Reflective protective sheath for a cable

Abstract

The present invention relates to a cable (1) comprising one or more elongated conductive elements (11), said elongated conductive element or the set of said elongated conductive elements (11) being surrounded by a protective sheath (20), characterized in that the outer surface and/or the inner surface of the protective sheath comprises at least one longitudinal groove (21) in which is positioned at least one reflective longitudinal element (30) obtained from a first composition comprising a first polymer material and at least one reflective filler.

Claims

1. Cable comprising: one or more elongated conductive elements, said elongated conductive element or the set of said elongated conductive elements being surrounded by a protective sheath, wherein the outer surface and/or the inner surface of the protective sheath comprises at least one longitudinal groove in which is positioned at least one reflective longitudinal element obtained from a first composition comprising a first polymer material and at least one reflective filler.

2. Cable according to claim 1, wherein the first polymer material comprises at least one polymer A having a glass transition temperature (Tg) of at most 10 C., and preferably of at most 0 C.

3. Cable according to claim 1, wherein the first polymer material comprises at least one polymer A chosen from a thermoplastic polyurethane elastomer (TPU), a chlorinated polyethylene (CPE), and a mixture thereof.

4. Cable according to claim 1, wherein the reflective filler is of micrometre size.

5. Cable according to claim 1, wherein the reflective filler is chosen from metal particles, metallized particles, inorganic particles with a refractive index of greater than or equal to 1.5, and a mixture thereof.

6. Cable according to claim 5, wherein the metal particles or the metallized particles have a shape factor of strictly greater than 1.

7. Cable according to claim 5, wherein the inorganic particles may be particles based on silicon dioxide.

8. Cable according to claim 7, wherein the particles based on silicon dioxide are glass beads.

9. Cable according to claim 1, wherein the first composition further comprises an additive D intended to improve the optical reflection of the reflective filler.

10. Cable according to claim 9, wherein the additive D is of micrometre size.

11. Cable according to claim 9, wherein the additive D is chosen from metal particles, particles derived from a metal, and a mixture thereof.

12. Cable according to claim 1, wherein the protective sheath is obtained from a second composition comprising a second polymer B having a glass transition temperature (Tg) of at most 10 C., and preferably of at most 0 C.

13. Cable according to claim 12, wherein the second polymer B is chosen from a thermoplastic polyurethane elastomer (TPU), a chlorinated polyethylene (CPE), and a mixture thereof.

14. Cable according to claim 1, wherein, when the inner surface of the protective sheath comprises at least one longitudinal groove in which said reflective longitudinal element is positioned, the protective sheath is a transparent or translucent sheath.

15. Cable according to claim 1, wherein the depth of the groove (21) does not exceed three quarters of the maximum thickness of the protective sheath.

16. Cable according to claim 1, wherein the protective sheath comprises at least two longitudinal grooves on the same surface, each longitudinal groove being placed equidistant from one another.

17. Cable according to claim 1, wherein the protective sheath comprises at least two longitudinal grooves on the same surface, each longitudinal groove being parallel to one another.

18. Process for manufacturing a cable according to claim 1, wherein the process comprises the step of: co-extruding the protective sheath together with the reflective longitudinal element.

Description

[0124] Other features and advantages of the present invention will become apparent in light of the description of nonlimiting examples, and figures.

[0125] FIG. 1 represents a schematic cross-sectional view of a cable according to a first embodiment of the invention.

[0126] FIG. 2 represents a schematic cross-sectional view of a cable according to a second embodiment of the invention.

[0127] FIG. 3 represents a schematic cross-sectional view of a cable according to a third embodiment of the invention.

[0128] For reasons of clarity, only the elements essential to the understanding of the invention have been represented schematically, this not being done to scale.

[0129] FIG. 1 represents a cross-sectional view of an electric cable 1A according to a first embodiment in accordance with the invention. Said electric cable 1 comprises a set 10 of three insulated electrical conductors, each insulated electrical conductor comprising an electrical conductor 11 surrounded by an electrically insulating layer 12.

[0130] The set 10 of these three insulated electrical conductors is surrounded by a protective sheath 20A in accordance with the invention.

[0131] This protective sheath 20A comprises, on its outer surface, six V-shaped longitudinal grooves 21A in the thickness of said protective sheath.

[0132] These six grooves are positioned substantially equidistant from one another, and more particularly at around 60 from one another. Moreover, the inner surface of the protective sheath 20A comprises no longitudinal groove.

[0133] This grooved protective sheath 20A depicted in FIG. 1 is referred to as a tubing sheath. It is obtained by a continuous extrusion process, well known to a person skilled in the art. This protective sheath 20A is preferably a non-transparent and non-translucent sheath. It may be coloured.

[0134] Each of the six grooves is completely filled by a reflective longitudinal element 30 obtained for example from one of the compositions C1 to C6 as described in Table 1 below.

[0135] The sheath 20A and also the six reflective elements 30 are obtained by simultaneously extruding the composition of the protective sheath (i.e. second composition) and the composition of the reflective elements (i.e. first composition).

[0136] FIG. 2 represents a cross-sectional view of an electric cable 1B according to a second embodiment in accordance with the invention. Said electric cable 1B comprises a set 10 of three insulated electrical conductors, each insulated electrical conductor comprising an electrical conductor 11 surrounded by an electrically insulating layer 12.

[0137] The set 10 of these three insulated electrical conductors is surrounded by a protective sheath 20B in accordance with the invention.

