Two-component adhesive formulation based on (meth)acrylate for the assembly of wind turbine blades

Abstract

The invention relates to a two-component adhesive formulation comprising: A composition (A) comprising: - from 70% to 99.98% by weight of a (meth)acrylic liquid syrup comprising: a) a (meth)acrylic polymer, b) a (meth)acrylic monomer, said (meth)acrylic liquid syrup having a dynamic viscosity ranging from 10 mPa*s to 10,000 mPa*s, - from 0.01% to 12% by weight of at least one urethane-methacrylate oligomer having a functionality greater than or equal to 2, - at least one activator, A composition (B) comprising a radical initiator, said initiator forming, upon contact with said activator, a system capable of initiating the polymerization of the (meth)acrylic monomer of composition (A). Figure for abstract: none

Description

Title of the invention: Two-component adhesive formulation based on (meth)acrylate for the assembly of wind turbine blades Field of the invention

[0001] The present invention relates to a two-component adhesive formulation based on methacrylate, and its use as a structural adhesive, in particular for the repair and / or assembly of composite parts such as wind turbine blades or components thereof. Technical background

[0002] Existing adhesives in the wind power sector are mainly based on thermosetting resins such as epoxy, vinylester or polyurethane resins.

[0003] Some disadvantages could limit the use of these products in the future. The wind industry is looking for greater productivity, especially since molds represent a significant investment, especially heated molds. Manufacturers are looking to reduce the initial investment and minimize the downtime of these molds. Epoxy adhesives in particular require the input of heat to complete their polymerization and immobilize heated molds for long hours. Another limitation concerns recyclability. Today, there is no suitable recycling solution for these thermosetting resins and the blades end up buried in the ground.

[0004] Furthermore, it is important to develop adhesives that are sufficiently resistant to the chemical and mechanical stresses to which the blades are subjected during operation.

[0005] There is therefore a real need to provide adhesive formulations for the wind power sector, making it possible to at least partially overcome at least one of the aforementioned drawbacks.

[0006] In particular, there is a need for adhesive formulations having good mechanical and adhesive properties, in particular over a wide temperature range.

[0007] There is also a need to provide such formulations which are further recyclable to allow recycling of wind turbine blades. Summary of the invention

[0008] The present invention relates to a two-component adhesive formulation comprising: - A composition (A) comprising:

[0009] - from 70% to 99.98% by weight of a (meth)acrylic liquid syrup comprising:

[0010] a) a (meth)acrylic polymer,

[0011] b) a (meth)acrylic monomer,

[0012] said (meth)acrylic liquid syrup having a dynamic viscosity ranging from 10 mPa*s to 10,000 mPa*s,

[0013] - from 0.01% to 12% by weight of at least one urethane-(meth)acrylate oligomer having a feature greater than or equal to 2,

[0014] - at least one activator, - A composition (B) comprising a radical initiator,

[0015] said initiator forming, upon contact with said activator, a system capable of initiating the polymerization of the (meth)acrylic monomer of composition (A).

[0016] According to other optional and / or preferential characteristics of the two-component adhesive formulation, to be considered in isolation or in combination: - the (meth)acrylic polymer is a methyl methacrylate (MMA) copolymer comprising at least 70%, preferably at least 80%, advantageously at least 90% and more advantageously at least 95% by weight of methyl methacrylate (MMA); - the (meth)acrylic polymer comprises a comonomer, said comonomer being an alkyl acrylate, the alkyl group having from 1 to 12 carbon atoms, in particular from 1 to 4 carbon atoms; - the (meth)acrylic polymer is a copolymer of methyl methacrylate and ethyl acrylate (MMA / EA); - the liquid syrup comprises from 40% to 90% by weight, preferably from 50% to 90% by weight, advantageously from 55% to 85% by weight and more advantageously from 60% to 85% by weight of (meth)acrylic monomer relative to the total weight of the (meth)acrylic liquid syrup; - the urethane-(meth)acrylate oligomer has a transition temperature vitreous Tg between 100 and 150°C, preferably between 110°C and 130°C; - the urethane-(meth)acrylate oligomer has a molar mass less than 1500 g.mol1, especially less than 1000 g.mol1; - composition (A) comprises from 0.01% to 10% by weight, more preferably from 0.1% to 7% by weight, and even more preferably from 0.5% to 5% by weight of urethane-(meth)acrylate oligomer relative to the total weight of composition (A); - composition (A) comprises from 0% to 40% by total weight of additive(s), preferably from 1% to 30% by weight relative to the total weight of said composition (A); - composition (A) comprises, relative to the total weight of composition (A): • from 70% to 95% by weight of (meth)acrylic liquid syrup, preferably from 70% to 90% by weight of (meth)acrylic liquid syrup; • from 0.1% to 7% by weight of urethane-(meth)acrylate oligomer(s); • from 0.1% to 5% by weight of activator(s); • from 0% to 30% by weight of additive(s), preferably from 1% to 30% by weight of additive(s); - composition (A) comprises, in relation to the total weight of composition (A): • from 70% to 95% by weight of (meth)acrylic liquid syrup, preferably from 70% to 90% by weight of (meth)acrylic liquid syrup; • from 0.1% to 5% by weight of urethane-(meth)acrylate oligomer(s); • from 0.1% to 5% by weight of activator(s); • from 0.1% to 10% by weight of phytogenic agent(s); • from 0.1% to 10% by weight of impact modifier(s);

[0017] - composition (B) comprises, relative to the total weight of composition B:

[0018] - from 5% to 40% by weight of initiator;

[0019] - from 60% to 95% by weight of additives.

[0020] - composition (B) comprises: • from 5% to 40% by weight of initiator; • from 40% to 75% by weight of additives chosen from non-reactive diluents, plasticizers and their mixtures, the non-reactive diluent(s) preferably being epoxy resins and functionalized vegetable oils; • from 0% to 25% by weight of other additive(s) such as for example rheological agent(s).

