Abstract: The magnetic recording medium comprises a magnetic layer comprising a ferromagnetic powder and a binder on a nonmagnetic support. In the magnetic recording medium, a number of protrusions equal to or greater than 10 nm in height on the magnetic layer surface, as measured by an atomic force microscope, ranges from 50 to 500/1,600 ?m2, the binder comprises a polyurethane resin with a weight average molecular weight ranging from 100,000 to 200,000, and the magnetic layer further comprises a carbonic ester having a molecular weight ranging from 360 to 460.

Abstract: 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 (SRa1) of no greater than 3.0 nm when measured over a large surface area and a center surface average roughness (SRa2) of no greater than 3.0 nm when measured over a minute surface area.

Abstract: 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%.

Abstract: A magnetic tape cartridge wherein a reel with magnetic tape wound thereon is rotatably housed within a cartridge case, the thickness of the magnetic tape being 7 ?m or less and a reel hub constituting the reel being formed from a highly rigid material having a flexural rigidity of 5000 MPa or more.

Abstract: A magnetic recording medium comprising: a non-magnetic support; and a coating layer including a magnetic layer which contains a ferromagnetic powder containing a rare earth element and a binder and optionally a non-magnetic layer which contains a non-magnetic inorganic powder and a binder, wherein an amount of a liberated rare earth element in the coating layer is not more than 30 ppm.

Abstract: A leader tape, which is bonded to a top end of a magnetic tape and is let out toward a magnetic recording and reproduction device while leading the magnetic tape, having a coating layer that contains a powder and a binder on at least one face of a support, which is characterized in that a center line average roughness (Ra) of at least one face of the leader tape is from 10 to 60 nm, and a ratio of a stiffness of the leader tape in a machine direction to that of the magnetic tape in the machine direction is from 6.0 to 400.

Abstract: 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, ?-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.

Abstract: 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.

Abstract: 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;m2 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 0.1×10−17 to 5×10−17 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;m3 at a space wavelength of 10 &mgr;m, and a reproduction process containing reproducing the magnetic recording medium by an MR head.

Abstract: 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.

Abstract: 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 ⅓ 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;m2, and the center surface average roughness of said magnetic layer surface SRa is equal to or less than 6.0 nm.

Abstract: 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 ⅓ 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;m2, and the center surface average roughness of said magnetic layer surface SRa is equal to or less than 6.0 nm.

Abstract: 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;m2.

Abstract: 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/mm2 or less of projections having an area of 30 &mgr;m2 or more and a height of 40 nm or more exist on a surface of the magnetic layer.

Abstract: 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.

Abstract: 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, &agr;-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.

Abstract: 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.

Abstract: 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;m2 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 0.1×10−17 to 5×10−17 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;m3 at a space wavelength of 10 &mgr;m, and a reproduction process containing reproducing the magnetic recording medium by an MR head.

Abstract: 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/inch2; said support has a thickness equal to or less than 5.

Abstract: 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 ½ of the minimum recording wavelength, and an average size of magnetic cluster at DC erase is equal to or higher than 0.5×104 nm2 and less than 5.5×104 nm2.