Biodegradable mulch with high mechanical resistance

Abstract

A biodegradable horticultural mulch film (1) consisting of an arrangement of non-woven natural fibers (2) forming a longitudinal plane, said arrangement comprising hair (3) and flax fibers (4) mixed and assembled into a consolidated non-woven arrangement, the flax fibers constituting a mass percentage of between 35 and 80% of the total fibers, and more preferably a mass percentage of between 45 and 55% of all the film's fibers. FIGURE 2

Description

Title of the invention: Biodegradable mulch with high mechanical resistance technical field

[0001] The present invention relates to a horticultural mulch film made up of an arrangement of non-woven fibers. Previous technique

[0002] Many types of mulch are used in horticulture to facilitate plant growth, protect plants, and allow for better control of soil moisture and structure. Most mulches use non-biodegradable synthetic materials.

[0003] For example, document FR2768018 describes a horticultural mulch mat, its industrial manufacturing process, and its use in flowerbeds. The mulch mat is made of fragments of various materials, including wood derivatives, synthetic materials, minerals, and adhesives, on a water-permeable fabric. The invention also relates to the process for manufacturing the mulch mat, which consists of selecting material fragments based on their physical, mechanical, and aesthetic characteristics, impregnating them with adhesive and dye, and then depositing them on a water-permeable fabric, which is itself placed on a plastic film to which the adhesive does not adhere. This mulch is used to surround floral arrangements, decorations, and their borders. This type of film is complex to manufacture and is not biodegradable.

[0004] Other mulches use biodegradable materials. For example, document EP3469888 describes a biodegradable mulch film comprising a base substrate made of paper onto which a coating is applied.

[0005] Document WO2006076057 describes a mulch made of biodegradable natural fibers such as hair, animal fur, coconut fiber, cotton fiber, corn fiber, or others. The document describes, among other things, a mulch comprising hair, animal fur, and one or more natural fibers such as coconut, cotton, corn, or others. However, the mechanical strength characteristics of this type of mulch are limited.

[0006] The document "Test of a needle-punched sheep's wool mulch," by Florent MORNARD, published on December 30, 2020, describes a test carried out on a single-fiber sheep's wool mulch. This mulch, made solely from animal-derived fibers, has room for improvement in its ecological profile. Furthermore, the limited mechanical properties of this single-fiber mulch mean that it is susceptible to cracking or breaking when handled.

[0007] Document WO2006076057 describes a biodegradable mat made entirely of natural fibers intended for use in the germination, growth enhancement, and propagation of plants and trees and the suppression of weed growth. The mat comprises a generally flat layer of at least one or a combination of natural fibers including human hair, animal hair, coconut fiber, seaweed, kelp, cotton, corn silk, and peat moss, and alternatively may incorporate a plurality of synthetic fibers.

[0008] Mulches made from natural fibers such as hemp are also known. The drawback of these products is that, as hemp gradually decomposes, it depletes the soil of nitrogen, thus depriving any plants of essential nutrients for their growth.

[0009] To overcome the various disadvantages previously mentioned (in particular mechanical strength and the impact on the quantity of nitrogen available), the invention provides various technical means. Summary of the invention

[0010] First of all, a first object of the invention is to enable the implementation of low-cost mulching by recovering and recycling hair clippings from hair salons.

[0011] Another objective of the invention is to provide mulch comprising natural biodegradable materials.

[0012] Another objective of the invention is to provide a mulch whose mechanical characteristics, and in particular tensile strength, are optimal.

[0013] Another objective of the invention is to provide a mulch whose mechanical and visual characteristics, in particular on the surface, are homogeneous and constant.

[0014] Yet another objective of the invention is to provide a mulch that is easy to store before being placed in the natural environment and respects the surrounding natural environment.

[0015] To this end, the invention provides for a biodegradable horticultural mulch film made up of an arrangement of non-woven natural fibers forming a longitudinal plane, said arrangement comprising hair and elementary flax fibers mixed and assembled in a consolidated non-woven arrangement, the elementary flax fibers constituting a mass percentage between 35 and 80% of the total fibers, and more preferably a mass percentage between 45 and 55% of all the fibers of the film.

[0016] The use of two types of complementary fibers, preferably without any other material, constituent or additive, makes it possible to obtain the mechanical properties considered significantly improved compared to a film made with only one type of fiber. Furthermore, the planned mass proportions allow for further optimization of mechanical performance. Finally, combining and intertwining these two types of fibers induces a dual support effect: that generated by consolidation and that of micro-interlocks between the fibers.

[0017] Furthermore, this film exhibits mechanical properties four to ten times greater than those of products made from a hair-wool blend. At an equivalent basis weight, this film exhibits mechanical properties nine to sixteen times greater compared to blends with other plant fibers such as cotton or hemp.

