A method for producing wind turbine blades, the wind turbine blades produced accordingly, and a resin composition suitable for said production.

Abstract

A resin composition is described, suitable for producing wind turbine blades or any of the aforementioned components by vacuum infusion. The resin composition comprises an epoxy component, an amine component, and a polyfunctional (meth)acrylate component, wherein at least one of the aforementioned components contains acetal and / or ketal functional groups. Furthermore, a method for producing wind turbine blades, nacelles, or any of the aforementioned components, and the corresponding produced wind turbine blades, nacelles, or any of the aforementioned components, are described.

Description

Invention Field

[0001] This invention relates to the field of wind turbine blades, and particularly to resin compositions suitable for methods of producing wind turbine blades or nacelles by means of vacuum infusion, and methods for producing wind turbine blades, nacelles or any of the aforementioned components. Background Technology

[0002] Wind power is considered one of the cleanest and most environmentally friendly energy sources available today, and wind turbines have received increasing attention in order to utilize this energy. A modern wind turbine typically consists of a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture the kinetic energy of the wind and transfer it as rotational energy to rotate the shaft that connects the rotor blades to the gearbox or directly to the generator. The generator then converts the mechanical energy into electrical energy that can be fed into the power grid.

[0003] Various components of wind turbines, such as turbine blades or nacelles, are typically made of composite materials of (glass) fiber-reinforced polymer resins. Commonly used methods for producing such composites include vacuum-assisted resin transfer molding (VARTM), in which liquid or flowable resin is injected into a mold under a vacuum. For this purpose, low-viscosity resins are typically used, which reduces the cycle time for component manufacturing. Furthermore, the recycling and reprocessing of composite materials are becoming increasingly important issues.

[0004] Epoxyamine resins are commonly used as resin starting materials in industry. Their chemical properties are versatile for applications in wind turbine blades and components because of their outstanding mechanical properties, and their physical properties can be tuned to suit vacuum infusion processes that require low viscosity and long pot life, ideally combined with rapid curing. A disadvantage of epoxyamine resins is their reaction enthalpy and its release mechanism. This can lead to very high temperatures in thick components and insulating areas.

[0005] Despite the numerous advantages of ethylene oxide-based resins, challenges exist in the handling, post-treatment, maintenance, and end-of-life of cured structures.

[0006] For example, if geometric deviations exist, they must be accepted; defects such as dry areas or cracks must be removed and reconstructed with specialized resin for post-processing. The same applies to damage occurring during operation. End-of-life disposal is also difficult. Few recycling technologies are available, but those are less suitable for recycling glass-reinforced composite structures because the cost of the recycling process exceeds the value of the recycled materials.

[0007] Therefore, it may be necessary to further improve amine-based resins used in the production of composites of fiber-reinforced polymer resins for wind turbine blades or other components of wind turbines, particularly in terms of reprocessability and recyclability. Invention Overview This need can be met by the subject matter of the independent claims. Advantageous embodiments of the invention are described in the dependent claims.

[0009] According to one aspect of the invention, a resin composition is provided (suitable for the production of wind turbine blades, nacelles or components thereof by means of vacuum infusion) comprising an epoxy component, an amine component and a polyfunctional (meth)acrylate component (containing two or more (meth)acrylate functional groups), wherein at least one of the epoxy component, the amine component and the polyfunctional (meth)acrylate component comprises an acetal and / or a ketal functional group.

[0010] According to a further aspect of the invention, a method for producing a wind turbine blade, nacelle, or any of the aforementioned components is provided, the method comprising applying a resin composition as described herein into a mold by vacuum infusion, particularly vacuum-assisted resin transfer molding, and curing the resin composition.

[0011] According to a further aspect of the invention, wind turbine blades, nacelles, or any of the foregoing components are provided that can be obtained (or acquired) by means of the methods described herein.

