Rigid insulating panel made of bonded wood fibers and its manufacturing process

Abstract

Rigid insulating panel made of bonded wood fibers and its manufacturing process. The present invention relates to a panel (11) formed of wood fibers (4) with a specific morphological distribution, having a density between 300 kg / m³ and 60 kg / m³, and a thickness between 330 mm and 8 mm. The binder connecting the wood fibers consists of a material resulting from the cross-linking, particularly by polymerization, of a two-component, isocyanate-free, preferably bio-based, aqueous thermosetting adhesive. Figure to be published with the abstract: Fig. 1

Description

Title of the invention: Rigid insulating panel made of bonded wood fibers and its manufacturing process

[0001] The present invention relates to the field of industrial manufacturing processes for building products, in particular insulating products, advantageously bio-based, and has as its objects a rigid insulating panel made of bonded wood fibers, as well as a manufacturing process for such a panel.

[0002] Historically, rigid wood fiber insulation panels were produced using a process known as the "wet process," quite similar to a papermaking process. Once the wood fibers were obtained after defibration, they were mixed in large vats of water (95% water by mass). The rigid bonds between the fibers were created by hydrogen bonds between the cellulose chains of the wood, or, where applicable, with the polar groups of an additive binder such as starch. These "wet process" methods were extremely energy-intensive. Indeed, they required a significant amount of energy to remove all the water from the wet fiber cake. The dryer was, in fact, the bottleneck in the production process. It was equipped with an elevator and various drying trays to optimize the entire line.This primary energy consumption worsened the environmental impact of wood fiber panel production, even though the bio-based nature of the wood and binder justified their commercial viability compared to equally high-performing, less expensive, but non-bio-based insulation materials.

[0003] New processes emerged around 1990 that allowed for the alternative production of such rigid wood fiber insulation panels, namely, the so-called "dry process," directly derived from the production processes of MDF (medium-density fiberboard). In this process, the wood fibers are dried immediately after defibration using a high-speed, airflow, flash tube dryer. Compared to the wet process, in which the wood / water ratio is only around 5% by mass, the dry process involves a much lower quantity of water, with the wood / water ratio of the drained fiber to be dried being around 75% to 25% moisture. With this lower moisture ratio, the water is no longer present in an "accessible" liquid form. It is, in fact, bound within the cellulose chains of the wood. The reduced quantity of water therefore no longer allows the fibers to felt.It is then no longer possible to generate a very large number of weak cohesive interactions, such as the previously described "hydrogen" bonds, since the fibers are no longer in a dispersed medium. A glue-type binder must then be used. To avoid formaldehyde emissions, the binder generally used is derived from the chemistry of [unspecified substances]. Polyurethanes, specifically those based on pMDI (polymer methylene diphenyl diisocyanate), are used. Binder activation is initiated by an external energy input; this energy activates the reaction of the isocyanate groups in the pMDI adhesive with the hydroxyl groups on the wood surface. The thermodynamic activation barrier of the adhesive allows the wood fibers to be bonded, and the resulting slab of bonded fibers to be shaped to the desired thickness, with the adhesive only being activated once the final panel shape is achieved. This activation is controlled by the addition of steam during the continuous pressing of the slab of bonded fibers.Water vapor reacts with a portion of the adhesive (R-NCO₃ + HO-H) to initiate an exothermic reaction forming amines and carbon dioxide. This heat, generated at the core of the insulating fiber cake, significantly contributes to activating the desired reaction: pMDI adhesive + wood hydroxyl group. Additionally, the reaction with water generates the formation of amines and, through successive reactions, polymerization of the binder. Since the residence time in the press is only a few tens of seconds, the activation must be particularly efficient.

[0004] The chemical reactions involved are shown below: H CO1Î + RN-OO JS R~N”C“O + HZO -----* R~NH’ GH -----* k-NHs * R-NH’ HN-R carbamic acid amine urea 9 RNC-Û + R'-OH urethane

[0005] The use of isocyanate adhesives containing free monomers in this "dry process" remains a significant industrial challenge for operators. The REACH regulation highlights the sensitizing and potentially carcinogenic nature of isocyanate monomers, leading to the implementation of enhanced training and measures concerning personal and collective protective equipment. For information purposes, isocyanate adhesives commonly used for the dry process production of rigid wood fiber insulation panels contain between 30% and 50% free monomers. The use of pMDI also degrades the environmental performance of panels produced by the dry process. Indeed, most pMDI binder production technologies are currently petroleum-based.

[0006] The main objective of the present invention is to overcome the drawbacks of the aforementioned prior art by proposing a rigid insulating panel that can be manufactured in a more environmentally friendly way, while exhibiting mechanical, thermal insulation, reaction and fire resistance, and water absorption properties that are at least equivalent to those of panels obtained by the aforementioned known processes, without using substances meeting SVHC criteria (substances of very high concern). Furthermore, the invention also aims to propose a manufacturing process for such a panel that overcomes the limitations of the two aforementioned known processes, by offering a third manufacturing solution for rigid wood fiber insulation panels that is, on the one hand, less energy-intensive than the "wet process" and, on the other hand, more respectful of human health and the environment than the traditionally known "dry process," and which also prioritizes sustainable resources.

