Polypropylene composition with excellent surface appearance

1. A heterophasic polypropylene composition (HC) comprising a modified polypropylene composition (mPP), wherein said modified polypropylene composition (mPP) is obtained by treatment of a polypropylene composition (PP) with a peroxide (PO) and a crosslinking agent (CA), said polypropylene composition (PP) comprising:

i) a propylene polymer (PP1), and

ii) a plastomer (PL) being a copolymer of ethylene and at least one C4 to C20 α-olefin,

wherein;

said heterophasic polypropylene composition (HC) has a ratio XCS/XHU in the range of 0.6 to 2.6, wherein XCS is the xylene cold soluble content [in wt. %] of the heterophasic polypropylene composition (HC) and XHU is the xylene hot insoluble content [in wt. %] of the heterophasic polypropylene composition (HC),

and wherein

the weight ratio of the propylene polymer (PP1) and the plastomer (PL) [w(PP1)/w(PL)] in the modified polypropylene composition (mPP) is from above 1.0 to 3.0, wherein w(PP1) is the overall amount of the propylene polymer (PP1) (in wt. %) within the modified polypropylene composition (mPP) and w(PL) is the overall amount of the plastomer (PL) (in wt. %) within the modified polypropylene composition (mPP).

2. The heterophasic polypropylene composition (HC) according to claim 1 , having a xylene hot insoluble content (XHU) in the range of 11.0 to 25.0 wt. %.

3. The heterophasic polypropylene composition (HC) according to claim 1 , having a xylene cold soluble content (XCS) determined according ISO 16152 equal or below 29.0 wt. %.

4. The heterophasic polypropylene composition (HC) according to claim 1 , having a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 of at least 10.0 g/10 min.

5. The heterophasic polypropylene composition (HC) according to claim 1 , wherein the weight ratio of the propylene polymer (PP1) and the plastomer (PL) [w(PP1)/w(PL)] in the modified polypropylene composition (mPP) is from 1.1 to 1.8.

6. The heterophasic polypropylene composition (HC) according to claim 1 , wherein the polypropylene composition (PP) comprises:

i) at least 10.0 wt. % of the propylene polymer (PP1), and

ii) at least 5.0 wt. % of the plastomer (PL),

based on the overall amount of the polypropylene composition (PP).

7. The heterophasic polypropylene composition (HC) according to claim 1 , wherein the propylene polymer (PP1)

i) is a propylene homopolymer (H-PP1), and/or

ii) has a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 equal or below 35.0 g/10 min.

8. The heterophasic polypropylene composition (HC) according to claim 1 , wherein the propylene polymer (PP1) has:

i) a first polypropylene fraction (PP1a) having a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 5.0 to 20.0 g/10 min and

ii) a second polypropylene fraction (PP1b) having a melt flow rate MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 30.0 to 65.0 g/10 min.

9. The heterophasic polypropylene composition (HC) according to claim 1 , wherein the plastomer (PL) is a copolymer of ethylene and 1-butene or 1-octene.

10. The heterophasic polypropylene composition (HC) according to claim 1 , wherein the plastomer (PL) has:

(a) a melt flow rate MFR (190° C., 2.16 kg) measured according to ISO 1133 below 30 g/10 min,

(b) a comonomer content, based on the total weight of the plastomer (PL), in the range of 8.0 to 35.0 mol %, and

(c) a density below 0.880 g/cm 3 .

11. The heterophasic polypropylene composition (HC) according to claim 1 , wherein the peroxide (PO) is an alkyl or aryl peroxide.

12. The heterophasic polypropylene composition (HC) according to claim 1 , wherein the crosslinking agent is a compound of formula (I):

wherein M 2+ is a divalent metal ion and R 1 is hydrogen or methyl.

13. A moulded article, comprising the heterophasic polypropylene composition (HC) according to claim 1 .

14. A process for the preparation of the heterophasic composition (HC) according to claim 12 , wherein the polypropylene composition (PP) comprising the propylene polymer (PP1), the plastomer (PL) and optionally the propylene homopolymer (H-PP) is extruded in an extruder in the presence of the peroxide (PO) and the crosslinker (CA).