[0018] This makes it possible to obtain a geotextile made of biodegradable natural fibers, ideal for mechanized implementation, in particular for anti-erosion and mulching applications over long lengths of soil.

[0019] Advantageously, the elementary flax fibers have a length between 30 and 60 mm and more preferably between 40 and 50 mm.

[0020] Also advantageously, flax fibers have a diameter between 10 and 40 microns and more preferably between 15 and 25 microns, and even more preferably 20 microns.

[0021] According to an advantageous embodiment, the biodegradable mulch film consists solely of hair fibers and elementary flax fibers.

[0022] This embodiment, without additives or supplements or reagents or other materials or support layers, makes it possible to obtain a 100% natural, ecological, biodegradable product without residue.

[0023] According to an advantageous embodiment, the consolidation of the film is achieved by the presence of a plurality of bridges crossing at least a part of the fiber layers, said bridges being distributed over the entire surface of the mulch film.

[0024] Advantageously, the through bridges are made by needle tying or hydro-tying or by air jets.

[0025] The filaments arranged substantially transversely are distributed substantially uniformly over the surface of the film and form a mechanical bonding means between the filaments oriented substantially longitudinally. The film thus exhibits particularly advantageous mechanical strength characteristics.

[0026] Advantageously, the film is wound to form a roll facilitating storage and unrollable for placement on a horticultural surface to be covered.

[0027] The resulting non-woven mulch can have a weight ranging from 300 to 1500 g / m2, preferably between 450 and 1000 g / m2 with thicknesses of 5 to 12 mm.

[0028] The mulch can be supplied in roll form, with for example a width ranging from 0.5 to 3.6 meters.

[0029] This type of format is particularly suitable for mulching, and allows for good compromise between the ease of storage by rolling and the advantageous characteristics of water retention and protection against germination. Brief description of the drawings

[0030] All implementation details are given in the following description, supplemented by Figures 1 to 8, presented solely for the purpose of non-limiting examples, and in which: Fig. 1

[0031] [Fig.1] [Fig.1] is a schematic top view representation of consolidated non-woven biodegradable films of hair and flax; Fig. 2

[0032] [Fig.2] [Fig.2] is a schematic cross-section in the transverse plane of the width of an example of a biodegradable film made from a consolidated non-woven arrangement of hair and flax; Fig.3

[0033] [Fig.3] [Fig.3] is a schematic cross-section in the transverse plane of the height of an example of a biodegradable film made from a consolidated non-woven arrangement of hair and flax; Fig. 4

[0034] [Fig.4] [Fig.4] is a schematic representation illustrating a phase of consumption description of an example of a non-woven arrangement of hair and flax by needle punching; Fig. 5

[0035] [Fig. 5] [Fig. 5] illustrates a summary table showing the results of tests for compare the mechanical properties of several examples of biodegradable non-woven films consolidated with different types and weights of fibers combined with hair; Fig. 6

[0036] [Fig.6] [Fig.6] illustrates a summary table showing the results of tests for compare the mechanical properties of several examples of biodegradable non-woven films consolidated with different types of fibers; Fig. 7

[0037] [Fig.7] [Fig.7] illustrates a summary table showing the results of tests for compare the mechanical properties of biodegradable non-woven films consolidated from hair and flax with different proportions of fibers; Fig. 8

[0038] [Fig.8] Fig.8 schematically illustrates the different phases during the cotton- nisation of flax, with, from left to right of the figure, an uncut stem, a cut stem with its constituents, a technical fiber and a resulting elementary fiber. Description of implementation methods Definitions

[0039] An unconsolidated nonwoven fabric consists of a collection of fibers simply arranged together in a loose fashion, without being bonded to each other. The strength of an unconsolidated nonwoven fabric depends on the strength and resistance of the fibers themselves and on the forces that bind these fibers together.

[0040] A consolidated nonwoven film is defined as an assembly consisting of a plurality of layers of filaments or fibers held together by a plurality of bridges crossing at least a portion of the layers. The bridges are formed by fibers oriented transversely to the principal plane of the film and interwoven with layers of fibers oriented in the principal plane of the film.

[0041] Several consolidation processes can be used, such as needle punching or hydro-bonding or by air jets.

[0042] Needle punching refers to a consolidation process which consists of mechanically interlocking one or more layers of fibers or filaments using multiple hook needles.

[0043] Hydrobonding or water interlocking refers to a mechanical assembly process by consolidation using a plurality of high-pressure water jets passing through a film to be consolidated.

[0044] Before consolidating the fibers or filaments, a fiber opening step is preferably carried out.

[0045] The term "opening" refers to a mechanical process consisting of breaking down compressed layers or clumps of fibers into small tufts to facilitate mixing. At the inlet of the opening machine, clumps of flax fibers and unmixed hair are transformed into a homogeneous mixture of flax fibers and hair. The opening machine is fed with raw flax fibers and hair filaments.

