Composite comprising fibre materials bonded by an aqueous adhesive composition comprising a thermosetting resin

Abstract

The invention concerns a composite comprising fibre materials with a density of less than or equal to 450 kg / m3 bonded by an aqueous adhesive composition. The composition comprises a thermosetting resin based on: - at least one aromatic compound A1 comprising at least one aromatic ring bearing at least two functions, one of these functions being an aldehyde function or a hydroxymethyl function and the other being an aldehyde function or a hydroxymethyl function; - at least one aromatic phenol compound A2 bearing at least one aromatic ring bearing at least two hydroxyl functions, said functions being in the meta position relative to one another, the two positions ortho to at least one of the hydroxyl functions being unsubstituted; in which the amount of resin is at least 3.5% by weight of dry extract of resin relative to the total weight of the composition.

Description

COMPOSITE COMPRISING FIBERS BOUND BY A COMPOSITION AQUEOUS ADHESIVE CONTAINING A THERMO-SETTING RESIN

[0001] The field of the present invention relates to composites based on fibrous materials and aqueous adhesive compositions intended to bind these fibrous materials, the process of manufacturing such composites and their use for example to manufacture low density elements that can be used as insulation and / or for hydroponic crops.

[0002] Phenoleplasts, or phenol-formaldehyde resins (PF), are derived from formaldehyde and phenol. Because phenol is a molecule with multiple reactive sites, a three-dimensional network is formed. Phenoleplasts are notably used as adhesives, for example, in the manufacture of insulation materials. However, the use of formaldehyde (or formalin), especially in excess of phenol, leads to the release of formaldehyde not only during pressure curing but also during the storage and use of the composite. Due to recent regulatory changes, particularly European regulations on this type of compound, the aim is to limit, or even eliminate, the use of formaldehyde or formaldehyde precursors as much as possible.

[0003] Phenoplasts have gradually been replaced by other technologies such as polyurethanes, which have the particularity of not releasing volatile organic compounds (VOCs) once cross-linked, thus allowing the final insulating material to obtain an excellent classification on its level of emission of volatile substances into the indoor air.

[0004] In the field of insulation, polyurethanes are described in applications WO2013113912 and US2015330070.

[0005] However, the toxicity problem remains unresolved, as the polyurethane family uses isocyanates, and very often 4,4'-methylenediphenyl diisocyanate (MDI), as a starting material. Exposure to MDI is a major cause of occupational asthma, in addition to causing irritation and allergies.

[0006] The invention aims to provide a composite comprising an aqueous adhesive composition enabling technical performance similar to traditional binders, without using substances meeting SVHC (substances of very high concern) criteria.

[0007] However, during its research, the Applicant discovered an aqueous adhesive composition that does not use free formaldehyde or polyurethanes, which makes it possible to meet the above objective.

[0008] Thus, the object of the invention relates to a composite comprising fibrous materials with a density less than or equal to 450 kg / m³ 3 bonded by an aqueous adhesive composition comprising a thermosetting resin based on: - of at least one aromatic compound A1 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; - of 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; in which the quantity of resin is at least 3.5% by weight of dry resin extract relative to the total weight of the composition.

[0009] Another object of the invention is the use of the composite for the manufacture of elements with a density less than or equal to 450 kg / m³ 3 which can be used as insulation and / or for hydroponic cultivation.

[0010] The invention and its advantages will be readily understood in light of the following description. FIBER MATERIALS

[0011] The fibrous materials according to the invention are low-density materials. Low density is defined as densities up to 450 kg / m³. 3, and preferably ranging from 200 to 300 kg / m 3 .

[0012] Advantageously, the materials are chosen from natural organic or mineral fibers and synthetic fibers.

[0013] It is understood that when we talk about fibers, we include natural fibers, whether organic or mineral.

[0014] Advantageously, natural organic fibers are chosen from among fibers of animal origin and fibers of plant origin, and in particular wood fibers.

[0015] Among organic fibers, we find, for example, fibers of animal origin. They exhibit a very high elongation at break. They come from hair, wool (animal fur) or even secretions (silk).

