EP4222315A1

EP4222315A1 - Resilient sole and method for manufacturing same

Info

Publication number: EP4222315A1
Application number: EP21783281.5A
Authority: EP
Inventors: Olivier PRUD'HOMME; Said SEGHAR
Original assignee: Rubbergreen Industrie
Current assignee: Rubbergreen Industrie
Priority date: 2020-10-02
Filing date: 2021-09-29
Publication date: 2023-08-09
Anticipated expiration: 2041-09-29
Also published as: AU2021353966A1; MX2023003547A; CN116507774A; BR112023005362A2; EP4222315B1; CA3193873A1; BE1028667B1; AU2021353966A9; BE1028667A1; US20230304227A1; EP4222315C0; PL4222315T3; WO2022069512A1

Abstract

Resilient sole 1 which is attached to a concrete layer (2) or which is positioned between a concrete layer (2) and ballast (3), and which is formed by a layer (4) of recycled rubber, in the revulcanised state after devulcanisation, and a layer (5) of structured fibres which is arranged so as to be in contact with the rubber layer, the fibres being partially impregnated in the rubber layer and having a free thickness (8) of structured fibres, assembly comprising the sole and method for manufacturing same.

Description

“ELASTIC SOLE AND ITS MANUFACTURING METHOD”

The present invention relates to an elastic sole arranged to be fixed to a layer of concrete or interposed between a layer of concrete and a ballast as well as a method of manufacturing such an elastic sole.

The present invention also relates to an assembly comprising a layer of concrete and an elastic sole as mentioned above.

Such soles are well known in the state of the art.

In the field of construction, such soles are arranged to be fixed to layers or blocks of concrete.

In the field of railways, such soles are interposed between the sleepers and the ballast, the ballast constituting the bed of the railway.

The sleeper is a transverse piece of treated wood, steel or concrete on which the rails of a railway track are fixed in order to keep them parallel and to transmit the load they support to the ballast.

The ballast consists of crushed stones and is arranged to receive the sleepers on which the railway tracks rest.

The purpose of this type of padding between the ballast and the sleepers is to dampen the propagation of vibrations generated by the passage of the train on the rails towards the bed of the underlying railway and therefore towards the ballast, to avoid wear as well as the settling of the ballast as well as to avoid the wear of the sleepers and in particular of the concrete sleepers by the ballast. Indeed, without pads interposed between the ballast and the sleepers, the concrete sleepers would therefore be in direct contact with the crushed stones of the ballast. This would therefore lead to cracks and concrete becoming friable over time.

For example, document FR2935399 describes an elastic sole which is provided with wires forming stainless steel loops which are embedded in an extruded viscoelastic plate with a maximum of 4 loops per cm ² of extruded viscoelastic plate during molding. These wires are also embedded in the concrete block during the molding of the latter.

Unfortunately, these wires can easily detach from the viscoelastic plate in which they are directly embedded, deform or break easily due to shear stresses under the effect of repeated passages of trains on the rails of the railway.

In addition, the wires do not make it possible to obtain satisfactory adhesion of the concrete to the extruded viscoelastic plate.

Document WO2019201761 describes a sole comprising an elastic layer and a fiber layer which comprises various elements such as grooves, randomly arranged fibers and solidified zones. The solidified zones are obtained by heat treatment or local bonding of the fibers.

Unfortunately, the manufacture of this sole takes a considerable amount of time. The fibrous layer must be reinforced in certain places, the fibers must not be present or very little present in other places of the upper surface of the elastic layer and the reinforcements of certain places must be carried out by the addition of more fibers.

Document WO2012040798 describes an elastic sole comprising an elastic layer based on rubber and a ground sheet placed on the elastic layer. The floor mat comprises on the one hand a mat base in the form of an extruded film and on the other hand filaments which can be in the form of loops, mushrooms or hooks. The filaments are made of polymers and are attached to the extruded film by welding. The elastic layer and the extruded film are associated with each other by gluing or welding the base of the floor mat to the elastic layer.