[0021] The invention also relates to a method for preparing an article comprising at least two assembled substrates, said method comprising: i. The mixture of compositions (A) and (B) of the adhesive formulation according to the invention; ii. Applying the resulting mixed adhesive formulation between a first and a second substrate; iii. Polymerizing the mixed adhesive formulation between the first and second substrates, whereby the two substrates are joined.

[0022] The invention also relates to an article capable of being obtained according to this method.

[0023] Another subject of the invention relates to the use of a two-component adhesive formulation according to the invention for the preparation and / or repair and / or assembly of composite parts such as wind turbine blades or components thereof.

[0024] The invention also relates to a wind turbine blade comprising a two-component adhesive formulation according to the invention polymerized by mixing compositions (A) and (B), said polymerized two-component formulation being simultaneously in contact with a first substrate and a second substrate of a wind turbine blade.

[0025] The two-component adhesive composition based on (meth)acrylate can advantageously be polymerized at room temperature (23°C) without the addition of heat, which makes it possible to avoid the use of heated molds and their immobilization for long hours. The adhesive composition according to the invention advantageously allows a reduction in costs and a gain in productivity during the bonding phases.

[0026] The two-component adhesive composition based on (meth)acrylate advantageously leads to an adhesive layer having good mechanical and adhesive properties, in particular over a wide temperature range (for example from -40°C to +50°C). More particularly, it has been demonstrated that the polymerization of a liquid syrup based on (meth)acrylate in the presence of a urethane-(meth)acrylate oligomer advantageously makes it possible to limit fining, in particular at high temperature, in particular at a temperature above 50°C. Furthermore, the adhesive compositions advantageously meet certain criteria set by the DNV organization, the main certification organization for the wind industry.

[0027] In addition, the adhesive layer obtained from the two-component formulations has a high glass transition temperature (Tg), in particular greater than 50°C, which advantageously gives it stable behavior, in particular in terms of temperature resistance and finishing, in a wide temperature range, in particular compatible with use in the wind power sector.

[0028] These two-component adhesive formulations are thus particularly advantageous for the preparation, repair and / or assembly of composite parts such as wind turbine blades or components thereof.

[0029] Finally, the (meth)acrylic polymers of the polymerized adhesive formulations can advantageously be recycled by chemical treatment and the recovered methacrylate monomers recycled in other industrial fields and / or potentially in the wind power field. Description of the invention

[0030] Thus, according to a first aspect, the invention relates to a two-component adhesive formulation comprising: - A composition (A) comprising:

[0031] - from 70% to 99.98% by weight of a (meth)acrylic liquid syrup comprising:

[0032] a) a (meth)acrylic polymer,

[0033] b) a (meth)acrylic monomer,

[0034] said (meth)acrylic liquid syrup having a dynamic viscosity ranging from 10 mPa*s to 10,000 mPa*s,

[0035] - from 0.01% to 12% by weight of at least one urethane-(meth)acrylate oligomer having a feature greater than or equal to 2,

[0036] - an activator, - A composition (B) comprising a radical initiator,

[0037] said radical initiator forming, upon contact with said activator, a system capable of initiating the polymerization of the (meth)acrylic monomer of composition (A).

[0038] In the remainder of the description, by “polymer” is meant either a copolymer or a homopolymer.

[0039] The term "monomer" as used refers to a molecule that can undergo polymerization.

[0040] The term “copolymer” means a polymer grouping together several different monomer units.

[0041] The term "polymerization" as used refers to the process of transforming a monomer or mixture of monomers into a polymer.

[0042] The term “homopolymer” means a polymer grouping together identical monomer units.

[0043] The term "block copolymer" means a polymer comprising one or more uninterrupted sequences of each of the distinct polymer species, the polymer sequences being chemically different from one or more of the other(s) and being linked together by a covalent bond.

[0044] The term "(meth)acrylic" as used refers to any type of acrylic and methacrylic compounds, polymers, monomers or oligomers. However, it would not be outside the scope of the invention if the (meth)acrylic matrix and / or the (meth)acrylic block copolymer comprise up to 10% by weight, preferably less than 5% by weight of other non-acrylic monomers, chosen from the group: butadiene, isoprene, cyclosiloxanes, vinylnaphthalenes and vinyl pyridines.

[0045] The term "thermoplastic polymer" as used refers to a polymer having a glass transition temperature Tg above room temperature (23°C).

[0046] The term "thermosetting polymer" as used refers to a plastic material that irreversibly transforms upon polymerization into an insoluble polymer network.

[0047] For the purposes of the invention, an “oligomer” is a small polymer compound, comprising between 2 and 30 monomers, i.e. whose degree of polymerization is between 2 and 30.

[0048] The term "initiator" as used, refers to a chemical species that reacts with a monomer to form an intermediate compound capable of binding successively with a large number of other monomers to form a polymer. The initiator is a radical initiator, in particular a redox initiator, that is to say an initiator for which the production of radicals results from an oxidation-reduction reaction. The oxidation-reduction reaction can in particular result from contact with an activator.

[0049] The term "activator" as used, refers to a chemical species capable of activating or accelerating the polymerization reaction, in particular by acting on the radical initiator. The activator generally makes it possible to activate the polymerization reaction at room temperature (23°C) without an external heat supply being necessary.

[0050] The formulation according to the invention is a “two-component” composition, i.e. a formulation separated into two parts to prevent it from polymerizing by itself. A first part, in this case composition (A), comprises the polymerizable species such as (meth)acrylate monomers and urethane-methacrylate oligomers, while a second part, in this case composition (B), comprises the radical initiator of the polymerization reaction. Thus, composition (B) may comprise a redox initiator, in particular an oxidizing initiator, which will be activated upon contact with an activator, in particular a reducing initiator, present in composition (A). The initiation of the polymerization reaction can therefore only occur when composition (B) comprising the radical / oxidizing initiator and composition (A) comprising the activator / reducing agent are brought into contact with each other. (Meth)acrylic polymer

[0051] The (meth)acrylic polymer may be a polyalkyl methacrylate or a polyalkyl acrylate. In a preferred embodiment, the (meth)acrylic polymer is a polymethyl methacrylate (PMMA).

[0052] The term "PMMA" as used means the homopolymer or copolymer of methyl methacrylate or a mixture thereof.

