Process for preparing foamed styrene polymers containing an inorganic pigment

Claim 1

A PROCESS FOR PREPARING FOAMED STYRENE POLYMERS WHICH COMPRISES EXTRUDING A FOAMABLE STYRENE POLYMER COMPOSITION AT A TEMPERATURE OF ABOUT 250-400*F., SAID FOAMABLE STYRENE POLYMER COMPOSITION CONSISTING ESSENTIALLY OF A FREE FLOWING UNIFORM PHYSICAL ADMIXTURE OF (A) A THERMOPLASTIC STYRENE POLYMER OF THE GROUP CONSISTING OF STYRENE HOMOPOLYMERS AND STYRENE INTERPOLYMERS CONTAINING AT LEAST 85 WEIGHT PERCENT OF STYRENE AND UP TO 15 WEIGHT PERCENT OF A VINYLIDENE MONOMER INTERPOLYMERIZABLE WITH STYRENE, SAID STYRENE POLYMER HAVING AN AVERAGE PARTICLE SIZE OF LESS THAN ABOUT 10 MESH, AND (B) A FINELY DIVIDED INORGANIC PIGMENT HAVING AN AVERAGE PARTICLE SIZE OF LESS THAN ABOUT 5 MICRONS AND HAVING ADSORBED ON THE SURFACE THEREOF, BASED UPON THE WEIGHT OF THE INORGANIC PIGMENT, AT LEAST ABOUT 25 WEIGHT PERCENT OF AN ALIPHATIC HYDROCARBON BOILING IN THE RANGE OF ABOUT 10-80*C., SAID STYRENE POLYMER AND INORGANIC PIGMENT BEING PRESENT IN SUCH PROPORTIONS THAT THE COMPOSITION CONTAINS ABOUT 5-10 PARTS OF THE ALIPHATIC HYDROCARBON PER 100 PARTS OF THE STYRENE POLYMER.