[0007] To this end, the invention relates to a rigid insulating panel made of wood fibers bonded with an adhesive, said panel being formed of wood fibers that meet the following morphological description or distribution: the median length of the wood fibers is between 500 and 5000 microns, advantageously between 1500 and 4000 microns, and preferably between 2000 and 3000 microns, and the median diameter of the wood fibers is between 40 and 100 microns, advantageously between 50 and 90 microns, preferably between 60 and 70 microns, said panel having: - a unit weight between 300 kg / m³ and 60 kg / m³, advantageously between 250 kg / m³ and 70 kg / m³, preferably between 220 kg / m³ and 80 kg / m³,

[0008] - a thickness between 330 mm and 8 mm, advantageously between 320 mm and 20 mm, preferably between 300 mm and 30 mm, and the binder connecting the wood fibers together consisting of a material corresponding to the reaction product of a two-component aqueous composition of glue or thermosetting resin, free of isocyanate, preferably bio-based.

[0009] The invention also relates to a method for manufacturing such a panel and to an industrial installation, of the type production line, for implementing said method.

[0010] The invention will be better understood from the following description, which relates to preferred embodiments, given by way of non-limiting examples, and explained with reference to the accompanying schematic drawings, in which:

[0011] [Fig. 1] schematically represents an example of an installation in the form of a production line for implementing the manufacturing process according to the invention, with an indication of the main steps of said process, with a second pressing station according to a first embodiment, and,

[0012] [Fig.2] schematically represents another example of embodiment, according to a preferred variant, of a second pressing station for carrying out step h) of the process which can be part of the installation of [Fig.1].

[0013] The invention relates to a rigid insulating panel (11) made of wood fibers (4) bonded by an adhesive,

[0014] said panel (11) being formed of wood fibers (4) which correspond to the following morphological description or distribution: the median length of the wood fibers is between 500 and 5000 microns, advantageously between 1500 and 4000 microns, and preferably between 2000 and 3000 microns, and, the median diameter of the wood fibers is between 40 and 100 microns, advantageously between 50 and 90 microns, preferably between 60 and 70 microns,

[0015] said panel (11) presenting:

[0016] - a volumetric weight between 300 kg / m3 and 60 kg / m3, advantageously between 250 kg / m3 and 70 kg / m3, preferably between 220 kg / m3 and 80 kg / m3,

[0017] - a thickness between 330 mm and 8 mm, advantageously between 320 mm and 20 mm, preferably between 300 mm and 30 mm, and the binder connecting the wood fibers together, consisting of a material corresponding to the product of a reaction of a two-component aqueous composition of glue or thermosetting resin, free of isocyanate. This glue composition is preferably bio-based.

[0018] Thanks to these provisions, the invention makes it possible to achieve the main objective set, namely, to provide a rigid insulating panel that can be manufactured in a more virtuous way, while exhibiting mechanical, thermal insulation, reaction and fire resistance and water absorption properties that are at least equivalent to those of the panels obtained by the known processes mentioned above.

[0019] Preferably, the panel (11) comprises between 15% and 3% by weight of binder relative to the total weight of the panel, advantageously between 12% and 4%, preferably between 10% and 4.5%, most preferably between 9% and 5%.

[0020] In accordance with an advantageous embodiment, corresponding to a panel (11) substantially made entirely from bio-based materials, the composition of the glue or thermosetting resin is preferably based on:

[0021] - of at least one aromatic compound Al comprising at least one aromatic ring bearing at least two functions, one of these functions being an aldehyde function or a hydroxymethyl function, the other being an aldehyde function or a hydroxymethyl function;

[0022] - of at least one aromatic phenol compound A2 bearing at least one nucleus aromatic bearing at least two hydroxyl functions, the latter being in meta position relative to each other, the two ortho positions of at least one of the hydroxyl functions being unsubstituted.

[0023] Thus, according to this embodiment of the invention, it is the aromatic ring which carries the hydroxymethyl functions or the hydroxymethyl and aldehyde functions and the compound Al corresponds to the general formula (I):

[0024] B-Ar-C (I) where Ar represents an aromatic ring and B, C represent respectively CHO or ch2oh.

[0025] The aromatic ring is advantageously a 5- or 6-membered ring, comprising, as members, carbon atoms and optionally one or more heteroatoms, in particular nitrogen, oxygen, or sulfur atoms, possibly oxidized as N-oxide or S-oxide. In one embodiment, the aromatic ring comprises 0, 1, or 2 heteroatoms. The remainder of the aromatic ring may or may not be substituted.

[0026] The aromatic ring can bear 0, 1 or 2 aldehyde functions, advantageously 0 or 1 aldehyde function.

[0027] The aromatic ring can bear 1, 2 or 3 hydroxymethyl functions, advantageously 1 or 2 hydroxymethyl functions.

[0028] In addition, the aromatic ring can also carry 0, 1 or 2 other function(s), in particular hydroxyl.

[0029] In the embodiment in which the aromatic ring is a 6-membered ring, the B and hydroxymethyl functions are advantageously in meta or para positions relative to each other.

[0030] In the embodiment in which the aromatic ring is a 5-membered ring, the ring may comprise one or more heteroatoms, in particular nitrogen, oxygen, or sulfur atoms, optionally oxidized as N-oxide or S-oxide. Advantageously, the aromatic ring comprises 1 or 2 heteroatoms, preferably 1 heteroatom.