[0053] The (meth)acrylic polymer may be a homo- or copolymer of methyl methacrylate or a mixture thereof.

[0054] According to one embodiment, the methyl methacrylate (MMA) copolymer comprises at least 70%, preferably at least 80%, advantageously at least 90% and more advantageously at least 95% by weight of methyl methacrylate (MMA).

[0055] According to another embodiment, the methyl methacrylate (MMA) copolymer comprises from 70% to 99.7% by weight, preferably from 80% to 99.7% by weight, advantageously from 90% to 99.7% by weight and more advantageously from 90% to 99.5% by weight of methyl methacrylate and from 0.3 to 30% by weight, preferably from 0.3% to 20% by weight, advantageously from 0.3% to 10% by weight and more advantageously from 0.5% to 10% by weight of at least one monomer having at least one ethylenic unsaturation which can be copolymerized with methyl methacrylate.

[0056] According to another embodiment, the (meth)acrylic polymer comprises a comonomer, said comonomer being an alkyl acrylate, the alkyl group having from 1 to 12 carbon atoms, in particular from 1 to 4 carbon atoms. By way of example, mention may in particular be made of methyl acrylate, ethyl acrylate or a mixture thereof.

[0057] The average molecular weight of the (meth)acrylic polymer is preferably greater than 50,000 g / mol, and even more preferably greater than 100,000 g / mol.

[0058] The average molecular weight can in particular be measured by size exclusion chromatography.

[0059] According to a preferred embodiment, the (meth)acrylic polymer is a copolymer of methyl methacrylate and ethyl acrylate (MMA / EA). Preferably, this copolymer has an average molecular weight of between 50,000 g / mol and 200,000 g / mol, even more preferably between 100,000 g / mol and 150,000 g / mol. (Meth)acrylic monomer

[0060] The (meth)acrylic monomer may be chosen from acrylic acid, methacrylic acid, alkyl acrylate monomers, alkyl methacrylate monomers or mixtures thereof, the alkyl group having from 1 to 22 carbon atoms, preferably from 1 to 12 carbon atoms, and being linear, branched or cyclic.

[0061] Advantageously, the (meth)acrylic monomer is chosen from methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, methacrylic acid, acrylic acid, n-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, isobutyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate or mixtures thereof.

[0062] More advantageously, the (meth)acrylic monomer is chosen from methyl methacrylate, isobornyl acrylate, acrylic acid or mixtures thereof. It is more preferably methyl methacrylate.

[0063] According to a preferred embodiment, at least 50% by weight, preferably at least 75% by weight, and even more preferably at least 90% of the (meth)acrylic monomer is methyl methacrylate. (Meth)acrylic liquid syrup

[0064] The viscosity of the (meth)acrylic liquid syrup is high due to the presence of (meth)acrylic monomers or a mixture of (meth)acrylic monomers forming a matrix in which one or more polymers are dissolved. (meth)acrylics. This solution is commonly referred to as “syrup” or “prepolymer”.

[0065] Advantageously, the (meth)acrylic liquid syrup does not contain any solvent. additional.

[0066] Preferably, the (meth)acrylic polymer is completely soluble in the (meth)acrylic monomer.

[0067] The liquid (meth)acrylic syrup can be prepared by simply mixing the polymer (meth)acrylic and (meth)acrylic monomer, for example at 25°C.

[0068] The (meth)acrylic polymer is PMMA, i.e. homo- or copolymer of methyl methacrylate (MMA) or a mixture thereof, as defined above.

[0069] The (meth)acrylic polymer in the (meth)acrylic liquid syrup may represent at least 10% by weight, preferably at least 15% by weight, advantageously at least 18% by weight, more advantageously at least 20% by weight of the total weight of the (meth)acrylic liquid syrup.

[0070] By “total weight of the (meth)acrylic liquid syrup” is meant the weight consisting of the (meth)acrylic monomer and the (meth)acrylic polymer, the (meth)acrylic monomer and the (meth)acrylic polymer being as defined in the present description.

[0071] The (meth)acrylic polymer in the (meth)acrylic liquid syrup may represent at most 60% by weight, preferably at most 50% by weight, advantageously at most 40%, more advantageously at most 35% by weight of the total weight of the (meth)acrylic liquid syrup.

[0072] The (meth)acrylic monomer in the (meth)acrylic liquid syrup may represent at least 40% by weight, preferably at least 50% by weight, advantageously at least 60%, more advantageously at least 65% by weight of the total weight of the (meth)acrylic liquid syrup.

[0073] The (meth)acrylic monomer in the (meth)acrylic liquid syrup may represent from 40% to 90% by weight, preferably from 50% to 90% by weight, advantageously from 55% to 85% by weight and more advantageously from 60% to 85% by weight of the total weight of the (meth)acrylic liquid syrup.

[0074] Accordingly, the (meth)acrylic polymer in the (meth)acrylic liquid syrup may represent from 10% to 60% by weight, preferably from 10% to 50% by weight, advantageously from 15% to 45% by weight and more advantageously from 15% to 40% by weight of the total weight of the (meth)acrylic liquid syrup.

[0075] The dynamic viscosity of the liquid (meth)acrylic syrup is in a range from 10 mPa*s to 10000 mPa*s, preferably 50 mPa*s.

[0076] to 5000 mPa*s and advantageously from 100 mPa*s to 1000 mPa*s. The viscosity of the syrup can be easily measured with a rheometer or a viscometer. The viscosity dynamic is measured at 25°C. Liquid (meth)acrylic syrup has Newtonian behavior, so that dynamic viscosity is independent of shear in a rheometer or spindle speed in a viscometer. Urethane-(meth)acrylate oligomer

[0077] Composition (A) of the adhesive formulation according to the invention comprises a urethane-(meth)acrylate oligomer having a functionality greater than or equal to 2.

[0078] By “functionality greater than or equal to 2” is meant an oligomer having at least two functions, in particular two unsaturations, such as two (meth)acryloyloxy alkylene functions, capable of copolymerizing with the (meth)acrylic monomer.

