WO2021078836A1 - Biobased adhesive compositons - Google Patents

Biobased adhesive compositons Download PDF

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Publication number
WO2021078836A1
WO2021078836A1 PCT/EP2020/079699 EP2020079699W WO2021078836A1 WO 2021078836 A1 WO2021078836 A1 WO 2021078836A1 EP 2020079699 W EP2020079699 W EP 2020079699W WO 2021078836 A1 WO2021078836 A1 WO 2021078836A1
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Prior art keywords
polysaccharide
adhesive
composition
oxidized
water
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PCT/EP2020/079699
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French (fr)
Inventor
Quentin CHARLIER
Michaël LECOURT
Sandra TAPIN-LINGUA
Adrien SORANZO
Laurent Heux
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Centre National De La Recherche Scientifique
Institut Technologique Fcba
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Application filed by Centre National De La Recherche Scientifique, Institut Technologique Fcba filed Critical Centre National De La Recherche Scientifique
Priority to EP20792992.8A priority Critical patent/EP4048705A1/en
Publication of WO2021078836A1 publication Critical patent/WO2021078836A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J101/00—Adhesives based on cellulose, modified cellulose, or cellulose derivatives
    • C09J101/02—Cellulose; Modified cellulose
    • C09J101/04—Oxycellulose; Hydrocellulose
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
    • C08B15/005—Crosslinking of cellulose derivatives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
    • C08B15/02—Oxycellulose; Hydrocellulose; Cellulosehydrate, e.g. microcrystalline cellulose
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J103/00—Adhesives based on starch, amylose or amylopectin or on their derivatives or degradation products
    • C09J103/02—Starch; Degradation products thereof, e.g. dextrin
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J105/00—Adhesives based on polysaccharides or on their derivatives, not provided for in groups C09J101/00 or C09J103/00

Definitions

  • the present invention relates to bio-based adhesive compositions.
  • the present invention relates to adhesive compositions, their manufacturing processes and their applications, in particular in the form of wood particle board.
  • aminoplast, phenoplast and emulsion (vinyl, polyurethane) glues are known. These systems can be separated into two categories: formaldehyde-based adhesives (setting chemically via crosslinking), and emulsion adhesives (“physical” setting via solvent evaporation). These products are mainly petroleum-based and, in the case of formaldehyde-based glues, are subject to the problem of the release of VOCs during the synthesis of resins, during the manufacture of panels and during their use. These characteristics are particularly penalizing in the wood panel sector because the resins constitute between 5 and 30% by mass of the finished product.
  • the first category of aqueous glues includes aminoplasts (urea / formalin, melamine / urea / formalin, melamine / formalin), phenolic (phenol / formalin) and resorcinol (resorcinol / formalin and resorcinol / phenol / formalin) glues.
  • aminoplast glues are the most widespread because of their limited cost and their flexibility of use.
  • reactive aqueous-based systems conventionally containing from 50% to 70% of dry matter
  • commercial products are mixtures of prepolymers whose size, structure and concentration have been adjusted to meet the reactivity and viscosity needs of the adhesive. Polymerization is generally obtained by thermal activation and / or by adding a catalyst.
  • Emulsion adhesives which are mainly vinyl, are thermoplastic adhesives.
  • Vinyl glues (called “white glues” or PVAc) are obtained by polymerization of vinyl acetate and are produced in the form of emulsions in water. Their dry matter varies between 50 and 60% and the viscosity is adjusted by adding additives. These glues are often formulated with surfactants to stabilize the emulsion. When applying the glue, the water is partly absorbed by the wood and partly evaporated. These two phenomena cause the increase in viscosity then finally setting the adhesive. These systems are less subject to the problem of VOC release than formalin-based glues.
  • Wood glues represent more than 65% by volume of glues used in the world.
  • the annual worldwide consumption of urea / formalin (UF) type adhesives is approximately 11 Mt of solid resin.
  • UF formalin
  • these resins are used in the production of adhesive for bonding particle boards, fiber boards ("Medium Density Fiberboard" - MDF), plywood and laminating adhesive for bonding, eg. ex. furniture, paneling and flush interior doors.
  • aminoplast glues The major disadvantage of aminoplast glues comes from the emission of formaldehyde. It is released during the production and use of agglomerated glued products. Environmental regulations and legislation regarding emissions of VOCs, particularly formaldehyde, within the wood products industry are important driving forces for technological change. In recent decades, emissions from panels have been reduced considerably. However, the reclassification of formaldehyde by the International Agency for Research and Control of Cancer (IARC) as "carcinogenic to humans" is forcing panel manufacturers, adhesive suppliers and researchers to develop systems that further reduce formaldehyde emissions at levels approaching those naturally occurring in wood.
  • IARC International Agency for Research and Control of Cancer
  • the purpose is to provide the oxidized polysaccharide with the properties desired for its application, such as for example its cationization or the addition of hydrophobic functions.
  • dialdehyde starch and dialdehyde cellulose in aqueous media are completely different.
  • oxidized starch (partially or totally) is in suspension in water (granular state) and exhibits specific rheological behaviors. As the temperature increases, aqueous suspensions of oxidized starch become more viscous, or even gel. This increase in viscosity diminishes over time.
  • the object of the present invention is to provide an adhesive composition which is an alternative to petroleum-based glues.
  • the object of the present invention is to solve the technical problem consisting in providing an adhesive composition which does not release volatile organic compounds (VOCs).
  • VOCs volatile organic compounds
  • the main object of the present invention is to provide a bio-based adhesive composition and its manufacturing process.
  • Another object of the present invention is to provide an adhesive composition in the form of a solution or dispersion, preferably of an aqueous solution or dispersion, or of powder.
  • the main aim of the present invention is to provide an adhesive composition having, in solution or dispersion, a high dry matter content, preferably at more than 15% m, in particular to limit the proportion of water in the adhesive composition and thus avoid possible swelling of the material to be bonded, in particular during hot bonding.
  • Another object of the present invention is to provide an adhesive composition making it possible to bond elements made from wood.
  • Another object of the present invention is to provide a process for preparing an adhesive composition from simple steps and with low environmental impact, the industrialization of which does not present any particular difficulties.
  • Another object of the present invention is to provide a process for preparing an adhesive composition with good reproducibility.
  • Another object of the present invention is to provide an adhesive composition for the manufacture of wood panels based on already existing industrial tools and not requiring any particular adaptation. Description of the invention
  • the invention relates to an adhesive composition in the form of a solution or dispersion comprising at least one polysaccharide soluble or dispersible in water comprising aldehyde functions, said solution or dispersion having a dry matter of greater than 20% m, preferably of at least 30% m and more preferably at least 40% m, expressed as a percentage by mass of dry matter relative to the total mass of the solution or dispersion.
  • water soluble polysaccharide is meant a polysaccharide soluble in distilled water at a concentration of at least 200 g / L, that is to say without particles or cloudiness visible to the naked eye. Reference is made here to polysaccharides after oxidation.
  • total mass of the solution or dispersion is understood to mean the total mass of dry and liquid matter.
  • % m refers to the percentage of dry matter relative to the total mass of the composition under consideration. The percentage of dry matter is measured by weighing a given amount of suspension before and after drying overnight at 60 ° C. It is expressed as a percentage by mass of dry matter over the total mass of the suspension.
  • the adhesive composition is in the form of a transparent solution.
  • the term “transparent” is understood to mean more particularly a composition exhibiting a transmittance greater than 80% and preferably greater than 90%.
  • the transmittance is preferably evaluated by measuring optical density using a UV-Visible spectrometer
  • the invention also relates to an adhesive composition in the form of a water-soluble powder comprising at least one water-soluble polysaccharide comprising aldehyde functions, said composition in powder form being able to present a quantity of dry matter in water. greater than 20% m.
  • an adhesive composition according to the invention has a high solids content in solution or dispersion in water: greater than 20% wt, preferably at least 30% wt and more preferably at least 40%. mr.
  • a dry material is advantageously obtained after fluidization according to the process of the invention.
  • the fluidization and the dry matter content according to the invention allow the use of adhesive compositions for the manufacture of wood-based panels.
  • the invention also relates to a composition
  • a composition comprising at least one oxidized crosslinked polysaccharide, the polysaccharide before crosslinking being soluble or dispersible in water and comprising aldehyde functions forming covalent bonds crosslinking said oxidized crosslinked polysaccharide.
  • the covalent bonds crosslinking said oxidized crosslinked polysaccharide are formed during the drying of a solution or dispersion comprising said polysaccharide.
  • the invention relates in particular to all polysaccharides having a sugar unit with two vicinal alcohols in axial-equatorial or equatorial-equatorial position, groups comprising inter alia cellulose, alginates, chitosans, hyaluronic acid, schyzophyllan, scleroglucan, pullulan, starches, glucosaminoglycans, mannans and xylans.
  • the invention relates to a bio-based adhesive composition, and more preferably 100% bio-based, that is to say in which all the elements are derived from organic substances of natural and renewable origin (plants, fungi, animals. , bacteria ).
  • the periodate ion is used as an oxidant, it is advantageously recycled by using hypochlorite or ozone as a secondary oxidant, or by electrolytic methods known in the literature.
  • the polysaccharide is a cellulose, for example a microcrystalline cellulose, a Kraft paper pulp or a bisulfite pulp.
  • the process for preparing an oxidized polysaccharide according to the invention comprises an oxidation of the polysaccharide, advantageously by the periodate ion or any other reagent making it possible to obtain the cleavage of the C2-C3 bond and to produce up to 2 aldehyde functions by sugar.
  • the amount of aldehyde formed advantageously varies depending on the kinetics and / or the amount of oxidant introduced. This results in a variation in the percentage of oxidation, a magnitude characterizing the progress of the reaction, the measurement of which is detailed in the invention.
  • the polysaccharide is oxidized with an oxidizing agent.
  • the polysaccharide is oxidized by periodate ion, and preferably sodium periodate.
  • the polysaccharide is preferably dispersed or solubilized before oxidation, but can also be oxidized in the form of a "slurry” known as a "slurry” which is a mixture of polymer and water in the form of a highly concentrated paste.
  • the dispersion or solubilization preferably takes place in an aqueous phase and more preferably in water as the sole solvent.
  • the oxidation protocol is preferably the following, for example with reference to cellulose:
  • the cellulose is dispersed or solubilized in water (eg deionized or tap water) using mechanical stirring.
  • the concentrations are fixed by weighing between 0.1 and 10% m depending on the tests.
  • the sodium periodate is then added at the desired stoichiometry in a concentrated solution, and the reaction is carried out at room temperature for a minimum of 12 h.
  • the reaction medium is then purified by dialysis, filtration or by centrifugation.
  • the reaction can, for example, be characterized advantageously by its percentage of oxidation.
  • an oxime formation assay is used: The amount of aldehyde formed is measured by oxime assay. The quantity of oxidized cellulose equivalent to a dry mass of 0.1 g is weighed and placed in a 100 ml beaker. 25 mL of a 0.72 M NH2OH-HCl solution are added, the pH of which has been previously adjusted to 5.2 with sodium hydroxide (0.12 M). The reaction is carried out for 2 h with stirring and at room temperature. A white precipitate appears (formation of oxime). The solution is then titrated with 0.1 M hydrochloric acid, the equivalence is measured by returning to pH 3.2.
  • Equation 1 Calculation of the percentage of oxidation by determination by oxime formation
  • the invention also relates to a process for preparing a composition as defined according to the invention, characterized in that the process comprises an oxidation reaction of at least one polysaccharide to obtain at least one polysaccharide oxide comprising aldehyde functions, said oxidation-reduction reaction being for example carried out by sodium periodate (NalC) (oxidant).
  • NaC sodium periodate
  • the polysaccharide comprises anhydroglucose units and in that the oxidation reaction leads to the creation of two aldehyde groups at the C2 and C3 carbons of the anhydroglucose units.
  • the oxidation corresponds for example to the oxidation of the lignocellulosic fibers which consist mainly of cellulose (Scheme 1).
  • the oxidation can be carried out by different means and is defined by its percentage of oxidation, expressed as the number of saccharide units oxidized out of the total number of saccharide units.
  • the method comprises rinsing, preferably by filtration or centrifugation, of the oxidized polysaccharide.
  • Rinsing is typically done after oxidation. Rinsing is necessary in the event that unwanted species are introduced during the oxidation reaction. At this point, the oxidized polysaccharide is in unstable suspension in water.
  • the method comprises fluidization, preferably by treatment at basic pH or by heating, for example greater than 60 ° C, and preferably greater than 70 ° C, for example at 80 ° C under reflux.
  • Fluidification acts on the arrangement of the oxidized polysaccharide chains in water and advantageously makes it possible to obtain, from a wet paste, a homogeneous solution with low viscosity. Due to its structure, the oxidized polysaccharide is subject to the formation of hemiacetal bonds. For this reason, the oxidized polysaccharide cannot be reconcentrated beyond 20% m of dry extract in this state.
