Polymer composition for w&c application with advantageous electrical properties

Abstract

The invention relates to a use of a polymer composition with improved DC electrical properties in a power cable layer and to a cable surrounded by at least one layer comprising the polymer composition.

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 at least one layer comprises a polymer composition comprising:
 (a) a polyolefin selected from the group consisting of a propylene homopolymer, a random copolymer of propylene with one or more comonomer(s), and a heterophasic copolymer of propylene with one or more comonomer(s), and   (b) optionally a second polyolefin which is different from the polyolefin (a).   
     
     
         2 . The direct current (DC) power cable according to  claim 1 , wherein the inner semiconductive layer comprises a first semiconductive composition, the insulation layer comprises the polymer composition, and the outer semiconductive layer comprises a second semiconductive composition. 
     
     
         3 . The direct current (DC) power cable according to  claim 1  wherein the outer semiconductive layer comprises the outer semiconductive layer comprises a non-crosslinked or crosslinked second semiconductive composition, and the inner semiconductive layer comprises a non-crosslinked first semiconductive composition. 
     
     
         4 . The direct current (DC) power cable according to  claim 1 , wherein the polymer composition has an electrical conductivity of 0.05 to 40 fS/m, when measured according to DC conductivity method as described under “Determination Methods”. 
     
     
         5 . The direct current (DC) power cable according to  claim 1 , wherein the amount of the polyolefin (a) is 95 to 100 wt % based on the combined weight of the polyolefin (a) and the optional second polyolefin (b). 
     
     
         6 . (canceled) 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . The direct current (DC) power cable according to  claim 1 , wherein the optional second polyolefin (b) is present and is an optionally unsaturated LDPE homopolymer or an optionally unsaturated LDPE copolymer of ethylene with one or more comonomer(s). 
     
     
         11 . The direct current (DC) power cable according to  claim 10 , wherein the polymer composition comprises no polyolefin (b). 
     
     
         12 . (canceled) 
     
     
         13 . The direct current (DC) power cable according to  claim 1 , wherein the polymer composition comprises a peroxide. 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . A process for producing the direct current (DC) power cable according to  claim 1 , wherein the process comprises the steps of
 applying on the conductor, the inner semiconductive layer comprising a first semiconductive composition, the insulation layer comprising an insulation composition, and the outer semiconductive layer comprising a second semiconductive composition, in that order, wherein at least one layer comprises the polymer composition,   and   optionally crosslinking one or more layers of the obtained cable in the presence of a crosslinking agent.   
     
     
         18 . The direct current (DC) power cable according to  claim 13 , wherein the polymer composition comprises up to 30 mmol —O—O—/kg polymer composition. 
     
     
         19 . The direct current (DC) power cable according to  claim 1 , wherein the layer comprising the polymer composition is not crosslinked. 
     
     
         20 . The direct current (DC) power cable according to  claim 1 , wherein the polyolefin (a) is a propylene homopolymer. 
     
     
         21 . The direct current (DC) power cable according to  claim 1 , wherein the polyolefin (a) is a random-heterophasic copolymer comprising a matrix phase and an elastomeric phase, the matrix phase comprising a propylene homopolymer or a propylene copolymer, and the elastomeric phase comprising a propylene copolymer.