Hydrophobic silica

Abstract

Hydrophobic, pyrogenically produced silica having a tamped density of 55 to 200 g/l is produced by hydrophobizing pyrogenically produced silica and then compacting it. The silica may be used for the production of dispersions.

1 . A finely divided, readily dispersible hydrophobic, pyrogenically produced silica in the form of aggregates, having a tamped density of 55 to 200 g/l and which has been produced by a process comprising: 
 (1) hydrophobicizing by reaction of the silica with a halogen-free silane and    (2) compacting the silica by compacting means consisting of a roller compactor or a belt filter press.    
     
     
         2 . The finely divided, readily dispersible hydrophobic, pyrogenically produced silica according to  claim 1  having a tamped density of 60 to 200 g/l.  
     
     
         3 . (canceled)  
     
     
         4 . The hydrophobic, pyrogenically produced silica according to  claim 1  wherein said silica has a chloride content of less than or equal to 100 ppm.  
     
     
         5 .- 9 . (canceled)  
     
     
         10 . A dispersion of a hydrophobic, pyrogenically produced silica according to  claim 1.