Fujifilm Corporation

Fuji Photo Film Company, Limited

Masahiko Mori

Kiyomi Ejiri

Kazufumi Omura

Hiroshi Hashimoto

Yuichiro Murayama

Katsumi Araki

Koji Naoe

Masataka Yoshizawa

Takeshi Harasawa

Hiroyuki Suzuki

Katsuhiko Meguro

Yoshihiro Sawayashiki

The magnetic recording medium has a magnetic layer containing multiple nonmagnetic particles having a ratio, major axis length/minor axis length, of less than or equal to 1.5, the multiple nonmagnetic particles are present in the magnetic layer in a state where, when the depth to which each of the multiple nonmagnetic particles is embedded in the magnetic layer in observation of a sectional image picked up by SEM is denoted as b and the thickness of the magnetic layer as t, the average value of the ratio of b/t is less than or equal to 0.9, and the number of protrusions 5 nm or greater in height is 800 or greater and the number of protrusions 20 nm or greater in height is 20 or less as measured by AFM per an area 40 &#x3bc;m&#xd7;40 &#x3bc;m on the magnetic layer side surface of the magnetic recording medium.

Magnetic recording medium, magnetic signal reproduction device and method of manufacturing magnetic recording medium

The magnetic recording medium includes: a non-magnetic support; and a non-magnetic layer including a non-magnetic powder and a magnetic layer including a ferromagnetic powder on the non-magnetic support in this order, in which a vertical squareness ratio is 0.70 to 1.00, a center line average roughness Ra measured regarding a surface of the magnetic layer with an atomic force microscope is equal to or smaller than 2.5 nm, and an interface variation rate between the magnetic layer and the non-magnetic layer in a cross section image obtained by imaging with a scanning electron microscope is equal to or less than 2.5%.

Magnetic recording medium having non-magnetic layer and characterized vertical squareness ratio, and magnetic recording and reproducing device

The magnetic recording medium includes a non-magnetic support; a non-magnetic layer including a non-magnetic powder and a binding agent on the non-magnetic support; and a magnetic layer including a ferromagnetic powder, a binding agent, and a non-magnetic powder on the non-magnetic layer, in which a skewness Rsk obtained using an atomic force microscope in a measurement region of a surface of the magnetic layer having a size of 5 &#x3bc;m&#xd7;5 &#x3bc;m is greater than 0, a maximum peak height Rmax is equal to or smaller than 30.0 nm, and the number of projections having a height equal to or greater than 10 nm is equal to or greater than 10, and a magnetic recording and reproducing device including: this magnetic recording medium; and a magnetic head.

Magnetic recording medium having specific surface characteristics and magnetic recording and reproducing device

The magnetic tape has a nonmagnetic layer, a magnetic layer, and a backcoat layer; with one or both of the magnetic layer and nonmagnetic layer comprising at least one type of lubricant; with the backcoat layer comprising at least one type of lubricant; with a surface lubricant index as measured on a surface of the magnetic layer ranging from 1.00 to 4.00; and

Magnetic tape and magnetic signal reproducing device

An aspect of the present invention relates to a method of manufacturing hexagonal ferrite magnetic powder. The method of manufacturing hexagonal ferrite magnetic powder comprises wet processing hexagonal ferrite magnetic particles obtained following acid treatment in a water-based solvent to prepare an aqueous magnetic liquid satisfying relation (1) relative to an isoelectric point of the hexagonal ferrite magnetic particles: pH0&#x2212;pH*&#x2267;2.5, wherein, pH0 denotes the isoelectric point of the hexagonal ferrite magnetic particles and pH* denotes a pH of the aqueous magnetic liquid, which is a value of equal to or greater than 2.0, adding a surface-modifying agent comprising an alkyl group and a functional group that becomes an anionic group in the aqueous magnetic liquid to the aqueous magnetic liquid to subject the hexagonal ferrite magnetic particles to a surface-modifying treatment, and removing the water-based solvent following the surface-modifying treatment to obtain hexagonal ferrite magnetic particles.