[0031] In this embodiment in which the aromatic ring is a 5-membered ring, at least one of the following three conditions is met: - the aromatic ring comprises 0 or only one aldehyde function; - the aromatic nucleus includes one or two hydroxymethyl functions; - the aromatic nucleus comprises one or two aldehyde functions.

[0032] Advantageously, apart from the aldehyde and hydroxymethyl functions, the rest of the aromatic ring is not substituted.

[0033] Advantageously, in a first case, the aromatic core comprises:

[0034] - a single aldehyde function;

[0035] - a single hydroxymethyl function;

[0036] - apart from the aldehyde and hydroxymethyl functions, the rest of the aromatic ring is not not substituted.

[0037] Advantageously, in a second case, the aromatic core comprises:

[0038] - two hydroxymethyl functions;

[0039] - apart from the hydroxymethyl functions, the rest of the aromatic ring is not substituted.

[0040] Advantageously, in a third case, the aromatic core comprises:

[0041] - two aldehyde functions;

[0042] - apart from the aldehyde functions, the rest of the aromatic ring is not substituted.

[0043] Advantageously, the aromatic compound Al corresponds to the general formula (II):

[0044] in which B and C represent respectively CHO or CH2OH, X represents O, NRi, NO, S, SO, SO2, SR2R3; Rb R2, R3 each represent, independently of each other, a hydrogen, an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group.

[0045] 5-(Hydroxymethyl)furfural (Il'al) is an aldehyde particularly well-suited as an Al compound, given that this organic compound can be easily extracted from renewable resources. Indeed, it is derived in particular from the dehydration of certain sugars such as fructose, glucose, sucrose, cellulose, and rinulin.

[0046] Preferably, when the thermosetting glue or resin is based on polyphenol and one or more compounds of formula (I), the composition is free of formaldehyde (except for possible traces).

[0047] Regarding the second compound A2, and in accordance with a possible embodiment of the invention, one of the aromatic rings of the aromatic polyphenol carries three hydroxyl functions in meta positions relative to each other.

[0048] Preferably, the two ortho positions of each hydroxyl function of at least one aromatic ring are unsubstituted.

[0049] Even more preferably, the two ortho positions of each hydroxyl function of each aromatic ring are unsubstituted.

[0050] Even more preferably, the remainder of each of the aromatic rings is unsubstituted. This means that the other carbon atoms of the remainder of each aromatic ring (those other than the carbon atoms bearing the hydroxyl functions or bearing the group linking the aromatic rings together) bear a single hydrogen atom.

[0051] Advantageously, the aromatic ring bearing at least two hydroxyl functions in meta positions relative to each other, the two ortho positions of at least one of the hydroxyl functions being unsubstituted, is a benzene ring.

[0052] According to a highly preferred embodiment of the invention, the aromatic polyphenol is selected from the group consisting of resorcinol, phloroglucinol, 2,2',4,4'-tetrahydroxydiphenyl sulfide, 2,2',4,4'-tetrahydroxybenzophenone, and mixtures of these compounds.

[0053] According to an advantageous practical aspect, and to arrive at a manufacturing process for the panel (11) that is easily applicable industrially, the quantity of resin or glue is at least 30%, preferably at least 40% by weight of dry extract of resin or glue relative to the total weight of the aqueous adhesive composition.

[0054] Advantageously, for the short fiber fraction, the length fractile at 10% population is between 150 and 700 microns, advantageously between 300 and 600 microns, and preferably between 400 and 500 microns. For the long fiber fraction, the length fractile at 90% population is between 2500 and 10000 microns, advantageously between 4000 and 8000 microns, and preferably between 5000 and 6000 microns.

[0055] Advantageously, for the fraction of fibers with smaller diameters, the diameter fractile at 10% population is between 20 and 50 microns, advantageously between 30 and 45 microns, preferably between 35 and 40 microns. For the fraction of fibers with larger diameters, the diameter fractile at 90% is between 100 and 400 microns, advantageously between 150 and 300 microns, preferably between 200 and 300 microns.

[0056] The invention also relates to a method for manufacturing rigid insulating wood fiber panels (4), which comprises at least the following steps:

[0057] - a) supply of lignocellulosic raw material (2), namely in particular wood in the form of flakes or similar fragments, possibly originating at least partially from recycled materials or waste,

[0058] - b) shredding and defibration of the lignocellulosic raw material, to obtain wood fibers (4) whose morphological distribution is such that the median length of said fibers is between 500 and 5000 microns, advantageously between 1500 and 4000 microns, and preferably between 2000 and 3000 microns and that the median diameter of said wood fibers is between 40 and 100 microns, advantageously between 50 and 90 microns, preferably between 60 and 70 microns,

[0059] - c) optionally, drying the wood fibres (4) produced in step b), in particular if they are not noticeably dry,

[0060] - d) impregnation of dried or substantially dry wood fibres (4), for example in a mixer, gluing tower or equivalent device (5), with a aqueous adhesive composition of the type two-component aqueous composition of glue or thermosetting resin, preferably based on two aromatic compounds (Al and A2), and free of isocyanate,

