WO2016135415A1 - Method for producing a reconstituted-wood type material - Google Patents

Method for producing a reconstituted-wood type material Download PDF

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Publication number
WO2016135415A1
WO2016135415A1 PCT/FR2016/050417 FR2016050417W WO2016135415A1 WO 2016135415 A1 WO2016135415 A1 WO 2016135415A1 FR 2016050417 W FR2016050417 W FR 2016050417W WO 2016135415 A1 WO2016135415 A1 WO 2016135415A1
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WO
WIPO (PCT)
Prior art keywords
wood
natural wood
wood fibers
calibrated
fibers
Prior art date
Application number
PCT/FR2016/050417
Other languages
French (fr)
Inventor
Bernard Voisin
Original Assignee
Neolife
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Publication date
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Publication of WO2016135415A1 publication Critical patent/WO2016135415A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N1/00—Pretreatment of moulding material
    • B27N1/006—Pretreatment of moulding material for increasing resistance to swelling by humidity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N1/00—Pretreatment of moulding material
    • B27N1/02—Mixing the material with binding agent
    • B27N1/029—Feeding; Proportioning; Controlling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/04—Manufacture of substantially flat articles, e.g. boards, from particles or fibres from fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N1/00—Pretreatment of moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/002—Manufacture of substantially flat articles, e.g. boards, from particles or fibres characterised by the type of binder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/08—Moulding or pressing
    • B27N3/28—Moulding or pressing characterised by using extrusion presses

Definitions

  • the present invention relates to a method of manufacturing a material, in particular an agglomerated material.
  • these coupling agents can be sensitive to the moisture present in the wood meal and therefore end up no longer fully ensure their role as a binder. This causes a heterogeneity of the material, this heterogeneity may result in deformations of the profiles obtained from this material.
  • coupling agents may pose a risk to the environment.
  • This process is based on heating and mixing a resified wood load with a binder resin. This heating and mixing takes place inside a single screw extruder.
  • Refinished wood is a wood heat treated at a temperature in the range of 240 ° C to 280 ° C to give it a hydrophobic character. Refinement improves the hygroscopic behavior of wood, ie its tendency to absorb moisture from the air, resulting in an improvement of the dimensional stability of the material obtained. In addition, it is no longer necessary to resort to the use of coupling agents.
  • a disadvantage is that the material has limited mechanical properties. Indeed, heating at temperatures between 240 ° C and 280 ° C degrades the cellulose present in the wood, so that results in a fall of the modulus of elasticity and bending stress of the final material.
  • this method provides grinding and calibration of the material after heat treatment, that is to say here after rétification.
  • the wood is very friable.
  • Post-rectification grinding and sizing destroys the wood's natural microfibrils and turns the wood into pulverulent dust. This reduces the mechanical strength of the wood, and also poses a problem of industrialization of the process since the presence of powdery dust requires the availability of special equipment, such as a suction installation.
  • Another disadvantage is a limited repeatability of the mechanical characteristics of the material obtained via this process.
  • the starting material consists of fragments of lignocellulosic material of varied and random dimensions. Depending on their size, these fragments do not react in the same way to heat treatment. As a result, the mechanical properties of a profile obtained from the final material are heterogeneous.
  • the patent document FR2930473 proposes to overcome these disadvantages, and discloses a method of manufacturing an agglomerated material having an intermediate step of preparing granules before a final step of extrusion of a profile. This intermediate step aims in particular an easier control of the manufacturing parameters.
  • this two-step sequencing makes it difficult to precisely control the weight ratio of the fiber / binder mixture. This requires recourse to compatibilizing agents.
  • the intermediate stage of preparation of granules before final extrusion involves a step of storage of these granules. During this storage, the material is exposed to moisture uptake that may aler the properties of the material, therefore those of the profile obtained at the end of the final extrusion step. Finally, the starting material is heat-treated wood in fragmented form. This raw material is often made from solid wood chips reworked by the wood industry. However, thermotrapped wood scrap from the wood industry generally has heterogeneous and limited mechanical properties.
  • the solid wood retification is difficult to control, both in terms of temperature and time of correction required.
  • the thermal heterogeneity of the treatment chamber and the impossibility of measuring the actual temperature in the various parts of the reshaped wood make it difficult to control the quality of said reshaped wood.
  • the heat treatment of the wood at high temperature leads to mechanical embrittlement of the material. It results in particular in an alteration of the flexural strength and a decrease in the modulus of elasticity. Indeed, the constituents of wood, sensitive to heat treatment at high temperature, degrade. As a result, the mechanical properties of the wood, and therefore the fiber resulting therefrom, are limited and variable.
  • the wood is generally cooled to room temperature, then the peripheral drops of this heat-treated wood are ground to provide the fragments.
  • the grinding of a wood made very brittle by the cooling and cooling at room temperature has the consequence that the natural fibers of the wood, giving it its mechanical strength, are reduced to fine dust and powder, so that Refinished wood fragments used as starting material can not be used mechanical reinforcement to the final profile.
  • these fine and powdery dusts complicate the industrialization of the process.
  • the present invention aims to overcome all or part of these disadvantages by providing a method of manufacturing a material for producing a reconstituted wood profile, dimensionally stable, and having improved mechanical properties, homogeneous and repeatable.
  • the subject of the present invention is a method of manufacturing a material, the manufacturing method comprising the steps of:
  • the process comprises, before the heat treatment step, the step of obtaining natural wood fibers, said natural wood fibers being calibrated to a predetermined size.
  • the method according to the invention offers the possibility of manufacturing a material that makes it possible to obtain dimensionally stable profiles with homogeneous and improved mechanical properties and in a repeatable manner.
  • the profiles obtained from the material produced by the process according to the invention are more resistant to tensile or compressive stresses and flexural stresses.
  • calibrated fibers having a predetermined size, also contributes to obtain a material for producing homogeneous profiles.
  • calibrated wood fibers having a predetermined size
  • This also offers the advantage of faster wood firing and better controlled, therefore more homogeneous.
  • This also makes it possible to lower the temperature and the duration of the heat treatment, compared with a retification as proposed in the state of the art.
  • This drop in heat treatment temperature preserves some constituents of natural wood, in particular fibers or cellulose, which thus provide the final section with improved mechanical characteristics.
  • the step of obtaining calibrated natural wood fibers comprises a step of grinding a natural wood in order to obtain said natural wood fibers calibrated to the predetermined size.
  • This characteristic provides control of the calibration of natural wood fibers, and also allows the selection of a natural wood species to be grinded, depending on the desired mechanical properties for the final section and to make these mechanical characteristics homogeneous and repeatable.
  • grinding and sizing are carried out on natural wood, before heat treatment, unlike the state of the art in which the grinding and sizing take place after retification, therefore after heat treatment.
  • the grinding step comprises a first grinding to obtain chips of natural wood from a solid wood, then a second grinding to obtain, from said wood chips natural, natural wood fibers calibrated to the predetermined size.
  • This grinding in two successive stages allows a precise calibration of the wood fibers, and makes it possible to use natural solid wood as starting material.
  • the use of natural solid wood as starting material has the advantage of allowing the preservation of the mechanical characteristics of solid wood in the final material.
  • the method comprises a step of controlling at least one mechanical characteristic of the profile and, if necessary, on the basis of said at least one controlled mechanical characteristic, an adjustment of at least one parameter of Manufacture among the heating temperature, the heating time, the size of calibrated natural wood fibers, the amount of binder and the natural wood species from which the calibrated natural wood fibers are obtained.
  • the method according to the invention offers the possibility of controlling and continuously correcting if necessary the quality of the profiles obtained, so as to produce profiles having improved and homogeneous mechanical characteristics, in particular if one or more characteristics of the natural wood used as raw material, for example the natural wood species used, is modified during the process.
  • the heat treatment step comprises heating these calibrated natural wood fibers to a heating temperature of between 170 ° C and 230 ° C.
  • the mechanical properties of the profiles obtained from the material thus manufactured in particular their modulus of elasticity and their resistance to bending, increase substantially, while continuing to benefit of rot-proof profiles, dimensionally stable, and devoid of coupling agents.
  • the heat treatment and mixing steps are carried out online.
  • the process according to the invention is advantageously completely carried out in situ, that is to say that all its stages from grinding to shaping and control take place on the same site, and preferably online. , one after the other in a continuous way.
  • the fact of carrying out these steps of the process in situ advantageously makes it possible to find correlations between the desired properties of the material or of the final section and of the modifications which occurred during heat treatment, with a view to developing methods for controlling the quality of the product. continuously. This is particularly advantageous when the process includes the aforementioned control step.
  • heat-treated wood fibers do not have time to cool to room temperature, which avoids embrittlement and therefore contributes to a mechanically resistant final section.
  • the temperature of the heat-treated wood fiber and binder mixture is kept below 150 ° C.
  • the temperature does not exceed 150 ° C. This avoids a degradation of mechanical properties of heat-treated wood fibers.
  • the result is a more homogenous and mechanically resistant profile.
  • the mixing step is performed by means of a rotary turbo-densifier.
  • This type of machine conventionally transforms plastic powders into granules with good flow and homogeneity characteristics.
  • the rotary turbo-densifier makes it possible to mix large quantities of wood fibers without risk of uncontrolled heating. Indeed, the temperature observed in the densification chamber, and only related to friction, does not exceed 100 °. This therefore prevents any degradation of the constituents of the heat-treated wood fiber, and therefore guarantees the completion of fine quality profiles.
  • the calibrated natural wood fibers have a predetermined size of between 2 and 6 mm.
