Process for the production of a multipolar cable, and multipolar cable produced therefrom

1. A manufacturing process of a multipolar cable comprising

a) assembling a plurality of cores to form an assembled element provided with a plurality of interstitial zones between said cores,

wherein each of said cores comprises at least one conductive element and at least one layer of electrical insulation in a position radially external to said at least one conductive element and;

b) depositing by co-extrusion:

an expandable polymeric material in a position radially external to said cores so as to fill said interstitial zones and form a filling layer of substantially circular transverse cross section, wherein said expandable polymeric material is expanded during said deposition, and at least one containment layer of polymeric material in a position radially external to said filling layer.

2. The process according to claim 1 , further comprising depositing by co-extrusion at least one further layer of expandable polymeric material in a position radially external to said containment layer.

3. The process according to claim 1 , wherein said assembling comprises helicoidally winding together said plurality of cores in accordance with a predetermined pitch.

4. A multipolar cable comprising a plurality of cores, each core comprising at least one conductive element and at least one layer of electrical insulation in a position radially external to said at least one conductive element, said cores being twisted together so as to form an assembled element providing with a plurality of interstitial zones between said cores, said interstitial zones being filled with an expanded polymeric material to form a filling layer, said expanded polymeric layer being co-extruded with at least one containment layer of a polymeric material located in a position radially external to said filling layer; wherein:

said cable further comprises at least one additional layer of expandable polymeric material in a position radially external to said containment layer; and

wherein said expandable polymeric material of said filling layer, said polymeric material of said containment layer, and said expandable polymeric material of said further layer located in a position radially external to said containment layer are independently chosen from:

a) ethylene copolymers with an ethylenically unsaturated ester in which the quantity of unsaturated ester is between 5% and 80% by weight;

b) elastomeric copolymers of ethylene with at least one C 3 -C 12 α-olefin, and optionally a diene, having the following composition: 35-90 mol % ethylene, 10-65 mol % α-olefin, and 0-10 mol % diene;

c) copolymers of ethylene with at least one C 4 -C 12 α-olefin, and optionally a diene, having a density between 0.86 and 0.90 g/cm 3 ; and

d) propylene modified with ethylene/C 3 -C 12 α-olefin copolymers, wherein the ratio by weight between polypropylene and the ethylene/C 3 -C 12 α-olefin copolymer is between 90/10 and 30/70.

5. The multipolar cable according to claim 4 , wherein the expansion degree of said filling layer is between 5% and 500%.

6. The multipolar cable according to claim 5 , wherein said expansion degree is between 10% and 200%.

7. The multipolar cable according to claim 6 , wherein said expansion degree is between 20% and 150%.

8. The multipolar cable according to claim 4 , wherein the expansion degree of said at least one additional layer is between 5% and 500%.

9. The multipolar cable according to claim 8 , wherein said expansion degree of said least one additional layer is between 10% and 200%.

10. The multipolar cable according to claim 9 , wherein said expansion degree of said least one additional layer is between 20% and 150%.

11. The multipolar cable according to claim 4 , wherein the thickness of said containment layer is between 0.1 and 1.5 mm.

12. The multipolar cable according to claim 11 , wherein said thickness is between 0.2 and 1.0 mm.

13. The multipolar cable according to claim 12 , wherein said thickness is between 0.5 and 0.7 mm.