Abstract: Provided are a manufacturing method of a dispersion including a step A of preparing a mixture containing an edible pigment, an edible dispersant, and water, a step B of applying a hydrostatic pressure equal to or higher than 30 MPa to the mixture, and a step C of performing a dispersion treatment on the mixture to which the hydrostatic pressure is applied; a pigment dispersion for ink jet recording and a manufacturing method thereof; and an ink composition for an ink jet and a manufacturing method thereof.

Abstract: Provided are an iron oxide dispersion for ink jet recording, a method of manufacturing the same, and an ink jet recording method. The iron oxide dispersion for ink jet recording includes: iron oxide particles; a resin that has at least one of an amino group or a quaternary ammonium group and coats at least a part of surfaces of the iron oxide particles; and water, in which an average particle diameter of the iron oxide particles having surfaces at least a part of which are coated with the resin is 90 nm to 400 nm.

Abstract: Provided are a manufacturing method of a dispersion including a step A of preparing a mixture containing an edible pigment, an edible dispersant, and water, a step B of applying a hydrostatic pressure equal to or higher than 30 MPa to the mixture, and a step C of performing a dispersion treatment on the mixture to which the hydrostatic pressure is applied; a pigment dispersion for ink jet recording and a manufacturing method thereof; and an ink composition for an ink jet and a manufacturing method thereof.

Abstract: Provided are an iron oxide dispersion for ink jet recording, a method of manufacturing the same, and an ink jet recording method. The iron oxide dispersion for ink jet recording includes: iron oxide particles; a resin that has at least one of an amino group or a quaternary ammonium group and coats at least a part of surfaces of the iron oxide particles; and water, in which an average particle diameter of the iron oxide particles having surfaces at least a part of which are coated with the resin is 90 nm to 400 nm.

Abstract: A magnetic recording medium, which comprises: a nonmagnetic support; and a magnetic layer comprising a ferromagnetic powder and a binder, wherein an average surface roughness (Ra) at a center of a surface of the magnetic layer measured by using an atomic force microscope (AFM) is 2 nm or less, the maximum height (Rmax) thereof is 50 nm or less, and an arithmetic average of phase difference between a drive signal and a response signal of a probe measured with the atomic force microscope in a tapping mode is from 2 to 20°, and a method of producing the same.

Abstract: The present invention provides a method of manufacturing a magnetic recording medium that is made by applying a magnetic paint containing a ferromagnetic powder and a binder to a nonmagnetic support, wherein the magnetic paint contains a magnetic liquid, which contains the ferromagnetic powder and the binder, and a polishing material liquid, which contains a polishing material and a solvent, and wherein the magnetic liquid and the polishing material liquid are individually subjected to dispersion treatment, the magnetic liquid and the polishing material liquid are then mixed together, and after that, a mixed liquid of the magnetic liquid and the polishing material liquid are subjected to dispersion treatment by application of ultrasonic waves.

Abstract: A magnetic recording medium, which comprises: a nonmagnetic support; and a magnetic layer comprising a ferromagnetic powder and a binder, wherein an average surface roughness (Ra) at a center of a surface of the magnetic layer measured by using an atomic force microscope (AFM) is 2 nm or less, the maximum height (Rmax) thereof is 50 nm or less, and an arithmetic average of phase difference between a drive signal and a response signal of a probe measured with the atomic force microscope in a tapping mode is from 2 to 20°, and a method of producing the same.

Abstract: In the method for producing a magnetic recording medium having a nonmagnetic substrate coated with a magnetic coating material containing a ferromagnetic powder and a binder, the magnetic coating material contains a liquid A constituted by the ferromagnetic powder and a solvent, and a solution B of the binder, and the liquid A and the solution B are mixed together by applying an ultrasonic wave thereto, and are thereafter subjected to dispersion processing. Thereby, coagulated particles of the ferromagnetic powder can be dispersed and the coagulation of the ferromagnetic powder can be prevented, thus making it possible to obtain a liquid of ferromagnetic powder with uniform adsorption of the binder. As a result, a magnetic coating material suitable for a low-noise high-density coating-type magnetic recording medium is obtained.