[0016] Among the commonly used plant or cellulosic fibers are fibers derived from: - seminal hairs from seeds (cotton), - plant stems (flax, hemp, jute, grass), - of leaves (sisal), - of trunks (palm tree), or - fruit husks (coconut).

[0017] The term "organic fibers" also includes synthetic fibers. These can be derived from industrial waste and recycling. Some examples include acrylic, polypropylene, and polyester.

[0018] Preferably, natural mineral fibers are chosen from fiberglass, carbon fiber, rock wool, quartz wool and asbestos.

[0019] Among the mineral fibers, we find for example, and in a non-exhaustive way: glass fiber or wool, carbon fiber, rock wool (basalt), quartz wool or even asbestos.

[0020] The terms "wool" and "fiber" are sometimes used to refer to the same raw material, as in the case of wool or wood or glass fiber.

[0021] Advantageously, the amount of resin ranges from 3.5% to 7.0% and preferably from 4.0% to 6.0%. II- FORMULATION OF THE AQUEOUS ADHESIVE COMPOSITION

[0022] In this description, unless expressly stated otherwise, all percentages (%) shown are % by mass.

[0023] By "para position relative to each other," we mean that the functional groups in question are opposite each other, that is, in positions 1 and 4 of the 6-membered aromatic ring. Similarly, the "para position" relative to a functional group is a position opposite that functional group on the 6-membered aromatic ring bearing the functional group.

[0024] By "ortho position of a functional group," we mean the position occupied by the carbon atom of the aromatic ring immediately adjacent to the carbon atom of the aromatic ring bearing the functional group. Similarly, the "ortho position" with respect to a functional group is the position adjacent to the functional group on the aromatic ring bearing the functional group.

[0025] By "meta position of a functional group," we mean the position occupied by the carbon atom of the aromatic ring separated from the carbon atom of the aromatic ring bearing the functional group by a single other carbon atom of the aromatic ring. Similarly, the "meta position" with respect to a functional group is the position adjacent to the "ortho functional group" on the aromatic ring bearing the functional group.

[0026] By "meta position relative to each other", we mean that the functions in question, for example the hydroxyl functions in the aromatic polyphenol, are carried by carbons of the aromatic ring separated from each other by a single other carbon of the aromatic ring.

[0027] By "link" of a nucleus, we mean an atom that makes up the nucleus's skeleton. For example, a benzene ring has six links, each link consisting of a carbon atom. In another example, a furan ring comprises five links, four links being each made up of a carbon atom and the remaining link being made up of an oxygen atom.

[0028] “CHO” represents the aldehyde function.

[0029] “CH2OH” represents the hydroxymethyl function.

[0030] "Compound A1" refers, within the context of the invention, to the aromatic compound defined in paragraph 11.1.

[0031] "Compound A2" refers, within the context of the invention, to the aromatic polyphenol-based compound defined in paragraph II.2.

[0032] Within the scope of the invention, the carbon products mentioned in the description may be of fossil origin or bio-based. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass.

[0033] Within the framework of the invention, it may also be envisaged that the carbon products mentioned in the description include isotopes of certain chemical elements.

[0034] On the other hand, any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​going from more than a to less than b (that is, bounds a and b excluded) while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​going from a to b (that is, including the strict bounds a and b).

[0035] The expression "composition based on" should of course be understood as a composition comprising the mixture and / or reaction product of the various basic constituents used for this composition, some of which may be intended to react or likely to react with each other or with their immediate chemical environment, at least in part, during the various manufacturing phases of the composition, textile material, composites or finished articles comprising such composites, in particular during a cooking stage.

[0036] The aqueous adhesive composition according to a first embodiment of the invention therefore comprises at least one (i.e., one or more) thermosetting resin according to the invention; this thermosetting resin is itself based on at least one (i.e., one or more) aromatic compound and at least one (i.e., one or more) aromatic polyphenol, constituents which will be described in detail below. 1 - Aromatic compound A1

[0037] The first essential constituent of the thermosetting resin is an aromatic compound A1 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.

