Method for producing an optimised insulating panel, insulating panel and insulating structure comprising such a panel

Abstract

The invention relates to a method for producing an insulating panel based on cereal straw, characterised in that it comprises the steps of: a) mechanically shredding and screening the straw to obtain a defibred straw of which the strands have an average length of between 3 mm and 11 mm and of which the average diameter is between 0.5 mm and 2.5 mm; b) using a mixer and mixing the defibred straw with a binding material with a proportion by weight of between 3% and 25% and preferably between 4% and 10%; c) injecting compressed air into the mixture to homogenise the mixture; d) heating and calibrating the length and width of the insulating panel; e) calibrating the thickness of the material making up the insulating panel; f) heating the insulating panel to a temperature of at least 90°C and preferably between 110°C and 150°C, throughout the thickness of the insulating panel and for a period of at least 3 minutes; g) cooling the insulating panel to ambient temperature; and h) packaging the insulating panel.

Description

[0001] METHOD FOR MANUFACTURING AN OPTIMISED INSULATING PANEL, INSULATING PANEL AND INSULATING STRUCTURE COMPRISING SUCH A PANEL

[0002] Technical field

[0003] The present invention relates to the general technical field of insulating materials used in construction. These insulating materials are generally intended to cover a wall or roof to provide thermal and sound insulation. These insulating materials, for example in the form of rigid or semi-rigid insulating panels, can also be integrated into prefabricated modular structures made of wood or concrete.

[0004] These insulating materials must also comply with national and / or European standards and have a fire classification.

[0005] In France and other countries, public and private tender specifications increasingly require the use of bio-sourced insulation materials with the smallest possible ecological footprint. These insulating materials are, for example, made from renewable and recyclable raw materials, such as wood fibers, cellulose wadding, textile fibers, expanded cork, hemp, sheep's wool, or other bio-sourced materials.

[0006] “Bio-sourced materials” are materials derived from renewable organic matter (biomass) of plant or animal origin.

[0007] The invention relates more particularly to the manufacture of such insulating materials in the form of insulating panels.

[0008] Prior art

[0009] For example, we know the use of cereal straw to insulate a wall or to make such a wall with bales of straw. These must then be combined with elements such as facing to obtain the regulatory fire resistance, watertightness and airtightness performances. These sub-assemblies generally have wall thicknesses greater than those obtained with non-biosourced insulating materials in order to compensate for their very average or poor thermal conductivity value (lambda -).

[0010] It should also be noted that most known bio-based insulating materials are not suitable or permitted, given their limited fire retardant performance, for buildings with more than three floors.

[0011] The current use of straw as an insulating material has many disadvantages. These disadvantages include the limitation to buildings with a maximum of three floors, the bulkiness of straw bales, the significant generation of dust and debris, the increase in the weight of the structure given the thickness of the insulating material, the need to add non-biosourced materials such as gypsum board or rock wool, and it is not available as a mass-produced, industrially manufactured product.

[0012] Document WO 2018 / 018079 A1 discloses a method for manufacturing a panel based on rice straw mixed with a binder material such as phenolic resin. The method consists of obtaining a moisture content of the rice straw below 12%, then forming the panel by heating the mixture to a high temperature, above 150°C and up to 250°C and compressing the mixture by applying high pressure. Such operating parameters are very complicated to implement and negatively affect the energy costs and profitability of the said manufacturing process. The described method requires the use of a stationary press to obtain the desired high pressure and high temperatures. This makes continuous production impossible.

[0013] Presentation of the invention

[0014] The object of the invention therefore aims to overcome the drawbacks of the prior art by proposing a new process for manufacturing insulating panels from an ecological, renewable, recyclable raw material available in almost all rural areas.

[0015] Another object of the invention is to propose a method for manufacturing insulating panels, which is easy to implement and economical.

[0016] Another object of the invention is to provide insulating panels having excellent fire retardant, thermal insulation and sound insulation performance.

[0017] Another object of the invention is to provide insulating panels having sufficient properties and performance to allow their use in buildings with more than three floors.

[0018] Another object of the invention is to provide prefabricated insulating modular elements, having excellent fire retardant and thermal and sound insulation performance.

