Pipe comprising super slow crack growth resistant polyethylene

1. A pipe or a supplementary pipe article comprising a polyethylene composition comprising a base resin which comprises

(A) a first ethylene homo- or copolymer fraction having an MFR 2 , measured according to ISO 1133 at 190° C. and a load of 2.16 kg, in the range of 300 to 600 g/10 min, and

(B) a second ethylene homo- or copolymer fraction,

wherein fraction (A) has a lower average molecular weight than fraction (B), wherein the base resin has

a density in the range of 0.945 to 0.949 g/cm 3 and

an MFR 5 , measured according to ISO 1133 at 190° C. and a load of 5 kg, in the range of 0.2 to 0.4 g/10 min and

a comonomer content of higher than 2.0 wt.-% and a SHI(2.7/210) in the range of 66 to 90 and

a FRR 21/5 in the range of 30 to 60.

2. A pipe or a supplementary pipe article according to claim 1 , wherein the base resin has an η 2.7 >220 kPa·s.

3. A pipe or a supplementary pipe article according to claim 1 , wherein the pipe or supplementary pipe article has a rapid crack propagation (RCP) resistance, measured according to ISO 13477:1997(E), of −7° C. or lower.

4. A pipe or a supplementary pipe article according to claim 1 , wherein a test specimen from the pipe has a time to failure of more than 5000 h in the PENT test according to ASTM F 1473 at a constant load of 2.8 MPa and a temperature of 80° C.

5. A pipe or a supplementary pipe article according to claim 1 , wherein a test specimen of the pipe or supplementary pipe article withstands at least 5000 hours in the notch test according to ISO 13479 (9.2 bar, 80° C.).

6. A pipe or a supplementary pipe article according to claim 1 , wherein the composition has a Charpy Impact Strength, measured according to ISO 179/1eA at 0° C., of more than 15 kJ/m 2 .

7. A pipe or a supplementary pipe article according to claim 1 , wherein the base resin has a density in the range of 0.946 g/cm 3 to 0.948 g/cm 3 .

8. A pipe or a supplementary pipe article according to claim 1 , wherein fraction (A) is an ethylene homopolymer.

9. A pipe or a supplementary pipe article according to claim 1 , wherein fraction (A) has an MFR2, measured according to ISO 1133 at 190° C. and a load of 2.16 kg, in the range of 350 to 550 g/10 min.

10. A pipe or a supplementary pipe article according to claim 1 , wherein fraction (B) is an ethylene copolymer comprising at least one alpha-olefin comonomer having at least 6 carbon atoms.

11. A pipe or a supplementary pipe article according to claim 1 , wherein the comonomer content of the base resin is in the range of from more than 2.0 wt.-% to 6.0 wt.-%.

12. A pipe or a supplementary pipe article according to claim 1 , wherein the weight ratio of fractions (A):(B) in the base resin is in the range of 40:60 to 60:40.

13. A pipe or supplementary pipe article according to claim 1 , wherein a test specimen from the pipe has a time to failure in the Full Notch Creep Test according to ISO 16770 of at least 2500 h and a stress level of 4 MPa/80° C.

14. A pipe or supplementary pipe article according to claim 1 , wherein the base resin has an η 747 of 450 kPas or higher.

15. A pipe or supplementary pipe article according to claim 1 , wherein the base resin has a SHI(2.7/210) in the range of 72 to 85 and a FRR 21/5 in the range of 37 to 45.

16. A pipe or supplementary pipe article according to claim 1 , wherein fraction (A) is a copolymer.

17. A pipe or a supplementary pipe article comprising a polyethylene composition comprising a base resin which comprises

(A) an ethylene homopolymer fraction having an MFR 2 , measured according to ISO 1133 at 190° C. and a load of 2.16 kg, in the range of 300 to 600 g/10 min, and

(B) an ethylene copolymer fraction,

wherein fraction (A) has a lower average molecular weight than fraction (B), and wherein the base resin has

a density in the range of 0.945 to 0.949 g/cm 3 ,

an MFR 5 , measured according to ISO 1133 at 190° C. and a load of 5 kg, in the range of 0.2 to 0.4 g/10 min,

a comonomer content of higher than 2.0 wt.-%,

an SHI(2.7/210) in the range of 66 to 90, and

a Charpy Impact Strength, measured according to ISO 179/1eA at 0° C., of more than 19 kJ/m 2 , and

a FRR 21/5 in the range of 30 to 60.

18. A method for producing a pipe or a supplementary pipe article, comprising: extruding or injection moulding a polyethylene composition comprising a base resin which comprises:

(A) a first ethylene homo- or copolymer fraction, and

(B) a second ethylene homo- or copolymer fraction, wherein fraction (A) has a lower average molecular weight than fraction (B), and the base resin has

a density in the range of 0.945 to 0.949 g/cm 3 and

an MFR 5 , measured according to ISO 1133 at 190° C. and a load of 5 kg, in the range of 0.2 to 0.4 g/10 min and

a comonomer content of higher than 2.0 wt.-% and

a SHI(2.7/210) in the range of 66 to 90 and

a FRR 21/5 in the range of 30 to 60.