Talc containing polypropylene composition with excellent thermomechanical properties

1. A polypropylene composition consisting of

55 to 79 wt % base polymer mix;

18 to 44.5 wt % talc; and

0.5 to 3 wt % additives

based on the total weight of the polypropylene composition,

the base polymer mix containing a XCU fraction and a XCS fraction and the XCU fraction being present in an amount of 91 to 98 wt % and the XCS fraction being present in an amount of 2 to 9 wt %;

the base polymer mix containing a comonomer content of less than 5 wt % with respect to the base polymer mix;

the talc having a d50 median particle size of 1.0 to 3.0 μm when measured according to ISO 13317-3 15 using a Sedigraph; and

the composition having a MFR (230° C./2.16 kg; ISO 1133) of 1 to 10 g/10 min;

wherein the base polymer mix is obtained by blending:

homopolymer (A) having an MFR (230° C./2.16 kg; ISO 1133) of 0.3 to 2 g/10 min;

heterophasic polymer (B) having a flexural modulus of more than 850 MPa; and

homopolymer (C) having an MFR (230° C./2.16 kg; ISO 1133) of more than 10 g/10 min.

2. A polypropylene composition according to claim 1 , wherein the talc has a d95 cutoff particle size of 4.5 to 7.5 μm when measured according to ISO 13317-3 using a Sedigraph.

3. A polypropylene composition according to claim 2 , wherein the talc has a specific surface area of 7.5 to 9 m2/g determined as the BET surface according to DIN 66131/2.

4. A polypropylene composition according to claim 2 , wherein the tensile modulus/talc ratio is more than 110 MPa/wt % when the tensile modulus is measured according to ISO 527-2 and the weight of the talc is based on the total weight of the polypropylene composition.

5. A polypropylene composition according to claim 2 , wherein the flexural modulus/talc ratio is more than 113 MPa/wt % when the flexural modulus is measured according to ISO 178 and weight of talc is based on the total weight of the polypropylene composition.

6. A polypropylene composition according to claim 2 , wherein the maximum force in the Instrumented Puncture Test at 0° C. is more than 800 N when measured according to ISO 6603-2.

7. A polypropylene composition according to claim 2 , wherein the composition having a MFR (230° C./2.16 kg; ISO 1133) of 2.1 to 3.5 g/10 min.

8. A polypropylene composition according to claim 1 , wherein the talc has a specific surface area of 7.5 to 9 m2/g determined as the BET surface according to DIN 66131/2.

9. A polypropylene composition according to claim 1 , wherein the base polymer mix is obtained by blending

50 to 65 wt % homopolymer (A);

20 to 32 wt % heterophasic polypropylene (B) having an MFR (230° C./2.16 kg; ISO 1133) of 5 to 20 g/10 min; and

10 to 20 wt % homopolymer (C)

based on the total weight of the base polymer mix.

10. A polypropylene composition according to claim 9 , wherein the heterophasic polypropylene (B) has a XCS content of 25 to 39 wt %.

11. A polypropylene composition according to claim 9 , wherein the XCS fraction of the heterophasic polypropylene (B) has an intrinsic viscosity of 2.1 to 2.9 dl/g when measured in decalin at 135° C. according to DIN EN ISO 1628-1 and -3.

12. A polypropylene composition according to claim 9 , wherein the homopolymer (C) is a nucleated homopolymer.

13. A polypropylene composition according to claim 1 , wherein the tensile modulus/talc ratio is more than 110 MPa/wt % when the tensile modulus is measured according to ISO 527-2 and the weight of the talc is based on the total weight of the polypropylene composition.

14. A polypropylene composition according to claim 1 , wherein the flexural modulus/talc ratio is more than 113 MPa/wt % when the flexural modulus is measured according to ISO 178 and weight of talc is based on the total weight of the polypropylene composition.

15. A polypropylene composition according to claim 1 , wherein the maximum force in the Instrumented Puncture Test at 0° C. is more than 800 N when measured according to ISO 6603-2.

16. A polypropylene composition according to claim 1 , wherein the composition having a MFR (230° C./2.16 kg; ISO 1133) of 2.1 to 3.5 g/10 min.

17. A polypropylene composition according to claim 1 , wherein the heterophasic polypropylene (B) is produced in 4 sequential reactors.

18. A polypropylene composition according to claim 17 , wherein the 4 sequential reactors are a combination of one loop reactor and tree gas phase reactors coupled in series.

19. A polypropylene composition according to claim 18 , wherein the production of the heterophasic polypropylene (B) involves

the preparation of a first polymer in a loop reactor having an MFR (230° C./2.16 kg; ISO 1133) of 50 to 60 g/10 min;

transferring the product to a first gas phase reactor for the preparation of a second polymer having an MFR (230° C./2.16 kg; ISO 1133) of 50 to 60 g/10 min;

transferring the product to a second gas phase reactor for the preparation of a third polymer having an MFR (230° C./2.16 kg; ISO 1133) of 10 to 25 g/10 min; and

transferring the product to a third gas phase reactor for the preparation of the heterophasic polypropylene (B) having an MFR (230° C./2.16 kg; ISO 1133) of 5 to 20 g/10 min and a flexural modulus of more than 850 MPa when measured according to ISO 178.

20. An article made from the polypropylene composition according to claim 1 .

21. Process for the production of a polypropylene composition by blending 55 to 79 wt % base polymer mix, 18 to 44.5 wt % talc, 0.5 to 3 wt % additives, based on the total weight of the polypropylene composition, whereby the base polymer mix is

50 to 65 wt % homopolymer (A) having an MFR (230° C./2.16 kg; ISO 1133) of 0.3 to 2 g/10 min;

20 to 32 wt % heterophasic polypropylene (B) having an MFR (230° C./2.16 kg;

ISO 1133) of 5 to 20 g/10 min and a flexural modulus of more than 850 MPa when measured according to ISO 178; and

10 to 20 wt % homopolymer (C) having an MFR (230° C./2.16 kg; ISO 1133) of more than 10 g/10 min

based on the total weight of the base polymer mix.