Unfortunately, first of all this elastic sole is associated with a specific concrete whose manufacture is explained in the document. The filaments are affixed against the concrete milk during the hardening of the sleepers so as not to impact the resistance of the sleepers. This footing is therefore highly dependent on the quality of the concrete used to form the sleeper. In addition, this document is silent as to the resistance of the concrete sleepers, fibers and elastic layer assembly. However, it is likely that in the long term, the gluing or welding of the elastic layer at the base of the mat (extruded film) will be a source of fragility of the "concrete sleepers, fibers and elastic layer" assembly.

Document EP129852 describes an elastic sole comprising an extruded elastic layer and a plastic fibrous layer entangled in the extruded elastic layer by welding, the fibrous layer being composed of a nonwoven geotextile.

Unfortunately, the use of a geotextile-type textile involves a significant cost for the production of this type of elastic soles which are present under each sleeper of the railway. It is also likely that in the long term, as for the document WO2012040988, the welding of the elastic layer at the base of the geotextile or of a plastic non-woven fabric is a source of fragility of the assembly "concrete sleepers, fibers and elastic layer.

Patent application WO2009/108972 discloses an elastic sole to be fixed, for example, to concrete sleepers. This sole comprises several layers of elastomeric materials which are reinforced by a reinforcing layer placed between two elastomeric layers, and which are covered with a bonding layer intended for bonding with the concrete. During the manufacture of the sole, these reinforcing or bonding layers are, one totally, the other partially, embedded in the elastomer layers during the expansion reaction of the latter. Such soles are complex to manufacture and certainly do not allow manufacture from vulcanized rubber waste which is recycled.

The object of the invention is to overcome the drawbacks of the state of the art by providing a robust elastic sole arranged to give a "cross member-sole under sleeper" assembly the ability to resist the stresses exerted by the railway, from waste of vulcanized rubber, and using a simple and economical manufacturing process.

To solve this problem, there is provided according to the invention an elastic sole arranged to be fixed to a layer of concrete or interposed between a layer of concrete and a ballast, which consists of a layer of recycled rubber, in the state revulcanized after devulcanization, and a layer of structured fibers, placed in contact with the rubber layer, said fibers being partially impregnated in said rubber layer and having a thickness of free structured fibers. As can be seen, in the sole according to the present invention, the rubber layer of the elastic sole comes from a recycling sector and can include production waste, cutting waste or even used waste.

By the terms "structured fibers" is meant according to the invention, fibers entangled in a weft, or fibers arranged on several layers of superimposed textile fibers. These fibers can be intertwined during the manufacturing process using special hook needles to form a layer of dense and compact structured fibers which is optionally then coated in order to solidify the whole, such as for example felt or needled carpets frequently used for temporary events (exhibition stand, red carpet, etc.).

The structured fibers can come from the recycling sector. Depending on the type of structured fibers, as for example in the case of production waste, it is possible according to the present invention to use the structured fibers directly to form said layer of structured fibers of the elastic sole.

The rubber used in the elastic sole according to the present invention is a recycled rubber, more particularly a rubber which has been devulcanized. Devulcanized rubber is rubber that has been de-crosslinked, i.e. rubber in which some of the sulfur bonds have been broken.

The rubber is then revulcanized by a hot pressing process. The rubber obtained is therefore a rubber in which sulfur bonds are recreated during hot pressing.

According to the present invention, the structured fibers of the layer of structured fibers are partially impregnated in the layer of rubber. This impregnation takes place during the hot pressing of the formed layer of the devulcanized rubber. During hot pressing, the rubber is revulcanized in the thickness of the rubber layer, but also around structured fibers.

According to the present invention, by the terms "partially impregnated in the rubber layer", it is meant that the layer of structured fibers has a thickness of free structured fibers, that is to say not impregnated by the revulcanized rubber and a thickness of structured fibers impregnated in the revulcanized rubber.

