Fuji Photo Film Company, Limited

Shinobu Iida

Masaaki Fujiyama

Eiichi Tadokoro

Nobutaka Yamaguchi

Katsumi Ryoke

Toshimitu Okutu

Kenichi Masuyama

Keisuke Yamada

Shigeo Komine

Norio Nasu

Tadashi Ishikuro

Masahiro Utsumi

Takahito Miyoshi

Akira Kasuga

Yoshito Mukaida

Hiroshi Kato

Yasuhiro Abe

Naoki Sakai

Fumiaki Tsukuda

Masaaki Igarashi

A magnetic recording medium comprising a support having provided on one surface thereof a magnetic layer, and on the opposite surface thereof a backing layer comprising nonmagnetic particles dispersed in a binder, wherein the binder in the backing layer comprises a vinyl chloride-vinyl acetate copolymer of from 50 to 80 parts by weight, a polyester resin of from 1 to 40 parts by weight, and a polyisocyanate of from 10 to 49 parts by weight, per 100 parts by weight of the binder.

Magnetic recording medium and method for preparing the same

A method for preparing a magnetic recording medium comprising a non-magnetic support having thereon a magnetic layer comprised of ferromagnetic particles of hexagonal crystalline ferrite which comprises smoothing the surface of the magnetic layer and thereafter abrading the surface thereof by an abrasive tape.

Method for preparing a magnetic recording medium

A process for the preparation of a magnetic recording medium comprises the steps of subjecting a magnetic recording layer coated on a nonmagnetic support to surface smoothening treatment, said magnetic recording layer comprising a ferromagnetic powder dispersed in a binder, and then abrading a surface of the magnetic recording layer by means of an abrasive tape.

Process for the preparation of magnetic recording medium

A process for the preparation of a magnetic recording medium which comprises the steps of subjecting a magnetic recording layer coated on a nonmagnetic support to surface smoothening treatment, said magnetic recording layer comprising a ferromagnetic powder dispersed in a binder which is composed of a resin component and a curing agent, and then shaving a surface of said magnetic recording layer by means of a shaving device having high hardness.

A process for the preparation of a magnetic recording medium comprises the steps of subjecting a magnetic recording layer coated on a nonmagnetic support to surface smoothening treatment, the magnetic recording layer comprising a ferromagnetic powder dispersed in a binder, and then grinding both a surface of the magnetic recording layer and a surface of a back layer provided on the support using a specific grinder. The specific grinder is a fixed blade, a diamond wheel or a rotatable blade. A rotatable blade-grinder preferably employable for the grinding procedure comprises a rotatable body having a circular section and one or more blades provided on the periphery of the body.

A magnetic recording medium comprised of a nonmagnetic support base having a magnetic recording layer on one surface thereof and a backing layer on the other surface thereof is disclosed. The backing layer is comprised of (1) carbon black having a particle size in the range of 10 to 150 m.mu., (2) graphite having a particle size of 3.mu. or less, and (3) a curing agent. By utilizing this particular backing layer the resulting recording medium has improved durability with respect to the backing layer and shows a decreased in the number of dropouts and scratches during use.

Magnetic recording medium

A magnetic recording material, which comprises a non-magnetic support having provided on one side thereof a magnetic layer and on the other side thereof a backing layer is disclosed. The binder of the backing layer is comprised of a combination of a cellulose resin, a vinylidene chloride resin, a polyurethane resin and a polyisocyanate. Use of the backing layer increases the durability of the tape and aids in preventing drop out.

A magnetic recording material, which comprises a magnetic layer coated on a non-magnetic support is disclosed. The magnetic layer contains both carbon black fine powder having a mean primary grain size of less than 10 m.mu. and carbon black coarse powder having a mean primary grain size in the range of 50 to 120 m.mu. in a mixing ratio ranging from 95/5 to 5/95. The material is improved in both RF output and audio output.

Magnetic recording material

A magnetic recording medium is disclosed which comprises a non-magnetic support having provided thereon a magnetic recording layer consisting ferromagnetic powder and containing graphite and a fatty acid ester.

A magnetic recording medium comprising a support having provided thereon a magnetic recording layer containing (1) a cobalt-containing iron oxide, (2) graphite, and (3) a copolymer of vinyl chloride, vinyl acetate and maleic acid.

A magnetic recording medium comprised of a non-magnetic support base having provided thereon a magnetic recording layer is disclosed. The medium also has position thereon a compound selected from the group consisting of carboxylic acids and carboxylic acid derivatives, the compound being present on an edge portion of the medium. The medium also includes an additional lubricant on the middle part of the medium, the additional lubricant being selected from the group consisting of alphatic acid esters, alphatic acids, silicons and phosphoric acid esters. By utilizing two different types of lubricants on different portions of the medium it is possible to obtain improved lubricating properties and thus improve runnability with respect to the operation of the magnetic recording medium.

A magnetic recording medium comprised of a support base having a magnetic recording layer positioned thereon is disclosed. The recording medium has positioned an aliphatic acid ester compound on an edge portion of the surface of the recording layer. By utilizing the aliphatic acid ester the recording medium has less audio output variation and the tracking control of the medium is improved. Further, the medium has good running characteristics and excellent sensitivity.

A magnetic recording material comprised of a non-magnetic support base having provided thereon a magnetic recording layer on one side and the back layer on the other side is disclosed. The magnetic recording layer is comprised of ferromagnetic particles dispersed in a binder in combination with carbon black particles having an average primary particle size of 30 .mu.m or less. The back layer is comprised of a binder having dispersed therein carbon black having an average primary particle size in the range of 50 to 150 m.mu.. The magnetic recording material has improved electromagnetic properties and improved durability, particularly with respect to video S/N and dropout.

Magnetic recording materials

A magnetic recording medium is disclosed. The medium is comprised of a non-magnetic support having coated thereon a magnetic recording layer and a backing layer on the surface opposite the magnetic recording layer. The backing layer contains carbon black and the surface treated calcium carbonate dispersed in a binder. The calcium carbonate is surface treated so as to make the particles hydrophobic. Including the carbon black and the calcium carbonate in the backing layer provides a recording medium with improved durability and a reduced amount of drop out.

In a magnetic recording substance comprising a non-magnetic support and a magnetic recording layer provided on the support, carbon black having a surface area of at least 700 m.sup.2 /g and an oil absorption of at least 300 ml (DBP)/100 g is contained in the magnetic layer thereby lowering the surface electric resistance without deteriorating the characteristics of the magnetic recording layer.

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Kanagawa, Japan

Shinobu Iida