Method of manufacturing magnetic recording medium

An aspect of the present invention relates to a method of manufacturing magnetic powder, which comprises adding an alkali metal salt compound comprising a substituent selected from the group consisting of an alkali metal salt of a carboxyl group and an alkali metal salt of a hydroxyl group to a water-based magnetic liquid comprising magnetic particles dispersed in an acidic water-based solvent to cause the magnetic particles to aggregate in the water-based magnetic liquid; and collecting the aggregated magnetic particles to obtain the magnetic powder.

Magnetic powder and method of manufacturing the same

An aspect of the present invention relates to a method of manufacturing magnetic particles, which comprises adding a carboxylic acid compound to a water-based magnetic liquid, wherein the water-based magnetic liquid comprises magnetic particles dispersed in an acidic water-based solvent, and the carboxylic acid compound is selected from the group consisting of aromatic compounds and aliphatic compounds having one or more carboxylic acid (salt) groups denoted by:&#x2014;COOMwherein M denotes a hydrogen atom or an alkali metal atom, when the number of the carboxylic acid (salt) group contained within the molecule thereof is 1, the number of carbon atoms, excluding the carboxylic acid (salt) group portion, ranges from 1 to 13; and then collecting the magnetic particles from the water-based magnetic liquid to obtain the magnetic particles the surfaces of which have been modified by being coated with the carboxylic acid compound.

Magnetic particles and method of manufacturing the same, and usage thereof

An aspect of the present invention relates to a method of manufacturing hexagonal ferrite magnetic powder, which comprises preparing a melt by melting a starting material mixture comprising a hexagonal ferrite-forming component and a glass-forming component and rapidly cooling the melt to obtain a solidified product, heating the solidified product to precipitate hexagonal ferrite magnetic particles and glass components in the solidified product, subjecting the solidified product to an acid treatment following the heating to remove the glass components by dissolution, incorporating the hexagonal ferrite magnetic particles obtained following the acid treatment into an acidic aqueous solution, followed by separating the particles dispersed in the aqueous solution and the precipitated particles, and subjecting the precipitated particles to a cleaning treatment and then collecting the particles.

Method of manufacturing hexagonal ferrite magnetic powder and its usage

Method of manufacturing magnetic powder

Method of manufacturing hexagonal ferrite magnetic powder, magnetic recording medium and method of manufacturing the same

An aspect of the present invention relates to a magnetic tape comprising a magnetic layer containing a ferromagnetic powder and a binder on a nonmagnetic support, wherein

Magnetic tape and method of manufacturing the same, and magnetic recording device

An aspect of the present invention relates to a magnetic recording medium comprising a magnetic layer comprising a ferromagnetic powder and a binder on a nonmagnetic support, wherein the magnetic layer comprises a compound denoted by general formula (1): wherein, in general formula (1), X denotes a divalent linking group, each of Rand Rindependently denotes an alkyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an alkoxyalkyl group having 2 to 20 carbon atoms, or an aryloxyalkyl group having 7 to 20 carbon atoms, and M denotes a hydrogen atom or a cation.

Magnetic recording medium, method of modifying surface of magnetic powder and magnetic coating material

A compound represented by the Formula (1) below is provided: wherein X denotes a divalent linking group, Rand Rindependently denote an alkyl group having 3 or more carbons and having at least one hydroxy group or an aralkyl group having 8 or more carbons and having at least one hydroxy group, the alkyl group and aralkyl group may have a substituent, and M denotes a hydrogen atom or a cation. There is also provided a polyurethane resin obtained by polymerization of a polyisocyanate and a polyol that includes the compound. There is also provided a magnetic recording medium that includes a non-magnetic support and, above the support, at least one magnetic layer including a ferromagnetic powder dispersed in a binder that includes the polyurethane resin. There is also provided a magnetic recording medium that includes a non-magnetic support, above the support at least one non-magnetic layer including a non-magnetic powder dispersed in a binder (), and, above the non-magnetic layer, at least one magnetic layer having a ferromagnetic powder dispersed in a binder (), in which binder () and/or binder () is the polyurethane resin.

Growing community of inventors

Minami-ashigara, Japan

Masahiko Mori