Fuji Photo Film Company, Limited

Other

Hiroaki Araki

Kiyomi Ejiri

Hiroshi Hashimoto

Kazuo Kato

Shinji Saito

Hiroshi Ogawa

Masashi Aonuma

Kenichi Masuyama

Toshihiko Miura

Mikio Ohno

Toshichika Aoki

Tsutomu Okita

Chiaki Mizuno

Naoto Murao

Kenichi Yoden

Yasuyuki Tanaka

Tatsuji Kitamoto

Akihiro Matsufuji

Yasuo Nishikawa

Nobuo Yamazaki

Akira Kasuga

Takeshi Kakuta

Hiroaki Doushita

Akira Ushimaru

Yutaka Kakuishi

Kazutoshi Katayama

Kiyotaka Fukino

Tomohiro Ichikawa

Takao Ohya

Kunihiko Honda

Tsuneo Yoshida

A magnetic recording medium is provided comprising a non-magnetic support and at least one magnetic layer comprising ferromagnetic metal particles principally containing iron, having a spindle shape and having an average major axis length of 0.15 &mgr;m or less, and a binder resin, and optionally further comprising, between the support and the magnetic layer, at least one adhesive layer or at least one non-magnetic layer principally containing a non-magnetic inorganic powder and a binder, and wherein center line average surface roughness Ra of the magnetic layer surface being 2 to 6 nm, said recording medium having the following properties; steel ball wear at 23&deg; C. and 70% RH being 2&times;10 to 4&times;10 mm , surface C/Fe ratio measured by Auger electron spectroscopy being 50 to 100, and coefficient of friction between the magnetic layer surface and an SUS rod having a roughness of 8 to 10 nm being 0.2 to 0.3.

Magnetic recording medium comprising spindle-shaped ferromagnetic metal particles

A magnetic recording medium is formed from a non-magnetic support, and a magnetic layer formed on the support and including mainly a binder resin and a ferromagnetic metal powder including mainly Fe. The magnetic layer includes an abrasive and a lubricant. The abrasive present on the surface of the magnetic layer satisfies the relationship 0.01&lE;H /H &lE;0.3 where H denotes the number of particles per unit area having a height less than 10 nm (particles/&mgr;m ) and H denotes the number of particles per unit area having a height equal to or greater than 15 nm (particles/&mgr;m ). The magnetic recording medium has a surface lubricant index of 3 to 11. The height of the abrasive particles can be controlled by, for example, a blade treatment using an abrasive tape (LTBL system) or a diamond powder-studded rotating roll (DWBL system).

Magnetic recording medium

A 2 reel type data storage magnetic tape cassette ( ) is provided with reels ( ) around which a magnetic recording medium ( ) is wound. The magnetic recording medium ( ) includes a support, a non-magnetic layer comprising a non-magnetic powder and a binder on one surface of the support, a magnetic layer comprising a ferromagnetic metal powder and a binder on top of the non-magnetic layer, and a back layer comprising a carbon black powder and a binder on the other side of the support. The magnetic tape cassette ( ) is further provided with a rotating guide roller ( ) made of a resin within the cassette ( ). The rotating guide roller ( ) has a ten-point average roughness Rz of 3.0 to 4.5 &mgr;m and is in contact with the surface of the magnetic layer having a center plane average roughness SRa of 2.0 to 3.5 nm.

Magnetic tape cassette

A magnetic recording medium having little head staining and favorable dropout and error rates when recording after extended or high-temperature and -humidity storage. The medium has, on a nonmagnetic support, a magnetic layer of coated ferromagnetic metal powder containing Fe and binder. The ferromagnetic metal powder contains at least Al, Co and Y, and, respectively, has ratios of Al to Fe (Al/Fe) ranging from 5 to 15% by atom, Co to Fe (Co/Fe) from 1 to 25% by atom, and Y to Fe (Y/Fe) ranging from 0.5 to 5% by atom. Si and Nd either are absent or are each found in an amount not more than 0.01% by atom with respect to Fe. The magnetic layer contains a fatty acid and a fatty acid ester, the fatty acid ester being a fatty alkyl ester compound having an acid-hydrolytic speed not more than 0.03/hour

