Compacted material made from tree leaves

Abstract

Commercially available sawdust-based agglomerates / compressions are brittle and often require the use of an adhesive to act as a binder and improve their strength and moisture resistance. The use of these adhesives raises several questions regarding their environmental impact: the polluting manufacturing process, the petrochemical-derived composition, the emission of volatile organic compounds, the end-of-life management of the material, and its recycling. The materials of the invention address all of the aforementioned drawbacks. These 100% bio-based materials are obtained by hot compression of tree leaf powder, either alone or mixed with sawdust, to produce panels, bricks, or any other thermoformed object using, for example, a hydraulic press or a heated extruder.The materials of the invention exhibit a significant improvement in their mechanical properties and also offer an environmentally friendly alternative to products currently on the market. The invention also relates to the process for obtaining and the products obtained from these materials.

Description

Title of the invention: Compacted material based on tree leaves

[0001] Commercially available sawdust-based agglomerates / compressions are brittle and often require the use of an adhesive as a binder to improve their strength and moisture resistance. The use of these adhesives raises several questions regarding their environmental impact: polluting manufacturing processes, petrochemical-derived composition, emission of volatile organic compounds, end-of-life management of the material, and recycling...

[0002] The materials of the invention overcome all the drawbacks described above. These materials, 100% bio-based, are obtained by hot compression of tree leaf powder, alone or mixed with sawdust, for the production of panels, bricks, or any other thermoformed object using, for example, a hydraulic press or a heated extruder. The materials of the invention exhibit a significant improvement in their mechanical properties and also offer an environmentally friendly alternative to products currently on the market. The invention also relates to products obtained from these materials.

[0003] technical field

[0004] The invention relates to the field of design, structural and aesthetic materials used for design, for the manufacture of furniture and objects; for interior architecture, for the manufacture of panels and bricks; as well as for the field of fuels, for the manufacture, for example, of wood chips, bricks and heating pellets.

[0005] Conventional agglomerated materials made from agglomerated sawdust have a number of drawbacks. Several tree species can be used for this purpose. However, some tree species are difficult to compact. Indeed, hot compaction of hardwood sawdust alone does not yield satisfactory results. They are brittle and require the use of a binder, an adhesive, in proportions of up to 15%, to give the material strength and moisture resistance. Most often, these adhesives are derived from petrochemicals and raise a number of questions regarding their environmental impact: the polluting manufacturing process, the petrochemical composition, volatile chemical compounds, the end-of-life of the material, and recycling.

[0006] Another drawback is the depletion of wood resources due to excessive logging. Deforestation is a major global environmental and political issue. Furthermore, the long regeneration cycle of the raw material, approximately 20 to 30 years for a A major problem arises when a tree can reach maturity to be harvested for its timber.

[0007] Previous technique

[0008] Every year, French cities generate tons of green waste, of which fallen leaves represent a significant portion. According to ADEME (the French Agency for Ecological Transition), urban green spaces produce an average of 8 million tons of green waste per year, a large part of which consists of fallen leaves. This waste is often collected and transported to treatment centers, generating significant logistical and environmental costs.

[0009] Dead leaves, which are under-exploited to date, represent a valuable resource that offers many ecological and practical advantages.

[0010] First, their regeneration cycle is extremely short. It only takes one year for new leaves to fall and be ready for harvesting. This is quite remarkable in the field of materials, where raw material regeneration cycles are generally much longer. Furthermore, harvesting fallen leaves does not require cutting down trees, thus preserving forests and biodiversity by using an already available resource.

[0011] Furthermore, as described previously, leaf collection systems already exist. Leaves are currently collected by municipal services, meaning there is no need to create a new collection network. It is sufficient to establish partnerships or sign contracts with companies already handling this task. This greatly simplifies logistics and reduces associated costs.

[0012] Finally, fallen leaves often clutter public spaces, create practical nuisances, and make roads slippery. By transforming them into a useful material, an ecological alternative for their management is offered, beyond simply considering them as waste. Cities would thus benefit from a sustainable and innovative solution, reducing the volume of waste to be processed and making use of an abundant natural resource.

[0013] We are aware of patent application FR 488941 of 1918 filed by Karen Bramson, which suggests creating agglomerates of dead leaves. However, no example of implementation is presented therein, and since then, to our knowledge, no industrial implementation has made it possible to utilize leaves, preferably dead ones to avoid any impact on tree growth, as a raw material for transforming them into high value-added materials. Description of the invention

[0015] As previously explained, commercially available sawdust-based agglomerates / compressions are brittle and often require the use of an adhesive to act as a binder and improve their strength and moisture resistance. The use of these adhesives raises several questions regarding their environmental impact: the polluting manufacturing process, the petrochemical-derived composition, the emission of volatile organic compounds, the end-of-life management of the material, and its recycling.