[0061] - e) conveying the impregnated fibers (4) to a conforming system fibres in a cake or mat (7), this transport step contributing where appropriate to the completion of the sizing and to obtaining a substantially homogeneous distribution of the glue composition on the fibres (4),

[0062] - f) conformation of the impregnated fibers (4) in the form of a cake or mat (7),

[0063] - g) first pressing phase of the cake or mat (7), to compact the latter, but without activating the glue compound,

[0064] - h) second pressing phase of the pre-compacted cake or mat (7) with setting to the desired thickness and polymerization (preferably to crosslinking of the thermosetting adhesive composition under the action of either at least one unidirectional heat flow, or two mutually opposed heat flows, passing through the thickness of the cake or mat (7) of impregnated fibers (4), so as to produce a binder connecting said fibers (4), said heat flows being optionally accompanied by vapor, incorporating vapor or corresponding to vapor flows,

[0065] - i) cutting the cake or mat (7) into panels (11), to the desired length, and possible machining of the cut panels,

[0066] - j) possible conditioning of the finished panels (11).

[0067] Thanks to the above combination of successive operating steps, the invention also makes it possible to achieve the stated objective in terms of the process. Drying can be implemented either optionally, where appropriate in conjunction with a device for measuring the moisture content of the fibers to determine whether they are sufficiently dry for subsequent steps in the manufacturing process, or systematically.

[0068] More specifically regarding the description or morphological distribution of the wood fibers (4) at the end of step b), it may also be provided that:

[0069] - for the fraction of short fibers (4), the length fractile at 10% of The population size is between 150 and 700 microns, advantageously between 300 and 600 microns, and preferably between 400 and 500 microns.

[0070] - for the fraction of long fibers (4), the length fractile at 90% of population is between 2500 and 10000 microns, advantageously between 4000 and 8000 microns, and preferably between 5000 and 6000 microns, and / or that

[0071] - for the fraction of fibers (4) with smaller diameters, the diameter fractile at 10% of the population is between 20 and 50 microns, advantageously between 30 and 45 microns, preferentially between 35 and 40 microns.

[0072] - for the fraction of fibers (4) with larger diameters, the diameter fractile at 90% is between 100 and 400 microns, advantageously between 150 and 300 microns, preferably between 200 and 300 microns.

[0073] Regarding step h), depending on the desired performance in terms of manufacturing and / or properties of the resulting panels (11), the vapor flow through the cake or mat (7) pre-compacted in step g), and activating the polymerization of the adhesive composition (to produce the binder), can be unidirectional (from bottom to top, or from top to bottom), or bidirectional. In the latter case, two vapor flows pass through the thickness of the cake or mat (7) in opposite directions. If necessary, the position of the opposing vapor flows can be slightly offset in space to ensure complete passage through the cake for each of them.

[0074] The polymerization, preferably to the point of cross-linking, of the adhesive or thermosetting resin composition impregnating the mat or cake (7) is advantageously achieved by the combined effect of heat input and steam injection. To this end, a second pressing (or final thicknessing) station, as shown in [Fig. 2], can be implemented for carrying out step h). This station (9) is in the form of an oven through which a conveyor belt (13) passes, transporting the mat or cake (7) exiting the first pressing station (8). This oven comprises two perforated lower and upper hot plates (14, 14'), through the openings of which at least one stream of steam (15) can be injected into the fiber cake or mat (7), which circulates between said plates (14, 14') transported by said belt (13).Alternatively, two opposing and slightly offset steam streams can be implemented for more efficient and homogeneous action.

[0075] Of course, at the end of the process, in addition to being brought to the desired length, the panels (11) obtained can also possibly be cut lengthwise to be brought to a desired width, if necessary.

[0076] In an advantageous embodiment of the process, allowing the stated objective to be achieved in an optimized manner, particularly in terms of environmental criteria, the aqueous composition of thermosetting adhesive from steps d) to h) is obtained by mixing:

[0077] - of an aromatic compound Al comprising at least one aromatic ring bearing of at least two functional groups, one of which is an aldehyde or hydroxymethyl group, and the other is an aldehyde or hydroxymethyl group; and

[0078] - of an aromatic phenol compound A2 bearing at least one aromatic ring carrying at least two hydroxyl groups, these are in the meta position relative to each other, with the two ortho positions of at least one of the hydroxyl functions being unsubstituted,

[0079] in a basic solvent preferably having a pH between 8 and 10, more preferably between 8.5 and 9.5.

[0080] If necessary, the aqueous composition of the thermosetting adhesive further comprises a compound of the urea type or similar, this compound being present at a mass percentage of the dry extract of the composition of between 0.002 and 0.250 (between 0.2% and 25% by weight). This optional provision may improve the cold stability and the shelf life of the resulting binder.

[0081] In accordance with a first embodiment, shown in [Fig.1], the process provides that the operations of steps f) to i) at least are carried out in continuous flow by scrolling a monolithic mat of glued wood fibers.

[0082] In accordance with a second embodiment, the process provides that the operations of steps f) to i) are carried out sequentially and discontinuously on successive cakes.

