Aqueous adhesive composition comprising a thermosetting resin having a low phenol content

Abstract

The present invention relates to an aqueous adhesive composition comprising a thermosetting resin based on: - at least one aromatic hydrocarbon compound A1 comprising at least one aromatic hydrocarbon compound comprising at least two aromatic rings bearing a single hydroxyl function, it being understood that at least one of the ortho or para positions of each aromatic ring is unsubstituted; - at least one aromatic compound A2 comprising a single phenol which is unsubstituted or substituted by a single alkyl or a single alkenyl group; and - a formaldehyde compound A3. According to the invention, the aromatic compound A2 is present in a weight content of the dry extract of the adhesive composition of less than or equal to 0.18.

Description

Technical Field

[0001] The field of the present invention relates to aqueous adhesive compositions intended for adhering elements, uses and methods for preparing such compositions, methods for assembling elements using these compositions, and components produced using these compositions. Background Technology

[0002] Phenolic plastics, or "phenolic resins" (abbreviated PF), are derived from formaldehyde and phenol. Because phenol is a monofunctional monomer capable of undergoing tert-condensation, it ultimately forms a three-dimensional network. Phenolic plastics are particularly used as adhesives, for example, in the preparation of pressed wood materials or composites reinforced with glass fibers, woven fibers, etc.

[0003] In the field of wood, US patent 2360376 describes a phenolic-type composition. This composition comprises a phenolic resin based on formaldehyde and phenol. The phenol content in the solids of the adhesive composition is 26% to 35% by weight. This composition is used in a method of bonding plywood articles comprising multiple boards. In this method, one or more boards are coated with a layer of the composition, the boards are joined together by the composition layer, and the joined boards are cured under pressure. The resulting bonded assembly exhibits high cohesion due to the excellent adhesive properties of the composition.

[0004] In fact, due to recent regulatory changes (particularly European regulations related to these compounds (phenol and formaldehyde), there is a desire to limit (and even eliminate) the use of phenol as much as possible. Alternatives have emerged that use lignin to replace a portion of the phenol molecule. Such an LPF (lignin-phenol-formaldehyde) composition is described in FR3007764. In this composition, lignin is used to replace 50% by weight of the phenol fraction. In the examples of the compositions described in this application, the phenol content in the solids of the adhesive composition is 24% by weight.

[0005] These historical LPF resins are characterized by a high proportion of phenol molecules and the requirement for a specific type of lignin, as described in application FR3007764. A particularly high phenol content is necessary to ensure reproducibility of performance and results. Furthermore, the type of lignin used typically corresponds to a specific type of lignin exemplified in this patent and has a low molecular weight (≤2000 g / mol).

[0006] These precise points make the use of these LPF resin compositions difficult, especially when the application and properties of the resin require lower phenol content, and when the economic balance of the desired application requires a larger, more diverse and cheaper supply of lignin.

[0007] Furthermore, although the substitution of phenol molecules is in the amount of 50% to 60% by weight, the residual proportion associated with formaldehyde (or methanal) contributes to the high toxicity of this type of resin. In fact, due to societal changes (particularly European regulations related to these types of compounds), there is a desire to limit (and even eliminate) the use of aromatic molecules containing a single phenol as much as possible. Summary of the Invention

[0008] In seeking to reduce the phenol molecule content of these types of compositions (LPF), the applicant has discovered a novel composition capable of significantly reducing the content of aromatic molecules containing a single phenol, or even eliminating aromatic molecules containing a single phenol from these compositions.

[0009] The object of the present invention is to provide an aqueous adhesive composition comprising a thermosetting resin, the aqueous adhesive composition exhibiting high adhesive properties and comprising a reduced amount of aromatic molecules comprising a single phenol, or even none of such molecules.