[0016] The applicants have conducted numerous tests and demonstrated that when a 100% bio-based composition, comprising tree leaf powder, alone or mixed with sawdust, is hot-compacted / compressed between 80°C and 130°C, for example using a hydraulic press or a heated extruder, to produce panels, bricks, or any other thermo-compressed objects, the resulting materials exhibit a significant improvement in their mechanical properties. This invention thus offers an environmentally friendly alternative to products currently on the market and overcomes all the drawbacks described above.

[0017] Summary of the invention

[0018] Commercially available sawdust-based agglomerates / compressions are brittle and often require the use of an adhesive to act as a binder and improve their strength and moisture resistance. The use of these adhesives raises several questions regarding their environmental impact: the polluting manufacturing process, the petrochemical-derived composition, the emission of volatile organic compounds, the end-of-life management of the material, and its recycling.

[0019] The materials of the invention overcome all the drawbacks described above. These materials, 100% bio-based, are obtained by hot compression of tree leaf powder, alone or mixed with sawdust, for the production of panels, bricks, or any other thermoformed object using, for example, a hydraulic press or a heated extruder. The materials of the invention exhibit a significant improvement in their mechanical properties and also offer an environmentally friendly alternative to products currently on the market. The invention also relates to products obtained from these materials.

[0020] Description of the implementation methods

[0021] One object of the invention is to propose new 100% bio-based materials made from tree leaves with properties optimized for the production of panels, bricks or any other compacted object.

[0022] The present invention therefore relates to a new material comprising a mixture:

[0023] - of at least 20% and up to 100% by weight of a powder of dry dead leaves and preferably between 30% and 100% by weight of the material,

[0024] - and from 0% to 80% by weight of a sawdust powder and preferably between 0% and 70% by weight of the material,

[0025] and is characterized in that this dead leaf powder consists of leaves detached from deciduous trees, preferably having lost at least partially their green color and being dry and brittle in appearance, the size of which is between 0.1mm and 20mm for long fibers,

[0026] - and, optionally, from 0% to 20% by weight of bio-based additives, of Preference between 1% and 5% by weight of the material, which will be detailed later.

[0027]

[0028] The process for obtaining the new bio-based materials according to the invention is characterized in that what a mixture

[0029] - of at least 20% and up to 100% by weight of a powder of dried dead leaves and preferably between 30% and 100% by weight of the material,

[0030] - and from 0% to 80% by weight of a sawdust powder and preferably between 0% and 70% by weight of the material,

[0031] is subjected to hot hydraulic pressure, characterized in that the heating temperature of the mixture is greater than 80°C, advantageously greater than 100°C and less than or equal to 130°C.

[0032]

[0033] The materials obtained according to the invention are in the form of a plate, a panel, a brick or any other object that can be made by compaction.

[0034] In the context of the present invention, sawdust is defined as wood particles from trees, preferably deciduous trees. Deciduous trees are trees that produce well-developed leaves, as opposed to conifers or resinous trees whose leaves are reduced to needles. They generally lose their leaves in the fall or when the ground dries out and are called deciduous. Fallen leaves are generally collected in urban areas by municipal green space services, such as streets or public parks. The types of leaves collected come from a mixture of various deciduous trees such as ash, plane, oak, maple, linden, or horse chestnut. These leaves are then ideally washed and dried to remove impurities.

[0035] The materials obtained according to the invention have as their fields of application - the construction of furniture, shelves, wall coverings, floor coverings, ceilings - the production of solid packaging and structural supports - as well as for the manufacture of heating pellets and all similar applications which will be obvious to a person skilled in the art.

[0036]

[0037] By way of non-exhaustive examples, one can cite the production and design of chipboard panels or bricks and other elements that can be used in the manufacture of furniture, as interior objects (for cutting shelves, furniture elements such as tables, chairs, sofa frames, screens, desks or even shelves for creating scenographies), for interior design and layout, or for the manufacture of pallets or all types of structural supports due to their durability and resistance, for making decorative tiles or coasters...

[0038]

[0039] Conditionally, the materials of the invention may also incorporate bio-based additives and are derived from the categories of algae, starch, wax, vegetable gums, proteins, co-products or residues of other productions such as viscose, acids such as citric acid and / or mineral or organic colorants at a level, for example, of 0% to 20%, and preferably of 1% to 5% by mass.

