Aqueous adhesive composition comprising a thermosetting resin for bonding fibre materials

Abstract

The invention relates to an aqueous adhesive composition obtained by mixing: - 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; and - 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 a basic solvent, the aqueous adhesive composition preferably having a pH strictly greater than 10.0 or a pH ranging from 6.0 to 7.5.

Description

AQUEOUS ADHESIVE COMPOSITION CONTAINING A RESIN THERMOSETTING COMPOUND DESIGNED FOR BINDING FIBER MATERIALS

[0001] The field of the present invention relates to aqueous adhesive compositions intended for bonding fibrous materials, their use for example in manufacturing insulating elements and glued assemblies of fibrous materials.

[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[0003] Phenoplasts have gradually been replaced by other technologies such as polyurethanes, which have the particularity of not releasing volatile organic compounds (VOCs) once cross-linked, thus allowing the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 an aqueous adhesive composition that achieves technical performance similar to traditional binders while having good water resistance with a binder that has good shelf-life stability, and without using substances that meet SVHC criteria (substances of very high concern).

[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, a first object of the invention relates to an aqueous adhesive composition obtained by mixing: - of at least one aromatic compound A1 comprising at least one aromatic ring bearing at least two functional groups, one of these functional groups being an aldehyde or a hydroxymethyl functional group, the other being an aldehyde or a hydroxymethyl functional group, and - 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 a basic solvent, having a pH strictly greater than 10.0.

[0009] A second object of the invention relates to an adhesive composition obtained by mixing: - of at least one aromatic compound A1 comprising at least one aromatic ring bearing at least two functional groups, one of these functional groups being an aldehyde or a hydroxymethyl functional group, the other being an aldehyde or a hydroxymethyl functional group, and - 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 a basic solvent, having a pH ranging from 6.0 to 7.5.

[0010] In the two aqueous adhesive compositions according to a first and a second embodiment of the invention, it is understood that the pH is that of the final aqueous adhesive composition obtained by mixing the aromatic compound A1, the aromatic phenol compound A2 and the basic solvent.

[0011] Another object of the invention relates to the use of the first or second composition as described above 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.

[0012] Yet another object of the invention relates to a bonded assembly of at least two fibrous materials with a density less than or equal to 450 kg / m³ 3 comprising a layer of the first or second composition as described above joining at least one of the materials to the other.

[0013] The invention and its advantages will be readily understood in light of the following description. I-FORMULATION OF THE AQUEOUS ADHESIVE COMPOSITION

[0001] In this description, unless expressly stated otherwise, all percentages (%) indicated are % by mass.

[0002] By "para position relative to each other," it is understood that the functions 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 function is a position opposite to that function on the 6-membered aromatic ring bearing the function.

[0003] By "in the ortho position of a function," we mean the position occupied by the carbon of the aromatic ring immediately adjacent to the carbon of the aromatic ring bearing the function. Similarly, "the ortho position" with respect to a function is the position adjacent to the function on the aromatic ring bearing the function.

[0004] By "meta position of a function," we mean the position occupied by the carbon of the aromatic ring separated from the carbon of the aromatic ring bearing the function by a single other carbon of the aromatic ring. Similarly, the "meta position" with respect to a function is the position adjacent to the "ortho function" on the aromatic ring bearing the function.

[0005] By "meta position relative to each other", it will be understood 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.

[0006] By "link" of a nucleus, we mean an atom constituting the nucleus's skeleton. Thus, for example, a benzene ring comprises six links, each link consisting of a carbon atom. In another example, a furanine ring comprises five links, four of which are each consisting of a carbon atom and the remaining link consisting of an oxygen atom.

[0007] “CHO” represents the aldehyde function.

[0008] “CH2OH” represents the hydroxymethyl function.

[0009] “Compound A1” refers, within the framework of the invention, to the aromatic compound defined in paragraph 11.1.

[0010] "Compound A2" refers, within the framework of the invention, to the aromatic polyphenol-based compound defined in paragraph II.2.

[0011] 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.

[0012] Within the scope of the invention, it may also be envisaged that the carbon products mentioned in the description include isotopes of certain chemical elements.

[0013] 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 to say, 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 to say, including the strict bounds a and b).

[0014] 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.

[0015] 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

[0016] 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.

[0017] 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.

[0018] 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.

[0019] The aromatic ring can bear 0, 1 or 2 aldehyde functions, advantageously 0 or 1 aldehyde function.