The present invention discloses a magnetic recording particulate mediumhaving amagnetic layer on anonmagnetic support, the magnetic layer containing a ferromagnetic metal powder and a binder and having a coercive force of 1,400 to 1,700 Oe, wherein the ferromagnetic metal powder is spindle-shaped particles consisting essentially of Fe and having a Co/Fe ratio of from 1 to 5 atomic %, an Al/Fe ratio of from 5 to 15 atomic %, an average major axis length of 0.1 to 0.2 .mu.m and a specific surface area of 40 to 50 m.sup.2 /g, and the binder contains a polyurethane consisting essentially of a diol component comprising a polyether polyol and a polyester polyol and a polyisocyanate component. This magnetic recording particulate medium is characterized by minimal head wear, freedom from head clogging, and satisfactory electromagnetic characteristics.

Magnetic recording particulate medium

The present invention discloses a magnetic tape for use in a magnetic recording/reproduction system having a relative speed of 15 m/s or more between a tape and a head for recording and reproducing the tape; the magnetic tape having at least one magnetic layer provided on a nonmagnetic support, the magnetic layer comprising an Al-containing ferromagnetic powder and alumina dispersed in a binder, and a backcoat layer provided on the surface of the nonmagnetic support opposite to the magnetic layer, wherein the intensity ratio between Al and Fe (Al/Fe), as measured by ESCA, in the surface of the magnetic layer is 0.15 to 0.25. The use of this magnetic tape enables improved electromagnetic characteristics and durability to be achieved at a high recording density and a high transfer speed.

Magnetic tape

A magnetic recording medium having improved electromagnetic characteristics and running properties is disclosed. The magnetic recording medium comprises a non-magnetic support having thereon a plurality of magnetic layers consisting of two or more layers composed of a first lower magnetic layer and a second upper magnetic layer, provided on said support by either co-coating the lower magnetic layer and the upper magnetic layer in the wet state, or coating the lower magnetic layer and then the upper magnetic layer while the lower magnetic layer is still in the wet state; wherein the cobalt-modified iron oxide is employed as the ferromagnetic powder contained in the lower magnetic layer, ferromagnetic metal is employed as the ferromagnetic powder contained in the upper magnetic layer, both the ferromagnetic powder contained in the lower magnetic layer and the ferromagnetic powder contained in the upper magnetic layer having an average major axis length of 0.25 .mu.m or less and an average acicular ratio of 10 or less, a difference in the average major axis length between the ferromagnetic powder contained in the lower magnetic layer and that contained in the upper magnetic layer of 0.08 .mu.m or less, and a difference in the average acicular ratio between the ferromagnetic powder contained in the lower layer and that contained in the upper layer of 4 or less.

A magnetic recording medium having two or more magnetic layers is disclosed, comprising a first magnetic layer and a second magnetic layer which-have been provided in this order on a surface of a nonmagnetic support, and which contain ferromagnetic particles and a binder, wherein said second magnetic layer (outermost layer) contains nonmagnetic particles having a pH of less than 7, and a Mohs' hardness of 6 or more, in an amount of from 1 to 20 parts by weight, per 100 parts by weight of the ferromagnetic particles in the second magnetic layer, and said first magnetic layer contains nonmagnetic particles having a pH of 7 or more, and a Mohs' hardness of 6 or more, in an amount of from 5 to 50 parts by weight, per 100 parts by weight of the ferromagnetic particles in the first magnetic layer.

A magnetic recording medium is disclosed, comprising a non-magnetic support with an undercoating layer having formed thereon one or more magnetic layers. The undercoating layer contains a polyester resin or polyurethane resin having at least one polar group selected from the group consisting of --SO.sub.3 M, --OSO.sub.3 M, --COOM, and --OPO.sub.3 M.sub.2 (wherein M represents a hydrogen atom, an alkali metal, or an ammonium base, and M in different polar group or plural M's within the same polar group may be the same or different), and a glass transition temperature (Tg) of from 40.degree. C. to 80.degree. C. The magnetic layer contains a binder resin having at least one polar group selected from the same group as defined above. The recording medium has excellent adhesion between the non-magnetic support and the magnetic layer, high running durability and excellent electromagnetic characteristics.

