FR2765384A1 - ELECTRICALLY CONDUCTIVE WIRE - Google Patents

Abstract

Electric conductor wire (1) comprises a synthetic, preferably polyamide, monofilament core (2) with an outer coating (3) of electrically conducting particles, preferably powdered metal or carbon, forming a continuous conducting layer covering the whole surface of the core. Preferably the core has a round, stellate or toothed cross-section, and the outer conducting layer can itself by covered with an insulating coating. The central electrical conductor is embedded inside a core of synthetic material, coated by conducting particles and covered with an insulating layer to make a coaxial cable.

Description

The present invention relates to an electrically conductive wire, this wire

  being intended, more particularly but not exclusively, to replace the current wires or braids used for the production of electric fences. A first known type of wire for electric fences consists of a core in the form of a synthetic monofilament, around which is wound in a helix at least one electrically conductive wire. The synthetic monofilament, in particular made of polyamide or polyester, with a diameter of the order of 1 to 2 mm, is very oriented so as to have good mechanical strength, and it is very little shrunk so that it cannot be relax under the effect of humidity, rain or solar radiation. The electrically conductive wires, one, two or more in number, of small cross section relative to that of the core, are wound by covering, with a greater or lesser helix pitch, around the core. These conductive wires are made of metal or alloy, preferably of stainless steel to prevent rust on contact with rain and humid air. A second known type of wire for electric fences comprises, instead of the core of the previous type, synthetic multifilaments which are assembled, twisted and cabled. In these multifilaments are inserted one or more electrically conductive wires, in particular made of stainless steel. This second type has the advantage of being more flexible than the first, and of requiring lower quality elementary wires. A third type of conductor for electric fences consists of a braid of flat shape, more or less wide, made from multiple filaments, some being synthetic filaments and the others being constituted by one or more electrically conductive wires, inserted between the synthetic filaments, the product thus obtained being relatively solid. In all cases, the wires or braids for electric fences therefore result from the assembly of at least one plastic wire, therefore electrically insulating, and one or more electrically conductive wires, preferably stainless steel, which appear on the surface of the final product. Such conductive wires are relatively expensive and, in order to overcome cost problems, manufacturers tend to reduce the diameter of these conductive wires, therefore increasing the risk of breakage of said wires, which obviously makes the electric fence unsuitable for its use since the

  continuity of the electrical circuit is then broken.

  Furthermore, the plastic parts of wires or braids for electric fences are exposed to solar ultraviolet radiation, and to increase the longevity of these wires or braids, their plastic parts are additivated with anti-ultraviolet agents. However, these agents are themselves gradually destroyed by ultraviolet rays, and

  after a few years, they lose their effect. Thus the benefit of such agents remains quite low, and it should also be noted that anti-ultraviolet agents are expensive substances.

  It should also be noted, from the point of view of the manufacture of wires or braids for electric fences, that all known types require reworking of monofilaments or multifilaments, on wrapping, wiring or braiding machines, which complicates and

  increases the processes for obtaining these products.

  The present invention aims to remedy all of these drawbacks by proposing an electrically conductive wire of new design, usable in particular as wire for electric fences, which is simple and economical to manufacture, which is resistant to ultraviolet rays and weathering, and that removes the

  risk of breaking the current conductor wires.

  To this end, the subject of the invention is essentially an electrically conductive wire, which comprises a monofilament type core, made of synthetic material, which is coated with a coating formed of electrically conductive particles, forming a layer longitudinally.

  continuous, electrically conductive.

  The conductive coating results in particular from the application, to the outer surface of the core wire, of an electrically conductive metal or carbon powder. An electrically conductive wire is thus obtained, and more particularly a surface conductive wire, composed of an insulating core conferring on the wire its mechanical characteristics, and of a conductive coating whose thickness determines the cross section of the

Electric power.

  The conductive wire thus obtained has good mechanical and electrical characteristics. In particular, it is less fragile than a conventional wire or braid for electric fences, the presence of a continuous conductive outer layer eliminating the risk of breakage of a conductive wire of small section. The conductive coating, constituting a continuous layer preferably covering over its entire circumference the core of synthetic material, ensures total opacity to ultraviolet rays, protecting the core against any

degradation due to radiation.