  • the fluidization step modifies the environment of the oxidized polysaccharide to separate these bonds, which makes it possible to obtain a homogeneous and low-viscous solution which can be reconcentrated to achieve the desired dry matter content. It is possible, for example, to achieve a dry matter content of about 50% m.
  • the fluidization takes place after the oxidation of the polysaccharide and where appropriate after rinsing.
  • the fluidization is carried out by pH treatment.
  • the oxidized polysaccharide is brought to basic pH with mechanical stirring.
  • the medium initially white and opaque, becomes more and more translucent and slightly yellowish as the suspension becomes more fluid.
  • a cylindrical disperser of the ultra-turrax type is used, in particular for breaking up the resistant aggregates. The fluidization step ends when the fibers have disappeared and the solution obtained is homogeneous.
  • the fluidization is carried out by heating.
  • the oxidized polysaccharide is heated with mechanical stirring, preferably for a time which can reach several hours (i.e. greater than 1 h). The same state changes as during a pH treatment are observed.
  • Example of fluidization conditions heating at 80 ° C. in a reflux assembly with mechanical stirring for 15 h.
  • the method comprises an adjustment increasing the dry matter of the solution or dispersion obtained after fluidization, for example by the liquid route, for example by partial or total evaporation of liquid medium, or by the dry route, for example by lyophilization. , then possible return to aqueous solution.
  • Adjustment is the step in achieving the dry matter content levels needed for the final application. Typically, adjustment takes place after thinning.
  • the system At the fluidization outlet, the system generally has a dry matter content of around 15% m for an objective of around 50% m, for example.
  • the fluidification step of the process of the invention responds to the main technological barrier of the use of oxidized polysaccharide and in particular oxidized cellulose, for application as an adhesive composition by making it possible to work at dry matter levels. very high.
  • the adjustment takes place by liquid.
  • a rotary evaporator For example, it is possible to concentrate using a rotary evaporator.
  • the adjustment takes place by the dry route. For example by freeze-drying the oxidized polysaccharide to then put it back in an aqueous medium at the desired dry matter content.
  • the method comprises drying to obtain an adhesive composition in powder form according to the invention, soluble in water and comprising at least one polysaccharide soluble in water comprising aldehyde functions.
  • the invention also relates to the use of a composition according to the invention or capable of being obtained according to a process as defined according to the invention as an adhesive.
  • the invention applies to cellulose which, after treatment according to the invention, exhibits remarkable properties as an adhesive.
  • cellulose glues we speak of cellulose glues.
  • the cellulose glues are stable at room temperature.
  • the cellulose glues can be concentrated up to 50-55% m and keep their stability in the liquid state.
  • the viscosity of a cellulose glue is about 0.1 Pa.s when it comes from bisulfite pulp and 0.25 Pa.s when it comes from kraft pulp ( Brookfield measurement, 50 rpm _1 , 25 ° C, mobile No. 4). It is obvious that these systems exhibit rheological behavior as a function of temperature, time, concentration and size / morphology of the cellulose chains / nanoparticles which are the result of oxidation and fluidization.
  • the invention also relates to the use of a composition according to the invention or capable of being obtained according to a process as defined according to the invention as an adhesive by physical setting, for example by evaporation of the solvent, and preferably in the form of a glue without additive
  • a composition according to the invention or capable of being obtained according to a process as defined according to the invention as an adhesive by physical setting, for example by evaporation of the solvent, and preferably in the form of a glue without additive
  • the evaporation of the solvent from the solution typically water
  • the solution typically water
  • the material obtained dissolves easily in water.
  • the invention also relates to the use of a composition according to the invention or capable of being obtained according to a process as defined according to the invention as adhesive by chemical setting, for example by crosslinking, for example with a crosslinking agent.
  • a crosslinking agent either of phenolic or polyphenolic origin such as acid-phenols, flavones, anthocyanins, tannins or lignins, or carrying amine functions thus forming said Schiff base, preferably the crosslinking agent is chosen from the family of polyamines, for example a diamine or melamine.
  • additives crosslinking agents having functions which can react with the aldehydes of the polysaccharide.
  • the additives which make the adhesive compositions of the invention crosslink have electron donor functions, and are chosen, for example, from: • Diamines.
  • the diamines crosslink the oxidized polysaccharide, and in particular the oxidized cellulose, by formation of Schiff's bases.
  • the reaction is immediate at room temperature even at very low stoichiometries; the reaction releases heat and results in the appearance of a solid insoluble in water. Almost all the diamines are concerned by this crosslinking (aliphatic and aromatic, molecules of at least 2 carbon size between the amine functions).
  • Melamine is a triamine-triazine which has the ability to crosslink an oxidized polysaccharide, and in particular oxidized cellulose, in the same way as diamines. Typically, adding melamine to the oxidized polysaccharide results in a stable liquid product with a controlled shelf life that crosslinks in a very short time at 100 ° C.
  • the stoichiometries concerned are 1 to 20 units of oxidized cellulose for a molecule of melamine.
  • the stability of the reaction mixture at room temperature is made possible by the poor solubility of melamine in water and its lower pKa than the diamines. These physical parameters limit the progress of the reaction.
  • the solubility of melamine improves (kinetics and limit) which eventually causes crosslinking.
  • the oxidized polysaccharide is crosslinked by an agent of phenolic or polyphenolic origin such as acid-phenols, flavones, anthocyanins, tannins or lignins.
  • an agent of phenolic or polyphenolic origin such as acid-phenols, flavones, anthocyanins, tannins or lignins.
  • the oxidized polysaccharide is crosslinked, for example by an amine and forming one of the constituents of a Schiff base.
  • the polysaccharide is soluble in water and comprises aldehyde functions reacting at least in part with a crosslinking agent thus forming said Schiff's base or the reaction product with an agent of phenolic or polyphenolic origin.
  • oxidized polysaccharide having a setting time of less than 5 minutes at 100 ° C.
  • the crosslinking agent is a diamine, which generally has a high pKa
  • their integration into water at very high concentrations makes the medium very basic (pH 10-12).
  • the reaction is immediate, regardless of the temperature.
  • acidic pH pH ⁇ 5
  • the reaction does not take place, regardless of the temperature.
  • diamines for the thermal uptake of the oxidized polysaccharide, and in particular of oxidized cellulose, is for the moment limited by the dependence on the pH of this reaction.
  • one adds to the solution comprising the diamine at least one agent which alkalinizes the medium during a rise in temperature.
  • an adhesive composition according to the invention comprises 0.5 to 25% m, typically 10 to 20% m of crosslinking agent.
  • the invention also relates to the use of a composition according to the invention or capable of being obtained according to a process as defined according to the invention, such as a dry glue.
  • the invention also relates to the use of a composition according to the invention or capable of being obtained according to a process as defined according to the invention as an aqueous adhesive.
  • the tackiness of this adhesive composition which depends on a large number of factors (viscosity, dry matter content, wettability of the fibers, reactivity of the formulation, etc.) is estimated from the mechanical measurements of stress at break according to the NF standard.
  • EN 319 made on prototype laboratory or internal cohesion samples made on industrial prototype samples and compared to a standard urea-formalin formulation.
  • the invention has the advantage of providing a composition having a high dry matter content.
  • the invention has the advantage of providing a solid composition, in powder form, which can for example be resuspended, typically just before use.
  • a dry resin powder form
  • dispersible in water before use contributes to the optimization and rationalization of the transport of raw materials.
  • the adhesive bonds particles of wood, preferably to form a panel of wood particles.
  • the adhesive compositions according to the invention can be used as such in place of adhesives based on petroleum-based aqueous bases of aminoplast, phenolplast, emulsion (vinyl, polyurethane) type in order to bond particles or fibers together.
  • the invention also relates to a material, for example panel of cellulosic materials, typically wood, and preferably panels of wood particles, comprising particles bonded with at least one composition according to the invention or capable of being obtained according to a process. as defined according to the invention.
  • a material for example panel of cellulosic materials, typically wood, and preferably panels of wood particles, comprising particles bonded with at least one composition according to the invention or capable of being obtained according to a process.
  • the material comprising particles bonded with at least one adhesive composition according to the invention also comprises melamine, for example 1 to 10% m, preferably 2 to 10% m.
  • the invention also relates to a process for manufacturing particle boards of cellulosic material, typically wood.
  • the manufacture of such panels comprises the provision of particles of cellulosic material, typically wood, not glued, and the application of an adhesive composition according to the invention on the material to glue the particles of cellulosic material and thus form a glued panel.
  • the method comprises shaping the glued panel and the application of a pressing force and heating on the glued board.
  • the pressing force and the heating are generally dependent on the thickness of the panel, the target density and the desired mechanical properties.
  • a panel comprises two types of particles, namely fine and coarse particles (eg 1/3 fine and 2/3 coarse mass ratio).
  • fine particles eg 1/3 fine and 2/3 coarse mass ratio
  • large particles are retained by a 1mm mesh screen while fine particles pass through a 1mm mesh screen, but without any limitation.
  • the particles are glued separately by batch, then shaped with, in general, first the establishment of a layer of fine particles then a layer of large particles and again a layer of fine particles, with the coarse particle layer sandwiched between the fine particle layers.
  • the internal cohesion is greater than 0.10 N / mm 2 , and preferably greater than 0.20 N / mm 2 , and more preferably greater than 0.30 N / mm 2 .
  • the invention allows the manufacture of panels based on particles of cellulosic material, typically wood, with low environmental impact and low VOC emissivity, by taking advantage of an abundant and renewable resource, without competition for food.
  • the invention allows the adhesive composition to meet the specifications of existing petroleum-based aqueous adhesives in terms of physicochemical properties.
  • the materials of the invention based on particles bonded according to the invention exhibit a much less harmful nature than those currently manufactured.
  • the material of the invention is completely made from biomass or regenerable (NalC), without products derived from the petrochemical industry, which presents an important ecological advantage.
  • Figure 1 Mechanical properties (tensile stress) of laboratory prototypes of wood panels as a function of the nature of the glue, the nature and quantity of additive (a) and the dry rate of glue (b).
  • Figure 2 Mechanical properties (internal cohesion) of industrial prototypes of wood panels depending on the nature of the glue, the amount of additive and the dry rate of glue.
  • Figure 3 Water resistance of laboratory prototypes of wood panels as a function of the level of melamine in the oxidized cellulose glue.
  • each example has a general scope.
  • the polysaccharide oxidation percentages indicated in the examples are evaluated by the oxime formation assay.
  • the cellulose is oxidized with sodium periodate according to the following protocol:
  • the oxidized cellulose is then rinsed by filtration or centrifugation.
  • the oxidized cellulose is in an unstable suspension in water.
  • the oxidized cellulose obtained according to Example 1 is brought to pH 9 (adjusted by adding NaOH) for 1 hour 30 minutes with mechanical stirring at room temperature. Once the process is complete, the medium is brought to pH 4-5 by adding HCl.
  • the medium initially white and opaque, becomes more and more translucent and slightly yellowish as the oxidized cellulose dissolves. It may be necessary to use an Ultra-T urrax cylindrical disperser to break up tough aggregates.
  • the formulation step ends when the oxidized cellulose has disappeared and the solution obtained is homogeneous.
  • the oxidized cellulose obtained according to Example 1 is heated to 80 ° C in a reflux assembly with mechanical stirring for 15 h.
  • Example 5 Dry adjustment
  • Example 2 In the dry process, it is possible to concentrate a solution obtained at the end of Example 2 or of Example 3 (dry matter of about 15% m) by lyophilizing the oxidized cellulose and obtaining a dry powder. It is possible to return the lyophilized composition in aqueous medium to the desired dry matter, typically of about 50% m.
  • the yield of material from all of these formulation steps is around 75% m (weight of final oxidized cellulose relative to the weight of cellulose initially introduced).
  • the oxidation yield of cellulose is approximately 90% m (for the 75% m of final material).
  • a composition obtained according to Example 5 is crosslinked:
  • 6.1 4 or 8 g of 15% m glue are mixed at room temperature in the presence of 435 mg of hexamethylene diamine.
  • the aldehyde / amine ratio is therefore 1/1 or 2/1 respectively, considering an oxidation percentage of 100%.
  • 6.2 3 g of 15% m glue are mixed with melamine in molar proportions ⁇ oxidized cellulose / melamine ⁇ of 9/1 in a test tube. Stir manually until the mixture is homogenized. The test tube is placed in a water bath in boiling water until crosslinking. The freezing time is timed. The solidification is checked by inserting a Pasteur pipette into the test tube containing the mixture.