[0019] The objects assigned to the invention are achieved using a method for the continuous manufacture of an insulating panel based on cereal straw, characterized in that it comprises the steps: a) mechanically grinding the straw to obtain a defibrated straw whose strands have an average length of between 3 mm and 22 mm and preferably between 3 mm and 11 mm and whose average diameter is between 0.5 mm and 4.0 mm and preferably between 0.5 mm and 2.5 mm, b) using a mixer and mixing the defibrated straw with a binder material introduced into the mixer with a mass proportion of between 3% and 25% and preferably between 3% and 10% and more preferably between 3% and 9% relative to the total mass of the mixture, c) injecting compressed air into the mixture to homogenize said mixture, d) depositing the mixture on a conveyor,e) calibrating the thickness of the mixture to form a continuous strip of mixture of determined thickness, f) heating the strip of mixture to bring it to and / or maintain it at a temperature of at least 90°C and preferably between 110°C and 150°C and more preferably between 110°C and 145°C, throughout the thickness of said strip of mixture over a heating time d, c , g) cooling the insulating strip thus obtained to room temperature or close to room temperature and calibrating the width and length of said insulating strip to form the insulating panel, and h) packaging the insulating panel.

[0020] According to an exemplary implementation, the method consists in step a) of using at least one grinder to shred and grind the straw into bales, said at least one grinder comprising adjustable shredding / grinding tools to define the shape and dimensional properties of the strands of defibrated straw obtained, said tools comprising knives and hammers in series.

[0021] According to an exemplary implementation, the method consists, in steps b), c) and d), of using at least one mixer (3) of the rotating cylinder type, associated downstream with a drop cage.

[0022] According to an exemplary implementation, the method consists of filtering the defibrated straw obtained under a) to remove dust and other impurities in a proportion by mass of at least 2% and preferably at least 5% to 10% of the defibrated straw.

[0023] According to an example of implementation, the method consists in step e) of exerting linear pressure on the insulating panel in formation, by means of a compression roller. As another example, it is also possible to use pressure strips, a mold or a stainless steel mesh, to carry out the thickness calibration.

[0024] According to an exemplary implementation, the binder material comprises a hot-melt two-component binder chosen from two-components comprising polylactic biopolymer fibers of the PLA / Co-PLA, PLA / PBS type obtained from cereals.

[0025] According to another example of implementation, the binding material comprises a two-component hot-melt binder comprising Polyester / Polyethylene, Polyester / PBT fibers.

[0026] According to an exemplary implementation, the method consists of mixing the binder material, or the mixture of defibrated straw and the binder material, with one or more adjuvants comprising a fungicidal product with a proportion by mass relative to the total mass of the mixed products, of between 0.03% and 11% and preferably of between 0.5% and 4%.

[0027] According to another example of implementation, after step f) and preferably after formatting the mixture in length and width, the method consists of spraying on each face of said mixture, one or more adjuvants comprising a fungicidal product with a proportion by mass relative to the total mass of the mixed products, of between 0.03% and 11% and preferably of between 0.5% and 4%.

[0028] For example, the adjuvants include a fire retardant product with a mass proportion relative to the total mass of the mixed products, between 24% and 72%. The fire retardant product is chosen, for example, from products in a family of geo-sourced products.

[0029] For example, the fire retardant product is in viscous or liquid form and comprises a geopolymer of the metakaolin type.

[0030] Advantageously, the method comprises an operation of disentangling and aerating the binding material prior to step b).

[0031] According to an exemplary implementation, step f) is implemented using on the one hand a high-frequency or microwave heating system to heat the mixing strip in depth and on the other hand an additional heating system to heat the mixing strip at its free peripheral edges, said additional heating system comprising an infrared heating system.

[0032] According to another exemplary embodiment, the additional heating system may comprise infrared and / or pulsed air heating means.

[0033] Advantageously, the method consists of controlling the forward speed of the conveyor so that the mixing belt crosses an active heating zone for a duration corresponding to the minimum heating duration d c, of at least 3 minutes. This minimum heating time dc depends on a set of parameters including the humidity of the mixture, the density of the mixture, the thickness of the mixing strip, the type of binder material used, the thermal energy used and / or the duration of exposure to the heat treatment.

[0034] According to an exemplary implementation, the method consists of using at least one sensor and / or probe to measure the temperature at the edge of the mixing strip and using at least one sensor and / or probe to measure the core temperature of said mixing strip and continuously controlling the heating systems according to values ​​measured by said sensors and / or probes.