  Such an electrically conductive wire can be obtained industrially in a rational and economical manner, the conductive coating being able to be applied to the core of synthetic material by a coextrusion, coating or soaking process, carried out continuously. In particular, the process for obtaining the electrically conductive wire, object of the invention, can consist, on an extruded and drawn core wire running continuously, by coating with an adhesion agent, followed by dusting. conductive particles intended to form the electrically conductive layer, then baking definitively fixing the conductive coating on the core wire. The electrically conductive wire, finally obtained, can be easily wound on coils, without

  degradation of its electrical characteristics.

  The core wire can, in a simple embodiment, have a round section. It can also have a star or serrated profile, which has the first advantage of increasing the adhesion surface of the conductive coating, and of improving the attachment of the latter to the core wire. An additional advantage of this configuration is to guarantee electrical continuity, even in the event of scratching or external wear of the wire, because the conductive particles located at the bottom of the grooves, located between the "teeth" of the core, are put protected from scratches or other surface aggressions of the wire. Of course, in the case of an electrically conductive wire applied to the production of electric fences, the layer formed by the electrically conductive particles necessarily forms the

outer surface of said wire.

  However, for other applications, the layer formed by the electrically conductive particles may itself be covered with an insulating coating, which then forms the outer surface of the wire which is the subject of the present invention. A particular application, coming within the framework of this latter embodiment of the invention, is the production of a coaxial cable, in which an electrically conductive central wire is embedded in the insulating core, of synthetic material, surrounded by the conductive layer formed by the electrically conductive particles, this conductive layer itself being covered with an insulating coating. The layer formed of electrically conductive particles here replaces the traditional copper braid of coaxial cables, such as those used in the field of television, which leads to a simpler structure and more economical manufacture of this kind of electric cables. In any case, the invention will be better understood at

  using the following description, with reference to the drawing

  attached schematic showing, by way of nonlimiting examples, some embodiments of this electrically conductive wire, and illustrating its mode of production: Figure 1 is a perspective view of a section of conductive wire according to the present invention ; Figure 2 is a perspective view of another section of conductive wire, constituting a variant of the previous one; Figure 3 is a block diagram of a process, and the corresponding installation, for the manufacture of a conductive wire according to the invention;

  Figure 4 illustrates another embodiment of this conductive wire, constituting a coaxial cable.

  Figure 1 shows a short section of an electrically conductive wire 1, which can be in particular a wire for electric fencing, showing the section of this wire. The conducting wire 1 consists of a core wire 2, here of round section, which is coated on all sides with an electrically conducting coating 3, forming

  in particular the outer surface 4 of said wire 1.

  The core wire 2 is a wire of polyamide or other synthetic material, electrically insulating, of the monofilament type. The conductive coating 3 consists of fine particles of electrically conductive metal, preferably stainless, or carbon. This coating 3 forms a continuous electrically conductive layer, of annular section, allowing the passage of electric current from one point to another of the wire 1, whatever the distance of these points. The presence of this conductive layer on the surface 4 of the wire makes it suitable for constituting a wire for electric fencing. Figure 2 also shows a short stretch of

  common thread 1, constituting a variant of the previous one.

  The core wire 2 of insulating synthetic material has here a star or serrated section, which increases the adhesion surface of the conductive coating 3, and which guarantees the longitudinal continuity of the conductive layer. Indeed, the conductive material located at the bottom of the longitudinal grooves of the core 2, formed between the teeth 5 of this core, is preserved in the event of

  local degradation of the outer surface 4 of the wire 1.

  FIG. 3 illustrates the production of the thread 1 previously described, according to a particular method. The core wire 2 made of synthetic material, previously manufactured by extrusion and drawing, runs continuously according to the arrow 6. On the core wire 2 is carried out, by a suitable projection or application device 7, a coating with an adhesive agent 8. Next, a powdering device 9 projects the conductive particles 10, such as metal powder, onto the core wire 2, intended to form the conductive coating 3. The assembly finally passes through a baking oven 11, which definitively fixes the conductive coating 3, formed of particles 10, on the core wire 2, so as to obtain at the outlet the conductive wire 1 corresponding to the

  description given above with reference to FIGS. 1 and

  2. This lead wire 1 can be finally wound around

  of a take-up reel, not shown.