[0020] The aromatic ring can bear 1, 2 or 3 hydroxymethyl functions, advantageously 1 or 2 hydroxymethyl functions.

[0021] In addition, the aromatic ring can also carry 0, 1 or 2 other function(s), in particular hydroxyl.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] Advantageously, apart from the aldehyde and hydroxymethyl functions, the rest of the aromatic ring is not substituted.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] In a first variant, compound A1 has the general formula (II'): in which X, B are as defined previously.

[0031] In a particularly advantageous embodiment, B represents CHO. In another embodiment, B represents CH2OH.

[0032] According to a preferred embodiment, X represents O.

[0033] In this embodiment, compound A1 has the formula (lia): B being as defined previously and more particularly of formula (H'a1) or (H'a2): (irai) (liTa2)

[0034] 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.

[0035] 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):

[0036] In another embodiment, X represents NR1 or NO, advantageously NR1. Ri is as defined previously.

[0037] In one variant, compound A1 has the formula (lib): B being as defined previously and more particularly of formula (H'b1) or (H'b2): 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.

[0038] In another embodiment, X represents S, SO, SO2 or SR2R3.

[0039] In this embodiment, compound A1 has the formula (link): B being as defined previously 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.

[0040] Compound A1 can therefore be:

[0041] Advantageously R2, R3 each represent, independently of each other, an alkyl radical in Ci-Ce.

[0042] Compound A1 is advantageously of formula (H'c1) or (I I'c2).

[0043] 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.

[0044] The B and hydroxymethyl functions are advantageously in meta or para positions relative to each other.

[0045] The aromatic ring can bear 0, 1 or 2 aldehyde functions, advantageously 0 or 1 aldehyde function.

[0046] The aromatic ring can bear 1, 2 or 3 hydroxymethyl functions, advantageously 1 or 2 hydroxymethyl functions.

[0047] 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.

[0048] Advantageously m is equal to 0 or 1.

[0049] Advantageously D represents a hydrogen or hydroxymethyl group.

[0050] In one variant, n equals 1 and p equals 1.

[0051] In another variant, n equals 3 and p equals 0.

[0052] In another variant, n equals 2 and p equals 1.

[0053] In another variant, n equals 1 and p equals 2.

[0054] In another variant, n equals 0 and p equals 2.

[0055] In another variant, n equals 0 and p equals 3.

[0056] 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.

[0057] 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):

[0058] Preferably, when the thermosetting resin is based on polyphenol and one or more compounds of formula (I), the composition is free of formaldehyde.

[0059] 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.

[0060] In other words, and preferably, when an aldehyde is present, the aldehyde or each aldehyde in the thermosetting resin is different from formaldehyde.

[0061] 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. I.2 - Aromatic phenol compound A2

[0062] 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.

[0063] 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.

[0064] Preferably, the two ortho positions of each hydroxyl function of at least one aromatic ring are unsubstituted.

[0065] Even more preferentially, the two ortho positions of each hydroxyl function of each aromatic ring are unsubstituted.

[0066] 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.

[0067] 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.

[0068] Advantageously, each aromatic ring of the aromatic polyphenol is a benzene ring.

[0069] 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):

[0070] 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.

[0071] Another example of an aromatic polyphenol is 2,2',4,4'-tetrahydroxydiphenyl sulfide with the following structural formula (VII):

[0072] Another example of an aromatic polyphenol is 2,2',4,4'-tetrahydroxydiphenyl benzophenone with the following structural formula (VIII):

[0073] 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.

[0074] 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.

[0075] 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.

[0076] In a particularly advantageous embodiment, the aromatic polyphenol is phloroglucinol. 1.3 - Additives - Preparation of the aqueous adhesive composition

[0077] 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 that modify the setting or gelling time and the open time of the resin.As is well known to those skilled in the art, setting or gel time is the time during which the resin can be applied to its substrate, and open time is the time during which, after application, the resin can be left exposed to air without compromising the quality of the subsequent adhesive bond with the additional substrate. Setting or gel time and open time are dependent on factors such as temperature, pressure, and resin concentration.

[0078] In the first embodiment of the invention, the quantity of basic solvent ranges from 6 to 10% by weight and preferably from 7 to 9% of the final solution.

[0079] In the second embodiment of the invention, the quantity of basic solvent ranges from 1 to 3% by weight of the final solution.