  • the Applicant has observed that at this size of wood fibers, the natural microfibrils of the wood, which participate in the mechanical reinforcement of the final section, are preserved. They are also preserved because the grinding / sizing takes place before heat treatment of the wood.
  • Natural wood fibers also act as small thermal breakers to reduce the natural thermal expansion of the polymer, thus also providing improved dimensional stability to the profile.
  • the method comprises an initial step of selecting a natural wood species from which the calibrated natural wood fibers are obtained.
  • This characteristic has the advantage of producing profiles with predictable and homogeneous mechanical characteristics.
  • the method may comprise, after the step of mixing the heat-treated wood fibers and binder, the step: shaping the mixture of heat-treated wood fibers and binder, in particular to obtain an extrusion profile or more generally a volume 3D injection, rotational molding or 3D printing.
  • Figure 1 is a schematic view of an installation for implementing the method according to a particular embodiment of the invention.
  • Figure 1 shows an example of installation 1 for implementing the method according to the invention.
  • the method according to the invention makes it possible to manufacture a material or compound, of reconstituted wood type, that is to say of a material made of a mixture of wood and a binder, for example a thermoplastic polymer resin.
  • the method according to the invention comprises a step 1, 2 aimed primarily at obtaining natural wood fibers which are calibrated, that is to say which have a predetermined diameter.
  • the fragments, or natural wood fibers obtained to implement the method have a particle size of between [2-6] mm, which makes it possible to respect the diameter of the natural microfibrils of the wood, and thus to preserve them.
  • This step 1, 2 of obtaining calibrated natural wood fibers can advantageously comprise a step 1 of selection of a natural wood species to be used as starting material for making the profile.
  • the mechanical properties of the wood vary according to the species, this allows, knowing the wood species used, to adapt the other parameters of the manufacturing process described in more detail below, in order to obtain a profile having the desired mechanical properties .
  • the selection step preferably comprises the selection of a single species of wood or a single family of gasoline with comparable levels of hemicellulose, cellulose and lignin.
  • the wood species is selected for local availability, depending on the region where the facility is located, as well as for its affordability, in order to obtain quality profiles in large numbers and at limited costs, by limiting also the impact on the environment.
  • the natural wood used can for example come from identified forest waste or natural solid wood scrap, that is to say not having undergone treatment such as a rétification, for example branches 10 or boards 12, and known gasoline.
  • Step 1, 2 of obtaining calibrated natural wood fibers may advantageously comprise a step 2 of grinding a natural wood, in particular natural wood selected in step 1 of selection, this grinding being adapted to provide from solid natural wood or in the form of chips a few centimeters, natural wood fibers calibrated to the predetermined diameter, that is to say particle size preferably between 2 mm and 6 mm.
  • this step 2 grinding can be performed in two sub-steps: a first grinding to reduce solid wood chips, then a second grinding to calibrate the chips to obtain wood fibers calibrated to predetermined diameter .
  • the first grinding is for example carried out by means of a knife mill 20 to move from the state of massive waste, including branches or planks, chips of diameter of the order of a few centimeters.
  • the second grinding can be performed by means of a double flow mill 22 for passing chips to wood fibers calibrated to the predetermined diameter.
  • This type of mill used for the soft micronization of dry to wet materials, soft to semi-hard, is used for the pulping of cellulose, wood and annuals and grinding without heating, at high flow rates, and in margins narrow granulometry.
  • the size of the wood fibers obtained is important in the ability of the wood fibers to provide the mechanical reinforcement of the final section, and it is therefore important to avoid breaking the natural fibers of the wood.
  • the calibration by grinding takes place on natural wood, before any cooking of the wood, and respecting the diameter of the wood fibers.
  • the finest particles are removed in the process to leave only calibrated fibers.
  • the goal is to preserve the longest fibers so that they participate in the mechanical reinforcement of the final section.
  • These fibers also act as small thermal bridge breakers to reduce the natural thermal expansion of the polymer to which wood fibers will be mixed as described below. This brings increased dimensional stability to the profile obtained.
  • the method according to the invention then comprises a step 3 of heating, or roasting, calibrated wood fibers, unreflected, during a predetermined heating time and at a temperature between 170 ° C and 230 ° C, more particularly between 180 ° C and 230 ° C.
  • the temperature is between 170 ° C and 210 ° C, preferably between 180 ° C and 210 ° C.
  • the temperature of heat treatment of the fiber is for example measured by infrared thermometer in a roasting chamber.
  • this cooking step 3 is to control the gentle pyrolysis of wood (physical and chemical decomposition of organic matter under the action of heat and in the absence of oxygen), in order to remain in the zone of thermolysis of hemicelluloses and lignin crosslinking without affecting the mechanical strength of the cellulose.
  • the properties of lignins, and in particular the glass transition temperature are proportionally related to their degree of condensation, the transition phases fluctuating between 170 and 190 ° C.
  • the cellulose is slightly degraded and retains its mechanical characteristics.
  • the heat treatment step 3 can be carried out for example by means of a tunnel kiln with helical helix serving as heating transfer member.
  • This equipment has the advantage of reducing the handling of the fiber through a regular and automatic advance of the fiber during its treatment.
  • the heat treatment step 3 can be carried out by means of a horizontal oven rotating under a nitrogen atmosphere, with a maximum oxygen content of 2% in order not to reach the combustion of the wood fibers.
  • a horizontal oven rotating under a nitrogen atmosphere with a maximum oxygen content of 2% in order not to reach the combustion of the wood fibers.
  • the heat treatment stage 3 is for example carried out in a vacuum oven, which makes it possible to degrade the components of the wood which gives it its mechanical strength.
  • the heating time depends in particular on the heating temperature and the diameter of the wood fibers. The higher the temperature, or the smaller the particle size of the wood fibers, the shorter the heating time. Conversely, the higher the heating temperature is near its lower limit, or more the wood fibers have a high particle size, the longer the heating time is important. This time can vary for example between a few minutes and a few hours, depending on the technique used for roasting calibrated natural wood fibers and the volume of fibers to be treated.
  • step 3 of heat treatment the method comprises a step
  • step 3 of heat treatment and step 4 of mixing in line, that is to say to carry out mixing step 4 in the continuity of step 3 of heat treatment, directly after this, so that the temperature of heat-treated wood fibers does not fall to a storage temperature at room temperature not controllable, but stabilizes at around 50 ° C.
  • bonding the mixing step 4 to the heat treatment step 3 avoids moisture absorption of the hermetically sealed wood fibers. This, in addition to a significant energy gain, easier mixing of the load and better interaction with the resin.
  • step 2 of grinding the steps of the process, in particular step 2 of grinding, step 3 of heat treatment, step 4 of mixing, step 5 of shaping, and if necessary step 6 of control described below are performed in line, that is to say in the continuity of each other, so without intermediate storage, and without cooling, between these steps, to an ambient temperature.
  • the mixing step 4 is performed according to an advantageous embodiment by means of a machine 40 which is preferably a rotary turbo-densifier.
  • the rotary turbo-densifier comprises a drum and a worm which mixes and crushes the material against a perforated circular die. Then, knives cut the material to an average length of 3 to 5 mm. The heat during this step is derived from the friction between the pressure pieces of the rotary turbo-densifier and the matrix.
  • the temperature observed inside this machine 40 does not exceed 100 °. This avoids any degradation of the constituents of the previously heat-treated wood fiber, and consequently an alteration of the future mechanical properties of the profile.
  • the temperature of the mixture of heat-treated wood fibers and resin does not exceed a maximum temperature of 150 ° C.
  • the temperature of the mixture is, for example, stabilized at around 50 ° C., between 40 ° C. and 60 ° C.
  • the material After mixing, the material can be passed through a hot granulator to form calibrated granules to provide better rheological extrusion behavior.
  • the process then advantageously comprises a step 5 of shaping the reconstituted wood compound obtained at the end of the mixing step 4, for example to obtain a profile.
  • This step may be an extrusion step, for example by means of a conical twin-screw extruder.
  • the profile obtained at the end of the process may be a deck board, or cladding board, or slatted blade, etc.
  • the shaping step makes it possible to obtain a 3D volume, for example by injection molding, rotational molding or 3D printing.
  • the shaping step is advantageously performed in line, that is to say directly after the mixing step 4, in order to keep the heat energy released at the time of mixing step 4 and to limit any moisture recovery.
  • a resumption of moisture at this stage would require to provide a large degassing head extrusion, with a risk of bubbling that would be detrimental to the mechanical strength of extruded profiles.
  • the method also comprises a step 6 of controlling at least one mechanical characteristic of the profile, for example an analysis of the modulus of traction, flexion, water uptake and / or resistance to pressure. boiling water to assess the cohesion of the material and its conformity to the initial test pieces, in particular according to the protocol defined in the framework of the WPC certification reference system.
  • a mechanical characteristic of the profile for example an analysis of the modulus of traction, flexion, water uptake and / or resistance to pressure. boiling water to assess the cohesion of the material and its conformity to the initial test pieces, in particular according to the protocol defined in the framework of the WPC certification reference system.
  • This control is advantageously performed at regular time intervals, in order to continuously monitor the quality of the profiles manufactured.
  • This control step 6 may furthermore comprise a comparison of the values obtained with reference values.
  • control step 6 also comprises an adjustment of at least one manufacturing parameter among the heating temperature, the heating time , the diameter of calibrated natural wood fibers, the amount of binder and the species of natural wood, in order to match the values obtained during the checks with the reference values.