[0010] Therefore, the subject matter of this invention relates to an aqueous adhesive composition comprising a thermosetting resin based on: - At least one aromatic hydrocarbon compound A1, said aromatic hydrocarbon compound A1 comprising at least one aromatic hydrocarbon compound containing at least two aromatic rings, said aromatic rings having a single hydroxyl functional group, and it should be understood that at least one of the ortho or para positions of the hydroxyl functional group of each aromatic ring is unsubstituted. - At least one aromatic compound A2, said aromatic compound A2 comprising a single phenol, said phenol being unsubstituted or substituted with a single alkyl or a single alkenyl group; and - At least one formaldehyde compound A3; Aromatic compound A2 is present in the adhesive composition at a solid weight content of less than or equal to 0.18%.

[0011] The solid weight content of A2 is calculated by dividing the weight of compound A2 by the total solid weight of the adhesive composition.

[0012] Preferably, the solid weight content of aromatic compound A2 in the adhesive composition is 0. Advantageously, in this embodiment, the composition does not contain any aromatic compound A2; it is completely replaced by aromatic hydrocarbon compound A1.

[0013] Advantageously, the degree to which aromatic compound A2 is replaced by aromatic hydrocarbon compound A1 is strictly greater than 60%, preferably in the range of 70% to 100%, and more preferably in the range of 80% to 100%.

[0014] Another subject of the invention relates to the use of the aqueous adhesive composition according to the invention for bonding at least two cellulose-based elements (advantageously at least two elements made of wood).

[0015] The invention also relates to a method for bonding two cellulose-based elements (advantageously two elements made of wood), wherein: - Apply a layer of the aqueous adhesive composition as defined above to at least one element, and - Components are joined together by layers of an aqueous adhesive composition.

[0016] The present invention also relates to an adhesive assembly for two elements, the adhesive assembly comprising a layer of an aqueous adhesive composition as defined above for attaching at least one element to another element. Detailed Implementation

[0017] The invention and its advantages will be readily understood from the following description.

[0018] Formulation of I-waterborne adhesive compositions In this specification, unless otherwise expressly stated, all percentages (%) shown are by weight.

[0019] In the context of this invention, "compound A1" means an aromatic compound as defined in part I.1.

[0020] In the context of this invention, "compound A2" refers to the aromatic polyphenol-based compound defined in part I.2.

[0021] In the context of this invention, "compound A3" refers to the formaldehyde composition defined in part I.3.

[0022] Within the context of this invention, the carbon articles mentioned in the specification may be of fossil origin or bio-based origin. In the case of bio-based carbon articles, they may be partially or wholly derived from biomass, or obtained from renewable starting materials derived from biomass.

[0023] In the context of this invention, it is also conceivable that the carbon-based articles mentioned in the specification contain isotopes of certain chemical elements.

[0024] Furthermore, any numerical interval expressed as "between a and b" represents a range of values ​​greater than a and less than b (i.e., excluding the limits a and b), while any numerical interval expressed as "from a to b" means a range of values ​​from a to b (i.e., including the strict limits a and b).

[0025] The statement “composition based” should naturally be understood to mean that the composition comprises a mixture of various basic components used for the composition and / or reaction products, some of which are intended or capable of reacting at least partially with each other or with their surrounding chemical environment during various stages of production of the composition, wood material, fabric material or composite material or finished product containing such composite material, especially during the curing step.

[0026] Therefore, the aqueous adhesive composition according to the invention comprises at least one thermosetting resin according to the invention, which is itself based on at least one (i.e., one or more) aromatic compounds and at least one (i.e., one or more) aromatic polyphenols, the components of which will be described in detail below.

[0027] I.1-Aromatic compound A1 In embodiments of the present invention, the aromatic hydrocarbon compound A1, described as a poly-monophenol compound, corresponds to the general formula (X): Where Y1 represents alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl, or alkenyl groups, which are substituted, and Y2 and Y3 are the same or different, and represent H or ether groups.

[0028] Advantageously, Y2 and Y3 are located ortho to the hydroxyl functional group and represent H or OY4, wherein Y4 represents alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl or alkenyl, preferably CH3.

[0029] In an advantageous embodiment, the aromatic hydrocarbon compound A1 comprises at least two aromatic rings having a single hydroxyl functional group, and it should be understood that one ortho position of each aromatic ring having a single hydroxyl functional group is unsubstituted.

