The B. F. Goodrich Company

Kyowa Hakko Kogyo Co., Ltd.

Kyowa Yuka Co., Ltd.

Shinichiro Jimbo

Yorozu Yokomori

Shigeo Hosokawa

Masahiko Yasuda

Ikuo Shimizu

Edmond G Kolycheck

Masanori Ikuta

Shoshiro Matsushita

Iwao Hotta

Izumi Itani

Dithiocarbonate composition

Compositions containing dithiocarbonate compound

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.

Magnetic coating formulations

Polyurethane resin containing a phosphoric acid group

Magnetic coating formulations and magnetic recording media

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.

Magnetic recording medium comprising a polyurethane resin coating

Growing community of inventors

Tokyo, Japan

Shinichiro Jimbo