[0035] According to an exemplary implementation, the method consists of using at least one sensor and / or probe to measure the humidity level of the mixture during step d) or e) and controlling the heating systems according to values ​​measured by said sensor and / or probe.

[0036] According to an exemplary implementation, the method comprises a step of applying to at least one face of the insulating panel, a fire-retardant or flame-retardant coating, which has a thickness of at least 0.5 mm.

[0037] The objects assigned to the invention are also achieved using an insulating panel or insulating assembly, rigid or semi-rigid, comprising at least one panel obtained by the manufacturing method as presented above, said panel having a density of between 50 kg / m 3 and 150 kg / m 3 and preferably between 60 kg / m 3 and 100 kg / m 3 .

[0038] The objects assigned to the invention are also achieved using a rigid or semi-rigid insulating panel comprising a first panel obtained by the manufacturing process as presented above, and on which is glued an additional fire-retardant panel, the additional panel also being obtained by the same manufacturing process, with a fire-retardant product having a proportion by mass relative to the total mass of the mixed products greater than 49%.

[0039] The objects assigned to the invention are also achieved using a prefabricated modular structure made of wood or mixed concrete-wood to create a wall or to cover a wall of a building, on the exterior or interior side, characterized in that it comprises at least one insulating panel manufactured according to the method as presented above.

[0040] The manufacturing process according to the invention provides the remarkable advantage that the insulating panels obtained have a very high homogeneity throughout their entire thickness. The process according to the invention makes it possible to heat the core of the insulating panels sufficiently to obtain complete and homogeneous polymerization throughout the entire thickness of said insulating panels. This makes it possible to improve their performance in terms of thermal and sound insulation of said panel as well as the strength of said panels over time.

[0041] Another advantage of the process according to the invention lies in the production of insulating panels whose fire reaction classification allows them to be adapted to meet the various standards and legislation in force. The insulating panels obtained using the process according to the invention also have remarkable performances. Indeed, these panels have a thermal conductivity coefficient lambda-X of 0.038, which is remarkable, knowing that the thermal conduction coefficient is between 0.052 and 0.080 for straw, between 0.037 and 0.044 for expanded cork and between 0.037 and 0.042 for cellulose wadding.

[0042] The process according to the invention makes it possible to obtain insulating panels whose handling and storage are greatly facilitated. The insulating panels are in fact of reduced weight and size compared in particular to bales of straw.

[0043] Another advantage of the method according to the invention lies in its implementation at low temperatures and pressures compared to those used in the prior art. It is therefore unnecessary to use a stationary press. This results in a simpler and more economical implementation of the manufacturing process. In addition, continuous production can be implemented simply.

[0044] The process according to the invention makes it possible, in a remarkable and unexpected way, to distribute the thermal energy supplied to the mixture in a homogeneous manner, at the core and at the periphery within the framework of a continuous friction process.

[0045] Brief description of the figures

[0046] Other characteristics and advantages of the present invention will appear more clearly on reading the description which follows, given with reference to the appended drawing, given by way of non-limiting example, in which:

[0047] - figure 1 is a schematic view of a flowchart of an example of implementation of the manufacturing method according to the invention,

[0048] - figure 2 is a schematic view of a flowchart of another example of implementation of the manufacturing method according to the invention,

[0049] - Figure 3 is a schematic view of a flowchart of a variant of the implementation example illustrated in Figure 2,

[0050] - figure 4 a schematic view of a flowchart of an additional example of implementation of the manufacturing method according to the invention, and - figure 5 a schematic view of a flowchart of another additional example of implementation of the manufacturing method according to the invention.

[0051] Detailed description of the invention

[0052] Structurally and functionally identical elements present in several distinct figures are assigned the same numerical or alphanumeric reference.

[0053] Figure 1 is an illustration of an example of an installation for implementing the process of manufacturing insulating panels from cereal straw, such as wheat, barley, oats, rapeseed, miscanthus, rice straw or various mixtures thereof.

[0054] The installation includes a grinding unit 1 for transforming raw straw into defibrated straw by shredding and grinding.

[0055] The crushing and defibering unit 1 advantageously comprises tools for cutting and splitting the straw strands. For example, the crushing and defibering unit 1 comprises two crushers connected in series. The first crusher comprises, for example, tools for cutting the straw strands, such as knives. The second crusher comprises, for example, tools for splitting the straw strands, such as hammers.

