Fuji Photo Film Company, Limited

Hiroaki Doushita

Masatoshi Takahashi

Kiyomi Ejiri

Takeshi Kakuta

Kunihiko Sano

Takeshi Harasawa

Tadashi Yasunaga

Masaki Suzuki

Satoshi Matsubaguchi

Hiroyuki Tahara

Noriko Inoue

Takako Ozawa

Hiroaki Takano

Shinji Saito

Hiroo Inaba

Katsumi Ryoke

Hitoshi Noguchi

Nobuo Yamazaki

Toshio Ishida

Katsuhiko Meguro

Masami Sato

Toshiyuki Kitahara

Hiroaki Araki

Yasutoshi Okuzawa

Kazuo Kato

Tadashi Ishiguro

Junichi Nakamikawa

Tetsuji Nishida

The present invention provides an optical information recording medium that includes a substrate including a groove with a track pitch of 200 to 400 nm and a groove depth of 20 to 150 nm and having successively disposed thereon a light reflecting layer, a recording layer containing a dye in which information is recorded by irradiation with a laser beam having a wavelength of no greater than 450 nm, an adhesive layer, and a cover layer with a thickness of 0.01 to 0.5 mm. A surface of the optical information recording medium on a side disposed with the cover layer has a center surface average roughness (SRa) of no greater than 3.0 nm when measured over a large surface area and a center surface average roughness (SRa) of no greater than 3.0 nm when measured over a minute surface area.

Optical information recording medium

A magnetic recording medium comprising a non-magnetic support and a magnetic layer containing a ferromagnetic metal powder and a binder, wherein the ferromagnetic metal powder comprises an oxide layer and a metal portion surrounded by the oxide layer, and the ferromagnetic metal powder has an average long axis length of from 30 nm to 55 nm, a coefficient of variation of long axis length of not more than 25%, a coefficient of variation of axial ratio of not more than 20%, and a coefficient of variation of a thickness of the oxide layer of not more than 15%.

Magnetic recording medium and magnetic recording and reproducing method using the same

A magnetic recording tape comprising: a magnetic layer comprising a ferromagnetic powder and a binder; a nonmagnetic layer; a support; and a back coating layer, in this order, wherein the magnetic layer has a surface lubricant index of from 1.3 to 3.5, the back coating layer comprises titanium oxide, &#x3b1;-iron oxide or a mixture thereof as an inorganic oxide powder and carbon black and further comprises from 10 to 30 parts by weight, based on 100 parts by weight of a total amount of the inorganic oxide powder and the carbon black, of a binder, and the back coating layer has a surface lubricant index of from 1.10 to 3.0.

Magnetic recording tape

A magnetic recording medium comprising: a support; and a magnetic layer comprising ferromagnetic metal powder and a binder, wherein the ferromagnetic metal powder is acicular composite magnetic particle powder having an average long axis length of from 20 to 50 nm, and at least a part of a surface of the particle powder is covered with carbon black.

Magnetic recording medium

A magnetic recording medium containing: a support; and a magnetic layer containing a ferromagnetic powder and a binder, wherein the magnetic layer has 100 or less protrusions per 900 &mgr;m on a surface thereof, the protrusion having a height, as measured by AFM, of 30 nm or more, the magnetic layer has a magnetic switching volume of from 0.1&times;10 to 5&times;10 mL, the magnetic layer has a coercive force of 2,000 Oe (159.2 KA/m) or more, and a surface of the support, the surface being opposed to the magnetic layer, has a PSD in a machine direction, as measured by an interferometric roughness tester with a magnification of 5 times, of from 500 to 4,000 &mgr;m at a space wavelength of 10 &mgr;m, and a reproduction process containing reproducing the magnetic recording medium by an MR head.

Magnetic recording medium and reproduction process using the same

A magnetic recording tape comprising: a magnetic layer comprising a ferromagnetic powder and a binder; a nonmagnetic layer; a support; and a back coating layer, in this order, wherein the magnetic layer comprises, as the binder, a polyurethane resin comprising a dimer diol as a diol component, the back coating layer comprises nonmagnetic inorganic powders and from 1 to 5 parts by weight, based on 100 parts by weight of a total amount of the nonmagnetic inorganic powders, of a lubricant, and a number of protrusions having a height, as measured by an atomic force microscope, of from 30 to 100 nm present on a surface of the back coating layer is from 10 to 1,000 per a 90-&mgr;m square.

