| 摘要 |
<p>1504977 Hydrophobic silica DEUTSCHE GOLDUND SILBER-SCHEIDEANSTALT 22 May 1975 [25 July 1974] 22182/75 Heading C1A A finely-divided hydrophobic silica or silicate is made by a process which comprises precipitating an alkali metal silicate solution with a mineral acid or a metal salt solution, followed by addition of a prepolycondensed (mixture of) organo halogen silane(s) to the suspension, filtering off the product, washing and drying it and subjecting it to a heat treatment at 300-400‹ C. A pre-polycondensed mixture of dimethyl dichlorosilane and methyl trichlorosilane is preferably added to the suspension at a temperature of 50-90‹ C.</p> |
