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EP-4739720-A1 - AQUEOUS ADHESIVE COMPOSITION COMPRISING A THERMOSETTING RESIN AND A UREA DERIVATIVE

EP4739720A1EP 4739720 A1EP4739720 A1EP 4739720A1EP-4739720-A1

Abstract

The invention relates to an aqueous adhesive composition, comprising 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, the other being an aldehyde function or a hydroxymethyl function; - at least one aromatic polyphenol A2 comprising at least one aromatic ring bearing at least two hydroxyl functions in the meta position relative to one another, the two positions ortho to at least one of the hydroxyl functions being unsubstituted; and a compound (III): R3NH-C=X-N(R1R2) in which each group R1, R2, R3 represents, independently of one another, an alkyl, alkenyl, aryl, arylalkyl, alkylaryl or cycloalkyl group or hydrogen, X represents S, O or N-R4 with R4 representing an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group or compound (III) is melamine or uracil; with compound (I) being at a weight content of solids of the aqueous adhesive composition ranging from 0.003 to 0.160.

Inventors

  • PATAUT, Gaël
  • DOISNEAU, David
  • FERNEZ, Quentin

Assignees

  • COMPAGNIE GENERALE DES ETABLISSEMENTS MICHELIN

Dates

Publication Date
20260513
Application Date
20240617

Claims (15)

  1. 1. Aqueous adhesive composition, characterized in that it comprises a thermosetting resin based on: - at least one aromatic compound A1 comprising at least one aromatic nucleus carrying 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; - at least one aromatic polyphenol A2 comprising at least one aromatic nucleus bearing at least two hydroxyl functions in meta position relative to each other, the two ortho positions of at least one of the hydroxyl functions being unsubstituted; and in that the aqueous adhesive composition comprises a compound (III): in which each group R1, R2, R3 represents, independently of one another, an alkyl, alkenyl, aryl, arylalkyl, alkylaryl, cycloalkyl or hydrogen group, X represents S, O or N-R4 with R4 representing an alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl group or the compound (III) is melamine or uracil; with the compound (III) being at a mass content of dry extract of the aqueous adhesive composition ranging from 0.003 to 0.160.
  2. 2. Composition according to the preceding claim, in which the compound (III) is at a mass rate of dry extract of the adhesive composition less than or equal to 0.150, preferably less than or equal to 0.100.
  3. 3. Composition according to any one of the preceding claims, in which the compound (III) is at a mass content of dry extract of the adhesive composition greater than or equal to 0.004.
  4. 4. Composition according to any one of the preceding claims, in which the compound (III) is urea.
  5. 5. Composition according to any one of the preceding claims, in which the aromatic compound A1 corresponds to the general formula (II): where B and C represent CHO or CH2OH respectively, X represents O, NR1, NO, S, SO, SO2, SR2R3, Ri represents hydrogen, an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group, R2, R3 each represent, independently of one another, hydrogen, an alkyl, aryl, arylalkyl, alkylaryl or cycloalkyl group.
  6. 6. Composition according to any one of the preceding claims, in which the aromatic compound A1 corresponds to the general formula (H'a1) or (H'a2): (ll’at) (H’a2)
  7. 7. Composition according to any one of the preceding claims, in which the aromatic nucleus of the aromatic polyphenol A2 carries three hydroxyl functions in the meta position relative to each other.
  8. 8. Composition according to any one of the preceding claims, in which the aromatic polyphenol A2 is chosen from the group consisting of resorcinol, phloroglucinol, 2,2',4,4'-tetrahydroxydiphenyl sulfide, 2,2',4,4 - tetrahydroxybenzophenone, and mixtures of these compounds, advantageously phloroglucinol.
  9. 9. Composition according to any one of the preceding claims, in which the aqueous adhesive composition is obtained by mixing: in a first phase a thermosetting resin by mixing: - of the aromatic compound A1, and - aromatic polyphenol A2; in a basic solvent preferably having a pH of between 7 and 14, more preferably between 9 and 12 to obtain a thermosetting resin; and after mixing the resin and the compound (III) is added at a mass rate of dry extract of the aqueous adhesive composition ranging from 0.003 to 0.160 to obtain the aqueous adhesive composition.
  10. 10. Composition according to any one of the preceding claims, comprising in in addition to an ammonium salt at a mass content of dry extract of the aqueous adhesive composition ranging from 0.001 to 0.050.
  11. 11. Composition according to the preceding claim in which the ammonium salt is chosen from ammonium chloride, ammonium fluoride, ammonium bromide, ammonium iodide, phosphorus-based ammonium derivatives, sulfur-based ammonium derivatives, organic acid-based ammonium derivatives, carbonate ammonium derivatives, nitrogen-based ammonium derivatives and mixtures of these compounds and preferably the ammonium salt is ammonium chloride.
  12. 12. Use of an adhesive composition according to any one of claims 1 to 11 for bonding at least two cellulosic elements, advantageously at least two wooden elements.
  13. 13. Method of bonding at least two cellulose elements, advantageously two wooden elements, in which: - a layer of the aqueous adhesive composition according to any one of claims 1 to 11 is applied to at least one of the elements, and, - the elements are joined together using a layer of aqueous adhesive composition.
  14. 14. Method according to the preceding claim, in which a cooking step is carried out after the step of applying the aqueous adhesive composition, in which the cooking is carried out by cooking with water vapor, cooking by contact with the plates of a cooking press or cooking by high frequency.
  15. 15. Glued assembly of two elements, advantageously made of wood, comprising a layer of the aqueous adhesive composition according to any one of claims 1 to 11 joining at least one of the elements to the other.

