Manufacturing process for a bio-based geotextile

Abstract

Method for manufacturing a bio-based geotextile. The present invention relates to a method for manufacturing a geotextile (12), characterized in that it comprises: - supplying a first layer (14) of woven natural fibers; - supplying a second layer (16) of natural fibers; - superimposing the first layer (14) onto a conveyor belt (20), and the second layer (16) onto the first layer (14); and hydrobonding the first layer (14) with the second layer (16) by high-pressure water jet through the first and second layers. Figure for the abstract: Figure 1

Description

Title of the invention: Method for manufacturing a bio-based geotextile

[0001] The present invention relates to a method for manufacturing a geotextile.

[0002] It should be recalled that a geotextile is a permeable textile, intended to be used in contact with soil and / or other material for geotechnical applications, for example drainage, filtration, reinforcement or separation applications.

[0003] Usually, in the prior art, a geotextile is made with synthetic fibers, which give this geotextile high-performance technical characteristics for its use, including good tensile strength, low permeability normal to the plane, and good dynamic perforation.

[0004] It should be noted, however, that synthetic fibers can pose environmental problems.

[0005] In order to address these issues, it is possible to consider a geotextile made of natural fibers, but the state of the art does not include a process for producing such geotextiles made of natural fibers which have performance as good as a geotextile made of synthetic fibers.

[0006] The invention aims in particular to remedy this drawback, by proposing a method for manufacturing a bio-based geotextile, the performance of which is at least similar to that of a synthetic geotextile.

[0007] To this end, the invention relates in particular to a method for manufacturing a geotextile, characterized in that it comprises:

[0008] - the supply of a first layer of a woven fabric made of natural fibers,

[0009] - the supply of a second layer of natural fibers,

[0010] - the superimposition of the first layer on a conveyor belt, and of the second layer on top of the first layer,

[0011] - the hydrobonding of the first layer with the second layer, by spraying water at high pressure through the first and second layers.

[0012] The invention is the result of more than two years of work on test facilities and with recognized analytical laboratories to achieve this level of performance sought.

[0013] The process according to the invention uses the properties of pectin contained in natural fibers to obtain the desired performance for the geotextile. In particular, the inventors have established that hydrobonding is especially effective when it utilizes these properties of pectin.

[0014] Advantageously, the process is optimized by carrying out the hydrobinding under the best conditions for preserving the pectin. In particular, these conditions correspond to technical conditions of water pressure and quality and natural fiber characteristics corresponding to a specific agricultural technical approach.

[0015] A manufacturing process according to the invention may thus have one or more of the following optional characteristics, taken alone or in any technically feasible combinations.

[0016] - The manufacturing process includes supplying two first layers of woven, arranged on either side of the second layer, then the hydrobonding of these three layers.

[0017] - The manufacturing process includes a step for regulating water quality used for hydrolinking, during which temperature, pH, purity and / or turbidity of the water are regulated.

[0018] - Water quality regulation includes at least one of the following regulations the following: - temperature regulation between 25 and 35 °C; - pH regulation between 6.5 and 7.5; - purity regulation to present less than 1000 units / ml of bacteria, less than 2 mg / l of suspended solids, and / or no particles greater than 1 Opm; - turbidity regulation less than 2 NTU.

[0019] - Water quality regulation includes both the regulation of the temperature, pH, purity and turbidity of the water.

[0020] - The first layer has a basis weight between 70 and 1000 g / m2, and the second layer has a weight between 70 and 1000 g / m2.

[0021] - The first layer is made of hemp, flax and / or jute fibers, and the the second layer is made of hemp, flax and / or jute fibers.

[0022] - The manufacturing process includes a step of treating the geotextile, by impregnation with natural materials, such as Chitosan or any natural waterproofing agent.

[0023] Various aspects and advantages of the invention will be highlighted in the following description, given solely by way of example and with reference to the accompanying figures, among which:

[0024] [Fig.1] Fig.1 is a schematic longitudinal cross-sectional view of a manufacturing device for implementing the manufacturing process according to an example embodiment of the invention;

[0025] [Fig.2] Fig.2 is a top view of the geotextile produced by the device of the [Fig.l].

[0026] Figure [Fig. 1] shows a manufacturing device 10 according to an example of an embodiment of the invention.

[0027] The manufacturing device 10 is intended for the implementation of a manufacturing process for a geotextile 12 shown in [Fig.2].

[0028] The geotextile 12 is formed by a first layer 14 of a woven natural fibers and a second layer 16 of a non-woven natural fibers entangled with the first layer 14.

[0029] Preferably, the non-woven fabric 16 has a basis weight of between 70 and 1000 g / m2.

[0030] Advantageously, the natural fibers forming the non-woven fabric 16 are chosen from hemp, flax and / or jute fibers, or any other conceivable natural fiber, or any combination of such fibers.

