Coating system

Abstract

The present invention relates to a coating system comprising at least two layers A and B wherein said layers A and B are adjacent, and wherein layer A comprises: (A) a bond coat composition comprising: (i) a first component comprising at least one polyol resin; and (ii) a second component comprising an isocyanate compound; and wherein layer B comprises: (B) a leading edge protection (LEP) coating composition comprising: a) a first component comprising at least one polymer selected from the group consisting of polyols, polyaspartic esters, polyether aspartic esters, and mixtures thereof; and b) a second component comprising at least one polyisocyanate curing agent.

Description

Technical Field

[0001] The present invention relates to a coating system, in particular to a coating system for a wind turbine blade, in particular a leading edge of a wind turbine blade. The coating system comprises a tiecoat composition and a leading edge protection (LEP) coating composition. The present invention also relates to a substrate, in particular a wind turbine blade, coated with the coating system, and to the use of the coating system in coating a substrate such as a wind turbine blade. Background Art

[0002] A common challenge in the wind turbine industry is the wear and erosion of wind turbine blades due to the high speed at the blade tips and the impact of raindrops and particulate matter such as dust or sand. Rotating arm rain erosion test (RET) rigs are often used to test durability.

[0003] Leading Edge Protection (LEP) is used to protect the highest rotation speeds (usually more than 300km hr -1 ) of the blade peripheral part (leading edge). A typical coating system for LEP includes at least one basecoat (e.g. polyurethane or polyaspartic acid) and a LEP coating. In some cases, an additional topcoat is applied on top of the LEP coating. Adhesion is crucial in obtaining good RET performance, especially for leading edge protection. However, LEP often fails because the LEP coating peels off from the substrate (glass fiber reinforced plastic, also called glass fiber reinforced polymer, GRP), the filler or the basecoat (usually polyurethane or polyaspartic acid).

[0004] It is therefore an object of the present invention to provide an improved coating system having good corrosion resistance and adhesion to at least one of a substrate, a filler or a primer. It is also desirable to provide a coating system having good storage stability and / or shelf life. The inventors have unexpectedly discovered that a system comprising a specific tie layer and a LEP coating provides an attractive solution. Summary of the invention

[0005] Thus, in a first aspect, the present invention provides a coating system comprising at least two layers, A and B, wherein said layer A and layer B are adjacent, and wherein layer A comprises:

[0006] (A) a bonding layer composition comprising:

[0007] (i) a first component comprising at least one polyol resin; and

[0008] (ii) a second component comprising an isocyanate compound; and

[0009] Layer B includes:

[0010] (B) A leading edge protection (LEP) coating composition comprising:

[0011] a) a first component comprising at least one polymer selected from the group consisting of polyols, polyaspartates, polyether aspartates, and mixtures thereof; and

[0012] b) A second component comprising at least one polyisocyanate curing agent.

[0013] In a second aspect, the present invention provides a coating system comprising at least two layers, A and B, wherein the layers A and B are adjacent, and wherein the layer A comprises:

[0014] (A) a bonding layer composition comprising:

[0015] (i) a first component comprising at least one polyol resin; and

[0016] (ii) a second component comprising an isocyanate compound,

[0017] wherein the first and second components have been mixed and cured; and

[0018] Layer B includes:

[0019] (B) A leading edge protection (LEP) coating composition comprising:

[0020] a) a first component comprising at least one polymer selected from the group consisting of polyols, polyaspartates, polyether aspartates, and mixtures thereof; and

[0021] b) a second component comprising at least one polyisocyanate curing agent,

[0022] The first and second components are mixed and cured.

[0023] It is preferred that the polyol resin is an epoxy resin, such as bisphenol A epoxy resin, wherein the epoxy resin as the polyol resin (i) in (A) has a number average molecular weight (Mn) of at least 3000 g mol -1 , preferably at least 3500 g mol -1 ;

[0024] Or the polyol resin is a phenolic resin, preferably a novolac resin.

[0025] In a third aspect, the present invention provides a substrate at least partially coated with a coating system as defined above.