[0079] The urethane-(meth)acrylate oligomer may comprise one or more methane bonds (-OCONH-), in particular between polyether and / or polyester and / or polyol blocks.

[0080] According to a preferred embodiment, the urethane-(meth)acrylate oligomer comprises at least two (meth)acryloyloxy alkylene terminal functions (-Alk-CO2-C(H / CH3)=CH2), the alkylene group (-Alk-) preferably having from 2 to 8, advantageously from 2 to 6, and more advantageously from 2 to 4 carbon atoms.

[0081] The urethane-(meth)acrylate oligomer may comprise a polyurethane comprising two terminal (meth)acryloyloxy alkylene functions (-Alk-CO2-C(H / CH3)=CH2), at each of the ends.

[0082] The urethane-(meth)acrylate oligomer may have a symmetrical tri-block BAB structure, comprising a central polyether block A linked by chemical bonds of two diisocyanate molecules, to respectively two terminal hydrophobic blocks B based on hydrophobic polyester oligomers, having a terminal (meth)acryloyloxyalkylene group.

[0083] More particularly, said polyurethane oligomer has the following general formula (1):

[0084] B-OCONH-R-NHCOO-A-OCONH-R-NHCOO-B (1)

[0085] In which:

[0086] A is the residue of a polyether diol

[0087] OCONH-R-NHCOO: urethane bond formed by the reaction of said polyether diol with a diisocyanate compound R-(NCO)2, in which:

[0088] R is a divalent aromatic, aliphatic or cycloaliphatic group, preferably aliphatic, in particular having at least 6 carbon atoms or R has a cycloaliphatic structure including in particular a hydrogenated aromatic structure,

[0089] B is the residue of a hydrophobic polyester oligomer, preferably a polycaprolactone oligomer, carrying in the terminal position a (meth)acryloyloxy alkylene group linked to said polyester oligomer chain, preferably polycaprolactone oligomer, by an ester bond (-CO2).

[0090] According to another embodiment, the urethane-(meth)acrylate oligomer results from an esterification reaction of a polyurethane polyol or polyurethane monool with acrylic or methacrylic acid or from a reaction of a polyurethane polyisocyanate prepolymer and a hydroxyalkyl (meth)acrylate.

[0091] The urethane-(meth)acrylate oligomer may have a glass transition temperature Tg of between 100 and 150°C, preferably between 110°C and 130°C, as measured in particular by dynamic mechanical analysis, also called DMA.

[0092] The urethane-(meth)acrylate oligomer may have a molar mass of less than 1500 g.mol1, in particular less than 1000 g.mol1.

[0093] Preferably, the urethane-(meth)acrylate oligomer represents from 0.01% to 10% by weight, more preferably from 0.1% to 7% by weight, and even more preferably from 0.5% to 5% by weight of the total weight of the composition (A).

[0094] Reference may be made to the urethane-(meth)acrylate oligomers marketed by the company SARTOMER, for example under the name CN1993 CG or CN 1963CG. Polymerization initiator

[0095] The initiator for initiating the polymerization reaction of the monomers and oligomers present in composition (A) is a radical initiator, i.e. an initiator generating radicals for which the production of radicals results in particular from an oxidation-reduction reaction.

[0096] Thus, the radical initiator may be a redox initiator. Preferably, this reacts according to an oxidation-reduction reaction with an activator present in composition (A), to generate free radicals and initiate the polymerization of the (meth)acrylic monomers and urethane-(meth)acrylate oligomers.

[0097] Preferably, the radical initiator is chosen from peroxides or diperoxides having from 2 to 20 carbon atoms, and even more preferably the radical initiator is benzoyl diperoxide or cumene hydroperoxide.

[0098] The content of radical initiator may be greater than or equal to 5% by weight, preferably ranging from 5% to 40% by weight relative to the total weight of the composition (B). The content of radical initiator is understood as a percentage by weight of active material relative to the total weight of the composition (B). Polymerization activator

[0099] The adhesive formulation comprises a polymerization activator. As previously indicated, the activator advantageously reacts with the radical initiator to generate the formation of radicals, in particular via an oxidation-reduction reaction, preferably at room temperature (23°C).

[0100] The activator may be chosen from tertiary amines such as, for example, N,N-dimethyl-p-toluidine (DMPT), or N,N-dihydroxyethyl-p-toluidine (DHEPT).

[0101] Composition (A) may comprise a total weight of activator(s) ranging from 0.1% to 5% by weight relative to the total weight of composition (A). Additives of composition (A)

[0102] Composition (A) may comprise one or more additives.

[0103] Examples of additives include organic additives such as impact modifiers or block copolymers, heat stabilizers, UV stabilizers, lubricants, rheology agents, film-forming agents, adhesion promoters, flame retardants, and mixtures thereof; and inorganic additives such as inorganic fillers.

[0104] Composition (A) may comprise from 0% to 40% by total weight of additive(s), preferably from 1% to 30% by weight relative to the total weight of said composition (A).

[0105] The impact modifier may be in the form of fine particles having an elastomeric core and at least one thermoplastic shell, the particle size generally being less than 1 pm and advantageously between 50 and 300 nm. The impact modifier may be prepared by emulsion polymerization.

[0106] The total content of impact modifier(s) in composition (A) may range from 0% to 50% by weight, preferably from 0% to 25% by weight, and advantageously from 1% to 20% by weight relative to the total weight of said composition (A).

[0107] Among the impact modifiers, we can for example cite the “core-shell” base MBS MMA-butadiene-styrene, and ABS.

[0108] Preferably, composition (A) comprises an impact modifier.

[0109] Preferably, composition (A) comprises a film-forming agent making it possible to limit the reaction of unsaturated compounds contained in the adhesive formulation with the oxygen in the air and obtain a longer open time before polymerization of the adhesive formulation.

[0110] Preferably, the film-forming agent is a mixture of waxes, such as paraffins, comprising polar compounds such as isodecyl ether and polyoxyethylene.

[0111] By "open time" is meant as used, the duration between the start of mixing of compositions (A) and (B) and the start of polymerization of the adhesive formulation, duration during which the user can apply the formulation to the substrate(s) that he wishes to assemble.