Surprisingly, the combination of at least one layer of recycled rubber and at least one layer of structured fibers impregnated in the revulcanized rubber makes it possible to obtain a robust elastic sole that is resistant to tearing of the layer of fibers structured which are impregnated in the layer of revulcanized rubber according to the tests in force.

The tests in force are: the ISO 37 standard to measure tensile strength and Shore hardness, the EN 16730 standard to measure static and dynamic stiffness, resistance to ageing, resistance to fatigue and resistance to corrosion. uprooting.

In addition, when the undersole under the sleeper is associated with a concrete sleeper during the manufacture of the latter, the thickness of structured fibers not impregnated in the layer of revulcanized rubber is then impregnated in the concrete before hardening. Once the concrete has hardened, it has been identified in an equally surprising manner that the assembly has excellent resistance to tearing of the layer of structured fibers of the concrete. The layer of impregnated structured fibers is and then remains attached on the one hand to the rubber and on the other hand to the concrete during the pull-out tests, which makes it a sole resistant elastic against the stresses exerted, such as those exerted by the railway and its use. Advantageously, the resistance to tearing of the elastic sole according to the invention/rail sleeper exceeds 0.8 MPa.

Advantageously, the density of the structured fibers of the elastic sole according to the present invention is between 150 g/m ² and 800 g/m ² , preferably between 170 and 750 g/m ² , advantageously between 190 and 500 g/m ² . Such a density of structured fibers offers the advantage of increasing resistance to tearing during tests.

Advantageously, the fibers of the elastic sole according to the present invention are impregnated to a depth of between 0.5 and 2 mm, preferably between 0.7 and 1.5 mm, preferably between 0.9 and 1 mm in said layer revulcanized rubber. This has the advantage of creating a revulcanized rubber-fiber interphase that is robust and resistant to the stresses exerted by the railway. The fibre/rubber pull-out strength advantageously exceeds 1 MPa. This interphase allows the sole to have a resistance to the tearing of the concrete block when it is present as well as a resistance to the tearing of the rubber layer.

Preferably, said layer of devulcanized-revulcanized recycled rubber of the elastic sole according to the present invention has a Shore hardness of between 50 and 90 Shore A, according to the standard measurement model, the durometer. This has the advantage of obtaining a wide range of rubber stiffness and therefore of covering the needs of the various players in the target market.

Preferably, said devulcanized-revulcanized recycled rubber layer of the elastic sole according to the present invention has a tensile strength greater than or equal to 7 MPa, preferably greater than or equal to 8 MPa, advantageously greater than or equal to 9 MPa, even more advantageously equal to 10 MPa. This has the advantage that the layer of recycled rubber making up the elastic sole resists wear, for example the wear that the ballast causes following contact between the lower surface of the layer of recycled rubber and the ballast.

Preferably, said layer of devulcanized-revulcanized recycled rubber of the elastic sole according to the present invention has an elongation at break greater than 150%, preferably greater than 200%, or even greater than 250%. This has the advantage that the layer of recycled rubber making up the elastic sole is resistant to the various forces undergone by the sole and sufficiently rigid to fulfill its role of dissipating the vibrations to which the track is subjected.

Preferably, said fibers of the layer of structured fibers of the elastic sole according to the present invention are chosen from the group of natural or synthetic materials, such as for example polyester, polypropylene, polystyrene, polyethylene, wool, cotton , hemp, coconut fibers.

Advantageously, said rubber layer of the elastic sole according to the present invention comprises rubber chosen from the group of natural or synthetic materials, such as for example natural polyisoprene, isoprene polymer, polybutadiene, styrene-butadiene copolymer .

Other embodiments of the elastic sole according to the invention are indicated in the appended claims.

The present invention also relates to an assembly comprising a layer of concrete and an elastic sole as described above, in which said structured fibers are made of also partially impregnated in said concrete layer, on the thickness of free structured fibers.

