Patent ID: 6183658
Filing Date: 2001-02-06
Classification: B82Y,C01G,C01P,C09C,Y10T

Abstract:
A process for producing an-agglomerate-free suspension of stably coated nanosize iron-containing oxide particles, comprising the following steps in the order indicated:(1) preparing an aqueous suspension of nanosize iron-containing oxide particles which are partly or completely present in the form of agglomerates;(2) adding (i) a trialkoxysilane which has a hydrocarbon group which is directly bound to Si and to which is bound at least one group selected from amino, carboxyl, epoxy, mercapto, cyano, hydroxy, acrylic, and methacrylic, and (ii) a water-miscible polar organic solvent whose boiling point is at least 10.degree. C. above that of water;(3) treating the resulting suspension with ultrasound until at least 70% of the particles present have a size within the range from 20% below to 20% above the mean particle diameter;(4) removing the water by distillation under the action of ultrasound; and(5) removing the agglomerates which have not been broken up.