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AssigneesKyowa Hakko Kogyo Co., Ltd., The B. F. Goodrich Company
InventorsMasahiko Yasuda, Shigeo Hosokawa, Yorozu Yokomori, Shinichiro Jimbo
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A magnetic coating formulation is composed principally of magnetic particles and a binder. At least a portion of the binder is a polyurethane resin synthesized from a reactant mixture of specific phosphorus compound, epoxy compound, isocyanate compound and polyfunctional hydroxy compounds. The reactant mixture may optionally contain a chain extender. The polyurethane resin contains one phosphoric acid group or one residual group derived from phosphoric acid per 3,000-200,000 number average molecular weight of the polyurethane resin, and has a number average molecular weight of 4,000-150,000. A magnetic recording medium with a magnetic coating layer formed from the magnetic coating formulation is also disclosed. The magnetic coating layer features not only excellent dispersion of magnetic particles, in other words, excellent magnetic characteristics but also superb durability.
A polyurethane resin synthesized from a reactant mixture of components (1), (2), (3) and (4) set out below, containing one phosphoric acid group or one residual group derived from phosphoric acid per 3,000-200,000 number average molecular weight of the polyurethane resin, and having a number average molecular weight of 4,000-150,000;
The polyurethane resin according to clam 8, wherein said phosphorus compound is phenylphosphonic acid or octylphosphonic acid, wherein said epoxy compound is a bisphenol A-ephichlorohydrix epoxy resin, a phenolic novolak epoxy resin, or an cresolic novolak epoxy resin, wherein said isocyanate is MDI, and wherein said polyfunctional hydroxy compound is a polybutylene adipate polyol.
Dependencies are inferred from the claim text.