Abstract: The present invention provides a magnetic recording medium wherein both of a reduction in the particle diameter of a ferromagnetic powder and an increase in the filling ratio of the powder in a magnetic layer are attained and the magnetic layer is excellent in surface smoothness and electromagnetic conversion property.

Abstract: The present invention provides a magnetic recording medium wherein a fine non-magnetic inorganic powder, the dispersibility of which is improved, is used to improve the surface smoothness of a lower non-magnetic layer, thereby giving an excellent surface smoothness of an upper magnetic layer and electromagnetic conversion property; and a production process thereof. A magnetic recording medium comprising at least a non-magnetic support, a lower non-magnetic layer on one surface of the non-magnetic support, and an upper magnetic layer on the lower non-magnetic layer, wherein the upper magnetic layer contains at least a ferromagnetic powder, and a binder resin material, and the lower non-magnetic layer contains at least carbon black, iron oxide, and a binder resin material, and the iron oxide has an average major axis length of 30 to 100 nm, and a specific surface area based on the BET method of 80 to 120 m2/g, and the iron oxide contains moisture in an amount per unit specific surface area of 0.13 to 0.

Abstract: The present invention provides a magnetic recording medium which has a thin film magnetic layer considerably excellent in surface smoothness, and is excellent in electromagnetic conversion property. A magnetic recording medium comprising a non-magnetic support, a lower non-magnetic layer comprising at least a non-magnetic powder and a binder resin on one surface of the non-magnetic support, and a magnetic layer comprising at least a ferromagnetic powder and a binder resin on the lower non-magnetic layer, wherein when the magnetic recording medium is subjected to extraction treatment with water, 7 to 23 ?g of PO43? ions are extracted per 10 mm3 of the volume of the lower non-magnetic layer of the magnetic recording medium.

Abstract: A method for manufacturing magnetic paint or non-magnetic paint, which can produce a magnetic recording medium having excellent surface smoothness by appropriately setting the condition of a dispersion process for improving the dispersibility of the paint, and a magnetic recording medium are provided. The magnetic paint or the non-magnetic paint is produced by performing a dispersion process of a mixed solution, in which a magnetic powder or a non-magnetic powder is mixed into a binder solution containing a binder and a solvent, with a medium dispersion device. The method includes the steps of adjusting the viscosity of the mixed solution to 1,500 cP or less on a BL type viscometer at 20 rpm basis, and performing a dispersion process with the medium dispersion device using dispersion media having an average particle diameter of 0.5 mm or less at a dispersion circumferential speed of 8 to 15 m/s.

Abstract: A method for manufacturing magnetic paint or non-magnetic paint, which can produce a magnetic recording medium having excellent surface smoothness by appropriately setting the condition of a dispersion process for improving the dispersibility of the paint, and a magnetic recording medium are provided. The magnetic paint or the non-magnetic paint is produced by performing a dispersion process of a mixed solution, in which a magnetic powder or a non-magnetic powder is mixed into a binder solution containing a binder and a solvent, with a medium dispersion device. The method includes the steps of adjusting the viscosity of the mixed solution to 1,500 cP or less on a BL type viscometer at 20 rpm basis, and performing a dispersion process with the medium dispersion device using dispersion media having an average particle diameter of 0.5 mm or less at a dispersion circumferential speed of 8 to 15 m/s.

Abstract: A method for manufacturing a magnetic recording medium is provided which has high recording density and which is less likely to cause problems of a magnetic tape such as inappropriate contact with a head, unstable running, and damage. A back-coat layer containing plate-like inorganic pigment (plate-like inorganic pigment-containing layer) is formed over a non-magnetic support to produce an intermediate product having the support and the back-coat layer. Then, the intermediate product is subjected to calendering between at least one pair of metal rolls.

