High flow polyolefin composition with high stiffness and toughness

1. A polyolefin composition comprising

(a) a first heterophasic propylene copolymer (HECO1) having

(i) a melt flow rate MFR 2 (230° C.) measured according to ISO 1133 in the range of 15.0 to 55.0 g/10 min, and

(ii) a xylene cold soluble content (XCS) determined according ISO 16152 (25° C.) in the range of 24 to 38 wt.-%,

wherein further

(iii) the intrinsic viscosity (IV) determined according to DIN ISO 1628/1 (in decalin at 135° C.) of the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (HECO1) is in the range of 2.0 to 3.5 dl/g, and

(b) a second heterophasic propylene copolymer (HECO2) having

(i) a melt flow rate MFR 2 (230° C.) measured according to ISO 1133 in the range of 0.5 to 8.0 g/10 min, and

(ii) a xylene cold soluble content (XCS) determined according ISO 16152 (25° C.) in the range of 33 to 55 wt.-%,

wherein further

(iii) the intrinsic viscosity (IV) determined according to DIN ISO 1628/1 (in decalin at 135° C.) of the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (HECO2) is in the range of 1.5 to 2.6 dl/g,

wherein the polyolefin composition comprises the first heterophasic propylene copolymer (HECO1) and the second heterophasic propylene copolymer (HECO2) in a weight ratio [(HECO1):(HECO2)] of 6:1 to 99:1, and HECO1 and HECO2 make up at least 95 wt.-%, of the polyolefin composition, the remaining part being additives or additional polymers utilized as carrier for the additives.

2. The polyolefin composition according to claim 1 , wherein the ratio of the melt flow rate MFR 2 (230 ° C.) of the first heterophasic propylene copolymer (HECO1) to the second heterophasic propylene copolymer (HECO2) fulfills the in-equation (I),

MFR

⁡

(

1

)

MFR

⁡

(

2

)

≥

5

,

(

I

)

wherein

MFR (1) is the melt flow rate MFR 2 (230 ° C.) of the first heterophasic propylene copolymer (HECO1) and

MFR (2) is the melt flow rate MFR 2 (230 ° C.) of the second heterophasic propylene copolymer (HECO2).

3. The polyolefin composition according to claim 1 , wherein

(i) the first heterophasic propylene copolymer (HECO1) has a comonomer content in the range of 6.0 to 17.0 wt.-%, and/or

(ii) the comonomer content of the xylene cold soluble (XCS) fraction of the first heterophasic propylene copolymer (HECO1) is in the range of 26 to 40 wt.-%.

4. The polyolefin composition according to claim 1 , wherein

(i) the second heterophasic propylene copolymer (HECO2) has a comonomer content in the range of 10.0 to 30.0 wt.-%, and/or

(ii) the comonomer content of the xylene cold soluble (XCS) fraction of the second heterophasic propylene copolymer (HECO2) is in the range of 10 to 30 wt.-%.

5. The polyolefin composition according to claim 1 , wherein the first heterophasic propylene copolymer (HECO1) comprises a polypropylene (PP1) as matrix and an elastomeric propylene copolymer (E1) dispersed in the matrix.

6. The polyolefin composition according to claim 1 , wherein the second heterophasic propylene copolymer (HECO2) comprises a propylene copolymer (R-PP2) as matrix and an elastomeric propylene copolymer (E2) dispersed in the matrix.

7. The polyolefin composition according to claim 1 , wherein

(i) the first heterophasic propylene copolymer (HECO1) has a melting temperature Tm in the range of 135 to 168° C., and/or

(ii) the second heterophasic propylene copolymer (HECO2) has a melting temperature Tm in the range of 140 to 155° C.

8. An automotive article comprising at least 60 wt.-% of the polyolefin composition according to claim 1 .

9. The automotive article according to claim 8 , wherein the automotive article is selected from the group consisting of bumpers, side trims, step assists, body panels, spoilers, dashboards, and interior trims.

10. The polyolefin composition according to claim 5 , wherein

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

(ii) the polypropylene (PP1) has a melt flow rate MFR 2 (230° C.) measured according to ISO 1133 of 60 to 400 g/10 min.

11. The polyolefin composition according to claim 2 , wherein

(i) the first heterophasic propylene copolymer (HECO1) has a comonomer content in the range of 6.0 to 17.0 wt.-%, and/or

(ii) the comonomer content of the xylene cold soluble (XCS) fraction of the first heterophasic propylene copolymer (HECO1) is in the range of 26 to 40 wt.-%.

12. The polyolefin composition according to claim 2 , wherein

(i) the second heterophasic propylene copolymer (HECO2) has a comonomer content in the range of 10.0 to 30.0 wt.-%, and/or

(ii) the comonomer content of the xylene cold soluble (XCS) fraction of the second heterophasic propylene copolymer (HECO2) is in the range of 10 to 30 wt.-%.

13. The polyolefin composition according to claim 2 , wherein the first heterophasic propylene copolymer (HECO1) comprises a polypropylene (PP1) as matrix and an elastomeric propylene copolymer (E1) dispersed in the matrix.

14. The polyolefin composition according to claim 2 , wherein the second heterophasic propylene copolymer (HECO2) comprises a propylene copolymer (R-PP2) as matrix and an elastomeric propylene copolymer (E2) dispersed in the matrix.

15. The polyolefin composition according to claim 14 , wherein the propylene copolymer (R-PP2) has

(i) a comonomer content of 3.0 to 11.0 wt.-%, wherein the comonomers are ethylene and/or a C 4 to C 12 α-olefin, and/or

(ii) a melt flow rate MFR 2 (230° C.) measured according to ISO 1133 in the range of 0.1 to 10 g/10 min.

16. The polyolefin composition according to claim 2 , wherein

(i) the first heterophasic propylene copolymer (HECO1) has a melting temperature Tm in the range of 135 to 168° C., and/or

(ii) the second heterophasic propylene copolymer (HECO2) has a melting temperature Tm in the range of 140 to 155° C.