Fuji Photo Film Company, Limited

Matsuaki Nakamura

Yasuo Tamai

Hiroshi Ogawa

Masashi Aonuma

Goro Akashi

Hiroshi Agawa

Tatsuji Kitamoto

Koshu Kurokawa

Kazuhide Ishii

A magnetic recording medium comprising a nonmagnetic support having thereon a magnetic recording layer of a ferromagnetic powder dispersed in a binder, wherein the ferromagnetic powder is a low vacuum evaporation process ferromagnetic metal powder subjected to a surface oxidation stabilizing processing and the low vacuum evaporation process ferromagnetic metal powder is one processed with an aqueous solution containing at least one anionic surface active agent.

High density magnetic recording media

A magnetic recording medium comprising a non-magnetic support having thereon a magnetic recording layer containing a finely divided ferromagnetic powder, a binder and at least one 1,2-epoxyalkane represented by the general formula (I) ##STR1## wherein R represents an alkyl group having 10 to 30 carbon atoms; in an amount of about 0.05 to about 3 parts by weight per 100 parts by weight of the ferromagnetic powder.

Magnetic recording medium

In a magnetic recording member comprising a non-magnetic support having provided thereon a magnetic layer comprising finely divided ferromagnetic powders dispersed in a binder, in which the binder comprises about 10 to about 70 wt% of (a) a polyester-polyurethane resin and about 30 to about 90 wt% of (b) a synthetic non-drying oil modified alkyd resin and (c) a polyisocyanate, wherein the molar ratio of the isocyanate groups present in the polyisocyanate (c) to the hydroxyl groups present in the synthetic non-drying oil-modified alkyd resin (b) ranges from about 0.8:1 to about 2.0:1. The binder system in accordance with the present invention provides excellent magnetic properties, particularly improved squareness ratio and 5 MHz output. The binder system of the present invention also enables the use of finely divided ferromagnetic alloy powders, with excellent magnetic properties being maintained when magnetic recording members are produced therefrom.

Magnetic recording member

A magnetic recording and reproducing apparatus provided with a magnetic head device comprising a supporting means having a recording magnetic head made of an alloy system magnetic material and a reproducing magnetic head made of a ferrite system magnetic material. The recording and reproducing heads are fixed relative to one another thereby eliminating the need for completely separate head mechanisms and for complex mechanisms to reliably interchange the positions of the two heads relative to the recording medium.

Magnetic recording and reproducing apparatus

A magnetic recording material, which comprises a non-magnetic support having thereon a magnetic layer containing ferromagnetic powder dispersed in a binder, with the magnetic layer containing an organic silicone compound represented by the following general formula (I); ##STR1## wherein R, R' and R', which may be the same or different, each has 7 to 21 carbon atoms and represents an alkyl group, an alkenyl group, an alkadienyl group, an alkatrienyl group or an alkatetraenyl group, m represents an integer of 1 to 100; n represents an integer of 0 to 250; and m+n.ltoreq.300 and m.gtoreq.n/5.

Magnetic recording material

A magnetic recording member comprising a non-magnetic support having thereon a magnetic layer of a ferromagnetic powder dispersed in a binder, wherein the magnetic layer contains an organic silicone compound represented by the formula (I): ##STR1## wherein R and R', which may be the same or different, each is a saturated or unsaturated hydrocarbon group containing 7 to 21 carbon atoms, and n is an integer of 0 to 50.

Magnetic recording members

A magnetic recording material comprising a non-magnetic flexible support having thereon a magnetic recording layer comprising a ferromagnetic powder dispersed in a binder, the surface of the non-magnetic flexible support having the magnetic recording layer thereon satisfying an S-factor expressed by the following relationship (I-1) ##EQU1## wherein S.sub.1 is the surface roughness in .mu.m of the surface of the non-magnetic flexible support having the magnetic recording layer thereon and d is the thickness in .mu.m of the magnetic recording layer, with the thickness (d) of the magnetic recording layer being about 5 .mu.m or less, and the back surface of the non-magnetic flexible support opposite that having the magnetic recording layer thereon satisfying an S-factor expressed by the following relationship (I-2) ##EQU2## wherein S.sub.2 is the surface roughness in .mu.m of the back surface of the non-magnetic support opposite that having the magnetic recording layer thereon and d is as described above.

A magnetic recording medium for high density recording comprising a support having thereon a magnetic recording layer comprising a ferromagnetic metal powder of the Fe-Co-Cr-B system and having a coercive force of about 700 to 1500 orsteds in the oriented direction of the magnetic substance and a residual magnetic flux density of about 1500 gauses or more, the residual magnetic flux density of which after storage for 160 hours under the conditions of a temperature of 60.degree. C and 90%RH is 85% or more of the initial value thereof before storage under these conditions in a binder. The magnetic recording medium is especially suitable for high density recording, having sufficient sensitivity and excellent resistance.

A magnetic recording medium for high density recording comprising a support having thereon a magnetic recording layer comprising a ferromagnetic metal powder of the Fe-Co-Cr-B system and having a coercive force of about 700 to 500 oersteds in the oriented direction of the magnetic substance and a residual magnetic flux density of about 1500 gausses or more, the residual magnetic flux density of which after storage for 160 hours under the conditions of a temperature of 60.degree.C and 90%RH is 85% or more of the initial value thereof before storage under these conditions in a binder. The magnetic recording medium is especially suitable for high density recording, having sufficient sensitivity and excellent resistance.

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Odawara, Japan

Matsuaki Nakamura