[0012] These aspects of the invention are particularly based on the discovery that the combination of acetals / ketals and (meth)acrylates in epoxy-amine resins introduces novel chemical motifs that exhibit interesting synergistic effects. Acetals, along with β-amino esters (obtained by the azira-Michael addition reaction between amines and acrylates), provide dynamic properties, but the combination of both allows for the use of very low levels of acrylates to achieve good solderability or reduce the number of acetal / ketal groups in the network. Recyclability under acidic conditions is also enhanced. This can be achieved through shorter process times or the application of less reactive acetals / ketals in the curing agent.

[0013] The inventors have specifically studied a resin composition containing a ketal moiety in the main chain of a curing agent—the curing agent being based on Recyclamine technology, which uses an acetal or ketal moiety in the main chain to introduce recyclability.

[0014] Furthermore, a portion of the epoxy moiety in the epoxy-amine resin has been replaced by an acrylate, which can react with an amine to generate a β-amino ester via aza-Michael addition, and the acrylate further exhibits a dissociation dynamic mechanism via a retro-aza-Michael reaction, as illustrated in the following exemplary reaction scheme: Where EWG represents an electron-withdrawing group, and R represents any residue.

[0015] Both techniques are known to provide dynamic behavior, but the requirements for their application as infusion resins for blades greatly limit this effect. On the one hand, the high crosslinking density of acetals, and on the other hand, limiting the acrylate content to a low level to maintain mechanical properties and avoid excessive viscosity increases due to the much higher reactivity of acrylates compared to epoxy groups, restrict the achievable dynamic properties.

[0016] In addition to the reverse azira-Michael reaction, the ester groups of acrylic components and acetals can participate in exchange reactions via hydroxyl groups, which are abundant in the network generated by the ring-opening reaction of epoxy groups.

[0017] Surprisingly, a synergistic effect was found when combining these two technologies. However, formulations containing 20% ​​acrylate in the resin portion, along with conventional amine curing agents, offer limited reprocessability, while resin systems based on ketal-containing (AdityaBirla Chemicals' Recyclamine) curing agents with 15% acrylate have proven to exhibit good weldability and reformability. This provides much greater freedom in the formulation of infusion resins and in balancing mechanical, physical, and reactive properties. The acetal or ketal portion can be in the epoxy, acrylate, or amine portion.

[0018] In addition to the advantages mentioned above, this novel resin exhibits excellent adhesion to a variety of substrates, including conventional epoxy amine resins. Invention Details The details of the invention and its other features and advantages will be described below. However, the invention is not limited to the specific description below, but is used for illustrative purposes only.

[0020] It should be noted that features described in connection with one exemplary embodiment or aspect may be combined with any other exemplary embodiment or aspect. In particular, features described in connection with any exemplary embodiment of the resin composition may be combined with any other exemplary embodiment of the resin composition and with any exemplary embodiment of the method of producing a wind turbine blade, nacelle or any of the aforementioned components, and vice versa, unless otherwise expressly stated.

[0021] When referring to a singular term, the use of an indefinite or definite article, such as “a,” “an,” or “the,” also includes the plural form of the term, and vice versa, unless otherwise explicitly stated.

[0022] As used in this article, the word "contains" includes not only the meaning of "containing", "including", or "containing", but also "basically composed of" and "composed of".

[0023] Unless otherwise expressly stated, the expressions “at least partially”, “at least partially” or “at least (a) part” as used herein may refer to at least 5%, in particular at least 10%, in particular at least 15%, in particular at least 20%, in particular at least 25%, in particular at least 30%, in particular at least 35%, in particular at least 40%, in particular at least 45%, in particular at least 50%, in particular at least 55%, in particular at least 60%, in particular at least 65%, in particular at least 70%, in particular at least 75%, in particular at least 80%, in particular at least 85%, in particular at least 90%, in particular at least 95%, in particular at least 98%, and may also refer to 100%.

[0024] In a first aspect, a resin composition is provided. This resin composition is particularly suitable for vacuum infusion methods and is therefore also referred to as an infusion resin. Furthermore, this resin composition is particularly suitable for producing wind turbine blades, nacelles, or any of the foregoing components or any other components of a wind turbine that comprise a composite material containing a (glass) fiber reinforced polymer resin.

