Process for the preparation of copolymers of propylene

A process for the preparation of a copolymer of propylene and ethylene comprising:

• (A) polymerising propylene and optionally ethylene in bulk to form a propylene homopolymer component or propylene-ethylene random copolymer component in the presence of a solid particulate catalyst free from an external carrier comprising:
• (i) a symmetrical complex of formula (I):
• wherein
• M is zirconium or hafnium;
• each X is a sigma ligand;
• L is a divalent bridge selected from —R′2C—, —R′2C—CR′2—, —R′2Si—, —R′2Si—SiR′2—, —R′2Ge—, wherein each R′ is independently a hydrogen atom, C1-C20-alkyl, tri(C1-C20-alkyl)silyl, C6-C20-aryl, C7-C20-arylalkyl or C7-C20-alkylaryl;
• R2 is a C1-C20 hydrocarbyl radical;
• m is 2 to 5;
• each R9 is a H or C1-C20 hydrocarbyl radical;
• R7 is a hydrogen atom or a C1-10-hydrocarbyl radical;
• n is 0 to 3;
• R1 is a C1-C20 hydrocarbyl radical and optionally two adjacent R1 groups taken together can form a further mono or multicyclic ring condensed to Ph ring optionally substituted by one or two groups R4;
• and
• R4 is a C1-C10 alkyl radical;
• and (ii) a cocatalyst;
• (B) polymerising propylene and ethylene in the gas phase in the presence of the polymer prepared in step (A) and in the presence of the catalyst from step (A) so as to form a propylene ethylene copolymer component;
• wherein the xylene soluble fraction of the copolymer of propylene and ethylene has an ethylene content of at least 10 wt % and a intrinsic viscosity of at least 1.2 dl/g.

A process for the preparation of a copolymer of propylene and ethylene comprising:

• (A) polymerising propylene and optionally ethylene in bulk to form a propylene homopolymer component or a propylene ethylene random copolymer component in the presence of a solid particulate catalyst free from an external carrier comprising:
• (i) a symmetrical complex of formula (I):
• wherein
• M is zirconium or hafnium;
• each X is a sigma ligand;
• L is a divalent bridge selected from —R′2C—, —R′2C—CR′2—, —R′2Si—, —R′2Si—SiR′2—, —R′2Ge—, wherein each R′ is independently a hydrogen atom, C1-C20-alkyl, tri(C1-C20-alkyl)silyl, C6-C20-aryl, C7-C20-arylalkyl or C7-C20-alkylaryl;
• R2 is a C1-C20 hydrocarbyl radical;
• m is 2 to 5;
• each R9 is a H or C1-C20 hydrocarbyl radical;
• R7 is a hydrogen atom or a C1-10-hydrocarbyl radical;
• n is 0 to 3;
• R1 is a C1-C20 hydrocarbyl radical and optionally two adjacent R1 groups taken together can form a further mono or multicyclic ring condensed to Ph ring optionally substituted by one or two groups R4;
• and
• R4 is a C1-C10 alkyl radical;
• and (ii) a cocatalyst;
• (B) polymerising propylene and optionally ethylene in the gas phase in the presence of the polymer prepared in step (A) and in the presence of the catalyst from step (A) so as to form a propylene homopolymer or propylene ethylene copolymer component;
• (C) polymerising propylene and ethylene in the gas phase in the presence of the polymer prepared in step (B) and in the presence of the catalyst from step (B) so as to form a propylene ethylene copolymer component;
• wherein the xylene soluble fraction of the copolymer of propylene and ethylene has an ethylene content of at least 10 wt % and a intrinsic viscosity of at least 1.2 dl/g.