Provided is a particulate magnetic recording medium affording great improvement in medium noise in a recording and reproduction system adopting MR heads. The magnetic recording medium comprises a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a hexagonal ferrite powder and a binder in this order on a nonmagnetic support. The number of pits having a depth of &frac13; or more of the minimum recording bit length present on a surface of said magnetic layer is equal to or less than 100/10000 &mgr;m , and the center surface average roughness of said magnetic layer surface SRa is equal to or less than 6.0 nm.

Provided is a magnetic recording medium having improved electromagnetic characteristics, particularly, in which the C/N ratio in the high-density recording region is markedly improved. The magnetic recording medium comprises a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a ferromagnetic hexagonal ferrite powder and a binder in this order on a support. The number of magnetic aggregates present in the magnetic layer that are equal to or higher than 0.5 &mgr;m in size and have a magnetic intensity equal to or greater than 20 times the average value of magnetization turbulence obtained from a magnetic force image measured by a magnetic force microscope is equal to or less than 100/2,000 &mgr;m .

A magnetic tape is disclosed, comprising a non-magnetic support having provided on one face thereof a substantially non-magnetic layer containing a non-magnetic powder and a binder and a magnetic layer containing a ferromagnetic powder and a binder, in this order, and having provided on the other face thereof a back coat layer containing carbon black, wherein 16 projections/mm or less of projections having an area of 30 &mgr;m or more and a height of 40 nm or more exist on a surface of the magnetic layer.

Magnetic tape

Provided is a magnetic recording medium having good electromagnetic characteristics, particularly both improved high-density recording characteristics and good durability, and particularly a C/N ratio that is markedly improved in the high-density recording region. A magnetic recording medium comprising a nonmagnetic lower layer and a magnetic layer provided in this order on a support wherein said magnetic layer comprises a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder and a binder and has a coercive force equal to or higher than 143 kA/m. Said magnetic recording medium is a medium for recording signals having a surface recording density ranging from 0.2 to 2 Gbit/inch ; said support has a thickness equal to or less than 5.5 &mgr;m and a Young's modulus in the MD direction equal to or higher than 11,000 Mpa; and said support has on the reverse surface from said magnetic layer a backcoat layer, said backcoat layer having not fewer than 200 and not more than 1,000 protrusions having a height equal to or higher than 50 nm per 10,000 &mgr;m .

Magnetic recording medium comprising a backcoat layer having specific protrusions

Provided is a particulate magnetic recording medium having good processing properties and being inexpensive to produce, similar to prior recording media, wherein by controlling the magnetic clusters that appear due to recording at short wavelengths and thinning of the magnetic layer, good high-density characteristics are achieved in combination with MR heads. The magnetic recording medium comprising an essentially nonmagnetic lower layer and a magnetic layer comprising a ferromagnetic powder and a binder in this order, wherein the magnetic layer has a thickness ranging from 0.01 to 0.15 &mgr;m and a coercivity equal to or higher than 159 kA/m, ferromagnetic particles contained in the ferromagnetic powder have a size less than &frac12; of the minimum recording wavelength, and an average size of magnetic cluster at DC erase is equal to or higher than 0.5&times;10 nm and less than 5.5&times;10 nm .

A magnetic recording tape is described, which comprises a plastic support having provided thereon a magnetic layer comprising a ferromagnetic metal powder dispersed in a binder, wherein the magnetic layer has the product P of the coercivity Hc (Oe) in the in-plane machine direction of the tape and the magnetic flux &phgr;m (G&middot;cm) of from 100 to 160.

Magnetic recording tape with controlled Hc and magnetic flux/unit area value and controlled Cl/Fe intensity

A magnetic recording medium is described, which comprises a support having thereon a substantially nonmagnetic lower layer and a magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder dispersed in a binder provided on the lower layer, which is a magnetic recording medium for recording signals of from 0.17 to 2 G bit/inch,of areal recording density, wherein the magnetic layer has the central plane average surface roughness (Ra) of the measuring range of 121 &mgr;m&times;92 &mgr;m of 5.0 nm or less and that of the measuring range of 1.2 mm&times;0.9 mm of from 8.5 to 21.5 nm measured using an optical interference type surface roughness meter.

A magnetic recording medium which comprises a support having thereon a substantially nonmagnetic lower layer and a magnetic layer comprising a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder dispersed in a binder provided on the lower layer, which is a magnetic recording medium for recording signals of from 0.17 to 2 G bit/inch,of areal recording density, wherein the coercive force of the magnetic layer is 1,800 Oe or more, and the thickness unevenness of the support is 5% or less of the thickness of the support.

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.

Growing community of inventors

Kanagawa, Japan

Hiroaki Doushita