  • control step 6 can be performed in parallel or at the end of the shaping step, for example by means of a small extruder allowing the realization of the samples necessary for the manufacture of test pieces.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Wood Science & Technology (AREA)
  • Forests & Forestry (AREA)
  • Dry Formation Of Fiberboard And The Like (AREA)

Abstract

Said method comprises the steps; obtaining (1) natural wood fibres graded to a predetermined size, heating (3) said graded natural wood fibres to a temperature between 170 °C and 230 °C for a predetermined duration for the purpose of obtaining heat-treated wood fibres, and mixing (4) the heat-treated wood fibres with a binder. The heat treatment and mixing steps (3, 4) are carried out in-line. The method further comprises control (6) of a mechanical characteristic of the profile and, where applicable, adjustment of a production parameter selected from the heating temperature, the heating duration, the size of the graded natural wood fibres, the quantity of binder and the species of natural wood from which the graded natural wood fibres are obtained.

Description

Procédé de fabrication d'un matériau de type bois reconstitué  Method of manufacturing a reconstituted wood material
La présente invention concerne un procédé de fabrication d'un matériau, notamment un matériau aggloméré. The present invention relates to a method of manufacturing a material, in particular an agglomerated material.
II est connu de fabriquer des profilés en bois composite (WPC selon l'acronyme anglais Wood Plastic Composite), le bois composite étant classiquement formé par un mélange d'une farine de bois et d'une résine polymère thermoplastique.  It is known to manufacture composite wood profiles (WPC according to the acronym Wood Plastic Composite), the composite wood being conventionally formed by a mixture of a wood flour and a thermoplastic polymer resin.
Cependant, un inconvénient des profilés en bois composite est leur sensibilité aux variations climatiques extérieures, en raison de la très forte dilatation à la chaleur du polymère et de la reprise d'eau de la farine de bois hydrophile, pouvant provoquer des variations dimensionnelles importantes du profilé.  However, a disadvantage of composite wood profiles is their sensitivity to external climatic variations, due to the very high thermal expansion of the polymer and the water uptake of the hydrophilic wood flour, which can cause significant dimensional variations in the profile.
De plus, pour permettre le mélange de la résine polymère hydrophobe, avec la farine de bois hydrophile, il est connu de recourir à des agents de couplage destinés à enrober les particules de bois présentes dans la farine de bois.  In addition, to allow mixing of the hydrophobic polymer resin with the hydrophilic wood flour, it is known to use coupling agents for coating the wood particles present in the wood meal.
Cependant, ces agents de couplage peuvent être sensibles à l'humidité présente dans la farine de bois et finissent par conséquent par ne plus assurer complètement leur rôle de liant. Cela engendre une hétérogénéité du matériau, cette hétérogénéité pouvant se traduire par des déformations des profilés obtenus à partir de ce matériau.  However, these coupling agents can be sensitive to the moisture present in the wood meal and therefore end up no longer fully ensure their role as a binder. This causes a heterogeneity of the material, this heterogeneity may result in deformations of the profiles obtained from this material.
En outre, les agents de couplage peuvent présenter un risque pour l'environnement.  In addition, coupling agents may pose a risk to the environment.
Il est par ailleurs connu du document de brevet FR2609927 un procédé de fabrication d'un matériau aggloméré présentant une stabilité dimensionnelle améliorée par rapport aux bois composites.  It is moreover known from patent document FR2609927 a process for manufacturing an agglomerated material having improved dimensional stability compared to composite woods.
Ce procédé repose sur le chauffage et le mélange d'une charge de bois rétifié avec une résine servant de liant. Ce chauffage et ce mélange ont lieu à l'intérieur d'une unique extrudeuse à vis. Le bois rétifié est un bois ayant subi un traitement thermique à une température de l'ordre de 240°C à 280°C pour lui conférer un caractère hydrophobe. La rétification améliore le comportement hygroscopique du bois, c'est-à-dire sa tendance à absorber l'humidité de l'air, entraînant une amélioration de la stabilité dimensionnelle du matériau obtenu. De plus, il n'est plus nécessaire de recourir à l'utilisation d'agents de couplage.  This process is based on heating and mixing a resified wood load with a binder resin. This heating and mixing takes place inside a single screw extruder. Refinished wood is a wood heat treated at a temperature in the range of 240 ° C to 280 ° C to give it a hydrophobic character. Refinement improves the hygroscopic behavior of wood, ie its tendency to absorb moisture from the air, resulting in an improvement of the dimensional stability of the material obtained. In addition, it is no longer necessary to resort to the use of coupling agents.
Cependant, un inconvénient est que le matériau présente des propriétés mécaniques limitées. En effet, le chauffage à des températures comprises entre 240°C et 280°C dégrade la cellulose présente dans le bois, si bien qu'il en résulte une chute du module d'élasticité et de la contrainte en flexion du matériau final. However, a disadvantage is that the material has limited mechanical properties. Indeed, heating at temperatures between 240 ° C and 280 ° C degrades the cellulose present in the wood, so that results in a fall of the modulus of elasticity and bending stress of the final material.
De plus, ce procédé propose un broyage et un calibrage du matériau après traitement thermique, c'est-à-dire ici après rétification. Or, après rétification, le bois est très friable. Un broyage et calibrage après rétification détruit les microfibrilles naturelles du bois, et transforme ce bois en poussière pulvérulente. Cela réduit la résistance mécanique du bois, et pose aussi un problème d'industrialisation du procédé puisque la présence de poussière pulvérulente nécessite de disposer d'équipements spéciaux, comme par exemple une installation d'aspiration.  In addition, this method provides grinding and calibration of the material after heat treatment, that is to say here after rétification. However, after retification, the wood is very friable. Post-rectification grinding and sizing destroys the wood's natural microfibrils and turns the wood into pulverulent dust. This reduces the mechanical strength of the wood, and also poses a problem of industrialization of the process since the presence of powdery dust requires the availability of special equipment, such as a suction installation.
Un autre inconvénient est une répétabilité limitée des caractéristiques mécaniques du matériau obtenu via ce procédé.  Another disadvantage is a limited repeatability of the mechanical characteristics of the material obtained via this process.
Cela tient notamment à l'utilisation d'une unique extrudeuse à vis à l'intérieure de laquelle le mélange de bois rétifié et de résine est chauffé, ce qui rend difficile le contrôle de la température et de la quantité exacte de charge introduite dans le mélange.  This is due in particular to the use of a single screw extruder within which the mixture of wood and resin is heated, making it difficult to control the temperature and the exact amount of feed introduced into the machine. mixed.
De plus, le matériau de départ est constitué de fragments de matière ligno-cellulosique de dimensions variées et aléatoires. Selon leur taille, ces fragments ne réagissent pas de la même manière au traitement thermique. En conséquence, les propriétés mécaniques d'un profilé obtenu à partir du matériau final sont hétérogènes.  In addition, the starting material consists of fragments of lignocellulosic material of varied and random dimensions. Depending on their size, these fragments do not react in the same way to heat treatment. As a result, the mechanical properties of a profile obtained from the final material are heterogeneous.
Le document de brevet FR2930473 propose de pallier ces inconvénients, et divulgue un procédé de fabrication d'un matériau aggloméré ayant une étape intermédiaire de préparation de granulés avant une étape finale d'extrusion d'un profilé. Cette étape intermédiaire vise notamment un contrôle plus aisé des paramètres de fabrication.  The patent document FR2930473 proposes to overcome these disadvantages, and discloses a method of manufacturing an agglomerated material having an intermediate step of preparing granules before a final step of extrusion of a profile. This intermediate step aims in particular an easier control of the manufacturing parameters.
Cependant, bien que décomposé en deux étapes, ce procédé utilise aussi des extrudeuses à vis dans lesquelles sont chauffées et mélangées deux matières.  However, although decomposed in two stages, this process also uses screw extruders in which two materials are heated and mixed.
De plus, ce séquençage en deux étapes rend difficile le contrôle précis du rapport en poids du mélange fibres/liant. Cela impose un recours à des agents compatibilisants.  In addition, this two-step sequencing makes it difficult to precisely control the weight ratio of the fiber / binder mixture. This requires recourse to compatibilizing agents.
Aussi, l'étape intermédiaire de préparation de granulés avant extrusion finale implique une étape de stockage de ces granulés. Au cours de ce stockage, le matériau est exposé à une reprise d'humidité pouvant alétrer les propriétés du matériau, donc celles du profilé obtenu à l'issue de l'étape finale d'extrusion. Enfin, le matériau de départ est du bois thermotraité sous forme fragmentée. Cette matière première est souvent issu de chutes de bois massif rétifié de l'industrie du bois. Or, les chutes de bois thermotraité provenant de l'industrie du bois présentent généralement des propriétés mécaniques hétérogènes et limitées. Also, the intermediate stage of preparation of granules before final extrusion involves a step of storage of these granules. During this storage, the material is exposed to moisture uptake that may aler the properties of the material, therefore those of the profile obtained at the end of the final extrusion step. Finally, the starting material is heat-treated wood in fragmented form. This raw material is often made from solid wood chips reworked by the wood industry. However, thermotrapped wood scrap from the wood industry generally has heterogeneous and limited mechanical properties.
En effet, la rétification du bois massif est difficile à maîtriser, aussi bien en température qu'en temps de rétification nécessaire. L'hétérogénéité thermique de l'enceinte de traitement et l'impossibilité de mesurer la température réelle dans les différentes parties du bois rétifié, rendent difficile le contrôle qualité du dit bois rétifié.  Indeed, the solid wood retification is difficult to control, both in terms of temperature and time of correction required. The thermal heterogeneity of the treatment chamber and the impossibility of measuring the actual temperature in the various parts of the reshaped wood make it difficult to control the quality of said reshaped wood.