[0038] Thus, according to the invention, it is said aromatic ring that bears the hydroxymethyl functions or the hydroxymethyl and aldehyde functions. The compound according to the invention therefore corresponds to the general formula (I): B-Ar-C (I) where Ar represents an aromatic ring and B, C represent CHO or CH2OH respectively.

[0039] 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 a variant, the aromatic ring comprises 0, 1, or 2 heteroatoms. The remainder of the aromatic ring may or may not be substituted.

[0040] The aromatic ring can bear 0, 1 or 2 aldehyde functions, advantageously 0 or 1 aldehyde function.

[0041] The aromatic ring can bear 1, 2 or 3 hydroxymethyl functions, advantageously 1 or 2 hydroxymethyl functions.

[0042] In addition, the aromatic ring can also carry 0, 1 or 2 other function(s), in particular hydroxyl.

[0043] 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.

[0044] 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, and sulfur atoms, optionally oxidized as N-oxide or S-oxide. Advantageously, the aromatic ring comprises one or two heteroatoms, preferably one heteroatom.

[0045] 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 nucleus 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.

[0046] Advantageously, apart from the aldehyde and hydroxymethyl functions, the rest of the aromatic ring is not substituted.

[0047] Advantageously, in the first case, the aromatic core comprises: - a single aldehyde function; - a single hydroxymethyl function; - apart from the aldehyde and hydroxymethyl functions, the rest of the aromatic ring is not substituted.

[0048] Advantageously, in a second case, the aromatic core comprises: - two hydroxymethyl functions; - apart from the hydroxymethyl functions, the rest of the aromatic ring is not substituted.

[0049] Advantageously, in a third case, the aromatic core comprises: - two aldehyde functions; - apart from the aldehyde functions, the rest of the aromatic ring is not substituted.

[0050] Advantageously, the aromatic compound A1 corresponds to the general formula (H): in which B and C represent CHO or CH2OH respectively, X represents O, NR1, NO, S, SO, SO2, SR2R3, Ri, R2, R3 each represent, independently of each other, a hydrogen, an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group.

[0051] In a first variant, compound A1 has the general formula (II'): in which X, B are as defined previously.

[0052] In a particularly advantageous embodiment, B represents CHO. In another embodiment, B represents CH2OH.

[0053] According to a preferred embodiment, X represents O.

[0054] In this embodiment, compound A1 has the formula (Ha): B being as defined previously and more particularly of formula (H'a1) or (H'a2): (I will go) (he has 2)

[0055] Preferably, 5-(hydroxymethyl)furfural (H'a1) is a particularly suitable aldehyde, given that this organic compound can easily be obtained from renewable resources. Indeed, it is derived, in particular, from the dehydration of certain sugars such as fructose, glucose, sucrose, cellulose, and inulin.

[0056] In a second variant, compound A1 has the general formula (II”): B being as defined previously and more particularly of formula (Il”a1) or (H”a2):

[0057] In another embodiment, X represents NRi or NO, advantageously NRi. Ri is as defined previously.

[0058] In one variant, compound A1 has the formula (llb): B being as defined previously and more particularly of formula (H'b1) or (H'b2): (H'b1) (Il'b2i in which Ri represents a hydrogen, an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group. Advantageously Ri represents a hydrogen or an alkyl group in Ci-Ce.

[0059] In another embodiment, X represents S, SO, SO2 or SR2R3.

[0060] In this embodiment, compound A1 has the formula (Ile): B being such as defined previously die) with X representing S, SR2R3, SO, SO2, R2, R3 each represent, independently of each other, a hydrogen, an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group, B being as defined previously; and more particularly of formula (H'c1) or (H'c2): in which X represents S, SR2R3, SO, SO2, R2, R3 each represent, independently of each other, a hydrogen, an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group.

[0061] Compound A1 can therefore be:

[0062] Advantageously R2, R3 each represent, independently of each other, an alkyl radical in Ci-Ce.

