Process for preparing a polyolefin composition

A process for continuously preparing a polyolefin composition comprising polyolefin and carbon black in an extruder device, the process comprising the steps

• (i) supplying polyolefin in form of a polyolefin powder to a mixing device;
• (ii) measuring a flow rate of the polyolefin pellets prepared in the extruder device;
• (iiia) transferring carbon black powder from a storage vessel through a first carbon black discharge valve to a carbon black feeding vessel;
• (iiib) subsequently transferring the carbon black powder from the carbon black feeding vessel through a second carbon black discharge valve by gravity to a dosing device;
• and
• (iiic) subsequently transferring the carbon black powder from the dosing device to the mixing device.
• (iv) optionally supplying one or more further additives to the mixing device;
• (v) adjusting the flow rate of the polyolefin powder to the mixing device in response to the measured flow rate of the polyolefin pellets and either keeping the flow rates of the carbon black powder and the optionally supplied one or more further additives supplied to the mixing device constant or also adjusting the flow rates of the carbon black powder and the optionally supplied one or more further additives supplied to the mixing device in response to the measured flow rate of the polyolefin pellets;
• (vi) mixing the polyolefin powder, the carbon black powder and the optionally supplied one or more further additives to form a powder mixture,
• (vii) transferring the powder mixture obtained in step (vi) from the mixing device into the extruder device;
• (viii) heating the powder mixture to form a melt and homogenizing the melt within the extruder device to form a polyolefin composition in liquid state;
• and
• (ix) pelletizing the polyolefin composition.

A process for continuously preparing a polyolefin composition comprising polyolefin and carbon black in an extruder device, the process comprising the steps

• (i) supplying polyolefin in form of a polyolefin powder to a mixing device;
• (ii) measuring a flow rate of the polyolefin pellets prepared in the extruder device;
• (iii) supplying carbon black powder to the mixing device;
• (iv) optionally supplying one or more further additives to the mixing device;
• (v) adjusting the flow rate of the polyolefin powder to the mixing device in response to the measured flow rate of the polyolefin pellets and either keeping the flow rates of the carbon black powder and the optionally supplied one or more further additives supplied to the mixing device constant or also adjusting the flow rates of the carbon black powder and the optionally supplied one or more further additives supplied to the mixing device in response to the measured flow rate of the polyolefin pellets;
• (vi) mixing the polyolefin powder, the carbon black and the optionally supplied one or more further additives to form a powder mixture,
• (vii) transferring the powder mixture obtained in step (vi) from the mixing device into the extruder device;
• (viii) heating the powder mixture to form a melt and homogenizing the melt within the extruder device to form a polyolefin composition in liquid state;
• (ix) pelletizing the polyolefin composition;
• (x) supplying polyolefin pellets to the extruder device;
• and
• (xi) adjusting the flow rate of the polymer pellets fed to extruder device in response to the measured flow rate of the polyolefin pellets.