[0112] Advantageously, the adhesive formulations according to the invention make it possible to have an open time greater than or equal to 20 minutes, or even greater than or equal to 1 hour.

[0113] Composition (A) may comprise from 0% to 20% by total weight of film-forming agent(s), preferably from 0.1% to 10% by weight, and even more preferably from 0.1% to 5% by weight relative to the total weight of said composition (A).

[0114] Examples of heat stabilizers include hydroquinone (HQ), methyl hydroquinone (MEHQ), 2,6-di-tertiarybutyl-4-methoxyphenol (Topanol 0) and 2,4-dimethyl-6-tertiarybutyl phenol (Topanol A). These heat stabilizers prevent the monomers in formulation (A) from spontaneously polymerizing.

[0115] As an example of rheology agent(s), mention may be made of any rheology agent usually used in the field of adhesive compositions.

[0116] Preferably, the rheology agents are chosen from: - PVC plastisols, corresponding to a suspension of PVC in a plasticizing agent miscible with PVC, obtained in situ by heating at temperatures ranging from 60°C to 80°C. These plastisols may be those described in particular in the work “Polyurethane Sealants”, Robert M. Evans, ISBN 087762-998-6, - fumed silica, such as for example sold under the name HDK® N20 by WACKER; - urea derivatives resulting from the reaction of an aromatic diisocyanate monomer such as 4,4'-MDI with an aliphatic amine such as butylamine. The preparation of such urea derivatives is described in particular in application FR 1 591 172; - micronized amide waxes, such as CRAYVALLAC® SLT or CRAYVALLAC® SLA marketed by ARKEMA.

[0117] The adhesion promoters may be chosen from silanes, such as aminosilanes, epoxysilanes or acryloyl silanes, or adhesion promoters based on phosphate ester such as, for example, 2-hydroxyethyl methacrylate phosphate ester, 2-methacryloyloxyethyl phosphate, bis-(2-methacryloyloxyethyl phosphate), 2-acryloyloxyethyl phosphate, bis-(2-acryloyloxyethyl phosphate), methyl-(2-methacryloyloxyethyl phosphate), ethyl-(2-methacryloyloxyethyl phosphate), a mixture of mono- and di-phosphate esters of 2-hydroxyethyl methacrylate. Examples include JPA514 marketed by KOWA, SR9051 marketed by SARTOMER.

[0118] UV stabilizers are typically introduced to protect the composition from degradation resulting from a reaction with oxygen that is likely to form by the action of heat or light. These compounds may include primary antioxidants that scavenge free radicals. Primary antioxidants can be used alone or in combination with other secondary antioxidants or UV stabilizers.

[0119] Examples include IRGANOX ® 1010, IRGANOX ® B561, IRGANOX ® 245, IRGAFOS ® 168, TINUVIN® 328 or TINUVIN™ 770 marketed by BASF.

[0120] As an example of an inorganic filler, any mineral filler usually used in the field of adhesive compositions can be used. These fillers are typically in the form of particles of various geometry. They can be, for example, spherical, fibrous, or have an irregular shape.

[0121] The inorganic filler may be chosen from the group consisting of clay, quartz, carbonate fillers, kaolin, gypsum, clays, and mixtures thereof.

[0122] The inorganic filler may be untreated or treated, for example using an organic acid such as stearic acid, or a mixture of organic acids consisting predominantly of stearic acid.

[0123] It is also possible to use hollow mineral microspheres such as hollow glass microspheres, and more particularly those made of sodium and calcium borosilicate or aluminosilicate.

[0124] According to one embodiment, the composition (A) comprises, relative to the total weight of the composition (A): - from 70% to 95% by weight of (meth)acrylic liquid syrup, preferably from 70% to 90% by weight of (meth)acrylic liquid syrup; - from 0.1% to 7% by weight of urethane-(meth)acrylate oligomer(s); - from 0.1% to 5% by weight of activator(s); - from 0% to 30% by weight of additive(s), preferably from 1% to 30% by weight of additive(s).

[0125] According to a preferred embodiment, the composition (A) comprises, relative to the total weight of the composition (A): - from 70% to 95% by weight of (meth)acrylic liquid syrup, preferably from 70% to 90% by weight of (meth)acrylic liquid syrup; - from 0.1% to 5% by weight of urethane-(meth)acrylate oligomer(s); - from 0.1% to 5% by weight of activator(s); - from 0.1% to 10% by weight of film-forming agent(s); - from 0.1% to 10% by weight of impact modifier(s). Additives of composition (B)

[0126] Composition (B) may comprise one or more additives.

[0127] Examples of additives include organic additives such as non-reactive diluents, heat stabilizers, UV stabilizers, lubricants, rheology agents, film-forming agents, plasticizers, adhesion promoters, flame retardants, and mixtures thereof; and inorganic additives such as inorganic fillers.

[0128] The description of the additives of composition (A) above applies to the additives also cited in composition (B).

[0129] According to one embodiment, the composition (B) comprises, relative to the total weight of the composition (B): - from 5% to 40% by weight of initiator; - from 60% to 95% by weight of additives.

[0130] Among the non-reactive diluents, we can for example cite epoxy resins, functionalized vegetable oils, and their mixtures.

[0131] The epoxy resin may be aliphatic, cycloaliphatic, heterocyclic or aromatic.

[0132] The epoxy resin can be monomeric or polymeric.

[0133] Epoxy resin covers any functionalized or non-functionalized epoxy resin, such as for example elastomer-modified epoxy resins which are typically obtained by reaction between a base epoxy resin with an elastomer comprising terminal functions reactive with the epoxy functions.

[0134] The epoxy resin can be chosen from:

[0135] - polyglycidyl ethers of polyphenolic compounds, preferably comprising 2 to 6 glycidyl ether functions per mole of resin,

[0136] - their derivatives (typically elastomer-modified resins); and

[0137] - their mixtures.

[0138] A polyphenolic compound is a compound having at least two aromatic hydroxyl groups.