Abstract: A method of manufacturing a magnetic recording medium comprising forming a reinforcing layer on a first surface of a non-magnetic support, performing a surface treatment that applies external energy to a surface of the reinforcing layer, and forming a functional layer on the surface of the reinforcing layer that has been subjected to the surface treatment. By doing so, the functional layer can be prevented from peeling off the reinforcing layer with no increase in manufacturing cost or fall in manufacturing yield.

Abstract: A method for manufacturing magnetic paint is provided, wherein a dispersion condition is appropriately controlled to excellently disperse a magnetic powder composed of fine particles adaptable for a higher recording density, so that magnetic paint having excellent dispersibility can be prepared, and a magnetic recording medium having excellent surface roughness is provided. The magnetic paint is prepared by the step of subjecting a mixed solution containing at least a binder, a solvent, and a magnetic powder to a dispersion treatment with a dispersion device by the use of dispersion media through at least dispersion step, wherein the dispersion in the main dispersion step is carried out by the use of dispersion media having an average particle diameter y (mm) satisfying the relationship, which is represented by formula y?0.01x, with the average maximum diameter x (nm) of the magnetic powder.

Abstract: A magnetic recording medium has at least a non-magnetic layer and a magnetic layer formed in that order on one surface of a non-magnetic support. The non-magnetic layer is formed using a non-magnetic coating composition including a (meth)acryloyl group in a range of 11 mmol to 30 mmol, inclusive relative to 100 parts by weight of non-magnetic powder.

Abstract: A radiation curing polyurethane resin for a magnetic recording medium which is capable of realizing a lower non-magnetic layer that can secure sufficient coating film strength with a lower radiation dose. A polyurethane resin which contains active hydrogen, and a sulfur-containing polar group in an amount of not less than 0.05 mmol/g to not more than 0.10 mmol/g, inclusive, but does not contain a basic polar group in its molecule and is formed only by an aliphatic segment, is modified on the active hydrogen into a radiation curing polyurethane resin by a compound having an acrylic double bond.

Abstract: A magnetic recording medium which makes it possible to further increase the recording capacity while maintaining a required flexibility thereof. A magnetic tape has a lower non-magnetic layer and a magnetic layer formed on one surface of a base film in the mentioned order. The lower non-magnetic layer is formed of a non-magnetic coating material containing a non-magnetic powder, an electron beam curing binder, a dispersant having an amine group, and a thermosetting agent.

Abstract: A method for manufacturing magnetic paint or non-magnetic paint, which can produce a magnetic recording medium having excellent surface smoothness by appropriately setting the condition of a dispersion process for improving the dispersibility of the paint, and a magnetic recording medium are provided. The magnetic paint or the non-magnetic paint is produced by performing a dispersion process of a mixed solution, in which a magnetic powder or a non-magnetic powder is mixed into a binder solution containing a binder and a solvent, with a medium dispersion device. The method includes the steps of adjusting the viscosity of the mixed solution to 1,500 cP or less on a BL type viscometer at 20 rpm basis, and performing a dispersion process with the medium dispersion device using dispersion media having an average particle diameter of 0.5 mm or less at a dispersion circumferential speed of 8 to 15 m/s.

Abstract: The present invention provides a magnetic recording medium which has a thin film magnetic layer considerably excellent in surface smoothness, and is excellent in electromagnetic conversion property. A magnetic recording medium comprising a non-magnetic support, a lower non-magnetic layer comprising at least a non-magnetic powder and a binder resin on one surface of the non-magnetic support, and a magnetic layer comprising at least a ferromagnetic powder and a binder resin on the lower non-magnetic layer, wherein when the magnetic recording medium is subjected to extraction treatment with water, 7 to 23 ?g of PO43? ions are extracted per 10 mm3 of the volume of the lower non-magnetic layer of the magnetic recording medium.