  • Prototypes of wood particle boards were made from cellulose and particle glue supplied by an industrial unit. They were produced in 3 layers at laboratory and pilot-industrial scale (Table 1). The resins were deposited 5 minutes in the form of atomized drops on the particle surface using a paddle mixer with a rotating shaft at 100 r _1. The gluing of the thin elements (length ⁇ 0.5 mm on average) was carried out separately from the coarser elements (length> 0.5 mm on average). In a specific rectangular mold measuring 32x32 cm 2 or 55x55 cm 2, successive layers of particles were deposited in the following order and the following mass proportions: 1/6 fine elements, 2/3 coarser elements, 1/6 elements purposes. The particle mat was introduced into a press with platens heated to 200 ° C for at least 300 s. The panels were produced under the same conditions from conventional aminoplast glues which serve as a reference and those described in the document.
  • Table 1 Data of prototypes of wood panels made from oxidized cellulose at laboratory and industrial scale

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Abstract

The present invention relates to biobased adhesive compositions. More particularly, the present invention relates to adhesive compositions, the processes for manufacturing same and the applications thereof, in particular in the form of wood particle board. The invention relates in particular to an adhesive composition in the form of a solution or dispersion comprising at least one water-soluble or water-dispersible polysaccharide comprising aldehyde functions, said solution or dispersion having a solids content of greater the 20 wt%, preferably of at least 30 wt% and more preferably of at least 40 wt%, expressed as a weight percentage of solids relative to the total weight of the solution or dispersion.

Description

Compositions adhésives biosourcées Bio-based adhesive compositions
La présente invention concerne des compositions adhésives biosourcées. The present invention relates to bio-based adhesive compositions.
Plus particulièrement, la présente invention concerne des compositions adhésives, leurs procédés de fabrications et leurs applications, en particulier sous forme de panneau de particules de bois. More particularly, the present invention relates to adhesive compositions, their manufacturing processes and their applications, in particular in the form of wood particle board.
Etat de la technique State of the art
Parmi les compositions adhésives (ou colles) on connaît les colles aminoplastes, phénoplastes, et à émulsion (vinyliques, polyuréthane). Ces systèmes peuvent être séparés en deux catégories : colles à base de formaldéhyde (à prise chimique via réticulation), et colles à émulsion (à prise « physique » par évaporation de solvant). Ces produits sont majoritairement pétrosourcés et, dans le cas des colles à base de formaldéhyde, sont soumis au problème du relargage de COV à la synthèse des résines, à la fabrication des panneaux et lors de leur utilisation. Ces caractéristiques sont particulièrement pénalisantes dans le secteur des panneaux de bois car les résines constituent entre 5 et 30 % en masse du produit fini. Among the adhesive compositions (or glues), aminoplast, phenoplast and emulsion (vinyl, polyurethane) glues are known. These systems can be separated into two categories: formaldehyde-based adhesives (setting chemically via crosslinking), and emulsion adhesives (“physical” setting via solvent evaporation). These products are mainly petroleum-based and, in the case of formaldehyde-based glues, are subject to the problem of the release of VOCs during the synthesis of resins, during the manufacture of panels and during their use. These characteristics are particularly penalizing in the wood panel sector because the resins constitute between 5 and 30% by mass of the finished product.
La première catégorie de colles aqueuses comprend les aminoplastes (résines urée/formol, mélamine/urée/formol, mélamine/formol), les colles phénoliques (phénol/formol) et résorcines (résorcinol/formol et résorcine/phénol/formol). Parmi elles, les colles aminoplastes sont les plus répandues à cause de leur coût limité et leur flexibilité de mise en oeuvre. Ce sont des systèmes réactifs à base aqueuse (classiquement contenant de 50 % à 70 % de matière sèche), précondensés. En particulier, les produits commerciaux sont des mélanges de prépolymères dont la taille, la structure et la concentration ont été ajustées pour répondre aux besoins de réactivité et de viscosité de l’adhésif. La polymérisation est généralement obtenue par activation thermique et/ou par ajout d’un catalyseur. The first category of aqueous glues includes aminoplasts (urea / formalin, melamine / urea / formalin, melamine / formalin), phenolic (phenol / formalin) and resorcinol (resorcinol / formalin and resorcinol / phenol / formalin) glues. Among them, aminoplast glues are the most widespread because of their limited cost and their flexibility of use. These are reactive aqueous-based systems (conventionally containing from 50% to 70% of dry matter), precondensed. In particular, commercial products are mixtures of prepolymers whose size, structure and concentration have been adjusted to meet the reactivity and viscosity needs of the adhesive. Polymerization is generally obtained by thermal activation and / or by adding a catalyst.
Les colles à émulsions, qui sont principalement vinyliques, sont quant à elles des colles thermoplastiques. Les colles vinyliques (dites « colles blanches » ou PVAc) sont obtenues par polymérisation d’acétate de vinyle et sont produites sous forme d’émulsions dans l’eau. Leur matière sèche varie entre 50 et 60 % et la viscosité est ajustée par ajout d’additifs. Ces colles sont souvent formulées avec des tensio-actifs pour stabiliser l’émulsion. Lors de l’application de la colle, l’eau est en partie absorbée par le bois et en partie évaporée. Ces deux phénomènes provoquent l’augmentation de viscosité puis finalement la prise de l’adhésif. Ces systèmes sont moins soumis au problème du relargage de COV que les colles à base de formol. Emulsion adhesives, which are mainly vinyl, are thermoplastic adhesives. Vinyl glues (called “white glues” or PVAc) are obtained by polymerization of vinyl acetate and are produced in the form of emulsions in water. Their dry matter varies between 50 and 60% and the viscosity is adjusted by adding additives. These glues are often formulated with surfactants to stabilize the emulsion. When applying the glue, the water is partly absorbed by the wood and partly evaporated. These two phenomena cause the increase in viscosity then finally setting the adhesive. These systems are less subject to the problem of VOC release than formalin-based glues.
Les fabricants de produits à base de bois sont les plus grands utilisateurs d'adhésifs. Les colles à bois représentent plus de 65 % en volume des colles utilisées dans le monde. La consommation annuelle mondiale d'adhésifs de type urée/formol (UF) est d'environ 11 Mt de résine solide. En particulier ces résines sont utilisées dans la production d'adhésif pour le collage de panneaux de particules, de panneaux de fibres (« Medium Density Fiberboard » - MDF), de contreplaqué et d'adhésif de laminage pour le collage, p. ex. des meubles, des revêtements de panneaux et des portes intérieures affleurantes. Manufacturers of wood-based products are the largest users of adhesives. Wood glues represent more than 65% by volume of glues used in the world. The annual worldwide consumption of urea / formalin (UF) type adhesives is approximately 11 Mt of solid resin. In particular these resins are used in the production of adhesive for bonding particle boards, fiber boards ("Medium Density Fiberboard" - MDF), plywood and laminating adhesive for bonding, eg. ex. furniture, paneling and flush interior doors.
L'inconvénient majeur des colles aminoplastes vient de l’émission de formaldéhyde. Il est libéré lors de la production et de l'utilisation de produits collés agglomérés. La réglementation environnementale et la législation concernant les émissions de COV, en particulier le formaldéhyde, au sein de l'industrie des produits du bois sont d'importantes forces motrices des changements technologiques. Au cours des dernières décennies, les émissions dues aux panneaux ont été considérablement réduites. Cependant, le reclassement du formaldéhyde par le centre international de recherche et de lutte contre le cancer (CIRC) comme " cancérogène aux humains " oblige les fabricants de panneaux, les fournisseurs d'adhésifs et les chercheurs à mettre au point des systèmes qui réduisent davantage les émissions de formaldéhyde à des niveaux se rapprochant de celles naturelles du bois. The major disadvantage of aminoplast glues comes from the emission of formaldehyde. It is released during the production and use of agglomerated glued products. Environmental regulations and legislation regarding emissions of VOCs, particularly formaldehyde, within the wood products industry are important driving forces for technological change. In recent decades, emissions from panels have been reduced considerably. However, the reclassification of formaldehyde by the International Agency for Research and Control of Cancer (IARC) as "carcinogenic to humans" is forcing panel manufacturers, adhesive suppliers and researchers to develop systems that further reduce formaldehyde emissions at levels approaching those naturally occurring in wood.
La réaction d’oxydation des polysaccharides est beaucoup mentionnée dans la littérature. Son usage est multiple. Les polysaccharides oxydés (ou polysaccharides dialdéhydes) sont à l’étude depuis les années 50. La plupart des travaux de l’époque concernent l’amidon (amidon dialdéhyde) qui a fait l’objet de nombreux brevets et articles scientifiques. L’utilisation de la cellulose dialdéhyde est plus récente car les premiers travaux datent des années 2000. L’utilisation de cellulose oxydée pour la conception de matériaux a été envisagée de multiples manières. Il est notamment possible de greffer des molécules organiques aux carbones C2 et C3 des unités sucres par réaction de bases de Schiff entre les fonctions aldéhydes et une amine. La finalité est d’apporter au polysaccharide oxydé les propriétés désirées pour son application, comme par exemple sa cationisation ou l’ajout de fonctions hydrophobes. Les comportements de l’amidon dialdéhyde et de la cellulose dialdéhyde en milieu aqueux sont complètement différents. En effet, l’amidon oxydé (partiellement ou totalement) est en suspension dans l’eau (état granulaire) et présente des comportements rhéologiques spécifiques. Quand la température augmente, les suspensions aqueuses d’amidon oxydé deviennent plus visqueuses, voire gélifient. Cette augmentation de viscosité s’atténue avec le temps. Il arrive également que les suspensions aqueuses d’amidon oxydé (suspensions d’amidon 100 % oxydé de matière sèche de 5 à 15 %m dans des gammes de pH de 3 à 7) gélifient dans le temps à température et pression ambiante. Il n’est a priori pas possible de reconcentrer à plus de 15 %m l’amidon oxydé à cause des phénomènes de gélification. Dans le cas de la cellulose, aucune information n’est disponible car l’obtention de solution de cellulose oxydée concentrée n’est pas décrite à ce jour. The oxidation reaction of polysaccharides is mentioned a lot in the literature. Its use is multiple. Oxidized polysaccharides (or dialdehyde polysaccharides) have been under study since the 1950s. Most of the work at the time concerns starch (dialdehyde starch) which was the subject of numerous patents and scientific articles. The use of dialdehyde cellulose is more recent because the first works date from the 2000s. The use of oxidized cellulose for the design of materials has been considered in many ways. It is in particular possible to graft organic molecules to the C2 and C3 carbons of the sugar units by reaction of Schiff bases between the aldehyde functions and an amine. The purpose is to provide the oxidized polysaccharide with the properties desired for its application, such as for example its cationization or the addition of hydrophobic functions. The behaviors of dialdehyde starch and dialdehyde cellulose in aqueous media are completely different. In fact, oxidized starch (partially or totally) is in suspension in water (granular state) and exhibits specific rheological behaviors. As the temperature increases, aqueous suspensions of oxidized starch become more viscous, or even gel. This increase in viscosity diminishes over time. He It also happens that aqueous suspensions of oxidized starch (suspensions of 100% oxidized starch of dry matter from 5 to 15% m in pH ranges from 3 to 7) gel over time at ambient temperature and pressure. It is a priori not possible to reconcentrate to more than 15% m the oxidized starch because of the gelation phenomena. In the case of cellulose, no information is available because obtaining a concentrated oxidized cellulose solution has not been described to date.
Ainsi, les procédés antérieurs ne permettent pas l’obtention de polysaccharides oxydés aux concentrations désirées (matière sèche désirée) pour les applications et buts recherchés dans la présente invention. Thus, the prior methods do not make it possible to obtain oxidized polysaccharides at the desired concentrations (desired dry matter) for the applications and purposes sought in the present invention.
Buts de l’invention Aims of the invention
La présente invention a pour but de proposer une composition adhésive alternative aux colles pétrosourcées. The object of the present invention is to provide an adhesive composition which is an alternative to petroleum-based glues.
La présente invention a pour but de résoudre le problème technique consistant à fournir une composition adhésive ne relarguant pas de composés organiques volatiles (COV). The object of the present invention is to solve the technical problem consisting in providing an adhesive composition which does not release volatile organic compounds (VOCs).
La présente invention a pour but principal de fournir une composition adhésive bio- sourcée et son procédé de fabrication. The main object of the present invention is to provide a bio-based adhesive composition and its manufacturing process.
La présente invention a également pour but de fournir une composition adhésive sous forme de solution ou dispersion, de préférence de solution ou dispersion aqueuse, ou de poudre. Another object of the present invention is to provide an adhesive composition in the form of a solution or dispersion, preferably of an aqueous solution or dispersion, or of powder.
En particulier, la présente invention a pour but principal de fournir une composition adhésive présentant en solution ou dispersion une haute teneur en matière sèche, de préférence à plus de 15 %m, en particulier pour limiter la proportion en eau dans la composition adhésive et ainsi éviter un possible gonflement du matériau à coller, en particulier lors d’un collage à chaud. In particular, the main aim of the present invention is to provide an adhesive composition having, in solution or dispersion, a high dry matter content, preferably at more than 15% m, in particular to limit the proportion of water in the adhesive composition and thus avoid possible swelling of the material to be bonded, in particular during hot bonding.