[0139] The polyphenolic compounds may be selected from the group consisting of resorcinol, catechol, hydroquinone, bisphenol A (2,2-bis-(4-hydroxyphenyl)propane), bisphenol AP (1,1-bis-(4-hydroxyphenyl)-1-phenylethane), bisphenol AF (2,2-bis-(4-hydroxyphenyl)-hexafluoropropane), bisphenol B (2,2-bis-(4-hydroxyphenyl)butane), bisphenol BP (bis-(4-hydroxyphenyl)-diphenylmethane), bisphenol C (2,2-bis-(3-methyl-4-hydroxyphenyl)propane), bisphenol C11 (bis(4-hydroxyphenyl)-2,2-dichloroethylene), bisphenol E (1,1-bis-(4-hydroxyphenyl)ethane), bisphenol F (bis(4-hydroxyphenyl)-2,2-dichloroethylene), bisphenol FL (4,4'-(9H-fluoren-9-ylidene)bisphenol, bisphenol G (2,2-bis-(4-hydroxy-3-isopropylphenyl)propane), bisphenol M (1,3-bis-(2-(4-hydroxyphenyl)-2-propyl)benzene), bisphenol P (1,4-bis(2-4-hydroxyphenyl)-2-propyl)benzene), bisphenol PH (5,5'-(l-methylethylidene)-bis[l,l'-(bisphenyl)-2ol]propane), bisphenol S (bis(4-hydroxyphenyl)sulfone), bisphenol TMC (l,l-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane); bisphenol Z (l,l-bis(4-hydroxyphenyl)cyclohexane), bisphenol K, tetraethylbiphenol, and mixtures thereof.

[0140] Many epoxy resins are typically commercially available. Examples include DER™ 331, DER™ 383 resins marketed by DOW CHEMICALS, EPON 862 resin marketed by HEXION SPECIALITY CHEMICALS, EPOSIR® resins based on bisphenol A marketed by SIR INDUSTRIAL (for example EPOSIR® 7120, EPOSIR® resins based on bisphenol A / bisphenol F (for example EPOSIR® F556), STRUKTOL POLYDIS 3622 modified resins (CAS No. 25068-38-6) marketed by STRUKTOL, Araldite GY 250 marketed by HUNTSMAN.

[0141] The functionalized vegetable oils can be epoxidized vegetable oils (containing at least one epoxy function).

[0142] As an example of a plasticizing agent that can be used, mention may be made of any plasticizing agent usually used in the field of adhesives such as, for example, epoxy resins, phthalates, benzoates, trimethylolpropane esters, trimethylolethane esters, trimethylolmethane esters, glycerol esters, pentaerythritol esters, naphthenic mineral oils, adipates, cyclohexyldicarboxylates, paraffinic oils, natural oils (optionally epoxidized), polypropylenes, polybutylenes, hydrogenated polyisoprenes, phenol alkyl sulfonates, and mixtures thereof.

[0143] The total content of non-reactive diluent(s) in composition (B) may range from 0% to 80%, preferably from 10% to 75%, even more preferably from 20% to 70% relative to the total weight of said composition (B).

[0144] Preferably, the composition (B) comprises, relative to the total weight of the composition (B): - from 5% to 40% by weight of initiator; - from 40% to 75% by weight of additives chosen from non-reactive diluents, plasticizers and their mixtures, the non-reactive diluent(s) preferably being epoxy resins and functionalized vegetable oils; - from 0% to 25% by weight of other additive(s) such as for example rheological agent(s).

[0145] Method for preparing an article comprising at least two assembled substrates

[0146] According to a second aspect, the invention relates to a method for preparing an article comprising at least two assembled substrates, said method comprising: i. The mixture of compositions (A) and (B) of the adhesive formulation as defined above; ii. Applying the resulting mixed adhesive formulation between a first and a second substrate; iii. Polymerizing the mixed adhesive formulation between the first and second substrates, whereby the two substrates are joined.

[0147] In step i), compositions (A) and (B) of the adhesive formulation may be mixed in a static mixer.

[0148] The volume ratio of compositions (A) / (B) can range from 20 / 1 to 1 / 1, it is preferably equal to 10 / 1.

[0149] In step ii), the formulation is generally applied before the start of the polymerization of the mixture of (A) and (B), i.e. during the open time.

[0150] The adhesive formulation is typically applied at the outlet of the mixer, for example on the blades or wind turbine components to be assembled.

[0151] Advantageously, the polymerization in step iii) is carried out at a temperature below 40°C, in particular between 10°C and 30°C, in particular at room temperature (23°C), in particular at the end of the open time, in particular without it being necessary to provide an external source of heat or humidity.

[0152] The first and / or second substrates may be independently chosen from composite materials, in particular acrylic-based, or metallic.

[0153] Advantageously, the first and second substrates are components of wind turbine blades or wind turbine blades.

[0154] Article comprising at least two assembled substrates

[0155] According to a third aspect, the invention relates to an article capable of being obtained according to the method as defined above, preferably a wind turbine blade or a component thereof.

[0156] According to yet another aspect, the invention relates to a wind turbine blade comprising a two-component adhesive formulation as defined in the present description, polymerized by mixing compositions (A) and (B), said polymerized two-component formulation being simultaneously in contact with a first substrate and a second substrate of a wind turbine blade.

[0157] Use for the preparation and / or repair, in particular the assembly of wind turbine blades.

[0158] According to yet another aspect, the invention relates to a two-component adhesive formulation as defined above for the preparation, repair and / or assembly of composite parts such as, for example, wind turbine blades or components thereof.

[0159] Recycling of articles comprising at least two assembled substrates

[0160] Regarding the recycling of the article comprising at least two assembled substrates, it can be carried out by grinding or depolymerizing the polymer resulting from the adhesive formulation.

[0161] Preferably, the article comprising the polymer is heated so as to cause pyrolysis or thermal decomposition of the PMMA and recovery of methyl methacrylate as a monomer.

[0162] The article may in particular be heated to a temperature between 200°C and 400°C.

[0163] Advantageously, at least 50% by weight of MMA present in the polymer is recovered after thermal decomposition.

