Patent ID: 7629391
Filing Date: 2009-12-08
Classification: A61K,A61Q,C01B,C09D,C12H

Abstract:
1. A process for the preparation of an aqueous suspension of anionic colloidal silica having a neutral pH ranging from 6-8, which is stable for greater than six months and comprising individualized particles of colloidal silica which are not bound to one another by siloxane bonds, wherein an aqueous suspension of anionic colloidal silica comprising individualized particles of colloidal silica which are not bound to one another by siloxane bonds and having a pH in the range from 8.5 to 11, a specific surface in the range from 20 m 2 /g to 700 m 2 /g, a particle diameter in the range from 4 nm to 150 nm and having a percentage of silica of ≧5 parts by weight, is reacted with an aqueous suspension of anionic colloidal silica comprising individualized particles of colloidal silica which are not bound to one another by siloxane bonds having a pH in the range from 2 to 3.5, a specific surface in the range from 20 m 2 /g to 700 m 2 /g, a particle diameter in the range from 4 nm to 150 nm and having a percentage of silica of ≧5 parts by weight, further where the diameter of the particle is unchanged by the process.