De plus, la rétification d'une pièce massive peut être très variable selon les essences de bois utilisées. Le choix des essences utilisées pour fournir des fibres rétifiés est donc important. Cependant, ce choix ne peut pas être maîtrisé dans le cas du recyclage des chutes de bois massif rétifié.  In addition, the repair of a massive piece can be very variable depending on the species of wood used. The choice of species used to provide staple fibers is therefore important. However, this choice can not be controlled in the case of the recycling of solid wood chips re fi tted.
Par ailleurs, le traitement thermique du bois à haute température entraîne une fragilisation mécanique du matériau. Elle se traduit notamment par une altération de la résistance à la flexion et une diminution du module d'élasticité. En effet, les constituants du bois, sensibles au traitement thermique à haute température, se dégradent. En conséquence, les propriétés mécaniques du bois, et donc de la fibre qui en est issue, sont limitées et variables.  Moreover, the heat treatment of the wood at high temperature leads to mechanical embrittlement of the material. It results in particular in an alteration of the flexural strength and a decrease in the modulus of elasticity. Indeed, the constituents of wood, sensitive to heat treatment at high temperature, degrade. As a result, the mechanical properties of the wood, and therefore the fiber resulting therefrom, are limited and variable.
De surcroît, le fait de rétifier des profils de bois massif de différentes épaisseurs peut conduire à des différences de température interne importantes et donc créer des fragments de nature hétérogène. La température à cœur d'une pièce de bois peut être nettement supérieure à la température de consigne donnée pour la rétification. Ce dépassement de la température de consigne observée est attribuée à une réaction essentiellement exothermique, qui est d'autant plus marquée que la pièce est épaisse, les gaz de pyrolyse ayant plus de difficultés pour sortir de la matrice poreuse. In fine, il existe un risque que les fragments de bois rétifié issus de ce thermotraitement présentent une hétérogénéité qui se retrouve dans le profilé final.  In addition, the fact of re-profiling solid wood profiles of different thicknesses can lead to significant differences in internal temperature and thus create fragments of heterogeneous nature. The temperature at the heart of a piece of wood can be much higher than the set temperature given for the rétification. This overshoot of the observed set temperature is attributed to an essentially exothermic reaction, which is all the more marked as the piece is thick, since the pyrolysis gases have more difficulties in getting out of the porous matrix. Ultimately, there is a risk that the pieces of wood that has been reworked from this heat treatment have a heterogeneity that is found in the final section.
Aussi, après traitement thermique, le bois est généralement refroidi jusqu'à température ambiante, puis les chutes périphériques de ce bois thermotraité sont broyées pour fournir les fragments. Comme évoqué plus haut, le broyage d'un bois rendu très cassant par la rétification puis le refroidissement à température ambiante a pour conséquence que les fibres naturelles du bois, lui procurant sa résistance mécanique, sont réduites en poussières fines et pulvérulentes, si bien que les fragments de bois rétifié utilisés comme matériau de départ ne peuvent pas servir de renfort mécanique au profilé final. En outre, ces poussières fines et pulvérulentes compliquent l'industrialisation du procédé. Also, after heat treatment, the wood is generally cooled to room temperature, then the peripheral drops of this heat-treated wood are ground to provide the fragments. As mentioned above, the grinding of a wood made very brittle by the cooling and cooling at room temperature has the consequence that the natural fibers of the wood, giving it its mechanical strength, are reduced to fine dust and powder, so that Refinished wood fragments used as starting material can not be used mechanical reinforcement to the final profile. In addition, these fine and powdery dusts complicate the industrialization of the process.
Ainsi, bien que stables dimensionnellement, les profilés obtenus à partir du procédé selon le document de brevet FR2930473 présentent des propriétés mécaniques limitées, et la répétabilité des caractéristiques mécaniques des profilés obtenus n'est pas optimale.  Thus, although dimensionally stable, the profiles obtained from the method according to the patent document FR2930473 have limited mechanical properties, and the repeatability of the mechanical characteristics of the profiles obtained is not optimal.
Aussi, la présente invention vise à pallier tout ou partie de ces inconvénients en proposant un procédé de fabrication d'un matériau permettant la réalisation d'un profilé en bois reconstitué, stable dimensionnellement, et ayant des propriétés mécaniques améliorées, homogènes et répétables.  Also, the present invention aims to overcome all or part of these disadvantages by providing a method of manufacturing a material for producing a reconstituted wood profile, dimensionally stable, and having improved mechanical properties, homogeneous and repeatable.
A cet effet, la présente invention a pour objet un procédé de fabrication d'un matériau, le procédé de fabrication comprenant les étapes :  For this purpose, the subject of the present invention is a method of manufacturing a material, the manufacturing method comprising the steps of:
chauffer des fibres de bois naturel à une température de chauffage prédéterminée et pendant une durée de chauffage prédéterminée en vue d'obtenir des fibres de bois thermotraitées, et  heating natural wood fibers to a predetermined heating temperature and for a predetermined heating time to obtain heat-treated wood fibers, and
mélanger les fibres de bois thermotraitées avec un liant, caractérisé en ce que le procédé comprend, avant l'étape de traitement thermique, l'étape : obtenir des fibres de bois naturel, lesdites fibres de bois naturel étant calibrées à une taille prédéterminée.  mixing the heat-treated wood fibers with a binder, characterized in that the process comprises, before the heat treatment step, the step of obtaining natural wood fibers, said natural wood fibers being calibrated to a predetermined size.
Ainsi, le procédé selon l'invention offre la possibilité de fabriquer un matériau permettant d'obtenir des profilés stables dimensionnellement, aux propriétés mécaniques homogènes et améliorées, et de façon répétable.  Thus, the method according to the invention offers the possibility of manufacturing a material that makes it possible to obtain dimensionally stable profiles with homogeneous and improved mechanical properties and in a repeatable manner.
En particulier, les profilés obtenus à partir du matériau fabriqué par le procédé selon l'invention sont plus résistants aux contraintes de traction ou compression et aux contraintes en flexion.  In particular, the profiles obtained from the material produced by the process according to the invention are more resistant to tensile or compressive stresses and flexural stresses.
En effet, le fait d'utiliser des fibres de bois naturel, et non du bois rétifié, comme matériau de départ permet de limiter l'hétérogénéité des propriétés mécaniques du profilé final.  Indeed, the fact of using natural wood fibers, and not wood re fi ned as starting material makes it possible to limit the heterogeneity of the mechanical properties of the final section.
En outre, le fait d'utiliser des fibres calibrées, ayant une taille prédéterminée, contribue également à obtenir un matériau permettant de réaliser des profilés homogènes.  In addition, the fact of using calibrated fibers, having a predetermined size, also contributes to obtain a material for producing homogeneous profiles.
L'utilisation de fibres de bois calibrées, ayant une taille prédéterminée, offre aussi l'avantage d'une cuisson du bois plus rapide et mieux maîtrisée, donc plus homogène. Cela permet également d'abaisser la température et la durée du traitement thermique, par rapport à une rétification comme proposé dans l'état de la technique. Cette baisse de la température de traitement thermique préserve certains constituants du bois naturel, notamment les fibres ou la cellulose, qui procurent ainsi au profilé final des caractéristiques mécaniques améliorées. The use of calibrated wood fibers, having a predetermined size, also offers the advantage of faster wood firing and better controlled, therefore more homogeneous. This also makes it possible to lower the temperature and the duration of the heat treatment, compared with a retification as proposed in the state of the art. This drop in heat treatment temperature preserves some constituents of natural wood, in particular fibers or cellulose, which thus provide the final section with improved mechanical characteristics.
Selon un mode de réalisation préféré, l'étape obtenir des fibres de bois naturel calibrées comprend une étape de broyage d'un bois naturel en vue d'obtenir lesdites fibres de bois naturel calibrées à la taille prédéterminée.  According to a preferred embodiment, the step of obtaining calibrated natural wood fibers comprises a step of grinding a natural wood in order to obtain said natural wood fibers calibrated to the predetermined size.
Cette caractéristique offre la maîtrise du calibrage des fibres de bois naturel, et permet en outre la sélection d'une essence de bois naturel à broyer, en fonction des propriétés mécaniques souhaitées pour le profilé final et afin de rendre ces caractéristiques mécaniques homogènes et répétables.  This characteristic provides control of the calibration of natural wood fibers, and also allows the selection of a natural wood species to be grinded, depending on the desired mechanical properties for the final section and to make these mechanical characteristics homogeneous and repeatable.
Par ailleurs, le broyage et le calibrage ont lieu sur du bois naturel, avant traitement thermique, à la différence de l'état de la technique dans lequel le broyage et le calibrage ont lieu après rétification, donc après traitement thermique.  In addition, grinding and sizing are carried out on natural wood, before heat treatment, unlike the state of the art in which the grinding and sizing take place after retification, therefore after heat treatment.
Cela évite de rendre le bois friable, et pulvérulent. Cela préserve les fibres naturelles du bois. Il en résulte un profilé plus résistant mécaniquement, et une industrialisation plus aisée ne nécessitant pas d'équipements spéciaux.  This avoids making the wood friable, and powdery. This preserves the natural fibers of the wood. The result is a more mechanically strong profile, and easier industrialization that does not require special equipment.