[0056] Defibrated straw means straw comprising cut and split strands with an average length of between 3 mm and 22 mm and an average diameter of between 0.5 mm and 4.0 mm. Preferably, defibrated straw strands have an average length of between 3 mm and 11 mm and an average diameter of between 0.5 mm and 2.5 mm.

[0057] The average diameter must be understood as being the largest dimension of the straw blade, taken in a plane orthogonal to the longitudinal direction of said blade.

[0058] For example, a defibrated straw comprises from 29% to 33% of strands having an average length of 9.633 mm with an average diameter greater than 2 mm, from 32% to 37% of strands having an average length of 6.951 mm with an average diameter greater than 1 mm and from 16% to 20% of strands having an average length of 3.960 mm with an average diameter greater than 0.5 mm.

[0059] The remainder of this sample is considered to be dust, which is preferably removed by filtration using a filtration / dosing unit 2

[0060] Figure 1 illustrates, using a flowchart, an example of the implementation of a process for manufacturing an insulating material from cereal straw, such as wheat, barley, oats, rapeseed, miscanthus, rice straw or various mixtures thereof.

[0061] The installation includes a crushing and defibering unit 1 for transforming raw straw into defibered straw by shredding and crushing.

[0062] By defibrated straw, it is preferable to understand a straw comprising non-homogeneous strands, of average length between 3 mm and 11 mm and whose average diameter is between 0.5 mm and 2.5 mm.

[0063] The average diameter must be understood as being the largest dimension of the straw blade, taken in a plane orthogonal to the longitudinal direction of said blade.

[0064] For example, a defibrated straw comprises from 29% to 33% of strands having an average length of 9.633 mm with an average diameter greater than 2 mm, from 32% to 37% of strands having an average length of 6.951 mm with an average diameter greater than 1 mm and from 16% to 20% of strands having an average length of 3.960 mm with an average diameter greater than 0.5 mm.

[0065] The remainder of this sample sample is considered dust, which is preferably removed by filtration using a filtration / dosing unit 2.

[0066] The manufacturing process is, for example, implemented using an installation illustrated schematically with the flowchart in Figure 1.

[0067] The installation comprises a crushing / shredding unit 1 fed with straw, for example, packaged in bales. The crushing / shredding unit 1 comprises, for example, two crushers in series, which may include crushing tools with specific shapes or settings.

[0068] The crushers advantageously include adjustable shredding and grinding tools to define the shape and size parameters of the strands of the defibrated straw.

[0069] According to another embodiment of the installation, the crushing / shredding unit 1 comprises knives for cutting the straw strands and hammers for splitting said strands. In the context of the implementation of the shredding and grinding of the straw, one or more passes may be provided in the crushing / shredding unit 1. The number of passes depends on the morphology (shape, length and diameter) sought for the defibrated straw strands. A defibrated straw is thus obtained, at the outlet of the crushing / shredding unit 1, composed of dimensionally and shape-optimized strands, to promote their mixing with a binder material on the one hand and to improve the thermal insulation, sound insulation and mechanical properties of the solid insulating material obtained on the other hand.

[0070] According to an exemplary embodiment, the installation also comprises a filtering and dosing unit 2 which directly feeds a mixer 3.

[0071] The filtering operation is carried out, for example, by using a vibrating screen and / or a cyclonic separator. The latter can advantageously be used to transfer the defibrated straw to the mixer 3. Filtering makes it possible to separate the defibrated straw from dust and other impurities by gravity or by cyclonic filtering.

[0072] The mixer 3 comprises, for example, at least one mixer of the rotating cylinder type, associated downstream with a drop cage. Advantageously, it is possible to use several drop cages and / or one or more buffer tanks containing the mixture in order to ensure continuity in the supply of the conveyor.

[0073] The installation also comprises a first dosing and spraying unit 4a for supplying the mixer 3 with adjuvants. These adjuvants comprise at least one fungicidal adjuvant F. These adjuvants may also comprise a fire-retardant adjuvant R.

[0074] The installation also includes a second dosing and spraying unit 4b to supply the mixer 3 with the binder material.

[0075] The installation advantageously comprises a disentangling and aeration unit 5 for decompacting the binder material before it is dosed and sprayed into the mixer 3. The disentangling and aeration unit 5 comprises, for example, a carding system so as to separate the constituent fibers of the binder material. The installation also comprises a compressor 6 for injecting compressed air into the mixer 3, thus promoting the homogenization and aeration of the mixture.