[0063] Compound A1 is advantageously of formula (H'c1) or (I I'c2).

[0064] In another variant, the aromatic ring is a 6-membered ring, which may include 0, one, or more heteroatoms, particularly nitrogen, possibly oxidized as an N-oxide. In a further variant, the aromatic ring comprises 0, 1, or 2 heteroatoms.

[0065] The B and hydroxymethyl functions are advantageously in meta or para positions relative to each other.

[0066] The aromatic ring can bear 0, 1 or 2 aldehyde functions, advantageously 0 or 1 aldehyde function.

[0067] The aromatic ring can bear 1, 2 or 3 hydroxymethyl functions, advantageously 1 or 2 hydroxymethyl functions.

[0068] Advantageously, compound A1 has the general formula (III): (III) in which D represents a hydrogen, an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl, or a hydroxyalkyl group. According to the invention, p+n>1 and m<5.

[0069] Advantageously m is equal to 0 or 1.

[0070] Advantageously D represents a hydrogen or hydroxymethyl group.

[0071] In one variant, n equals 1 and p equals 1.

[0072] In another variant, n equals 3 and p equals 0.

[0073] In another variant, n equals 2 and p equals 1.

[0074] In another variant, n equals 1 and p equals 2.

[0075] In another variant, n equals 0 and p equals 2.

[0076] In another variant, n equals 0 and p equals 3.

[0077] Preferably, the aromatic ring of aromatic compound A1 is a benzene ring. More preferably, this aldehyde is chosen from the group consisting of 2-hydroxymethylbenzene-1-carboxaldehyde, 3-hydroxymethylbenzene-1-carboxaldehyde, 4-hydroxymethylbenzene-1-carboxaldehyde, 1,2-hydroxymethylbenzene, 1,3-hydroxymethylbenzene, 1,4-hydroxymethylbenzene, 2-Methoxybenzaldehyde, 3-Methoxybenzaldehyde, 4-Methoxybenzaldehyde, 2,6-Dimethoxybenzaldehyde, 2,4,6-Trimethoxybenzaldehyde, and mixtures of these compounds.

[0078] Even more preferentially, the aromatic compound A1 used is 1-hydroxymethyl-benzene-4-carboxaldehyde with the formula (Ilia) or 1,4-hydroxymethyl-benzene with the formula (lllb) or terephthalic acid with the formula (IH'b):

[0079] Preferably, when the thermosetting resin is based on polyphenol and one or more compounds of formula (I), the composition is free of formaldehyde.

[0080] When the thermosetting resin is based on polyphenol, one or more compounds of formula (I) and aldehydes, each aldehyde is preferentially different from formaldehyde. The composition is then also formaldehyde-free.

[0081] In other words, and preferably, when an aldehyde is present, the aldehyde or each aldehyde in the thermosetting resin is different from formaldehyde.

[0082] By formaldehyde-free, we mean that the mass percentage of formaldehyde in total weight of the aldehyde(s) is less than or equal to 10%, preferably 5% and more preferably 2%, these percentages corresponding to traces likely to be present in the aldehyde(s) used industrially. II.2 - Aromatic phenol compound A2

[0083] The second essential constituent of the thermosetting resin is 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.

[0084] In a preferred embodiment, at least one of the aromatic rings of the aromatic polyphenol bears three hydroxyl functions in meta positions relative to each other.

[0085] Preferably, the two ortho positions of each hydroxyl function of at least one aromatic ring are unsubstituted.

[0086] Even more preferentially, the two ortho positions of each hydroxyl function of each aromatic ring are unsubstituted.

[0087] Even more preferably, the remainder of each aromatic ring 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.

[0088] Advantageously, the aromatic ring bearing at least two hydroxyl functions in meta positions relative to each other, with the two ortho positions of at least one of the hydroxyl functions being unsubstituted, is a benzene ring.

[0089] Advantageously, each aromatic ring of the aromatic polyphenol is a benzene ring.