[0030] In another advantageous embodiment, the aromatic hydrocarbon compound A1 is selected from bisphenol A, lignin, or a mixture of these compounds.

[0031] I. 2-Aromatic compound A2 In one embodiment of the invention, the second component of the thermosetting resin is an aromatic compound A2, which comprises a single phenol that is unsubstituted or substituted with a single alkyl or a single alkenyl group.

[0032] Advantageously, the phenol optionally substituted with a single alkyl group is selected from phenol, o-cresol, m-cresol, p-cresol, or mixtures of these compounds.

[0033] Advantageously, phenols substituted with a single alkenyl group are coumarol of the following formula. .

[0034] I. 3-Aromatic compound A3 In an embodiment of the present invention, the third basic component of the thermosetting resin is compound A3, wherein compound A3 is selected from formaldehyde monomer, trioxymethylene, paraoxymethylene and trioxane.

[0035] I.4 Preparation of Additive-Waterborne Adhesive Compositions The aqueous adhesive compositions according to the invention may naturally contain all or part of the additives commonly used in aqueous adhesive compositions, such as those used in conventional phenolic plastic adhesives; reference will be made to, for example, alkalis (e.g., ammonia, sodium hydroxide, potassium hydroxide, or ammonium hydroxide), dyes, fillers (e.g., carbon black, silica, chalk, olive pomace, or any other natural filler), antioxidants or other stabilizers, thickeners (e.g., carboxymethyl cellulose), or gelling agents (e.g., gelatin) that can increase the viscosity of the composition. Additives that can alter the setting time or gel time and open time of the resin will also be mentioned. As those skilled in the art will understand, setting time or gel time is the length of time during which the resin can be applied to its substrate, and open time is the length of time during which the resin can be left exposed to the open air after application to its substrate without adversely affecting subsequent bonding with complementary substrates. Setting time or gel time and open time are particularly dependent on temperature, pressure, or resin concentration.

[0036] Typically, during the resin preparation process, the components of the thermosetting resin are not mixed in a predetermined order, but advantageously, water is mixed first with aromatic hydrocarbon compound A1, then sodium hydroxide, then aromatic compound A2, and then compound A3.

[0037] Thermosetting resins are prepared at pH values ​​between 8 and 14, more preferably between 9 and 12.

[0038] Therefore, thermosetting resins are obtained by mixing them in an alkaline solvent with a pH preferably between 8 and 14, more preferably between 9 and 12, as follows: - Aromatic hydrocarbon compound A1; - Aromatic polyphenols A2; and - Compound A3.

[0039] The amount of unsubstituted or monoalkyl-substituted phenol or at least one aromatic hydrocarbon compound A2 will be adjusted according to the target viscosity desired by those skilled in the art. Typically, the weight ratio of the aromatic compound A2, in which the phenol is unsubstituted or monoalkyl-substituted, to the aromatic hydrocarbon compound A1, described as a poly-monophenol, will be between 0% and 24% (excluding the upper limit), preferably between 0% and 20% of the aromatic compound A2, and more preferably between 0% and 11%.

[0040] The concentration of the composition can be adjusted according to its specific application (open time, viscosity).

[0041] Advantageously, in the final aqueous adhesive composition thus prepared, the solid content of the thermosetting resin according to the invention ranges from 10% to 90% by weight of the solids of the adhesive composition, more preferably from 15% to 75% by weight, and even more preferably from 20% to 50% by weight of the solids of the adhesive composition.

[0042] In cases where a higher viscosity is required for the final application of the adhesive composition, those skilled in the art will know how to adjust the final viscosity characteristics of the adhesive composition by adding a thickener or any type of known filler (e.g., olivine powder and / or chalk).

[0043] The composition will be ready for immediate use, or stored at ambient temperature (23°C) prior to its final use, typically with a curing time that can vary from one hour to several hours (in fact, even several days). Those skilled in the art will determine the possible storage time based on the concentration of the composition.