[0031] The woven material 14 forms, for example, a net, produced by any known weaving process. The net has a woven or knitted mesh, the geometry of which varies depending on the application. Preferably, the woven material 14 has a basis weight of between 70 and 1000 g / m².

[0032] Advantageously, the natural fibers forming the woven fabric 14 are chosen from hemp, flax and / or jute fibers, or any other conceivable natural fiber, or any combination of such fibers.

[0033] It should be noted that, since the geotextile is made up solely of natural fibers, this geotextile forms a bio-based material.

[0034] The manufacturing device 10 includes a conveying device 18, intended to receive the first 14 and second 16 layers, stacked one on top of the other. The conveyor includes a conveying belt 20, on which the first 14 and second 16 layers are stacked.

[0035] The conveyor belt 20 has, for example, a width greater than 4 meters, to allow the production of a geotextile belt with a width of approximately 4 meters.

[0036] Preferably, the first layer 14 is arranged against the conveyor belt 20, and the second layer 16 is arranged on the first layer 14.

[0037] In the example described, the conveying device 18 is a transport roller.

[0038] Preferably, the conveying device 18 includes suction means, creating suction on the first 14 and second 16 layers, in order to hold them against each other, and against the conveyor 18. For this purpose, the conveying device 18 includes a plurality of suction channels 22 opening at the level of the conveying belt 20. The suction channels 22 are connected to a suction device 24 arranged, for example, under the conveying device 18.

[0039] For example, the suction channels 22 open under the conveyor belt 20, the conveyor belt 20 being porous to allow the suction of the first 14 and second 16 layers.

[0040] It will be noted that, given the mesh of the first layer 14, the suction generally has no effect on this first layer 14. However, since the first layer 14 is arranged under the second layer 16, this first layer 14 remains pressed against the conveyor belt 20 by the second layer 16, which is, in turn, suctioned.

[0041] The manufacturing device 10 further comprises at least one nozzle 26 directed towards the conveyor belt 20, configured to project a high-pressure water jet towards this conveyor belt 20.

[0042] For example, the nozzle 26 is configured to project a jet of water with a pressure between 50 and 300 bar.

[0043] It should be noted that the conveyor belt 20 is sufficiently porous to allow the water jet to pass through.

[0044] Advantageously, the manufacturing device 10 comprises a plurality of nozzles 26 aligned over the width of the conveyor belt 20, so as to form together a high-pressure water veil 28.

[0045] The nozzles 26 are preferably carried by a common support 30.

[0046] Advantageously, the support 30 is height-adjustable, in order to allow adjustment of the distance between the nozzles 26 and the fiber layers 14 and 16. Adjusting the height allows optimizing the quality of the hydrobonding according to the products to be hydrobonded (surface mass, type of materials) and energy consumption.

[0047] The nozzles 26 are connected to at least one high-pressure pump 32, which supplies these nozzles 26 with high-pressure water.

[0048] The nozzles 26 allow for hydrobonding of the first 14 and second 16 layers of fibers.

[0049] The first layer 14 is arranged, in the form of a net, upstream of the nozzles 26, and the second layer 16 is arranged, preferably in the form of free fibers, on this first layer 14.

[0050] When the assembly of the first 14 and second 16 layers passes, driven by the conveying device 18, through the veil of pressurized water, the fibers of the second layer 16 are hydrolinked under the effect of the pressurized water, becoming entangled with the mesh of the first layer 14, which thus forms a structural part of the geotextile 12.

[0051] To ensure optimal hydrobonding efficiency, this process is carried out under optimal conditions for preserving the pectin contained in the natural fibers. Specifically, these conditions correspond to technical requirements regarding water pressure and quality, as well as natural fiber characteristics, specific to a particular agricultural production method. This results in satisfactory performance for the geotextile.

[0052] For this purpose, the manufacturing device 10 according to the invention includes a device 34 for regulating the water quality under the said optimal conditions for preserving pectin.

[0053] The control device 34 is configured to perform at least one of the following controls, and preferably all of the following controls:

[0054] - temperature regulation,

[0055] - pH regulation,

[0056] - a purity regulation,

[0057] - turbidity regulation.

[0058] The temperature is preferably regulated between 25 and 35°C.

[0059] Temperature regulation is achieved by supplying warm water.

[0060] The pH is preferably regulated between 6.5 and 7.5...

[0061] pH regulation is achieved by basic or acid titration.

[0062] Purity is preferably regulated to remove bacteria to obtain less than 1000 units / ml, and to remove particles smaller than 10 µm, for example by bag filtration. It is also preferably ensured that there is less than 2 mg / l of suspended solids, and that there is an absence of fungi, yeasts, molds, or algae.