[0083] Advantageously, the defibration of the lignocellulosic raw material in step b) is carried out under steam pressure, for example in a defibrator, while the drying in step c) is advantageously carried out in a hot air tube dryer. This drying is optional: its actual execution and intensity depend on the moisture content of the wood fibers (4) at the end of step b). Preferably, these fibers have a moisture content of between 6% and 8% by mass before being sizing in step d).

[0084] In accordance with a feature ensuring efficient activation of the glue composition and good productivity of the process, the second pressing phase of step h) is carried out with a temperature of at least 105°C, advantageously with a temperature between 110°C and 160°C, preferably between 115°C and 155°C, at the level of the mat or cake of glued wood fibers, the hot air passing through the cake or mat of wood fibers having a relative humidity of the maximum of 70%, advantageously between 10% and 70%, preferably between 10% and 50%.

[0085] In addition, preferably, this second pressing phase of step h) is carried out with a dew point of at least 90°C, advantageously between 90°C and 96°C, preferably between 92°C and 96°C.

[0086] In order to produce panels (11) exhibiting the mechanical and physical properties required in relation to their use, the second pressing phase of step h) is configured in such a way that the unit weight of the finished panels is between 60 kg / m3 and 300 kg / m3, advantageously between 70 kg / m3 and 250 kg / m3, preferably between 80 kg / m3 and 220 kg / m3.

[0087] Furthermore, to obtain panels (11) dimensioned for their application in the building, the second pressing phase of step h) is configured in such a way that the thickness of the finished panels is between 8 mm and 330 mm, advantageously between 20 mm and 320 mm, preferably between 30 mm and 300 mm.

[0088] In relation to the aforementioned types of glues and in order to meet the criteria relating to the mechanical and physical properties required for the resulting panels (11), the quantity of aqueous composition of glue or binder mixed with the wood fibers during step d) is adjusted in such a way that the finished panels comprise between 3% and 15% by weight of polymerized binder or glue or, relative to the total weight of said panels, advantageously between 4% and 12%, preferably between 4.5% and 10%, most preferably between 5% and 9%.

[0089] In accordance with an advantageous practical embodiment of the process, the fiber cake impregnated with 6% to 9% by weight of aqueous composition of glue or resin described below is subjected in step h) to a steam flow with a dew point of 92°C to 95°C for 15 to 60 s, combined with or followed by a passage, for 60 to 120 s, between plates at a temperature of 110°C to 130°C.

[0090] Test specimens corresponding to reduced-size versions of panels (11) according to the invention were made in the laboratory to test the resistance to compression and tension.

[0091] After preparation of the aqueous adhesive composition, the latter was sprayed onto a cake of wood fibers (4), then this cake was subjected to a heating operation by a hot press.

[0092] These laboratory tests demonstrate that the compression and tensile performance of the resin-based insulation panels according to the invention as described above is at least equivalent to those of existing polyurethane resin-based elements or wood fiber panels, particularly those of the applicant.

[0093] To perform comparative tests, three aqueous adhesive compositions were prepared, two according to the embodiment of the invention (hereafter referred to as C-2 and C-3), and one not according to the invention (control composition, hereafter referred to as Cl). Their formulations (expressed as percentages by weight) are presented in Table 1 below. The quantities listed in this table are those of the constituents in their dry state, converted to a total of 100 parts by weight of aqueous adhesive composition (i.e., the constituents and water).

[0094] The adhesive composition Cl is a control composition based on 4,4'-methylenediphenyl diisocyanate (MDI).

[0095] Adhesive compositions C-2 and C-3 are aqueous adhesive compositions according to the embodiment of the invention based on 5-(hydroxymethyl)-furfural and phloroglucinol.

[0096] Protocol for preparing the aqueous adhesive composition:

[0097] Water and sodium hydroxide are introduced into a 250 mL flask equipped with a mechanical stirring system. The mixture is stirred for 1 to 10 minutes to homogenize it (for example, at 250 rpm) until it reaches 35°C. Then, compound A2 (for example, phloroglucinol) is added and the mixture is stirred for, for example, 1 to 60 minutes to homogenize it (for example, at 250 rpm). Next, aromatic compound A1 (for example, 5-hydroxymethylfufural) is added and the mixture is stirred for 25 to 45 minutes at 50°C, then cooled to the storage temperature. This yields a mixture of the aqueous adhesive composition according to the embodiment of the invention.

[0098] At the end of this time the aqueous adhesive composition according to the embodiment of the invention is ready to be used.

[0099] [Tables 1] 1. Adhesive compositions Cl C-2 C-3 5-(hydroxymethyl)furfural (1) - 16 18 Phloroglucinol (2) - 17 20 MDI 100 - - Sodium hydroxide (3) - 3 4 Total weight of dry extract of adhesive composition NC 36 42 Weight of water 0 64 58 Total 100.0 100.0 100.0 1. HMF (from the Aldrich company; purity > 99%); 2. Phloroglucinol (from Alfa Aesar company; 99% purity); 3. Sodium hydroxide (from the Aldrich company; diluted to 30%).

[0100] Resin adhesion test on the element

[0101] The quality of the bond between the fibrous materials is determined by a test in which the force required to separate these elements by destroying the bond joining these elements is measured.

