Process for producing a polymer composition

A process for producing a polymer composition comprising

• (A) a non-elastomeric polyethylene,
• (B) an elastomer, and
• (C) an acid grafting agent,
• comprising the steps of:
• feeding components (A), (B) and (C) into an extruder comprising a feeding section, a barrel section and a die plate, wherein the barrel section of the extruder downstream of the feeding section and upstream of the die plate is divided into a plurality of control zones, and the first control zone represents the first control zone within the barrel section downstream of the feeding zone in which the fed component(s)(A) and/or (B) start(s) to melt;
• compounding the components (A) and (B) in order to form the polymer composition;
• and
• grafting component (A) or components (A) and (B) with component (C) during the compounding step;
• characterized in that the process further comprises the step of
• independently controlling the temperature of each control zone of the plurality of control zones of the barrel section of the extruder as such that
• a) the temperature in the first control zone of the barrel section downstream of the feeding section is in the range of from higher than 85° C. to 180° C.,
• b) the temperature of the control zones of the barrel section from the first control zone of the barrel section downstream the feeding section to the control zone in the middle of the barrel section is increased over the length of the barrel section in two or more steps so that the temperature of the control zone in the middle of the barrel section is from 105% to 145% of the temperature in the first control zone of the barrel section downstream of the feeding section;
• and
• c) the temperature of the control zones of the barrel section from control zone in the middle of the barrel section to the control zone of the barrel section directly upstream of the die plate in maintained at the same temperature or increased to a temperature of not more than 120% of the temperature of the control zone in the middle of the barrel section.