Patent ID: 7015271

Claim:
A cured organic rubber article having dispersed therein from 10 to 150 parts per 100 parts of rubber of a hydrophobic particulate inorganic oxide selected from the group consisting of amorphous precipitated silica, alumina and mixtures of such inorganic oxides, said hydrophobic inorganic oxide being characterized by (a) a substantial absence of functional groups capable of chemically reacting with rubber, (b) a hydroxyl content of from 4–12 OH/nm 2 , (c) a carbon content of from 0.3 to 3 weight percent that is substantially non-extractable, (d) a methanol wettability of from 25 to 35 percent, (e) an M1 Standard White Area of less than 0.2 percent, and (f) a BET surface area of from 40 to 350 m 2 /g.