Tdk Electronics Company, Limited

Takehisa Ohkawa

Kuniichi Yoda

Hitoshi Azegami

Masahiro Takizawa

Kuniichi Shinomiya

A magnetic recording medium is provided which is assured of smoothly and stably running properties and is free of the so-called 'squeal' phenomenon, especially in an environment of high temperature and high humidity. A highly viscous silicone oil having a viscosity of 100,000 or more is incorporated as a lubricating agent in the magnetic coating of the magnetic recording medium in an amount of 0.5 to 2% by weight based on binder. Such silicone oil is a dimethyl silicone oil having the following rational formula: ##STR1## where n is a number which determines a viscosity thereof.

Magnetic recording medium

A magnetic recording medium is provided which has smooth and stable running performances and is free of 'squeal' phenomenon, especially in an environment of high temperature and high humidity. A highly viscous silicone oil having a viscosity of 100,000 centistokes or more is incorporated in combination with a higher fatty having a melting point of 44.degree. C. or more into a magnetic coating layer of the magnetic recording medium. Such silicone oil is represented by the general formula: ##STR1## wherein R is CH.sub.3, R' is CH.sub.3, C.sub.6 H.sub.5 or F and n is a number which determines a viscosity thereof. Such higher fatty acid is selected from lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, behenic acid and the like.

A magnetic recording medium is provided which has smooth and stable running performances and is free of 'squeal' phenomenon, especially in an environment of high temperature and high humidity. A highly viscous silicone oil having a viscosity of 100,000 centistokes or more is incorporated in combination with a higher fatty acid ester composed of a higher fatty having a melting point of 44.degree. C. or more and a monohydric alcohol containing 3 to 8 carbon atoms into a magnetic coating layer of the magnetic recording medium. Such silicone oil is represented by the general formula: ##STR1## wherein R is CH.sub.3, R' is CH.sub.3, C.sub.6 H.sub.5 or F and n is a number which determines a viscosity thereof. Such higher fatty acid ester is selected from butyl myristate, butyl palmitate, propyl stearate, butyl stearate and the like.

A magnetic recording medium is provided which has smooth and stable running performances and is free of 'squeal' phenomenon, especially in an environment of high temperature and high humidity. A highly viscous silicone oil having a viscosity of 100,000 centistokes or more is incorporated in combination with a higher fatty acid glycerine ester composed of a higher fatty acid having a melting point of 44.degree. C. or more and glycerine into a magnetic coating layer of the magnetic recording medium. Such silicone oil is represented by the general formula: ##STR1## wherein R is CH.sub.3, R' is CH.sub.3, C.sub.6 H.sub.5 or F and n is a number which determines a viscosity thereof. Such higher fatty glycerine ester is selected from monoglyceride of myristic acid, monoglyceride of palmitic acid, monoglyceride of stearic acid, monoglyceride of oleic acid and the like.

A magnetic recording medium is provided which has smooth and stable running performances and is free of 'squeal' phenomenon, especially in an environment of high temperature and high humidity. A highly viscous silicone oil having a viscosity of 100,000 centistokes or more is incorporated in combination with a sorbitan fatty acid ester into a magnetic coating layer of the magnetic recording medium. Such silicone oil is represented by the general formula: ##STR1## wherein R is CH.sub.3, R' is CH.sub.3, C.sub.6 H.sub.5 or F and n is a number which determines a viscosity thereof. Such sorbitan fatty acid ester is selected from sorbitan monopalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate and the like.

A magnetic recording medium comprises a substrate coated with a magnetic layer comprising a magnetic powder and a binder comprising an urethane resin and a vinyl chloride-vinyl acetate-maleic acid copolymer having a content of maleic acid component of at least 1.5%.

A magnetic recording medium comprises a substrate coated with a magnetic layer comprising a magnetic powder and a binder comprising an urethane resin or a polyester and a vinyl chloride type copolymer of vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer or vinyl chloride-vinylidene chloride copolymer having a polymerization degree of up to 300.

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Usuda, Japan

Takehisa Ohkawa