Continuous extruder process for manufacturing rheology-modified polyolefin for cable insulation layer

Abstract

Rheology-modified, additive-containing ethylenic polymer compositions are prepared in a continuously operated extruder comprising first, second and third zones by a process comprising the steps of:mixing in the second zone of the extruder an ethylenic polymer and a high-temperature decomposing peroxide at a temperature such that the half-life of the peroxide is equal to or greater than (≥) one minute and for a sufficient period of time to modify the rheology of the ethylenic polymer to produce a rheology-modified, melted ethylenic polymer for transfer to the third zone of the extruder; andadding to the third zone one or more additives to the rheology-modified, melted ethylenic polymer to produce the rheology-modified, additive-containing ethylenic polymer.

1 - 13 . (canceled) 
     
     
         14 . A crosslinked ethylenic polymer prepared by a process comprising
 a one-unit operation, continuous extrusion process for making a rheology-modified, additive-containing ethylenic polymer in a continuously operated multi-zone extruder sequentially comprising a first zone configured with a main feeder for adding a polymer into the extruder and optionally configured with an injector for adding a high-temperature decomposing peroxide into the first zone of the extruder, a second zone optionally configured with an injector for adding a high-temperature decomposing peroxide into the second zone of the extruder, a third zone configured with a side feeder for adding one or more additives into the third zone of the extruder, and an outlet for discharging material from the extruder, wherein the first zone is in material communication with the second zone via 0, 1 or more intermediary zones disposed therebetween, wherein the second zone is in material communication with the third zone via 0, 1 or more intermediary zones disposed therebetween, and wherein the third zone is in material communication with the outlet via 0, 1 or more intermediary zones disposed therebetween, and wherein at least one of the first and second zones is configured with the injector, the process comprising the steps of:   mixing in the second zone of the extruder an ethylenic polymer and a high-temperature decomposing peroxide at a temperature such that the half-life of the peroxide is equal to or greater than (≥) one minute and for a sufficient period of time to melt the ethylenic polymer and to modify the rheology of the melted ethylenic polymer to produce a rheology-modified, melted ethylenic polymer that is transferred to the third zone of the extruder; and   adding via the side feeder of the third zone one or more additives to the rheology-modified, melted ethylenic polymer to produce the rheology-modified, additive-containing ethylenic polymer; and   curing an extruded form of the blend to give a crosslinked ethylenic polymer.   
     
     
         15 . An insulation layer for a medium, high or extra-voltage power cable comprising a conductive core at least partially surrounded by the insulation layer, which comprises the the crosslinked ethylenic polymer of  claim 14 . 
     
     
         16 . A cable comprising a conductive core at least partially surrounded by the insulation layer of  claim 15 . 
     
     
         17 . A method of conducting electricity, the method comprising applying a voltage across the conductive core of the cable of  claim 16 , thereby causing electricity to flow through the conductive core. 
     
     
         18 . The crosslinked ethylenic polymer of  claim 14  wherein the crosslinked ethylenic polymer has a gel content greater than or equal to 40. 
     
     
         19 . The crosslinked ethylenic polymer of  claim 18  wherein the crosslinked ethylenic polymer has a white color. 
     
     
         20 . The crosslinked ethylenic polymer of  claim 19  comprising a water tree retardant. 
     
     
         21 . The crosslinked ethylenic polymer of  claim 20  wherein the water tree retardant is a poly(ethylene glycol). 
     
     
         22 . The crosslinked ethylenic polymer of  claim 21  wherein the crosslinked ethylenic polymer comprises an antioxidant. 
     
     
         23 . The crosslinked ethylenic polymer of  claim 22  wherein the crosslinked ethylenic polymer comprises a first ethylene-based polymer and a second ethylene-based polymer different than the first ethylene-based polymer. 
     
     
         24 . The crosslinked ethylenic polymer of  claim 22  comprising a clay.