Polymer composition and cable with advantageous electrical properties

Patent metadata

Field	Value
Publication number	US-11359080-B2
Application number	US-202017087390-A
Country	US
Kind code	B2
Filing date	Nov 2, 2020
Priority date	Oct 27, 2014
Publication date	Jun 14, 2022
Grant date	Jun 14, 2022

Abstract

The invention relates to polymer composition comprising a polyolefin (a) and an inorganic filler (b) wherein the polyolefin (a) is obtainable by a high pressure process which process comprises the steps: (i) compressing one or more monomer(s) under pressure in a compressor, using a compressor lubricant for lubrication, (ii) polymerising a monomer optionally together with one or more comonomer(s) in a polymerisation zone, (iii) separating the obtained polyolefin (a) from the unreacted products and recovering the separated polyolefin (a) in a recovery zone, wherein in step (i) the compressor lubricant comprises a non-mineral oil, power cable, for example a direct current (DC) power cable, use of a polymer composition and a process for producing a DC power cable.

First claim

The invention claimed is:

1. A polymer composition comprising a polyolefin (a), a peroxide and an inorganic filler (b) wherein the polyolefin (a) is obtainable by a high-pressure process which process comprises the steps:
(i) compressing one or more monomer(s) under pressure in a compressor, using a compressor lubricant for lubrication,
(ii) polymerising a monomer optionally together with one or more comonomer(s) in a polymerisation zone,
(iii) separating the obtained polyolefin (a) from the unreacted products and recovering the separated polyolefin (a) in a recovery zone, wherein in step (i) the compressor lubricant comprises a non-mineral oil; and
wherein the polyolefin (a) 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 C═C bonds in total amount of 0.2/1000 carbon atoms;
wherein the amount of the inorganic filler (b) is 0.1 to 5.0 wt % based on the combined amount of the polyolefin (a) and the inorganic filler (b);
wherein the polyolefin (a) comprises 10 to 250 ppm of the non-mineral oil; and wherein the polymer composition comprises peroxide in an amount of 5.0 to less than 40 mmol —O—O—/kg of the polymer composition.

2. A polymer composition according to claim 1 , wherein the non-mineral oil is polyalkylene glycol (PAG).

3. A polymer composition according to claim 1 , wherein the polymer composition has an electrical conductivity of 140 fS/m or less, for example, of 135 fS/m or less, for example, of 130 fS/m or less, for example, of 125 fS/m or less, for example, of 120 fS/m or less, for example, of 115 fS/m or less, for example, of from 0.01 to 110 fS/m or less, for example, of from 0.05 to 105 fS/m or less, when measured according to DC conductivity method using a 1 mm thick plaque sample as described under “Determination Methods.

4. A polymer composition according to claim 1 wherein the amount of polyolefin (a) in the polymer composition of the invention is at least 35 wt %, for example, at least 40 wt %, e.g. at least 50 wt %, for example, at least 75 wt %, e.g. 80 to 100 wt % or, for example, 85 to 100 wt %, of the total weight of the polymer component(s) present in the polymer composition, e.g. the amount of the polyolefin (a) is 70 wt % or, for example, 80 wt % or, e.g. 85 to 99.95 wt %, for example, 90.0 to 99.9 wt %, e.g. 95.0 to 99.9 wt %, for example, 96.0 to 99.9 wt %, based on the combined amount of the polyolefin (a) and the inorganic filler (b).

5. A polymer composition according to claim 1 , wherein the amount of the inorganic filler (b) is 0.1 to 4.0 wt %, based on the combined amount of the polyolefin (a) and the inorganic filler (b).

6. A polymer composition according to claim 1 , wherein the polyolefin (a) is a polyethylene, for example a polyethylene selected from a polyethylene polymerised in the presence of an olefin polymerisation catalyst and selected from an ethylene homopolymer or a copolymer of ethylene with one or more comonomer(s); or a polyethylene polymerised in a high pressure polymerisation process and, for example in the presence of an initiator(s), e.g. a low density polyethylene (LDPE) polymer polymerised in a high pressure polymerisation process and in the presence of an intiator(s), for example an LDPE selected from an optionally unsaturated LDPE homopolymer or an optionally unsaturated LDPE copolymer of ethylene with one or more comonomer(s), e.g. an LDPE selected from an optionally unsaturated LDPE homopolymer or an optionally unsaturated LDPE copolymer of ethylene with one or more comonomer(s).