[0138] This protective sheath 20B comprises, on its inner surface, three V-shaped longitudinal grooves 21B in the thickness of said protective sheath.

[0139] These three grooves are positioned substantially equidistant from one another, and more particularly at around 120 from one another. Moreover, the outer surface of the protective sheath 20B comprises no longitudinal groove.

[0140] This grooved protective sheath 20B depicted in FIG. 2 is referred to as a tubing sheath. It is obtained by a continuous extrusion process, well known to a person skilled in the art. This protective sheath 20B is preferably a transparent or translucent sheath.

[0141] Each of the three grooves is completely filled by a reflective longitudinal element 30 obtained for example from one of the compositions C1 to C6 as described in Table 1 below.

[0142] The sheath 20B and also the three reflective elements 30 are obtained by simultaneously extruding the composition of the protective sheath (i.e. second composition) and the composition of the reflective elements (i.e. first composition).

[0143] FIG. 3 represents a cross-sectional view of an electric cable 1AB according to a third embodiment in accordance with the invention. Said electric cable 1AB comprises a set 10 of three insulated electrical conductors, each insulated electrical conductor comprising an electrical conductor 11 surrounded by an electrically insulating layer 12.

[0144] The set 10 of these three insulated electrical conductors is surrounded by a protective sheath 20AB in accordance with the invention.

[0145] This protective sheath 20AB comprises, on its outer surface, six V-shaped longitudinal grooves 21A in the thickness of said protective sheath. These six grooves are positioned substantially equidistant from one another, and more particularly at around 60 from one another.

[0146] This protective sheath 20AB further comprises, on its inner surface, three V-shaped longitudinal grooves 21B in the thickness of said protective sheath. These three grooves are positioned substantially equidistant from one another, and more particularly at around 120 from one another.

[0147] This grooved protective sheath 20AB depicted in FIG. 3 is referred to as a tubing sheath. It is obtained by a continuous extrusion process, well known to a person skilled in the art. This protective sheath 20AB is preferably a transparent or translucent sheath.

[0148] Each of the grooves 21A and 21B, namely nine grooves in total, is completely filled by a reflective longitudinal element 30 obtained for example from one of the compositions C1 to C6 as described in Table 1 below.

[0149] The sheath 20AB and also the nine reflective elements 30 are obtained by simultaneously extruding the composition of the protective sheath (i.e. second composition) and the composition of the reflective elements (i.e. first composition).

[0150] Owing to the particular structure of the cables of the invention, the latter retain their reflective properties, even in environments subjected to high mechanical stresses, such as in mines.

EXAMPLES

[0151] The abrasion properties of a reflective element according to the invention were tested.

[0152] Table 1 below assembles the compounds used to produce first compositions (C1 to C6) in accordance with the invention.

[0153] The amounts of the compounds are expressed in parts by weight per 100 parts by weight of polymer material (i.e. first polymer material) in the first composition.

[0154] The polymer material in Table 1 is composed either of a single chlorinated polyethylene (CPE), or of a single thermoplastic polyurethane elastomer (TPU).

TABLE-US-00001 TABLE 1 First composition C1 C2 C3 C4 C5 C6 CPE 1 100 0 100 0 0 0 CPE 2 0 100 0 100 0 0 TPU 0 0 0 0 100 100 Reflective filler 1 0 0 6 6 0 6 Reflective filler 2 50 50 0 0 50 0 Additive D 0.1 0.1 0 0 0.1 0

[0155] The origin of the compounds from Table 1 is the following: [0156] CPE 1 is a chlorinated polyethylene sold by BETAQUIMICA under the reference 1462 (Tg of CPE 1 equal to 25 C.); [0157] CPE 2 is a chlorinated polyethylene sold by DOW under the reference TYRIN 3551 (Tg of CPE 2 equal to 25 C.); [0158] TPU is a thermoplastic polyurethane elastomer sold by BASF under the reference TPU ELASTOLLAN 1185 A10 U (Tg of TPU equal to 42 C.); [0159] Reflective filler 1 corresponds to metallized polyester glitter, with dimensions of 400 m400 m30 m, sold by MINERAL COLOR under the reference Glitter. [0160] Reflective filler 2 corresponds to glass beads with a diameter of 60 m, sold by POTTERS under the reference Glass Microbeads; [0161] Additive D corresponds to a paste containing aluminium particles (80% by weight of the paste) dispersed in a mineral oil (20% by weight of the paste), said particles being of micrometre dimensions (at least one of their dimensions is 15 m), sold by ECKART under the reference Aluminium Paste STAPA WM Chromal V/80.

[0162] From the compositions of Table 1, films around 2-3 mm thick are manufactured by compression-moulding in order to perform the TABER abrasion test (with the Taber 5700 linear abraser) according to the following conditions: [0163] 25 cycles/min; [0164] 1000 cycles; [0165] load: 1.1 kg; [0166] abrasion length: 7.62 cm.

[0167] The compositions from Table 1 used for the abrasion test are not crosslinked compositions.

[0168] This abrasion test makes it possible to obtain a weight loss in milligrammes (mg).

[0169] The results of this test are assembled in Table 2 below:

TABLE-US-00002 TABLE 2 Abrasion test (TABER) C1 C2 C3 C4 C5 C6 Weight loss (mg) 146 188 159 200 32 29

[0170] The weight losses generated by the abrasion remain relatively small, which guarantees good optical reflection properties throughout the lifetime of the cable.