La présente invention a encore pour but de fournir une composition adhésive permettant de coller des éléments issus de bois. Another object of the present invention is to provide an adhesive composition making it possible to bond elements made from wood.
La présente invention a encore pour but de fournir un procédé de préparation d’une composition adhésive à partir d’étapes simples et à faible impact environnemental dont l’industrialisation ne présente pas de difficultés particulières. Another object of the present invention is to provide a process for preparing an adhesive composition from simple steps and with low environmental impact, the industrialization of which does not present any particular difficulties.
La présente invention a encore pour but de fournir un procédé de préparation d’une composition adhésive avec une bonne reproductibilité. Another object of the present invention is to provide a process for preparing an adhesive composition with good reproducibility.
La présente invention a aussi pour but de fournir une composition adhésive pour la fabrication de panneaux de bois s’appuyant sur des outils industriels déjà existants et ne demandant pas d’adaptation particulière. Description de l’invention Another object of the present invention is to provide an adhesive composition for the manufacture of wood panels based on already existing industrial tools and not requiring any particular adaptation. Description of the invention
L’invention concerne une composition adhésive sous forme de solution ou dispersion comprenant au moins un polysaccharide soluble ou dispersible dans l’eau comprenant des fonctions aldéhydes, ladite solution ou dispersion présentant une matière sèche supérieure à 20 %m, de préférence d’au moins 30 %m et encore de préférence d’au moins 40 %m, exprimé en pourcentage massique de matière sèche par rapport à la masse totale de la solution ou dispersion. The invention relates to an adhesive composition in the form of a solution or dispersion comprising at least one polysaccharide soluble or dispersible in water comprising aldehyde functions, said solution or dispersion having a dry matter of greater than 20% m, preferably of at least 30% m and more preferably at least 40% m, expressed as a percentage by mass of dry matter relative to the total mass of the solution or dispersion.
Par « polysaccharide soluble dans l’eau » on entend un polysaccharide soluble dans l’eau distillée à une concentration d’au moins 200 g/L, c’est-à-dire sans particules ou de trouble visibles à l’œil nu. Il est fait référence ici aux polysaccharides après oxydation. By "water soluble polysaccharide" is meant a polysaccharide soluble in distilled water at a concentration of at least 200 g / L, that is to say without particles or cloudiness visible to the naked eye. Reference is made here to polysaccharides after oxidation.
En référence au pourcentage de matière sèche, on entend par « masse totale de la solution ou dispersion » la masse totale de matière sèche et liquide. L’expression « %m » fait référence au pourcentage de matière sèche par rapport à la masse totale de la composition considérée. Le pourcentage de matière sèche est mesuré par pesée d’une quantité donnée de suspension avant et après séchage une nuit à 60°C. Il est exprimé en pourcentage massique de matière sèche sur la masse totale de la suspension. With reference to the percentage of dry matter, the term “total mass of the solution or dispersion” is understood to mean the total mass of dry and liquid matter. The expression "% m" refers to the percentage of dry matter relative to the total mass of the composition under consideration. The percentage of dry matter is measured by weighing a given amount of suspension before and after drying overnight at 60 ° C. It is expressed as a percentage by mass of dry matter over the total mass of the suspension.
De préférence, la composition adhésive est sous forme de solution transparente.Preferably, the adhesive composition is in the form of a transparent solution.
Par transparent, on entend plus particulièrement une composition présentant une transmittance supérieure à 80 % et de préférence supérieure à 90 %. La transmittance est de préférence évaluée par mesure de densité optique à l’aide d’un spectromètre UV-VisibleThe term “transparent” is understood to mean more particularly a composition exhibiting a transmittance greater than 80% and preferably greater than 90%. The transmittance is preferably evaluated by measuring optical density using a UV-Visible spectrometer
L’invention concerne aussi une composition adhésive sous forme de poudre soluble dans l’eau comprenant au moins un polysaccharide soluble dans l’eau comprenant des fonctions aldéhydes, ladite composition sous forme poudre étant apte à présenter dans l’eau une quantité de matière sèche supérieure à 20 %m. The invention also relates to an adhesive composition in the form of a water-soluble powder comprising at least one water-soluble polysaccharide comprising aldehyde functions, said composition in powder form being able to present a quantity of dry matter in water. greater than 20% m.
Avantageusement, une composition adhésive selon l’invention présente une haute teneur en matière sèche en solution ou dispersion dans l’eau : supérieure à 20 %m, de préférence d’au moins 30 %m et encore de préférence d’au moins 40 %m. Une telle matière sèche est avantageusement obtenue après fluidification selon le procédé de l’invention. Advantageously, an adhesive composition according to the invention has a high solids content in solution or dispersion in water: greater than 20% wt, preferably at least 30% wt and more preferably at least 40%. mr. Such a dry material is advantageously obtained after fluidization according to the process of the invention.
Avantageusement, la fluidification et la teneur en matière sèche selon l’invention permettent l’utilisation des compositions adhésives pour la fabrication de panneaux à base de bois. Advantageously, the fluidization and the dry matter content according to the invention allow the use of adhesive compositions for the manufacture of wood-based panels.
On préfère aussi diminuer la teneur en eau de la composition adhésive pour éviter l’inconvénient de la formation de cloques dans le matériau final par collage sous pression à chaud. It is also preferred to reduce the water content of the adhesive composition to avoid the disadvantage of the formation of blisters in the final material by hot pressure bonding.
L’invention concerne encore une composition comprenant au moins un polysaccharide oxydé réticulé, le polysaccharide avant réticulation étant soluble ou dispersible dans l’eau et comprenant des fonctions aldéhydes formant des liaisons covalentes réticulant ledit polysaccharide oxydé réticulé. Typiquement, les liaisons covalentes réticulant ledit polysaccharide oxydé réticulé sont formées lors du séchage d’une solution ou dispersion comprenant ledit polysaccharide. The invention also relates to a composition comprising at least one oxidized crosslinked polysaccharide, the polysaccharide before crosslinking being soluble or dispersible in water and comprising aldehyde functions forming covalent bonds crosslinking said oxidized crosslinked polysaccharide. Typically, the covalent bonds crosslinking said oxidized crosslinked polysaccharide are formed during the drying of a solution or dispersion comprising said polysaccharide.
L’invention concerne notamment tous les polysaccharides présentant une unité sucre avec deux alcools vicinaux en position axiale-equatoriale ou equatoriale-equatoriale, groupes comprenant entre autres la cellulose, les alginates, les chitosanes, l’acide hyaluronique, le schyzophyllane, le scleroglucane, le pullulane, les amidons, les glucosaminoglycanes, les mannanes et les xylanes. The invention relates in particular to all polysaccharides having a sugar unit with two vicinal alcohols in axial-equatorial or equatorial-equatorial position, groups comprising inter alia cellulose, alginates, chitosans, hyaluronic acid, schyzophyllan, scleroglucan, pullulan, starches, glucosaminoglycans, mannans and xylans.
On préfère un polysaccharide d’origine naturelle, c’est-à-dire biosourcé. Ainsi, de préférence, l’invention concerne une composition adhésive biosourcée, et de préférence encore 100 % biosourcée, c’est-à-dire dont tous les éléments sont issus de substances organiques d’origine naturelle et renouvelables (plantes, champignons, animaux, bactéries...). Lorsqu’on utilise l’ion périodate comme oxydant, celui-ci est avantageusement recyclé par utilisation d’hypochlorite ou d’ozone comme oxydant secondaire, ou par des procédés électrolytiques connus dans la littérature. Preferred is a naturally occurring, i.e. biobased, polysaccharide. Thus, preferably, the invention relates to a bio-based adhesive composition, and more preferably 100% bio-based, that is to say in which all the elements are derived from organic substances of natural and renewable origin (plants, fungi, animals. , bacteria ...). When the periodate ion is used as an oxidant, it is advantageously recycled by using hypochlorite or ozone as a secondary oxidant, or by electrolytic methods known in the literature.
De préférence, le polysaccharide est une cellulose, par exemple une cellulose microcristalline, une pâte à papier Kraft ou une pâte bisulfite. Preferably, the polysaccharide is a cellulose, for example a microcrystalline cellulose, a Kraft paper pulp or a bisulfite pulp.
Le procédé de préparation d’un polysaccharide oxydé selon l’invention comprend une oxydation du polysaccharide, avantageusement par l’ion périodate ou tout autre réactif permettant d’obtenir le clivage de la liaison C2-C3 et de produire jusqu’à 2 fonctions aldéhydes par sucre. The process for preparing an oxidized polysaccharide according to the invention comprises an oxidation of the polysaccharide, advantageously by the periodate ion or any other reagent making it possible to obtain the cleavage of the C2-C3 bond and to produce up to 2 aldehyde functions by sugar.
La quantité d’aldéhyde formée varie avantageusement selon la cinétique et/ou la quantité d’oxydant introduite. Cela se traduit par une variation du pourcentage d’oxydation, grandeur caractérisant l’avancement de la réaction, dont la mesure est détaillée dans l’invention. The amount of aldehyde formed advantageously varies depending on the kinetics and / or the amount of oxidant introduced. This results in a variation in the percentage of oxidation, a magnitude characterizing the progress of the reaction, the measurement of which is detailed in the invention.
De préférence, on oxyde le polysaccharide par un agent oxydant. De préférence, le polysaccharide est oxydé par l’ion périodate, et de préférence le périodate de sodium. Preferably, the polysaccharide is oxidized with an oxidizing agent. Preferably, the polysaccharide is oxidized by periodate ion, and preferably sodium periodate.
Le polysaccharide est de préférence dispersé ou solubilisé avant oxydation, mais peut être également oxydé sous forme de « boue » connue sous le nom de « slurry » qui est un mélange de polymère et d’eau sous forme de pâte très concentrée. La dispersion ou solubilisation a de préférence lieu dans une phase aqueuse et de préférence encore dans de l’eau comme unique solvant. The polysaccharide is preferably dispersed or solubilized before oxidation, but can also be oxidized in the form of a "slurry" known as a "slurry" which is a mixture of polymer and water in the form of a highly concentrated paste. The dispersion or solubilization preferably takes place in an aqueous phase and more preferably in water as the sole solvent.
Le protocole d’oxydation est de préférence le suivant, par exemple en référence à la cellulose : La cellulose est dispersée ou solubilisée dans de l’eau (par exemple de l’eau déionisée ou du robinet) à l’aide d’une agitation mécanique. Les concentrations sont fixées par pesées entre 0,1 et 10 %m selon les essais. Le périodate de sodium est ensuite ajouté à la stœchiométrie voulue en solution concentrée, et la réaction est conduite à température ambiante pendant 12 h minimum. Le milieu réactionnel est ensuite purifié par dialyse, filtration ou par centrifugation. The oxidation protocol is preferably the following, for example with reference to cellulose: The cellulose is dispersed or solubilized in water (eg deionized or tap water) using mechanical stirring. The concentrations are fixed by weighing between 0.1 and 10% m depending on the tests. The sodium periodate is then added at the desired stoichiometry in a concentrated solution, and the reaction is carried out at room temperature for a minimum of 12 h. The reaction medium is then purified by dialysis, filtration or by centrifugation.
La réaction peut être par exemple caractérisée avantageusement par son pourcentage d’oxydation. On utilise selon la présente invention un dosage par formation d’oxime : La quantité d’aldéhyde formé est mesurée par dosage à l’oxime. La quantité de cellulose oxydée équivalente à une masse sèche de 0,1 g est pesée et placée dans un bêcher de 100 mL. Sont ajoutés 25 mL d’une solution de NH2OH-HCI à 0,72 M, dont le pH aura été préalablement ajusté à 5,2 par de l’hydroxyde de sodium (0,12 M). La réaction est conduite 2 h sous agitation et à température ambiante. Un précipité blanc apparaît (formation de l’oxime). La solution est ensuite titrée avec de l’acide chlorhydrique à 0,1 M, l’équivalence est mesuré par un retour à pH de 3,2. The reaction can, for example, be characterized advantageously by its percentage of oxidation. According to the present invention, an oxime formation assay is used: The amount of aldehyde formed is measured by oxime assay. The quantity of oxidized cellulose equivalent to a dry mass of 0.1 g is weighed and placed in a 100 ml beaker. 25 mL of a 0.72 M NH2OH-HCl solution are added, the pH of which has been previously adjusted to 5.2 with sodium hydroxide (0.12 M). The reaction is carried out for 2 h with stirring and at room temperature. A white precipitate appears (formation of oxime). The solution is then titrated with 0.1 M hydrochloric acid, the equivalence is measured by returning to pH 3.2.
