| 摘要 |
<p>The invention relates to a method of manufacturing an improved pigment of FeOOH particles. The starting material is an acidic or alkaline aqueous dispersion of FeOOH particles which has been manufactured according to known methods. According to the invention, a water-soluble ammonium salt, which is derived from a low-molecular weight, weakly acidic organic acid and which volatilizes either as such or after decomposition not greater than 450 DEG C., is added to the aqueous dispersion. As a result of the addition of the ammonium salt, the FeOOH pigment flocculates. It is then separated and washed with water which preferably is also provided with the ammonium salt. According to a further embodiment of the invention the resulting pigment which, after drying, has a very low salt content, is converted into an Fe pigment or a gamma Fe2O3 pigment which also has a very low salt content. A magnetic recording element which is based on the Fe or gamma -Fe2O3 pigment obtained according to the invention has improved life properties in particular when used or stored in a humid environment.</p> |
