Polymer composition and a power cable comprising the polymer composition

Patent metadata

Field	Value
Publication number	US-10950366-B2
Application number	US-202016777348-A
Country	US
Kind code	B2
Filing date	Jan 30, 2020
Priority date	Nov 3, 2010
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

An alternating current (AC) power cable includes a conductor surrounded by at least an inner semiconductive layer including a first semiconductive composition, an insulation layer including a polymer composition, an outer semiconductive layer including a second semiconductive composition, and optionally a jacketing layer including a jacketing composition, in that order. The polymer composition of the insulation layer includes an unsaturated low density polyethylene (LDPE) copolymer of ethylene with one or more polyunsaturated comonomers and a crosslinking agent. The polymer composition of the insulation layer has a dielectric loss expressed as tan δ (50 Hz) of 12.0×10 −4 or less, when measured at 25 kV/mm and 130° C. according to “Test for Tan δ measurements on 10 kV cables”.

First claim

What is claimed is:

1. An alternating current (AC) power cable, comprising a conductor surrounded by at least an inner semiconductive layer comprising a first semiconductive composition, an insulation layer comprising a polymer composition, and an outer semiconductive layer comprising a second semiconductive composition, in that order, wherein the polymer composition of the insulation layer comprises a polyolefin and a crosslinking agent, wherein the polyolefin is an unsaturated LDPE copolymer and wherein the polymer composition of the insulation layer has a dielectric loss expressed as tan δ (50 Hz) of 12.0×10 −4 or less, when measured at 25 kV/mm and 130° C. according to “Test for Tan δ measurements on 10 kV cables” as described in the description part under “Determination methods”.

2. The cable according to claim 1 , wherein the polymer composition of the insulation layer has a dielectric loss expressed as tan δ (50 Hz) of 11.0×10 −4 or less, when measured at 25 kV/mm and 130° C. according to “Test for Tan δ measurements on 10 kV cables” as described in the description part under “Determination methods”.

3. The cable according claim 1 , wherein the polymer composition of the insulation layer has a dielectric loss expressed as tan δ (50 Hz) of 0.01-10.0×10 −4 , when measured at 25 kV/mm and 130° C. according to “Test for Tan δ measurements on 10 kV cables” as described in the description part under “Determination methods”.

4. The cable according to claim 1 , wherein the polyolefin is obtainable by a high pressure process comprising:
(a) compressing one or more monomer(s) under pressure in a compressor, using a compressor lubricant for lubrication,
(b) polymerising a monomer together with one or more comonomer(s) in a polymerisation zone,
(c) separating the obtained polyolefin from the unreacted products and recovering the separated polyolefin in a recovery zone,
wherein in said a) above, the compressor lubricant comprises a mineral oil.

5. The cable according to claim 4 , wherein the compressor lubricant comprises white oil as the mineral oil and is suitable for production of polymers for food or medical industry.

6. The cable according to claim 4 , wherein the mineral oil is a white mineral oil which meets the requirements given for white mineral oil in European Directive 2002/72/EC of 6 Aug. 2002, Annex V, for plastics used in food contact.

7. The cable according to claim 1 , wherein the crosslinking agent is peroxide.

8. The cable according to claim 1 , wherein the polyolefin is an unsaturated LDPE copolymer of ethylene with at least one polyunsaturated comonomer.

9. The cable according to claim 8 , wherein the polyunsaturated comonomer is a straight carbon chain having at least 8 carbon atoms and at least 4 carbons between non-conjugated double bonds, of which at least one is located at terminal of the straight carbon chain.

10. The cable according to claim 8 , wherein the polyunsaturated comonomer is a diene comprising at least eight carbon atoms, the first carbon-carbon double bond is located at terminal of the diene, and the second carbon-carbon double bond is non-conjugated to the first carbon-carbon double bond.

11. The cable according to claim 8 , wherein the polyunsaturated comonomer is a diene selected from the group consisting of 1,7-octadiene, 1,9-decadiene, 1,11-dodecadiene, 1,13-tetradecadiene, 7-methyl-1,6-octadiene, 9-methyl-1,8-decadiene, and mixtures thereof.

12. The cable according to claim 1 , wherein each of the inner and outer semiconductive composition comprises independently a conductive filler comprising a carbon black.

13. The cable according to claim 12 , wherein the carbon black has one or more of the following properties: i) a primary particle size of at least 5 nm which is defined as the number average particle diameter according to ASTM D3849-95a procedure D, ii) iodine absorption number (IAN) of at least 10 mg/g, when determined according to ASTM D-1510-07; and/or iii) DBP (dibutyl phthalate) absorption number (=oil number) of at least 30 cm 3 /100 g, when measured according to ASTM D 2414-06a.

14. The cable according to claim 1 , wherein the cable further comprises a jacketing layer comprising a jacketing composition.

15. The cable according to claim 14 , wherein the jacketing composition comprises a polyolefin (j) which is a polyolefin homopolymer or copolymer selected from a polypropylene (PP), polyethylene (PE), or any mixtures thereof.

16. The cable according to claim 1 , wherein at least the polymer composition of the insulation layer is crosslinked in the presence of said crosslinking agent.

17. The cable according to claim 1 , wherein at least the first semiconductive composition of the inner semiconductive layer and the polymer composition of the insulation layer are crosslinked.

18. The cable according to claim 1 , wherein the cable is a MV, HV or EHV AC power cable.

19. A process for producing an alternating current (AC) power cable according to claim 1 , wherein the process comprises:
applying on the conductor the inner semiconductive layer comprising the first semiconductive composition, the insulation layer comprising the polymer composition, and the outer semiconductive layer comprising the second semiconductive composition.

20. The process for producing an alternating current (AC) power cable according to claim 19 , wherein the process comprises crosslinking at least the polyolefin of the polymer composition of the insulation layer in the presence of the crosslinking agent and at crosslinking conditions.

21. The cable according claim 1 , wherein the polymer composition of the insulation layer has a dielectric loss expressed as tan δ (50 Hz) of 0.5-7.0×10 −4 , when measured at 25 kV/mm and 130° C. according to “Test for Tan δ measurements on 10 kV cables” as described in the description part under “Determination methods”.

Assignees

• Borealis Ag

Inventors

• Nilsson Ulf
• Smedberg Annika
• Campus Alfred

Classifications

• H01B7/00

  Insulated conductors or cables characterised by their form · CPC title

• H01B3/44 Primary

  vinyl resins; acrylic resins (silicones H01B3/46) · CPC title

• H01B9/00

  Power cables · CPC title

• C08K5/01

  Hydrocarbons {(C08K5/0091 takes precedence)} · CPC title

• C08K3/04 Primary

  Carbon · CPC title