Advantageously, the concrete layer can be a concrete block or a molded concrete element, advantageously a railway sleeper.

In one embodiment of the assembly according to the present invention, said fibers are impregnated in the layer of concrete of the assembly according to the present invention to a thickness of between 0.3 and 2 mm, preferably between 0.4 and 1.8 mm, more particularly between 0.5 and 1 mm. Advantageously, an impregnation of the fibers over such a thickness makes it possible to obtain an elastic sole assembly - integral concrete layer.

Other embodiments of the "concrete layer-elastic sole" assembly according to the invention are indicated in the appended claims.

Another object of the invention is to provide a production method which allows production in industrial quantities and at low cost of a quality elastic sole, robust and resistant to the stresses exerted for example by the regular passage of trains.

According to the invention, this problem is solved by a method of manufacturing an elastic sole comprising:

- devulcanization of recycled rubber, with formation of a mass of devulcanized recycled rubber,

- an addition of at least one adjuvant to the devulcanized recycled rubber, - a superposition of a layer of structured fibers and devulcanized recycled rubber with the obtaining of two superimposed layers, and

- hot pressing of said two superposed layers at a temperature of between 100 and 180°C for a predetermined time interval with revulcanization of the devulcanized recycled rubber and formation of an elastic sole in which the structured fibers are at least partially impregnated in said layer of rubber being revulcanized by forming a revulcanized rubber-fiber interphase.

The method of manufacturing an elastic sole according to the present invention has the advantage of producing, from rubber waste, an elastic sole simply and quickly, at low cost, making it possible to meet the requirements of each actor in the market. The sole is made from two layers, without any bonding between them.

Devulcanized rubber, which is recycled rubber, is obtained by devulcanization. This devulcanization can be carried out at the beginning of the manufacture of the elastic sole or else it can be carried out upstream of the manufacture of said elastic sole.

More particularly, this devulcanized rubber is a devulcanized rubber, reactivated by the addition of at least one adjuvant.

The layer of structured fibers is, by superimposition, brought into contact with said layer of devulcanized rubber, before pressing. This step makes it possible to obtain two superimposed layers.

The two superimposed layers are brought to a press and then hot pressed at a temperature between 100 and 180°C, preferably between 140 and 170°C, preferably between 150°C and 160°C for a predetermined time interval. This hot pressing will thus allow the revulcanization of the layer of devulcanized rubber and, during this revulcanization, an at least partial impregnation of the structured fibers of the layer of structured fibers in the layer of rubber thus forming a revulcanized rubber-fiber interphase. Thus, during hot pressing, the rubber is revulcanized in the thickness of the rubber layer, but also around structured fibers. Structured fibers have a melting temperature higher than the hot pressing temperature.

According to the present invention, the pressing is the result of the effort necessary to compress the rubber. The hot pressing can be carried out by any device known for this purpose, in particular in a mold or even between two pressing bands. The pressing bands are set to a layer thickness between 10 and 25% less than the thickness of the two superimposed layers.

According to the present invention, by the term revulcanized rubber, it is meant that the rubber is a rubber in which sulfur bonds are recreated during hot pressing.

By the terms, reactivated devulcanized rubber, is meant according to the present invention, a rubber whose reactivation of the sulfur bonds is ready to be initiated.

According to the present invention, by the terms "partial impregnation of the structured fibers", it is meant that the layer of structured fibers has, at the end of the process, a thickness of free structured fibers, that is to say not impregnated in the rubber. revulcanized and a layer of structured fibers impregnated in the revulcanized rubber. The method of manufacturing an elastic sole according to the present invention has the advantage of providing a resistant, robust and quality sole.

During devulcanization, it is advantageous for the viscosity of the devulcanized rubber to be less than 70 MU, preferably less than 50 MU, more particularly less than 40 MU, measured on a Mooney viscometer. This viscosity will promote the formation of a revulcanized rubber-fiber interphase by at least partial impregnation of the fibers of the fibrous structure in the rubber layer obtained during hot pressing. It is preferable, but not excluded, that there is not a total impregnation of the fibers during the compression step.