Abstract: A magnetic recording medium, which comprises: a nonmagnetic support; and a magnetic layer comprising a ferromagnetic powder and a binder, wherein an average surface roughness (Ra) at a center of a surface of the magnetic layer measured by using an atomic force microscope (AFM) is 2 nm or less, the maximum height (Rmax) thereof is 50 nm or less, and an arithmetic average of phase difference between a drive signal and a response signal of a probe measured with the atomic force microscope in a tapping mode is from 2 to 20°, and a method of producing the same.

Abstract: In the method for producing a magnetic recording medium having a nonmagnetic substrate coated with a magnetic coating material containing a ferromagnetic powder and a binder, the magnetic coating material contains a liquid A constituted by the ferromagnetic powder and a solvent, and a solution B of the binder, and the liquid A and the solution B are mixed together by a thin-layer revolving-type fast stirring apparatus, and are thereafter subjected to dispersion processing. Thereby, coagulated particles of the ferromagnetic powder can be dispersed and the coagulation of the ferromagnetic powder can be prevented, thus making it possible to obtain a liquid of ferromagnetic powder with uniform adsorption of the binder. As a result, a magnetic coating material suitable for a low-noise high-density coating-type magnetic recording medium is obtained.

Abstract: The method is for manufacturing the magnetic recording medium in which a magnetic coating containing a ferromagnetic powder and a binder is applied on a nonmagnetic support. The magnetic coating includes: a magnetic liquid containing a ferromagnetic powder and a binder, and an abrasive liquid containing an abrasive and a solvent. The abrasive liquid may further contain the binder. The magnetic liquid and the abrasive liquid are each separately subjected to dispersion treatment, then the abrasive liquid is filtered, and then the magnetic liquid and the abrasive liquid are mixed. The obtained magnetic recording medium has a smooth magnetic layer surface, good electromagnetic conversion properties and excellent running durability and shows little wear of a head.

Abstract: An ultrasonic dispersion device of a batch type comprising an ultrasonic oscillator and a liquid vessel, wherein an oscillation frequency of the ultrasonic oscillator is 20 kHz or less, the ultrasonic oscillator is secured to the liquid vessel, and the ultrasonic oscillator is able to come into contact with a treated liquid.

Abstract: The present invention provides a method of manufacturing a magnetic recording medium that is made by applying a magnetic paint containing a ferromagnetic powder and a binder to a nonmagnetic support, wherein the magnetic paint contains a magnetic liquid, which contains the ferromagnetic powder and the binder, and a polishing material liquid, which contains a polishing material and a solvent, and wherein the magnetic liquid and the polishing material liquid are individually subjected to dispersion treatment, the magnetic liquid and the polishing material liquid are then mixed together, and after that, a mixed liquid of the magnetic liquid and the polishing material liquid are subjected to dispersion treatment by application of ultrasonic waves.

Abstract: A process for producing a magnetic recording medium is provided, the medium being formed from a non-magnetic flexible support, a non-magnetic layer comprising a non-magnetic powder and a binder, and a magnetic layer comprising a ferromagnetic powder and a binder. The non-magnetic layer is provided on top of the support, the magnetic layer is provided on top of the non-magnetic layer, and the non-magnetic powder includes two or more types of non-magnetic powder, including carbon black and a non-magnetic powder other than carbon black. The process includes a step of separately dispersing a non-magnetic liquid A that includes a binder and a non-magnetic powder other than carbon black, and a non-magnetic liquid B that includes carbon black and a binder, and a step of stirring and mixing the non-magnetic liquid A and the non-magnetic liquid B to prepare a non-magnetic coating solution.