  Figure 4 shows another conductive wire 1 according to the invention, which constitutes a coaxial cable such as those used in the field of television. This wire 1 also comprises an insulating core 2, coated with a conductive coating 3. In the core 2, still made of insulating synthetic material, there is embedded an electrically conductive central wire 12, such as a weak copper wire section. The conductive coating 3, consisting of a metal or carbon powder applied to the core 2, is itself covered by an insulating coating 13, of the sheath type, forming the outer surface of the coaxial cable. The conductive coating 3 of the core 2 here constitutes the outer conductor, of annular section, of the coaxial cable and it replaces the copper braid traditionally included in the coaxial cables. It goes without saying that the invention is not limited to the sole embodiments of this electrically conductive wire which have been described above, by way of examples; on the contrary, it embraces all of the variant embodiments and applications respecting the same principle. In particular, one would not depart from the scope of the invention by modifying the material of the core wire, or its section, or by using particles of any suitable conductive material and of various particle sizes to form the coating. conductive, or by applying and fixing this conductive coating on the core wire by other methods than that described and illustrated. It should also be noted that the conductive coating does not necessarily form a layer covering the core over its entire circumference; it is possible to envisage a conductive layer covering only partially the core, in particular a conductive layer subdivided in the form of parallel, rectilinear strips or wound in a helix around the core, which can provide an economy of conductive material (however by correspondingly reducing the

  protection of the soul from ultraviolet rays).

  Furthermore, the uses of this electrically conductive wire are not limited to electric fences and coaxial cables, and include other

  electrical applications in particular at low voltage, for which the conductive coating offers a sufficient cross-section for the electric current, without presenting any danger.

Claims (8)

  1 - Electrically conductive wire, characterized in that it comprises a core (2) of monofilament type, made of synthetic material, which is coated with a coating (3) formed of electrically conductive particles, forming a longitudinally continuous, electrically conductive layer . 2 - Electrically conductive wire according to claim 1, characterized in that its core (2) is   constituted by a polyamide monofilament.   3 - Electrically conductive wire according to claim 1 or 2, characterized in that the conductive coating (3) results from the application, on the outer surface of the core wire (2), of a metal powder   electrically conductive or carbon.   4 - Electrically conductive wire according to one   any one of claims 1 to 3, characterized in that   the conductive coating (3) constitutes a continuous layer covering over its entire circumference the core (2) of synthetic material. - Electrically conductive wire according to one   any one of claims 1 to 4, characterized in that   that its soul (2) has a round section.   6 - Electrically conductive wire according to one   any one of claims 1 to 4, characterized in that   its core (2) has a star or serrated profile.   7 - Electrically conductive wire according to one   any of claims 1 to 6, characterized in that   the layer formed by the electrically conductive particles (3) forms the outer surface (4) of said wire (1). 8 - electrically conductive wire according to claim 7, characterized in that it constitutes a wire (1) for electric fences.   9 - Electrically conductive wire according to one   any of claims 1 to 6, characterized in that   the layer formed by the electrically conductive particles (3) is itself covered with an insulating coating (13), which forms the outer surface wire (1).   - Electrically conductive wire according to claim 9, characterized in that it constitutes a coaxial cable (1), in which a central electrically conductive wire (12) is embedded in the core (2) of synthetic material, surrounded by the layer conductive formed by the electrically conductive particles (3), this conductive layer being itself covered with a insulating coating (13).   11 - Electrically conductive wire according to one   any one of claims 1 to 10, characterized in that   that the conductive coating (3) is applied to the core (2) of synthetic material by a coextrusion process,   coating or soaking, implemented continuously.   12 - Electrically conductive wire according to claim 11, characterized in that it is obtained by proceeding, on a core wire (2) extruded and drawn continuously scrolling, to a coating with an adhesive agent (8), followed by a dusting of the particles (10) intended to form the electrically conductive layer (3), then by baking permanently fixing the coating   conductor (3) on the core wire (2).