[0026] In another aspect, the present invention provides the use of a coating system as defined hereinbefore for coating at least a portion of a substrate, wherein the substrate is preferably a wind turbine blade, more preferably a leading edge of a wind turbine blade.

[0027] In another aspect, the present invention provides a method for coating at least a portion of a substrate with a coating system as defined above, the method comprising applying a tie layer composition (A) to the surface of the substrate and curing the composition (A), and then applying a LEP coating composition (B) directly on the composition (A) and curing the composition (B).

[0028] definition

[0029] As used herein, leading edge protection (LEP) coatings are coatings applied to protect the highest rotational speeds (typically in excess of 300 km hr) -1 ) of the blade peripheral portion (leading edge). Primer, mid-coat, top coat and tie coat are all terms well known in the art.

[0030] "Epoxy resin" refers to any polymer containing one or more epoxide moieties.

[0031] As used herein, equivalent weight refers to the mass of a reactive compound having the number of reactive groups equivalent to 1 mole, in grams. For epoxy-based adhesives, equivalent weight refers to the epoxy equivalent weight (EEW). Thus, the contribution of each epoxy adhesive or other epoxy-functional component to the epoxy equivalent in the composition is defined as the number of grams of epoxy compound divided by the epoxy equivalent weight of the epoxy compound.

[0032] When quoting the "molecular weight" of a particular component, we mean the theoretical value of the molecular weight of an ideal molecule. This is usually applied to small molecules.

[0033] When quoting the "number average molecular weight (M)" of a particular component (usually a polymer component), n )”, we mean the total weight divided by the total number of molecules. n is a value obtained analytically, for example, by end group analysis or gel permeation chromatography (GPC).

[0034] In the context of the present invention, "curing" refers to the process of obtaining a solid layer of a coating system from a liquid component. Curing can occur, for example, by chemical reaction and / or by evaporation of a solvent. It should be understood that the curing reaction may not always be complete, for example, after "curing" occurs, unreacted functional groups, such as isocyanate groups, may remain. Therefore, "curing", "curing" or "curing" includes partial curing and fully curing situations. DETAILED DESCRIPTION

[0035] The present invention relates to a coating system comprising at least two layers, A and B, wherein the layers A and B are adjacent, and wherein the layer A comprises a tie layer composition (A), and the layer B comprises a leading edge protection (LEP) coating composition (B). The coating composition comprises at least two layers, so that the layers A and B are different.

[0036] Adhesive layer composition (A)

[0037] The tie layer composition (A) forms layer A of the coating system. Therefore, layer A can be referred to as a tie layer. In the context of the present invention, the term "tie layer" refers to a layer of a coating system that acts as a bridge between, for example, a substrate or a primer or a base coat and an adjacent LEP coating. Therefore, it should be understood that the tie layer A does not form the outermost layer of the coating system. Therefore, similarly, the tie layer composition (A) of the present invention is not used as the outermost layer composition in a coating system.

[0038] The tie layer composition (A) comprises a first component (i) comprising at least one polyol resin and a second component (ii) comprising at least one isocyanate compound. In one embodiment of the present invention, the first component and the second component have been mixed and cured.

[0039] First (polyol) component (i)

[0040] The first component comprises at least one polyol resin. The polyol resin is a hydroxyl functional compound (i.e., a compound containing hydroxyl functional groups that can be masked as epoxy groups). Preferably, the polyol is a high molecular weight polyol, more preferably containing aromatic segments in the backbone of the polymer structure. Preferably, the M of the polyol is n At least 1500 g mol -1 , more preferably at least 2000 g mol -1 , even more preferably at least 3500 g mol -1 Values ​​up to 20,000 g / mol are possible, such as 15,000 g / mol.

[0041] Although it is within the scope of the present invention to have more than one polyol resin, it is preferred to use only a single polyol resin.