In addition, this viscosity will make it possible to produce varied elastic soles that will be able to meet the expectations of each of the players in the target market. Indeed, the manufacturing process makes it possible to obtain elastic soles in a wide range of sole rigidities.

In addition, the method of manufacturing an elastic sole according to the present invention has the advantage of being produced at low cost by using a rubber from the recycling sector and a layer of structured fibers whose the basic characteristics make it possible to obtain it at low cost. It therefore allows a circular economy by using business waste to give it a new life in another technical field.

The dependent claims refer to further advantageous embodiments.

In a preferred embodiment, the adjuvant(s) used in the addition step comprise sulfur and/or at least one resin and/or at least one reaction activator or accelerator and/or carbon black.

Advantageously, said at least one resin according to the present invention is a thermoplastic resin chosen from the group comprising resins having at least one phenol group, at least one aromatic group, at least one styrene group, or any other resin that can be used with sulfur vulcanized rubber or a combination thereof.

Preferably, said at least one reaction activator or accelerator according to the present invention is chosen from the group comprising CBS, stearic acid, zinc oxide.

Advantageously, said predetermined time interval of the hot pressing step of the method of manufacturing the sole according to the present invention is between 3 and 12 minutes, preferably between 4 and 10 minutes, more particularly between 5 and 6 minutes. .

According to an advantageous embodiment of the invention, after the addition of at least one aforesaid adjuvant, the mass of devulcanized recycled rubber is shaped and the layer of structured fibers and the devulcanized recycled rubber, shaped , are superposed so as to form said two layers.

It can occur, in certain cases, a total impregnation of the fibers in the layer of rubber in the course of revulcanization, during the hot pressing. In this case, the method further comprises brushing the surface of the impregnated structured fibers so as to make them partially free, over a predetermined thickness. Other embodiments of the method of manufacturing an elastic sole according to the invention are indicated in the appended claims.

Other characteristics, details and advantages of the invention will emerge from the description given below, without limitation, and with reference to the drawings and the examples.

Figure 1 is a sectional view of an elastic sole according to the present invention.

Figure 2 is a sectional view of an assembly comprising a layer of concrete arranged to be used as a sleeper and an elastic sole according to the present invention.

Figures 3 to 6 illustrate a method of manufacturing an elastic sole according to the invention.

FIG. 7 illustrates a surface brushing step after hot pressing, according to a particular embodiment of the manufacturing method according to the invention.

In the figures, identical or similar elements bear the same references.

Figure 1 illustrates an elastic sole 1 according to the invention arranged to be interposed between a concrete block (not shown) and a ballast (not shown). This elastic sole 1 includes:

- a layer of revulcanized rubber 4,

- a layer of structured fibers 5 partially impregnated in the revulcanized rubber layer 4,

- an interphase 6 comprising impregnated structured fibers 7 and revulcanized rubber 4. According to the present invention, by the terms "partially impregnated in the layer of revulcanized rubber 4", it is meant that the layer of structured fibers 5 has a thickness of free structured fibers 8, that is to say not impregnated in the layer of revulcanized rubber, and a thickness of structured fibers impregnated 7 in the revulcanized rubber 4.

To obtain this elastic sole 1, a sample of devulcanized rubber was taken, originating from tire waste from various vehicles. After having added to this sample at least one adjuvant intended to reactivate the devulcanized rubber, it was shaped into the form of a strip. Said strip of devulcanized rubber was positioned on a lower conveyor belt.

A layer of structured fibers 5 was then superimposed on the layer of devulcanized rubber and two superposed layers were obtained.

Said two superposed layers were conveyed to a press. Said two superimposed layers were hot-pressed at a temperature of 120° C. for 5 minutes. The rubber was then revulcanized during the pressing and an elastic sole 1 according to the present invention was obtained. During the hot pressing, the structured fibers were partially impregnated in said layer of revulcanized rubber 4 forming the interphase 6 revulcanized rubber-fibers.