[0090] As an example of an aromatic polyphenol containing a single aromatic ring, we can cite in particular resorcinol and phloroglucinol, for a reminder of their respective structural formulas (IV) and (V):

[0091] For example, in cases where the aromatic polyphenol has several aromatic rings, at least two of these aromatic rings, identical or different, are chosen from those with general formulas: in which the symbols Zi, Z2, identical or different if there are several on the same aromatic nucleus, represent an atom (for example carbon, sulfur or oxygen) or a bonding group by definition at least divalent, which links at least these two aromatic nuclei to the rest of the aromatic polyphenol.

[0092] Another example of an aromatic polyphenol is 2,2',4,4'-tetrahydroxydiphenyl sulfide with the following structural formula (VII):

[0093] Another example of an aromatic polyphenol is 2,2',4,4'-tetrahydroxydiphenyl benzophenone with the following structural formula (VIII):

[0094] It is noted that each compound VII and VIII is an aromatic polyphenol comprising two aromatic rings (of formula Vl-c) each of which carries at least two (in this case two) hydroxyl functions in meta position relative to each other.

[0095] Note that in the case of an aromatic polyphenol with at least one aromatic ring conforming to the formula Vl-b, the two ortho positions of each hydroxyl group of at least one aromatic ring are unsubstituted. In the case of an aromatic polyphenol with several aromatic rings conforming to the formula Vl-b, the two ortho positions of each hydroxyl group of each aromatic ring are unsubstituted.

[0096] According to one 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.

[0097] In a particularly advantageous embodiment, the aromatic polyphenol is phloroglucinol. II.3 Compound (C)

[0098] Advantageously, the aqueous adhesive composition further comprises a compound of formula (C): in which each group R1, R2, R3 independently represents an alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl, or hydrogen group, X represents S, O, or N-R4 with R4 representing an alkyl, aryl, arylalkyl, alkylaryl, or cycloalkyl group

[0099] Preferably, R1 and / or R2 and / or R3 represent hydrogen. Preferably, X represents O.

[0100] Advantageously, compound (C) is urea with the formula: O H2N / NH2

[0101] As previously mentioned, the mass concentration of urea is preferably between 0.3% and 20% relative to the mass concentration of dry extract in the adhesive composition. Within this range, cold stability is optimal, and the shelf life of the aqueous adhesive composition allows for greater flexibility in use.

[0102] A rate above 20% would greatly improve cold stability but adhesive performance would be severely degraded.

[0103] A rate lower than 0.3% would not be sufficient to shift the properties of the composition. II.4 Additives - Preparation of the aqueous adhesive composition

[0104] The aqueous adhesive composition according to the embodiment of the invention may, of course, include all or some of the usual additives for aqueous adhesive compositions such as those used in conventional phenolic adhesives; examples include bases such as ammonia, sodium, potassium, or ammonium hydroxide, colorants, fillers such as carbon black, silica, chalk, olive pomace, or any other natural fillers, antioxidants or other stabilizers, thickeners, for example, carboxymethylcellulose, or gelling agents, for example, gelatin, to increase the viscosity of the composition. Also included are additives for modifying the setting or gelling time and the open time of the resin. As is known to those skilled in the art, the setting time The setting or gel time is the time during which the resin can be applied to its substrate, and the open time is the time during which, after application, the resin can be left exposed to air without affecting the quality of the subsequent adhesive bond with the additional substrate. The setting or gel time and the open time depend on factors such as temperature, pressure, and resin concentration.

[0105] Typically, when preparing the resin, the constituents of the thermosetting resin itself are mixed without a predefined order, but advantageously by first mixing the water with the soda, then the aromatic phenol compound A2, and then the aromatic compound A1.

[0106] Advantageously, in one embodiment, the aqueous adhesive composition is obtained by mixing: - of aromatic compound A1; and - of aromatic compound A2; in a basic solvent preferably having a pH between 8 and 10, more preferably between 8.5 and 9.5.

[0107] Thermosetting resin can be produced at a pH between 8 and 10, more preferably between 8.5 and 9.5.

[0108] The concentration of the composition can be adjusted according to its specific use (opening time, viscosity).

