 Granular powder of modified polytetrafluoroethylene |
| What is claimed is: 1. A modified polytetrafluoroethylene granular powder obtained by granulating a ... |
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| Process for cross-linking or degrading polymers and shaped articles obtained by this process |
| What is claimed is: 1. A process for cross-linking (co)polymers of ethylene and elastomers, ... |
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| Block copolymers of monovinylarenes and conjugated dienes and preparation thereof |
| OF THE INVENTION This is a continuation-in-part of application Ser. No. 08/130,039 filed Sep. 30, 1... |
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| Plastic toughened plastics |
| In certain embodiments of our invention, plastic toughened plastics including an iPP and an mPE ... |
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| Method for producing aqueous polymer dispersions containing colorants |
| We claim: 1. A process for preparing dye-comprising aqueous polymer dispersions by aqueous emulsion ... |
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| Low temperature crosslinkable latexes formed by in-situ generation of a crosslinkable functionality |
| What is claimed is: 1. A crosslinkable latex composition comprising a crosslinkable polymer formed ... |
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| Clear barrier composites containing polyisobutylene/polyolefin alloy components |
| This invention relates to a composite film suitable for use in parenteral drug or blood container ... |
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| Matte finish biaxially oriented polypropylene film for cold seal release applications |
| The present invention is based upon the discovery of a new packaging film formulation which ... |
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| Photocurable sheet, moldings thereof, and processes for producing the same |
| What is claimed is: 1. A photocuring sheet wherein a photocuring resin composition (A) comprising ... |
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| Olefin resin composition |
| What is claimed is: 1. An olefinic resin composition which comprises: (A) 100 parts by weight of a ... |
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Water tree resistant insulating composition
| Details |
Inventors: Peruzzotti, Franco; Castellani, Luca; Dacal, Luis Jose; Garcia, Valeria;
Assignee: Pirelli Cavi S.p.A. (Milan, IT)
Primary Examiner: Reddick; Judy M.
Assistant Examiner:
Attorney, Agent or Firm: Finnegan, Henderson, Farabow, Garrett & Dunner, L.L.P.
The present invention is an improved electric insulation composition of a polymer and an additive that reduces water treeing due to electrical aging in water. The polymer additive is a hydrophobic/hydrophilic material with good compatibility with the polymer. The present invention is also a method of preventing electrical breakdown due to the formation of water trees by forming electrical cables with the insulation containing the disclosed anti-treeing additive. |
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DETAILED DESCRIPTION In the FIGURE an insulated electrical cable 1 includes a conductor 2; an internal sublayer 3; an electrically insulating layer 4; and an external sublayer 5; a metallic screen 6; and an outer sheath or jacket 7.
The conductor 2, as known in the art, is preferably made of stranded metal wires.
The internal and external sublayers 3 and 5 are preferably made of suitable compounds according to the prior art, extruded onto the conductor 2 separately from or simultaneously with the insulating layer 4.
The insulating layer 4 is preferably formed with the composition according to the present invention, described in detail below.
The internal sublayer 3, usually called in the art "conductor shield" is an electrically semiconducting layer for causing the electric field to be uniform around the conductor.
Methods and materials for making the shield layer will be readily apparent to the skilled artisan.
In a cable according to the present invention the internal sublayer 3 is preferably made of a compound based on cross-linked polyethylenealkilacrylate, charged with carbon-black, to render it semiconducting (i.
e.
with a resistivity <5 ohm/m at room temperature).
The external sublayer 5, usually called in the art "insulation shield" is a semiconductive layer, methods and materials for making this layer will be readily apparent to the skilled artisan.
In a cable according to a prefered embodiment of the present invention the external sublayer 5 is made from a compound based on EVA (ethylenevinylacetate), charged with carbon-black to make semiconducting.
Such layer, as is well known to the skilled in the art, has the object of circumscribing the electrical field round the conductor.
Externally to the outer semiconductive layer 5 there is a metallic screen 6, made of electrically conducting wires or tapes, helically wound, and a sheath or jacket 7 in polyvinylchloride (PVC) or thermoplastic polyethylene (PE).
In an example, a medium voltage cable, defined as 1/0 AWG (American Wire Gauge), 175 mils (4
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Adhesives and Rubbers 