[0046] Double-action bonding consolidation is understood to be a method of consolidating a film containing flaked fibers such as hair.

[0047] By "cottonized" is meant the process of separating flax stems (classically with a diameter of 2 to 4 mm) first into technical fibers and then into elementary fibers with a much finer diameter of the order of 10 to 40 µm, as illustrated in [Fig. 8]. This operation can be carried out mechanically (the most common), chemically, or enzymatically.

[0048] The term "biodegradable horticultural mulch film" means a soil mulch film specifically designed and adapted for all types of crops (vegetables, fruits, trees, shrubs, flowers, plants or all types of vegetation), or for soil maintenance or for earthworks.

[0049] Figure 1 illustrates an example of a biodegradable film 1. In this example, two strips 6 of film 1 are laid on the ground and crops 10 are distributed over the surface of the strips. To allow for the establishment and growth of the crops, the strips have a plurality of holes made either during manufacturing or during planting.

[0050] The biodegradable films 1 are made using natural fibers 2 consisting of hair 3 and elementary flax fibers 4. The natural fibers used are of all lengths, including short hair. Figures 2 and 3 schematically illustrate examples of the implementation of films 1 using these fibers.

[0051] Figure 2 shows an example of a film 1 in cross-section in the width direction. As illustrated, the film comprises a plurality of natural fibers 2, essentially hair 3 and elementary flax fibers 4 intertwined by means of a shaping with consolidation.

[0052] First, before manufacturing the mulch film, the flax fibers used are preferably cottonized and cut into regular lengths of 30 to 60 mm, ideally 40 to 50 mm. The diameter of the cottonized fibers is preferably 20 µm. This cottonization phase allows the production of elementary flax fibers.

[0053] The film production process comprises two main phases. The first phase consists of creating a homogeneous layer with a mixture of hair and flax in the desired mass proportions. The second phase, known as the consolidation phase, consolidates the layer(s) to obtain a film with excellent mechanical properties.

[0054] To carry out the first phase, the hair is mixed with the flax, with the flax content being greater than 35% of the total mixture.

[0055] The proportions used range from 20 to 65% hair and preferably from 45 to 55% hair. The remainder being flax fiber.

[0056] Hair and flax fibers are dispersed and mixed to obtain a homogeneous material.

[0057] The material is coated and then needled in order to create mechanical bonds, without the addition of binders.

[0058] The hair and flax fibers are placed in loader-weighers that allow the fibers to be weighed to obtain the desired mass proportions of each type of fiber (i.e., the percentage of hair and the percentage of flax fiber relative to the total weight of hair and flax fibers). The hair then falls onto a conveyor belt where it is moistened to facilitate cohesion between the fibers, followed by the flax fibers. All the fibers (hair and flax) then pass through an opener that opens and mixes the fibers. The mixture is advantageously transported by air where a magnet helps to Any metallic objects that may remain in the fibers are removed before the fibers are passed through a finer opener to more thoroughly blend the mixture. The resulting fibers are then transported either to a carding and layering machine or, more advantageously, directly by air to the layering machine. The layering machine creates a homogeneous sheet of the hair and flax blend in the proportions initially chosen.

[0059] During the consolidation phase, the layered fibers are then consolidated using a multitude of cross-bridges 5 distributed across the entire surface of the film. A needle-punching process is preferably used to create these cross-bridges. Figure 4 schematically illustrates an example of a needle-punching operation. This is a mechanical assembly process for consolidating a non-woven film already formed by layering. A plurality of needles 7 equipped with hooks 8 are arranged transversely to the main plane or the surface of the fiber arrangement and move back and forth through the film. Some of the flax and / or hair fibers are caught by the hooks 8 and carried along with the transverse movement of the needles 7, thus creating an entanglement with the longitudinally oriented flax or hair fibers.The needles are arranged to form a needle-punching surface, with a density adapted to the product to be manufactured. For example, some successful tests were carried out with a first sheet of 3660 needles per meter, and a second sheet of 7000 needles per meter with a needle-punching density of 110 strokes / cm². Each phase advantageously involves several back-and-forth movements of the needles.

[0060] Finally, the needles can be arranged on one side only, or in opposition, on both sides of the film to be consolidated. Figure 3 schematically illustrates an example of film 1 obtained by consolidation with opposing needles. Figure 3 shows film 1 in cross-section along its height. The hair 3 and flax fibers 4 are generally oriented lengthwise along the film. The bridges 5, formed by the hair and / or flax fibers, are arranged vertically.

[0061] Other processes can also be used, such as hydrobonding or consolidation by high-pressure water jets.

