Polymer composition comprising a polyolefin produced in a high pressure process, a high pressure process and an article

Patent metadata

Field	Value
Publication number	US-10246527-B2
Application number	US-201013509257-A
Country	US
Kind code	B2
Filing date	Nov 3, 2010
Priority date	Nov 11, 2009
Publication date	Apr 2, 2019
Grant date	Apr 2, 2019

Abstract

A power cable includes a conductor surrounded by one or more layers. At least one of the layers can include a polymer composition having an electric conductivity of 0.50×10 −15 S/m or less when measured according to DC conductivity method using a tape sample. The polymer composition can include a polyolefin which is obtainable by a high pressure polymerization process. This process includes: compressing one or more monomers under pressure in a compressor, in which a compressor lubricant, such as mineral oil is used for lubrication; polymerizing a monomer optionally together with one or more comonomers in a polymerization zone; and separating the obtained polyolefin from the unreacted products and recovering the separated polyolefin in a recovery zone.

First claim

What is claimed is:

1. A direct current (DC) 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 insulation layer comprises a polymer composition having an electric conductivity of 0.50×10 −15 S/m or less, when measured according to DC conductivity method using a tape sample consisting of the polymer composition as described under “Determination Methods”, the polymer composition comprising a polyolefin which is a low density polyethylene (LDPE) copolymer of ethylene with a polyunsaturated comonomer obtained by a high pressure polymerization process comprising:
(a) compressing ethylene with the polyunsaturated comonomer under pressure in a compressor, wherein a compressor lubricant is used for lubrication,
(b) polymerizing ethylene with the polyunsaturated comonomer in a polymerization zone,
(c) separating the obtained polyolefin from the unreacted products and recovering the separated polyolefin in a recovery zone,
wherein the compressor lubricant comprises a mineral oil.

2. The direct current (DC) power cable according to claim 1 , wherein the polymer composition has an electrical conductivity of 0.48×10 −15 S/m or less, when measured according to DC conductivity method using a tape sample consisting of the polymer composition, as described under “Determination Methods”.

3. The direct current (DC) power cable according to claim 1 , wherein the LDPE copolymer of ethylene is unsaturated.

4. The direct current (DC) power cable of claim 1 , wherein
in step a), the compressor lubricant comprises white oil as the mineral oil and is suitable for production of polymers for food or medical industry; and wherein
the polymerization step b) is operated at a pressure up to 4000 bar, and at a temperature of up to 400° C.

5. The direct current (DC) power cable of claim 1 , wherein the mineral oil has a viscosity of at least 8.5×10-6 m2/s at 100° C.

6. A process for producing the direct current (DC) power cable according to claim 1 , comprising;
applying at least the inner semiconductive layer, the insulation layer and the outer semiconductive layer on the conductor in that order wherein the insulation layer comprises the polymer composition; and optionally crosslinking at least the obtained layer of the power cable.

7. The direct current (DC) power cable of claim 1 , wherein the mineral oil is a white mineral oil.

8. The direct current (DC) power cable of claim 1 , wherein the mineral oil comprises 5% or less by weight of a hydrocarbon having less than 25 carbon atoms.

9. The direct current (DC) power cable of claim 1 , wherein the mineral oil comprises a hydrocarbon having an average molecular weight of 480 or more.

Assignees

• Nilsson Ulf
• Smedberg Annika
• Campus Alfred
• Blok Achim
• Voigt Bjorn
• Borealis Ag

Inventors

• Nilsson Ulf
• Smedberg Annika
• Campus Alfred
• Blok Achim
• Voigt Bjorn

Classifications

• C08F110/02

  Ethene · CPC title

• H01B3/441

  from alkenes · CPC title

• C08F210/16

  Copolymers of ethene with alpha-alkenes, e.g. EP rubbers · CPC title

• C08F10/00 Primary

  Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond · CPC title

• C08F6/00

  Post-polymerisation treatments (C08F8/00 takes precedence; of conjugated diene rubbers C08C) · CPC title