Selon un mode de réalisation préféré, l'étape de broyage comprend un premier broyage en vue d'obtenir des copeaux de bois naturel à partir d'un bois massif, puis un deuxième broyage en vue d'obtenir, à partir desdits copeaux de bois naturel, les fibres de bois naturel calibrées à la taille prédéterminée.  According to a preferred embodiment, the grinding step comprises a first grinding to obtain chips of natural wood from a solid wood, then a second grinding to obtain, from said wood chips natural, natural wood fibers calibrated to the predetermined size.
Ce broyage en deux étapes successives permet un calibrage précis des fibres de bois, et permet d'utiliser du bois massif naturel comme matériau de départ. L'utilisation de bois massif naturel comme matériau de départ a l'avantage de permettre la conservation des caractéristiques mécaniques du bois massif dans le matériau final.  This grinding in two successive stages allows a precise calibration of the wood fibers, and makes it possible to use natural solid wood as starting material. The use of natural solid wood as starting material has the advantage of allowing the preservation of the mechanical characteristics of solid wood in the final material.
Selon un mode de réalisation préféré, le procédé comprend une étape de contrôle d'au moins une caractéristique mécanique du profilé et, le cas échéant, sur la base de ladite au moins une caractéristique mécanique contrôlée, un ajustement d'au moins un paramètre de fabrication parmi la température de chauffage, la durée de chauffage, la taille des fibres de bois naturel calibrées, la quantité de liant et l'essence de bois naturel à partir de laquelle sont obtenus les fibres de bois naturel calibrées.  According to a preferred embodiment, the method comprises a step of controlling at least one mechanical characteristic of the profile and, if necessary, on the basis of said at least one controlled mechanical characteristic, an adjustment of at least one parameter of Manufacture among the heating temperature, the heating time, the size of calibrated natural wood fibers, the amount of binder and the natural wood species from which the calibrated natural wood fibers are obtained.
Ainsi, le procédé selon l'invention offre la possibilité de contrôler et corriger en continu si nécessaire la qualité des profilés obtenus, de manière à produire des profilés ayant des caractéristiques mécaniques améliorées et homogènes, en particulier si une ou plusieurs caractéristiques du bois naturel utilisé comme matière première, par exemple l'essence de bois naturel utilisée, est modifiée en cours de procédé. Selon un mode de réalisation préféré, l'étape de traitement thermique comprend le chauffage de ces fibres de bois naturel calibrées, à une température de chauffage comprise entre 170°C et 230°C. Thus, the method according to the invention offers the possibility of controlling and continuously correcting if necessary the quality of the profiles obtained, so as to produce profiles having improved and homogeneous mechanical characteristics, in particular if one or more characteristics of the natural wood used as raw material, for example the natural wood species used, is modified during the process. According to a preferred embodiment, the heat treatment step comprises heating these calibrated natural wood fibers to a heating temperature of between 170 ° C and 230 ° C.
A une température de chauffage comprise entre 170°C et 230°C, les propriétés mécaniques des profilés obtenus à partir du matériau ainsi fabriqué, en particulier leur module d'élasticité et leur résistance à la flexion, augmentent sensiblement, tout en continuant de bénéficier de profilés imputrescibles, stables dimensionnellement, et dépourvus d'agents de couplage.  At a heating temperature between 170 ° C and 230 ° C, the mechanical properties of the profiles obtained from the material thus manufactured, in particular their modulus of elasticity and their resistance to bending, increase substantially, while continuing to benefit of rot-proof profiles, dimensionally stable, and devoid of coupling agents.
Selon un mode de réalisation préféré, les étapes de traitement thermique et de mélange sont réalisées en ligne.  According to a preferred embodiment, the heat treatment and mixing steps are carried out online.
Autrement dit, ces étapes sont exécutées directement les unes à la suite des autres, de façon continue, sans interruption comme par exemple un stockage intermédiaire ou un transport du matériau d'un lieu à un autre.  In other words, these steps are executed directly one after the other, continuously, without interruption such as intermediate storage or transport of the material from one place to another.
Le procédé selon l'invention est avantageusement intégralement réalisé in situ, c'est-à-dire que toutes ses étapes depuis le broyage jusqu'à la mise en forme et le contrôle, ont lieu sur un même site, et de préférence en ligne, les unes à la suite des autres de façon continue. Le fait de réaliser ces étapes du procédé in situ permet avantageusement de trouver des corrélations entre les propriétés recherchées du matériau ou du profilé final et des modifications survenues lors du traitement thermique, en vue de mettre au point des méthodes de contrôle de la qualité du produit en continu. Cela est particulièrement avantageux quand le procédé comprend l'étape de contrôle susmentionnée.  The process according to the invention is advantageously completely carried out in situ, that is to say that all its stages from grinding to shaping and control take place on the same site, and preferably online. , one after the other in a continuous way. The fact of carrying out these steps of the process in situ advantageously makes it possible to find correlations between the desired properties of the material or of the final section and of the modifications which occurred during heat treatment, with a view to developing methods for controlling the quality of the product. continuously. This is particularly advantageous when the process includes the aforementioned control step.
Aussi, les fibres de bois thermotraitées n'ont pas le temps de refroidir jusqu'à la température ambiante, ce qui évite de les fragiliser et contribue en conséquence à un profilé final résistant mécaniquement.  Also, heat-treated wood fibers do not have time to cool to room temperature, which avoids embrittlement and therefore contributes to a mechanically resistant final section.
En outre, le risque de reprise d'humidité après thermotraitement des fibres de bois est évité. Cela permet un gain énergétique appréciable, et un malaxage de la charge plus aisée, ainsi qu'une meilleure interaction avec la résine.  In addition, the risk of moisture recovery after heat treatment of wood fibers is avoided. This allows a significant energy gain, and a mixing of the load easier, as well as a better interaction with the resin.
Selon un mode de réalisation préféré, après l'étape de traitement thermique, la température du mélange de fibres de bois thermotraitées et de liant est maintenue inférieure à 150°C.  According to a preferred embodiment, after the heat treatment step, the temperature of the heat-treated wood fiber and binder mixture is kept below 150 ° C.
Autrement dit, après traitement thermique des fibres de bois, la température n'excède pas 150°C. Cela évite une dégradation de propriétés mécaniques des fibres de bois thermotraitées. Il en résulte un profilé plus homogène et résistant mécaniquement. Selon un mode de réalisation préféré, l'étape de mélange est réalisée au moyen d'un turbo-densificateur rotatif. In other words, after heat treatment of the wood fibers, the temperature does not exceed 150 ° C. This avoids a degradation of mechanical properties of heat-treated wood fibers. The result is a more homogenous and mechanically resistant profile. According to a preferred embodiment, the mixing step is performed by means of a rotary turbo-densifier.
Ce type de machine transforme classiquement des poudres plastiques en granulés à bonnes caractéristiques d'écoulement et d'homogénéité.  This type of machine conventionally transforms plastic powders into granules with good flow and homogeneity characteristics.
Son intérêt repose aussi dans sa technicité simple, robuste et sans apport de chaleur autre que celle résultant de la friction entre les pièces de pression du turbo-densificateur rotatif et de la matrice. De plus, le turbo-densificateur rotatif permet de malaxer des quantités importantes de fibres de bois sans risque d'échauffement incontrôlé. En effet, la température observée dans la chambre de densification, et uniquement liée a la friction, ne dépasse pas les 100°. Cela prévient donc toute dégradation des constituants de la fibre de bois préalablement thermotraité, et garantit donc la réalisation in fine de profilés de qualité.  Its interest is also in its technical simplicity, robust and without any heat input other than that resulting from the friction between the pressure parts of the rotary turbo-densifier and the matrix. In addition, the rotary turbo-densifier makes it possible to mix large quantities of wood fibers without risk of uncontrolled heating. Indeed, the temperature observed in the densification chamber, and only related to friction, does not exceed 100 °. This therefore prevents any degradation of the constituents of the heat-treated wood fiber, and therefore guarantees the completion of fine quality profiles.
Selon un mode de réalisation préféré, les fibres de bois naturel calibrées ont une taille prédéterminée comprise entre 2 et 6 mm.  According to a preferred embodiment, the calibrated natural wood fibers have a predetermined size of between 2 and 6 mm.
La Demanderesse a observé qu'à cette taille de fibres de bois, les microfibrilles naturelles du bois, qui participent au renfort mécanique du profilé final, sont préservées. Elles sont aussi préservées du fait que le broyage / calibrage a lieu avant traitement thermique du bois.  The Applicant has observed that at this size of wood fibers, the natural microfibrils of the wood, which participate in the mechanical reinforcement of the final section, are preserved. They are also preserved because the grinding / sizing takes place before heat treatment of the wood.
Les fibres naturelles du bois agissent en outre comme de petits rupteurs de pont thermique afin de réduire la dilatation thermique naturelle du polymère, ce qui permet donc de procurer aussi une stabilité dimensionnelle améliorée au profilé.  Natural wood fibers also act as small thermal breakers to reduce the natural thermal expansion of the polymer, thus also providing improved dimensional stability to the profile.
Selon un mode de réalisation préféré, le procédé comprend une étape initiale de sélection d'une essence de bois naturel à partir de laquelle sont obtenues les fibres de bois naturel calibrées.  According to a preferred embodiment, the method comprises an initial step of selecting a natural wood species from which the calibrated natural wood fibers are obtained.
Cette caractéristique a l'avantage de produire des profilés aux caractéristiques mécaniques prévisibles et homogènes.  This characteristic has the advantage of producing profiles with predictable and homogeneous mechanical characteristics.