[0044] Preferably, the water content of the aqueous adhesive composition ranges from 10% to 90% by weight, more preferably from 25% to 85% by weight, and even more preferably from 50% to 80% by weight.

[0045] The term "total solids content of the adhesive composition" is understood to mean the ratio of the weight of the residue obtained after drying the adhesive composition to the weight of the adhesive composition before drying.

[0046] The term "solids content of thermosetting resin" is understood to mean the ratio of the weight of the thermosetting resin obtained after drying the adhesive composition to the weight of the adhesive composition before drying.

[0047] The contents of these two solids were measured according to standard NF EN 827 (March 2006).

[0048] The term "water content of an aqueous adhesive composition" is understood to mean the weight of water relative to the total weight of the adhesive composition.

[0049] II - Adhesive components of the present invention II.1 - Definition; Example As shown above, the present invention also relates to the use of the aqueous adhesive composition described above for bonding at least two cellulose-based elements (advantageously at least two elements made of wood).

[0050] Therefore, the adhesive assembly for two elements according to the present invention comprises a layer of an aqueous adhesive composition as described above for connecting the two elements to each other.

[0051] In a preferred embodiment, both elements are made of wood.

[0052] The term "timber" is understood to refer to plant tissue derived from woody plants. Examples of plant tissue include tree trunks, branches, and roots. For example, woody plants that produce plant tissue include oak, chestnut, ash, walnut, beech, poplar, cedar, pine, olive, alder, or birch.

[0053] Adhesives can also be used to bond components made of materials other than wood, such as plastic materials (e.g., thermosetting or thermoplastic materials), fabrics, inorganic materials, or mixtures of these materials (including wood).

[0054] The term "component" is understood to mean any integral part or particle. Examples of wood components are boards intended to form plywood assemblies, strips intended to form slat assemblies, particles (such as wood chips, sawdust, wood flour, or wood flakes) intended to form particleboard assemblies (whether the particles are oriented or not), fibers (such as high-density fiberboard or medium-density fiberboard) intended to form fiber assemblies, and solid wood chips (also known as logs) intended to form components such as furniture or structures.

[0055] Advantageously, the components made of wood can be wood veneer, wood strips, wood fibers, wood particles, or mixtures of these.

[0056] II.2 Preparation of Adhesive Components The adhesive assembly of the present invention can be prepared according to a method for bonding at least two cellulose-based elements (advantageously two elements made of wood), wherein: - Apply a layer of the aqueous adhesive composition according to the invention to at least one element, and - Components are connected to each other through layers of a water-based adhesive composition.

[0057] The step of applying the adhesive composition to an element or said element can be carried out by any suitable method (in particular by any known coating technique, such as spraying, dipping, injection under pressure, or a combination of one or more of these techniques).

[0058] For example, for wood veneer, a preferred application range is 50 gm. -2 Up to 400 gm -2 70 gm is preferred -2 Up to 300 gm -2 The content of the water-based adhesive composition. Those skilled in the art will know how to adapt the unit area weight of the water-based adhesive composition to its wood-based components and itself.

[0059] Advantageously, a curing step is performed after the application of the aqueous adhesive composition, wherein curing is carried out by steam curing, curing by contact with the plate of a curing press, or high-frequency curing.

[0060] Following the application of the adhesive composition, a curing step is performed: depending on the target application, the bonded assembly is heated to a temperature ranging from 30°C to 250°C, preferably 50°C to 200°C, and most preferably 80°C to 160°C. This heat treatment aims to remove any solvents or water and to crosslink the thermosetting resin. Depending on the application, the heat treatment can be performed in two steps: a first heat treatment aims to remove any solvents or water, and a second heat treatment aims to complete the crosslinking of the thermosetting resin.

[0061] In the first embodiment, the elements connected by the adhesive composition undergo a steam curing step, advantageously at a temperature greater than or equal to 100°C.

[0062] In the second embodiment, the elements connected by the adhesive composition undergo a curing step by contact with a plate of a curing press, advantageously at a temperature greater than or equal to 80°C.