Description

AQUEOUS ADHESIVE COMPOSITION COMPRISING A THERMOSETTING RESIN AND A UREA DERIVATIVE [0001] The field of the present invention relates to aqueous adhesive compositions intended to adhere elements, the use and the method of manufacturing such a composition, the method of assembling elements using these compositions as well as the assemblies manufactured using these compositions. [0002] Phenoplasts or "phenol-formaldehyde resins" (abbreviated PF) are derived from formaldehyde and phenol. Since phenol is a molecule with several reactive sites, a three-dimensional network is ultimately formed. Phenoplasts are used in particular as adhesives, for example for the manufacture of chipboard or composite materials reinforced with glass fibers, textile fibers, etc. [0003] In the field of wood, a phenol-aldehyde type composition is described in US2360376. This composition comprises a phenol-aldehyde resin based on formaldehyde and phenol. The molar ratio of formaldehyde to phenol is in a range of values from 2 to 3.5. This composition is used in a process for bonding plywood articles comprising several wooden plies. During this process, one or more plies are coated with a layer of the composition, the plies are joined together via the layer of composition and the plies thus joined are pressure-cured. The bonded assembly thus obtained has high cohesion thanks to the excellent adhesive properties of the composition. [0004] However, the use of formaldehyde (or formalin), which is moreover in excess compared to phenol, leads to the release of formaldehyde not only during pressure cooking but also during storage and use of the bonded assembly. However, due to recent changes in regulations, in particular European regulations on this type of compound, it is desired to limit as much as possible, or even eliminate the use of formaldehyde or formaldehyde precursors. [0005] In its application WQ2017/168109, the Applicant proposed aqueous adhesive compositions for bonding wood, comprising a thermosetting resin based on phloroglucinol and 5-(hydroxymethyl)-furfural, having high adhesive properties and free of formaldehyde. [0006] However, the cold stability, i.e. at room temperature, of phenolic resins is an important characteristic to enable the transport and storage of the resins before their use in adhesive composition. Greater cold stability will enable the resin to be transported for longer or even stored for longer. It is all the more interesting to be able to obtain this greater cold stability without affecting the hot reactivity of the composition and its bonding qualities. [0007] Also known from the state of the art are aqueous adhesive compositions as described in EP3366468, EP3366713 and EP3436540. [0008] The aim of the invention is to provide an aqueous adhesive composition, comprising a thermosetting resin, having high adhesive properties, free of formaldehyde, and offering greater cold stability than the adhesive composition of document WO2017/168109 without penalizing the bonding quality of the adhesive composition and thus providing greater flexibility of use. [0009] However, during its research, the Applicant discovered an aqueous adhesive composition not using free formaldehyde, more stable when cold, which makes it possible to meet the above objective. [0010] Thus, an object of the invention relates to an aqueous adhesive composition comprising a thermosetting resin based on: - at least one aromatic compound A1 comprising at least one aromatic nucleus carrying 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; - at least one aromatic polyphenol A2 comprising at least one aromatic nucleus bearing at least two hydroxyl functions in meta position relative to each other, the two ortho positions of at least one of the hydroxyl functions being unsubstituted; and in that the aqueous adhesive composition comprises a compound (III): in which each group R1, R2, R3 independently represents an alkyl, alkenyl, aryl, arylalkyl, alkylaryl, cycloalkyl or hydrogen group, X represents S, O or N-R4 with R4 representing an alkyl, aryl, arylalkyl, alkylaryl, cycloalkyl group or the compound (III) is melamine or uracil; with the compound (III) being at a mass content of dry extract of the aqueous adhesive composition ranging from 0.003 to 0.160. [0011] By dry extract rate of compound (III), we mean the ratio between the mass of compound (III) and the mass of dry extract of the adhesive composition. [0001] The Applicant thus hypothesizes that the addition of a compound (III) as a stabilizer at a given rate will make it possible to increase the cold stability without, however, altering the reactivity of the aqueous adhesive composition or the bonding qualities of the composition. This will result in an increase in the lifetime of the resin at a given temperature here at a temperature above 23°C for example. Thus this i