Polyurethane resin containing a phosphoric acid group

摘要

A polyurethane resin is synthesized from a reaction mixture of at least one phosphorus compound, an epoxy compound, a polyisocyanate, a polyfunctional hydroxy compound, and optionally a chain extender. The polyurethane resin contains one phosphoric acid group or one residual group derived from phosphoric acid per 3,000 to about 200,000 number average molecular weight of the polyurethane resin. The weight average molecular weight of the polyurethane resin is from about 10,000 to about 250,000. A magnetic coating formulation is comprised of principally of magnetic particles and a binder. A magnetic recording media comprises a laminate as in the form of a magnetic layer composed principally of magnetic particles and a binder wherein at least a portion of the binder is the polyurethane resin. The substrate of the magnetic recording medium is a suitable polymer such as polyester, and the like. The utilization of the polyurethane resin containing a phosphorus compound therein results in excellent dispersion of the magnetic particles as well as exceptional durability.