METHOD FOR THE PRODUCTION OF BIOLOGICALLY ORIGINAL POLYEPOXIDES WITH IMPROVED PROPERTIES

Description

technical field

[0001] This disclosure falls within the field of polyepoxides and relates in particular to a process for preparing epoxy prepolymers comprising glycidyl ethers of dianhydrohexitol motifs as well as glycidyl ethers of other alcohol motifs. Previous technique

[0002] Polyepoxides, also called epoxy polymers or commonly "epoxy", are widely used both as surface materials, for example for the manufacture of adhesives or coatings, and as structural materials, for example as a matrix for composite materials.

[0003] Polyepoxides are obtained by hardening curable compositions comprising epoxy prepolymers.

[0004] For the purposes of this invention, an epoxy prepolymer is a mixture of molecules comprising epoxide groups capable of undergoing further polymerization leading to the formation of a polyepoxide. Epoxy prepolymers may or may not include an oligomeric fraction. They may or may not include a polymeric fraction.

[0005] Most curable compositions comprising epoxy prepolymers used, in particular, for the manufacture of adhesives, coatings, or matrices for composite materials contain, in addition to epoxy prepolymers, at least one hardener and / or at least one accelerator.

[0006] During the curing of the curable composition containing epoxy prepolymers, chemical bonds are formed between molecules of the epoxy prepolymer and / or between the epoxy prepolymer and a hardener through opening reactions of the epoxy groups of the epoxy prepolymer. This results in the formation of a three-dimensional macromolecular network.

[0007] Accelerators are compounds that catalyze the homopolymerization reaction between two epoxide groups or the reaction between an epoxide group and the curing agent. Lewis acids, Lewis bases, and photoinitiators are examples.

[0008] A hardener is defined as any compound other than epoxy prepolymers that allows the formation of a three-dimensional network through reaction with the epoxy groups of said prepolymers. Examples include amines, amidoamines, Mannich bases, organic acids (including polyesters ending in carboxylic groups), organic acid anhydrides, and latent hardeners (such as cyanamide, imidazole, etc.).

[0009] In one-component curable compositions, the accelerators and / or hardeners are directly incorporated into the epoxy prepolymer composition: these are called 1K systems. In two-component curable compositions, the accelerating agent and / or the hardening agent is packaged separately from the epoxy prepolymer composition and the mixing only takes place at the time of application of the shaping of the curable composition: these are called 2K systems.

[0010] Curable compositions including epoxy prepolymers may also contain organic or inorganic fillers (silica, sand, aluminum oxide, talc, calcium carbonate, etc.), pigments, plasticizers, stabilizers, thixotropic agents.

[0011] Bisphenol A diglycidyl ether (BADGE or DGEBA), of formula (i), is a chemical compound now very widely used as an epoxy prepolymer.

[0012] DGEBA is a product obtained from petroleum, which is a disadvantage in a context of rising costs and / or scarcity of petroleum resources.

[0013] On the other hand, bisphenol A is now recognized as an endocrine disruptor.

[0014] This makes the handling of bisphenol A-based epoxy prepolymers or contact with polyepoxides obtained from DGEBA potentially hazardous to health.

[0015] It has been known for some years that DGEBA can be replaced by mixtures containing isosorbide diglycidyl ether, which is a bio-based product whose structure is shown below (formula (ii)).

[0016] This compound, which belongs to the broader class of dianhydrohexitol diglycidyl ethers, is now widely known and described in the literature, as is its synthetic process. For example, documents US3272845, US4770871, WO2008 / 147472, WO2008 / 147473, US3041300, WO2012 / 157832, and WO2015 / 110758 disclose synthetic processes for dianhydrohexitol diglycidyl ethers.

[0017] When any of the processes described in the documents cited above are implemented, the result is in fact a composition of epoxy prepolymers containing, in addition to dianhydrohexitol diglycidyl ether, dianhydrohexitol monoglycidyl ether as well as oligomers comprising dianhydrohexitol and glyceryl motifs. These oligomers may include one or more glycidyl ether groups carried by dianhydrohexitol and / or glyceryl motifs.

[0018] In this application, an epoxy prepolymer based on an alcohol is defined as an epoxy prepolymer in which the epoxy functions are essentially included in glycidyl ether groups and in which the glycidyl ether groups are essentially borne by motifs of said alcohol or glyceryl motifs which are themselves linked to motifs of said alcohol.

[0019] For example, in an isosorbide-based epoxy prepolymer, the glycidyl ether groups are primarily attached to isosorbide moieties and glyceryl moieties bonded to isosorbide moieties. The glycidyl ether groups thus appear, for example, as mono- or di-glycidyl ethers of isosorbide, or as glycidyl ether-isosorbide-... motifs in oligomers.

[0020] Thus, the epoxy prepolymer compositions obtained by implementing the processes described in the documents cited above are dianhydrohexitol-based or isosorbide-based epoxy prepolymers.

[0021] In this application, a polyepoxide obtained by hardening an epoxy prepolymer based on said alcohol is referred to as "alcohol-based polyepoxide".

[0022] The presence of monoglycidyl ether compounds and / or oligomers in addition to diglycidyl ether compounds in a diol-based epoxy prepolymer decreases the crosslinking density in the three-dimensional macromolecular network obtained by curing a curable composition comprising said epoxy prepolymer compared to what would be obtained if the curable composition comprised the diglycidyl ether of said pure diol as the epoxy prepolymer.