Le procédé peut comprendre, après l'étape de mélange des fibres de bois thermotraitées et de liant, l'étape : mettre en forme le mélange de fibres de bois thermotraitées et de liant, notamment pour obtenir un profilé en extrusion ou plus généralement un volume 3D en injection, rotomoulage ou impression 3D.  The method may comprise, after the step of mixing the heat-treated wood fibers and binder, the step: shaping the mixture of heat-treated wood fibers and binder, in particular to obtain an extrusion profile or more generally a volume 3D injection, rotational molding or 3D printing.
D'autres caractéristiques et avantages de la présente invention ressortiront clairement de la description détaillée ci-après d'un mode de réalisation, donné à titre d'exemple non limitatif, en référence au dessin annexé dans lequel : La figure 1 est une vue schématique d'une installation destinée à la mise en œuvre du procédé selon un mode particulier de réalisation de l'invention. La figure 1 montre un exemple d'installation 1 destinée à la mise en œuvre du procédé selon l'invention. Le procédé selon l'invention permet de fabriquer un matériau ou compound, de type bois reconstitué, c'est-à-dire en un matériau fait d'un mélange de bois et un liant, par exemple une résine polymère thermoplastique. Other features and advantages of the present invention will emerge clearly from the following detailed description of an embodiment, given by way of non-limiting example, with reference to the appended drawing in which: Figure 1 is a schematic view of an installation for implementing the method according to a particular embodiment of the invention. Figure 1 shows an example of installation 1 for implementing the method according to the invention. The method according to the invention makes it possible to manufacture a material or compound, of reconstituted wood type, that is to say of a material made of a mixture of wood and a binder, for example a thermoplastic polymer resin.
Le procédé selon l'invention comprend une étape 1, 2 visant en premier lieu à se procurer des fibres de bois naturel qui sont calibrées, c'est-à-dire qui présentent un diamètre prédéterminé.  The method according to the invention comprises a step 1, 2 aimed primarily at obtaining natural wood fibers which are calibrated, that is to say which have a predetermined diameter.
De préférence, les fragments, ou fibres de bois naturel obtenues pour mettre en œuvre le procédé ont une granulométrie comprise entre [2-6] mm, ce qui permet de respecter le diamètre des microfibrilles naturelles du bois, et d'en préserver ainsi les propriétés mécaniques avantageuses en termes de module d'élasticité et contrainte en flexion, pour que ces propriétés se retrouvent dans le profilé obtenu à l'issue du procédé.  Preferably, the fragments, or natural wood fibers obtained to implement the method have a particle size of between [2-6] mm, which makes it possible to respect the diameter of the natural microfibrils of the wood, and thus to preserve them. advantageous mechanical properties in terms of modulus of elasticity and bending stress, so that these properties are found in the profile obtained at the end of the process.
Cette étape 1, 2 d'obtention de fibres de bois naturel calibrées peut avantageusement comprendre une étape 1 de sélection d'une essence de bois naturel à utiliser comme matériau de départ pour fabriquer le profilé.  This step 1, 2 of obtaining calibrated natural wood fibers can advantageously comprise a step 1 of selection of a natural wood species to be used as starting material for making the profile.
Les propriétés mécaniques du bois variant selon les essences, cela permet, en connaissant l'essence de bois utilisée, d'adapter les autres paramètres du procédé de fabrication décrits plus détail ci-après, afin d'obtenir un profilé ayant les propriétés mécaniques souhaitées.  The mechanical properties of the wood vary according to the species, this allows, knowing the wood species used, to adapt the other parameters of the manufacturing process described in more detail below, in order to obtain a profile having the desired mechanical properties .
Afin de rendre le résultat le plus homogène et le plus prévisible possible, c'est-à-dire afin d'obtenir des profilés ayant des propriétés mécaniques homogènes et similaires, en évitant des écarts, l'étape de sélection comprend préférentiellement la sélection d'une unique essence de bois ou d'une unique famille d'essence présentant des taux d'hémicellulose, cellulose et lignine comparables.  In order to make the result as homogeneous and as predictable as possible, that is to say in order to obtain profiles having homogeneous and similar mechanical properties, avoiding gaps, the selection step preferably comprises the selection of a single species of wood or a single family of gasoline with comparable levels of hemicellulose, cellulose and lignin.
De préférence, l'essence de bois est sélectionnée pour sa disponibilité locale, selon la région où l'installation est située, ainsi que pour son coût abordable, afin d'obtenir des profilés de qualité en nombre important et à coûts limités, en limitant également l'impact sur l'environnement.  Preferably, the wood species is selected for local availability, depending on the region where the facility is located, as well as for its affordability, in order to obtain quality profiles in large numbers and at limited costs, by limiting also the impact on the environment.
Le bois naturel utilisé peut par exemple provenir de déchets forestiers identifiés ou de chutes de bois massif naturel, c'est-à-dire n'ayant pas subi de traitement comme par exemple une rétification, par exemples branches 10 ou planches 12, et d'essence connue. The natural wood used can for example come from identified forest waste or natural solid wood scrap, that is to say not having undergone treatment such as a rétification, for example branches 10 or boards 12, and known gasoline.
L'étape 1, 2 d'obtention de fibres de bois naturel calibrées peut avantageusement comprendre une étape 2 de broyage d'un bois naturel, notamment du bois naturel sélectionné à l'étape 1 de sélection, ce broyage étant adapté pour fournir à partir du bois naturel massif ou sous forme de copeaux de quelques centimètres, des fibres de bois naturel calibrées au diamètre prédéterminé, c'est-à- dire de granulométrie préférentiellement comprise entre 2 mm et 6 mm.  Step 1, 2 of obtaining calibrated natural wood fibers may advantageously comprise a step 2 of grinding a natural wood, in particular natural wood selected in step 1 of selection, this grinding being adapted to provide from solid natural wood or in the form of chips a few centimeters, natural wood fibers calibrated to the predetermined diameter, that is to say particle size preferably between 2 mm and 6 mm.
De préférence, cette étape 2 de broyage peut être réalisée en deux sous- étapes : un premier broyage permettant de réduire du bois massif en copeaux, puis un deuxième broyage permettant de calibrer les copeaux afin d'obtenir des fibres de bois calibrées au diamètre prédéterminé.  Preferably, this step 2 grinding can be performed in two sub-steps: a first grinding to reduce solid wood chips, then a second grinding to calibrate the chips to obtain wood fibers calibrated to predetermined diameter .
Le premier broyage est par exemple réalisé au moyen d'un broyeur 20 à couteau pour passer de l'état de déchets massifs, notamment branches ou planches, à des copeaux de diamètre de l'ordre de quelques centimètres.  The first grinding is for example carried out by means of a knife mill 20 to move from the state of massive waste, including branches or planks, chips of diameter of the order of a few centimeters.
Ensuite, le deuxième broyage peut être réalisé au moyen d'un broyeur 22 à double flux permettant de passer des copeaux à des fibres de bois calibrées au diamètre prédéterminé. Ce type de broyeur, utilisé pour la micronisation douce de matériaux secs à humides, mous à semi-durs, sert au défibrage de cellulose, de bois et de plantes annuelles et assure un broyage sans échauffement, à des débits élevés, et dans des marges granulométriques étroites. Comme décrit précédemment, la dimension des fibres de bois obtenues a son importance dans la capacité des fibres de bois à assurer le renfort mécanique du profilé final, et il est donc important d'éviter de casser les fibres naturelles du bois.  Then, the second grinding can be performed by means of a double flow mill 22 for passing chips to wood fibers calibrated to the predetermined diameter. This type of mill, used for the soft micronization of dry to wet materials, soft to semi-hard, is used for the pulping of cellulose, wood and annuals and grinding without heating, at high flow rates, and in margins narrow granulometry. As described above, the size of the wood fibers obtained is important in the ability of the wood fibers to provide the mechanical reinforcement of the final section, and it is therefore important to avoid breaking the natural fibers of the wood.
Ainsi, à la différence de l'état de la technique, le calibrage par broyage a lieu sur du bois naturel, avant donc toute cuisson du bois, et en respectant le diamètre des fibres de bois.  Thus, unlike the state of the art, the calibration by grinding takes place on natural wood, before any cooking of the wood, and respecting the diameter of the wood fibers.
Le fait de broyer le bois avant traitement thermique permet d'éviter de casser les microfibrilles et de réduire la production de poussière pulvérulente, cette poussière pulvérulente pouvant pénaliser la fluidité de l'extrusion ultérieure, en plus de nécessiter de disposer d'équipements spéciaux.  The fact of grinding the wood before heat treatment makes it possible to avoid breaking the microfibrils and to reduce the production of powdery dust, this powdery dust can penalize the fluidity of the subsequent extrusion, in addition to requiring the availability of special equipment.
Les plus fines particules sont éliminées dans le process pour ne laisser que les fibres calibrées. L'objectif est bien de conserver le plus de fibres longues afin qu'elles participent au renfort mécanique du profilé final.  The finest particles are removed in the process to leave only calibrated fibers. The goal is to preserve the longest fibers so that they participate in the mechanical reinforcement of the final section.
Ces fibres agissent également comme de petits rupteurs de pont thermique afin de réduire la dilatation thermique naturelle du polymère auquel les fibres de bois seront mélangés comme décrit ci-après. Cela apporte une stabilité dimensionnelle accrue au profilé obtenu. These fibers also act as small thermal bridge breakers to reduce the natural thermal expansion of the polymer to which wood fibers will be mixed as described below. This brings increased dimensional stability to the profile obtained.
On notera en plus qu'aucun broyage des fibres de bois calibrées n'aura lieu après l'étape 3 de traitement thermique décrite ci-après, à la différence de l'état de la technique.  It should be noted in addition that no grinding of the calibrated wood fibers will take place after the heat treatment step 3 described hereinafter, unlike the state of the art.
