Polymer composition for W and C application with advantageous electrical properties

Patent metadata

Field	Value
Publication number	US-10626265-B2
Application number	US-201916267599-A
Country	US
Kind code	B2
Filing date	Feb 5, 2019
Priority date	Mar 17, 2010
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

The invention relates to a polymer composition with improved DC electrical properties, to the use of the composition for producing a cable layer and to a cable surrounded by at least one layer comprising the polymer composition.

First claim

The invention claimed is:

1. A direct current (DC) power cable comprising a conductor which is surrounded at least by an inner semiconductive layer, an insulation layer and an outer semiconductive layer, in that order, wherein at least the insulation layer comprises a crosslinked polymer composition comprising:
(a) from 0.1 to 40 wt % of a polyethylene selected from the group consisting of: very low density polyethylene (VLDPE) having a density of from 850 to 909 kg/m 3 , linear low density polyethylene (LLDPE) having a density of from 909 to 930 kg/m 3 , medium density polyethylene (MDPE) having a density of from 930 to 945 kg/m 3 , and high density polyethylene (HDPE) having a density of 945 kg/m 3 or more; and
(b) from 60 to 99.9 wt % of a low density polyethylene (LDPE);
wherein the crosslinked polymer composition has an electrical conductivity of from 0.01 to 20.0 fS/m, when measured according to DC conductivity method (1) using a 1 mm thick plaque sample as described under “Determination Methods.”

2. The cable according to claim 1 , wherein the crosslinked polymer composition has an electrical conductivity of from 0.05 to 10.0 fS/m, when measured according to DC conductivity method (1) using a 1 mm thick plaque sample as described under “Determination Methods”.

3. The cable according to claim 1 , wherein the amount of the polyethylene (a) is from 1.0 to 30 wt % based on the combined weight of the polyethylene (a) and the LDPE (b).

4. The cable according to claim 1 , wherein the amount of the LDPE (b) is from 70 to 99.0 wt % based on the combined weight of the polyethylene (a) and the LDPE (b).

5. The cable according to claim 1 , wherein the polyethylene (a) is selected from very low density polyethylene (VLDPE) copolymers, linear low density polyethylene (LLDPE) copolymers, medium density polyethylene (MDPE) copolymers, or high density polyethylene (HDPE) homopolymers or copolymers.

6. The cable according to claim 1 , wherein the crosslinked polymer composition has a weight fraction of crystals with lamella thickness >10 nm of at least 0.5 wt %, when measured according to DSC method as described in the description part under “Determination Methods”.

7. The cable according to claim 1 , wherein the LDPE (b) is a saturated or unsaturated LDPE homopolymer or a saturated or unsaturated LDPE copolymer of ethylene with one or more comonomer(s).

8. The cable according to claim 1 , wherein the LDPE (b) is an unsaturated LDPE polymer, which is selected from an unsaturated LDPE homopolymer or an unsaturated LDPE copolymer of ethylene with one or more comonomer(s), and wherein the LDPE (b) comprises a total amount of carbon-carbon double bonds/1000 carbon atoms of more than 0.4/1000 carbon atoms.

9. The cable according to claim 1 , wherein the LDPE (b) is an unsaturated LDPE copolymer of ethylene with at least one polyunsaturated comonomer.

10. The cable according to claim 1 , wherein prior to crosslinking the crosslinked polymer composition comprises a polymer composition comprising a peroxide in an amount of from 0.1 to 110 mmol —O—O—/kg polymer composition.

11. The cable according to claim 1 , wherein the inner semiconductive layer comprises a crosslinked first semiconductive composition, the insulation layer comprises a polymer composition, consisting of the crosslinked polymer composition, and the outer semicoductive layer comprises a crosslinked second semiconductive composition.

12. A process for producing the DC power cable of claim 1 , which is preferably crosslinkable, wherein the process comprising the steps of:
applying on the conductor at least the inner semiconductive layer comprising a first semiconductive composition, the insulation layer comprising an insulation composition, and the outer semiconductive layer comprising a second semiconductive composition, in that order,
wherein the insulation composition comprises a polymer composition and a peroxide in an amount of from 0.1 to 110 mmol —O—O—/kg polymer composition, and wherein the polymer composition comprises:
(a) from 0.1 to 40 wt % of a polyethylene selected from the group consisting of: very low density polyethylene (VLDPE) having a density of from 850 to 909 kg/m 3 , linear low density polyethylene (LLDPE) having a density of from 909 to 930 kg/m 3 , medium density polyethylene (MDPE) having a density of from 930 to 945 kg/m 3 , and high density polyethylene (HDPE) having a density of 945 kg/m 3 or more; and
(b) from 60 to 99.9 wt % of a low density polyethylene (LDPE);
crosslinking the polymer composition of said insulation layer, in the presence of the peroxide and at crosslinking conditions.

13. The cable according to claim 1 , wherein the polyethylene (a) is HDPE.

14. The cable according to claim 1 , wherein prior to crosslinking the crosslinked polymer composition comprises a polymer composition comprising a peroxide in an amount of from 1.0 to 40 mmol —O—O—/kg polymer composition.

15. The cable according to claim 1 , wherein the polyethylene (a) and the LDPE (b) are the only polymer components of the crosslinked polymer composition.

16. The process of claim 12 , the process further comprising crosslinking the first semiconductive composition of the inner semiconductive layer, the second semiconductive composition of the outer semiconductive layer, or a combination thereof in the presence of a crosslinking agent at crosslinking conditions.

Assignees

• Borealis Ag

Inventors

• Nilsson Ulf
• Hagstrand Per-Ola
• Englund Villgot
• Farkas Andreas
• Ritums Janis

Classifications

• H10P14/60

  of insulating materials · CPC title

• C08L23/26 Primary

  modified by chemical after-treatment (saponified copolymers C08L23/0861; unsaturated acid salts C08L23/0876) · CPC title

• H01B13/0026

  Apparatus for manufacturing conducting or semi-conducting layers, e.g. deposition of metal · CPC title

• H01B9/027

  composed of semi-conducting layers · CPC title

• C08L2312/00

  Crosslinking · CPC title