[0025] As used herein, the term "composition" can specifically refer to a composition in which the components (ingredients) are close to each other and / or the components are (vigorously) mixed, for example, by using a mixer, agitator, and / or by shaking, thereby forming the composition. In particular, the components of the composition can be uniformly distributed or dispersed throughout the composition. The composition can be, in particular, a semi-solid (paste) or liquid, especially a liquid solution or a semi-solid or liquid suspension.

[0026] As used herein, the term "resin composition" may specifically refer to a composition comprising or consisting primarily of a resin or resin component that may chemically react with some of each other (e.g., polymerization or crosslinking) to cure or harden, which is typically induced by thermal energy (e.g., heating) or electromagnetic radiation.

[0027] The resin composition comprises an epoxy component, an amine component, and a polyfunctional (meth)acrylate component. At least one of the epoxy component, amine component, and polyfunctional (meth)acrylate component comprises acetal and / or ketal functional groups. In other words, the epoxy component (at least a portion thereof), the amine component (at least a portion thereof), and / or the polyfunctional (meth)acrylate component (at least a portion thereof) comprises acetal and / or ketal functional groups. Therefore, any one of the aforementioned components, a combination of any two of the aforementioned components, or all three of the aforementioned components may comprise acetal and / or ketal functional groups. Alternatively, one of the aforementioned components may comprise an acetal functional group and another of the aforementioned components may comprise a ketal functional group, or even one of the aforementioned components may comprise both acetal and ketal functional groups in the same molecule.

[0028] Acetal and ketal functional groups are usually represented by the following chemical formulas: Where R 1 R 2 R 3 and R 4 Each represents an organic (carbon-containing) part independently. As those skilled in the art know, acetals or ketals can be cleaved by hydrolysis under acidic conditions to produce two alcohols (R in the above general formula). 1 -OH and R 2 -OH) and an aldehyde (R in the above general formula of an acetal) 3 -CHO) or a ketone (R in the above general formula of a ketal) 3 -C(=O)-R 4 ).

[0029] The resin composition contains an epoxy component. There are no particular limitations on the epoxy component, and any suitable example conventional in the field of epoxy-amine infusion resins can be used. The epoxy component is characterized in particular by containing one or more epoxy functional groups.

[0030] In one embodiment, at least a portion (or all) of the epoxy component contains acetal and / or ketal functional groups. In particular, it may be sufficient if 25 to 50% of the epoxy component contains acetal and / or ketal functional groups.

[0031] In one embodiment, the epoxy component is selected from glycidyl ethers, glycidyl esters, glycidyl amines, divinylbenzene dioxide, alicyclic epoxides, and combinations thereof.

[0032] In one embodiment, the epoxy component is selected from bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, bisphenol E diglycidyl ether, bisphenol Z diglycidyl ether, bisphenol C diglycidyl ether, bisphenol AP diglycidyl ether, triphenol PA triglycidyl ether, 4,4'-dihydroxydiphenyl diglycidyl ether, 4,4'-dihydroxybenzophenone diglycidyl ether, and hydrogenated forms of the listed substances (versions) and combinations thereof.

[0033] In one embodiment, the epoxy component is selected from butanediol diglycidyl ether, hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, fatty alcohol glycidyl ethers (saturated, unsaturated, C8-C24, straight-chain or branched, single substance or mixture), 2-ethylhexyl glycidyl ether, glycidyl tert-carbonate and similar fatty acid glycidyl esters (saturated, unsaturated, C8-C24, straight-chain or branched, single substance or mixture), epoxidized phenolic varnish, epoxidized cresol varnish, triglycidyl-p-aminophenol, trimethylolpropane triglycidyl ether, diglycidyl ether of cyclohexanediol, and polyoxypropylene. Diglycidyl ether, diglycidyl ether of polyoxyethylene, triglycidyl ether of propoxylated glycerol, monoglycidyl ether of p-tert-butylphenol, diglycidyl hexahydrophthalic acid, phenol glycidyl ether, cashew phenol glycidyl ether, cresol glycidyl ether, resorcinol diglycidyl ether, vanillin-based epoxy resins and their dimers or oligomers, eugenol epoxy resins and their dimers or oligomers, limonene oxide or dioxide, epoxidized sorbitol, epoxidized fatty acids, 2,5-bis(hydroxymethyl)furan diglycidyl ether, difurandiol diglycidyl ether, triglycidyl ether of castor oil, tetraglycidyl ether of m-phenylenediamine, and combinations thereof.