[0023] This crosslinking density is related to the glass transition temperature (Tg) of the polyepoxide. A high crosslinking density results in a material with a higher glass transition temperature (Tg) and greater chemical and mechanical resistance.

[0024] The presence of oligomers and / or mono-glycidyl ethers in an epoxy prepolymer can be directly related to the epoxy equivalent by weight (EEW), defined as the mass of epoxy prepolymer containing one equivalent of glycidyl ether groups. For example, pure isosorbide diglycidyl ether (formula ii), which has a molecular weight of 258 g / mol and contains 2 glycidyl ether groups, has an epoxy equivalent of 129 g / eq.

[0025] In a diol-based epoxy prepolymer, the EEW is minimal if the epoxy prepolymer is pure diglycidyl ether of the diol. The EEW of the epoxy prepolymer increases as the oligomer and / or monoglycidyl ether content of the diol increases in the epoxy prepolymer.

[0026] Polyepoxides were prepared from isosorbide diglycidyl ether-based epoxy prepolymers.

[0027] However, it remains difficult to obtain bio-based polyepoxides with performance equivalent to polyepoxides obtained from petroleum-based compounds such as DGEBA.

[0028] Document US2015 / 0353676 A1 describes, in particular, polyepoxides based on isosorbide and, as a hardener, on cis-4-cyclohexene-1,2-dicarboxylic acid.

[0029] Document US2018 / 0230261 A1 describes isosorbide-based polyepoxides and, as a hardener, a polyamide.

[0030] Document WO2015 / 110758 A1 describes polyepoxides based on isosorbide and, as a hardener, isophorone diamine. These polyepoxides have glass transition temperatures in the range of 95-100°C.

[0031] Similarly, documents US2017 / 0253692 and JP2014189713 describe isosorbide-based polyepoxides comprising various hardeners.

[0032] A recurring problem encountered so far with isosorbide-based polyepoxides is their significant water absorption; that is, water molecules readily diffuse into the three-dimensional macromolecular network of the polyepoxide. Thus, in the presence of humidity or liquid water, these polyepoxides tend to absorb water, which notably leads to plasticization (a decrease in their glass transition temperature), swelling, and a reduction in their cohesive and adhesive properties.

[0033] Significant water absorption is therefore incompatible with many applications of polyepoxides (adhesives, matrix for composite materials in particular), which is currently one of the main obstacles to the widespread use of dianhydrohexitol-based polyepoxides.

[0034] One solution to this problem, developed by the applicant company, consists of preparing polyepoxides from mixtures of dianhydrohexitol-based epoxy prepolymers and epoxy prepolymers based on other alcohols.

[0035] The objective is to combine the properties of dianhydrohexitol-based polyepoxides and the properties of polyepoxides based on other alcohols while compensating for their respective defects.

[0036] Continuing its research, the Applicant company discovered that if dianhydrohexitol and the other alcohol are mixed before the epoxy prepolymer synthesis step, the resulting polyepoxide exhibits better properties, particularly lower water absorption, than the polyepoxide obtained from mixing the epoxy prepolymers synthesized separately from dianhydrohexitol and the other alcohol. This surprising effect is the subject of the present invention. Summary

[0037] This disclosure relates to the preparation of epoxy prepolymers comprising dianhydrohexitol glycidyl ethers enabling the production of polyepoxides with improved water readjustment.

[0038] A process for preparing a composition of epoxy prepolymers comprising glycidyl ethers is thus proposed, said process comprising the following steps: a. Contact a dianhydrohexitol and another alcohol to obtain an alcohol composition; b. React the alcohol composition obtained in step a) with an epihalohydrin to obtain a reaction mixture comprising glycidyl ethers; c. Recover the epoxy prepolymer composition comprising glycidyl ethers from the reaction mixture obtained at the end of step b).

[0039] According to another aspect, a composition of epoxy prepolymers is proposed that can be obtained by the process according to the invention.

[0040] According to another aspect, a curable composition is proposed comprising a composition of epoxy prepolymers according to the invention, characterized in that it further comprises at least one accelerator and / or at least one hardener.

[0041] According to another aspect, a polyepoxide is proposed obtained by hardening a hardenable composition according to the invention.

[0042] According to another aspect, a composite material, a coating or an adhesive comprising a polyepoxide according to the invention is proposed.

[0043] Other features and advantages of the present invention will become apparent from the following detailed description. Detailed description

[0044] In this patent application, the expression "between ... and ..." should be understood as including the boundaries.

[0045] A process is proposed for preparing a composition of epoxy prepolymers comprising glycidyl ethers, said process comprising the following steps: a) Contact a dianhydrohexitol and another alcohol to obtain an alcohol composition; b) React the alcohol composition obtained in step a) with an epihalohydrin to obtain a reaction mixture comprising glycidyl ethers; c) Recover the epoxy prepolymer composition comprising glycidyl ethers from the reaction mixture obtained at the end of step b).

[0046] The first step of the process according to the invention (step a) therefore consists of bringing a dianhydrohexitol and another alcohol into contact.

[0047] Contact between dianhydrohexitol and the other alcohol can be achieved by mixing the two compounds, for example by dissolving dianhydrohexitol and the other alcohol or by melting dianhydrohexitol and the other alcohol in the case where they are miscible in the liquid state, or by mixing these compounds in the solid state, for example in powder form.

[0048] Dianhydrohexitols are heterocyclic compounds obtained by double dehydration of hexitols (such as iditol, mannitol, or sorbitol). They are therefore diols. Among the dianhydrohexitols, the isohexides correspond to 1,4:3,6-dianhydrohexitols and include isosorbide, isoidide, and isomannide.