[0076] The installation also comprises a formatting and calibrating unit 7 for at least the thickness of the mixture at the outlet of the mixer 3. This formatting and calibrating unit 7 makes it possible, for example by molding, to produce a strip of mixture of determined shape and thickness.

[0077] The installation also includes a heating unit 8 for heating the mixing strip throughout its thickness and thus obtaining the crosslinking of the binding material and consequently the stiffening of the mixing strip or the preformed insulating panel.

[0078] The installation also comprises a cooling unit 9 for the mixing belt or the insulating panel, at the outlet of the heating unit 8. The cooling unit 9 may consist, for example, of an ambient air conveyor, bringing the insulating panel to a packaging unit 10. The cooling unit 9 may also comprise an intermediate storage area, for the time necessary for cooling the insulating panel.

[0079] Figure 2 is a schematic view of a flowchart of another example of implementation of the method for manufacturing the insulating panel. The installation for this purpose comprises a bonding unit 11, which allows, downstream of the cooling unit 9, to bond an additional rigid fire-retardant panel to the rigid or semi-rigid insulating panel. This additional panel is for example made with known materials, for example based on plaster or others.

[0080] According to another example of implementation of the method, the additional panel is also obtained by the manufacturing method according to the invention. The fire-retardant product then advantageously has a proportion by mass relative to the total mass of the mixed products greater than 49%. This additional panel then has a greater density and a smaller thickness than the first rigid or semi-rigid insulating panel. This results in an assembly having excellent thermal and sound insulation properties as well as good fire-retardant performance.

[0081] Figure 3 is a schematic view of a flowchart of another example of implementation of the method for manufacturing the insulating panel. The installation comprises for this purpose an application unit 12, which allows, downstream of the cooling unit 9, to coat the rigid or semi-rigid insulating panel with a fire-retardant or flame-retardant coating. This coating is for example produced with a known fire-retardant product.

[0082] The insulating panel is then placed in a drying unit 13 before being conveyed to the packaging unit 10.

[0083] Figure 4 is a flowchart illustrating an additional example of implementation of the manufacturing method according to the invention. The installation for implementing the method comprises a complementary mixing and heating unit 7a at the outlet of the mixer 3. By way of example, the complementary mixing and heating unit 7a advantageously comprises a drop cage into which preheated air is injected.

[0084] According to an example of implementation, it is possible to use infrared lamps and / or air heated by electrical resistors to heat the mixture in the drop cage.

[0085] Downstream of the drop cage, the installation comprises a conveyor and a calibration and heating unit 8a, for example in the form of a heating mold, into which the mixture from said drop cage is transferred by gravity or by conveying.

[0086] The heating operation thus continues during and / or after the thickness calibration of the mixing strip before the cooling operation. The heating of the mixture continues to allow temperature maintenance for a minimum heating time and to obtain optimal crosslinking of the binder material in the mixture.

[0087] Step f), according to another embodiment, the calibration and heating unit 8a comprises a system producing heated air, which is injected under pressure into the preformed insulating panel at least in thickness.

[0088] Heating the mixture allows the binding material to crosslink, which then forms a rigid three-dimensional network in which the strands of defibrated straw and the fibers of the binding material are bound together.

[0089] Due to the cut and split configuration of the defibrated straw strands, the latter are also mechanically fixed in said rigid network of cross-linked binding material.

[0090] Figure 5 is a schematic view of a flowchart of another example of implementation of the manufacturing method according to the invention. In this example of implementation, the installation comprises in series a first mixer 3a and a second mixer 3b.

[0091] The defibrated straw, at the outlet of the filtration and dosing unit 2, is conveyed into the first mixer 3a, as is the binding material at the outlet of the second dosing and spraying unit 4b.

[0092] Depending on the specific characteristics required for the insulating panel, a mixture A prepared in the first mixer 3a, with the addition, if necessary, of a fungicidal adjuvant F, is conveyed to the formatting and calibration unit 7 (arrow A).

[0093] Depending on other specific characteristics sought for the insulating panel, the mixture A prepared in the first mixer 3a, with the addition where appropriate of a fungicidal adjuvant F, is conveyed to the second mixer 3b.

