High pressure radial polymerisation process for a copolymer of ethylene silane groups containing comonomer
A copolymer of ethylene with silane groups containing comonomer that is produced in a high pressure radical polymerization process comprising the steps of: (a) compressing ethylene together with the silane groups containing comonomer under pressure in a compressor, wherein a compressor lubricant is used for lubrication, (b) polymerizing ethylene together with the silane groups containing comonomer in a polymerization zone, (c) separating the obtained ethylene from the unreacted products and recovering the separated ethylene copolymer in a recovery zone, wherein in step a) the compressor lubricant comprises a mineral oil and ethylene copolymer has a silane groups containing comonomer content of 0.5 to 3 wt % and an MFR2 of 0.3 to 10 g/10 min. The co-polymer of ethylene with silane groups containing comonomer can be used.
1. A copolymer of ethylene with silane groups containing comonomer that is produced in a high pressure radical polymerisation process comprising the steps of:
(a) compressing ethylene together with the silane groups containing comonomer under pressure in a compressor, wherein a compressor lubricant is used for lubrication,
(b) polymerising ethylene together with the silane groups containing comonomer in a polymerisation zone,
(c) separating the obtained ethylene copolymer from the unreacted products and recovering the separated ethylene copolymer in a recovery zone,
wherein in step (a) the compressor lubricant comprises a mineral oil and the ethylene copolymer has a silane groups containing comonomer content of 0.5 to 3 wt % and an MFR2 of 0.3 to 10 g/10 min; and
wherein the copolymer has a hot set elongation percentage y satisfying:
y<−81.205x+193.16, wherein x represents wt % of the silane groups containing comonomer.
2. The copolymer of ethylene with silane groups containing comonomer according to claim 1 , wherein the MFR2 is from 0.5 to 2 g/10 min.
3. The copolymer of ethylene with silane groups containing comonomer according to claim 1 , wherein the silane groups containing comonomer content is less than 2 wt %.
4. The copolymer of ethylene with silane groups containing comonomer according to claim 1 , wherein the mineral oil is a petroleum product.
5. The copolymer of ethylene with silane groups containing comonomer according to claim 1 , wherein the mineral oil comprises paraffinic hydrocarbons.
6. The copolymer of ethylene with silane groups containing comonomer according to claim 1 , wherein the mineral oil does not comprise polyalkyleneglycol base components.
7. The copolymer of ethylene with silane groups containing comonomer according to claim 1 wherein the copolymer of ethylene with silane groups containing comonomer is crosslinked with a condensation reaction catalyst that is acidic.
8. The copolymer of ethylene with silane groups containing comonomer according to claim 7 , wherein the condensation reaction catalyst is a BrOnsted acid.
9. The copolymer of ethylene with silane groups containing comonomer according to claim 7 wherein the condensation reaction catalyst is a sulphonic acid.
10. The copolymer of ethylene with silane groups containing comonomer according to claim 9 , wherein the condensation reaction catalyst is an aromatic organic sulphonic acid.
11. The copolymer of ethylene with silane groups containing comonomer according to claim 1 , wherein the copolymer of ethylene with silane groups containing comonomer contains further polar comonomer(s) which are free from silane groups.
12. The copolymer of ethylene with silane groups containing comonomer according to claim 11 , wherein the polar comonomer(s) which are free from silane groups is vinyl acetate (EVA), methyl (meth)acrylate, (EMA & EMMA), ethyl acrylate (EEA), and/or butyl acrylate (EBA).
13. A cable comprising a conductor surrounded by one or more layers wherein at least one of said layer(s) comprises the copolymer of ethylene with silane groups containing comonomer according to claim 1 .
14. The cable according to claim 13 , wherein the cable is a low voltage power cable.
15. The cable according to claim 13 , wherein the at least one layer is an insulation layer.
16. The cable according to claim 15 , wherein the insulation layer is adjacent, and in direct contact.
17. The cable according to claim 15 , wherein the insulation layer is functioning as an insulation layer and jacketing layer.
18. A process for producing a copolymer of ethylene with silane groups containing comonomer according to claim 1 , wherein the ethylene copolymer with at least one silane groups containing comonomer that is produced in a high pressure radical process comprising the steps of:
(a) compressing ethylene together with the silane groups containing comonomer under pressure in a compressor, wherein a compressor lubricant is used for lubrication,
(b) polymerising ethylene together with the silane groups containing comonomer in a polymerisation zone,
(c) separating the obtained polyolefine from the unreacted products and recovering the separated polyolefine in a recovery zone,
wherein in step (a) the compressor lubricant comprises a mineral oil.
19. The process according claim 18 , wherein the polymerisation step Lb) is operated at a pressure up to 4000 bar and at a temperature of up to 400° C.
20. The process according to claim 18 , wherein the pressure is from 700 to 4000 bar and wherein the temperature is from 80 to 350° C.
21. The copolymer of ethylene with silane groups containing comonomer according to claim 2 , wherein the silane groups containing comonomer content is less than 2 wt %.
22. The cable according to claim 14 , wherein the at least one layer is an insulation layer.
23. The cable according to claim 16 , wherein the insulation layer is functioning as an insulation layer and jacketing layer.