Avec le volume d’HCI à l’équivalence, le pourcentage d’oxydation est calculé selon l’équation 1 : With the volume of HCl at equivalence, the percent oxidation is calculated using equation 1:
Equation 1 : calcul du pourcentage d’oxydation par dosage par formation d’oxime
Figure imgf000007_0001
Equation 1: Calculation of the percentage of oxidation by determination by oxime formation
Figure imgf000007_0001
Avec M cellulose = 160 g/mol (masse molaire d’une unité anhydroglucose oxydée), VHci = volume d’HCI versé à l’équivalence, CHCI = concentration d’HCI et mCeiiuiose = masse sèche de cellulose oxydée introduite. Selon un mode de réalisation on préfère un polysaccharide présentant un pourcentage d’oxydation supérieur à 50 %, et de préférence supérieur ou égal à 70 %, et de préférence encore supérieur ou égal à 80 %, exprimé en nombre d’unités saccharides oxydées sur le nombre total d’unités saccharidiques. Selon un mode de réalisation on préfère un polysaccharide présentant un pourcentage d’oxydation supérieur à 90 %. With M cellulose = 160 g / mol (molar mass of an oxidized anhydroglucose unit), V H ci = volume of HCl poured in equivalence, CHCl = concentration of HCl and m C eiiuiose = dry mass of oxidized cellulose introduced . According to one embodiment, a polysaccharide having an oxidation percentage greater than 50%, and preferably greater than or equal to 70%, and more preferably greater than or equal to 80%, expressed in number of saccharide units oxidized on the basis of one embodiment, is preferred. the total number of saccharide units. According to one embodiment, a polysaccharide having an oxidation percentage greater than 90% is preferred.
L’invention concerne également un procédé de préparation d’une composition telle que définie selon l’invention, caractérisé en ce que le procédé comprend une réaction d’oxydation d’au moins un polysaccharide pour l’obtention d’au moins un polysaccharide oxydé comprenant des fonctions aldéhydes, ladite réaction d’oxydo-réduction étant par exemple réalisée par le périodate de sodium (NalC ) (oxydant). The invention also relates to a process for preparing a composition as defined according to the invention, characterized in that the process comprises an oxidation reaction of at least one polysaccharide to obtain at least one polysaccharide oxide comprising aldehyde functions, said oxidation-reduction reaction being for example carried out by sodium periodate (NalC) (oxidant).
Selon un mode de réalisation, le polysaccharide comprend des unités anhydroglucose et en ce que la réaction d’oxydation conduit à la création de deux groupements aldéhydes aux carbones C2 et C3 des unités anhydroglucose. According to one embodiment, the polysaccharide comprises anhydroglucose units and in that the oxidation reaction leads to the creation of two aldehyde groups at the C2 and C3 carbons of the anhydroglucose units.
Selon ce mode de réalisation, l’oxydation correspond par exemple à l’oxydation des fibres lignocellulosiques qui sont constituées majoritairement de cellulose (Schéma 1). L’oxydation peut être effectuée par différents moyens et est définie par son pourcentage d’oxydation, exprimé en nombre d’unités saccharidiques oxydées sur le nombre total d’unités saccharidiques.
Figure imgf000008_0001
According to this embodiment, the oxidation corresponds for example to the oxidation of the lignocellulosic fibers which consist mainly of cellulose (Scheme 1). The oxidation can be carried out by different means and is defined by its percentage of oxidation, expressed as the number of saccharide units oxidized out of the total number of saccharide units.
Figure imgf000008_0001
Schéma 1 : Réaction d’oxydation de la cellulose De préférence, pour obtenir un produit final aux caractéristiques désirées, on préfère que l’avancement de la réaction d’oxydation du polysaccharide soit important. Scheme 1: Oxidation reaction of cellulose Preferably, to obtain a final product with the desired characteristics, it is preferred that the progress of the oxidation reaction of the polysaccharide is significant.
Selon un mode de réalisation, le procédé comprend un rinçage, de préférence par filtration ou centrifugation, du polysaccharide oxydé. According to one embodiment, the method comprises rinsing, preferably by filtration or centrifugation, of the oxidized polysaccharide.
Le rinçage est typiquement réalisé après l’oxydation. Le rinçage est nécessaire dans le cas où des espèces non désirées sont introduites lors de la réaction d’oxydation. A ce stade, le polysaccharide oxydé est en suspension instable dans l’eau. Rinsing is typically done after oxidation. Rinsing is necessary in the event that unwanted species are introduced during the oxidation reaction. At this point, the oxidized polysaccharide is in unstable suspension in water.
Selon un mode de réalisation, le procédé comprend une fluidification, de préférence par traitement à pH basique ou par chauffage, par exemple supérieur à 60 °C, et de préférence supérieur à 70 °C, par exemple à 80 °C sous reflux. La fluidification agit sur l’arrangement des chaînes de polysaccharide oxydé dans l’eau et permet avantageusement d’obtenir, à partir d’une pâte humide, une solution homogène peu visqueuse. De par sa structure, le polysaccharide oxydé est sujet à la formation de liaisons hémiacétales. Pour cette raison, le polysaccharide oxydé ne peut être reconcentré au-delà de 20 %m d’extrait sec dans cet état. De préférence, l’étape de fluidification modifie l’environnement du polysaccharide oxydé pour séparer ces liaisons, ce qui permet d’obtenir une solution homogène et peu visqueuse que l’on peut reconcentrer pour atteindre le taux de matière sèche désiré. On peut, par exemple, atteindre un taux de matière sèche d’environ 50 %m. Typiquement, la fluidification a lieu après l’oxydation du polysaccharide et le cas échéant après rinçage. According to one embodiment, the method comprises fluidization, preferably by treatment at basic pH or by heating, for example greater than 60 ° C, and preferably greater than 70 ° C, for example at 80 ° C under reflux. Fluidification acts on the arrangement of the oxidized polysaccharide chains in water and advantageously makes it possible to obtain, from a wet paste, a homogeneous solution with low viscosity. Due to its structure, the oxidized polysaccharide is subject to the formation of hemiacetal bonds. For this reason, the oxidized polysaccharide cannot be reconcentrated beyond 20% m of dry extract in this state. Preferably, the fluidization step modifies the environment of the oxidized polysaccharide to separate these bonds, which makes it possible to obtain a homogeneous and low-viscous solution which can be reconcentrated to achieve the desired dry matter content. It is possible, for example, to achieve a dry matter content of about 50% m. Typically, the fluidization takes place after the oxidation of the polysaccharide and where appropriate after rinsing.
Selon un mode de réalisation, la fluidification est réalisée par traitement pH. Typiquement, le polysaccharide oxydé est porté à pH basique sous agitation mécanique. Le milieu, initialement blanc et opaque, devient de plus en plus translucide et légèrement jaunâtre au fur et à mesure que la suspension se fluidifie. Selon une variante, on utilise un disperseur cylindrique de type ultra-turrax, notamment pour casser les agrégats résistants. L’étape de fluidification se termine quand les fibres ont disparu et que la solution obtenue est homogène. According to one embodiment, the fluidization is carried out by pH treatment. Typically, the oxidized polysaccharide is brought to basic pH with mechanical stirring. The medium, initially white and opaque, becomes more and more translucent and slightly yellowish as the suspension becomes more fluid. According to one variant, a cylindrical disperser of the ultra-turrax type is used, in particular for breaking up the resistant aggregates. The fluidization step ends when the fibers have disappeared and the solution obtained is homogeneous.
Selon un mode de réalisation, la fluidification est réalisée par chauffage. Typiquement, le polysaccharide oxydé est chauffé sous agitation mécanique, de préférence pendant un temps pouvant atteindre plusieurs heures (i.e. supérieur à 1 h) Les mêmes modifications d’état que lors d’un traitement pH sont observées. Exemple de conditions de fluidification : chauffage à 80 °C dans un montage à reflux sous agitation mécanique pendant 15 h. According to one embodiment, the fluidization is carried out by heating. Typically, the oxidized polysaccharide is heated with mechanical stirring, preferably for a time which can reach several hours (i.e. greater than 1 h). The same state changes as during a pH treatment are observed. Example of fluidization conditions: heating at 80 ° C. in a reflux assembly with mechanical stirring for 15 h.
Selon un mode de réalisation, le procédé comprend un ajustement augmentant la matière sèche de la solution ou dispersion obtenue après fluidification, par exemple par voie liquide, par exemple par évaporation partielle ou totale de milieu liquide, ou par voie sèche, par exemple par lyophilisation, puis éventuelle remise en solution aqueuse. According to one embodiment, the method comprises an adjustment increasing the dry matter of the solution or dispersion obtained after fluidization, for example by the liquid route, for example by partial or total evaporation of liquid medium, or by the dry route, for example by lyophilization. , then possible return to aqueous solution.
L’ajustement est l’étape qui permet d’atteindre les niveaux de taux de matière sèche nécessaires à l’application finale. Typiquement, l’ajustement a lieu après la fluidification. Adjustment is the step in achieving the dry matter content levels needed for the final application. Typically, adjustment takes place after thinning.
En sortie de fluidification, le système présente en général un taux de matière sèche d’environ 15 %m pour un objectif par exemple d’environ 50 %m. At the fluidization outlet, the system generally has a dry matter content of around 15% m for an objective of around 50% m, for example.
En particulier, l’étape de fluidification du procédé de l’invention répond au principal verrou technologique de l’utilisation de polysaccharide oxydé et en particulier de la cellulose oxydée, pour une application comme composition adhésive en permettant de travailler à des taux de matière sèches très élevés. In particular, the fluidification step of the process of the invention responds to the main technological barrier of the use of oxidized polysaccharide and in particular oxidized cellulose, for application as an adhesive composition by making it possible to work at dry matter levels. very high.
Selon un mode de réalisation, l’ajustement a lieu par voie liquide. Par exemple, il est possible de concentrer en utilisant un évaporateur rotatif. According to one embodiment, the adjustment takes place by liquid. For example, it is possible to concentrate using a rotary evaporator.
Selon un mode de réalisation, l’ajustement a lieu par voie sèche. Par exemple en lyophilisant le polysaccharide oxydé pour le remettre ensuite en milieu aqueux au taux de matière sèche désirée. According to one embodiment, the adjustment takes place by the dry route. For example by freeze-drying the oxidized polysaccharide to then put it back in an aqueous medium at the desired dry matter content.
Selon un mode de réalisation, le procédé comprend un séchage pour l’obtention d’une composition adhésive sous forme de poudre selon l’invention, soluble dans l’eau et comprenant au moins un polysaccharide soluble dans l’eau comprenant des fonctions aldéhydes. L’invention concerne aussi l’utilisation d’une composition selon l’invention ou susceptible d’être obtenue selon un procédé tel que défini selon l’invention comme adhésif. According to one embodiment, the method comprises drying to obtain an adhesive composition in powder form according to the invention, soluble in water and comprising at least one polysaccharide soluble in water comprising aldehyde functions. The invention also relates to the use of a composition according to the invention or capable of being obtained according to a process as defined according to the invention as an adhesive.
En particulier, l’invention s’applique à la cellulose qui présente après traitement selon l’invention des propriétés remarquables à titre d’adhésif. On parle alors par exemple selon l’invention de colles de cellulose. In particular, the invention applies to cellulose which, after treatment according to the invention, exhibits remarkable properties as an adhesive. For example, according to the invention, we speak of cellulose glues.
Avantageusement, les colles de cellulose sont stables à température ambiante. Avantageusement, les colles de cellulose peuvent être concentrées jusqu’à 50-55 %m et garder leur stabilité à l’état liquide. Avantageusement, à 45 %m de matière sèche, la viscosité d’une colle de cellulose (solution aqueuse) est d’environ 0,1 Pa.s quand issue de pâte bisulfite et 0,25 Pa.s quand issue de pâte kraft (mesure Brookfield, 50 tr.min_1, 25 °C, mobile N°4). Il est évident que ces systèmes présentent un comportement rhéologique fonction de la température, du temps, de la concentration et de la taille/morphologie des chaines/nanoparticules de cellulose qui sont le résultat de l’oxydation et de la fluidification. Selon l’invention, on préfère des solutions de polysaccharide oxydé présentant une viscosité de 0,08 à 1 Pa.s et typiquement de 0,1 à 0,5 Pa.s. Advantageously, the cellulose glues are stable at room temperature. Advantageously, the cellulose glues can be concentrated up to 50-55% m and keep their stability in the liquid state. Advantageously, at 45% m of dry matter, the viscosity of a cellulose glue (aqueous solution) is about 0.1 Pa.s when it comes from bisulfite pulp and 0.25 Pa.s when it comes from kraft pulp ( Brookfield measurement, 50 rpm _1 , 25 ° C, mobile No. 4). It is obvious that these systems exhibit rheological behavior as a function of temperature, time, concentration and size / morphology of the cellulose chains / nanoparticles which are the result of oxidation and fluidization. According to the invention, preferred are solutions of oxidized polysaccharide having a viscosity of 0.08 to 1 Pa.s and typically 0.1 to 0.5 Pa.s.
