FR2657364A1 - Biodegradable fibrous mat for agricultural and horticultural use - Google Patents

Abstract

The invention relates to the field of fibrous mats. The fibrous mat according to the invention is biodegradable and self-supporting, of the type comprising cellulosic fibres and long fibres with at least two half-corrugations per centimetre of length, consisting of a superposition of laps obtained by carding the mixture of fibres, lapping and needling, the said mat being characterised in that it comprises at least 80% by weight of lignocellulosic fibres coming from wood and at most 20% by weight of the said long fibres, the latter being of animal or vegetable origin. Application to mulching (handling straw), stabilising soils or turfing.

Description

 The present invention relates to a self-supporting biodegradable fibrous mattress for agricultural and horticultural use, that is to say which can be applied to artificial seeding, to mulching or to soil stabilization.

We have already described in the French patent
N 84 04 308, a moldable fibrous mattress intended for hot pressing (for the production of shaped parts in various industries. Such a mattress is essentially composed of 5 to 95% by weight of cellulose fibers and from 0.5 to 10% by weight of long textile fibers, having two half-corrugations per centimeter in length, said mattress further comprising a superposition of fine needled sheets but not rigidly linked to each other, for a final grammage of approximately 2 2 kg / m. In addition, the textile fibers are made of a synthetic material and obtaining molded parts involves either prior gluing of the cellulose fibers by means of a thermosetting resin, or addition during the constitution of the mattress of a certain amount of thermoplastic material.

 While the composition and structure of such a mattress are only intended for die-casting operations with a view to obtaining rigid parts in shape, the Applicant has found that the structure could be applied in a new way, provided that the composition, in order to obtain a flexible fibrous mattress applicable per se to agricultural, horticultural or civil engineering uses such as those briefly recalled above.

For this purpose, the biodegradable fibrous mattress according to the invention comprises at least 80% by weight of lignocellulosic fibers originating from wood and at most 20% by weight of long fibers of animal or vegetable origin. This composition is not glued and it is treated by coating and needling after mixing the fibers, with a view to obtaining a final mattress with a weight of twist of a few hundred g / m2 and not exceeding 2 kg / m2
the lignocellulosic fibers coming from wood result from a thermomechanical type of defibration, while the long fibers, of the half-wavy type as mentioned above, are of animal origin, like wool, or else of origin vegetable, such as sisal, jute, cotton, flax, raffia, bagasse, etc., excluding synthetic substances, to ensure the biodegradable nature of the mattress. For the same reason, the fibers are not bonded by means of a consolidation resin commonly used for products intended for molding applications.

 In general, the manufacture of the mattress according to the invention consists in mixing the fibers and in carding the mixture in the form of a fine sheet of a grammage of 10 to 100 g / m2. Then successive folds of said ply are superimposed to form the mattress, the grammage of which is adjusted between 400 g / m2 and 2000 g / m2 approximately, then a needling of said mattress is carried out. The manufacturing takes place continuously, over a width if necessary adjustable, and over a length which is only limited by the size and the weight of the roller constituted by the winding of the mattress, the mechanical strength of which allows it in particular to be self-supporting.

 In this state, the mattress is for example suitable for mulching: the mattress indeed constitutes a material for the protection of the plants, active for a sufficient duration then disappearing naturally without harm to the environment and being able to provide, in addition to the usual protections against invasion by weeds and against excessive drying of the soil in the vicinity of the plant, new functions such as providing growth factors such as a fertilizer in the vicinity of the plant, or even thermal protection roots.

 A second application concerns the stabilization of soils before revegetation. The soils then targeted are most often sloping, superficial, that is to say devoid of topsoil and lacking capacity to retain water in large quantities: these soils are therefore very exposed to runoff and erosion during heavy precipitation, for example embankments showing the source rock, such as earthworks along communication routes such as roads, motorways, railways or in the vicinity of engineering structures, or even walls quarry or gravel or embankment slopes not stabilized requiring protection before revegetation. The mattress, while ensuring its role, decomposes slowly, constituting a layer of organic matter, the colonization of which by vegetation and, consequently, the stabilization of the soil, are favored.

 Another application consists in the manufacture of a mattress known as a sowing mattress seeded with seeds, optionally provided with adjuvants promoting the germination of the latter and the development of seedlings, such as growth activators, fertilizers etc., said mattress being intended to be placed on surfaces to be sodded. Such surfaces are for example various slopes, namely, motorways, railways, riverbanks, residential terraces, gardens, green spaces, recreation areas, sports etc., either because of rapid development of revegetation is required, either because a support for the roots must be provided when it is lacking. The qualities exploited are the ability of this support to accelerate the germination of seeds by a more significant warming compared to the underlying soil during sunshine, the biodegradability of a 100% natural material, the water retention properties of the fibers and the mechanical resistance of the mattress which can follow the topography of the ground and can be hung on an embankment without tearing.

 To this end, the addition of seeds is carried out during the manufacture of mattresses, for example by means of an adjustable seed hopper or any other suitable device capable of depositing, either in a homogeneous manner or in a predetermined sequence. , seeds and adjuvants. This addition is carried out after the carding operation of the fiber mixture and before the coating operation, or else by interposition of the seeds and additives between two layers coming from two cards and two layers before their mechanical joining by a single and same needling machine. In order to obtain good fixation of the seeds, they may have previously undergone an appropriate treatment with compounds of a biodegradable nature. Naturally, the seeds are not limited to the lawn and can be of various kinds. The addition of fertilizers and other adjuvants is carried out in a similar manner in granular form according to one of the operations mentioned above, and prior to needling, or else in liquid form before drying of the cellulosic fibers and their mixing with the fibers. long.

 By way of example, such a mattress could contain seeds for floral use or for obtaining plants such as vegetables, salads, etc., in substitution for traditional sowing.

 It is understood that the present invention has been described for explanatory purposes but is in no way limiting and that any useful modification may be made to it, in particular in the field of technical equivalences, without going beyond its ambit.

Claims (6)

 1. Self-supporting biodegradable fibrous mattress, of the type comprising cellulosic fibers and long fibers with at least two half-undulations per centimeter in length, consisting of a superposition of layers obtained by carding the mixture of fibers, lapping and needling, characterized by the fact that it comprises at least 80 ffi by weight of lignocellulosic fibers from wood and at most 20 ffi by weight of said long fibers, these being of animal or vegetable origin.  2. Mattress according to claim 1, characterized in that the long fibers consist of wool, sisal, cotton, linen, jute, raffia or bagasse.  3. Mattress according to one of claims 1 or 2, characterized in that it comprises seeds for planting, resulting from the addition of the latter between the carding operation and the topping operation .  4. Mattress according to one of claims 1 or 2, characterized in that it comprises seeds for planting, resulting from the interposition of the latter between two sheets before needling.  5. Mattress according to any one of claims I to 4, characterized in that the cellulosic fibers comprise a fertilizer resulting from its introduction in liquid form before drying and mixing with the long fibers.  6. Mattress according to any one of claims 1 to 4, characterized in that it comprises a fertilizer in granular form, resulting from its introduction before ltoperation has' needling.