[0109] In another advantageous embodiment, the aqueous adhesive composition is obtained by mixing: in a first phase, a thermosetting resin by mixing: - of aromatic compound A1, and - aromatic polyphenol A2; in a basic solvent preferably having a pH between 8 and 10, more preferably between 8.5 and 9 to obtain a thermosetting resin; and after mixing the resin, a compound (C) is added at a mass rate of dry extract of the aqueous adhesive composition ranging from 0.003 to 0.200 to obtain the aqueous adhesive composition.

[0110] Advantageously, in the final aqueous adhesive composition thus prepared, the dry extract content of thermosetting resin according to the invention ranges from 5 to 90%, more preferably from 10 to 80% by weight of the dry extract of the adhesive composition.

[0111] The characteristics of the adhesive composition described above can be adjusted by adding a number of additives well-known in the literature. These additives include wetting agents, dispersants, thickeners, etc. It is understood that the expert will be able to adjust the quantities of these additives according to his own industrial constraints and needs.

[0112] The composition can be used immediately or stored at room temperature (23°C) or below 23°C but above or equal to 1°C to increase the time of use of the composition, the person skilled in the art will determine the possible storage time according to the concentration of the composition.

[0113] Preferably, the water content of the aqueous adhesive composition ranges from 10 to 95% by weight, preferably from 20 to 80% by weight.

[0114] The total dry extract rate of the adhesive composition is understood to be the ratio of the mass of residue obtained after drying of the adhesive composition to the mass of the adhesive composition before drying.

[0115] The dry extract content of the thermosetting resin is defined as the ratio of the mass of the thermosetting resin obtained after drying of the adhesive composition to the mass of the adhesive composition before drying.

[0116] These two dry extract rates are measured in accordance with the NF EN 827 standard (March 2006).

[0117] Water content of the aqueous adhesive composition means the weight of water relative to the total weight of the adhesive composition. III - Composite Manufacturing and Bonding Process for Fiber Materials

[0118] For example, a composite can be manufactured by bonding fibrous materials with a density less than or equal to 450 kg / m³. 3 , in which: - A layer of the aqueous adhesive composition, as defined above, is applied by spraying onto the fibrous materials, and - the fibrous materials thus pulverized are heated.

[0119] For example, cooking can be done by heating press or by microwave.

[0120] In one embodiment, the fibrous materials are made of wood fiber.

[0121] Preferably, the density of the wood fibre materials is less than or equal to 300 kg / m³ 3 , and more preferably less than or equal to 200 kg / m 3 . IV - EXAMPLES OF INVENTION IMPLEMENTATION AND COMPARATIVE TESTS

[0122] These tests demonstrate that the compression and tension performance of the resin-based insulation elements according to the invention as described above is equivalent to that of polyurethane resin-based elements.

[0123] To this end, 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 referred to hereafter as C-1). 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).

[0124] The adhesive composition C-1 is a control composition based on 4,4'-methylenediphenyl diisocyanate (MDI).

[0125] 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.

[0126] Protocol for preparing the aqueous adhesive composition

[0127] Water and sodium hydroxide are introduced into a 250 mL round-bottom 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.

[0128] At the end of this time, the aqueous adhesive composition according to the embodiment of the invention is ready to be used.

[0129] [Table 1] 1) HMF (from the Aldrich company; purity > 99%); 2) Phloroglucinol (from the company Alfa Aesar; 99% purity); 3) Sodium hydroxide (from the Aldrich company; diluted to 30%).

[0130] Resin adhesion test on the element Test tube preparation protocol

[0131] The quality of the bond between 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.

[0132] More specifically, each test specimen is obtained by mixing 350 g of fiber and 16 g of resin for C-1 (reference PU) for 2 minutes, 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, using a mat with a 4 cm gap via a heating press between 80 °C and 160 °C for 60 seconds to 1 hour, or by microwave heating.

[0133] The % of resin is then indicated; the control composition C-1 has a resin content of 4.5% for 95.5% fibers when weighing the test specimen.

