Internal mixer silica compounds

Silica compounds are generally processed in conventional internal mixers, preferably with intermeshing rotors. These mixers are designed and optimized for carbon black-fiUed compounds in which mixing is based only on physical processes. When a silica-silane reinforcing system is used, additionally a chemical reaction, the sUanization, occurs. One of the main influencing factors of the silanization reaction is the concentration of ethanol in the compound as well as in the mixer [25,26]. As the silanization finally reaches an equilibrium, low concentrations of ethanol in the compound are expected to enhance the reaction rate. 

Mechanical Mixing of PFAP(II) Compounds. PFAP(II) O-ring seal formulations were mixed in a Brabender internal mixer equipped with a mixer head of 85-mL volume and cam-type blades. The mix order was as follows (1) PFAP(II), (2) silica (Quso WR82, silane-treated surface) (3) magnesium oxide and (4) bis(8-oxyquinolate)zinc(II). This compound then was placed on a small two-roll rubber mill (2 in. X 6 in.) and dicumyl peroxide was mixed in at 57°C. 

An overview of the mixing machinery cmrently available for the manufacture of silica compounds and the requirements for the design of an internal mixer for the production of these compotmds is presented. A comparison is made of different mixers and the replacement of a 270-litre tangential mixer with a250-litre intermeshing mixer to make use of the advantages of mtermeshing irrtemal rrrixers is demonstrated. 12 refs. (International Tyre Exhibition Conference, Akron, USA, Sept. 12-14, 2000). 

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