Patent ID: 9202502
Filing Date: 2015-12-01
Classification: G11B,H01F

Abstract:
1. A method of manufacturing magnetic particles, which comprises: adding a carboxylic acid compound to a water-based magnetic liquid, wherein the water-based magnetic liquid comprises magnetic particles dispersed in an acidic water-based solvent, and the carboxylic acid compound comprises one or more branched alkyl groups and/or fluorine-containing substituents selected from the group consisting of fluorine atoms and alkyl groups substituted with one or more fluorine atoms and is selected from the group consisting of aromatic compounds and aliphatic compounds having one or more carboxylic acid (salt) groups denoted by: wherein M denotes a hydrogen atom or an alkali metal atom, provided that when the number of the carboxylic acid (salt) groups contained within the molecule thereof is 1, the number of carbon atoms, excluding the carboxylic acid (salt) group portion, is equal to or more than 1 but equal to or less than 13; and then collecting the magnetic particles from the water-based magnetic liquid to obtain the magnetic particles the surfaces of which have been modified by being coated with the carboxylic acid compound.