Il existe plusieurs approches pour préparer un matériau collé (ou la prise de l’adhésif) à partir des compositions de l’invention. There are several approaches to preparing a bonded material (or adhesive set) from the compositions of the invention.
L’invention concerne aussi l’utilisation d’une composition selon l’invention ou susceptible d’être obtenue selon un procédé tel que défini selon l’invention comme adhésif par prise physique, par exemple par l’évaporation du solvant, et de préférence sous forme d’une colle sans additif Sans ajout d’additif, l’évaporation du solvant de la solution (typiquement de l’eau) conduit à l’obtention d’un matériau dur et fragile. On considère qu’il y a formation d’un réseau de liaisons hémiacétales. Le matériau obtenu se dissout facilement dans l’eau. The invention also relates to the use of a composition according to the invention or capable of being obtained according to a process as defined according to the invention as an adhesive by physical setting, for example by evaporation of the solvent, and preferably in the form of a glue without additive Without adding any additive, the evaporation of the solvent from the solution (typically water) results in obtaining a hard and fragile material. It is considered that there is formation of a network of hemiacetal bonds. The material obtained dissolves easily in water.
L’invention concerne aussi l’utilisation d’une composition selon l’invention ou susceptible d’être obtenue selon un procédé tel que défini selon l’invention comme adhésif par prise chimique, par exemple par réticulation, par exemple avec un agent de réticulation soit d’origine phénolique ou polyphénoliques comme les acides-phénols, les flavones, les anthocyanes, les tanins ou les lignines, soit portant des fonctions amines formant ainsi ladite base de Schiff, de préférence l’agent de réticulation est choisi parmi la famille des polyamines par exemple une diamine ou la mélamine. The invention also relates to the use of a composition according to the invention or capable of being obtained according to a process as defined according to the invention as adhesive by chemical setting, for example by crosslinking, for example with a crosslinking agent. either of phenolic or polyphenolic origin such as acid-phenols, flavones, anthocyanins, tannins or lignins, or carrying amine functions thus forming said Schiff base, preferably the crosslinking agent is chosen from the family of polyamines, for example a diamine or melamine.
Il est également possible de considérer l’ajout d’additifs (agents de réticulation) ayant des fonctions pouvant réagir avec les aldéhydes du polysaccharide. Les additifs faisant réticuler les compositions adhésives de l’invention (colles de cellulose) présentent des fonctions donneuses d’électrons, et sont choisis par exemple parmi : • Les diamines. Les diamines font réticuler le polysaccharide oxydé, et en particulier la cellulose oxydée, par formation de bases de Schiff. En général, la réaction est immédiate à température ambiante même à des stœchiométries très faibles ; la réaction dégage de la chaleur et conduit à l’apparition d’un solide insoluble dans l’eau. Quasiment toutes les diamines sont concernées par cette réticulation (aliphatiques et aromatiques, molécules de taille au moins 2 carbones entre les fonctions amines). It is also possible to consider the addition of additives (crosslinking agents) having functions which can react with the aldehydes of the polysaccharide. The additives which make the adhesive compositions of the invention crosslink (cellulose glues) have electron donor functions, and are chosen, for example, from: • Diamines. The diamines crosslink the oxidized polysaccharide, and in particular the oxidized cellulose, by formation of Schiff's bases. In general, the reaction is immediate at room temperature even at very low stoichiometries; the reaction releases heat and results in the appearance of a solid insoluble in water. Almost all the diamines are concerned by this crosslinking (aliphatic and aromatic, molecules of at least 2 carbon size between the amine functions).
• La mélamine. La mélamine est une triamine-triazine qui possède la capacité de faire réticuler un polysaccharide oxydé, et en particulier la cellulose oxydée, au même titre que les diamines. Typiquement, l’ajout de mélamine au polysaccharide oxydé permet d’obtenir un produit liquide stable, à durée de vie contrôlée qui réticule en un temps très court à 100 °C. Les stœchiométries concernées sont de 1 à 20 unités de cellulose oxydée pour une molécule de mélamine. La stabilité du mélange réactif à température ambiante est permise par la mauvaise solubilité de la mélamine dans l’eau et son pKa plus faible que les diamines. Ces paramètres physiques limitent l’avancement de la réaction. Lors du chauffage du mélange réactif, la solubilité de la mélamine s’améliore (cinétique et limite) ce qui finit par provoquer la réticulation. En particulier, pour caractériser la réactivité, on préfère réaliser un chauffage de 5 minutes à 100 °C pour provoquer la réticulation à chaud ou lors de la redescente en température. • Melamine. Melamine is a triamine-triazine which has the ability to crosslink an oxidized polysaccharide, and in particular oxidized cellulose, in the same way as diamines. Typically, adding melamine to the oxidized polysaccharide results in a stable liquid product with a controlled shelf life that crosslinks in a very short time at 100 ° C. The stoichiometries concerned are 1 to 20 units of oxidized cellulose for a molecule of melamine. The stability of the reaction mixture at room temperature is made possible by the poor solubility of melamine in water and its lower pKa than the diamines. These physical parameters limit the progress of the reaction. When heating the reaction mixture, the solubility of melamine improves (kinetics and limit) which eventually causes crosslinking. In particular, to characterize the reactivity, it is preferred to carry out heating for 5 minutes at 100 ° C. in order to cause crosslinking when hot or when the temperature drops.
Selon un mode de réalisation, le polysaccharide oxydé est réticulé par un agent d’origine phénolique ou polyphénoliques comme les acides-phénols, les flavones, les anthocyanes, les tanins ou les lignines. According to one embodiment, the oxidized polysaccharide is crosslinked by an agent of phenolic or polyphenolic origin such as acid-phenols, flavones, anthocyanins, tannins or lignins.
Selon un mode de réalisation, le polysaccharide oxydé est réticulé par exemple par une amine et formant un des constituant d’une base de Schiff. According to one embodiment, the oxidized polysaccharide is crosslinked, for example by an amine and forming one of the constituents of a Schiff base.
Typiquement, le polysaccharide est soluble dans l’eau et comprend des fonctions aldéhydes réagissant au moins en partie avec un agent de réticulation formant ainsi ladite base de Schiff ou le produit de réaction avec un agent d’origine phénolique ou polyphénoliques. Typically, the polysaccharide is soluble in water and comprises aldehyde functions reacting at least in part with a crosslinking agent thus forming said Schiff's base or the reaction product with an agent of phenolic or polyphenolic origin.
Selon l’invention, on préfère des solutions de polysaccharide oxydé présentant un temps de prise de moins de 5 minutes à 100°C. According to the invention, preferred are solutions of oxidized polysaccharide having a setting time of less than 5 minutes at 100 ° C.
De préférence lorsque l’agent de réticulation est une diamine, qui possède en général un pKa élevé, leur intégration dans l’eau à des concentrations très élevées rend le milieu très basique (pH 10-12). Dans ces conditions, la réaction est immédiate, peu importe la température. A l’inverse, dans des conditions de pH acide (pH<5), la réaction n’a pas lieu, peu importe la température. De fait, l’utilisation de diamines pour la prise thermique du polysaccharide oxydé, et en particulier de la cellulose oxydée, est pour l’instant limitée par la dépendance au pH de cette réaction. Selon une variante, on ajoute à la solution comprenant la diamine au moins un agent qui alcalinise le milieu lors d’une montée en température. Preferably when the crosslinking agent is a diamine, which generally has a high pKa, their integration into water at very high concentrations makes the medium very basic (pH 10-12). Under these conditions, the reaction is immediate, regardless of the temperature. Conversely, under conditions of acidic pH (pH <5), the reaction does not take place, regardless of the temperature. In fact, the use of diamines for the thermal uptake of the oxidized polysaccharide, and in particular of oxidized cellulose, is for the moment limited by the dependence on the pH of this reaction. According to a variant, one adds to the solution comprising the diamine at least one agent which alkalinizes the medium during a rise in temperature.
Selon un mode de réalisation, une composition adhésive selon l’invention comprend de 0,5 à 25 %m, typiquement de 10 à 20 %m d’agent réticulant. L’invention concerne aussi l’utilisation d’une composition selon l’invention ou susceptible d’être obtenue selon un procédé tel que défini selon l’invention comme une colle sèche. According to one embodiment, an adhesive composition according to the invention comprises 0.5 to 25% m, typically 10 to 20% m of crosslinking agent. The invention also relates to the use of a composition according to the invention or capable of being obtained according to a process as defined according to the invention, such as a dry glue.
L’invention concerne aussi l’utilisation d’une composition selon l’invention ou susceptible d’être obtenue selon un procédé tel que défini selon l’invention comme colle aqueuse. The invention also relates to the use of a composition according to the invention or capable of being obtained according to a process as defined according to the invention as an aqueous adhesive.
Le pouvoir collant de cette composition adhésive qui dépend de très nombreux facteurs (viscosité, teneur en matière sèche, mouillabilité des fibres, réactivité de la formulation...) est estimé d’après les mesures mécaniques de contrainte à la rupture selon la norme NF EN 319 faites sur des échantillons prototypes de laboratoire ou de cohésion interne faites sur des échantillons prototypes industriels et comparés à une formulation urée-formol standard. The tackiness of this adhesive composition, which depends on a large number of factors (viscosity, dry matter content, wettability of the fibers, reactivity of the formulation, etc.) is estimated from the mechanical measurements of stress at break according to the NF standard. EN 319 made on prototype laboratory or internal cohesion samples made on industrial prototype samples and compared to a standard urea-formalin formulation.
Selon un aspect, l’invention présente l’avantage de fournir une composition présentant une haute teneur en matière sèche. In one aspect, the invention has the advantage of providing a composition having a high dry matter content.
Selon un aspect, l’invention présente l’avantage de fournir une composition solide, sous forme de poudre, qui peut être par exemple remise en suspension, typiquement juste avant utilisation. En outre, la mise à disposition d’une résine sèche (poudre), dispersible dans l’eau avant utilisation, participe à l’optimisation et rationalisation du transport des matières premières. According to one aspect, the invention has the advantage of providing a solid composition, in powder form, which can for example be resuspended, typically just before use. In addition, the provision of a dry resin (powder), dispersible in water before use, contributes to the optimization and rationalization of the transport of raw materials.
Selon un aspect, l’adhésif colle des particules de bois, de préférence pour former un panneau de particules de bois. In one aspect, the adhesive bonds particles of wood, preferably to form a panel of wood particles.
Avantageusement, les compositions adhésives selon l’invention sont utilisables telles quelles en lieu et place des colles à bases aqueuses pétrosourcées de type aminoplastes, phénolplastes, à émulsion (vinyliques, polyuréthane) pour coller entre elles des particules ou des fibres. Advantageously, the adhesive compositions according to the invention can be used as such in place of adhesives based on petroleum-based aqueous bases of aminoplast, phenolplast, emulsion (vinyl, polyurethane) type in order to bond particles or fibers together.
L’invention concerne également un matériau, par exemple panneau de matériaux cellulosiques, typiquement du bois, et de préférence panneaux de particules de bois, comprenant des particules collées par au moins une composition selon l’invention ou susceptible d’être obtenue selon un procédé tel que défini selon l’invention. Avantageusement, le matériau comprenant des particules collées par au moins une composition adhésive selon l’invention comprend également de la mélamine, par exemple 1 à 10 %m, de préférence de 2 à 10 %m. The invention also relates to a material, for example panel of cellulosic materials, typically wood, and preferably panels of wood particles, comprising particles bonded with at least one composition according to the invention or capable of being obtained according to a process. as defined according to the invention. Advantageously, the material comprising particles bonded with at least one adhesive composition according to the invention also comprises melamine, for example 1 to 10% m, preferably 2 to 10% m.
L’invention concerne aussi un procédé de fabrication de panneaux de particules de matériau cellulosique, typiquement du bois. The invention also relates to a process for manufacturing particle boards of cellulosic material, typically wood.
En particulier, la fabrication de tels panneaux comprend la fourniture de particules de matériau cellulosique, typiquement du bois, non collées, et l’application d’une composition adhésive selon l’invention sur le matériau pour encoller les particules de matériau cellulosique et former ainsi un panneau encollé. In particular, the manufacture of such panels comprises the provision of particles of cellulosic material, typically wood, not glued, and the application of an adhesive composition according to the invention on the material to glue the particles of cellulosic material and thus form a glued panel.
Avantageusement le procédé comprend la conformation du panneau encollé et l’application d’une force de pressage et d’un chauffage sur panneau encollé. La force de pression et le chauffage dépendent en général de l’épaisseur du panneau, de la densité visée et des propriétés mécaniques désirées. Advantageously, the method comprises shaping the glued panel and the application of a pressing force and heating on the glued board. The pressing force and the heating are generally dependent on the thickness of the panel, the target density and the desired mechanical properties.
