Crosslinkable composition without antioxidant and beneficial methane formation with reduced crosslinking

1. A polymer composition comprising:

a polyethylene and a crosslinking agent,

wherein:

the polymer composition contains a total amount of vinyl groups which is B vinyl groups per 1000 carbon atoms, and B 1 <B, wherein B 1 is 0.88, when measured prior to crosslinking according to method ASTM D6248-98;

the crosslinking agent is present in an amount which is Z wt %, based on the total amount (100 wt %) of the polymer composition, and Z<Z 2 , wherein Z 2 is 0.30; and

the polyethylene is a low density polyethylene (LDPE) homopolymer or copolymer.

2. The polymer composition of claim 1 , wherein the polyethylene is unsaturated or saturated.

3. The polymer composition of claim 1 , wherein decomposition of the crosslinking agent, during crosslinking of the polymer composition, results in formation of less than 130 ppm of methane, when measured according to the method for GC-Analysis.

4. The polymer composition of claim 1 , wherein the polymer composition is crosslinked and has a hot set elongation, with a load of 5 N/cm 2 , which is less than 175%, when measured according to the method for hot set determination.

5. The polymer composition of claim 1 , wherein the polyethylene is an unsaturated LDPE polymer.

6. The polymer composition of claim 1 , wherein the polyethylene is a copolymer of:

a monomer,

at least one polyunsaturated comonomer, and

zero or one or more other comonomer(s), and

wherein said total amount of vinyl groups (B) present in the polymer composition include vinyl groups originating from said at least one polyunsaturated comonomer.

7. The polymer composition of claim 6 , wherein the polyunsaturated comonomer is a diene.

8. The polymer composition of claim 1 , wherein the polyethylene is a copolymer of a monomer with at least one polyunsaturated comonomer, wherein the polyunsaturated comonomer is a straight carbon chain with at least 8 carbon atoms, at least two non-conjugated double bonds of which at least one is terminal, and at least 4 carbon atoms between the non-conjugated double bonds.

9. The polymer composition of claim 8 , wherein the polyunsaturated comonomer is a C 8 to C 14 non-conjugated diene.

10. The polymer composition of claim 9 , wherein the polyunsaturated comonomer is selected from 1,7-octadiene, 1.9-decadiene, 1,11-dodecadiene, 1,13-tetradecadiene, or mixtures thereof.

11. The polymer composition of claim 1 , wherein the polyethylene is a copolymer of ethylene and 1,7-octadiene.

12. The polymer composition of claim 1 , wherein the polyethylene is a LDPE copolymer of ethylene with one or more polyunsaturated comonomer(s) and with zero or one or more other comonomer(s).

13. The polymer composition of claim 12 , wherein the polyethylene is a LDPE copolymer of ethylene with one or more polyunsaturated comonomer(s) and with zero or one or more other comonomer(s).

14. The polymer composition of claim 1 , wherein said polyethylene, before crosslinking, has:

a complex viscosity (η*) at 0.05 rad/sec, which is X Pas, and X 1 <X<X 2 , wherein X 1 is 10000 and X 2 is 30000, and

a complex viscosity (η*) at 300 rad/sec, which is Y Pas, and Y 1 <Y<Y 2 , wherein Y 1 is 5 and Y 2 is 350,

wherein both complex viscosities (η*) are determined according to method ISO 6721-1 on stabilized samples of the polyethylene.

15. The polymer composition of claim 1 , wherein:

B 1 is 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25 or 1.30, and/or

Z 2 is 0.28 or 0.26.

16. The polymer composition of claim 1 , wherein:

B<B 2 and B 2 is 3.0, and

Z 1 <Z<Z 2 , wherein Z 1 is 0.01.

17. The polymer composition of claim 1 , wherein the polyethylene contains a total amount of vinyl groups which is P vinyl groups per 1000 carbon atoms, wherein P 1 <P<P 2 and, P 1 is 0.89 and P 2 is 3.0.

18. The polymer composition of claim 17 , wherein P 1 is 0.90 and P 2 is 1.5.

19. The polymer composition of claim 17 , wherein the polymer composition simultaneously satisfies the following:

P 1 <P<P 2 wherein P 1 is 0.89 and P 2 is 3.0;

Z 1 <Z<Z 2 wherein Z 1 is 0.02 and Z 2 is 0.28; and

wherein the polyethylene has a melt flow rate MFR 2 which is A g/10 min and A 1 <A<A 2 wherein A 1 is 0.15 and A 2 is 3.0.

20. The polymer composition of claim 17 , wherein the polymer composition simultaneously satisfies the following:

P 1 <P<P 2 wherein P 1 is 0.9 and P 2 is 1.5;

Z 1 <Z<Z 2 wherein Z 1 is 0.05 and Z 2 is 0.20; and

wherein the polyethylene has a melt flow rate MFR 2 which is A g/10 min and A 1 <A<A 2 wherein A 1 is 0.60 and A 2 is 2.5.

21. The polymer composition of claim 1 , wherein the crosslinking agent comprises a peroxide.

22. An article comprising the polymer composition of claim 1 .

23. The article of claim 22 , wherein the layer(s) are insulating layer(s).

24. The article of claim 22 , wherein the article is a cable.

25. The article of claim 22 , wherein the article comprises layer(s) which is/are obtained from the polymer composition.

26. The article of claim 22 which is a power cable.

27. A process for producing the polymer composition of claim 1 , the process comprising blending the polyethylene with the crosslinking agent.

28. A process for producing the article of claim 22 , wherein the process comprises using the polymer composition to produce the article.

29. The process of claim 28 , wherein said article is a power cable and wherein said process comprises the steps of:

a 0 ) meltmixing the polymer composition, optionally together with further components; and

a) applying the meltmix obtained from step a 0 ) on a conductor to form at least one cable layer.

30. The process of claim 29 , wherein said article is a crosslinked power cable and wherein said process further comprises the step of: b) crosslinking the at least one cable layer obtained from step a).