Fuji Photo Film Company, Limited

Takao Ohya

Yasuo Nishikawa

Kiyomi Ejiri

Satoru Hayakawa

Hiroshi Hashimoto

Tsutomu Okita

Akihiro Matsufuji

Jun Nakagawa

Mikihiko Kato

Akira Kasuga

Toshio Kawamata

Fusao Yamanaka

Hiroaki Araki

Hajime Miyatsuka

A magnetic recording medium comprising a non magnetic support having thereon a magnetic layer comprising binder resins, ferromagnetic particles and an organic phosporus compound.

Magnetic recording medium comprising ferromagnetic particles, binder

A magnetic recording medium having an improved running durability is disclosed, which comprises a non-magnetic support having formed thereon a magnetic layer mainly composed of a ferromagnetic powder and a binder resin, wherein an ester compound selected from the group consisting of a phthalic acid diester represented by formula (I) and a benzenetricarboxylic acid triester represented by formula (II) is contained in the magnetic layer or coated on the magnetic layer: ##STR1## wherein R.sup.1 and R.sup.2, which may be the same or different, each represents a straight chain or branched alkyl or alkenyl group and the sum of the carbon atoms of R.sup.1 and R.sup.2 is at least 22; and ##STR2## wherein R.sup.3, R.sup.4 and R.sup.5, which may be the same or different, each represents a straight chain or branched alkyl or alkenyl group and the sum of the carbon atoms of R.sup.3, R.sup.4 and R.sup.5 is at least 22, said ester compound being contained in the magnetic layer in an amount of from 1 to 25% by weight based on the amount of the ferromagnetic power in the magnetic layer or being coated on the magnetic layer in an amount of from 2 to 50 mg/m.sup.2.

Magnetic recording medium lubricant comprising a phthalic acid diester

A magnetic recording medium is disclosed, which has a magnetic layer on a non-magnetic support, wherein at least a mixture of ester compounds shown by formula (I) obtained by the reaction of a straight chain or branched fatty acid having from 12 to 30 carbon atoms and branched alcohols having from 10 to 32 carbon atoms synthesized by oxo synthesis is retained in or on the magnetic layer: ##STR1## wherein R.sub.1 represents a straight chain or branched alkyl group having from 11 to 29 carbon atoms or a straight chain or branched alkenyl group having from 11 to 29 carbon atoms, and R.sub.2 represents a branched alkyl group having from 10 to 32 carbon atoms. The magnetic recording medium has an excellent running durability in wide ranges of temperature and humidity condition.

Magnetic recording medium lubricated by a mixture of methyl branched iso

A magnetic recording medium is disclosed, which comprises a non-magnetic support having provided thereon a magnetic layer mainly composed of a ferromagnetic powder and a binder resin comprising (i) a polymer having at least one polar group selected from --SO.sub.3 M.sup.1, --OSO.sub.3 M.sup.1, --COOM.sup.1, ##STR1## wherein M.sup.1 represents a hydrogen atom, Li, Na or NR.sub.4 (wherein R represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkanol group), and M.sup.2 represents a hydrogen atom, Li, Na, an alkyl group, or NR.sub.4 (wherein R has the same significance as defined above); or (ii) a compound having at least one polar group selected from --SO.sub.3 M.sup.3, --COOM.sup.3, and --PO.sub.3 (M.sup.3).sub.2 (wherein M.sup.3 represents a hydrogen atom, an alkali metal, or an ammonium group) and containing at least one carbon-carbon unsaturated bond in the molecule, said magnetic layer containing at least one ester compound represented by following formula (I), (II), or (III), and when the binder resin comprises the compound (ii), the magnetic layer is irradiated by radiations: ##STR2## wherein R.sup.1 represents a straight chain or branched alkyl group having from 7 to 29 carbon atoms or a straight chain or branched alkenyl group having from 7 to 29 carbon atoms; l, k, m, and n represents an integer; l and n each is at least 2, and the sum of n and m and the sum of k and l are from 7 to 33.

Magnetic recording medium comprising a polar group containing resin or

A magnetic recording medium is disclosed, comprising a nonmagnetic support having thereon a magnetic layer, wherein at least one of ester compounds represented by formula (I) is present in or on the magnetic layer, ##STR1## wherein R.sub.1 represents a straight chain, saturated alkyl group having 6 to 12 carbon atoms, R.sub.2 represents a straight chain, saturated alkyl group having 4 to 10 carbon atoms, and R represents a branched or straight chain alkyl group having 4 to 22 carbon atoms.

Magnetic recording medium containing an ester lubricant branched from

A magnetic recording medium comprising a non-magnetic support having provided thereon a magnetic layer comprising a ferromagnetic powder dispersed in a binder,

Magnetic recording medium using a binder resin containing a polar group,

A magnetic recording medium comprises a nonmagnetic support and a magnetic recording layer containing a ferromagnetic powder which is provided on the support. The magnetic recording layer contains a binder resin having a acid residue or a salt thereof and a fatty acid ester compound having the formula (I): ##STR1## wherein R is a hydrocarbon group having 11-21 carbon atoms, R.sup.1 is hydrogen atom or a hydrocarbon group having 1-3 carbon atoms, and R.sup.2 and R.sup.3 are the same or different and each is a hydrocarbon group having 1-8 carbon atoms. The total number of carbon atoms contained in R.sup.1, R.sup.2 and R.sup.3 being not less than 3 carbon atoms. Alternatively, the fatty acid ester can be coated on the magnetic layer.

Magnetic recording medium using a fatty acid ester lubricant wherein the

A magnetic recording medium comprising a nonmagnetic support and a magnetic recording layer provided on the support, wherein the magnetic recording layer contains a compound having a polar group (i.e., a carboxylic acid group, a carboxylic acid salt group, a sulfonic acid group or a sulfonic acid salt group) which is bonded to an aromatic ring directly or indirectly through a polymethylene group having not more than 4 carbon atoms or an unsaturated straight-chain hydrocarbon group having not more than 4 carbon atoms.

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Kanagawa, Japan

Takao Ohya