[0034] In one embodiment, the epoxy component is a combination of epoxy components mentioned in this application, particularly the epoxy resin component described above.

[0035] The resin composition also contains an amine component. There are no particular limitations on the amine component, and any suitable example commonly used in the field of epoxy amine impregnation resins can be used. The amine component is characterized in particular by containing one or more amine functional groups.

[0036] In one embodiment, at least a portion (or all) of the amine component comprises acetal and / or ketal functional groups. In particular, it may be advantageous if 50 to 100% of the amine component comprises acetal and / or ketal functional groups.

[0037] In one embodiment, the amine component is selected from aliphatic polyamines, aryl aliphatic polyamines, alicyclic polyamines, alkanolamines, polyether polyamines, and combinations thereof.

[0038] In one embodiment, the amine component, particularly the sterically hindered amine component, is selected from cyclohexylamine, methylcyclohexylamine, dimethylcyclohexylamine, isophorone diamine, cyclohexane diamine, methylcyclohexane diamine, N-aminoethylpiperazine, menthane diamine, 1,3-bis(aminomethyl)cyclohexane, diaminodicyclohexylmethane, diaminodimethyldicyclohexylmethane, N-(3-aminopropyl)cyclohexylamine, and combinations thereof.

[0039] In one embodiment, the amine component is selected from diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine, diethylaminopropylamine, alkane diamines (propylenediamine, butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanedanediamine, undecanediamine, dodecanediamine and longer-chain diamines and isomers, such as neopentanediamine, isobutanediamine) and combinations thereof.

[0040] In one embodiment, the amine component is selected from polyamide amines, polyamide imidazoles, polyaminoimidazolium, Mannich basic amines, phenalkamines, and combinations thereof.

[0041] In one embodiment, the amine component is selected from amine-terminated polyethylene glycol, amine-terminated polypropylene glycol, amine-terminated polybutane glycol, amine-terminated mixed polyalkylene glycols, dioxadodecanediamine, amine-terminated glyceryl polyethylene glycol, and combinations thereof.

[0042] In one embodiment, the amine component is a combination of the amine components mentioned in this application, particularly the aforementioned amine components.

[0043] The resin composition also comprises a polyfunctional (meth)acrylate component. The polyfunctional (meth)acrylate component is characterized in that it contains two or more (meth)acrylate functional groups. A polyfunctional acrylate component, i.e., containing two or more acrylate functional groups, is preferred, but a polyfunctional methacrylate component, i.e., containing two or more methacrylate functional groups, can also be used. A mixed polyfunctional (meth)acrylate component containing one or more acrylate functional groups and one or more methacrylate functional groups may also be used.

[0044] The term “(meth)acrylate” encompasses acrylates and / or methacrylates. As used herein, the terms “acrylate” and “methacrylate” correspond to their generally accepted meanings. Acrylates may be represented by the general formula “H₂C=CH-C(=O)-”, and methacrylates may be represented by the general formula “H₂C=C(CH₃)-C(=O)-”. Acrylates may also encompass itaconic acid esters.

[0045] In one embodiment, the multifunctional (meth)acrylate component comprises two, three, four or more (meth)acrylate functional groups.

[0046] In one embodiment, at least a portion (or all) of the polyfunctional (meth)acrylate component comprises acetal and / or ketal functional groups. In particular, it may be sufficient if 50 to 100% of the polyfunctional (meth)acrylate component comprises acetal and / or ketal functional groups.