Abstract: The method is for manufacturing the magnetic recording medium in which a magnetic coating containing a ferromagnetic powder and a binder is applied on a nonmagnetic support. The magnetic coating includes: a magnetic liquid containing a ferromagnetic powder and a binder, and an abrasive liquid containing an abrasive and a solvent. The abrasive liquid may further contain the binder. The magnetic liquid and the abrasive liquid are each separately subjected to dispersion treatment, then the abrasive liquid is filtered, and then the magnetic liquid and the abrasive liquid are mixed. The obtained magnetic recording medium has a smooth magnetic layer surface, good electromagnetic conversion properties and excellent running durability and shows little wear of a head.

Abstract: In the method for producing a magnetic recording medium having a nonmagnetic substrate coated with a magnetic coating material containing a ferromagnetic powder and a binder, the magnetic coating material contains a liquid A constituted by the ferromagnetic powder and a solvent, and a solution B of the binder, and the liquid A and the solution B are mixed together by applying an ultrasonic wave thereto, and are thereafter subjected to dispersion processing. Thereby, coagulated particles of the ferromagnetic powder can be dispersed and the coagulation of the ferromagnetic powder can be prevented, thus making it possible to obtain a liquid of ferromagnetic powder with uniform adsorption of the binder. As a result, a magnetic coating material suitable for a low-noise high-density coating-type magnetic recording medium is obtained.

Abstract: A process for producing a magnetic recording medium is provided in which a magnetic layer including a ferromagnetic powder and a binder is provided on a non-magnetic flexible support. In the process, a magnetic liquid containing mainly a ferromagnetic powder and a binder, and an abrasive liquid paste including an abrasive and a binder are prepared separately, and the abrasive liquid paste is subsequently subjected to an ultrasonic dispersion treatment and then mixed with the magnetic liquid to prepare a magnetic coating solution for the magnetic layer.

Abstract: In the method for producing a magnetic recording medium having a nonmagnetic substrate coated with a magnetic coating material containing a ferromagnetic powder and a binder, the magnetic coating material contains a liquid A constituted by the ferromagnetic powder and a solvent, and a solution B of the binder, and the liquid A and the solution B are mixed together by a thin-layer revolving-type fast stirring apparatus, and are thereafter subjected to dispersion processing. Thereby, coagulated particles of the ferromagnetic powder can be dispersed and the coagulation of the ferromagnetic powder can be prevented, thus making it possible to obtain a liquid of ferromagnetic powder with uniform adsorption of the binder. As a result, a magnetic coating material suitable for a low-noise high-density coating-type magnetic recording medium is obtained.

Abstract: A process for producing a magnetic recording medium is provided, the medium being formed from a non-magnetic flexible support, a non-magnetic layer comprising a non-magnetic powder and a binder, and a magnetic layer comprising a ferromagnetic powder and a binder. The non-magnetic layer is provided on top of the support, the magnetic layer is provided on top of the non-magnetic layer, and the non-magnetic powder includes two or more types of non-magnetic powder, including carbon black and a non-magnetic powder other than carbon black. The process includes a step of separately dispersing a non-magnetic liquid A that includes a binder and a non-magnetic powder other than carbon black, and a non-magnetic liquid B that includes carbon black and a binder, and a step of stirring and mixing the non-magnetic liquid A and the non-magnetic liquid B to prepare a non-magnetic coating solution.

Abstract: The present invention aims to provide a magnetic recording medium for digital recording/reproducing systems having a small bit area, i.e. a short recording wavelength and a narrow track width, which is a particulate magnetic recording medium showing good electromagnetic characteristics. A magnetic recording medium comprising a nonmagnetic layer containing a nonmagnetic powder and a binder and a magnetic layer containing a ferromagnetic powder and a binder provided in this order on a nonmagnetic substrate wherein said magnetic layer has an average thickness of 0.01-0.1 &mgr;m and the ratio of the area of magnetic recording defects generated upon magnetic development after recording at the shortest recording wavelength to the total magnetic recording area is 0.2-20%.