[0042] In one aspect, the polyol resin comprises a bisphenol type compound. Examples of such bisphenol type compounds are diglycidyl ether of bisphenol A (BADGE) or diglycidyl ether of bisphenol F, which resins are generally referred to as epoxy resins. Bisphenol A is preferred. Preferably, the resin is solid under ambient conditions. The preferred epoxy resin is epoxy resin type 8 or type 9, most preferably type 9. Preferably, M n At least 1500 g mol -1, more preferably at least 2000 g mol -1 , more preferably at least 3000 g mol -1 .

[0043] Epoxy resins are usually characterized by their epoxide equivalent weight (EEW). The (solid) resin ideally has 1100-7000 g eq. -1 EEW, preferably 2000-5000g eq -1 The epoxy resins suitable for application in the present invention generally have a hydroxyl equivalent weight (OHEW) of 305-293.

[0044] The epoxy resin (eg, solid epoxy resin) may have a softening point of 100-180°C, preferably 120-160°C, such as 130-150°C, when measured according to ASTM D 3104.

[0045] The kinematic viscosity of the epoxy resin (eg, solid epoxy resin) as a solution having a solid content of 40% by weight in diethylene glycol monobutyl ether is 1000-10000 cSt, preferably 1000-8000 cSt, when measured according to ASTM D 445.

[0046] Examples of suitable commercially available bisphenol A epoxy resins are YD-017H, KD-2119, YD-019, YD-019K, YP-50, YP-55 and YP-70 from Kukdo Chemical Co., DER 668-20, DER 669-20 and DER 669E from Olin.

[0047] In another aspect, the polyol resin may include a phenolic resin synthesized from phenol (e.g., unsubstituted phenol or vinylphenol) and / or its derivatives (e.g., but not limited to, resorcinol, meta-cresol, 2,3-xylenol, cardanol, and cardanol diphenol and aldehyde). Preferably, in this embodiment, the resin is a phenolic resin (novolak resin). The novolac resin may also be a mixture of at least a partial reaction of 1) a carbamic acid resin derived from n-butyl carbamate and formaldehyde and 2) a phenol novolac derived from phenol and formaldehyde. A suitable mixture of a carbamic acid resin and a phenol novolac is available from Allnex as Alnovol PN760.

[0048] Novolac resins generally have a carbon content of at least 500 g mol -1 and a softening point of 90-130°C. Examples of suitable commercially available novolac resins include Alnovol PN320 / PAST from Allnex and those available from SBHPP. Particularly suitable novolac resins include high molecular weight resins such as Mn >1000g mol -1 Those.

[0049] The polyol resins of the present invention can be cured by reaction with a curing agent reactive toward hydroxyl groups (OH groups). "Curable" means that the resin contains reactive OH groups capable of reacting with isocyanate compounds and forming a cured or crosslinked polymer.

[0050] The polyol resin is generally present in an amount of 10 to 95 wt % relative to the total weight of the first (polyol) component (i). Preferably, the polyol resin forms more than 90 wt % (dry) relative to the dry weight (i.e. excluding solvent) of the first (polyol) component (i).

[0051] The polyol resin is generally present in an amount of 5 to 50 wt %, preferably 10 to 30 wt %, relative to the total weight of the tie layer composition (A). Preferably, the polyol resin forms 10 to 90 wt % (dry), more preferably 30 to 80 wt %, for example 60-75 wt % (dry), relative to the dry weight (i.e. excluding solvent) of the tie layer composition (A).

[0052] When more than one polyol resin is present, it is understood that these figures refer to the total amount of all polyol resins present in the tie layer composition (A).

[0053] Second component (ii): isocyanate compound

[0054] The isocyanate compound may be any suitable compound comprising at least one isocyanate functional group.A single isocyanate compound or a mixture of more than one isocyanate compound may be used.

[0055] The number of isocyanate groups per molecule is easily determined by the isocyanate content and the M of the corresponding polyisocyanate. n The isocyanate content (in % by weight) can be determined, for example, in accordance with DIN EN ISO 11909 by reacting a corresponding sample with an excess of dibutylamine and back-titrifying the excess with hydrochloric acid against bromophenol blue.

[0056] In a preferred embodiment, the isocyanate compound comprises, for example consists of, a polyisocyanate.Preferred polyisocyanates are solvent-free and substantially free of isocyanate monomers, for example containing less than 0.5% isocyanate monomers as measured according to DIN EN ISO 10283.