[0062] According to yet another advantageous embodiment, the biodegradable film comprises a mixture of hair fibers and flax fibers previously dispersed and mixed to constitute batches of at least 10 kg of dispersed and mixed fibers so as to form a random set of heterogeneous fibers before shaping them into a film.

[0063] For example, in tests, the hair fibers used came from hair contained in bags of lm3, or approximately 100 kg, representing about 125,000 haircuts with varying content and a reliable and recurring source of homogeneity. The hair to be recycled most often comes from hair salons. The Grouping the recovered hair allows the use of hair from multiple people, with very varied characteristics, particularly in terms of color, and allows for a mulch with more uniform color characteristics and mechanical resistance. Comparative mechanical resistance tests

[0064] The table in [Fig. 5] presents the results of comparative tests between a hair-flax mulch according to the invention and a known hair-wool mulch for different weights. It can be seen that the maximum uniaxial tensile strength is four to ten times greater with the hair-flax mulch.

[0065] Figures 5, 6 and 7 present comparative tables from tests carried out with mulches according to the invention.

[0066] The table in [Fig. 6] presents the results of comparative tests between a hair-flax mulch according to the invention and various hair-plant fiber mulches for different fibers (cotton, hemp, conventional flax). It can be seen that the maximum uniaxial tensile strength is nine to sixteen times greater compared to mixtures with other plant fibers (cotton, hemp) and four times greater with the conventional (unprepared) hair-flax mulch of the same basis weight.

[0067] The table in [Fig. 7] presents the results of comparative tests between a hair-flax mulch with a proportion of 65% hair and 35% flax and a hair-flax mulch with a proportion of 50% hair and 50% flax. It can be seen that the maximum uniaxial tensile strength is three times greater with the mulch having a higher proportion of flax.

[0068] The table below presents a summary of tests carried out with several mixtures and weights in order to demonstrate the gains in mechanical strength of the newly designed mulch: Biodegradable Mulch Mix Weight (g / m2) UTS (N / 5cm) Wool-Hair 450 2.8 600 5.0 1000 18.9 Hemp-Hair 450 4.9 600 6.2 1000 15.3 Cotton-Hair 600 3.4 Classic Linen Hair 450 8.2 600 13.7 1000 20.8 Hair 65% - Prepared Linen 35% 450 10.2 Hair 50% - Prepared Linen 50% 450 30.7 600 55.0 1000 83.1

[0069] These tests show that a level of mechanical resistance to breakage greater than 20 N / 5 cm, and preferably greater than 30 N / 5 cm, and even more preferably greater than 50 N / 5 cm, can be achieved with the newly designed mulch. It is further observed that other fiber mixtures require higher basis weights than the mixture with prepared flax to obtain good mechanical strength.

[0070] This increase in maximum tensile strength is particularly advantageous for mechanical resistance in the longitudinal direction, making it possible to handle long films without risk of accidental breakage. These high-strength properties are particularly advantageous in applications where long films must be handled and frequently moved by pulling them along the ground, under high mechanical stress.

[0071] This makes it possible to obtain a geotextile made of biodegradable natural fibers, ideal for mechanized implementation, in particular for anti-erosion and mulching applications over long lengths of soil. List of reference signs

[0072] 1. Mulch film 2. Non-woven natural fibers 3. Hair 4. Lin 5. Bridges 6. Widths 7. Needle 8. Crochet 9. 10. Culture

Claims

Demands

1. Biodegradable horticultural mulch film (1) consisting of an arrangement of non-woven natural fibers (2) forming a longitudinal plane, said arrangement comprising hair (3) and elementary flax fibers (4) mixed and assembled into a consolidated non-woven arrangement, the elementary flax fibers being cottonized and constituting a mass percentage of between 35 and 80% of the total fibers, and more preferably a mass percentage of between 45 and 55% of all the film fibers.

2. Biodegradable mulch film according to claim 1, wherein the elementary flax fibers have a length between 30 and 60 mm and more preferably between 40 and 50 mm.

3. Biodegradable mulch film according to any one of claims 1 or 2, wherein the elementary flax fibers have a diameter between 10 and 40 microns and more preferably between 15 and 25 microns, and even more preferably 20 microns.

4. Biodegradable mulch film according to any one of claims 1 to 3, consisting solely of hair fibers and elementary flax fibers.

5. Biodegradable mulch film according to any one of claims 1 to 4, wherein the consolidation of the film is achieved by the presence of a plurality of bridges (5) crossing at least a part of the fiber layers, said bridges being distributed over the whole surface of the mulch film.

6. Biodegradable mulch film according to claim 5, wherein the crossing bridges (5) are made by needle punching or hydro-bonding or by air jets.

7. Biodegradable mulch film according to any one of claims 1 to 6, rolled up to form a roll facilitating storage and unrollable for placement on a horticultural surface to be covered.

8. Biodegradable mulch film according to any one of claims 1 to 7, formed in strips (6).