En général, un panneau comprend deux types de particules, à savoir des fines et des grosses particules (par exemple une proportion massique 1/3 fines et 2/3 grossières). Typiquement, par exemple, de grosses particules sont retenues par un tamis de 1 mm de maille alors que des particules fines passent à travers un tamis de 1 mm de maille, mais sans aucune limitation. Typiquement, les particules sont encollées séparément par batch, puis conformées avec, en général, d’abord la mise en place d’une couche de fines particules puis d’une couche de grosses particules et de nouveau d’une couche de fines particules, avec la couche de grosses particules en sandwich entre les couches de fines particules. In general, a panel comprises two types of particles, namely fine and coarse particles (eg 1/3 fine and 2/3 coarse mass ratio). Typically, for example, large particles are retained by a 1mm mesh screen while fine particles pass through a 1mm mesh screen, but without any limitation. Typically, the particles are glued separately by batch, then shaped with, in general, first the establishment of a layer of fine particles then a layer of large particles and again a layer of fine particles, with the coarse particle layer sandwiched between the fine particle layers.
Avantageusement, la cohésion interne est supérieure à 0,10 N/mm2, et de préférence supérieure à 0,20 N/mm2, et encore de préférence supérieure à 0,30 N/mm2. Advantageously, the internal cohesion is greater than 0.10 N / mm 2 , and preferably greater than 0.20 N / mm 2 , and more preferably greater than 0.30 N / mm 2 .
Avantageusement, l’invention permet la fabrication de panneaux à base de particules de matériau cellulosique, typiquement du bois, à faible impact environnemental et faible émissivité de COV, en tirant partie d’une ressource abondante et renouvelable, sans concurrence alimentaire. Advantageously, the invention allows the manufacture of panels based on particles of cellulosic material, typically wood, with low environmental impact and low VOC emissivity, by taking advantage of an abundant and renewable resource, without competition for food.
Avantageusement, l’invention permet à la composition adhésive d’atteindre le cahier des charges des colles aqueuses pétrosourcées existantes en termes de propriétés physico-chimiques. Advantageously, the invention allows the adhesive composition to meet the specifications of existing petroleum-based aqueous adhesives in terms of physicochemical properties.
Avantageusement, les matériaux de l’invention à base de particules collées selon l’invention, présentent un caractère beaucoup moins nocif que ceux fabriqués actuellement. Avantageusement, le matériau de l’invention est totalement fabriqué à partir de biomasse ou régénérable (NalC ), sans produits dérivés de l’industrie pétrochimique, ce qui présente un avantage écologique important. Advantageously, the materials of the invention based on particles bonded according to the invention exhibit a much less harmful nature than those currently manufactured. Advantageously, the material of the invention is completely made from biomass or regenerable (NalC), without products derived from the petrochemical industry, which presents an important ecological advantage.
Sur les figures : Figure 1 : Propriétés mécaniques (contrainte à la rupture) des prototypes laboratoire de panneaux de bois en fonction de la nature de la colle, de la nature et de la quantité d’additif (a) et du taux sec de colle (b). In the figures: Figure 1: Mechanical properties (tensile stress) of laboratory prototypes of wood panels as a function of the nature of the glue, the nature and quantity of additive (a) and the dry rate of glue (b).
Figure 2 : Propriétés mécaniques (cohésion interne) des prototypes industriels de panneaux de bois en fonction de la nature de la colle, de la quantité d’additif et du taux sec dé collé. Figure 2: Mechanical properties (internal cohesion) of industrial prototypes of wood panels depending on the nature of the glue, the amount of additive and the dry rate of glue.
Figure 3 : Résistance à l’eau des prototypes laboratoire de panneaux de bois en fonction du taux de mélamine dans la colle de cellulose oxydée. Figure 3: Water resistance of laboratory prototypes of wood panels as a function of the level of melamine in the oxidized cellulose glue.
D'autres buts, caractéristiques et avantages de l'invention apparaîtront clairement à l'homme de l'art suite à la lecture de la description explicative qui fait référence à des exemples qui sont donnés seulement à titre d'illustration et qui ne sauraient en aucune façon limiter la portée de l'invention. Other objects, characteristics and advantages of the invention will become clear to those skilled in the art upon reading the explanatory description which refers to examples which are given only by way of illustration and which cannot be taken into account. in no way limit the scope of the invention.
Les exemples font partie intégrante de la présente invention et toute caractéristique apparaissant nouvelle par rapport à un état de la technique antérieure quelconque à partir de la description prise dans son ensemble, incluant les exemples, fait partie intégrante de l'invention dans sa fonction et dans sa généralité. The examples form an integral part of the present invention and any feature which appears new with respect to any state of the prior art from the description taken as a whole, including the examples, forms an integral part of the invention in its function and in its generality.
Ainsi, chaque exemple a une portée générale. Thus, each example has a general scope.
D'autre part, dans les exemples, tous les pourcentages sont des pourcentages massiques (sauf indication contraire), la température est exprimée en degré Celsius (sauf indication contraire), et la pression est la pression atmosphérique (sauf indication contraire). On the other hand, in the examples, all the percentages are mass percentages (unless otherwise indicated), the temperature is expressed in degrees Celsius (unless otherwise indicated), and the pressure is atmospheric pressure (unless otherwise indicated).
Les pourcentages d’oxydation de polysaccharide indiqués dans les exemples sont évalués par le dosage par formation d’oxime. The polysaccharide oxidation percentages indicated in the examples are evaluated by the oxime formation assay.
EXEMPLES EXAMPLES
Exemple 1 - Oxydation de cellulose Example 1 - Oxidation of cellulose
On procède à l’oxydation de la cellulose par le périodate de sodium selon le protocole suivant : The cellulose is oxidized with sodium periodate according to the following protocol:
150 g de pâte à papier (cellulose sulfite de résineux de la société DOMSJO), au préalable homogénéisés dans l’eau via robot mélangeur, et 250 g de périodate de sodium (Nal04) sont introduits dans 5 L d’eau pour 72 h sous agitation mécanique à pH libre (pH non tamponné). 150 g of paper pulp (resinous cellulose sulphite from the company DOMSJO), previously homogenized in water via a mixing robot, and 250 g of sodium periodate (Nal0 4 ) are introduced into 5 L of water for 72 h with mechanical stirring at free pH (unbuffered pH).
La cellulose oxydée est ensuite rincée par filtration ou centrifugation. The oxidized cellulose is then rinsed by filtration or centrifugation.
A ce stade, la cellulose oxydée est en suspension instable dans l’eau. At this point, the oxidized cellulose is in an unstable suspension in water.
Exemple 2 - Fluidification par traitement pH Example 2 - Fluidification by pH treatment
La cellulose oxydée obtenue selon l’exemple 1 est portée à pH 9 (réglé par ajout de NaOH) pendant 1 h 30 sous agitation mécanique à température ambiante. Une fois le procédé terminé, le milieu est ramené à pH 4-5 par ajout d’HCI. The oxidized cellulose obtained according to Example 1 is brought to pH 9 (adjusted by adding NaOH) for 1 hour 30 minutes with mechanical stirring at room temperature. Once the process is complete, the medium is brought to pH 4-5 by adding HCl.
Le milieu, initialement blanc et opaque, devient de plus en plus translucide et légèrement jaunâtre au fur et à mesure que la cellulose oxydée se solubilise. Il peut être nécessaire d’utiliser un disperseur cylindrique de type Ultra-T urrax pour casser les agrégats résistants. L’étape de formulation se termine quand la cellulose oxydée a disparu et que la solution obtenue est homogène. The medium, initially white and opaque, becomes more and more translucent and slightly yellowish as the oxidized cellulose dissolves. It may be necessary to use an Ultra-T urrax cylindrical disperser to break up tough aggregates. The formulation step ends when the oxidized cellulose has disappeared and the solution obtained is homogeneous.
Exemple 3 - Fluidification par chauffage Example 3 - Fluidification by heating
La cellulose oxydée obtenue selon l’exemple 1 est chauffée à 80 °C dans un montage à reflux sous agitation mécanique pendant 15 h. The oxidized cellulose obtained according to Example 1 is heated to 80 ° C in a reflux assembly with mechanical stirring for 15 h.
Les mêmes modifications d’état que lors d’un traitement pH sont observées. The same state changes as during a pH treatment are observed.
Exemple 4 - Ajustement par voie liquide Example 4 - Liquid adjustment
En voie liquide, il est possible de concentrer une solution obtenue en fin d’exemple 2 ou d’exemple 3 (taux de matière sèche d’environ 15 %m) en utilisant un évaporateur rotatif. On procède à l’évaporation jusqu’à l’obtention d’un taux de matière sèche d’environ 50 %m. Exemple 5 - Ajustement par voie sèche In the liquid process, it is possible to concentrate a solution obtained at the end of Example 2 or of Example 3 (dry matter content of about 15% m) using a rotary evaporator. Evaporation is carried out until a dry matter content of about 50% m is obtained. Example 5 - Dry adjustment
En voie sèche, il est possible de concentrer une solution obtenue en fin d’exemple 2 ou d’exemple 3 (matière sèche d’environ 15 %m) en lyophilisant la cellulose oxydée et obtenir une poudre sèche. Il est possible de remettre la composition lyophilisée en milieu aqueux à la matière sèche désirée, typiquement d’environ 50 %m. In the dry process, it is possible to concentrate a solution obtained at the end of Example 2 or of Example 3 (dry matter of about 15% m) by lyophilizing the oxidized cellulose and obtaining a dry powder. It is possible to return the lyophilized composition in aqueous medium to the desired dry matter, typically of about 50% m.
Le rendement de matière de toutes ces étapes de formulation (exemples 1 , 2 ou 3 et 4 ou 5) est situé autour de 75 %m (masse de cellulose oxydée finale rapportée à la masse de cellulose initialement introduite). Le rendement d’oxydation de la cellulose est d’environ 90 %m (pour les 75 %m de matière final). The yield of material from all of these formulation steps (Examples 1, 2 or 3 and 4 or 5) is around 75% m (weight of final oxidized cellulose relative to the weight of cellulose initially introduced). The oxidation yield of cellulose is approximately 90% m (for the 75% m of final material).
Exemple 6 - Prise d’une composition adhésive Example 6 - Taking an adhesive composition
On fait réticuler une composition obtenue selon l’exemple 5 : A composition obtained according to Example 5 is crosslinked:
6.1 On mélange à température ambiante 4 ou 8 g de colle à 15 %m en présence de 435 mg d’hexaméthylène diamine. Le ratio aldéhyde/amine est donc de 1/1 ou 2/1 respectivement, en considérant un pourcentage d’oxydation de 100 %. 6.1 4 or 8 g of 15% m glue are mixed at room temperature in the presence of 435 mg of hexamethylene diamine. The aldehyde / amine ratio is therefore 1/1 or 2/1 respectively, considering an oxidation percentage of 100%.
Résultat : apparition immédiate d’un précipité dans les deux cas. Result: immediate appearance of a precipitate in both cases.
6.2 On mélange 3 g de colle à 15 %m avec de la mélamine dans des proportions molaires {cellulose oxydée/mélamine} de 9/1 dans un tube à essai. On agite manuellement jusqu’à homogénéisation du mélange. Le tube à essai est mis au bain-marie dans l’eau bouillante jusqu’à réticulation. Le temps de gel est chronométré. La prise en masse est vérifié via l’introduction d’une pipette Pasteur dans le tube à essai contenant le mélange. 6.2 3 g of 15% m glue are mixed with melamine in molar proportions {oxidized cellulose / melamine} of 9/1 in a test tube. Stir manually until the mixture is homogenized. The test tube is placed in a water bath in boiling water until crosslinking. The freezing time is timed. The solidification is checked by inserting a Pasteur pipette into the test tube containing the mixture.
Résultat : Result:
• Temps de gel pour le ratio 9:1 : 4 min 05 s. Reproductible. • Freeze time for the 9: 1 ratio: 4 min 05 s. Reproducible.
On peut ainsi réaliser une prise chimique par réticulation à température ambiante (20 °C) en présence de diamine et une prise chimique par réticulation par chauffage en présence de mélamine. It is thus possible to achieve a chemical setting by crosslinking at room temperature (20 ° C.) in the presence of diamine and a chemical setting by crosslinking by heating in the presence of melamine.