[0063] In the third embodiment, the elements connected by the adhesive composition undergo a high-frequency curing step, with the high frequency advantageously ranging from 300 GHz to 300 MHz.

[0064] Preferably, the adhesive assembly is held under pressure, for example, in the range up to 18 kg·cm. -2 More preferably, the pressure holding step is performed simultaneously with the heating step.

[0065] The duration of the heating and / or pressure holding steps varies from minutes to hours, depending on the circumstances, and particularly with the temperature-pressure pair used.

[0066] In a preferred embodiment, both components to be assembled are made of wood.

[0067] Where appropriate, those skilled in the art will know how to adjust the temperature and duration of the above-described heat treatment according to the specific conditions under which the invention is carried out (in particular, the exact properties of the components). In particular, it will be advantageous for those skilled in the art to scan the treatment temperature and duration and the weight per unit area of ​​the aqueous adhesive composition, thereby attempting to find, through a continuous process, the operating conditions that produce optimal adhesion and viscosity results for each specific embodiment of the invention.

[0068] III - Embodiments and Comparative Tests of the Invention These tests demonstrate that the bonding of two wooden components using the aqueous adhesive composition according to the invention can achieve an adhesion level greater than 1 MPa.

[0069] For this purpose, seven aqueous adhesive compositions (hereinafter referred to as B-1, B-2, B-3, B-4, B-5, B-6, and B-7) have been prepared according to the present invention. Table 1 below shows their formulations (expressed as weight percentages). The amounts listed in the table are the amounts of the components in a dry state related to a total of 100 parts by weight of the aqueous adhesive composition (i.e., the components and water).

[0070] Adhesive composition B-1 is a composition based on formaldehyde, cork lignin and phenol.

[0071] Adhesive compositions B-2 to B-4 are compositions based on formaldehyde, hardwood lignin, and phenol.

[0072] Adhesive composition B-3 is a composition based on formaldehyde, cork lignin and ethylphenol.

[0073] Adhesive composition B-5 is a composition based on formaldehyde, bisphenol A and phenol.

[0074] Adhesive composition B-6 is a composition based on formaldehyde, eucalyptus resin and phenol.

[0075] Adhesive composition B-7 is a composition based on formaldehyde and hardwood lignin.

[0076] Scheme for preparing aqueous adhesive compositions Examples of schemes for preparing adhesive compositions are as follows: Pour water into a glass container of suitable size for the final solution volume. Add the poly-monophenol derivative. Stir using a mechanical stirrer at a speed that allows for good dispersion of the poly-monophenol derivative. Add sodium hydroxide solution, followed by the monophenol derivative. Stir for 5 minutes to 1 hour until the poly-monophenol derivative dissolves. Add formalin to the aforementioned solution. Heat the solution to a temperature between 20°C and 80°C and continue stirring for 5 minutes to 1 hour. At the end of this time, while the resin solution is still relatively hot, additives (e.g., fillers) can be added, or the resin solution can be cooled to ambient temperature (e.g., 25°C) before introducing additives (e.g., fillers).

[0077] Another example of a scheme for preparing an adhesive composition is as follows: Pour water into a glass container of suitable size for the final solution volume. Add the poly-monophenol derivative. Stir using a mechanical stirrer at a speed that allows for good dispersion of the poly-monophenol derivative. Add sodium hydroxide solution. Heat the solution to a temperature between 20°C and 80°C. Add the monophenol derivative, then add formaldehyde to the aforementioned solution. Continue stirring for a period between 5 minutes and 1 hour. At the end of this time, while the resin solution is still relatively hot, additives (e.g., fillers) can be added, or the resin solution can be cooled to ambient temperature (e.g., 25°C) before introducing additives (e.g., fillers).

[0078] In one embodiment, aromatic compound A1 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 60 minutes to homogenize it (e.g., at 250 rpm). Then, compound A2 is added, and the mixture is stirred for, for example, 1 to 60 minutes to homogenize it (e.g., at 250 rpm). Then, compound A3 is added. The resulting mixture is stirred at a temperature ranging from 20°C to 90°C for 1 to 60 minutes. The aforementioned technical filler is added to the composition. Depending on the components added (which those skilled in the art will know how to determine), stirring is carried out at ambient temperature for a time between 5 and 15 minutes. At the end of this time, the aqueous adhesive composition is ready for use.