[0164] Thus, according to yet another aspect, the invention relates to the use of a two-component adhesive formulation as defined above for the preparation or assembly of recyclable wind turbine blades, in particular by thermal depolymerization.

[0165] All the embodiments described above may be combined with each other. In particular, the various aforementioned constituents of the composition, and in particular the preferred embodiments of the composition, may be combined with each other.

[0166] In the context of the invention, by "between x and y", or "ranging from x to y", is meant an interval in which the limits x and y are included. For example, the range "between 0% and 25%" includes in particular the values ​​0% and 25%. Examples

[0167] The following ingredients were used:

[0168] - Urethane-methacrylate U1 of functionality 2 with an Mw between 500 and 1 000 g / mol and a Tg between 100°C and 150°C marketed by SARTOMER;

[0169] - Impact modifier Ml marketed by ARKEMA (base block copolymer MBS MMA-butadiene-styrene);

[0170] - SR9054 (CAS No.: 1628778-81-3) marketed by SARTOMER: promoter difunctional acrylic acid adhesion;

[0171] - BISOMER® PTE (CAS No.: 103671-44-9) amine activator marketed by GEO Specialty Chemicals;

[0172] - Crayvallac® SLT marketed by ARKEMA: wax rheology agent micronized amide;

[0173] - HDK®N20 (CAS No.: 112945-52-5) marketed by WACKER, silica hydrophilic pyrogenic;

[0174] - AEROSIL® R208 (CAS No.: 7631-86-9) marketed by EVONIK, silica hydrophobic pyrogenic;

[0175] - MEHQ (CAS No.: 150-76-5) marketed by CAMLIN (thermal stabilizer) radical reaction);

[0176] - TALKRON® CL40 (CAS No.: 14807-96-6) marketed by MINERALIA;

[0177] - BYK® 750N (CAS No.: 64742-55-8 and 61827-42-7) commercial film-forming agent by BYK CHEMIE;

[0178] - ARALDITE® GY250 (CAS No.: 1675-54-3) bisphenol A diglycidyl ether additive (DGEBA) marketed by HUNTSMAN;

[0179] - PEROXAN BP-Paste 50 PF1 50% active ingredient (CAS No.: 94-36-0) peroxide dibenzoyl (oxidant) marketed by PERGAN. Example 1: preparation of liquid syrup

[0180] A liquid syrup is prepared by dissolving 20 parts of a polymethyl methacrylate (BS520 from Arkema: MMA / ethyl acrylate copolymer) in 80 parts of methyl methacrylate (MMA) in the presence of MEHQ as a stabilizer. The liquid syrup obtained has a dynamic viscosity of 500 to 600 mPa.s at 25°C. Example 2: composition no. 1 (according to the invention)

[0181] In a reactor maintained under stirring, the different ingredients constituting component A are mixed in the proportions indicated in the following table at a temperature of 23°C.

[0182] In a reactor maintained under constant stirring, the different ingredients constituting B are mixed in the proportions indicated in the following table at 23°C. Composition 1 Component A Component B Ingredients % by weight (relative to the weight of A) Ingredients % by weight (relative to the weight of B) Liquid syrup of example 1 78.83 PEROXAN BP PASTE 50PF1 29.5 Urethane-methacrylate U1 1.0 ARALDITE GY 250 66 Impact modifier Ml 7.5 CRAYVALLA C® SLT 4.0 PEROXAN BP paste 50PF1 30 AEROSIL R208 4 HDKN20 3.50 TALC 1.5 MEHQ 0.07 SR9054 1.0 BYK® 750N 2.0 Bisomer® PTE 0.6 Total 100 Total 100

[0183] The mixing is carried out at room temperature (23°C), according to a component A / component B volume ratio of 10 / 1, with a static mixer.

[0184] Example 3: comparative composition no. 2 (without urethane-methacrylate)

[0185] In a reactor maintained under stirring, the different ingredients constituting component A are mixed in the proportions indicated in the following table at a temperature of 23°C.

[0186] In a reactor maintained under constant stirring, the different ingredients constituting B are mixed in the proportions indicated in the following table at 23°C Composition No. 2 (comparative) Component A Component B ingredients % by weight (compared to the weight of A) ingredients % by weight (compared to the weight of B) Liquid syrup from Example 1 81.63 PEROXAN BP P ASTE 50PF1 29.5 ARALDITE GY 250 66 Impact modifier Ml 6.0 CRAYVALLA C® SLT 2.5 PEROXAN® BP paste 50 PF1 30 AEROSIL R208 4 HDKN20 4.70 TALC 1.5 MEHQ 0.07 SR9054 1.0 BYK® 750N 2.0 Bisomer® PTE 0.6 Total 100 Total 100 Example 4: Bonding Test Results

[0187] The bonds are made on fiberglass composite sterigmas. On one sterigma, an area of ​​25 * 12.5mm was delimited using 3mm thick Teflon shims. This area was filled with the composition to be tested, then a second sterigma of the same material was laminated. The assembly was held by a clamp and placed in an air-conditioned room at 23 °C for one week before traction on a dynamometer. The purpose of traction on a dynamometer is to evaluate the maximum force (in MPa) to be exerted on the assembly to separate it. The use of a tensile machine makes it possible to subject a simple overlap joint placed between two rigid supports to a shear stress until rupture by exerting traction on the supports parallel to the surface of the assembly and to the main axis of the test piece. The result to be recorded is the force or stress at break.The shear stress is applied via the movable jaw of the machine. traction with a displacement at a speed of 5mm / min. This traction method is carried out as defined by the EN1465 standard of 2009. Creep test:

[0188] The creep test specimens are made on fiberglass composite sterigmas. On one sterigma, an area of ​​25*12.5mm was delimited using 3mm thick Teflon shims. This area was filled with the composition to be tested, then a second sterigma of the same material was laminated. The assembly was held by a clamp and placed in a climate-controlled room at 23°C for one week before being loaded on the creep bench. The aim is to evaluate the creep of the glue joint under stress at 60°C for 192 hours. This bench allows tensile creep tests to be carried out in a temperature-controlled chamber at 60°C. The applied force is 2MPa on one of the sterigmas.