Exemple 7 - Fabrication de panneaux de particules de bois Example 7 - Manufacture of particleboard panels
Des prototypes de panneaux de particules de bois ont été fabriqués à partir de colle de cellulose et de particules fournies par une unité industrielle. Ils ont été produits en 3 couches à l’échelle laboratoire et pilote-industrielle (Tableau 1). Les résines ont été déposées en 5 min sous formes de gouttes atomisées à la surface des particules à l’aide d’un mélangeur à pales avec un axe tournant à 100 tr.min_1. L’encollage des éléments fins (longueur<0,5 mm en moyenne) a été réalisé séparément des éléments plus grossiers (longueur > 0,5 mm en moyenne). Dans un moule spécifique rectangulaire de dimension 32x32 cm2 ou 55x55 cm2 des couches successives de particules ont été déposées en suivant l’ordre et les proportions massiques suivantes : 1/6 éléments fins, 2/3 éléments plus grossier, 1/6 éléments fins. Le matelas de particules a été introduit dans une presse à plateaux chauffés à 200 °C pendant au moins 300 s. Les panneaux ont été réalisés dans les même conditions à partir de colles aminoplastes conventionnelles qui servent de référence et celles décrites dans le document. Prototypes of wood particle boards were made from cellulose and particle glue supplied by an industrial unit. They were produced in 3 layers at laboratory and pilot-industrial scale (Table 1). The resins were deposited 5 minutes in the form of atomized drops on the particle surface using a paddle mixer with a rotating shaft at 100 r _1. The gluing of the thin elements (length <0.5 mm on average) was carried out separately from the coarser elements (length> 0.5 mm on average). In a specific rectangular mold measuring 32x32 cm 2 or 55x55 cm 2, successive layers of particles were deposited in the following order and the following mass proportions: 1/6 fine elements, 2/3 coarser elements, 1/6 elements purposes. The particle mat was introduced into a press with platens heated to 200 ° C for at least 300 s. The panels were produced under the same conditions from conventional aminoplast glues which serve as a reference and those described in the document.
Les matériaux obtenus ont été caractérisés et leurs propriétés ont été comparées à des panneaux de bois références fabriquées selon le même procédé à partir de colles commercialisées et aux données issues de la littérature. Les tests effectués sur les prototypes industriels ont été sélectionnés d’après les normes répandues dans le domaine des panneaux de bois (EN317 et EN 319).
Figure imgf000017_0001
The materials obtained were characterized and their properties were compared with reference wood panels manufactured using the same process from marketed adhesives and with data from the literature. The tests carried out on industrial prototypes were selected according to the standards widely used in the field of wood panels (EN317 and EN 319).
Figure imgf000017_0001
Tableau 1 : Données des prototypes de panneaux de bois fabriqués à partir de cellulose oxydée à l’échelle laboratoire et industrielle Table 1: Data of prototypes of wood panels made from oxidized cellulose at laboratory and industrial scale
La caractérisation de prototypes laboratoire montre que la colle de cellulose seule permet d’atteindre 60 % des propriétés des panneaux obtenus à partir d’une colle référence urée/formol à même taux sec de colle (Figure 1). L’ajout de mélamine dans la colle de cellulose oxydée permet d'augmenter les propriétés mécaniques des panneaux (cohésion interne EN319). Ces observations sont confirmées sur des panneaux obtenus par un procédé pilote (figure 2). The characterization of laboratory prototypes shows that cellulose glue alone achieves 60% of the properties of panels obtained from a urea / formalin reference glue at the same dry glue rate (Figure 1). The addition of melamine in the oxidized cellulose glue increases the mechanical properties of the panels (internal cohesion EN319). These observations are confirmed on panels obtained by a pilot process (figure 2).
La contrainte à la rupture atteint alors un maximum pour 4 %m (équivalent masse humide EN319) de mélamine. A ce pourcentage, les propriétés mécaniques sont équivalentes au système de référence. Les propriétés mécaniques augmentent également avec la quantité de colle sèche introduite dans le panneau. Cette évolution est très similaire entre panneaux à base d’urée/formol et à base cellulose oxydée/mélamine (4 %m). The breaking stress then reaches a maximum for 4% m (wet weight equivalent EN319) of melamine. At this percentage, the mechanical properties are equivalent to the reference system. The mechanical properties also increase with the amount of dry glue introduced into the panel. This development is very similar between urea / formalin-based and oxidized cellulose / melamine-based panels (4% m).
L’ajout de mélamine permet également d’augmenter la résistance à l’eau des échantillons (Figure 3) (EN317). Sans mélamine, la résistance à l’eau est médiocre, les prototypes se délitent complètement au bout d’une 1 heure dans l’eau bouillante. L’ajout de 1 %m de mélamine permet aux échantillons de conserver leur forme dans ces conditions même si les propriétés mécaniques sont fortement altérées. Au-delà de 1 %m, la résistance à l’eau augmente proportionnellement avec la quantité de mélamine. La mélamine permet également de limiter la dissolution de la colle de cellulose des panneaux de bois immergés à température ambiante pendant 24 h. Cette observation permet de renforcer l’hypothèse de création d’un réseau tridimensionnel. The addition of melamine also increases the water resistance of the samples (Figure 3) (EN317). Without melamine, the water resistance is poor, the prototypes completely disintegrate after 1 hour in boiling water. The addition of 1% m melamine allows the samples to retain their shape under these conditions even if the mechanical properties are severely impaired. Above 1% m, water resistance increases proportionally with the amount of melamine. Melamine also makes it possible to limit the dissolution of the cellulose glue of wooden panels immersed at room temperature for 24 hours. This observation reinforces the hypothesis of the creation of a three-dimensional network.

Claims

REVENDICATIONS
1. Composition adhésive sous forme de solution ou dispersion comprenant au moins un polysaccharide soluble ou dispersible dans l’eau comprenant des fonctions aldéhydes, ladite solution ou dispersion présentant une matière sèche supérieure à 20 %m, de préférence d’au moins 30 %m et encore de préférence d’au moins 40 %m, exprimé en pourcentage massique de matière sèche par rapport à la masse totale de la solution ou dispersion. 1. Adhesive composition in the form of a solution or dispersion comprising at least one polysaccharide soluble or dispersible in water comprising aldehyde functions, said solution or dispersion having a dry matter greater than 20% m, preferably at least 30% m and more preferably at least 40% m, expressed as a percentage by mass of dry matter relative to the total mass of the solution or dispersion.
2. Composition adhésive selon la revendication 1 , caractérisée en ce qu’elle est sous forme de solution transparente. 2. An adhesive composition according to claim 1, characterized in that it is in the form of a transparent solution.
3. Composition adhésive sous forme de poudre soluble dans l’eau comprenant au moins un polysaccharide soluble dans l’eau comprenant des fonctions aldéhydes, ladite composition sous forme poudre étant apte à présenter dans l’eau une quantité de matière sèche supérieure à 20 %m. 3. Adhesive composition in the form of a powder soluble in water comprising at least one polysaccharide soluble in water comprising aldehyde functions, said composition in powder form being able to present in water a quantity of dry matter greater than 20%. mr.
4. Composition comprenant au moins un polysaccharide oxydé réticulé, le polysaccharide avant réticulation étant soluble ou dispersible dans l’eau et comprenant des fonctions aldéhydes formant des liaisons covalentes réticulant ledit polysaccharide oxydé réticulé. 4. Composition comprising at least one oxidized cross-linked polysaccharide, the polysaccharide before cross-linking being soluble or dispersible in water and comprising aldehyde functions forming covalent bonds cross-linking said oxidized cross-linked polysaccharide.
5. Composition selon l’une quelconque des revendications précédentes caractérisée en ce que le polysaccharide est une cellulose, par exemple une cellulose microcristalline, une pâte à papier Kraft ou une pâte bisulfite. 5. Composition according to any one of the preceding claims, characterized in that the polysaccharide is a cellulose, for example a microcrystalline cellulose, a Kraft paper pulp or a bisulfite pulp.
6. Procédé de préparation d’une composition selon l’une quelconque des revendications précédentes, caractérisé en ce que le procédé comprend une réaction d’oxydation d’au moins un polysaccharide pour l’obtention d’au moins un polysaccharide oxydé comprenant des fonctions aldéhydes, ladite réaction d’oxydo-réduction étant par exemple réalisée par le périodate de sodium (NalC>4) (oxydant). 6. Process for preparing a composition according to any one of the preceding claims, characterized in that the process comprises an oxidation reaction of at least one polysaccharide to obtain at least one oxidized polysaccharide comprising functions. aldehydes, said oxidation-reduction reaction being for example carried out with sodium periodate (NalC> 4) (oxidant).
7. Procédé selon la revendication 6, caractérisé en ce que le polysaccharide comprend des unités anhydroglucose et en ce que la réaction d’oxydation conduit à la création de deux groupements aldéhydes aux carbones C2 et C3 des unités anhydroglucose. 7. Method according to claim 6, characterized in that the polysaccharide comprises anhydroglucose units and in that the oxidation reaction leads to the creation of two aldehyde groups at the C2 and C3 carbons of the anhydroglucose units.
8. Procédé selon la revendication 6 ou 7, caractérisé en ce qu’il comprend un rinçage, de préférence par filtration ou centrifugation, du polysaccharide oxydé. 8. Method according to claim 6 or 7, characterized in that it comprises rinsing, preferably by filtration or centrifugation, of the oxidized polysaccharide.
9. Procédé selon l’une quelconque des revendications 6 à 8, caractérisé en ce qu’il comprend une fluidification, de préférence par traitement à pH basique ou par chauffage, par exemple supérieur à 60 °C, et de préférence supérieur à 70 °C, par exemple à 80 °C sous reflux. 9. Method according to any one of claims 6 to 8, characterized in that it comprises fluidization, preferably by treatment at basic pH or by heating, for example greater than 60 ° C, and preferably greater than 70 ° C, for example at 80 ° C under reflux.
10. Procédé selon la revendication 9, caractérisé en ce qu’il comprend un ajustement augmentant la matière sèche de la solution ou dispersion obtenue après fluidification, par exemple par voie liquide, par exemple par évaporation partielle ou totale de milieu liquide, ou par voie sèche, par exemple par lyophilisation, puis éventuelle remise en solution aqueuse. 10. The method of claim 9, characterized in that it comprises an adjustment increasing the dry matter of the solution or dispersion obtained after fluidization, for example by liquid route, for example by partial or total evaporation of liquid medium, or by route. dries, for example by freeze-drying, then optionally putting back into aqueous solution.
11. Procédé selon la revendication 9, caractérisé en ce qu’il comprend un séchage pour l’obtention d’une composition adhésive sous forme de poudre selon la revendication 3. 11. The method of claim 9, characterized in that it comprises drying to obtain an adhesive composition in powder form according to claim 3.
12. Utilisation d’une composition selon l’une quelconque des revendications 1 à 5 ou susceptible d’être obtenue selon un procédé tel que défini selon l’une quelconque des revendications 6 à 11 comme adhésif. 12. Use of a composition according to any one of claims 1 to 5 or obtainable according to a process as defined in any one of claims 6 to 11 as an adhesive.
13. Utilisation selon la revendication 12, comme adhésif par prise physique, par exemple par l’évaporation du solvant, et de préférence sous forme d’une colle sans additif. 13. Use according to claim 12, as an adhesive by physical setting, for example by evaporation of the solvent, and preferably in the form of an adhesive without additives.
14. Utilisation selon la revendication 12, comme adhésif par prise chimique, par exemple par réticulation, par exemple avec un agent de réticulation soit d’origine phénolique ou polyphénoliques comme les acides-phénols, les flavones, les anthocyanes, les tanins ou les lignines, soit portant des fonctions amines formant ainsi ladite base de Schiff, de préférence l’agent de réticulation est choisi parmi la famille des polyamines par exemple une diamine ou la mélamine. 14. Use according to claim 12, as adhesive by chemical setting, for example by crosslinking, for example with a crosslinking agent either of phenolic or polyphenolic origin such as acid-phenols, flavones, anthocyanins, tannins or lignins. , or carrying amine functions thus forming said Schiff base, preferably the agent crosslinking is chosen from the family of polyamines, for example a diamine or melamine.
15. Utilisation selon l’une quelconque des revendications 12 à 14, caractérisée en ce que la composition est une colle sèche. 15. Use according to any one of claims 12 to 14, characterized in that the composition is a dry glue.
16. Utilisation selon l’une quelconque des revendications 12 à 14, caractérisée en ce que la composition est une colle aqueuse. 16. Use according to any one of claims 12 to 14, characterized in that the composition is an aqueous glue.
17. Utilisation selon l’une quelconque des revendications 12 à 16, caractérisée en ce que l’adhésif colle des particules de bois, de préférence pour former un panneau de particules de bois. 17. Use according to any one of claims 12 to 16, characterized in that the adhesive bonds wood particles, preferably to form a panel of wood particles.
18. Matériau, par exemple panneau de matériaux cellulosiques, typiquement du bois, et de préférence panneaux de particules de bois, comprenant des particules collées par au moins une composition selon l’une quelconque des revendications 1 à 5 ou susceptible d’être obtenue selon un procédé tel que défini selon l’une quelconque des revendications 6 à 11. 18. Material, for example panel of cellulosic materials, typically wood, and preferably panels of wood particles, comprising particles bonded by at least one composition according to any one of claims 1 to 5 or obtainable according to any one of claims 1 to 5. a method as defined according to any one of claims 6 to 11.
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