[0079] Table 1 below provides examples of the compositions according to the present invention: [Table 1] (1) Soft lignin with MW=7000 g / mol, particle size of 14 μm and ash content of 1.5% (from Stora Enso). (2) Hardwood lignin with MW=5000 g / mol, particle size of 7 μm and ash content of 3.4% (extracted from black liquor from Fibre Excellence according to Valmet’s lignoboost protocol). (3) Eucalyptus pectin with MW=4000 g / mol, particle size of 7 μm and ash content of 1.6% (from Fibria). (4) Bisphenol A (from Sigma Aldrich); (5) Phenol (from Sigma Aldrich; purity >99%) (6) Ethylphenol (from Sigma Aldrich); (7) Formaldehyde (from Sigma Aldrich; purity >99%) (8) Sodium hydroxide (from Aldrich; diluted to 30%).

[0080] Viscosity test After preparing various aqueous adhesive compositions, the viscosity was measured at various time intervals. Viscosity was measured using a Brookfield / Spindle viscometer of the type selected based on the target viscosity, following this procedure: the sample was transferred to a temperature-controlled chamber up to approximately 150 ml (internal beaker graduations), avoiding the formation of air bubbles; depending on the initial temperature of the composition, the sample was allowed to stand for a specified time (i.e., 1 to 20 minutes) to allow it to self-regulate to the measurement temperature of 20°C; the spindle was rotated at a speed of, for example, 60 rpm; the spindle was allowed to stabilize (1 minute) before the first reading; and the result (viscosity in cP) was read on the digital display.

[0081] Table 2 below summarizes the results of tests performed on the composition.

[0082] Scheme for preparing samples The quality of the bond between wooden components is determined by a test in which the force required to separate the two wooden components from each other is measured by breaking the layer that connects the two components.

[0083] More specifically, each sample comprises three woody elements, in this case, elements with a density equal to 0.83 g / cm³. -3 Made of beech wood, each specimen has an overall parallelepiped shape measuring 17 cm × 17 mm × 2.5 mm. A layer of water-based adhesive composition is applied to the entire width of the first and third wooden elements on one side. The three elements are then joined together by layers of the composition applied to the first and third wooden elements. Therefore, the total adhesive-coated surface area of ​​the specimen formed from the three wooden elements is 225 cm². 2 For example, the composition of the resulting sample is cured at 160°C for 300 seconds.

[0084] At the end of curing, the specimen, which consists of three elements bonded together by adhesive, is placed in the fixture of a tensile testing machine and then subjected to tensile testing at a given rate and a given temperature (e.g., in this case, at 1.5 mm / min and 20 °C).

[0085] The specimens were cut in accordance with standard NF EN 326.1 (1994) "Wood paneling - sampling, cutting and inspection - Part 1: sampling and cutting of specimens and expression of test results".

[0086] The bond strength is characterized by measuring the "pull-out" strength (adhesive performance in MPa) at which the three components separate from each other by breaking the adhesive layer. Any pull-out value greater than or equal to 1 MPa is considered good.

[0087] The viscosity of the adhesive composition at 20°C was characterized over time (in centipoise), and the gel time is shown in the table below.

[0088] The gel time is defined by the abrupt change in viscoelastic properties, which corresponds to the formation of a macromolecular network within the material; the gel time of phenolic resins is determined according to the scheme of standard ISO 9396:1997.

[0089] The results of the tests performed on the specimens are summarized in Table 2 below.

[0090] [Table 2] The compositions according to the present invention shown in Table 1 can be used to prepare resins with viscosity initially varying with the matrix composition but always less than 50,000 cP. These viscosities are low enough to be compatible with a variety of industrial bonding systems. Those skilled in the art will be able to adjust the formulation using their own methods.