FIG. 2 illustrates an assembly 10 comprising a layer of concrete 2 arranged to be used as a crosspiece and an elastic sole 1 according to the present invention, an assembly in which said structured fibers 5 are also partially impregnated, over the thickness of fibers structured free 8, in said concrete layer 2, and this before the concrete takes. The crosspiece, formed of the concrete layer 2 and provided with an elastic sole 1 according to the invention, for the dissipation of vibrations, can then be placed on a ballast 3.

In Figures 3 to 6, an elastic sole according to the invention is manufactured according to another embodiment of the invention.

After devulcanization, the mass of recycled rubber, devulcanized, is mixed with additives which promote the essentially mechanical characteristics of the sole. In particular, carbon black can be added, which modifies the hardness, the stiffness and the dissipative power of the vibrations of the sole obtained. The activators/accelerators allow an activation or acceleration of the reactivity of the rubber and therefore of its revulcanization, which will also determine the crosslinking density of the sole.

The devulcanized mass is, after addition of the aforementioned adjuvants, shaped, in particular in the form of a plate 11 having the dimensions of a mold 12. Similarly, a layer of felt 13 made of thermoplastic material, preferably polypropylene, is cut to the size of the mould.

The mold 12 is preheated to a temperature below the melting temperature of the fibers of the felt, preferably between 140 and 170°C, advantageously between 150 and 160°C.

In the preheated mold, the cut felt 13 is first introduced, then the devulcanized rubber plate, shaped 11 is superimposed thereon. Advantageously, the height of the felt 13 and rubber plate 11 assembly is greater than the depth of the cavity of the mold 12. Then the cover 14 of the mold 12 is closed, as shown in FIG. 4, and the assembly is hot-pressed at a pressure preferably greater than 2 MPa, advantageously 6 MPa. This pressure must be sufficient to evacuate the excess material 15 from the mold, as shown in Figure 5.

The vulcanization time depends on the activation/acceleration of the devulcanized rubber mass used. This time can vary between 2 and 15 minutes, advantageously between 3 and 7 minutes.

It is then possible to open the mould, remove the excess material that has not been compressed, and extract from the mold the elastic sole shown in FIG. 6, which has

- a layer of revulcanized rubber 9,

- a layer of structured fibers 13 partially impregnated in the layer of revulcanized rubber 9, and

- An interphase 16 of felt fibers impregnated with revulcanized rubber.

In certain cases, in particular when the devulcanized rubber is of low viscosity and/or the felt of low density, the fibers of the felt are totally embedded in the rubber layer after the hot pressing step, forming a layer of completely impregnated fibers 20 in the layer of revulcanized rubber 9. A surface brushing of the layer of impregnated fibers 20 is then necessary to free some of the fibers over a predetermined thickness. This brushing can be performed as shown in Figure 7, using a circular brush 17 mounted on an axis and adjusted to a predetermined height of a conveyor belt 18. The passage under this brush of the elastic sole coming out of the mold will thus release a thickness of free structured fibers 19, likely to allow the attachment of a layer of concrete thereafter. It is understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made thereto without departing from the scope of the appended claims.

Claims

“CLAIMS”

1. elastic sole (1), arranged in particular to be fixed to a layer of concrete (2) or interposed between a layer of concrete and a ballast (3), characterized in that it consists of a layer of recycled rubber (4, 9), in the revulcanized state after devulcanization, and a layer of structured fibers (5, 13), placed in contact with the rubber layer, the said fibers being partially impregnated in the said rubber layer and having a thickness of free structured fibers (8, 19).

2. Elastic sole according to claim 1, in which the structured fibers have a density of between 150 g/m ² and 800 g/m ² , preferably between 170 and 750 g/m ² , advantageously between 190 and 500 g/m ² .