[0134] Compression and tensile test of the element

[0135] The evaluation results of the elements are obtained by subjecting them to compression.

[0136] Mechanical test execution protocol

[0137] Wood fiber composites with a density of 120 kg / m³ 3 The specimens are first cut to a dimension 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, in this case 4 cm. The NF EN 826 standard of May 2013 allows the compressive strength value to be determined; this value will be obtained by achieving a relative deformation of 45% and preferably 50%.

[0138] Furthermore, in this same standard, tensile strength is determined.

[0139] 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.

[0140] NA results are not available.

[0141] The results of the tests carried out on the test tubes are summarized in Table 2 below.

[0142] [Table 2]

[0143] It is observed that, like the element made with composition C-1, the elements made with adhesive compositions C-2 and C-3 according to the embodiment of the invention exhibit an adhesive performance, represented by the tensile test, equivalent or even superior to that of element C-1.

[0144] 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 C-1.

[0145] Thus, the composite according to the invention makes it possible to obtain technical performances similar to traditional binders, without using substances meeting the criteria of SVHC (substances of very high concern).

[0146] In conclusion, the results of these various tests clearly demonstrate that the adhesive compositions of the composites according to the invention constitute an interesting alternative to the use of conventional adhesive compositions, by eliminating the extremely concerning molecules.

[0147] The invention is not limited to the embodiments described above.

Claims

DEMANDS 1. Composite comprising fibrous materials with a density less than or equal to 450 kg / m³ 3 bonded by an aqueous adhesive composition characterized in that it comprises a thermosetting resin based on: - of at least one aromatic compound A1 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; - of 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; and in which the quantity of resin is at least 3.5% by weight of dry resin extract relative to the total weight of the composition.

2. Composite according to the preceding claim, wherein the materials are selected from natural organic or mineral fibers and synthetic fibers.

3. Composite according to claim 2, wherein the organic natural fibers are selected from fibers of animal origin and fibers of vegetable origin and in particular wood fibers.

4. Composite according to claim 2, wherein the natural mineral fibers are selected from glass fiber, carbon fiber, rock wool, quartz wool and asbestos.

5. Composite according to any one of the preceding claims, wherein the amount of resin ranges from 3.5% to 7.0% and preferably from 4.0% to 6.0%.

6. Composite according to any one of the preceding claims, wherein compound A1 is 5-(hydroxymethyl)furfural.

7. Composite according to any one of the preceding claims, wherein compound A2 comprises an aromatic polyphenol nucleus bearing three hydroxyl functions in meta positions relative to each other.

8. Composite according to any one of claims 1 to 7, wherein 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.

9. Composite according to any one of the preceding claims, wherein the aqueous adhesive composition is obtained by mixing: - of aromatic compound A1; and - of aromatic compound A2; in a basic solvent preferably having a pH between 8 and 10, more preferably between 8.5 and 9.

5.

10. Composite according to any one of the preceding claims, wherein the aqueous adhesive composition further comprises a compound of formula (C): in which each group R1, R2, R3 independently represents an alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl or hydrogen group, X represents S, O or N-R4 with R4 representing an alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl group; with compound (C) being at a dry extract mass rate of the aqueous adhesive composition ranging from 0.003 to 0.

200.

11. Composite according to the preceding claim, wherein the compound (C) is urea.

12. Composite according to claim 9 or 10 in which the aqueous adhesive composition is obtained by mixing: in a first phase a thermosetting resin by mixing: - of aromatic compound A1, and - aromatic polyphenol A2; in a basic solvent preferably having a pH between 8 and 10, more preferably between 8.5 and 9 to obtain a thermosetting resin; and after mixing the resin, a compound (C) is added at a mass rate of dry extract of the aqueous adhesive composition ranging from 0.003 to 0.200 to obtain the aqueous adhesive composition.

13. Use of the composite according to any one of claims 1 to 12 for the manufacture of an element with a density less than or equal to 450 kg / m³ 3 which can be used as insulation and / or for hydroponic cultivation.

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