Heterophasic polypropylene copolymers

A process for the preparation of a heterophasic polypropylene copolymer comprising:

• (I) polymerising propylene and optionally ethylene and/or 1-butene in the presence of the catalyst so as to form:
• a1) a crystalline fraction (CF) comprising a propylene homopolymer or propylene copolymer with ethylene and/or with 1-butene having 0 to 3 wt % comonomer as said matrix component;
• and
• (II) subsequently polymerising additional propylene and ethylene and optionally 1-butene, in the presence of the matrix component of step (I) so as to form:
• a2) a propylene ethylene copolymer or propylene-ethylene-1-butene copolymer soluble fraction (SF) having a comonomer content of 12 to 45 wt %;
• wherein the crystalline fraction (CF) constitutes 55.0 to 95.0 wt % and the soluble fraction (SF) constitutes 5.0 to 45.0 wt % of the heterophasic propylene ethylene copolymer or heterophasic propylene ethylene 1-butene copolymer,
• wherein the amount of crystalline fraction (CF) and the amount soluble fraction (SF) are determined in 1,2,4-trichlorobenzene at 40° C.;
• and
• wherein the soluble fraction (SF) of the heterophasic propylene-ethylene copolymer or heterophasic propylene-ethylene-1-butene copolymer has an intrinsic viscosity IV (SF) in decalin at 135° C. of 2.5 to 11 dl/g;
• and said catalyst comprises (i) a metallocene complex, and (ii) a cocatalyst comprising a compound of a group 13 metal,
• wherein the metallocene complex is of formula (I):
• wherein
• each X is a sigma-ligand;
• in the group R2Si— at least one R is methyl or ethyl, and the other R is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl, pentyl, hexyl, cyclohexyl, and phenyl;
• each R1 independently is a CH2—R7 group, with R7 being H or linear or branched C1-6-alkyl group, C3-8 cycloalkyl group, or C6-10 aryl group;
• each R2 is independently a —CH═, —CY═, —CH2—, —CHY— or —CY2— group, wherein Y is a C1-6 hydrocarbyl group and where n is 2-6;
• each R3 and R4 independently is hydrogen, a linear or branched C1-6-alkyl group, a C7-20 arylalkyl, C7-20 alkylaryl group, C6-20 aryl group, or an —OY group, wherein Y is a is a C1-6 hydrocarbyl group;
• R5 is a linear or branched C1-6-alkyl group, C7-20 arylalkyl, C7-20 alkylaryl group or C6-20-aryl group;
• and
• R6 is a C (R8)3 group, with each R8 independently being a linear or branched C1-6 alkyl group;
• (A) wherein at least one R3 per phenyl group and at least one R4 is not hydrogen, and wherein at least one R3 per phenyl group and at least one R4 is hydrogen;
• or
• (B) wherein one R3 is an —OY group, wherein Y is a is a C1-6 hydrocarbyl group, in 4 position of each phenyl group and the two other R3 groups are tert-butyl groups;
• and/or
• (C) wherein one R4 is an —OY group, wherein Y is a C1-6 hydrocarbyl group, in 4-position of the phenyl ring and the two other R4 groups are tert-butyl groups.