Thermoplastic blend formulations for cable insulations

Patent metadata

Field	Value
Publication number	US-2016194489-A1
Application number	US-201314911674-A
Country	US
Kind code	A1
Filing date	Aug 12, 2013
Priority date	Aug 12, 2013
Publication date	Jul 7, 2016
Grant date	—

Abstract

The present invention relates to a polymer composition suitable for the manufacture of an electrical insulation layer for cables having superior mechanical and electrical properties and being environmentally friendly, to a cable comprising said polymer composition as well as to the use of the polymer composition as an electrical insulation layer in cables.

First claim

1 . A polymer composition comprising:
a first copolymer being an ethylene-propylene copolymer comprising from 60 to 95% by weight propylene and from 5 to 40% by weight ethylene, based on the total weight of the first copolymer, and a copolymer blend comprising a second copolymer being a butylene-propylene copolymer, wherein the second copolymer comprises from 15 to 35% by weight 1-butylene and from 30 to 65% by weight propylene, based on the total weight of the second copolymer, wherein the weight ratio of the first copolymer to the copolymer blend ranges from 90:10 to 10:90, wherein the polymer composition has a softening temperature according to the Vicat method based on ASTM-D1525 of more than 120° C. and a Young's modulus determined according to ISO 527-2 of less than 500 MPa, and wherein the polymer composition has DC electrical breakdown strength at room temperature determined according to ASTM D149-87 of higher than 300 kV/mm.

2 . The polymer composition according to claim 1 , wherein the polymer composition shows no phase separation occurrence determined via visual inspection, polarized microscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM).

3 . The polymer composition according to claim 1 , wherein the second copolymer further comprises from 15 to 35% by weight ethylene, based on the total weight of the second copolymer.

4 . The polymer composition according to claim 1 , wherein the polymer composition has a steady state conductivity (DC) at 70° C. and 20 kV/mm on 1 mm thick plates after at least 80 hours of less than 1*10 −12 S/m, preferably of less than 2*10 −13 S/m, and more preferably of less than 2.5*10 −14 S/m.

5 . The polymer composition according to claim 1 , wherein the polymer composition exhibits a linear elasticity limit of higher than 6%, more preferably higher than 10%, most preferably higher than 12%, determined according to ISO 527-2.

6 . The polymer composition according to claim 1 , wherein the polymer composition exhibits a dielectric constant at room temperature of less than 2.8, more preferably less than 2.5, most preferably less than 2.3 measured by ASTM D150, IEC 60250.

7 . The polymer composition according to claim 1 , wherein the polymer composition has a softening temperature according to the Vicat method based on ASTM-D1525 of more than 140° C.

8 . The polymer composition according to claim 1 , wherein the polymer composition has a Young's modulus determined according to ISO 527-2 of less than 400 MPa.

9 . The polymer composition according to claim 1 , wherein the first copolymer has an average ethylene block length of 1.0 to 1.5 monomer units.

10 . The polymer composition according to claim 1 , wherein the first copolymer has an average propylene block length of 5.0 to 10.0 monomer units.

11 . The polymer composition according to claim 1 , wherein the first copolymer has a proportion of ethylene-propylene-ethylene triades of 4% to 20% based on the total number of triades present in the first copolymer.

12 . The polymer composition according to claim 1 , wherein the first copolymer has a proportion of propylene-ethylene-propylene triades of 6% to 20% based on the total number of triades present in the first copolymer.

13 . The polymer composition according to claim 1 , wherein the first copolymer has an overall proportion ethylene-propylene-ethylene (EPE) and propylene-ethylene-propylene (PEP) units of 10 to 20% by weight on average, based on the total number of triades present in the first copolymer.

14 . The polymer composition according to claim 1 , wherein the first copolymer has a proportion of propylene-propylene diades of 60% to 79% based on the total number of diades present in the first copolymer.

15 . The polymer composition according to claim 1 , wherein the first copolymer has a proportion of ethylene-propylene diades of 16% to 30% based on the total number of diades present in the first copolymer.

16 . The polymer composition according to claim 1 , wherein the first copolymer has a proportion of ethylene-ethylene diades of 1% to 4.5% based on the total number of diades present in the first copolymer.

17 . The polymer composition according to claim 1 , wherein the first copolymer has a proportion of polypropylene-polypropylene-polypropylene triades of 50% to 70% based on the total number of triades present in the first copolymer.

18 . The polymer composition according to claim 1 , wherein the first copolymer has a proportion of propylene-propylene-ethylene triades of 12% to 25% based on the total number of triades present in the first copolymer.

19 . The polymer composition according to claim 1 , wherein the first copolymer has a proportion of ethylene-ethylene-ethylene triades of 0.1% to 2% based on the total number of triades present in the first copolymer.

20 . The polymer composition according to claim 1 , wherein the copolymer blend further comprises from 0.01 to 90% by weight of an isotactic propylene polymer (i-PP).

21 . The polymer composition according to claim 1 , wherein the polymer composition further contains one or more optional additives selected from filler material, wetting/dispersing agent, plasticizer, antioxidant, light absorber, further additive(s), preferably less than 25% by weight based on the total weight of the polymer composition.

22 . A method for producing a polymer composition, comprising the steps of
i) mixing
a first copolymer being an ethylene-propylene copolymer comprising from 60 to 95% by weight propylene and from 5 to 40% by weight ethylene, and
a copolymer blend comprising a second copolymer being a butylene-propylene copolymer, wherein
the second copolymer comprises from 15 to 35% by weight 1-butylene and from 30 to 65% by weight propylene, and
optionally further additives,
in a weight ratio of the first copolymer to the polymer blend ranging from 90:10 to 10:90, at an elevated temperature, preferably at about 190 to 230° C., and ii) cooling the mixture obtained from step i) at a cooling rate of lower than 10° C./min, preferably lower than 1° C./min.

23 . A cable for direct current (DC) or alternating current (AC) medium and/or high voltage power transmission or distribution comprising a conductor surrounded by an insulation layer of the polymer composition according to claim 1 .

24 . The cable according claim 23 , wherein at least one of the following features (a 1 ) to (a 3 ) is met:
(a 1 ) a conductive layer is located between the conductor and the inner surface of the insulation layer, (a 2 ) a semi-conductive layer is present in the cable, (a 3 ) a jacketing layer covers at least one of the conductive layer, insulation layer and/or semi-conductive layer.

25 . The cable according to claim 23 , wherein the insulation layer has a thickness of more than 10 mm.

26 . The cable according to claim 23 , wherein the semi-conductive layer (a 2 ) exhibits a conductivity of higher than 10 −8 S/m, preferably higher than 10 4 S/m at 25° C.

27 . (canceled)

28 . An insulating material for electrical articles comprising the polymer composition according to claim 1 .

29 . An electrical article comprising the polymer composition according to claim 1 .

30 . An electrical article comprising the cable according to claim 23 .

31 . A (semi-)

Assignees

• Abb Technology Ltd

Inventors

• Ho Chau-Hon
• Ghoul Cherif
• Dominguez Gustavo
• Jedenmalm Anneli
• Friberg Andreas
• Krivda Andrej
• Xie Lei
• Farkas Andreas

Classifications

• C08L2203/202

  use in electrical wires or wirecoating · CPC title

• C08L2205/03

  containing three or more polymers in a blend · CPC title

• H01B3/441

  from alkenes · CPC title

• C08L23/16

  Ethylene-propylene or ethylene-propylene-diene copolymers · CPC title

• C08L23/20 Primary

  having four to nine carbon atoms · CPC title