β-nucleated polypropylene composition

1. Polypropylene composition comprising

(a) an isotactic propylene homopolymer (A) and

(b) a random propylene-butene copolymer (B) with a 1-butene content up to 8 wt.-% or a random propylene-ethylene copolymer (B′) with an ethylene content not exceeding 3.0 wt %

wherein the amount of β-modification of the polypropylene composition is at least 50%.

2. Polypropylene composition according to claim 1 , wherein the isotactic propylene homopolymer (A) has MFR 2 (230° C.) of not more than 5.0 g/10 min measured according ISO 1133.

3. Polypropylene composition according to claim 1 , wherein the copolymer (B) or copolymer (B′) has MFR 2 (230° C.) of not more than 5.0 g/10 min measured according ISO 1133.

4. Polypropylene composition according to claim 1 , wherein the polypropylene composition comprises

(a)

(i) 30 to 70 wt.-% propylene homopolymer (A) based on homopolymer (A) and random copolymer (B) (Homopolymer (A)/(homopolymer (A)+copolymer (B)) and

(ii) 70 to 30 wt.-% random propylene-butene copolymer (B) based on homopolymer (A) and random copolymer (B) (homopolymer (A)/(homopolymer (A)+copolymer (B))

or

(b)

(i) 30 to 70 wt.-% propylene homopolymer (A) based on homopolymer (A) and random copolymer (B′) (homopolymer (A)/(homopolymer (A)+copolymer (B′)) and

(ii) 70 to 30 wt.-% random propylene-butene copolymer (B) based on homopolymer (A) and random copolymer (B) (homopolymer (A)/(homopolymer (A)+copolymer (B)).

5. Polypropylene composition according to claim 1 , wherein the polypropylene composition comprises up to 5.0 wt.-% comonomer, preferably up to 5.0 wt.-% 1-butene or ethylene.

6. Polypropylene composition according to claim 1 , wherein the polypropylene composition has a xylene soluble fraction according to ISO 6427 of less than 5 wt.-%.

7. Polypropylene composition according to claim 1 , wherein the polypropylene composition has MFR 2 (230° C.) of not more than 0.8 g/10 min measured according ISO 1133.

8. Polypropylene composition according to claim 1 , wherein the polypropylene composition in a compression molded state has a flexural modulus measured according to ISO 178 of at least 1300 Mpa.

9. Polypropylene composition according to claim 1 , wherein the polypropylene composition in a compression molded state has an impact strength measured according the Charpy impact test (ISO 179 (1 eA)) at 23° C. of at least 9.5 kJ/m 2 and/or an impact strength measured according the Charpy impact test (ISO 179 (1 eA)) at −20° C. of at least 2.5 kJ/m 2 .

10. Use of a polypropylene composition according to claim 1 for the manufacture of pipes or cables.

11. Use of a polypropylene composition according to claim 1 as part of a pipe or a cable.

12. Polypropylene composition according to claim 1 , wherein the polypropylene composition has been produced in a multistage process.

13. Polypropylene composition according to claim 12 , wherein the propylene homopolymer (A) is produced in a loop reactor and subsequently the copolymer (B) or the copolymer (B′) is produced in a gas phase reactor.

14. A process for the manufacture of a polypropylene composition comprising,

providing a polypropylene composition having

(a) an isotactic propylene homopolymer (A) and

(b) a random propylene-butene copolymer (B) with a 1-butene content up to 8 wt.-% or a random propylene-ethylene copolymer (B′) with an ethylene content not exceeding 3.0 wt %

wherein the amount of β-modification of the polypropylene composition is at least 50%; and

wherein the polypropylene composition is produced in a multistage process and subsequently treated with a β-nucleating agent.

15. Process according to claim 14 , wherein the propylene homopolymer (A) is produced in a loop reactor and subsequently the copolymer (B) or the copolymer (B′) is produced in a gas phase reactor.

16. Pipe or cable comprising, a polypropylene composition having

(a) an isotactic propylene homopolymer (A) and

(b) a random propylene-butene copolymer (B) with a 1-butene content up to 8 wt.-% or a random propylene-ethylene copolymer (B′) with an ethylene content not exceeding 3.0 wt %

wherein the amount of β-modification of the polypropylene composition is at least 50%.

17. Pipe according to claim 16 , wherein the pipe is a pressure pipe.

18. Process for the manufacture of a pipe or cable comprising,

providing a polypropylene composition having

(a) an isotactic propylene homopolymer (A) and

(b) a random propylene-butene copolymer (B) with a 1-butene content up to 8 wt.-% or a random propylene-ethylene copolymer (B′) with an ethylene content not exceeding 3.0 wt %

wherein the amount of β-modification of the polypropylene composition is at least 50%; and

wherein a melt of the polypropylene composition is extruded and subsequently formed to a pipe or surrounds a conductor(s).