FR2643854A1 - Road-marking grid and device for manufacturing it - Google Patents

Abstract

The invention relates to a road-marking grid. It comprises, in combination, a reticular structure composed of filaments oriented in at least two directions, and a surface road-marking layer deposited on at least one of the faces of at least some of the filaments of the said reticular structure. A device for the manufacture of this grid comprises a first stationary die element 1 and a second die element 2 which can move and is driven in a to-and-fro movement, at least one of the said elements including catches 4 making extrusion orifices between the two elements. It comprises secondary extrusion channels 6 for extruding the said surface layer, the said channels emerging in the vicinity of the said extrusion orifices.

Description

 The present invention relates to a marking mesh and a device for its manufacture.

 Many beaconing devices are known which are made from glass beads embedded in a suitable support such as a paint or a reflective adhesive, or based on a fluorescent or photoluminescent compound.

 There are also known extruded markers, but so far such gratings have never been made, so as to be themselves reflective, fluorescent or photoluminescent.

 It is indeed not possible to mix the glass beads directly with the material of the mesh before its extrusion, since a much too large quantity of beads would be necessary, which would make the finished product unnecessarily expensive, most of the beads indeed finding themselves drowned in its mass and not distributed on its surface. On the other hand, the balls would cause rapid wear of the mesh extrusion dies.

 It is also difficult to implant glass beads after extrusion of the mesh if one wishes to obtain a regular distribution of these beads and a satisfactory connection with the support.

 Furthermore, the fluorescent or photolumine concept compounds degrade at the screen extrusion temperature, so that one cannot envisage coextruding the screen and a fluorescent compound.

 In addition, these compounds are expensive and it is therefore essential to use as little as possible.

 The present invention aims to overcome these drawbacks.

 To this end, the invention firstly relates to a marking mesh, characterized in that it comprises in combination a reticular structure composed of filaments oriented in at least two directions, and a surface layer of marking deposited on at least one of the faces of at least some of the filaments of said reticular structure.

 This surface layer can consist of glass beads incorporated into a binder, hence a fluorescent or photoluminescent compound.

 One can more particularly use a reticular structure comprising longitudinal filaments and transverse filaments, the surface layer then being arranged on at least one of the faces of at least some of the longitudinal filaments.

 This structure in two layers at the level of all the filaments or only of some of them, for example the longitudinal filaments have the advantage of being able to be produced directly by extrusion, which eliminates the difficulties linked to the implantation of the balls. glass or fluorescent or photoluminescent compound after extrusion.

 Furthermore, the glass beads or the fluorescent compound are thus distributed over a thin layer extruded on the surface of the mesh, which avoids using large quantities which would be embedded in the mass of the mesh.

 Of course, one can provide a mesh consisting at least in part of three layers, the two outer layers of which are reflective, fluorescent or photoluminescent.

 The mesh coated with its surface layer can then be optionally stretched longitudinally, which has the effect of reducing the thickness of this layer, and therefore, in the case of beads incorporated into a binder, to bring them out to the surface. layer, giving them greater efficiency.

 The present invention also relates to a device for the manufacture of a mesh as described above, comprising in known manner a first fixed die element and a second movable die element animated by a back and forth movement. comes, at least one of said elements comprising notches providing extrusion orifices between the two elements, characterized in that it comprises secondary extrusion channels for the extrusion of said surface layer, said channels opening out in the vicinity of said extrusion orifices.

 Such an arrangement makes it possible to solve the problem of abrasion of the dies in the case where the surface layer comprises glass beads, and of the temperature resistance of this layer in the case of a fluorescent or photoluminescent compound.

A particular embodiment of the invention will now be described by way of nonlimiting example with reference to the appended schematic drawings in which
FIG. 1 is a view in axial half-section of a first embodiment of a device according to the invention,
FIG. 2 is a view on a larger scale in section along the line Il-Il of FIG. I,
FIG. 3 is a view also on a larger scale according to arrow III in FIG. 1,
FIG. 4 is a view in axial half-section of a device according to a second embodiment,
FIG. 5 is a view on a larger scale along the arrow V in FIG. 4, and
-the ìgue 6 is a plan view of a reflective mesh according to the invention.

 The two embodiments comprise, in a known manner, a first fixed central die element I and a second die element 2 in the form of a crown movable vertically under the action of operating members such as jacks, so as to effect a movement. vertical oscillation in the direction of the arrow FI between a low position illustrated in the drawings, and a high position.

 A fixed central body 10 cleans with the die element 1 an annular channel 3 intended for the arrival of the material to form the grid.

 At the flared lower part of the annular channel 3, the die elements are in contact when they are in the close position, while they provide an annular opening between them when they are in the separated position.

 In the case of Figures 1 to 3, the element 2 has notches 4 while in the embodiment of Figures 4 and 5, the element 1 has notches 4 '.

 When the die elements 1 and 2 are in their close position, the molten material comes out only through the notches 4 or 4 ′, thus forming longitudinal filaments.

 When, on the other hand, these elements are in the separated position, the material comes out all around the annular opening thus formed, thereby producing transverse filaments.

 The mesh sheet once formed between the die elements passes over a shaper 5 arranged coaxially with the assembly which has just been described.

 In the embodiment of the invention described in FIGS. 1 to 3, channels 6 are formed in the central body 10.

 These channels 6 open at their upper part into an annular supply duct 7 and at their lower part immediately upstream of the die element 2 opposite the notches 4 of the element 2.

 Conversely in the embodiment of Figures 4 and 5, conduits 6 'are formed in the die element 1 and open at one of their ends in a central supply conduit 7' and at their other end at the notches 4 'of the die element 1.

 Thus, while making the grid in a known manner, for example in high density polyethylene, it is possible simultaneously to apply either to the external face of this grid (case of FIGS. I to 3) or to its internal face (case of FIGS. 4 and 5 ), a surface layer consisting of a binder, such as a polymer whose melting temperature is substantially lower than that of the material of layer 8 (for example a polymer of ethylene vinyl acetate) in which glass beads are incorporated and which is brought in via channels 6 and 6 t respectively.

 This gives a structure as shown in Figure 6 composed of two layers, namely a layer 8 of mesh on which is applied the surface layer 9 of binder in which are incorporated glass beads to form reflective strips.

 Various variants and modifications can of course be made to the above description without departing from the scope or the spirit of the invention.

Claims (6)

 I. Marking grid, characterized in that it comprises in combination a reticular structure (8) composed of filaments oriented in at least two directions, and a surface layer (9) of beacon deposited on at least one of the faces of at least some of the filaments of said reticular structure.  2. Mesh according to claim 1, characterized in that said surface layer comprises glass beads incorporated into a binder.  3. Mesh according to claim I, characterized in that said surface layer comprises a fluorescent or photoluminescent compound.  4. Mesh according to any one of claims 1 to 3, characterized in that said reticular structure comprises longitudinal filaments and transverse filaments, said surface layer being disposed on at least one of the faces of at least some of the longitudinal filaments .  5. Mesh according to any one of claims 1 to 4, characterized in that it is stretched longitudinally.  6. Device for manufacturing a mesh according to any one of claims I to 5, comprising a first fixed die element (1) and a second die element (2) movable and driven by a movement of- back and forth, at least one of said elements comprising notches (4,4 ') providing extrusion orifices between the two elements, characterized in that it comprises secondary extrusion channels (6,6' ) for the extrusion of said surface layer, said channels opening in the vicinity of said extrusion orifices.