Crosslinked polymer composition for cable accessories
A crosslinked polymer composition based on a plastomer, which is suitable for producing at least one layer of cable accessories like cable joints, bushings or terminations; its use for preparing such a layer and the cable accessory comprising the composition.
1. A crosslinked polymer composition comprising:
a plastomer, wherein the plastomer is a copolymer of ethylene and a C 4 to C 8 alpha olefin comonomer and wherein the plastomer has a density (according to ISO 1183) in the range of 855 kg/m 3 to 890 kg/m 3 ,
wherein the crosslinked polymer composition has:
a Shore A value measured according to ISO 868 of equal to or below 80,
an elongation at break measured according to ISO 527-2 of at least 300%, and
wherein polymers other than the plastomer are absent.
2. The crosslinked polymer composition according to claim 1 , wherein the crosslinked polymer composition has a compression set value, measured according to DIN ISO 815 B (150° C., 24 h), of below 25%.
3. The crosslinked polymer composition according to claim 1 , wherein the crosslinked polymer composition has a hot set elongation, measured according to EN60811-2-1 after 15 min at 200° C. and a load of 20 N/mm 2 , of less than 100%.
4. The crosslinked polymer composition according to claim 1 , wherein the plastomer has
(i) a comonomer content in the range of 20.0 wt % to 45.0 wt %,
(ii) a melt flow rate (ISO 1133, 2.16 kg and 190° C.) in the range of 0.1 g/10 min up to 50.0 g/10 min,
(iii) a melting point (DSC, ISO 11357-1) below 100° C., and
(iv) a molecular weight distribution Mw/Mn in the range of 2.0 to 4.0.
5. The crosslinked polymer composition according to claim 4 , wherein the plastomer is produced in a high temperature solution polymerization process at a temperature higher than 100° C. in the presence of a metallocene catalyst.
6. The crosslinked polymer composition according to claim 1 , wherein the crosslinked polymer composition has been prepared by crosslinking the plastomer via peroxide crosslinking.
7. The crosslinked polymer composition according to claim 6 , wherein the crosslinked plastomer has been prepared via peroxide crosslinking with 0.1 to 2.0 wt % of a peroxide, wherein the peroxide is liquid at ambient temperature.
8. The crosslinked polymer composition of claim 1 , further comprising a conductive filler.
9. The crosslinked polymer composition according to claim 8 , wherein the conductive filler is selected from the group consisting of acetylene carbon black, furnace carbon black, and mixtures thereof, and wherein the conductive filler is added to the plastomer in an amount of 20.0 to 45.0 wt % based on the crosslinked polymer composition before crosslinking the plastomer.
10. The crosslinked polymer composition according to claim 9 , further comprising a non-linear conductive filler, selected from the group consisting of silicon carbide (SiC), doped or undoped zinc oxide (ZnO) SnO 2 , TiO 2 , and conductive polymers.
11. A method of use of the crosslinked polymer composition according to claim 1 for preparing an insulation layer and/or a semi-conductive layer of a cable accessory.
12. The method according to claim 11 , where in the cable accessory is a pre-molded cable joint.
13. An insulation layer and/or a semi-conductive layer of a cable accessory comprising the crosslinked polymer composition according to claim 1 .
14. An insulation layer of a pre-molded cable joint comprising the crosslinked polymer composition according to claim 1 .
15. A pre-molded cable joint comprising at least one insulation layer, the at least one insulation layer made from the crosslinked polymer composition according to claim 1 .