[0040]

[0041] While the densities of dead leaves are, by nature, low (300 to 400 kg / m³), it was counterintuitive for a person skilled in the art to use them in a mixture to improve the strength and moisture resistance properties of a material based exclusively on sawdust, which has a much higher density. Surprisingly, the materials obtained by hot compression of powdered dead leaf mixtures according to the invention exhibit significantly increased densities (between 50% and 60% compared to compressions obtained in the absence of leaves), giving them various enhanced mechanical properties, such as strength, durability, and moisture resistance. They are in the form of solid, impact-resistant elements, more or less hard depending on the thickness obtained, thus offering possibilities for various shapes and surface textures, allowing for flexible use in different contexts. 1. Preparation of the powder from dead leaves:

[0042] The process of washing the dead leaves removes impurities that could be problematic during the subsequent stages of the process. We also remove branch residues and keep the entire leaf with its stem.

[0043] After drying, the leaves are subjected to an efficient grinding process to obtain a fine powder. This grinding can be carried out using a suitable grinder to ensure the most uniform size possible for ease of handling, generally between 0.1 mm and 20 mm for long fibers, preferably between 0.5 mm and 5 mm. 1. Preparing the mixture:

[0044] After being weighed, the powdered dead leaves, any sawdust, and optional additives are mixed using a mixer to ensure even distribution and form a homogeneous composition. The proportion of dead leaves by mass ranges from 30% to 100%. 1. Formation of the bio-based material:

[0045] The prepared mixture is deposited in a hardened steel mold and subjected to hot hydraulic pressure using a heated hydraulic press to compact the mixture.

[0046] Any type of pressure can be used as long as it is sufficient for compression; it is conventionally expressed in kilopascals or even megapascals, depending on the size of the objects and the desired characteristics. The temperature must be at least 80°C to ensure good cohesion of the material; advantageously, it will be above 100°C and up to 130°C.

[0047] The mixture in the mold must be kept under pressure for a sufficiently long period to ensure proper temperature rise and good agglomeration of the material, still under pressure, before demolding. The duration varies depending on the thickness chosen for the material.

[0048] For smaller objects such as pellets, it is also possible to use an extruder under the same temperature conditions but with much shorter residence times.

[0049] The present invention also relates to any variant or adaptation which will become clear to a person skilled in the art, if necessary by resorting to some routine trials.

[0050] Examples

[0051] It has been observed that the materials produced according to the invention have advantages and properties that may be relevant to numerous applications. Furthermore, their cutting using hand or power tools, for example a band saw or jigsaw, is clean and precise, allowing for easy and efficient cutting of sheet metal pieces with smooth edges.

Claims

Demands

1. Bio-based material comprising a mixture of: - at least 20% and up to 100% by weight of a dry dead leaf powder and preferably between 30% and 100% by weight of the material, - and 0% to 80% by weight of a sawdust powder and preferably between 0% and 70% by weight of the material, characterized in that the dead leaf powder consists of leaves detached from deciduous trees, preferably having lost at least partially their green color and being dry and brittle in appearance, the size of which is between 0.1mm and 20mm for the long fibers.

2. Bio-based material according to claim 1 comprising a mixture of: - at least 30% and up to 100% by weight of a dry dead leaf powder, - and 0% to 70% by weight of a sawdust powder.

3. Bio-based material according to claim 1 comprising 100% by weight of a powder of dried dead leaves.

4. Bio-based material according to any one of claims 1 to 3 also comprising, in addition, from 0% to 20%, and preferably from 1% to 5% by mass of bio-based additives from the categories algae, starch, wax, vegetable gums, co-products or residues of other productions such as viscose, acids, citric acid type and / or mineral or organic colorants.

5. A process for producing a bio-based material according to any one of claims 1 to 4 characterized in that a mixture: - of at least 20% and up to 100% by weight of a dry dead leaf powder and preferably between 30% and 100% by weight of the material, - and of 0% to 80% by weight of a sawdust powder and preferably between 0% and 70% by weight of the material, is subjected to hot hydraulic pressure, characterized in that the heating temperature of the mixture is greater than 80°C, advantageously greater than 100°C and less than or equal to 130°C.

6. Application in the bio-based materials industry according to claims 1 to 4 for - the construction of furniture, wall, floor, and ceiling coverings, - the production of packaging and structural supports - as well as for the manufacture of heating pellets.