[0094] An additional spray dosing unit 4c can then inject a fire-retardant additive R into the second mixer 3b. This produces a mixture B which will be sent to the formatting and calibration unit 7. Mixture B will then lead to the production of an insulating panel with more or less marked “fire-retardant” properties, depending on the nature and mass proportion of the fire-retardant additive R used.

[0095] The insulating material in the form of a panel is therefore manufactured according to an example of implementation of the manufacturing process detailed below.

[0096] The process for manufacturing the insulating material based on cereal straw comprises a step a) consisting of grinding, shredding or mechanically cutting the straw to obtain a defibrated straw whose strands preferably have an average length of between 3 mm and 11 mm and whose average diameter is between 0.5 mm and 2.5 mm.

[0097] Advantageously, the method consists of filtering the defibrated straw obtained under a) to remove dust and other impurities in a proportion by mass of at least 2% and preferably 5% to 10% of the defibrated straw. The separation of undesirable residues and dust or other materials affecting the performance of the insulating material can therefore be carried out by gravity using a sieve, for example a vibrating sieve, or using cyclonic filtering. This filtration and separation advantageously makes it possible to reduce the risk of explosion, linked to the concentration of dust in the air on the manufacturing sites.

[0098] According to step b), the mixer 3 is used to mix the defibrated straw with a binder material, introduced into the mixer 3 for example by spraying, with a mass proportion of between 3% and 25% and preferably between 3% and 10% and more preferably between 3% and 9% relative to the total mass of the mixture.

[0099] According to an advantageous implementation example, the method comprises an operation of disentangling and aerating a two-component binder material prior to step b). This preparation of the binder material comprises, for example, a carding operation. This disentangling and aeration phase can, for example, be carried out separately or directly in the mixer 3 before the introduction of the binder material.

[0100] The defibrated straw is then introduced in turn into the mixer 3 or into the first mixer 3a, after the binding material.

[0101] According to step c), compressed air is injected into the mixture and more precisely into the mixer 3, into the first mixer 3a and where appropriate into the second mixer 3b, to homogenize said mixture.

[0102] Then, according to step d), the mixture is deposited, by gravity, onto a conveyor belt or other type.

[0103] According to the following step e), the mixture is calibrated in thickness to form a continuous strip of determined thickness. For example, linear pressure is exerted on the strip of mixture by means of a compression roller, to carry out the thickness calibration.

[0104] Then, according to a step f), the mixing strip is heated to bring it to or maintain it at a temperature of at least 90°C and preferably between 110°C and 150°C and more preferably between 110°C and 145°C, throughout the thickness of the mixing strip, over a heating time d cof at least 3 minutes. Then, according to a step g), the insulating strip thus obtained is cooled to room temperature or to a temperature close to room temperature. During this step g), the width and length of the insulating panel obtained by peripheral cutting of the rigid or semi-rigid insulating strip is also calibrated. This operation is carried out in a manner known per se, for example using saws.

[0105] Finally, we proceed, according to step h), to the packaging of the insulating panel.

[0106] According to a preferred example, step f) is implemented using on the one hand a high-frequency or microwave heating system to heat the mixing strip in depth and on the other hand an additional heating system to heat the mixing strip at its free peripheral edges. By way of example, the heat treatment of the mixture is obtained at least in part by means of a high-frequency heating system. The frequency used is for example 13.56 MHz. According to another exemplary implementation, the heat treatment of the mixture is obtained at least in part by means of a microwave heating system. The frequency used is then for example 915 MHz or 2450 MHz.

[0107] The additional heating system advantageously comprises an infrared radiation heating system. Several infrared radiation heating systems may be used so as to irradiate all of the peripheral faces, in particular the free peripheral edges of the mixing strip.

[0108] Advantageously, the manufacturing method consists of controlling the forward speed of the conveyor so that the conveyed mixing belt crosses an active heating zone for a duration corresponding to the minimum heating duration of c .

[0109] Advantageously, the manufacturing method consists of using at least one sensor to measure the temperature at the edge of the mixing strip and using at least one sensor to measure the core temperature of said mixing strip. The heating system and the additional heating system are then continuously controlled according to values ​​measured by said sensors. Maintaining a minimum temperature at the edge of the mixing strip ensures uniform crosslinking of the binder material, even at the edge of said mixing strip.

