Fuji Photo Film Company, Limited

Masaaki Suzuki

Ryuji Shirahata

Tatsuji Kitamoto

Yasuo Tamai

Masashi Aonuma

Shin-ichiro Dezawa

Hiroshi Ogawa

Kengo Oishi

Yasuyuki Yamada

Osamu Suzuki

Goro Akashi

Akira Kasuga

Chiaki Mizuno

Noburo Hibino

Kouichi Masaki

Koh Kamada

Hiroshi Amari

Satoshi Sakakibara

A magnetic recording medium is disclosed which comprises a non-magnetic support having coated thereon two magnetic layers, wherein an under layer of the magnetic layers contains ferromagnetic metal particles having a coercive force of 550 to 700 Oe, and wherein an upper layer of the magnetic layers contains a ferromagnetic particles having a specific surface area determined by the BET method of 25 to 35 m.sup.2 /g, a coercive force of 700 to 800 Oe and a thickness of 0.5 to 2.5 .mu.m, wherein the entire magnetic layer including the upper layer and the under layer have a coervice force of 580 to 750 Oe, a residual magnetic flux density of 2200 to 3200 gauss and a thickness of 3.0 to 5.0 .mu.m.

Magnetic recording medium

Magnetic recording medium is disclosed which comprises a non-magnetic support having coated thereon a magnetic layer mainly containing ferromagnetic metal particles and a binder:

A compact magnetic tape cassette suitable for digital recording in which dust is prevented from entering the cassette and contaminating the tape held therein. Slide grooves are formed in upper and lower walls of the case of the cassette, behind a central opening and side openings on either side of the central opening. Slidable guard panels which slide to close the central opening and the side openings and which are substantially U shaped in section have slides which are engaged with the slide grooves. Each of the guard panels has a through-hole in the front wall thereof which is slidable to open the respective side opening when the guard panels are urged against compression springs arranged on side portions of the front wall of the cassette case. The cassette is symmetrical in configuration.

Magnetic tape cassette

A magnetic recording medium comprising a nonmagnetic base having formed thereon a magnetic layer containing a fine particulate ferromagnetic material dispersed in a binder is disclosed. The ferromagnetic material is a mixture of two fine ferromagnetic powders (a) and (b) in a weight ratio of from 90/10 to 30/70. The powder (a) comprises .gamma.-Fe.sub.2 O.sub.3 particles having a coercivity (Hc) of 330 to 390 Oe and a saturation magnetization (.sigma.s) of 68 to 80 emu/g at a maximum magnetizing force (Hm) of 5 KOe, and a specific surface area of 18 to 25 m.sup.2 /g, and powder (b) comprises .gamma.-Fe.sub.2 O.sub.3 particles having a coercivity (Hc) of 400 to 450 Oe and a saturation magnetization (.sigma.s) of 65 to 78 emu/g at a maximum magnetizing force (Hm) of 5 KOe, and a specific surface area of 22 to 30 m.sup.2 /g. The tape has the ability to clearly and faithfully reproduce high fidelity sound.

A process for the production of a magnetic recording member which comprises effecting electric field vapor deposition under conditions such that the angle of incidence at which the vapor beam of a ferromagnetic metal strikes a support is at least about 50.degree. and the electric field between the support and a vaporization source is at least about 5 kv/m.

Process for the production of magnetic recording members

A magnetic audio-recording tapes based on finely-divided ferromagnetic alloy materials are disclosed which have improved surface characteristics. The improvement of recording and playback characteristics is specifically exhibited in a reduction in modulation noise.

Magnetic audio-recording tape

A magnetic recording tape comprising a non-magnetic support having thereon a dual layer magnetic recording coating comprising ferromagnetic particles dispersed in a binder, wherein the fine ferromagnetic particles of the outer layer are a mixture of two or more kinds of fine ferromagnetic particles having two or more peaks in the coercive force distribution and said particles containing at least one kind of fine ferromagnetic alloy particles and the fine ferromagnetic particles of the inner layer being ferromagnetic iron oxide particles having peaks in the coercive force distribution lower than the minimum peaks in the coercive force distribution of the ferromagnetic particles of the outer layer, with the thickness of the outer layer not being greater than the thickness of the inner layer.

Multilayer magnetic recording medium

A magnetic recording medium excellent in adhesiveness and surface property is produced by a process comprising treating the surface of a plastic substrate by glow discharge, then subjecting the substrate to a surface activating treatment and forming a magnetic metallic plating layer on the surface of the substrate by an electroless plating method.

Process for the production of a magnetic recording medium

In a magnetic recording tape having a total thickness of 4.0 to 14.5 microns, the base thickness to magnetic layer thickness ratio is from 2:3 to 3:2, the base Young's modulus to magnetic layer Young's modulus ratio is from 1:2 to 2:1 and the tensile strength at 0.5% elongation is .sqroot.d/16 Kg or more to the total thickness d (micron).

Magnetic recording tape

This invention relates to a magnetic recording medium which comprises a non-magnetic support, at least one magnetic recording layer containing a magnetic powder and a binder and being provided on the support and a ferromagnetic metal thin film with a thickness of at most 1 micron, being provided on the magnetic recording layer by an oblique incidence vapor deposition method with an electric field. This multi-layer magnetic recording medium exhibits various excellent magnetic recording performances.

This invention relates to a magnetic recording medium comprising a ferromagnetic metal thin film as a magnetic recording layer on a non-magnetic flexible support, in which the surface roughness of the support is 0.10 .mu.m or less and the period of the surface roughness is v/10.sup.6 .mu.m or less where v represents a relative speed between a magnetic head and magnetic recording medium by .mu.m/sec. In the case of providing an undercoated layer between the magnetic recording layer and non-magnetic flexible support, the surface roughness of the undercoated layer is adjusted to 0.10 .mu.m or less and the period of the surface roughness is adjusted to v/10.sup.6 .mu.m or less.

Recording method employing a magnetic recording medium

The process for the production of a magnetic recording medium by electroless plating comprises carrying out the plating in a plating aqueous solution containing at least one ferromagnetic metal ion, barium ion and hypophosphite ion as a reducing agent, and thus forming a magnetic metal thin film.

This invention relates to a method of forming a metallic thin film on a plastic substrate by electroless plating, which comprises providing an undercoated layer consisting essentially of polyvinylidene chloride or vinylidene chloride copolymer on the surface of the plastic substrate and then subjecting to a surface activating treatment and electroless plating.

Method of forming a metallic thin film by electroless plating on a

An improved method of making a magnetic recording material comprises providing a ferromagnetic metal thin layer which has uniaxial anisotropy in any direction on a web by means of plating. A plating solution is jetted onto the web through holes in a conveying pipe set in a plating bath. The web is then moved from the vicinity of the conveying pipe by the spouting force of the plating solution, and then conveyed along a helical path about the conveying pipe without contacting the surface of conveying pipe. Plating occurs while applying a magnetic field to the web.

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Odawara, Japan

Masaaki Suzuki