[0102] More specifically, each test specimen is obtained by mixing 350 g of fiber and 16 g of resin for Cl (reference PU) for 2 min, and for C-2, 350 g of fiber and 40 g of resin are mixed and spray-injected at 20 °C. The heating process can be, for example, by mat with a 4 cm gap via a heated press between 80°C and 160°C for 60 seconds to 1 hour or by microwave cooking.

[0103] The percentage of resin is then indicated; the control composition Cl has a resin content of 4.5% for 95.5% fibers by weighing the test specimen.

[0104] Compression and tensile test of the element

[0105] The evaluation results of the elements are obtained by subjecting them to compression.

[0106] Wood fiber test specimens with a density of 120 kg / m³ are cut to dimensions of 20 x 20 x 4 cm and then placed between two parallel compression plates of a tensile testing machine. A constant displacement rate of d / 10 mm per minute is applied with a tolerance of ± 25%, where d is the initial thickness of the specimen, i.e., 4 cm in this case. The NF EN 826 standard of May 2013 allows the compressive strength value to be determined, which will be obtained by reaching a relative deformation of 45% and preferably 50%.

[0107] Furthermore, in this same standard, the tensile strength is determined.

[0108] An acceptable result would be tensile strength values ​​greater than 3 kPa and a good result would be tensile strength values ​​greater than 5 kPa.

[0109] NA results are not available.

[0110] The results of the tests carried out on the three aforementioned test specimens are summarized in Table 2 below. [YES] [Tables 2] Adhesive compositions Cl C-2 C-3 % of resin in the element 4.5 4.5 6 Mechanical characteristics Compression (%) 50 55 46 Tensile strength (kPa) 5 3 7

[0112] It is observed that the elements made with adhesive compositions C-2 and C-3 according to the embodiment of the invention exhibit, in particular, an adhesive performance, as demonstrated by the tensile test, equivalent to or even superior to that of element CL

[0113] Regarding compression characteristics, the elements made with adhesive compositions C-2 and C-3 according to the embodiment of the invention also exhibit performance equivalent to composition CL

[0114] Thus, the test specimens produced in accordance with the invention exhibit technical and mechanical performance similar to that of panels of the same type incorporating traditional binders, without using substances meeting the SVHC criteria (substances of very high concern), and being advantageously based on bio-based substances.

[0115] In conclusion, the results of these various tests clearly demonstrate that the panels according to the invention incorporating fiber-bonding adhesive compositions as described above constitute an interesting alternative to panels incorporating conventional adhesive compositions, by eliminating the extremely concerning molecules.

[0116] In addition, panels (11), in accordance with the characteristics of the invention and manufactured according to the process described above, correspond in particular to rigid self-supporting panels, both insulating according to the European standard NF EN 13171, and able to also form rigid under-roof screens according to the European standard NF EN 14964.

[0117] More specifically, the panels (11) manufactured according to the invention advantageously meet, for example, the following criteria: These panels have dimensions that can be handled on a roofing or ventilated facade construction site (2500 x 770 mm; or 1880 x 610 mm). They are edge-machined to have a tongue and groove joint on all four sides, ensuring the continuity of the waterproofing function of the structure once installed. The density of these panels can range from 165 kg / m³ to 200 kg / m³. The thermal conductivities of these panels range from 0.43 to 0.44 W / (m*K), measured according to NF EN 12667. The compressive strengths at 10% deformation can range from 100 to 200 kPa (according to NF EN 826). Perpendicular tensile strengths can range from 10 to 30 kPa (according to NF EN 1607). Their flexural performance, measured according to NF EN 310, is at least 400 kPa for panel thicknesses greater than 36 mm.For thicknesses of 35 mm, the minimum flexural strength is 900 kPa. These panels, intended for exterior use, are hydrophobic throughout, guaranteeing that capillary absorption is always less than 1 kg of water per square meter (according to NF EN 1609). In addition, these panels exhibit thickness swelling of less than 6% after 2 hours of total immersion (according to NF EN 317). These thickness swelling and flexural strength performance characteristics allow for the definition of an SB.E panel classification (according to NF EN 622-4), an essential element for recognition as a rigid underlayment according to standard EN 14964. The fire reaction of this type of rigid panel is classified as E, according to standard EN 13501.

[0118] Panels (1) incorporating a fiber-binding adhesive obtained by the reaction of 5-(hydroxymethyl)-furfural and phloroglucinol, with a binder concentration by weight in the panels between 6% and 9%, have been manufactured. The table below provides, for these panels (11) in accordance with this embodiment preferred of the invention, but of different densities, and obtained by the process described, the main characteristics and properties of the panels concerned:

[0119] [Tables3] Density (Kg / m3) 110kg / m3 115 kg / m3 140 kg / m3 195-200 kg / m3 Thickness (mm) 30 - 240 40 - 240 40-80 30 -80 Thermal conductivity cf. EN 12667 0.038 W / (m*K) 0.049 W / (m*K) 0.042 W / (m*K) 0.044 W / (m*K) Compression Resistance at 10% cf. EN 826 50kPa 50kPa 100 kPa 200 kPa Tensile resistance perpendicular action cf. EN 1607 2.5 kPa 7.5 kPa lOkPa 30kPa Short term ca pillary water return cf. EN 1609 < WS2 kg / m2 < WS1 kg / m2 < WS1 kg / m2 < WS1 kg / m2 Swelling cf. EN 317 / / <6% <6% Fission resistance cf. EN 310 / / > 400 kPa > 400 kPa Water impermeability cf. EN 12467 / / No liquid water penetration No liquid water penetration Euroclass cf. EN 13501-1 EEEE

[0120] It can be noted that optionally and for specific applications, substances with targeted properties (for example, antifungal and / or flame retardant additives, urea) can be added to the aqueous adhesive composition intended to form the binder.