[0110] Advantageously, the manufacturing method consists of using at least one sensor to measure the moisture content of the mixture during step d) or e) and controlling the heating systems according to values ​​measured by said sensor. The moisture content of the mixture is advantageously between 5% and 40% and preferably between 12% and 30% and even more preferably between 13% and 25%. Controlling the moisture content and the temperatures at the edge and core of the mixing strip makes it possible to substantially reduce the heating energy supplied by the heating systems, since the thermal energy that must be dissipated homogeneously in the mixing strip depends on said moisture content.

[0111] The duration of the mixing operation(s) depends on the size of the installation and in particular of the mixer 3.

[0112] According to an exemplary implementation, the method consists in step a), of using at least one grinder to shred and grind the straw into bales, said at least one grinder comprising adjustable shredding / grinding tools to define the shape and dimensional properties of the strands of defibrated straw obtained.

[0113] Mixers 3, 3a and 3b are advantageously rotating cylinders followed downstream by a drop cage.

[0114] According to an exemplary implementation, the binder material comprises a binder comprising thermofusible bi-component fibers, Polyester / Polyethylene fibers, Polyester / PBT fibers. These thermofusible bi-component fibers advantageously have a low melting point of approximately 110°C.

[0115] According to another example of implementation, the binder material comprises polylactic biopolymer fibers of the PLA / Co-PLA, PLA / PBS type obtained from cereals. These thermofusible bi-component fibers advantageously have a low melting point between 130°C and 164°C.

[0116] According to an exemplary implementation, the method consists of mixing the binder material, or the mixture of defibrated straw and the binder material, with one or more adjuvants comprising a fungicidal product with a proportion by mass relative to the total mass of the mixed products, of between 0.03% and 11% and preferably of between 0.5% and 4%.

[0117] According to another example of implementation, the method consists, after step f) and preferably after formatting the mixture in length and width, in spraying on each face of the mixing strip, one or more adjuvants comprising a fungicidal product with a proportion by mass relative to the total mass of the mixed products, of between 0.03% and 11% and preferably of between 0.5% and 4%. For example, reference may be made to Figure 1.

[0118] The length and width formatting of the mixing strip is carried out, for example, by a peripheral cutting operation.

[0119] According to another example of implementation, the adjuvants include a fire retardant product with a mass proportion relative to the total mass of the mixed products, between 24% and 72%.

[0120] According to another example of implementation, the fire-retardant product comprises a geopolymer in viscous or liquid form. An example of this is metakaolin.

[0121] According to an exemplary implementation, the method comprises a step of applying to at least one face of the insulating panel, a fire-retardant or flame-retardant coating, which has a thickness of at least 0.5 mm.

[0122] The invention also relates to a composite insulating panel comprising an insulating panel obtained according to the manufacturing method detailed above and onto which an additional fire-retardant panel is bonded.

[0123] The invention also relates to a prefabricated modular wooden structure for making a wall or a wall or for covering a wall of a building, on the exterior or interior side. Such a structure comprises at least one insulating panel obtained according to the manufacturing method detailed above.

[0124] The invention also relates to a mixed prefabricated modular structure made of wood and concrete for making a wall or for covering a wall of a building, on the outside or inside. Such a structure comprises at least one insulating panel obtained according to the manufacturing method detailed above. By way of example, the method according to the invention makes it possible to manufacture a semi-rigid insulating panel having a density of between 50 kg / m 3 and 150 kg / m 3 and preferably between 60 kg / m 3 and 100 kg / m 3 after cooling. An insulating panel with a density of between 50 kg / m 3 and 100 kg / m 3 will have predominantly thermal insulation properties whereas an insulating panel with a density of between 100 kg / m 3 and 150 kg / m3 will have predominantly fire resistance and sound insulation properties.

[0125] The insulating panels obtained using the process according to the invention can thus have very varied technical characteristics. With the same manufacturing process, it is possible to obtain panels suitable for different applications. Depending on these technical characteristics, the panel can be applied to a roof, a wall or a floor.

[0126] It is obvious that the present description is not limited to the examples explicitly described, but also includes other embodiments and implementations. Thus, a described technical feature, or a described method step, can be replaced by an equivalent technical feature, respectively an equivalent step, without departing from the scope of the present invention as defined by the claims.