Abstract: A magnetic recording medium comprises a back coat layer containing carbon black and alumina as non-magnetic powder. The relationship between the abrasivity (y) in microns of the back coat layer and the alumina content (x) parts by weight to 100 parts by weight of non-magnetic powder excluding alumina satisfies four equations y?4.6x+12.2, y?4.1x+10.8, y?13, y?17. The abrasivity is measured such that an edge of a prismatic Sendust bar is pushed perpendiculary onto the back coat layer such that the magnetic recording medium is pressed at an approaching angle of 12 degree, and the magnetic recording medium is supported by a tension of 0.526 N/cm per unit width and a 50-m length thereof is moved back and forth one time over the Sendust bar at a running speed of 0.3 m/s.

Abstract: The present invention provides a magnetic recording medium having high durability and reliability compatible with MR heads by satisfactorily controlling the grinding ability irrespective of materials, dispersion methods, application methods and other manufacturing methods.

Abstract: A method for manufacturing magnetic paint is provided, wherein a dispersion condition is appropriately controlled to excellently disperse a magnetic powder composed of fine particles adaptable for a higher recording density, so that magnetic paint having excellent dispersibility can be prepared, and a magnetic recording medium having excellent surface roughness is provided. The magnetic paint is prepared by the step of subjecting a mixed solution containing at least a binder, a solvent, and a magnetic powder to a dispersion treatment with a dispersion device by the use of dispersion media through at least dispersion step, wherein the dispersion in the main dispersion step is carried out by the use of dispersion media having an average particle diameter y (mm) satisfying the relationship, which is represented by formula y≦0.01x, with the average maximum diameter x (nm) of the magnetic powder.

Abstract: A magnetic recording medium comprises a back coat layer containing carbon black and alumina as nonmagnetic powder. The relationship between the abrasivity (y) in microns of the back coat layer and the alumina content (x) parts by weight to 100 parts by weight of non-magnetic powder excluding alumina satisfies four equations y≦4.6x+12.2, y≧4.1x+10.8, y≧13, y≦17. The abrasivity is measured such that an edge of a prismatic Sendust bar is pushed perpendiculary onto the back coat layer such that the magnetic recording medium_is pressed at an approaching angle of 12 degree, and the magnetic recording medium is supported by a tension of 0.526 N/cm per unit width and a 50-m length thereof is moved back and forth one time over the Sendust bar at a running speed of 0.3 m/s.

Abstract: A method for manufacturing magnetic paint or non-magnetic paint, which can produce a magnetic recording medium having excellent surface smoothness by appropriately setting the condition of a dispersion process for improving the dispersibility of the paint, and a magnetic recording medium are provided. The magnetic paint or the non-magnetic paint is produced by performing a dispersion process of a mixed solution, in which a magnetic powder or a non-magnetic powder is mixed into a binder solution containing a binder and a solvent, with a medium dispersion device. The method includes the steps of adjusting the viscosity of the mixed solution to 1,500 cP or less on a BL type viscometer at 20 rpm basis, and performing a dispersion process with the medium dispersion device using dispersion media having an average particle diameter of 0.5 mm or less at a dispersion circumferential speed of 8 to 15 m/s.

Abstract: The invention provides a magnetic recording medium which is reduced in the occurrence of a dropout and has excellent durability. The magnetic recording medium comprises a magnetic layer on one surface of a non-magnetic support and a back-coat layer, containing mainly a non-magnetic powder and a binder, on the other surface. The back-coat layer includes (a) a carbon black having an average particle size of 15 to 25 nm, (b) a carbon black having an average particle size of 60 to 80 nm and (c) CaCO3 and/or BaSO4 having an average particle size of 30 to 75 nm as the non-magnetic powder. The back-coat layer preferably includes said carbon black (a), said carbon black (b) and said CaCO3 and/or BaSO4 (c) in a ratio of (a)/(b)/(c)=60-80/3-15/15-30 by weight.

Abstract: An apparatus for manufacturing a welded pipe. The apparatus includes a cage or cluster roller molding system. In either case, a rotary axis of each roller is slanted counterclockwise or clockwise with respect to a manufacturing line direction of the apparatus. The adjustable positioning of the rotary axis reduces vertical slip caused when the strip of material passes along the contact surface of the roller.