[0047] In one embodiment, the polyfunctional (meth)acrylate component is selected from diol diacrylate, butanediol diacrylate, dipropylene glycol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A diglycidyl ether diacrylate, trimethylolpropane triacrylate, and combinations thereof.

[0048] In one embodiment, the (meth)acrylate component is selected from methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, pentyl acrylate, isoamyl acrylate, neopentyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate and longer-chain alkyl acrylates and their isomers, hydroxypropyl acrylate, hydroxyethyl acrylate, 2-phenoxyethyl acrylate, tert-butylcyclohexyl acrylate, 3-methyl-1,5-pentanediol diacrylate, tricyclodecane methanol acrylate, caprolactone acrylate, cyclotrimethylolpropane methyl acetal acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, and isobornyl.

[0049] In one embodiment, the (meth)acrylate component is selected from glycol diacrylate, butanediol diacrylate, neopentyl glycol diacrylate, decanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, tricyclodecanediethanol diacrylate, and urethaneacrylates.

[0050] In one embodiment, (meth)acrylate is a combination of (meth)acrylates mentioned in this application.

[0051] In one embodiment, the (meth)acrylate is an epoxy acrylate. In another embodiment, the (meth)acrylate is an acrylated epoxy component derived from the epoxy component mentioned in this application.

[0052] In one embodiment, the (meth)acrylate component is selected from trimethylolpropane triacrylate, triglyceride triacrylate, tri(2-hydroxyethyl)isocyanurate triacrylate, soybean oil epoxy acrylate, dipentaerythritol hexaacrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and pentaerythritol tetraacrylate.

[0053] In one embodiment, the (meth)acrylate component is a combination of the (meth)acrylate components mentioned in this application, particularly the aforementioned (meth)acrylate components.

[0054] In one embodiment, the epoxy component and / or amine component and / or (meth)acrylate component are provided and / or present in the presence or absence of a catalyst, such as, but not limited to, imidazole-based catalysts, tertiary amines, metal and metal salt catalysts, organometallic catalysts, enzyme and protein catalysts, and combinations thereof.

[0055] In one embodiment, the resin composition comprises at least one catalyst selected from imidazole-based catalysts, tertiary amines, metal and metal salt catalysts, organometallic catalysts, enzyme and protein catalysts, and combinations thereof.

[0056] In one embodiment, the epoxy component and / or amine component and / or (meth)acrylate component are provided and / or present in the presence of additives, such as, but not limited to, wetting agents, coupling agents, nano and micro fillers, defoamers, degassing agents, and combinations thereof.

[0057] In one embodiment, the resin composition comprises at least one additive, which is a wetting agent, a coupling agent, a nano- or micro-sized filler, a defoamer, or a degassing agent. The at least one additive may be a combination of the above-mentioned additives.

[0058] In one embodiment, the molar ratio of the polyfunctional (meth)acrylate component ranges from 10 to 50 mol%, and the molar ratio of the epoxy component ranges from 50 to 90 mol%, each based on 100 mol% of the amine component. In other words, for every 100 mol% of the amine component, the resin composition may contain 50 to 90 mol% of the epoxy component and 10 to 50 mol% of the polyfunctional (meth)acrylate component. The total amount of the epoxy component and the polyfunctional (meth)acrylate component may specifically be 100 mol%. An excess of the amine component may also be present compared to the total amount of the epoxy component and the polyfunctional (meth)acrylate component. For example, the composition may also contain 100 to 200 mol% of the amine component, 50 to 90 mol% of the epoxy component, and 10 to 50 mol% of the polyfunctional (meth)acrylate component. However, it is advantageously unnecessary to have an excess of the amine component compared to the total amount of the epoxy component and the polyfunctional (meth)acrylate component.

[0059] In one embodiment, the molar ratio of the polyfunctional (meth)acrylate component to the epoxy component is in the range of 1:8 to 1:2, particularly in the range of 1:5 to 1:2.

[0060] The resin composition according to the first aspect can be advantageously used in the method according to the second aspect as described below.

[0061] In a second aspect, a method for producing wind turbine blades, nacelles, or any of the aforementioned components is provided.

