivity increase and a cost reduction in the manufacture of such a magnetic recording medium.