Claims

Claims 1. A method for the continuous manufacture of an insulating panel based on cereal straw, characterized in that it comprises the steps: a) mechanically grinding the straw to obtain a defibrated straw whose strands have an average length of between 3 mm and 22 mm and preferably between 3 mm and 11 mm and whose average diameter is between 0.5 mm and 4.0 mm and preferably between 0.5 mm and 2.5 mm, b) using a mixer (3) and mixing the defibrated straw with a binder material introduced into the mixer (3) with a mass proportion of between 3% and 25% and preferably between 3% and 10% and more preferably between 3% and 9% relative to the total mass of the mixture, c) injecting compressed air into the mixture to homogenize said mixture, d) depositing the mixture on a conveyor, e) calibrating the thickness of the mixture to form a continuous strip of mixture of determined thickness,f) heating the mixing strip to bring it to and / or maintain it at a temperature of at least 90°C and preferably between 110°C and 150°C and more preferably between 110°C and 145°C, throughout the thickness of said mixing strip over a heating time d, c , g) cooling the insulating strip thus obtained to room temperature or to a temperature close to room temperature and calibrating the width and length of said insulating strip to form the insulating panel, h) packaging the insulating panel.

2. Method according to claim 1, characterized in that it consists in step a) of using at least one grinder to shred and grind the straw into bales, said at least one grinder comprising adjustable shredding / grinding tools to define the shape and size properties of the strands of defibrated straw obtained, said tools comprising knives and hammers in series.

3. Method according to claim 1 or 2, characterized in that it consists under the following: steps b), c) and d) using at least one mixer (3) of the rotating cylinder type, associated downstream, with a drop cage from which the conveyor is fed.

4. Method according to any one of claims 1 to 3, characterized in that it consists of filtering the defibrated straw obtained under a) to remove dust and other impurities in a proportion by mass of at least 2% and preferably at least 5% to 10% of the defibrated straw.

5. Method according to any one of claims 1 to 4, characterized in that the binder material comprises a thermofusible two-component binder chosen from two-components comprising polylactic biopolymer fibers of the PLA / Co-PLA, PLA / PBS type obtained from cereals.

6. Method according to any one of claims 1 to 4, characterized in that the binding material comprises a two-component hot-melt binder comprising Polyester / Polyethylene, Polyester / PBT fibers.

7. Method according to any one of claims 1 to 6, characterized in that it consists of mixing the binder material, or the mixture of defibrated straw and the binder material, with one or more adjuvants comprising a fungicidal product with a proportion by mass relative to the total mass of the mixed products, of between 0.03% and 11% and preferably of between 0.5% and 4%.

8. Method according to any one of claims 1 to 6, characterized in that it consists, after step f) and preferably after formatting the mixture in length and width, in spraying on each face of said mixture, one or more adjuvants comprising a fungicidal product with a proportion by mass relative to the total mass of the mixed products, of between 0.03% and 11% and preferably of between 0.5% and 4%.

9. Method according to any one of claims 1 to 8, characterized in that the adjuvants comprise a fire retardant product with a proportion of mass relative to the total mass of the mixed products, between 24% and 72%.

10. Method according to claim 5 or 6, characterized in that it comprises an operation of disentangling and aeration of the binding material prior to step b).

11. Method according to any one of claims 1 to 10, characterized in that step f) is implemented using on the one hand a high frequency or microwave heating system to heat the mixing strip in depth and on the other hand an additional heating system to heat the mixing strip at its free peripheral edges, said additional heating system comprising an infrared heating system.

12. Method according to any one of claims 1 to 11, characterized in that it consists of using at least one sensor and / or probe to measure the temperature at the edge of the mixing strip and using at least one sensor and / or probe to measure the core temperature of said mixing strip and continuously controlling the heating systems according to values ​​measured by said sensors and / or probes.

13. Method according to any one of claims 1 to 12, characterized in that it consists of using at least one sensor and / or probe to measure the humidity level of the mixture during step d) or e) and controlling the heating systems as a function of values ​​measured by said sensor and / or probe.

14. Semi-rigid insulating panel or insulating assembly, comprising at least one panel obtained by the manufacturing method according to any one of claims 1 to 13, said panel having a density of between 50 kg / m 3 and 150 kg / m 3 and preferably between 60 kg / m 3 and 100 kg / m 3 .

15. Prefabricated modular structure in wood or mixed concrete - wood to create a wall or to cover a wall of a building, exterior side or side interior, characterized in that it comprises at least one insulating panel manufactured according to the method according to any one of claims 1 to 13

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