| 摘要 |
<p>PURPOSE:To improve dispersibility by using a specified granular magnetic particle powder essentially comprising iron, and a low mol.wt. binder resin having specified weight average mol.wt. CONSTITUTION:A granular magnetic particle powder essentially comprising iron and having <=24ml/100g oil absorption and >56 compression ratio is mixed with a low mol.wt. binder resin having <150000 weight average mol.wt. The granular magnetic particle powder is obtd., for example, by effecting the reaction with iron (II) salt soln. and alkali soln., introducing oxygen-contg. gas into the obtd. suspension liquid containing Fe-contg. precipitate such as Fe(OH)2 or FeCO3, further oxidizing the obtd. particles, and treating the particles with a jet mill. Since the granular magnetic particle powder has small oil absorption, it has good mixing property with the binder resin. Moreover, even when the viscosity of the mixture of the powder with the binder resin is low because of the large compression ratio, a compacted body can be enough pulverized by mechanically shearing, so that excellent dispersibility is obtd.</p> |