[0189] The result to be recorded is the measurement of elongation of the glue joint (expressed in mm).

[0190] The properties obtained from compositions No. 1 (invention and No. 2 (comparative)) are summarized in the following table: Shear test at 23°C Shear test at -40°C Shear test at 50°C Creep at 60°C (192 h) F max (MPa) Fracture surface F max (MPa) Fracture surface F max (MPa) Fracture surface Composition Composition No. 1 (example 2) 15.2 DS 14.3 DS 12.4 RC 0.2 mm Composition No. 2 (example 3) 16.9 DS 16 DS 14.9 RC disassembly*

[0191] DS: delamination of the substrate

[0192] RC: cohesive rupture

[0193] Fmax: maximum force at the moment of bond failure.

[0194] *disassembly is the separation of the two sterigmas which make up the assembly

[0195] Composition No. 1 advantageously exhibits good adhesion properties after crosslinking, over a wide temperature range (23°C, from -40°C to 50°C). The values ​​are notably higher than 12 MPa, which is advantageously higher than the threshold value required by the DNV standard (DNVGL-CP-0086).

[0196] In addition, composition No. 1 according to the invention advantageously has better resistance to fining than comparative composition No. 2 which does not contain urethane-methacrylate. Indeed, the creep after 192 hours is advantageously less than 1 mm (0.2 mm), while composition No. 2 (comparative) leads to disassembly after 50 hours.

Claims

Claims

1. Two-component adhesive formulation comprising: - A composition (A) comprising: - from 70% to 99.98% by weight of a (meth)acrylic liquid syrup comprising: a) a (meth)acrylic polymer, b) a (meth)acrylic monomer, said (meth)acrylic liquid syrup having a dynamic viscosity ranging from 10 mPa*s to 10,000 mPa*s, - from 0.01% to 12% by weight of at least one urethane-(meth)acrylate oligomer having a functionality greater than or equal to 2, - at least one activator, - A composition (B) comprising a radical initiator, said initiator forming, upon contact with said activator, a system capable of initiating the polymerization of the (meth)acrylic monomer of the composition (A), characterized in that the composition (A) comprises: from 70% to 95% by weight of (meth)acrylic liquid syrup, preferably from 70% to 90% by weight of (meth)acrylic liquid syrup; - from 0.1% to 7% by weight of urethane-(meth)acrylate oligomer(s);- from 0.1% to 5% by weight of activator(s); - from 0% to 30% by weight of additive(s), preferably from 1% to 30% by weight of additive(s).;

2. A formulation according to claim 1, wherein the (meth)acrylic polymer is a methyl methacrylate (MMA) copolymer comprising at least 70%, preferably at least 80%, advantageously at least 90% and more advantageously at least 95% by weight of methyl methacrylate (MMA).

3. Formulation according to any one of claims 1 or 2, wherein the (meth)acrylic polymer comprises a comonomer, said comonomer being an alkyl acrylate, the alkyl group having from 1 to 12 carbon atoms, in particular from 1 to 4 carbon atoms.

4. A formulation according to any one of claims 1 to 3, wherein the (meth)acrylic polymer is a copolymer of methyl methacrylate and ethyl acrylate (MMA / EA).

5. A formulation according to any one of claims 1 to 4, wherein the liquid syrup comprises from 40% to 90% by weight, preferably from 50% to 90% by weight, advantageously from 55% to 85% by weight and more advantageously from 60% to 85% by weight of (meth)acrylic monomer relative to the total weight of the (meth)acrylic liquid syrup.

6. Formulation according to any one of claims 1 to 5, wherein the urethane-(meth)acrylate oligomer has a glass transition temperature Tg of between 100 and 150°C, preferably between 110°C and 130°C.

7. Formulation according to any one of claims 1 to 6, in which the urethane-(meth)acrylate oligomer has a molar mass of less than 1500 g.mol ', in particular less than 1000 g.mol1.

8. Formulation according to any one of claims 1 to 7, in which the composition (A) comprises from 0.5% to 5% by weight of urethane-(meth)acrylate oligomer relative to the total weight of the composition (A).

9. Formulation according to any one of claims 1 to 8, wherein the composition (A) comprises from 1% to 30% by weight of additives relative to the total weight of said composition (A).

10. Formulation according to any one of claims 1 to 9, in which the composition (A) comprises, relative to the total weight of the composition (A): - from 70% to 95% by weight of (meth)acrylic liquid syrup, preferably from 70% to 90% by weight of (meth)acrylic liquid syrup; - from 0.1% to 5% by weight of urethane-(meth)acrylate oligomer(s); - from 0.1% to 5% by weight of activator(s); - from 0.1% to 10% by weight of film-forming agent(s); - from 0.1% to 10% by weight of impact modifier(s).

11. Formulation according to any one of claims 1 to 9, in which composition (B) comprises, relative to the total weight of composition B: - from 5% to 40% by weight of initiator; - from 60% to 95% by weight of additives. said composition (B) preferably comprising: - from 5% to 40% by weight of initiator; - from 40% to 75% by weight of additives chosen from non-reactive diluents, plasticizers and their mixtures, the non-reactive diluent(s) preferably being epoxy resins and functionalized vegetable oils; - from 0% to 25% by weight of other additive(s) such as for example rheological agent(s).

12. A method of preparing an article comprising at least two joined substrates, said method comprising: i. Mixing compositions (A) and (B) of the adhesive formulation according to any one of claims 1 to 11; ii. Applying the thus obtained mixed adhesive formulation between a first and a second substrate; iii. Polymerizing the mixed adhesive formulation between the first and second substrates, whereby the two substrates are joined.

13. Article obtainable according to the method of claim

14. 1Z. Use of a two-component adhesive formulation according to any one of claims 1 to 11 for the preparation and / or repair and / or assembly of composite parts such as wind turbine blades or components thereof.

15. A wind turbine blade comprising a two-component adhesive formulation according to any one of claims 1 to 11 polymerized by mixing compositions (A) and (B), said polymerized two-component formulation being simultaneously in contact with a first substrate and a second substrate of a wind turbine blade.