Cable comprising a recyclable polymer layer

Abstract

An electrical cable has at least one elongate conductive element surrounded by a recyclable thermoplastic layer. The recyclable thermoplastic layer has at least a composite material (TPV) having a thermoplastic polymer matrix (a); and a vulcanized elastomer phase (b) dispersed within said thermoplastic matrix (a); and a polyethylene.

Claims

1. An electrical cable comprising: at least one elongate conductive element surrounded by a recyclable thermoplastic layer, the recyclable thermoplastic layer comprising at least: a composite material (TPV) comprising: (a) a thermoplastic polymer matrix; and (b) a vulcanized elastomer phase dispersed within said thermoplastic matrix (a); and a polyethylene.

2. The electrical cable according to claim 1, where the dispersed vulcanized elastomer phase (b) comprises a crosslinked ethylene-propylene-diene elastomer (EPDM).

3. The electrical cable according to claim 1, where the thermoplastic matrix (a) comprises a propylene homopolymer or copolymer.

4. The electrical cable according to claim 1, where the recyclable thermoplastic layer further comprises a copolymer of propylene and an alpha-olefin other than propylene.

5. The electrical cable according to claim 1, where the recyclable thermoplastic layer further comprises a dielectric liquid.

6. The electrical cable according to claim 1, where the recyclable thermoplastic layer further comprises benzophenone.

7. The electrical cable according to claim 1, where the cable is a low-voltage power cable.

8. The electrical cable according to claim 7, where the recyclable thermoplastic layer is an insulating layer.

9. The electrical cable according to claim 1, where the cable is a medium-voltage power cable.

10. The electrical cable according to claim 9, where the recyclable thermoplastic layer is an insulating layer or a semiconductive layer.

11. The electrical cable according to claim 4, where the recyclable thermoplastic layer further comprises a copolymer of propylene and ethylene.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The invention will be further illustrated by the FIGURE in the appendix and the illustrative example below.

[0054] FIG. 1 shows a schematic view of an electrical cable comprising an insulating thermoplastic layer of the invention.

[0055] For the sake of clarity, only the elements essential for the understanding of the invention have been represented schematically, and these are not to scale.

DETAILED DESCRIPTION

[0056] FIG. 1 shows an electrical cable 1, which comprises an elongate central electrically conductive element 2, in particular an element made of copper or aluminium. This electrical cable 1 further comprises a plurality of layers arranged successively and coaxially around this elongate central electrically conductive element 2, namely: a first semiconductive layer 3 referred to as the inner semiconductive layer, an electrically insulating layer 4, a second semiconductive layer 5 referred to as the outer semiconductive layer, a metal shield for earthing and/or protection 6, and an outer protective sheath 7.

[0057] The electrically insulating layer 4 is a recycled thermoplastic layer of the invention obtained by extrusion and comprising a TPV composite material; a polyethylene; advantageously a propylene copolymer (c); and optionally additives of the abovementioned type.

[0058] The semiconductive layers 3 and 5 are advantageously recycled extruded thermoplastic layers of the invention comprising a TPV composite material; a polyethylene; advantageously a propylene copolymer (c), optionally additives of the abovementioned type; and an electrically conductive filler (typically a carbon black).

[0059] The presence of the metal shield 6 and of the outer protective sheath 7 is preferred, but not essential, this cable structure being a structure of the customary type.

Example

[0060] The following compositions were tested, which include a composite material of the TPV type (commercial product of the Santoprene and OptiPren range based on an EPDM elastomer phase dispersed in a polypropylene matrix); a polyethylene (LLDPE BPD 3642), a propylene-ethylene copolymer (Moplen RP210G), a mineral oil (BNS28), benzophenone (premixed with the oil) and an antioxidant additive (Irganox B225).

[0061] By way of comparison, control compositions free of polyethylene and copolymer were tested, in which these compounds were replaced by TPV. In most cases these compositions did not lead to compositions that were employable, because the absence of polyethylene made the incorporation of the oil impossible. Only the control based on Optipren led to a homogeneous polymer composition.

[0062] The compositions of the formulas that were tested are stated in Table 1 above (amounts are in parts by weight per 100 parts by weight of the total composition)

TABLE-US-00001 TABLE 1 Composition of the compositions tested Composition C1 C2 C3 Control Moplen 56.6 0 LLDPE 28 TPV: Santoprene 203-40 9.4 Santoprene 203-50 9.4 OptiPren 9.4 94 Oil 5.4 Benzophenone 0.3 Antioxidant 0.3

[0063] The performance of the compositions thus prepared is reported in Table 2 below.

TABLE-US-00002 TABLE 2 Performance of the compositions tested Composition C1 C2 C3 Control Colour translucent translucent translucent translucent DSC .sup.[1] Melting temperature 124/147 123/146 123/144? C. 155? C. (2nd cycle) Onset of melting 118/137 119/137 119/135? C. 142? C. temperature (2nd cycle) Mechanical properties .sup.[2] TSP (MPa) 31.2 28.6 31.2 16.2 EB (%) 909 909 916 750 Measurements after thermal ageing (after 10 days at 135? C.) ?TSP ?19% ?12% ?18% +6% ?EB ?27 ?23 ?23% +23% Measurement of thermopression .sup.[3] Indentation value 3 2 3 23 (%) Elongation when cold .sup.[4] Elongation 687 503 694 >800 (%) Water uptake .sup.[5] Weight gain 0.17 0.14 (mg/cm.sup.2) Dielectric spectroscopy .sup.[6] tan (?) 110? C. 1.22 .Math. 10.sup.?3 2.4 .Math. 10.sup.?2 90? C. 4.18 .Math. 10.sup.?4 2.4 .Math. 10.sup.?4 1.83 .Math. 10.sup.?4 1.1 .Math. 10.sup.?2 70? C. 3.42 .Math. 10.sup.?4 2.9 .Math. 10.sup.?3 30? C. 4.97 .Math. 10.sup.?4 8.2 .Math. 10.sup.?5 2.9 .Math. 10.sup.?4 Permittivity 110? C. 2.13 1.94 90? C. 2.22 2.22 2.20 2.00 70? C. 2.25 2.05 30? C. 2.33 2.33 2.31 2.13 Notes: .sup.[1] DSC measurement under a stream of nitrogen, 3 cycles of temperature rise from ?20? C. to +250? C. at a rate of 10? C./min .sup.[2] Measured on the Instron at ?250 mm/min - median of 5 .sup.[3] Indentation value expressed as a percentage .sup.[4] Measurement at ?25? C. .sup.[5] Measurement carried out after treatment for 336 h at 85? C. .sup.[6] Standard = max tan (?) 30? C. = 4.10.sup.?3; max tan (?) 90? C. = 8.10.sup.?3