7. A polymer composition according to claim 1 wherein the polyolefin(a) is an unsaturated LDPE copolymer of ethylene with at least one polyunsaturated comonomer and optionally with one or more other comonomer(s), the polyunsaturated comonomer consists, for example, of a straight carbon chain with at least 8 carbon atoms and at least 4 carbons between the non-conjugated double bonds, of which at least one is terminal, e.g., said polyunsaturated comonomer is a diene, for example a diene which comprises at least eight carbon atoms, the first carbon-carbon double bond being terminal and the second carbon-carbon double bond being non-conjugated to the first one, for example, a diene which is selected from C8- to C14-non-conjugated diene or mixtures thereof, e.g. selected from 1,7-octadiene, 1,9-decadiene, 1,11-dodecadiene, 1,13-tetradecadiene, 7-methyl-1,6-octadiene, 9-methyl-1,8-decadiene, or mixtures thereof, for example, from 1,7-octadiene, 1,9-decadiene, 1,11-dodecadiene, 1,13-tetradecadiene, or any mixture thereof.

8. A polymer composition according to claim 1 , wherein the inorganic filler (b) is selected from inorganic oxides, hydroxides, carbonates, nitrides, carbides, kaolin clay, talc, borates, alumina, titania or titanates, silica, silicates, zirconia, glass fibers, glass particles, or any mixtures thereof.

9. A polymer composition according to claim 1 wherein the inorganic filler (b) is selected from inorganic oxides, nitrides, carbides, kaolin clay, talc, borates, alumina, titania or titanates, silica, silicates, zirconia, glass fibers, glass particles, or any mixtures thereof, the inorganic filler (b) is, for example an inorganic oxide, e.g. an inorganic oxide selected from SiO2, MgO, TiO2 or ZnO, or any mixtures thereof, for example from SiO2, TiO2 or MgO, or any mixtures thereof.

10. A polymer composition according to claim 1 , wherein the polymer composition comprises crosslinking agent in an amount of 5.0 to less than 37 mmol —O—O—/kg polymer composition, e.g. less than 35 mmol —O—O—/kg polymer composition, for example of 0.1 to 34 mmol —O—O—/kg polymer composition, e.g. of 0.5 to 33 mmol —O—O—/kg polymer composition, for example from 5.0 to 30 mmol —O—O—/kg polymer composition, e.g. from 7.0 to 30 mmol —O—O—/kg polymer composition, for example from 10.0 to 30 mmol —O—O—/kg polymer composition.

11. A power cable, for example 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 one layer, for example at least the insulation layer, comprises a polymer composition according to claim 1 .

12. A process for producing a DC power cable, wherein the process comprises the steps of applying on a conductor, for example, by (co)extrusion, an inner semiconductive layer comprising a first semiconductive composition, an insulation layer comprising an insulation composition and an outer semiconductive layer comprising a second semiconductive composition, in that order, wherein the insulation composition of the insulation layer comprises a polymer composition according to claim 1 .

13. A polymer composition according to claim 1 , wherein the inorganic filler (b) is MgO.

Assignees

• Borealis Ag

Inventors

• Englund Villgot
• Hagstrand Per-Ola
• Smedberg Annika
• Nilsson Ulf

Classifications

• C08K3/013

  Fillers, pigments or reinforcing additives · CPC title

• C08L2203/202

  use in electrical wires or wirecoating · CPC title

• C08F2/38

  Polymerisation using regulators, e.g. chain terminating agents {, e.g. telomerisation} · CPC title

• C08L23/0815

  with aliphatic 1-olefins containing one carbon-to-carbon double bond · CPC title

• C08L71/02

  Polyalkylene oxides · CPC title