[0063] Turbidity is preferably regulated to be less than 2 NTU, for example by turbidity analysis by turbidimeter and influenced by pH, suspended matter, therefore flocculant and coagulant dosages.

[0064] Water is considered to be of optimal quality when it is regulated according to all these conditions.

[0065] It is this water of optimal quality which is supplied to the pumps 32 and then projected by the nozzles 26.

[0066] The fibers, thus hydrolinked by this water whose quality allows for the preservation of pectin, enable the production of a geotextile of optimal quality.

[0067] It thus appears that the geotextile 12 produced according to the invention has a tensile strength, as defined by the standard (NF EN ISO 13319), of between 0.5 and 10kN / m.

[0068] The geotextile 12 produced according to the invention also has a normal permeability to the plane, as defined by the standard (NF EN ISO 11058), of less than 0.09 m / s.

[0069] The geotextile 12 produced according to the invention also has a dynamic perforation, as defined by the standard (NF EN ISO 10319), of less than 50 mm.

[0070] Finally, the geotextile 12 produced according to the invention has a lifespan of between 12 and 60 months.

[0071] The manufacturing process according to the invention will now be described.

[0072] The process includes a step of supplying the first layer 14 of woven material. For this purpose, natural fibers are woven, in particular in the form of a net, using a weaving process known per se.

[0073] The first layer 14 is arranged on the conveyor belt 20.

[0074] The process includes a step of supplying the second layer 16. This second layer 16 is supplied in the form of free fibers, which are arranged on the first layer 14.

[0075] The assembly of these first 14 and second 16 layers is held on the conveyor belt 20 by means of the suction means 22, 24.

[0076] The assembly of these first 14 and second 16 layers is conveyed by the conveyor belt 20 until it passes under the nozzles 26, which together project a veil of high-pressure water over the entire width of this assembly.

[0077] Water under high pressure is projected towards the conveyor belt 20, passing through the second layer 16, then the first layer 14, thus creating a hydrolinking of the fibers of the first 14 and second 16 layers, which are thus entangled to form the geotextile 12.

[0078] The fibers of the second layer 16, thus linked together, also form a non-woven, entangled with the woven 14.

[0079] The process includes, upstream of this hydrobonding, the treatment of the water to be sprayed, under conditions of optimal preservation of the pectin contained in the fibers. It appears, in fact, that hydrobonding is particularly effective when it utilizes the properties of pectin.

[0080] The process then involves recovering the geotextile 12 thus formed, at the outlet of the conveyor belt 20.

[0081] Advantageously, the process includes a step of treating the geotextile by impregnating it with natural materials, such as chitosan or any other waterproofing agent. This treatment increases the lifespan of the geotextile.

[0082] It should be noted that the invention is not limited to the embodiment described above.

[0083] In particular, in one variant, the first layer 14 is superimposed on the second layer 16, so that the stream of pressurized water passes through the first layer before the second layer.

[0084] In another variant, the geotextile is manufactured by superimposing three layers, namely two first layers 14 of woven material on either side of a second layer 16. Hydrolinking then allows these three layers to be intertwined.

Claims

Demands

1. A method for manufacturing a geotextile (12), characterized in that it comprises: - the provision of a first layer (14) of a woven natural fiber, - the provision of a second layer (16) of natural fibers, - the superimposition of the first layer (14) on a conveyor belt (20), and of the second layer (16) on the first layer (14), - the hydrobonding of the first layer (14) with the second layer (16), by high-pressure water spraying through the first and second layers.

2. A manufacturing method according to claim 1, comprising supplying two first layers (14) of woven material, arranged on either side of the second layer (16), and then hydrobonding these three layers.

3. A manufacturing process according to claim 1 or 2, comprising a step of regulating the quality of the water used for hydrolinking, during which the temperature, pH, purity and / or turbidity of the water are regulated.

4. A manufacturing process according to claim 3, wherein the water quality control comprises at least one of the following controls: - temperature control between 25 and 35 °C; - pH control between 6.5 and 7.5; - purity control to present less than 1000 units / ml of bacteria, less than 2 mg / l of suspended solids, and / or no particles greater than 1 OPM; - turbidity less than 2 NTU.

5. A manufacturing method according to claim 3 or 4, wherein the regulation of water quality includes both the regulation of temperature, pH, purity and turbidity of the water.

6. A manufacturing method according to any one of the preceding claims, wherein the first layer (14) has a basis weight of between 70 and 1000 g / m2, and the second layer (16) has a basis weight of between 70 and 1000 g / m2.

7. A manufacturing method according to any one of the preceding claims, wherein the first layer (14) is made of hemp, flax and / or jute fibers, and the second layer (16) is made of hemp, flax and / or jute fibers.

8. A manufacturing process according to any one of the preceding claims, comprising a step of treating the geotextile by impregnation with natural materials, such as Chitosan or any natural waterproofing agent.

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