[0121] Finally, the invention also relates to an installation for setting up the process for manufacturing a panel as described above, represented schematically [Fig.1].

[0122] This installation essentially comprises a station (1) for grinding and defibrating lignocellulosic raw materials (2), a station (3) for progressively drying the wood fibers (4) from station (1), a station (5) for sizing the dried fibers (4), for example of the mixer, sizing tower or similar type, a station (6) for conveying and shaping the sizing fibers (4) into a cake or mat (7), a first station (8) for pressing the cake or mat (7), called the pre-pressing station, a second pressing station (9), called the final pressing and binder polymerization station, with application of at least one heat flow through the cake or mat (7), a station (10) for cutting the panels (11), with possible machining, and a station (12) for packaging the resulting panels (11), these stations (1, 3, 5, 8, 9, 10, 12) being arranged in series to form a production line.The drying station can be activated optionally, depending on the moisture content of the fibers passing through it.

[0123] Of course, the invention is not limited to the embodiments described and shown in the accompanying drawings. Modifications remain possible, particularly with regard to the composition of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

Demands

1. Rigid insulating panel (11) made of wood fibers (4) bonded with an adhesive, said panel (11) being formed of wood fibers (4) conforming to the following description or morphological distribution: the median length of the wood fibers is between 500 and 5000 microns, advantageously between 1500 and 4000 microns, and preferably between 2000 and 3000 microns, and the median diameter of the wood fibers is between 40 and 100 microns, advantageously between 50 and 90 microns, preferably between 60 and 70 microns, said panel (11) having: - a density between 300 kg / m³ and 60 kg / m³, advantageously between 250 kg / m³ and 70 kg / m³, preferably between 220 kg / m³ and 80 kg / m³, - a thickness between 330 mm and 8 mm, advantageously between 320 mm and 20 mm, preferably between 300 mm and 30 mm,and the binder connecting the wood fibers (4) together, consisting of a material corresponding to the reaction product of a two-component aqueous composition of glue or thermosetting resin, and free of isocyanate, preferably bio-based.

2. Panel according to claim 1, characterized in that it comprises between 15% and 3% by weight of binder relative to the total weight of the panel, advantageously between 12% and 4%, preferably between 10% and 4.5%, most preferably between 9% and 5%.

3. Panel according to any one of claims 1 and 2, characterized in that the composition of glue or thermosetting resin is based on: - at least one aromatic compound Al comprising at least one aromatic ring bearing at least two functions, one of these functions being an aldehyde or a hydroxymethyl function, the other being an aldehyde or a hydroxymethyl function; - at least one aromatic phenol compound A2 bearing at least one aromatic ring bearing at least two hydroxyl functions, the latter being in meta position relative to each other, the two ortho positions of at least one of the hydroxyl functions being unsubstituted.

4. Panel according to claim 3, characterized in that the aromatic compound Al responds to the general formula (II): "X. -J a~<' / / 'c (il) in which B and C represent respectively CHO or CH2OH, X represents O, NRb NO, S, SO, SO2, SR2R3; Rb R2, R3 each represent, independently of each other, a hydrogen, an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group.

5. Panel according to claim 2 or 3, characterized in that the compound Al is 5-(hydroxymethyl)furfural.

6. Panel according to any one of claims 1 to 5, characterized in that compound A2 comprises an aromatic polyphenol aromatic core which is bearing three hydroxyl functions in meta positions relative to each other.

7. Panel according to claim 6, characterized in that compound A2 is selected from the group consisting of resorcinol, phloroglucinol, 2,2',4,4'-tetrahydroxydiphenyl sulfide, 2,2',4,4'-tetrahydroxybenzophenone and mixtures of these compounds.

8. Panel according to any one of claims 1 to 7, characterized in that the quantity of resin is at least 30%, preferably at least 40% by weight of dry extract of resin relative to the total weight of the aqueous adhesive composition.

9. A method for manufacturing a rigid wood fiber insulating panel according to any one of claims 1 to 8, said method comprising at least the following successive steps: - a) supplying lignocellulosic raw material (2), namely in particular wood in the form of chips or similar fragments, possibly originating at least partially from recycled materials or waste, - b) shredding and defibrating the lignocellulosic raw material, to obtain wood fibers (4) having a morphological distribution such that the median length of said fibers is between 500 and 5000 microns, advantageously between 1500 and 4000 microns, and preferably between 2000 and 3000 microns.

