Heterophasic polypropylene resin with long chain branching

1. Heterophasic polypropylene resin having a MFR (2.16 kg, 230° C.) of at least 1.0 g/10 min, determined according to ISO 1133,

comprising

a propylene random copolymer matrix phase (A), and

an ethylene-propylene copolymer rubber phase (B) dispersed within the matrix phase,

wherein the heterophasic polypropylene resin has a fraction soluble in p-xylene at 25° C. (XCS fraction) being present in the resin in an amount of 15 to 45 wt % whereby the XCS fraction has an ethylene content of 25 wt % or lower, and

a fraction insoluble in p-xylene at 25° C. (XCU fraction),

said heterophasic polypropylene resin being characterised by a strain hardening factor (SHF) of 1.7 to 4.0 when measured at a strain rate of 3.0 s −1 and a Hencky strain of 3.0.

2. Heterophasic polypropylene resin having a MFR (2.16 kg, 230° C.) of at least 1.0 g/10 min determined according to ISO 1133, and having a tensile modulus of 450 MPa or lower when measured according to ISO 527-2 on an injection moulded test specimen of type 1A prepared according to ISO 1872-2 at a temperature of 23° C. and an elongation rate of 1 mm/min comprising

a propylene random copolymer matrix phase (A), and

an ethylene-propylene copolymer rubber phase (B) dispersed within the matrix phase,

wherein the heterophasic polypropylene resin has a fraction soluble in p-xylene at 25° C. (XCS fraction) being present in the resin in an amount of 15 to 45 wt % whereby the XCS fraction has an ethylene content of 25 wt % or lower and a molecular weight distribution Mw/Mn of 1.0 to 4.0; and

a fraction insoluble in p-xylene at 25° C. (XCU fraction).

3. The heterophasic polypropylene resin according to claim 1 , wherein the fraction soluble in p-xylene at 25° C. (XCS fraction) has a molecular weight distribution Mw/Mn of 1.0 to 4.0.

4. The heterophasic polypropylene resin according to claim 1 having a tensile modulus of 450 MPa or lower when measured according to ISO 527-2 on a compression moulded test specimen of type 1A prepared according to ISO 1872-2 at a temperature of 23° C. and an elongation rate of 1 mm/min.

5. The heterophasic polypropylene resin according to claim 1 , wherein the fraction soluble in p-xylene at 25° C. (XCS fraction) has a weight average molecular weight (M w ) of 180 to 250 kg/mol, measured by GPC according to ISO 16014-1 and -4.

6. The heterophasic polypropylene resin according to claim 1 , wherein the fraction insoluble in xylene (XCU fraction) includes a material formed from propylene and at least one comonomer selected from ethylene, and/or C 4 to C 12 alpha olefins.

7. The heterophasic polypropylene resin according to claim 6 , wherein the amount of units derived from comonomers selected from ethylene, and/or C 4 to C 12 alpha olefins in the fraction insoluble in xylene (XCU fraction) is 1.5 to 5.0 wt.-% with respect to the total weight of the fraction being insoluble in p-xylene (XCU fraction).

8. The heterophasic polypropylene resin according to claim 1 having a melting temperature (T m ) of 133 to 150° C.

9. The heterophasic polypropylene resin according to claim 1 having a Charpy notched impact strength at 23° C. of at least 90 kJ/m 2 and/or a Charpy notched impact strength at −20° C. of at least 10 kJ/m 2 , determined according to ISO 179-1/1eA.

10. The heterophasic polypropylene resin according to claim 1 withstanding a maximum instrumented falling weight force at −20° C. of at least 250 N, determined according to ISO 6603-2.

11. An article comprising the heterophasic polypropylene resin according to claim 1 .

12. A process for producing a heterophasic polypropylene resin having a MFR (2.16 kg, 230° C.) of at least 1.0 g/10 min, determined according to ISO 1133,

comprising

a propylene random copolymer matrix phase (A), and

an ethylene-propylene copolymer rubber phase (B) dispersed within the matrix phase,

wherein the heterophasic polypropylene resin has a fraction soluble in p-xylene at 25° C. (XCS fraction) being present in the resin in an amount of 15 to 45 wt % whereby the XCS fraction has an ethylene content of 25 wt % or lower, and

a fraction insoluble in p-xylene at 25° C. (XCU fraction),

said heterophasic polypropylene resin being characterised by a strain hardening factor (SHF) of 1.7 to 4.0 when measured at a strain rate of 3.0 s −1 and a Hencky strain of 3.0,

by using the same catalyst for the production of the matrix phase and the dispersed phase.

13. Process according to claim 12 , wherein the catalyst is capable of producing a fraction being soluble in p-xylene at 25° C. having a molecular weight distribution Mw/Mn of 1.0 to 4.0.

14. Process according to claim 12 , wherein the catalyst is a single site catalyst of formula of formula (I)

(L) m R n MX q   (I)

wherein

M is a transition metal of group 3 to 10 or the periodic table (IUPAC), or of an actinide or lantanide,

each X is independently a monovalent anionic ligand, such as σ-ligand,

each L is independently an organic ligand which coordinates to M,

R is a bridging group linking two ligands L,

m is 2 or 3,

n is 0 or 1,

q is 1, 2 or 3,

m+q is equal to the valency of the metal, and

with the proviso that at least two ligands “L” are of different chemical structure.

15. Process according to claim 12 , wherein the heterophasic polypropylene resin is produced in a multistage process involving at least two reactors, whereby one reactor is operated with a C3/C2 weight ratio of from 68/32 to 90/10.