Tube made of a heterophasic polypropylene composition

1. An extruded tube comprising a heterophasic polypropylene composition comprising:

(a) a heterophasic polypropylene copolymer, and

(b) an antioxidant comprising a sterically hindered phenol,

wherein the heterophasic polypropylene copolymer fulfills the following features:

(i) the relative amount of crystalline polypropylene in the heterophasic polypropylene copolymer is above 20 wt % and less than 45 wt %,

(ii) the relative amount of xylene cold solubles (XCS) fraction, determined at 25° C. according to ISO 16152, in said heterophasic polypropylene copolymer is at least 10 wt %,

(iii) the relative content of isolated ethylene sequences (I(E)) of the XCS fulfills the equation:

I ( E )<78−1.97× C+ 0.015×( C ) 2   (I)

wherein C is the comonomer content [wt %] of the XCS fraction and wherein the I(E) content is defined by equation:

I

⁡

(

E

)

=

fPEP

(

fEEE

+

fPEE

+

fPEP

)

×

100

(

II

)

wherein

I(E) is the relative content of isolated to block ethylene sequences [in %];

fPEP is the mol fraction of propylene/ethylene/propylene sequences (PEP) in the sample;

fPEE is the mol fraction of propylene/ethylene/ethylene sequences (PEE) and of ethylene/ethylene/propylene sequences (EEP) in the sample;

fEEE is the mol fraction of ethylene/ethylene/ethylene sequences (EEE) in the sample wherein all sequence concentrations being based on a statistical triad analysis of 13 C-NMR data.

2. The extruded tube according to claim 1 wherein the heterophasic polypropylene copolymer has an ethylene content of the XCS, determined at 25° C. according to ISO 16152, of 32 to 70 wt %.

3. The extruded tube according to claim 1 wherein the heterophasic polypropylene copolymer has a total comonomer content defined as the sum of content of ethylene and α-olefins with 4-10 carbon atoms in the range of 7 to 26 wt %.

4. The extruded tube according to claim 1 wherein the heterophasic polypropylene copolymer fulfills the following features:

(iv) 90-70 wt % of xylene cold insoluble (XCI) fraction having an ethylene content in the range of 1.0 to 10.0 wt % and a relative content of isolated ethylene sequences (I(E)) of less than 20%, and

(v) 30-10 wt % of xylene cold soluble (XCS) from fraction, determined at 25° C. according to ISO 16152, having an ethylene content in the range of 30 to 60 wt % and a relative content of isolated ethylene sequences (I(E)) of less than 45%.

5. The extruded tube according to claim 1 wherein the heterophasic polypropylene copolymer fulfills the following features:

(iv) having a crystalline polypropylene content with a melting point (Tm) from DSC analysis according ISO 11357 in the range of 160 to 170° C., and

(v) optionally a crystalline polyethylene content with a melting point from DSC analysis according ISO 11357 in the range of 105 to 130° C.

6. The extruded tube according to claim 1 wherein the amount of heterophasic polypropylene copolymer is in an amount of 50 to 99 wt % of the heterophasic polypropylene composition.

7. The extruded tube according to claim 1 wherein the heterophasic polypropylene composition has a MFR 2 of 1.0 to 10.0 g/10 min, measured in accordance with ISO 1133 (230° C., 2.16 kg load).

8. The extruded tube according to claim 1 wherein the heterophasic polypropylene composition has an amount of 0.1 to 3.0 wt % of reinforcing filler.

9. The extruded tube according to claim 1 wherein the heterophasic polypropylene copolymer has a detectable crystalline polyethylene content which fulfils the equation Hm-PE/Hm-PP<5.

10. The extruded tube according to claim 1 wherein the heterophasic polypropylene copolymer is further characterized by an intrinsic viscosity, measured according to ISO 1628/1 in decalin at 135° C., of the XCS fraction, determined at 25° C. according to ISO 16152, in the range of 2 to 7.0 dl/g.

11. The extruded tube according to claim 1 wherein heterophasic polypropylene composition has a further stabilizer comprising at least one amine group.

12. The extruded tube according to claim 1 wherein the heterophasic polypropylene composition comprises one or more of a metal deactivator or UV stabilizer.

13. A buffertube comprising an extruded tube comprising a heterophasic polypropylene composition comprising:

(a) a heterophasic polypropylene copolymer, and

(b) an antioxidant comprising a sterically hindered phenol,

wherein the heterophasic polypropylene copolymer fulfills the following features:

(i) the relative amount of crystalline polypropylene in the heterophasic polypropylene copolymer is above 20 wt % and less than 45 wt %,

(ii) the relative amount of xylene cold solubles (XCS) fraction in said heterophasic polypropylene copolymer is at least 10 wt %,

(iii) the relative content of isolated ethylene sequences (I(E)) of the XCS fulfills the equation:

I ( E )<78−1.97× C+ 0.015×( C ) 2   (I)

wherein C is the comonomer content [wt %] of the XCS fraction and

wherein the I(E) content is defined by equation:

I

⁡

(

E

)

=

fPEP

(

fEEE

+

fPEE

+

fPEP

)

×

100

(

II

)

wherein

I(E) is the relative content of isolated to block ethylene sequences [in %];

fPEP is the mol fraction of propylene/ethylene/propylene sequences (PEP) in the sample;

fPEE is the mol fraction of propylene/ethylene/ethylene sequences (PEE) and of ethylene/ethylene/propylene sequences (EEP) in the sample;

fEEE is the mol fraction of ethylene/ethylene/ethylene sequences (EEE) in the sample wherein all sequence concentrations being based on a statistical triad analysis of 13 C-NMR data.

14. An optical fiber cable comprising at least one buffertube, wherein the buffertube comprises an extruded tube comprising a heterophasic polypropylene composition comprising:

(a) a heterophasic polypropylene copolymer, and

(b) an antioxidant comprising a sterically hindered phenol,

wherein the heterophasic polypropylene copolymer fulfills the following features:

(i) the relative amount of crystalline polypropylene in the heterophasic polypropylene copolymer is above 20 wt % and less than 45 wt %,

(ii) the relative amount of xylene cold solubles (XCS) fraction, determined at 25° C. according to ISO 16152, in said heterophasic polypropylene copolymer is at least 10 wt %,

(iii) the relative content of isolated ethylene sequences (I(E)) of the XCS fulfills the equation:

I ( E )<78−1.97× C+ 0.015×( C ) 2   (I)

wherein C is the comonomer content [wt %] of the XCS fraction and

wherein the I(E) content is defined by equation:

I

⁡

(

E

)

=

fPEP

(

fEEE

+

fPEE

+

fPEP

)

×

100

(

II

)

wherein

I(E) is the relative content of isolated to block ethylene sequences [in %];

fPEP is the mol fraction of propylene/ethylene/propylene sequences (PEP) in the sample;

fPEE is the mol fraction of propylene/ethylene/ethylene sequences (PEE) and of ethylene/ethylene/propylene sequences (EEP) in the sample;

fEEE is the mol fraction of ethylene/ethylene/ethylene sequences (EEE) in the sample wherein all sequence concentrations being based on a statistical triad analysis of 13 C-NMR data.

15. The extruded tube according to claim 8 , wherein the reinforcing filler comprises talc.