| abstract |
The invention relates to a process for producing a free-flowing, silica-filled powder rubber by methods known per se, using a silica which has the following properties: 1. SiO2 content: 82 to 91.5% by weight, 2. metal oxides 0, 5 to 3% by weight, 3rd loss on ignition (DIN 55 921/2 - measured at 1 000 ° C): 5 to 15% by weight, 4th moisture (DIN 53 198 - measured at 105 ° C): 2 to 10 wt .-%, 5. surface area of the primary particles according to BET: 40 to 250 m² / g, 6. DBP absorption (ASTM D 2414-79) based on the weighed weight: 170 to 290%, 7. linear mean of Number distribution of the secondary particles: 10 to 2,000 nm, 8. Linear mean of the volume distribution of the secondary particles: 3 to 30 µm, 9. Share of secondary particles with a diameter of <1 µm; 0.01 to 5 wt .-% - the numbers of parameters 1 to 3 must add up to 100 wt .-%. |