[0057] In the context of the present invention, aliphatic, cycloaliphatic or aromatic polyisocyanates can be used, such as hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate, 1,5-pentamethylene diisocyanate (PDI), 4,4'-diisocyanatodicyclohexylmethane (HDI), 12 The invention also includes polyisocyanates containing biuret, allophanate, urethane or isocyanurate groups.

[0058] Preferably, the polyisocyanate is aromatic or aliphatic or a combination thereof. The aliphatic isocyanate is preferably silane functional or a HDI trimer.

[0059] Most preferably, the polyisocyanate comprises (eg consists of) an aromatic polyisocyanate, such as TDI or MDI.

[0060] The polyisocyanate may be in any form including, but not limited to, dimer, trimer, isocyanurate, adduct, polymer and prepolymer isocyanates.

[0061] The isocyanate (NCO) content of the polyisocyanate is preferably 5 to 35 wt % in the supplied form.

[0062] The molecular weight of the polyisocyanate is preferably 200 to 3,000 g mol -1 .

[0063] The functionality of the polyisocyanate (ie the number of isocyanate groups present per molecule) may be in the range of 2 to 10, for example 2 to 5.

[0064] Polyisocyanates useful in the present invention are commercially available. Commercial suppliers include Covestro, BASF, Asahi Kasei, Wanhua and Vencorex, and suitable polyisocyanates are sold under trade names such as Desmodur, Duranate, Tolonate, Wannate and Basonate.

[0065] The isocyanate compound in component (ii) is preferably present in the bonding layer composition (A) of the present invention in a range of 2 to 50 wt %, more preferably 10 to 45 wt %, such as 12 to 40 wt %, for example 15 to 35 wt %, relative to the total weight of the bonding layer composition (A). Preferably, the isocyanate compound forms 10-90 wt % (dry), more preferably 20-80 wt % (dry), even more preferably 30 to 60 wt % (dry), relative to the dry weight (i.e. excluding solvent) of the bonding layer composition (A).

[0066] Preferably, the isocyanate comprises more than 90 wt% (dry) relative to the dry weight (ie excluding solvent) of component (ii) of the tie layer composition.

[0067] It will be appreciated that when more than one isocyanate compound is present, the wt% ranges cited above relate to the total amount of all isocyanate compounds employed. In one embodiment, a single isocyanate compound is used. In an alternative embodiment, a mixture of two or more isocyanate compounds is used.

[0068] Based on the mole number (or functional group number) of the total bonding layer composition on the solid (i.e., excluding solvent), the ratio of NCO to amine and hydroxyl (NH+OH) is preferably 0.4-1.1, preferably 0.6-1.0, most preferably 0.7-0.9, such as 0.8. Based on the mole number (or functional group number) of the total bonding layer composition on the solid (i.e., excluding solvent), the ratio of NCO to hydroxyl (OH) is preferably 0.4-1.1, preferably 0.6-1.0, most preferably 0.7-0.9, such as 0.8. These ratios are particularly preferred where the first (polyol) component (i) is bisphenol A.

[0069] Other components

[0070] The tie layer composition (A) of the present invention may also contain other substances commonly used in coating formulations, such as fillers, pigments, matting agents, solvents and additives such as waxes, dyes, dispersants, wetting agents, defoamers, surfactants, tackifiers, light stabilizers, dewatering agents and thixotropic agents.

[0071] In a specific embodiment, the tie layer composition (A) comprises a tackifier.

[0072] Examples of suitable adhesion promoters include alkoxysilanes such as those known under the trade name Dynasylan from Evonik, for example Dynasylan AMEO and Dynasylan 1189, and those known as Silquest from Momentive, such as A1524 (similar to VPS 2101, 3-ureidopropyltrimethoxysilane from Evonik), and NCO-alkoxysilane hybrids such as Silquest from Covestro. 2873. Dynasylan GLYMO, Dynasylan GLYE, Dynasylan AMMO and Dynasylan DAMO may also be used.