3. Elastic sole according to claim 1 or 2, wherein the fibers are impregnated to a depth of between 0.5 and 2 mm, preferably between 0.9 and 1 mm in said layer of recycled rubber, in the revulcanized state .

4. Elastic sole according to any one of claims 1 to 3, wherein said layer of recycled rubber in the revulcanized state has a Shore hardness of between 50 and 90, according to the standard measurement model, the durometer.

5. Elastic sole according to any one of claims 1 to 4, wherein said fibers are chosen from the group of natural or synthetic materials, such as polyester, polypropylene, polystyrene, polyethylene, wool, cotton, hemp, coconut fibers.

6. Elastic sole according to any one of claims 1 to 5, wherein said layer of recycled rubber comprises rubber selected from the group of natural or synthetic materials, such as natural polyisoprene, isoprene polymer, polybutadiene, styrene-butadiene copolymer.

7. Elastic sole according to any one of claims 1 to 6, wherein said rubber layer has a tensile strength greater than or equal to 7 MPa, preferably greater than or equal to 8 MPa, advantageously greater than or equal to 9 MPa, even more advantageously equal to 10 MPa.

8. Elastic sole according to any one of claims 1 to 7, wherein said rubber layer has an elongation at break greater than 150%, preferably greater than 200%, or even greater than 250%.

9. Assembly (10) comprising a layer of concrete (2) and an elastic sole (1) as defined in any one of claims 1 to 8, wherein said structured fibers are further partially impregnated on the thickness of free structured fibers (8, 19) in said concrete layer (2).

10. Assembly according to claim 9, in which said fibers are impregnated in the concrete block to a thickness of between 0.3 and 2 mm, preferably between 0.4 and 1.8 mm, more particularly between 0.5 and 1 mm.

11. Method of manufacturing an elastic sole (1) comprising:

- an addition of at least one adjuvant to the devulcanized recycled rubber, - a superposition of a layer of structured fibers (13) and devulcanized recycled rubber (11) with the obtaining of two superimposed layers,

- hot pressing of said two superposed layers at a temperature of between 100 and 180°C for a predetermined time interval with revulcanization of the devulcanized recycled rubber and formation of an elastic sole in which the structured fibers are at least partially impregnated in said layer rubber being revulcanized (9), forming a revulcanized rubber-fiber interphase (16).

12. A method of manufacturing an elastic sole according to claim 11, wherein said at least one adjuvant comprises sulfur, and/or at least one resin and/or at least one reaction activator or accelerator and/or carbon black. carbon.

13. Method of manufacturing an elastic sole according to claim 12, in which said at least one resin is a resin chosen from the group comprising resins having at least one phenol group, at least one aromatic group, at least one styrene group. , and any other resin that can be used with sulfur vulcanized rubber and their combination.

14. Method of manufacturing an elastic sole according to one of claims 12 and 13, wherein said at least one reaction activator is chosen from the group comprising CBS, stearic acid and zinc oxide.

15. Method of manufacturing an elastic sole according to any one of claims 11 to 14, characterized in that, after the addition of at least one aforesaid adjuvant, the mass of devulcanized recycled rubber is shaped and what the fiber layer structured and devulcanized recycled rubber, shaped, are superimposed so as to form said two layers.

16. Method of manufacturing an elastic sole according to any one of claims 11 to 15, characterized in that, during the aforesaid hot pressing, the structured fibers are completely impregnated in the said rubber layer during revulcanization and in that the method further comprises superficial brushing of the impregnated structured fibers so as to make them partially free, over a predetermined thickness (19).

17. Method of manufacturing an elastic sole according to any one of claims 11 to 16, characterized in that the superposition and hot pressing steps are carried out in a mold (12).

18. Method of manufacturing an elastic sole according to any one of claims 11 to 17, characterized in that said devulcanized recycled rubber has a viscosity of less than 70 MU, preferably less than 50 MU, and more particularly less than 40 MU, measured on a Mooney viscometer.