[0049] In the process according to the invention, dianhydrohexitol is preferably an isohexitol, more preferably chosen from isosorbide, isomannide and isoidide, and is, most preferably, isosorbide.

[0050] In the process according to the invention, step b, the reaction with an epihalohydrin, allows the transformation of alcohol functions of dianhydrohexitol and the other alcohol into glycidyl ether groups. Oligomers can also be formed at this step. Among these oligomers, some comprise dianhydrohexitol motifs or motifs of another alcohol, and some comprise a mixture of dianhydrohexitol motifs and motifs of another alcohol.

[0051] The reaction mixture at the end of step b. therefore contains a composition of epoxy prepolymers comprising glycidyl ether groups carried by dianhydrohexitol motifs and glycidyl ether groups carried by other alcohol motifs.

[0052] Mixing at least one dianhydrohexitol and at least one other alcohol in step a., i.e. prior to step b. of reaction with epihalohydrin results in an unexpected effect.

[0053] Indeed, the polyepoxides obtained by hardening curable compositions comprising epoxy prepolymer compositions obtained by the process according to the invention exhibit properties, for example water reabsorption properties, improved compared to the properties of polyepoxides obtained by hardening comparable curable compositions resulting from the mixture of an epoxy prepolymer based on dianhydrohexitol and an epoxy prepolymer based on the other alcohol.

[0054] Without wishing to limit the scope of the invention to any particular theory, it is possible to think that this unexpected improvement of the polyepoxide is linked to the presence of oligomers comprising both dianhydrohexitol motifs and other alcohol motifs in the composition of epoxy prepolymers obtained by the process of the invention.

[0055] In the process according to the present invention, the other alcohol brought into contact with a dianhydrohexitol in step a. is preferably not a dianhydrohexitol.

[0056] More preferably, the other alcohol brought into contact with a dianhydrohexitol in step a. is chosen from the following alcohols: Trimethylol ethane, Trimethylol propane, Spiroglycol, Tricyclodecanedimethanol, Glycerol, Hexan-1,6-diol, Cn aliphatic diols, where n ≥ 7, Cyclohexan-1,m-dimethanol, where m = 2, 3 or 4, Furan-p,q-dimethanol, where {p,q} = {1,4}, {1,3} or {2,3}, Thiophen-p,q-dimethanol, where {p,q} = {1,4}, {1,3} or {2,3}, Isoborneol Dodecanol, or Decanol.

[0057] According to one embodiment of the process according to the invention, the other alcohol comprises at least two alcohol functions.

[0058] If the other alcohol comprises only one alcohol functional group, it can only be incorporated at the end of the chain in oligomers comprising both dianhydrohexitol motifs and other alcohol motifs contained in the epoxy prepolymer composition obtained by the process of the invention. If the other alcohol comprises at least two alcohol functional groups, the epoxy prepolymer composition obtained by the process of the invention may comprise oligomers comprising ...-dianhydrohexitol-glyceryl-other alcohol-glyceryl-... motifs or ...-dianhydrohexitol-glyceryl-other alcohol-glycidyl motifs.

[0059] Advantageously, the other alcohol brought into contact with a dianhydrohexitol in step a. of the process according to the invention is chosen in such a way that a polyepoxide based on said other alcohol has a lower water reabsorption than that of a polyepoxide based on said dianhydrohexitol.

[0060] In other words, a polyepoxide obtained by a hardening process of an epoxy prepolymer composition obtained by an etherification process of the other alcohol with an epihalohydrin, preferably has a lower water reabsorption than the water reabsorption, measured according to the same method, of a polyepoxide obtained by the same hardening and etherification processes but replacing the other alcohol with dianhydrohexitol.

[0061] In the process according to the invention, the other alcohol is preferably 1,4-cyclohexanedimethanol (CHDM).

[0062] In the process according to the invention, the ratio r between the number of moles of dianhydrohexitol and the sum of the number of moles of the other alcohol and the number of moles of dianhydrohexitol (r = n dianhydrohexitol / (n dianhydrohexitol + n other alcohol )) is preferably between 0.05 and 0.95, more preferably between 0.1 and 0.9.

[0063] In the process according to the invention, epihalohydrin is preferably chosen from epibromohydrin, epifluorohydrin, epiiodohydrin and epichlorohydrin, and is, more preferably, epichlorohydrin.

[0064] In the process according to the invention, step b. of reaction with epihalohydrin allows the transformation of alcohol functions of dianhydrohexitol and of the other alcohol into glycidyl ether groups.

[0065] It can be carried out by any process known to those skilled in the art which allows the transformation of alcohol functions of dianhydrohexitol and the other alcohol into glycidyl ether groups, for example, the processes described in documents US3272845, US4770871, WO2008 / 147472, WO2008 / 147473, US3041300, WO2012 / 157832 and WO2015 / 110758, preferably the process described in document WO2015 / 110758.

[0066] Thus, in the process according to the invention, step b) of reacting the alcohol composition with epihalohydrin preferably comprises the following steps: b1) Bring the alcohol composition and the epihalohydrin into contact to obtain a reaction mixture; b2) Place the reaction mixture obtained in step b1) under vacuum to obtain a vacuum of between 100 mbar and 1000 mbar; b3) Heat the reaction mixture obtained in step b2), while maintaining said vacuum, to a temperature of between 50°C and 120°C to carry out a distillation of the epihalohydrin; b4) Add a basic reagent to the reaction mixture obtained in step b3) for a period of between 1h and 10h while maintaining the reaction mixture at said vacuum and temperature to carry out an azeotropic distillation of the water-epihalohydrin azeotrope.

