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Magnetic recording medium

  • US 20080057351A1
  • Filed: 03/29/2007
  • Published: 03/06/2008
  • Est. Priority Date: 03/29/2006
  • Status: Abandoned Application
First Claim
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1. A magnetic recording medium, which comprises:

  • a backcoat layer comprising a first binder;

    a nonmagnetic support;

    a nonmagnetic layer comprising a nonmagnetic powder and a second binder; and

    a magnetic layer comprising a ferromagnetic powder and a third binder, in this order, wherein the backcoat layer has a glass transition temperature of from 65 to 95°

    C., and the first binder satisfies all of the following requirements (1) to (5);

    (1) the first binder comprises a vinyl chloride-based resin and a polyurethane resin as main components;

    (2) the vinyl chloride-based resin has a solubility parameter of from 9 to 11 (cal·

    cm

    3
    )1/2, a glass transition temperature of from 65 to 95°

    C. and a weight-average molecular weight of from 5000 to 25000;

    (3) a ratio of the vinyl chloride-based resin to the total mass of the vinyl chloride-based resin and the polyurethane resin is from 10 to 60% by mass;

    (4) the polyurethane resin has a solubility parameter of from 9.5 to 11.5 (cal·

    cm

    3
    )1/2, a glass transition temperature of from 80 to 110°

    C. and a weight-average molecular weight of from 20000 to 60000; and

    (5) a ratio of the polyurethane resin to the total mass of the vinyl chloride-based resin and the polyurethane resin is from 90 to 30% by mass.

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