Le procédé selon l'invention comprend ensuite une étape 3 de chauffage, ou de torréfaction, des fibres de bois calibrées, non rétifiées, pendant une durée de chauffage prédéterminée et à une température comprise entre 170°C et 230°C, plus particulièrement entre 180°C et 230°C. Selon un mode de réalisation préféré, la température est comprise entre 170°C et 210°C, de préférence entre 180°C et 210°C. La température de thermotraitement de la fibre est par exemple mesurée par thermomètre infrarouge dans une chambre de torréfaction.  The method according to the invention then comprises a step 3 of heating, or roasting, calibrated wood fibers, unreflected, during a predetermined heating time and at a temperature between 170 ° C and 230 ° C, more particularly between 180 ° C and 230 ° C. According to a preferred embodiment, the temperature is between 170 ° C and 210 ° C, preferably between 180 ° C and 210 ° C. The temperature of heat treatment of the fiber is for example measured by infrared thermometer in a roasting chamber.
Le but de cette étape 3 de cuisson est de maîtriser la pyrolyse ménagée du bois (décomposition physique et chimique de matières organiques sous l'action de la chaleur et en absence d'oxygène), afin de rester dans la zone de thermolyse des hémicelluloses et de la réticulation des lignines sans affecter la résistance mécanique de la cellulose. En effet, les propriétés des lignines, et en particulier la température de transition vitreuse, sont proportionnellement liées à leur degré de condensation, les phases de transition fluctuant entre 170 et 190°C. Par contre, à 210 °C, la cellulose est peu dégradée et conserve ses caractéristiques mécaniques.  The purpose of this cooking step 3 is to control the gentle pyrolysis of wood (physical and chemical decomposition of organic matter under the action of heat and in the absence of oxygen), in order to remain in the zone of thermolysis of hemicelluloses and lignin crosslinking without affecting the mechanical strength of the cellulose. Indeed, the properties of lignins, and in particular the glass transition temperature, are proportionally related to their degree of condensation, the transition phases fluctuating between 170 and 190 ° C. On the other hand, at 210 ° C., the cellulose is slightly degraded and retains its mechanical characteristics.
L'étape 3 de traitement thermique peut être réalisée par exemple au moyen d'un four tunnel avec hélice hélicoïdale servant d'organe de transfert chauffant. Cet équipement a pour avantage de réduire la manutention de la fibre grâce a un avancement régulier et automatique de la fibre pendant son tratitement.  The heat treatment step 3 can be carried out for example by means of a tunnel kiln with helical helix serving as heating transfer member. This equipment has the advantage of reducing the handling of the fiber through a regular and automatic advance of the fiber during its treatment.
Selon une autre possibilité, l'étape 3 de traitement thermique peut être réalisée au moyen d'un four horizontal tournant sous atmosphère d'azote, avec 2% maximum d'oxygène pour ne pas atteindre la combustion des fibres de bois. Un avantage est une capacité de traitement importante pouvant s'adapter à la demande du process en ligne.  According to another possibility, the heat treatment step 3 can be carried out by means of a horizontal oven rotating under a nitrogen atmosphere, with a maximum oxygen content of 2% in order not to reach the combustion of the wood fibers. One advantage is a large processing capacity that can adapt to the demand of the online process.
Selon encore une a utre possibilité, l'éta pe 3 de traitement thermique est par exemple réalisée dans un four sous vide, ce qui permet de moins dégrader les composants du bois lui procurant sa résistance mécanique.  According to yet another possibility, the heat treatment stage 3 is for example carried out in a vacuum oven, which makes it possible to degrade the components of the wood which gives it its mechanical strength.
La durée de chauffage dépend notamment de la température de chauffage et du diamètre des fibres de bois. Plus la température est élevée, ou plus la granulométrie des fibres de bois est faible, plus la durée de chauffage est courte. A l'inverse, plus la température de chauffage est proche de sa limite inférieure, ou plus les fibres de bois ont une granulométrie élevée, plus la durée de chauffage est importante. Cette durée peut varier par exemple entre quelques minutes et quelques heures, en fonction de la technique utilisée pour la torréfaction des fibres de bois naturel calibrées et du volume de fibres à traiter. The heating time depends in particular on the heating temperature and the diameter of the wood fibers. The higher the temperature, or the smaller the particle size of the wood fibers, the shorter the heating time. Conversely, the higher the heating temperature is near its lower limit, or more the wood fibers have a high particle size, the longer the heating time is important. This time can vary for example between a few minutes and a few hours, depending on the technique used for roasting calibrated natural wood fibers and the volume of fibers to be treated.
Après l'étape 3 de traitement thermique, le procédé comprend une étape After step 3 of heat treatment, the method comprises a step
4 de mélange des fibres de bois thermotraitées avec un liant, notamment une résine polymère thermoplastique, plus d'éventuels additifs tels que des lubrifiants ou de pigments. 4 mixing heat-treated wood fibers with a binder, especially a thermoplastic polymer resin, plus any additives such as lubricants or pigments.
Il est particulièrement avantageux de réaliser l'étape 3 de traitement thermique et l'étape 4 de mélange en ligne, c'est-à-dire de réaliser l'étape 4 de mélange dans la continuité de l'étape 3 de traitement thermique, directement après celle-ci, afin que la température des fibres de bois thermotraitées ne descende pas jusqu'à une température de stockage à température ambiante non maîtrisable, mais se stabilise aux alentours de 50°C. En outre, le fait de lier l'étape 4 de mélange à l'étape 3 de traitement thermique évite une reprise d'humidité des fibres de bois hermotraitées. Cela, en plus d'un gain énergétique appréciable, un malaxage de la charge plus aisée et une meilleure interaction avec la résine.  It is particularly advantageous to carry out step 3 of heat treatment and step 4 of mixing in line, that is to say to carry out mixing step 4 in the continuity of step 3 of heat treatment, directly after this, so that the temperature of heat-treated wood fibers does not fall to a storage temperature at room temperature not controllable, but stabilizes at around 50 ° C. In addition, bonding the mixing step 4 to the heat treatment step 3 avoids moisture absorption of the hermetically sealed wood fibers. This, in addition to a significant energy gain, easier mixing of the load and better interaction with the resin.
De préférence, les étapes du procédé, notamment l'étape 2 de broyage, l'étape 3 de traitement thermique, l'étape 4 de mélange, l'étape 5 de mise en forme, et le cas échéant l'étape 6 de contrôle décrite ci-après sont réalisées en ligne, c'est-à- dire dans la continuité les unes des autres, donc sans stockage intermédiaire, et sans refroidissement, entre ces étapes, jusqu'à une température ambiante.  Preferably, the steps of the process, in particular step 2 of grinding, step 3 of heat treatment, step 4 of mixing, step 5 of shaping, and if necessary step 6 of control described below are performed in line, that is to say in the continuity of each other, so without intermediate storage, and without cooling, between these steps, to an ambient temperature.
L'étape 4 de mélange est réalisée selon un mode de réalisation avantageux au moyen d'une machine 40 qui est de préférence un turbo-densificateur rotatif. Le turbo-densificateur rotatif comprend un tambour et une vis sans fin qui mélange et écrase la matière contre une matrice circulaire perforée. Ensuite, des couteaux sectionnent la matière à une longueur moyenne de 3 à 5 mm. La chaleur lors de cette étape est issue de la friction entre les pièces de pression du turbo- densificateur rotatif et la matrice.  The mixing step 4 is performed according to an advantageous embodiment by means of a machine 40 which is preferably a rotary turbo-densifier. The rotary turbo-densifier comprises a drum and a worm which mixes and crushes the material against a perforated circular die. Then, knives cut the material to an average length of 3 to 5 mm. The heat during this step is derived from the friction between the pressure pieces of the rotary turbo-densifier and the matrix.
La température observée à l'intérieur de cette machine 40, uniquement liée à un phénomène de friction, ne dépasse pas les 100°. Cela évite toute dégradation des constituants de la fibre de bois préalablement thermotraité, et conséquemment une altération des futures propriétés mécaniques du profilé.  The temperature observed inside this machine 40, solely related to a phenomenon of friction, does not exceed 100 °. This avoids any degradation of the constituents of the previously heat-treated wood fiber, and consequently an alteration of the future mechanical properties of the profile.
Il est en effet important de maîtriser l'étape 4 de mélange de sorte que la température du mélange de fibres de bois thermotraitées et de résine ne dépasse pas une température maximale de 150°C. Comme indiqué précédemment, la température du mélange est par exemple stabilisée aux alentours de 50°C, entre 40°C et 60°C. It is indeed important to control the mixing step 4 so that the temperature of the mixture of heat-treated wood fibers and resin does not exceed a maximum temperature of 150 ° C. As indicated above, the temperature of the mixture is, for example, stabilized at around 50 ° C., between 40 ° C. and 60 ° C.
Après avoir été mélangée, la matière peut être passée à travers un granulateur à chaud permettant de former des granules calibrés de manière à offrir un meilleur comportement rhéologique en extrusion.  After mixing, the material can be passed through a hot granulator to form calibrated granules to provide better rheological extrusion behavior.