[0067] Step b1), the contacting of the alcohol composition and the epihalohydrin, is carried out in any apparatus well known to those skilled in the art, allowing contact between chemical reagents and equipped with heating and stirring devices. A double-jacketed reactor may be an example. The apparatus in question must also be equipped with a device for creating a partial vacuum and a device for conducting azeotropic distillation, such as an inverted Dean-Stark apparatus with a condenser.

[0068] Epihalohydrin is preferentially introduced in excess relative to the hydroxyl groups of the alcohols present in the alcohol composition (including dianhydrohexitol and the other alcohol). Thus, for 1 mole of hydroxyl groups, between 1 and 5 moles of epihalohydrin will be preferentially introduced, and more preferably approximately 2.5 moles of epihalohydrin.

[0069] After this initial contact step (step b1), a partial vacuum is created in the device using a vacuum pump, with the corresponding pressure drop being between 100 mbar and 1000 mbar (step b2). This means that the pressure in the reactor is equal to the difference between atmospheric pressure (1013 mbar) and the pressure drop (between 100 mbar and 1000 mbar), i.e., a pressure in the reactor between 13 mbar and 913 mbar.

[0070] According to one embodiment, step b2 is carried out so as to obtain a depression between 300 and 900 mbar, in particular between 500 and 800 mbar.

[0071] During step b3), the mixture of the alcohol composition and the epihalohydrin is heated to a temperature between 50°C and 120°C.

[0072] Preferably, the setpoint temperature of the reactor heating element should be adjusted to be at least equal to the boiling point of the epihalohydrin used, in order to initiate the distillation of the epihalohydrin. The boiling point to be considered is the boiling point of the epihalohydrin at the pressure prevailing in the reactor.

[0073] During this first distillation phase, only the epihalohydrin is distilled. Furthermore, only a portion of the epihalohydrin is distilled. This distilled portion can, for example, be recovered using a reverse Dean-Stark apparatus and potentially reintroduced into the reaction mixture.

[0074] For example, epichlorohydrin has a boiling point of 116°C at atmospheric pressure, which is approximately 80°C when the pressure in the reactor is 275 mbar (corresponding to a pressure drop of 738 mbar). In practice, the reactor heating element's setpoint temperature should be set slightly higher (approximately 30°C higher) than the boiling point of the epichlorohydrin in question and for the applied pressure drop.

[0075] During step b4), a basic reagent is added to the alcohol composition / epihalohydrin mixture for a period of between 1 and 10 hours.

[0076] The amount of basic reagent is preferably the stoichiometric amount relative to the number of hydroxyl groups of the alcohols present in the alcohol composition. However, one can choose to use a slightly higher amount than this stoichiometric ratio.

[0077] The basic reagent is preferably chosen from lithium, potassium, calcium or sodium hydroxides, preferably in the form of an aqueous solution, and is, more preferably, an aqueous solution of sodium hydroxide.

[0078] The ratio of the number of moles of OH- introduced with the basic reagent to the number of moles of hydroxyl functions of the alcohols present in the alcohol composition is then preferably between 0.9 and 1.2.

[0079] Upon introduction of the basic reagent (step b4), water is formed by the reaction between the alcohol composition and the epihalohydrin. Additional water can also be introduced by adding the basic reagent as an aqueous solution. The distillation is then an azeotropic distillation, involving the water-epihalohydrin mixture. In other words, the water-epihalohydrin azeotrope is distilled. After settling the distilled azeotrope, the water is removed, and the epihalohydrin returns to the reaction mixture. In the case of an inverted Dean-Stark apparatus, the water constitutes the upper phase, which is removed, while the epihalohydrin, in the lower phase, is reintroduced into the reaction mixture.

[0080] Azeotropic distillation is preferably continued until all water has been removed. The reaction mixture is then heated for a period of 30 minutes to 1 hour after the addition of the basic reagent has been completed.

[0081] Preferably, a phase transfer catalyst is added during step b1). This makes it possible to significantly reduce the viscosity of the manufactured products, while maintaining a very high proportion of dianhydrohexitol diglycidyl ether relative to dianhydrohexitol monoglycidyl ether.

[0082] The phase transfer catalyst is preferably chosen from tetra-alkylammonium halides, sulfates or hydrogen sulfates and more preferably from tetrabutylammonium bromide or tetrabutylammonium iodide.

[0083] The amount of phase-transfer catalyst is preferably between 0.01 and 5%, more preferably between 0.1% and 2%, and even more preferably 1% by weight relative to the total weight represented by the sum of the masses of dianhydrohexitol and the other alcohol. This allows for a very significant reduction in the EEW of the resulting epoxy prepolymer composition.

[0084] Preferably, step c) includes a filtration step of the reaction medium obtained from step b) to obtain a filtrate comprising the epoxy prepolymer composition. This filtration step removes salts formed during the reaction between the epihalohydrin and the alcohol composition, such as sodium chloride in the case of epichlorohydrin. The salts separated by filtration are preferably washed again with epihalohydrin. The washing epihalohydrin combined with the first filtrate then constitutes the filtrate comprising the epoxy prepolymer composition.

[0085] The filtration step (including washing away the removed salts) is preferably followed by a filtrate concentration and / or filtrate purification step.