[0080] Advantageously, in both embodiments of the invention the basic solvent is sodium hydroxide.

[0081] 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.

[0082] 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.

[0083] 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 a person skilled in the art will be able to adjust the quantities of these additives according to their own constraints and industrial requirements.

[0084] 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 use time of the composition, the expert will determine the possible storage time based on the concentration of the composition.

[0085] Preferably, the water content of the aqueous adhesive composition ranges from 10 to 95% by weight, preferably from 20 to 80% by weight.

[0086] The total dry extract content of the adhesive composition is defined as the ratio of the mass of residue obtained after drying of the adhesive composition to the mass of the adhesive composition before drying.

[0087] 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.

[0088] These two dry extract rates are measured in accordance with the NF EN 827 standard (March 2006).

[0089] Water content of the aqueous adhesive composition means the weight of water relative to the total weight of the adhesive composition. II-FIBER MATERIALS

[0090] The fibrous materials according to the invention are low-density materials. Low densities are defined as densities up to 450 kg / m³ 3, and preferably ranging from 200 to 300 kg / m 3 .

[0091] Advantageously, the materials are chosen from natural organic or mineral fibers and synthetic fibers.

[0092] It is understood that when we talk about fibers, we include natural fibers, whether organic or mineral.

[0093] Advantageously, natural organic fibers are chosen from among fibers of animal origin and fibers of plant origin, and in particular wood fibers.

[0094] 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).

[0095] 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).

[0096] The term "organic fibers" also includes synthetic fibers. These can be derived from industrial waste and recycling. Some examples include acrylic, polypropylene, and polyester.

[0097] Preferably, natural mineral fibers are chosen from fiberglass, carbon fiber, rock wool, quartz wool and asbestos.

[0098] 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.

[0099] 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.

[0100] Advantageously, the amount of resin ranges from 3.5% to 7.0% and preferably from 4.0% to 6.0%. III-MANUFACTURING OF THE ASSEMBLY AND METHOD FOR BONDING FIBER MATERIALS

[0101] According to the invention, the assembly is bonded with at least two fibrous materials with a density less than or equal to 450 kg / m³. 3 , comprising a layer of the aqueous adhesive composition as previously described by joining at least one of the materials to the other.

[0102] For example, an assembly 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.

[0103] For example, cooking can be done by heating press or by microwave.

[0104] In one embodiment, the fibrous materials are made of wood fiber.

[0105] 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

[0106] These tests demonstrate that the compression and tensile performance of the resin-based insulation elements according to the invention as described above is equivalent to that of polyurethane resin-based elements, as well as water resistance and stability over time.

[0107] To this end, six aqueous adhesive compositions were prepared, four according to the embodiment of the invention (hereafter referred to as C-4 to C-6), one not according to the invention (control composition referred to hereafter as C-1) and two compositions Controls C-2 and C-3. 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).

[0108] The adhesive composition C-1 is a control composition based on 4,4'-methylenediphenyl diisocyanate (MDI).

[0109] The control adhesive compositions C-2 and C-3 are aqueous control adhesive compositions based on 5-(hydroxymethyl)-furfural and phloroglucinol at a pH of 9.

[0110] Adhesive compositions C-4 and C-5 are aqueous adhesive compositions according to the first embodiment of the invention based on 5-(hydroxymethyl)-furfural and phloroglucinol at a pH of 12.

[0111] The C-6 adhesive composition is an aqueous adhesive composition according to the second embodiment of the invention based on 5-(hydroxymethyl)-furfural and phloroglucinol at a pH of 7.5.

[0112] Protocol for preparing the aqueous adhesive composition

[0113] 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.

[0114] At the end of this time, the aqueous adhesive composition according to the embodiment of the invention is ready to be used.

[0115] The product is then stored in a 250 mL screw-cap bottle at room temperature. Viscosity is measured at each point. A Brookfield viscometer with a standard spindle adapted to the viscosity range is used. After the product has been brought to 20 °C, the viscosity is measured three times, and an average measurement is taken. Viscosity is measured until it exceeds 1000 cP. This value was determined empirically, based on the ease of spraying the resin at 20 °C. A result marked (+++) indicates that the composition is very stable over time, a result marked (++) indicates that the composition has good stability over time, and a result marked (--) or (-) indicates that the composition should be used quickly. Test tube preparation protocol

[0116] 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.

[0117] 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.

[0118] 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.