10. microns and that the median diameter of said wood fibers is between 40 and 100 microns, advantageously between 50 and 90 microns, preferably between 60 and 70 microns, - c) optionally, drying the wood fibers (4) produced in step b), in particular if they are not substantially dry, - d) impregnation of the dried or substantially dry wood fibers (4), for example in a mixer, gluing tower or equivalent device (5), with an aqueous adhesive composition of the type two-component aqueous composition of glue or thermosetting resin, preferably based on two aromatic compounds (Al and A2), and free of isocyanate, - e) conveying the impregnated fibres (4) to a fibre molding system into a cake or a mat (7), this transport step contributing where appropriate to the completion of the sizing and to obtaining a substantially homogeneous distribution of the glue composition on the fibres (4), - f) conformation of the impregnated fibres (4) in the form of a cake or mat (7), - g) first pressing phase of the cake or mat (7), to compact the latter, but without activating the glue composition, - h) second pressing phase of the pre-compacted cake or mat (7) with setting to the desired thickness and polymerization of the thermosetting glue composition under the action of either at least one unidirectional heat flow, or two mutually opposed heat flows, passing through the thickness of the cake or mat (7) of impregnated fibers (4), so as to produce a binder linking said fibers (4), said heat flows being possibly accompanied by vapor, incorporating vapor or corresponding to vapor flows, - i) cutting of the cake or mat (7) into panels (11), to the desired length, and possible machining of the cut panels, - j) possible packaging of the finished panels (11). A manufacturing process according to claim 9, characterized in that the aqueous composition of glue or thermosetting resin in steps d) to h) is obtained by mixing: - of an aromatic compound Al comprising at least one aromatic ring bearing at least two functional groups, one of these groups being an aldehyde or a hydroxymethyl group, the other being an aldehyde or a hydroxymethyl group; and - of an aromatic phenol compound A2 bearing at least one aromatic ring bearing at least two hydroxyl functions, the latter being in meta position relative to each other, the two ortho positions of at least one of the hydroxyl functions being unsubstituted, in a basic solvent preferably having a pH between 8 and 10, more preferably between 8.5 and 9.

5.

11. A manufacturing process according to claim 10, characterized in that the aqueous composition of thermosetting glue further comprises a compound of the urea type or similar, this compound being present at a mass percentage of dry extract of the composition between 0.002 and 0.

250.

12. A manufacturing method according to any one of claims 9 to 11, characterized in that the operations of steps f) to i) at least are carried out in continuous flow by scrolling a monolithic mat of glued wood fibers.

13. A manufacturing method according to any one of claims 9 to 11, characterized in that the operations of steps f) to i) are carried out sequentially and discontinuously on successive cakes.

14. A manufacturing process according to any one of claims 9 to 13, characterized in that the defibration of the lignocellulosic raw material in step b) is carried out under steam pressure, for example in a defibrator, the drying in step c) being advantageously carried out in a hot air tube dryer.

15. A manufacturing process according to any one of claims 9 to 14, characterized in that the second pressing phase of step h) is carried out with a temperature of at least 105°C, advantageously with a temperature between 110°C and 160°C, preferably between 115°C and 155°C, at the level of the mat or cake of glued wood fibers, the hot air passing through the cake or mat of wood fibers having a relative humidity of no more than 70%, advantageously between 10% and 70%, preferably between 10% and 50%.

16. A manufacturing process according to any one of claims 9 to 15, characterized in that the second pressing phase of step h) is carried out with a dew point of at least 90°C, advantageously between 90°C and 96°C, preferably between 92°C and 96°C.

17. A manufacturing process according to any one of claims 9 to 16, characterized in that the second pressing phase of step h) is configured in such a way that the unit weight of the finished panels is between 60 kg / m3 and 300 kg / m3, advantageously between 70 kg / m3 and 250 kg / m3, preferably between 80 kg / m3 and 220 kg / m3.

18. A manufacturing method according to any one of claims 9 to 17, characterized in that the second pressing phase of step h) is configured such that the thickness of the finished panels is between 8 mm and 330 mm, advantageously between 20 mm and 320 mm, preferably between 30 mm and 300 mm.

19. A manufacturing process according to any one of claims 9 to 18, characterized in that the quantity of glue or binder mixed with the wood fibers during step d) is controlled in such a way that the finished panels comprise between 3% and 15% by weight of active or crosslinked binder or glue relative to the total weight of said panels, advantageously between 4% and 12%, preferably between 4.5% and 10%, most preferably between 5% and 9%.

20. A manufacturing process according to any one of claims 9 to 19, characterized in that the fiber cake impregnated with 6% to 9% by weight of glue composition according to any one of claims 3 to 8 is subjected in step h) to a steam flow with a dew point of 92°C to 95°C for 15 to 60 s, combined with or followed by a passage, for 60 to 120 s, between plates at a temperature of 110°C to 130°C.

21. An installation for carrying out the process according to any one of claims 9 to 20, for manufacturing a panel according to any one of claims 1 to 8, this installation essentially comprising a station (1) for grinding and defibrating lignocellulosic raw materials (2), a station (3) for progressively drying the wood fibers (4) from station (1), a station (5) for sizing the dried fibers (4), for example of the mixer, sizing tower or similar type, a station (6) for conveying and shaping the sizing fibers (4) into a cake or mat (7), a first station (8) for pressing the cake or mat (7), referred to as the pre-pressing station, a second pressing station (9), final pressing and polymerization of the binder, with application of at least one heat flow through the cake or mat (7), a panel cutting station (10), with possible machining, and a resulting panel conditioning station (12), these stations (1, 3, 5, 8, 9, 10, 12) being arranged in series to form a production line.