[0086] The concentration step can be used, for example, to remove unreacted epihalohydrin and / or washing epihalohydrin. It can be carried out, for example, by vacuum distillation, such as in a rotary vaporizer and / or a scraped film evaporator. During this concentration step, the crude product or the epoxy prepolymer composition is, for example, gradually heated to 140°C and the pressure is reduced to, for example, 1 mbar (corresponding to a vacuum of 1012 mbar).

[0087] The purification step can be carried out, for example, by distillation under reduced pressure (pressure <1 mbar corresponding to a vacuum >1012 mbar) and can be performed using a scraped-surface heat exchanger to separate oligomeric compounds from diglycidyl ether compounds of dianhydrohexitol or the other alcohol. This step is distinct from the one described in the preceding paragraph.

[0088] According to another aspect of the present invention, a composition of epoxy prepolymers is proposed that can be obtained by the process according to the invention.

[0089] The epoxy prepolymer compositions that can be obtained by the process according to the invention have the advantage of having a reduced viscosity compared to dianhydrohexitol-based epoxy prepolymers obtained by the same process but without adding another alcohol to dianhydrohexitol.

[0090] Advantageously, the epoxy prepolymer compositions that can be obtained by the process according to the invention have a Brookfield viscosity, measured at 25°C, of ​​less than 4000 mPa.s, preferably less than 1000 mPa.s, without requiring a purification step by separating the oligomeric compounds from the diglycidyl ether compounds.

[0091] Low viscosity facilitates the shaping and processability of epoxy prepolymers. For example, the manufacturing of composite materials containing a polyepoxide matrix by casting, coating, infusion, impregnation, lamination, injection, pultrusion, or filament winding is made easier. Low viscosity also facilitates, for example, the deposition of thin films and the use of spray guns and rollers when applying polyepoxides as coatings or adhesives.

[0092] Viscosity is measured using a Brookfield DV-II+ rotary viscometer. The measurement is performed after stabilizing the medium at 25°C using a thermostatically controlled water bath. Viscosity measurements are obtained with a torque (expressed as a percentage of the viscometer's maximum torque) between 10% and 100%.

[0093] Throughout this Application, the speed at which the Brookfield viscosity is determined is not specified. Those skilled in the art know how to adjust it according to the choice of rotor and to achieve a percentage of the viscometer's maximum torque between 10 and 100%.

[0094] Once prepared, the epoxy prepolymer composition according to the invention can be crosslinked to form a hardened polyepoxide. It may be preferable to add a hardener and / or an accelerator to initiate or accelerate the crosslinking.

[0095] According to another aspect of the present invention, a curable composition is proposed comprising a composition of epoxy prepolymers according to the invention, characterized in that it further comprises at least one accelerator and / or at least one hardener.

[0096] A "curable composition" is defined as a liquid mixture capable of polymerizing to form a cross-linked (cured) resin. For example, a curable composition containing epoxy prepolymers is a liquid mixture capable of polymerizing to form a polyepoxide, which is by definition a cross-linked resin.

[0097] Preferably, the curable composition includes an amine-type hardener

[0098] The amine-type hardener can, for example, be chosen from: linear aliphatic diamines, in particular 1,2-diaminomethane, 1,3-diaminopropane, butane-1,4-diamine, pentane-1,5-diamine, 1,6-diaminohexane, or 1,12-diaminododecane; cyclic aliphatic diamines, in particular isophorone diamine (IPDA), 4,4'-diaminodicyclohexylmethane (PACM), 1,2-diaminocyclohexane (DACH), menthanediamine, or 1,3-bis(aminomethyl)cyclohexane (1,3 BAC); aromatic diamines, in particular 4,4'-methylenebis(2-aminophenyl)fluorene (BAFL), diethyltoluene diamine (DETDA), dimethylaminophenyl)fluorene (BAFL), diethyltoluene diamine (DETDA), dimethyl thiotoluene diamine (DMTDA), 4,4'-methylenebis(2-ethylaniline) (MOEA), m-xylenediamine, m-phenylenediamine (MPDA), or 4,4'-diaminodiphenylmethane, triamines, in particular diethylenateramine (DTA), tetramines, in particular triethylenetetramine, pentamines, in particular tetraethylenepentamine,dimeric fatty acid diamines, in particular Croda's Priamine®< 1074, polyetheramines, in particular poly(oxypropylene)diamine (Jeffamine®< D-230 from Huntsman Petrochemical, LLC), or poly(oxypropylene)triamine (Jeffamine®< T-403 from Huntsman Petrochemical, LLC), or any other polyamine, in particular polyethylene imine (e.g., BASF's Lupasol®< FG), dipropenediamine, diethylaminopropylamine, N-aminoethylpiperazine, dicyandiamide (Dicy), or a mixture thereof.

[0099] Preferably, the hardener is isophorone diamine.

[0100] The epoxy / amine system formed by the curable composition according to the invention can be stoichiometric or contain an excess of amine functions or an excess of epoxy functions.

[0101] The ratio of the number of NH bonds in the hardener formula (D) to the number of epoxy groups in the epoxy prepolymer composition can thus be between 1:2 and 2:1, in particular between 2:3 and 3:2, more particularly be equal to 1:1 (stoichiometric mixture).

[0102] For example, a primary amine function comprises two NH bonds. Thus, there will be 4 NH bonds per molecule of diamine isophorone.

[0103] Preferably, in the hardenable composition according to the invention, the accelerator is chosen from Lewis acids, tertiary amines or imidazole and its derivatives.