[0062] In this method, the resin composition as described herein is applied, particularly injected, into a mold by vacuum infusion. In the context of this specification, the term "vacuum infusion" may specifically refer to a molding technique in which a liquid or flowable resin is injected into a mold under an applied vacuum. In particular, vacuum-assisted resin transfer molding (VARTM) may be used. The infused resin may be, in particular, a liquid or flowable composition comprising components that can react with each other to form a cured or hardened product, typically at least two different types of components.

[0063] The mold into which the resin composition is applied typically forms a cavity, and is therefore also called a mold cavity. The mold can be adapted to the contours of the turbine blade, nacelle, or any of the aforementioned components to be produced.

[0064] In one embodiment, the step of curing the resin composition includes heating the resin composition to a temperature in the range of 60 to 150°C, particularly 70 to 120°C.

[0065] In one embodiment, the method further includes removing the mold after curing the resin composition, thereby obtaining the produced wind turbine blade, nacelle, or component thereof.

[0066] In a further aspect, wind turbine blades, nacelles, or any of the aforementioned components can be obtained or acquired by means of the methods described above.

[0067] Although the invention has been described in detail with reference to specific embodiments and examples, it should be understood that the invention is not limited thereto, and various changes and modifications are possible without departing from the scope of the invention.

Claims

1. A resin composition comprising: Epoxy components; Amine components; Multifunctional (meth)acrylate components, The epoxy component, the amine component, and the polyfunctional (meth)acrylate component contain at least one acetal and / or ketal functional groups.

2. The resin composition of claim 1, wherein at least a portion of the epoxy component comprises acetal and / or ketal functional groups, particularly wherein 25 to 50% of the epoxy component comprises acetal and / or ketal functional groups.

3. The resin composition according to any one of the preceding claims, wherein the epoxy component is selected from glycidyl ethers, glycidyl esters, glycidyl amines, divinylbenzene dioxide, alicyclic epoxides, and combinations thereof.

4. The resin composition according to any one of the preceding claims, wherein at least a portion of the amine component comprises acetal and / or ketal functional groups, particularly wherein 50 to 100% of the amine component comprises acetal and / or ketal functional groups.

5. The resin composition according to any one of the preceding claims, wherein the amine component is selected from aliphatic polyamines, aryl aliphatic polyamines, alicyclic polyamines, alkanolamines, polyether polyamines, and combinations thereof.

6. The resin composition according to any one of the preceding claims, wherein at least a portion of the polyfunctional (meth)acrylate component comprises acetal and / or ketal functional groups, particularly wherein 50 to 100% of the polyfunctional (meth)acrylate component comprises acetal and / or ketal functional groups.

7. The resin composition of any of the preceding claims, wherein the polyfunctional (meth)acrylate component comprises two, three, four or more (meth)acrylate functional groups.

8. The resin composition according to any one of the preceding claims, wherein the polyfunctional (meth)acrylate component is selected from diethylene glycol diacrylate, butanediol diacrylate, dipropylene glycol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A diglycidyl ether diacrylate, trimethylolpropane triacrylate, and combinations thereof.

9. The resin composition according to any one of the preceding claims, wherein the molar ratio of the polyfunctional (meth)acrylate component is in the range of 10 to 50 mol%, and the molar ratio of the epoxy component is in the range of 50 to 90 mol%, each based on 100 mol% of amine component.

10. A method for producing a wind turbine blade, nacelle, or any of the aforementioned components, the method comprising: The resin composition according to any one of the preceding claims is applied into a mold by vacuum infusion, particularly by vacuum-assisted resin transfer molding. The resin composition is cured.

11. The method of claim 10, wherein the step of curing the resin composition comprises heating the resin composition to a temperature in the range of 60 to 150°C, particularly 70 to 120°C.

12. The method of any one of claims 10 to 11, wherein the method further comprises removing the mold after curing the resin composition.

13. A wind turbine blade, nacelle, or any of the aforementioned components, which can be obtained by the method according to any one of claims 10 to 12.

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