| 摘要 |
<p>Process for preparing an aqueous dispersion which has a pH of 9 to 14 and comprises particles of a pyrogenic titanium- silicon mixed oxide powder having a proportion of silicon dioxide of 75 to 99.99% by weight and of titanium dioxide of 0.01 to 25% by weight, whose mean aggregate diameter in the dispersion is not more than 200 nm, and at least one basic, quaternary ammonium compound.</p> |