[0104] According to one embodiment, in the curable composition according to the invention, the accelerators and / or hardeners are directly incorporated into the epoxy prepolymer composition. The curable composition according to the invention is then of the single-component type (1K system).

[0105] According to one embodiment, in the curable composition according to the invention, the accelerators and / or hardeners are packaged separately from the epoxy prepolymer composition. The curable composition according to the invention is then of the two-component type (2K system).

[0106] According to another aspect of the present invention, a polyepoxide is proposed obtained by hardening the hardenable composition according to the invention.

[0107] The hardening (i.e., crosslinking) of the hardenable composition according to the invention can occur spontaneously or may require heating or irradiation by UV radiation.

[0108] In particular, the hardenable composition according to the invention can be crosslinked at a temperature between 5°C and 260°C.

[0109] More specifically, the hardenable composition according to the invention can be subjected to a curing cycle optionally comprising a period at room temperature followed by one or more heating periods at increasing temperatures between 30°C and 260°C. For example, the hardenable composition according to the invention can be subjected to a curing cycle of 1 hour at 80°C followed by 2 hours at 180°C.

[0110] Preferably, the polyepoxide according to the invention has a glass transition temperature (Tg) greater than or equal to 70°C, in particular between 70°C and 210°C, more particularly between 90°C and 200°C.

[0111] The glass transition temperature of the polyepoxide according to the invention can be determined by techniques known to those skilled in the art, in particular by differential scanning calorimetry (DSC), for example by means of a DSC Q20 apparatus in an open crucible with a Heat / Cool / Heat cycle from 0°C to 200°C at 10°C / min, or by dynamic mechanical analysis (DMA), for example by means of an Anton Paar MCR 501 Rheometer apparatus equipped with torsion jaws at a regulated temperature from 25°C to 250°C at 5°C / min and a frequency of 1Hz.

[0112] Furthermore, the polyepoxide according to the invention has a water absorption of less than or equal to 15%, in particular between 0.1% and 11%, more particularly between 0.5% and 9.5%, preferably between 1% and 9%, more particularly between 1.5% and 8.5%, even more particularly between 2% and 8%.

[0113] The water absorption of polyepoxide is determined by measuring the mass of a sample before and after water saturation obtained by immersion in water at room temperature for a sufficient time. For example, the water absorption of polyepoxide can be determined on parallelepiped samples measuring 50 mm x 25 mm x 2 mm immersed for 96 hours in water at room temperature, according to the following formula: reprise en eau % = masse après immersion − masse sèche masse sèche

[0114] According to another aspect of the present invention, a composite material, coating or adhesive comprising the polyepoxide according to the invention is proposed.

[0115] The composite materials according to the invention can be polyepoxide / fiber type composite materials, the fibers of which can be chosen in particular from glass fibers, carbon fibers, basalt fibers, plant fibers (flax, hemp).

[0116] The composite materials according to the invention can be useful for the production of high-performance structural parts, such as for example in the automotive, nautical, aeronautical or sports and leisure sectors. Examples

[0117] Water reabsorption of samples is determined on parallelepiped samples of 50 mm x 25 mm x 2 mm immersed for 96h in water at ambient temperature, according to the following formula: reprise en eau % = masse après immersion − masse sèche masse sèche

[0118] Glass transition temperatures (Tg) are determined by differential scanning calorimetry (DSC) under the following conditions: Apparatus: DSC Q20. Between 10 and 20 mg of product are deposited in an open crucible. A Heat / Cool / Heat cycle is performed from 0°C to 200°C at 10°C / min.

[0119] Viscosity is measured using a Brookfield DV-II+ rotary viscometer. The measurement is performed after stabilizing the medium at 25°C using a thermostatically controlled water bath. Viscosity measurements are obtained with a torque (expressed as a percentage of the viscometer's maximum torque) between 10% and 100%.

[0120] Epoxy equivalent by weight (EEW) is measured according to ISO 3001 or ASTM D1652. Example 1 : isosorbide 100% (comparative example)

[0121] In a 2.5 L double-jacketed reactor equipped with a stirring paddle and an inverted Dean-Stark condenser, 200 g of isosorbide, 633 g of epichlorohydrin (5 mol equivalents relative to the diol), and 2 g of tetraethylammonium bromide (TEAB, 1 wt% relative to the diol) are introduced. The reaction mixture is heated (set temperature: 110°C) under a partial vacuum of 275 mbar, maintained by a rotary vane pump (corresponding to a pressure drop of 1013 - 275 = 738 mbar). After distilling a sufficient quantity of epichlorohydrin to fill the inverted Dean-Stark condenser, 230 g of a 50 wt% aqueous sodium hydroxide solution are introduced using a peristaltic pump over a period of 3 hours. When sodium hydroxide is added, distillation of the water-epichlorohydrin azeotrope and demixing in the Dean-Stark allows the water introduced and formed during the reaction to be removed.Once the sodium hydroxide has been added, the mixture is heated and distilled until it reaches a temperature of 90°C. At this temperature, the heating is stopped and the mixture is allowed to cool to room temperature. The mixture is then removed from its container, and the salts formed during the reaction are filtered through a sintered glass filter with a porosity of 3. The salt cake is then washed with 150 g of acetone. The filtrate is collected. The washing solvents and residual epichlorohydrin are removed by vacuum distillation using a rotary evaporator. This yields 338 g of a homogeneous, yellow, viscous oil. The results of the analyses performed on the resulting epoxy prepolymer are presented in Table 1. [Table 1] Example 1 Example 2 Example 3 EEW (g / eq.) 189 164 169 Isosorbide conversion rate 100% 99.3% 99.6% CHDM conversion rate - 91.1% 79.6% Viscosity (mPa.s) 4360 175 990 Water content (g / 100g) 0.15 0.02 0.05 Example 2 : isosorbide 25% / CHDM 75% (example according to the invention)