[0091] Furthermore, it can be seen that the gelation time for all samples at 100°C is less than 60 minutes. These performance levels allow the composition to be adapted to industrial limitations.

[0092] In summary, the results of these various tests clearly demonstrate that the adhesive composition according to the invention constitutes an advantageous alternative to the use of conventional adhesive compositions, in which the aromatic molecules containing a single phenol are significantly reduced or even eliminated.

[0093] The present invention is not limited to the above-described embodiments.

Claims

1. An aqueous adhesive composition, characterized in that, The aqueous adhesive composition comprises a thermosetting resin, the thermosetting resin being based on: - At least one aromatic hydrocarbon compound A1, said aromatic hydrocarbon compound A1 comprising at least one aromatic hydrocarbon compound containing at least two aromatic rings, said aromatic rings having a single hydroxyl functional group, and it should be understood that at least one of the ortho or para positions of the hydroxyl functional group of each aromatic ring is unsubstituted. - At least one aromatic compound A2, said aromatic compound A2 comprising a single phenol, said phenol being unsubstituted or substituted with a single alkyl or a single alkenyl group; and - At least one formaldehyde compound A3; The aromatic compound A2 is present in a solid weight content of less than or equal to 0.18% of the adhesive composition, wherein the solid weight content of A2 is calculated by dividing the weight of compound A2 by the total solid weight of the adhesive composition.

2. The composition according to the preceding claim, wherein, The aromatic compound A2 is present in a solid weight content of 0 in the adhesive composition.

3. The composition according to any one of the preceding claims, wherein, The aromatic hydrocarbon compound A1 corresponds to the general formula (X): ， Where Y1 represents alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl, or alkenyl groups, which are substituted, and Y2 and Y3 are the same or different, and represent H or ether groups.

4. The composition according to the preceding claim, wherein, Y2 and Y3 are located ortho to the hydroxyl functional group and represent H or OY4, wherein Y4 represents alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl or alkenyl, preferably CH3.

5. The composition according to claim 3 or 4, wherein, The aromatic hydrocarbon compound A1 comprises at least two aromatic rings, each aromatic ring having a single hydroxyl functional group. It should be understood that one adjacent position of each aromatic ring having a single hydroxyl functional group is unsubstituted.

6. The composition according to claim 3 or 4, wherein, The aromatic hydrocarbon compound A1 is selected from bisphenol A, lignin, or a mixture of these compounds.

7. The composition according to any one of claims 1 to 6, wherein, The unsubstituted or monoalkyl-substituted phenol A2 is selected from phenol, o-cresol, m-cresol, p-cresol, or mixtures of these compounds.

8. The composition according to any one of claims 1 to 6, wherein, Phenol A2 substituted with a single alkenyl group is either coumarol or phenol.

9. The composition according to any one of the preceding claims, wherein, Compound A3 is selected from monomeric formaldehyde, trioxymethylene, paraoxymethylene and trioxane.

10. The composition according to any one of the preceding claims, wherein, The aqueous adhesive composition is obtained by mixing in an alkaline solvent, preferably between pH 8 and 14, more preferably between pH 9 and 12, as follows: - Aromatic hydrocarbon compound A1; - Aromatic compound A2; and - Compound A3.

11. The adhesive composition according to any one of claims 1 to 10 is used for bonding at least two cellulose-based elements, advantageously at least two elements made of wood.

12. A method for bonding at least two cellulose-based elements, advantageously two elements made of wood, wherein: - Applying a layer of the aqueous adhesive composition according to any one of claims 1 to 10 to at least one element, and - The components are connected to each other through layers of the water-based adhesive composition.

13. The method according to the preceding claim, wherein, A curing step is performed after the application of the aqueous adhesive composition, wherein curing is carried out by steam curing, curing by contact with the plate of a curing press, or high-frequency curing.

14. An adhesive assembly for two elements, the elements being advantageously made of wood, the adhesive assembly comprising a layer of an aqueous adhesive composition according to any one of claims 1 to 10 for attaching at least one element to the other element.

Images