Process for recycling propylene-ethylene copolymers

A process for recycling propylene-ethylene copolymers comprising the steps of:

• a) polymerizing propylene and ethylene in the presence of a single site catalyst in a continuous polymerization reactor under dynamic conditions,
• b) collecting a propylene-ethylene copolymer obtained in step a) comprising at least two fractions of propylene-ethylene copolymer powders (P1, P2) to obtain a propylene-ethylene copolymer mixture (M) having a MFR2 (ISO 1133, 230° C., 2.16 kg) in a range of from 1.5 to 80.0 g/10 min and an ethylene content in a range of from 1.0 to 4.0 wt. % based on the total weight of the mixture (M),
• c) compounding said mixture (M) in an extruder in the presence of a radical initiator, and a clarifying agent in an amount of from 0.01 to 1.0 wt. %, based on the total weight of the mixture of propylene-ethylene copolymer powders, and
• d) extruding the above mixture into pellets;
• wherein, in step a), the dynamic conditions are such that the ethylene content and the melt flow rate (MFR2) of the resulting copolymer gradually changes from a first predetermined ethylene content, E1, to a second predetermined ethylene content, E2, and/or from a first predetermined melt flow rate, MFR2-1, to a second predetermined melt flow rate, MFR2-2;
• wherein collecting the copolymer powders in step b) is started when the polymer produced in step a) has a first ethylene content, E1, and a melt flow rate MFR2-1, and collecting the copolymer powders in step b) is stopped when the polymer produced in step a) has a second ethylene content E2 and a melt flow rate MFR2-2;
• and
• wherein the propylene-ethylene copolymer pellets obtained in step d) have:
• i) a MFR2 (ISO 1133, 230° C., 2.16 kg) in the range of from 20 to 120 g/10 min,
• ii) a ratio of MFR2 pellets/MFR2 powder >1
• iii) an ethylene content in a range of from 1.0 to 4.0 wt %,
• iv) a crystallization temperature Tc, determined by DSC according to ISO 11357-3:1999 in the range of from 100 to 125° C., and
• v) a flexural modulus, determined in a 3-point-bending according to ISO 178 on injection molded specimens of 80×10×4 mm, prepared in accordance with EN ISO 1873-2, of 850 MPa or more.