[0122] In a 500 mL double-jacketed reactor equipped with a stirring paddle and an inverted Dean-Stark condenser, 10 g of isosorbide, 29.3 g of CHDM, 126 g of epichlorohydrin (5 mol equivalents relative to the diol), and 400 mg of tetraethylammonium bromide (TEAB, 1 wt% relative to the diol) are introduced. The reaction mixture is heated (set temperature: 110°C) under a partial vacuum of 275 mbar, maintained by a rotary vane pump (corresponding to a pressure drop of 1013 - 275 = 738 mbar). After distilling a sufficient quantity of epichlorohydrin to fill the inverted Dean-Stark flask, 45 g of a 50% (w / w) aqueous sodium hydroxide solution is introduced using a peristaltic pump over a period of 3 hours. Upon the addition of sodium hydroxide, the distillation of the water-epichlorohydrin azeotrope and the subsequent separation in the Dean-Stark flask allow the removal of the water introduced and formed during the reaction.Once the sodium hydroxide has been added, the mixture is heated and distilled until it reaches a temperature of 90°C. At this temperature, the heating is stopped and the mixture is allowed to cool to room temperature. The mixture is then removed from its container, and the salts formed during the reaction are filtered through a sintered glass filter with a porosity of 3. The salt cake is then washed with 50 g of acetone. The filtrate is collected. The washing solvents and residual epichlorohydrin are removed by vacuum distillation using a rotary evaporator. This yields 67 g of a homogeneous, yellow, viscous oil. The results of the analyses performed on the resulting epoxy prepolymer are presented in Table 1. Example 3 : isosorbide 75% / CHDM 25% (example according to the invention)

[0123] In a 2.5 L double-jacketed reactor equipped with a stirring paddle and an inverted Dean-Stark condenser, 174.6 g of isosorbide, 58.2 g of CHDM, 644 g of epichlorohydrin (5 mol equivalents relative to the diol), and 2.32 g of tetraethylammonium bromide (TEAB, 1 wt% relative to the diol) are introduced. The reaction mixture is heated (set temperature: 110°C) under a partial vacuum maintained by a vane pump of 275 mbar (corresponding to a pressure drop of 1013 - 275 = 738 mbar). After distilling a sufficient quantity of epichlorohydrin to fill the inverted Dean-Stark flask, 235 g of a 50% (w / w) aqueous sodium hydroxide solution is introduced using a peristaltic pump over a period of 3 hours. During this addition, the distillation of the water-epichlorohydrin azeotrope and the subsequent separation in the Dean-Stark flask allow the water introduced and formed during the reaction to be removed.Once the sodium hydroxide has been added, the mixture is heated and distilled until it reaches a temperature of 90°C. At this temperature, the heating is stopped and the mixture is allowed to cool to room temperature. The mixture is then removed from its container, and the salts formed during the reaction are filtered through a sintered glass filter with a porosity of 3. The salt cake is then washed with 150 g of acetone. The filtrate is collected. The washing solvents and residual epichlorohydrin are removed by vacuum distillation using a rotary evaporator. This yields 352 g of a homogeneous, yellow, viscous oil. The results of the analyses performed on the resulting epoxy prepolymer are presented in Table 1.

[0124] The products from examples 2 and 3 (respectively isosorbide 25% / CHDM 75% and isosorbide 75% / CHDM 25%) were crosslinked with isophorone diamine (IPDA). Thus

[0125] Example 4: 5 grams of the product from example 2 were mixed with 1.30g of IPDA before undergoing a cooking cycle of 1 hour at 80°C followed by 2 hours at 180°C.

[0126] Example 5 5 grams of the product from example 3 were mixed with 1.27g of IPDA before undergoing a cooking cycle of 1 hour at 80°C followed by 2 hours at 180°C

[0127] The glass transition temperature and the water reabsorption of the crosslinked products thus obtained were measured.

[0128] The results are presented in Table 2. [Table 2] Polyepoxide Water refilling Tg 2nd heating (°C) Example 4 2.39% 70 Example 5 10.9% 98 Example 6 3% 83 Example 7 13% 99 Example 8 25% 110

[0129] For comparison, crosslinking of isosorbide glycidyl ether / CHDM glycidyl ether mixtures was carried out.

[0130] Example 6:5 grams of a composition comprising 25% by mol of isosorbide diglycidyl ether (EEW=189g / eq) and 75% by mol of CHDM diglycidyl ether (EEW=159g / eq) were vigorously mixed for 5 minutes with 1.28g of IPDA before undergoing an oven curing cycle of 1 hour at 80°C followed by 2 hours at 180°C

[0131] Example 7: 5 grams of a composition comprising 75% by mol of isosorbide diglycidyl ether (EEW=189g / eq) and 25% by mol of CHDM diglycidyl ether (EEW=159g / eq) were vigorously mixed for 5 minutes with 1.17g of IPDA before undergoing an oven-baking cycle of 1 hour at 80°C followed by 2 hours at 180°C.

[0132] The glass transition temperature and the water reabsorption of the crosslinked products thus obtained were measured.