A magnetic recording medium improved in electromagnetic characteristics, running durability and running properties is disclosed, comprising a non-magnetic support and at least one magnetic layer formed thereon, said magnetic layer having a ferromagnetic powder dispersed in a binder, wherein said magnetic layer contains at least one member selected from the group consisting of an aromatic phosphoric acid or a derivative thereof, an aromatic phosphonic acid or a derivative thereof, and an aromatic sulfonic acid or a derivative thereof, and wherein said ferromagnetic powder has a pH of at least 7, and said binder is a vinyl chloride copolymer having an epoxy group and a hydroxyl group attached to an alkyl chain group. Also, a method for producing a magnetic recording medium is disclosed which comprises the steps of kneading and dispersing a ferromagnetic powder having a pH of at least 7, at least one member selected from the group consisting of an aromatic phosphoric acid or a derivative thereof, an aromatic phosphonic acid or a derivative thereof, and an aromatic sulfonic acid or a derivative thereof, and a vinyl chloride copolymer having an epoxy group and a hydroxyl group attached to an alkyl chain group, together with a solvent; and then optionally adding at least one additive thereto, and mixing to prepare a magnetic coating; and then applying the resulting magnetic coating to a non-magnetic support; drying, calendering and then heat treating.

Magnetic recording medium comprising ferromagnetic powder having a pH of

A magnetic recording medium improved in reproduced output over a wide wavelength region, and methods for producing the same are disclosed, the magnetic recording medium having at least two magnetic layers each containing ferromagnetic powders dispersed in binders, which medium comprises a lower magnetic layer containing an acicular ferromagnetic powder having a coercive force of 600 to 2,000 Oe and an upper magnetic layer containing a plate-shaped ferromagnetic alloy powder having a coercive force of 1,000 to 5,000 Oe, a saturation magnetization of 90 to 150 emu/g and an axis easily magnetizable vertically to a plate surface.

Magnetic recording medium and method for producing the same

A magnetic recording medium excellent in electromagnetic conversion characteristics and running characteristics is disclosed, which comprises a non-magnetic support and a magnetic layer formed thereon, said magnetic layer containing ferromagnetic particles dispersed in a binder, wherein said magnetic layer comprises a number of pores, said pores having

A magnetic recording medium comprising a nonmagnetic support having formed thereon a magnetic layer containing ferromagnetic particles dispersed in a binder, wherein the surface of the magnetic layer has pores of (a) at most 50 .ANG. in the average value of pore inlet diameters measured by a nitrogen gas adsorption method and (b) at least 25 .ANG. in the half value width of the frequency distribution curve of the pore inlet diameters.

Magnetic recording medium having a surface with pores of specified

A magnetic recording medium comprising a non-magnetic support having provided thereon a magnetic layer containing ferromagnetic alloy particles, fine particles of metal oxides and carbon black dispersed in a binder. The ferromagnetic alloy particles have a pH of from 4.5 to 7.5. The carbon black has a pH in a range of from 6.5 to 10.5. At least one kind of fine particles of metal oxides have Mohs' hardness of 5 or higher and pH of at least 3.5 but less than 7.5 and at least one kind of fine particles of metal oxides have Mohs' hardness of 5 or higher and a pH of from 7.5 to 10.5. The binder contains a polymer having at least one kind of an acidic polar group selected from the group consisting of a phosphate group, a phosphoric acid group, a sulfonic acid group, a carboxylic acid group, a metal salt of phosphoric acid group, a metal salt of sulfonic acid group, and a metal salt of carboxylic acid group.

A magnetic recording medium is described, comprising a nonmagnetic support having thereon a magnetic layer containing a binder which is cross-linkable or polymerizable by radiation irradiation and ferromagnetic particles, the ferromagnetic particles being metal or metal alloy particles mainly comprising iron having a crystal size of 300 .ANG. or less, having an atomic ratio of oxygen atoms to iron atoms of from 1.6 to 3.0 on the surface of the particles, and the magnetic layer having been irradiated with radiation, and comprising a nonmagnetic support having thereon a magnetic layer containing a binder comprising thermoplastic resins, thermosetting resins, reactive type resins and mixtures thereof and ferromagnetic particles, said ferromagnetic particles being metal or metal alloy particles mainly comprising iron having a crystal size of 250 .ANG. or less, and having an atomic ratio of oxygen atoms to iron atoms of from 1.6 to 3.0 on the surface of said particles.

Growing community of inventors

Kanagawa, Japan

Hiroaki Araki