Le procédé comprend ensuite avantageusement une étape 5 de mise en forme du compound de bois reconstitué obtenu à l'issue de l'étape 4 de mélange, par exemple pour obtenir un profilé. Cette étape peut être une étape d'extrusion, par exemple au moyen d'une extrudeuse bi-vis conique. Le profilé obtenu à l'issue du procédé peut être une lame de terrasse, ou lame de bardage, ou lame de claire-voie, etc. Plus généralement, l'étape de mise en forme permet d'obtenir un volume 3D, par exemple en injection, rotomoulage ou impression 3D.  The process then advantageously comprises a step 5 of shaping the reconstituted wood compound obtained at the end of the mixing step 4, for example to obtain a profile. This step may be an extrusion step, for example by means of a conical twin-screw extruder. The profile obtained at the end of the process may be a deck board, or cladding board, or slatted blade, etc. More generally, the shaping step makes it possible to obtain a 3D volume, for example by injection molding, rotational molding or 3D printing.
L'étape de mise en forme est avantageusement réalisée en ligne, c'est-à- dire directement après l'étape 4 de mélange, afin de conserver l'énergie de chaleur dégagée au moment de l'étape 4 de mélange et de limiter toute reprise d'humidité. Une reprise d'humidité à ce stade nécessiterait de prévoir un dégazage important en tête d'extrusion, avec un risque de bullage qui serait préjudiciable à la tenue mécanique des profilés extrudés.  The shaping step is advantageously performed in line, that is to say directly after the mixing step 4, in order to keep the heat energy released at the time of mixing step 4 and to limit any moisture recovery. A resumption of moisture at this stage would require to provide a large degassing head extrusion, with a risk of bubbling that would be detrimental to the mechanical strength of extruded profiles.
Selon un mode de réalisation préféré, le procédé comprend aussi une étape 6 de contrôle d'au moins une caractéristique mécanique du profilé, par exemple une analyse du module de traction, de flexion, de reprise d'eau et/ou de résistance à l'eau bouillante permettant d'évaluer la cohésion de la matière et sa conformité aux éprouvettes initiales, notamment selon le protocole défini dans le cadre du référentiel de certification WPC.  According to a preferred embodiment, the method also comprises a step 6 of controlling at least one mechanical characteristic of the profile, for example an analysis of the modulus of traction, flexion, water uptake and / or resistance to pressure. boiling water to assess the cohesion of the material and its conformity to the initial test pieces, in particular according to the protocol defined in the framework of the WPC certification reference system.
Ce contrôle est avantageusement effectué à intervalles de temps réguliers, afin de contrôler en continu la qualité des profilés fabriqués.  This control is advantageously performed at regular time intervals, in order to continuously monitor the quality of the profiles manufactured.
Cette étape 6 de contrôle peut en outre comprendre une comparaison des valeurs obtenues avec des valeurs de référence.  This control step 6 may furthermore comprise a comparison of the values obtained with reference values.
Le cas échéant, par exemple en cas d'écart constaté entre les valeurs obtenues et les valeurs de référence, l'étape 6 de contrôle comprend aussi un ajustement d'au moins un paramètre de fabrication parmi la température de chauffage, la durée de chauffage, le diamètre des fibres de bois naturel calibrées, la quantité de liant et l'essence du bois naturel, en vue de faire concorder les valeurs obtenues lors des contrôles avec les valeurs de référence.  Where appropriate, for example in the case of deviation noted between the values obtained and the reference values, the control step 6 also comprises an adjustment of at least one manufacturing parameter among the heating temperature, the heating time , the diameter of calibrated natural wood fibers, the amount of binder and the species of natural wood, in order to match the values obtained during the checks with the reference values.
L'étape 6 de contrôle peut être réalisée en parallèle ou à l'issue de l'étape 5 de mise en forme, par exemple au moyen d'une petite extrudeuse permettant la réalisation des prélèvements nécessaire à la fabrication d'éprouvettes de contrôle. The control step 6 can be performed in parallel or at the end of the shaping step, for example by means of a small extruder allowing the realization of the samples necessary for the manufacture of test pieces.
Bien entendu, l'invention n'est nullement limitée au mode de réalisation décrit ci-dessus, ce mode de réalisation n'ayant été donné qu'à titre d'exemple. Des modifications sont possibles, notamment du point de vue de la constitution des divers éléments ou par la substitution d'équivalents techniques, sans sortir pour autant du domaine de protection de l'invention.  Of course, the invention is not limited to the embodiment described above, this embodiment having been given as an example. Modifications are possible, particularly from the point of view of the constitution of the various elements or by the substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

REVENDICATIONS
1. Procédé de fabrication d'un matériau, le procédé de fabrication comprenant les étapes : A method of manufacturing a material, the manufacturing method comprising the steps of:
- chauffer (3) des fibres de bois naturel à une température de chauffage prédéterminée et pendant une durée de chauffage prédéterminée en vue d'obtenir des fibres de bois thermotraitées, et mélanger (4) les fibres de bois thermotraitées avec un liant, dans lequel le procédé comprend, avant l'étape (3) de traitement thermique, l'étape (1) : obtenir des fibres de bois naturel, lesdites fibres de bois naturel étant calibrées à une taille prédéterminée,  heating (3) natural wood fibers to a predetermined heating temperature and for a predetermined heating time to obtain heat-treated wood fibers, and mixing (4) the heat-treated wood fibers with a binder, wherein the method comprises, before step (3) of heat treatment, step (1): obtaining natural wood fibers, said natural wood fibers being calibrated to a predetermined size,
l'étape (3) de traitement thermique comprenant le chauffage de ces fibres de bois naturel calibrées, à une température de chauffage comprise entre 170°C et 230°C,  the heat treatment step (3) comprising heating said calibrated natural wood fibers to a heating temperature of between 170 ° C and 230 ° C,
les étapes (3, 4) de traitement thermique et de mélange étant réalisées en ligne, et  the steps (3, 4) of heat treatment and mixing being carried out online, and
le procédé comprenant une étape (6) de contrôle d'au moins une caractéristique mécanique du profilé et, le cas échéant, sur la base de ladite au moins une caractéristique mécanique contrôlée, un ajustement d'au moins un paramètre de fabrication parmi la température de chauffage, la durée de chauffage, la taille des fibres de bois naturel calibrées, la quantité de liant et l'essence de bois naturel à partir de laquelle sont obtenus les fibres de bois naturel calibrées.  the method comprising a step (6) of controlling at least one mechanical characteristic of the profile and, if appropriate, on the basis of said at least one controlled mechanical characteristic, an adjustment of at least one manufacturing parameter among the temperature heating time, the heating time, the size of calibrated natural wood fibers, the amount of binder and the natural wood species from which the calibrated natural wood fibers are obtained.
2. Procédé selon la revendication 1, dans lequel l'étape (1) obtenir des fibres de bois naturel calibrées comprend une étape (2) de broyage d'un bois naturel en vue d'obtenir lesdites fibres de bois naturel calibrées à la taille prédéterminée. The method according to claim 1, wherein the step (1) of obtaining calibrated natural wood fibers comprises a step (2) of grinding a natural wood to obtain said natural wood fibers calibrated at the waist. predetermined.
3. Procédé selon la revendication 2, dans lequel l'étape (2) de broyage comprend un premier broyage en vue d'obtenir des copeaux de bois naturel à partir d'un bois massif, puis un deuxième broyage en vue d'obtenir, à partir desdits copeaux de bois naturel, les fibres de bois naturel calibrées à la taille prédéterminée. 3. Method according to claim 2, wherein the grinding step (2) comprises a first grinding to obtain natural wood chips from a solid wood, then a second grinding to obtain, from said natural wood chips, the natural wood fibers calibrated to the predetermined size.
4. Procédé selon l'une des revendications 1 à 3, dans lequel, après l'étape (3) de traitement thermique, la température du mélange de fibres de bois thermotraitées et de liant est maintenue inférieure à 150°C. 4. Method according to one of claims 1 to 3, wherein, after the step (3) of heat treatment, the temperature of the mixture of heat-treated wood fiber and binder is kept below 150 ° C.
5. Procédé selon l'une des revendications 1 à 4, dans lequel l'étape (4) de mélange est réalisée au moyen d'un turbo-densificateur rotatif. 5. Method according to one of claims 1 to 4, wherein the step (4) of mixing is performed by means of a rotary turbo-densifier.
6. Procédé selon l'une des revendications 1 à 5, dans lequel les fibres de bois naturel calibrées ont une taille prédéterminée comprise entre 2 et 6 mm. 6. Method according to one of claims 1 to 5, wherein the calibrated natural wood fibers have a predetermined size of between 2 and 6 mm.
7. Procédé selon l'une des revendications 1 à 6, dans lequel le procédé comprend une étape initiale de sélection d'une essence de bois naturel à partir de laquelle sont obtenues les fibres de bois naturel calibrées. 7. Method according to one of claims 1 to 6, wherein the method comprises an initial step of selecting a natural wood species from which are obtained calibrated natural wood fibers.
PCT/FR2016/050417 2015-02-23 2016-02-23 Method for producing a reconstituted-wood type material WO2016135415A1 (en)

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EP2233261A1 (en) * 2009-03-23 2010-09-29 China Foma (Group) Co., Ltd. A method for pressing mats with a continuous press and an apparatus for performing the method
WO2012168563A2 (en) * 2011-06-09 2012-12-13 Ekolite Oy Process for a natural fiber composite material manufacturing, products obtained and methods of application thereof
FR2989016A1 (en) * 2012-04-06 2013-10-11 Dumoulin Bois Method for printing relief pattern on face of wood plate or wooden derivate panel to manufacture e.g. terrace floor, involves compressing die on solid wood or wood derivative panel at cold by using press, and printing pattern on panel face

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3091306A1 (en) 2018-12-26 2020-07-03 Vinci Construction France Facade cladding element for energy renovation

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FR3032903A1 (en) 2016-08-26

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