[0133] The results are presented in Table 2.

[0134] Comparison of the materials according to the invention and materials made from mixtures of epoxy prepolymers shows that the former have better water resistance (lower water absorption).

[0135] For comparison, the crosslinking of an isosorbide diglycidyl ether using IPDA was carried out.

[0136] Example 8 5 grams of isosorbide diglycidyl ether (EEW=189g / eq) were vigorously mixed for 5 minutes with 1.12g of IPDA before undergoing a 1-hour oven heating cycle at 80°C followed by 2 hours at 180°C

[0137] Comparison of the materials according to the invention and the polyepoxide obtained from isosorbide diglycidyl ether alone shows that the former have a significantly improved water resistance and a reduced thermal resistance.

Claims

1. A method for preparing an epoxy prepolymer composition comprising glycidyl ethers, said method comprising the following steps: a) Placing a dianhydrohexitol into contact with another alcohol so as to obtain a composition of alcohols; b) Reacting the composition of alcohols obtained in step a) with an epihalohydrin so as to obtain a reaction mixture comprising glycidyl ethers; c) Recovering the epoxy prepolymer composition comprising glycidyl ethers from the reaction mixture obtained at the end of step b).

2. The method according to claim 1, characterized in that the dianhydrohexitol is an isohexitol, preferably selected from isosorbide, isomannide or isoidide, and is, more preferably, isosorbide.

3. The method according to any one of the preceding claims, characterized in that the other alcohol is selected from the following alcohols: - Trimethylol ethane, - Trimethylol propane, - Spiroglycol, - Tricyclodecanedimethanol, - Glycerol, - Hexan-1,6-diol, - Cn aliphatic diols, wherein n ≥ 7, - Cyclohexan-1, m-dimethanol, where m = 2, 3 or 4, - Furan-p,q-dimethanol, where {p,q} = {1,4}, {1,3} or {2,3}, - Thiophen-p,q-dimethanol, where {p,q} = {1,4}, {1,3} or {2,3}, - Isoborneol, - Dodecanol, or - Decanol.

4. The method according to any one of the preceding claims, characterized in that the other alcohol comprises at least two alcohol functions.

5. The method according to any one of the preceding claims, characterized in that a polyepoxide obtained by a method for curing an epoxy prepolymer composition obtained by a method for the etherification of the other alcohol with an epihalohydrin, preferably has a water uptake lower than the water uptake, measured according to the same method, of a polyepoxide obtained by the same curing and etherification methods but by replacing the other alcohol with dianhydrohexitol.

6. The method according to any one of the preceding claims, characterized in that the epihalohydrin is selected from epibromohydrin, epifluorohydrin, epiiodohydrin, epichlorhydrin, or mixtures thereof, preferably epihalohydrin is epichlorhydrin.

7. The method according to any one of the preceding claims, wherein step b) of reacting the composition of alcohols with epihalohydrin comprises the following steps: b1) Placing the composition of alcohols into contact with epihalohydrin so as to obtain a reaction mixture; b2) Placing the reaction mixture obtained in step b1) under vacuum so as to obtain a negative pressure comprised between 100 mbar and 1,000 mbar; b3) Heating the reaction mixture obtained in step b2), while maintaining said negative pressure, at a temperature comprised between 50°C and 120°C, so as to achieve distillation of the epihalohydrate; b4) Adding a basic reagent to the reaction mixture obtained in step b3) for a period comprised between 1 hour and 10 hours while maintaining the reaction mixture at said negative pressure and at said temperature so as to achieve azeotropic distillation of the water-epihalohydrin azeotrope.

8. The method according to claim 7, characterized in that the basic reagent is selected from lithium, potassium, calcium or sodium hydroxides, preferably in the form of an aqueous solution, and is more preferably an aqueous sodium hydroxide solution.

9. The method according to claims 7 or 8, characterized in that a phase-transfer catalyst is added during step b1).

10. The method according to claim 9, characterized in that the phase-transfer catalyst is selected from halides, tetraalkyl ammonium sulfates or hydrogen sulfates, preferably from tetrabutylammonium bromide or tetrabutylammonium iodide.

11. The method according to any one of claims 9 or 10, characterized in that the amount of phase-transfer catalyst is comprised between 0.01 and 5%, preferably between 0.1% and 2%, more preferably is 1% by weight relative to the total represented by the sum of the masses of the dianhydrohexitol and of the other alcohol.

12. The method according to any one of the preceding claims, characterized in that step c) comprises a step of filtering the reaction medium obtained at the end of step b) so as to obtain a filtrate comprising the epoxy prepolymer composition, preferably said filtration step is followed by a step of concentrating the filtrate and / or a step of purifying the filtrate.

13. An epoxy prepolymer composition that can be obtained by the method according to any one of the preceding claims.

14. A curable composition comprising the epoxy prepolymer composition according to claim 13, characterized in that it further comprises at least one accelerating agent and / or at least one curing agent, preferably said curable composition comprises an amine-type curing agent, more preferentially the curing agent is isophorone diamine.

15. The curable composition according to claim 14, characterized in that the accelerating agents and / or curing agents are directly incorporated into the epoxy prepolymer composition.

16. The curable composition according to claim 15, characterized in that the accelerating agents and / or the curing agents are packaged separately from the epoxy prepolymer composition.

17. A polyepoxide obtained by curing the curable composition according to any one of claims 14 to 16.

18. A composite, coating or adhesive material comprising the polyepoxide according to claim 17.