Production of powdery, filler-containing rubber mixtures and the use thereof in the manufacture of tire treads

Claim 1

A PROCESS FOR THE PREPARATION OF DISCRETE, POURABLE, POWDERY, NON-CAKING FILLER-CONTAINING ELASTOMER PARTICLES HAVING AN ABERAGE DIAMETER OF 10-1000U, WHICH COMPRISES: A. ADMIXING I) A SOLUTION OF AN ELASTOMERIC POLYMER, SAID ELASTOMERIC POLYMER HAVING A SOLUTION VISCOSITY OF 1-7 DL/GM. AMD BEING SELECTED FROM THE GROUP CONSISTING OF POLYBUTADIENES HAVING A VINYL GROUP CONTENT OF FROM 8 TO 50% AND COPOLYMERS OF BUTADIENE WITH 10-60% BY WEIGHT STYRENE IN WHICH THE VINYL GROUP CONTENT IN THE POLYBUTADIENE PRESENT IS FROM 8 TO 30% IN A VOLATILE, INERT ORGANIC SOLVENT WHIEH SOLVENT HAS AN ATMOSPHERIC PRESSURE BOILING POINT OF ABOUT -5* TO +85*C., WITH II) 25-250 PARTS BY WEIGHT PER 100 PARTS BY WEIGHT OF SAID PPLYMER OF A SOLID, FINELY DIVIDED ELASTOMER FILLER SELECTED FROM THE GROUP CONSISTING OF SILICIC ACID AND CARBON BLACK TO FORM A HOMOGENEOUS FLUID MIXTURE CONSISTING ESSENTIALLY OF SAID FILLER AND SAID ELASTOMER SOLUTION: AND B. EXPANDING SAID HOMOGENEOUS FLUID MIXTURE FROM A HIGHER PRESSURE AND AN INITIAL TEMPERATURE OF 50*-280* C. AT WHICH SAID SOLVENT IS IN THE LIQUID PHASE ACROSS A PRESSURE DIFFERENTIAL OF ABOUT 5-20 ATMOSPHERES TO A LOWER PRESSURE AT WHICH SAID SOLVENT FLASH EVAPORATES TO FORM SAID FILLER-CONTAINING ELASTOMER PARTICLES HAVING A RESIDUAL SOLVENT CONTENT OF LESS THAN ABOUT 1% BY WEIGHT.