Polymer composition and a power cable comprising the polymer composition

Patent metadata

Field	Value
Publication number	US-10453585-B2
Application number	US-201715451162-A
Country	US
Kind code	B2
Filing date	Mar 6, 2017
Priority date	Nov 11, 2009
Publication date	Oct 22, 2019
Grant date	Oct 22, 2019

Abstract

A crosslinkable and crosslinked polymer composition containing a low density polyethylene (LDPE) homopolymer or low density polyethylene (LDPE) copolymer has excellent direct current (DC) electrical properties. The crosslinked polymer composition has an electrical conductivity of 150 fS/m or less, when measured at 70° C. and a 30 kV/mm mean electric field from a non-degassed, 1 mm thick plaque sample of the crosslinked polymer composition when measured according to a direct current (DC) conductivity method. A cable can be surrounded by at least one layer of the polymer composition.

First claim

What is claimed is:

1. A crosslinked polymer composition comprising a polyolefin, wherein the crosslinked polymer composition has an electrical conductivity of 150 fS/m or less, when measured at 70° C. and 30 kV/mm mean electric field from a non-degassed, 1 mm thick plaque sample consisting of a crosslinked polymer composition according to direct current (DC) conductivity method (1) as described under “Determination methods”,
wherein the polyolefin is a low density polyethylene (LDPE) homopolymer or low density polyethylene (LDPE) copolymer.

2. The crosslinked polymer composition of claim 1 , wherein the polyolefin is obtained 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) polymerizing a monomer optionally together with one or more comonomer(s) in a polymerization zone,
(c) separating the obtained polyolefin from unreacted products, and recovering the separated polyolefin in a recovery zone,
wherein in step (a) the compressor lubricant comprises a mineral oil.

3. The crosslinked polymer composition of claim 2 , wherein the mineral oil is present at a maximum level of up to 0.4 wt % based on the amount of the polyolefin.

4. The crosslinked polymer composition of claim 3 , wherein the mineral oil is a white mineral oil which meets requirements given for white mineral oil in European Directive 2002/72/EC of 6 Aug. 2002, Annex V, for plastics used in food contact.

5. The crosslinked polymer composition of claim 1 , wherein the crosslinked polymer composition has an electrical conductivity of 140 fS/m or less, when measured at 70° C. and 30 kV/mm mean electric field from a non-degassed, 1 mm thick plaque sample consisting of a crosslinked polymer composition according to DC conductivity method (1) as described under “Determination methods”.

6. The crosslinked polymer composition of claim 1 , which has an electrical conductivity of 0.27 fS/m or less, when measured at 20° C. and 40 kV/mm mean electric field from a degassed, 0.5 mm thick plaque sample consisting of a crosslinked polymer composition according to DC conductivity method (2) as described under “Determination methods”.

7. The crosslinked polymer composition of claim 1 , further comprising an antioxidant(s) selected from the group consisting of sterically hindered phenols, aromatic amines, aliphatic sterically hindered amines, organic phosphites or phosphonites, thio compounds, and mixtures thereof.

8. The crosslinked polymer composition of claim 1 , further comprising a scorch retarder(s), wherein the scorch retarder is dimers of aromatic alpha-methyl alkenyl monomers.

9. The crosslinked polymer composition of claim 1 , wherein the polyolefin is a saturated LDPE homopolymer or a saturated LDPE copolymer of ethylene with one or more comonomer(s); or 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).

10. The crosslinked polymer composition of claim 1 , wherein the polyolefin 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 comprises a total amount of carbon-carbon double bonds/1000 carbon atoms of more than 0.4/1000 carbon atoms.

11. The crosslinked polymer composition of claim 10 , wherein the unsaturated LDPE copolymer is an unsaturated LDPE copolymer of ethylene with at least one polyunsaturated comonomer and optionally with one or more other comonomer(s).

12. The crosslinked polymer composition of claim 1 , wherein the polyolefin contains vinyl groups in total amount of more than 0.20/1000 carbon atoms.

13. A crosslinked power cable comprising a conductor which is 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 insulation layer comprises the crosslinked polymer composition as defined in claim 1 .

14. A process for producing a crosslinked power cable comprising a conductor surrounded by at least an inner semiconductive layer, an insulation layer, and an outer semiconductive layer, in that order, wherein the process comprises:
applying on the conductor the inner semiconductive layer comprising a first semiconductive composition, the insulation layer comprising a polymer composition and the outer semiconductive layer comprising a second semiconductive composition, wherein the insulation layer comprises a polymer composition which comprises a polyolefin which is an LDPE homopolymer or LDPE copolymer and a crosslinking agent, and
crosslinking at least the polyolefin of the polymer composition of the insulation layer in presence of a crosslinking agent and at crosslinking conditions so that the insulation layer comprises the crosslinked polymer composition as defined in claim 1 .

15. A process comprising:
(a) compressing one or more monomer(s) under pressure in a compressor, using a mineral oil compressor lubricant for lubrication,
(b) polymerizing a monomer optionally together with one or more comonomer(s) in a polymerization zone,
(c) separating the obtained polyolefin from unreacted products, and recovering the separated polyolefin in a recovery zone,
applying on a conductor 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, wherein the insulation layer comprises a polymer composition which comprises the polyolefin obtained in step (c) and a crosslinking agent, and
crosslinking at least the polyolefin of the polymer composition of the insulation layer in presence of a crosslinking agent and at crosslinking conditions so that the crosslinked polymer composition has an electrical conductivity of 150 fS/m or less, when measured at 70° C. and 30 kV/mm mean electric field from a non-degassed, 1 mm thick plaque sample consisting of a crosslinked polymer composition according to DC conductivity method (1) as described under “Determination methods”.

16. A polymer composition which is crosslinkable, wherein the polymer composition comprises a polyolefin and a crosslinking agent, and wherein the polymer composition has an electrical conductivity of 150 fS/m or less, when measured at 70° C. and 30 kV/mm mean electric field from a non-degassed, 1 mm thick plaque sample consisting of a crosslinked polymer composition according to DC conductivity method (1) as described under “Determination methods”.

17. The crosslinked polymer composition of claim 1 , wherein the crosslinked polymer composition has an electrical conductivity of 100 fS/m or less, when measured at 70° C. and 30 kV/mm mean electric field from the non-degassed, 1 mm thick plaque sample consisting of the crosslinked polymer composition according to the direct current (DC) conductivity method (1) as described under “Determination methods”.

18. The crosslinked polymer composition of claim 1 , wherein the crosslinked polymer composition has an electrical conductivity between 0.5 and 75 fS/m, when measured at 70° C. and 30 kV/mm mean electric field from the non-degassed, 1 mm thick plaque sample consisting of the crosslinked polymer composition according to the direct current (DC) conductivity method (1) as described under “Determination methods”.

Assignees

• Borealis Ag

Inventors

• Nilsson Ulf
• Smedberg Annika
• Campus Alfred

Classifications

• C10M101/02

  Petroleum fractions · CPC title

• C08F10/02

  Ethene · CPC title

• C08F210/02

  Ethene · CPC title

• H01B7/295

  using material resistant to flame · CPC title

• C08F110/02

  Ethene · CPC title