Abstract: A coating agent for a base for ink-jet printing comprises an alumina dispersion containing dispersed alumina and aluminium nitrate dissolved in an aqueous dispersing medium, and a binder. This coating agent and the coated base material are free of irritating odor, contain alumina well dispersed therein, and provide printed images on the inkjet-printing materials, which images are excellent in the color density, resistance to water, resistance to light and color definition.

Abstract: This invention provides an alumina dispersant mainly comprised of a nitrogen-containing monocarboxylic acid, an alumina dispersion liquid comprised of alumina particles dispersed well in an aqueous dispersing medium, a treating agent for use in making inkjet-printing materials, comprised of the alumina dispersion, and the inkjet-printing materials prepared by using the treating agent to have a high glossiness, high absorption, high water resistance, high reproducibility and good roundness of dots.

Abstract: The present invention provides a magnetic fluid which comprises a magnetic fluid comprising magnetic fine particles coated with a fatty acid in an oily medium, and at least one selected from the group consisting of sulfonate surfactants and animal waxes, has an excellent stability even when used at a high temperature and high humidity and having the fluidity maintained for a long period, and is suitable for use particularly in a severe environment as a bearing, magnetic damper, magnetic seal, specific gravity separator, liquid damper, switch, acceleration sensor, tilt sensor, or heat exchanger for heat pipe or heat sink, and further a magnetic fluid-stabilizing additive allowing the magnetic fluid to have an excellent stability for a long period while maintaining the magnetic fluid's own performance even when used at a high temperature and high humidity for a long period, and a method of stabilizing the magnetic fluid.