Reduced die lip buildup extrusion of polymer compositions

Process for die extrusion of melted polymers that reduces die lip buildup and its deleterious effects. Direct extrusion of mixed polymer pellets and filler concentrate pellets in one embodiment avoids a precompounding step and reduces the tendency of polymer and filler particles to adhere to the exit portion of the die. In other embodiments a reduced die lip radius and lower melt processing temperatures further enhance the benefits obtained. For co-extruded muitilayer film embodiments elimination of fillers and antiblock additives in skin layers add to the levels of die lip buildup reduction obtained. Hours of continuous operation without excessive die lip buildup in one arrangement have been increased from a level of 4 to 6 hours, for example, to in excess of 20 hours. Reduced product defect levels have also been attained.