[0119] Compression and tensile test of the element

[0120] The evaluation results of the elements are obtained by subjecting them to compression.

[0121] Mechanical test execution protocol

[0122] 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%.

[0123] Furthermore, in this same standard, tensile strength is determined.

[0124] 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.

[0125] Water resistance tests:

[0126] According to ACERMI certification -> as described by standard NF EN 1609, tests by partial immersion for 24 hours. Determination of short-term water absorption: WS classification - short-term water absorption < 1 kg / m³ 2 .

[0127] A very good water resistance result is noted (++) and an average water resistance result is noted (--).

[0128] The results of the tests carried out on the test tubes are summarized in Table 1 below.

[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] It is observed that the adhesive compositions C-4 and C-5 according to the first embodiment of the invention have much better stability over time compared to the control compositions C-2 and C-3 and equivalent stability to the control C-1, without significantly degrading water resistance compared to the control compositions C-2 and C-3.

[0131] It is observed that the adhesive composition C-6 according to the second embodiment of the invention, in addition to having much better stability over time compared to the control compositions C-2 and C-3, has a significantly improved water resistance compared to the control compositions C-2 and C-3 and is equivalent to the control composition C-1.

[0132] It is observed that, like the element made with composition C-1, the elements made with adhesive compositions C-4 to C-6 according to the first and second embodiment of the invention exhibit an adhesive performance, represented by the tensile test, equivalent or even superior to that of element C-1.

[0133] Regarding compression characteristics, the elements made with adhesive compositions C-4 to C-6 according to the embodiment of the invention also exhibit performance equivalent to composition C-1.

[0134] Thus, the composite according to the invention makes it possible to obtain technical performances similar to traditional binders while having good water resistance and the binder good preservation stability, and this without using substances meeting the SVHC criteria (substances of very high concern).

[0135] The invention is not limited to the embodiments described above.

[0136] In another embodiment, the aqueous adhesive composition further comprises a monosaccharide selected from the group consisting of fructose, glucose, xylose, erythrose and mixtures of these compounds.

[0137] In yet another embodiment, the aqueous adhesive composition further comprises an oligosaccharide selected from the group consisting of sucrose, glucose and fructose oligomers and mixtures of these compounds.

[0138] In these embodiments, the stability of the composition is increased.

Claims

DEMANDS 1. Aqueous adhesive composition obtained by mixing: - of at least one aromatic compound A1 comprising at least one aromatic ring bearing at least two functional groups, one of these functional groups being an aldehyde or a hydroxymethyl functional group, the other being an aldehyde or a hydroxymethyl functional group, and - 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 a basic solvent; wherein the quantity of basic solvent ranges from 6 to 10% by weight of the final solution and the aqueous adhesive composition has a pH strictly greater than 10.

0.

2. Aqueous adhesive composition obtained by mixing: - of at least one aromatic compound A1 comprising at least one aromatic ring bearing at least two functional groups, one of these functional groups being an aldehyde or a hydroxymethyl functional group, the other being an aldehyde or a hydroxymethyl functional group, and - 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 a basic solvent; wherein the quantity of basic solvent ranges from 1 to 3% by weight of the final solution and the aqueous adhesive composition has a pH ranging from 6.0 to 7.

5.

3. Aqueous adhesive composition according to claim 1, wherein the amount of basic solvent is from 7 to 9% of the final solution.

4. Aqueous adhesive composition according to any one of the preceding claims, wherein the basic solvent is sodium hydroxide.

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

6. Composition according to any one of the preceding claims, wherein compound A2 comprises an aromatic ring of the aromatic polyphenol which is carrier of three hydroxyl functions in meta positions relative to each other.

7. Composition according to any one of claims 1 to 6, 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.

8. Use of the composition according to any one of claims 1 to 7 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.

9. Bonded assembly of at least two fibrous materials with a density less than or equal to 450 kg / m³ 3 comprising a layer of the aqueous adhesive composition according to any one of claims 1 to 7 joining at least one of the materials to the other.

10. Glued assembly according to the preceding claim, wherein the materials are selected from natural organic or mineral fibers and synthetic fibers.

11. Glued assembly according to claim 10, wherein the organic natural fibers are selected from fibers of animal origin and fibers of vegetable origin and in particular wood fibers.

12. Bonded assembly according to claim 10, wherein the natural mineral fibers are selected from glass fiber, carbon fiber, rock wool, quartz wool and asbestos.

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