Hitachi, Ltd.

Fuzio Maeda

Heigo Ishihara

Akira Osaki

Waichi Nagashiro

Yoshiki Kato

Youichi Kawakubo

Eiichi Takasuna

Keigo Iechika

Masa-aki Imamura

A magnetic recording medium comprising a substrate and, formed thereon, a magnetic layer comprised of magnetic particles bonded to each other with a thermosetting binder can be improved with respect to the durability by forming a number of fine pores in the magnetic layer and impregnating the fine pores with a lubricant. Particularly, when the fine pores have a diameter of 0.2 .mu.m or less and a rate of the fine pore in area of 3 to 30%, the durability can be improved while maintaining the noise during the recording and reproduction of information on a low level. In preparing the magnetic recording medium having such fine pores, it is preferred that an easily thermal-decomposable additive, such as polyalkylene oxide, be added to a magnetic layer forming paint. A magnetic recording medium having further improved characteristics can be produced by interposing an undercoating layer having a number of fine pores between the magnetic layer and the substrate, allowing the fine pores in the undercoating layer to communicate with the fine pores in the magnetic layer and impregnating the fine pores with a lubricant. In this case, in forming the fine pores, it is preferable to add an easily thermal-decomposable additive to a paint or extract a thermoplastic resin from a layer containing the thermoplastic resin with a solvent.

Magnetic recording medium and method for producing the same

A magnetic recording medium comprising a substrate and, formed thereon, a magnetic layer comprised of magnetic particles bonded to each other with a thermosetting binder can be improved with respect to the durability by forming a number of fine pores in the magnetic layer and impregnating the fine pores with a lubricant. Particularly, when the fine pores have a diameter of 0.2 .mu.m or less and a rate of the fine pore in area of 3 to 30%, the durability can be improved while maintaining the noise during the recording and reproduction of information on a low level. In preparing the magnetic recording medium having such fine pores, it is preferred that an easily thermal-decomposable additive, such as polyalkylene oxide, be added to a magnetic layer forming paint. A magnetic recording medium having further improved characteristics can be produced by interposing an undercoating layer having a number of fine pores between the magnetic layer and the substrate, allowing the fine pores in the undercoating layer to communicate with the fine pores with a lubricant. In this case, in forming the fine pores, it is preferable to add an easily thermal-decomposable additive to a paint or extract a thermoplastic resin from a layer containing the thermoplastic resin with a solvent.

A magnetic recording medium of the present invention comprises: a substrate; a magnetic film formed on this substrate; and a nonmagnetic reinforcing agent mixed into the magnetic film and projected from the surface of the magnetic film. Assuming that the minimum flying height of the magnetic head which is lifted up over the magnetic film is h, a projection height T of the nonmagnetic reinforcing agent from the surface of the magnetic film satisfies the relation of h/4&lt;T&lt;h. By virtue of this, even if an amount of mixture of the nonmagnetic reinforcing agent which becomes a cause of the generation of the noises is reduced, the necessary durability can be obtained.

Magnetic recording medium

Growing community of inventors

Odawara, Japan

Fuzio Maeda