[0073] Examples of extenders are minerals such as dolomite, quartz, barite, silica, wollastonite, talc, mica, kaolin and feldspar; synthetic inorganic compounds such as calcium carbonate, barium sulfate, polymer microspheres and inorganic microspheres. Preferably, the tie coat composition / layer does not contain any extender.

[0074] Pigments of interest include organic pigments and inorganic pigments.

[0075] Examples of suitable solvents and diluents include solvents that are non-reactive toward isocyanate groups. Suitable solvents are esters (e.g. ethyl acetate, isopropyl acetate, n-butyl acetate, tert-butyl acetate, methyl glycol acetate (2-methoxyethyl acetate), ethyl glycol acetate (2-ethoxyethyl acetate), butyl glycol acetate (2-butoxyethanol acetate)), n-butanol, isobutanol, tert-butanol, 2-butanol, benzyl alcohol, isopropanol, n-propanol, 2-propanol, 1-methoxy-2-propyl acetate (PMA glycol ether), ethers (e.g. tetrahydrofuran, dioxane), ketones (e.g. acetone, 2-butanone (methyl ethyl ketone), 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), 2-hexanone, 5-methyl-2-hexanone, 2-heptanone, cyclohexanone, cyclopentanone), hydrocarbons, aromatic hydrocarbons (e.g. benzene, toluene, xylene or ethylbenzene), halogenated hydrocarbons (e.g. chlorobenzene, dichloromethane, trichloromonofluoroethane, p-chlorotrifluorobenzoate) and mixtures of the abovementioned solvents. Preferred solvents are esters such as ethyl acetate, n-butyl acetate, tert-butyl acetate, 1-methoxy-2-propyl acetate and xylene, and ketones such as methyl isobutyl ketone and methyl ethyl ketone.

[0076] The solvent preferably accounts for 20 to 90wt% of the entirety of the adhesive layer composition (A). It should be understood that the wt% range of the solvent is relative to the adhesive layer composition (A) before curing (i.e. before the coating is cured and dried). Any pigment preferably accounts for 1 to 30wt% of the entirety of the adhesive layer composition (A), for example 15 to 25wt%. Relative to the total weight of the adhesive layer composition (A), the total amount of additives usually accounts for less than 10wt%. Relative to the total weight of the adhesive layer composition (A), the compatibilizer usually preferably accounts for 0-40wt%.

[0077] Preferably, any compatibilizers and additives are added to the polyol resin component (i).Pigments may be added to either or both of components (i) or (ii).

[0078] Leading edge protection (LEP) coating composition (B)

[0079] In the context of the present invention, the term "LEP coating composition" (B) refers to a composition that forms layer B of the coating system and is applied adjacent to the tie layer composition (A). It should be understood that the LEP layer B is the outer layer relative to the tie layer. The LEP layer (B) most often forms the outermost layer of the coating system as a whole, but sometimes the LEP layer (B) can be coated with another top coating. Layer B can be called a LEP layer.

[0080] The LEP coating composition of the present invention comprises a first component a), which comprises at least one polymer selected from the group consisting of polyols, polyaspartates, polyether aspartates and mixtures thereof; and a second component b), which comprises at least one polyisocyanate curing agent. In one embodiment of the present invention, the first component and the second component have been mixed and cured.

[0081] First component a)

[0082] The first component a) of the LEP coating composition (B) comprises at least one polymer selected from the group consisting of polyols, polyaspartates, polyether aspartates and mixtures thereof.

[0083] Examples of suitable polyols are polyester polyols, polyacrylic polyols, polyether polyols and polycarbonate polyols.Preferably the first component is not an epoxy resin.

[0084] "Polycarbonate polyol" refers to any polycarbonate polymer containing two or more hydroxyl moieties. In all embodiments of the present invention, it is preferred that the polycarbonate polyol is a diol, i.e., contains two hydroxyl functional groups. More preferably, the two hydroxyl functional groups are terminal groups on the polymer chain, i.e., one at each end of the polymer chain.

[0085] Preferably, the polycarbonate polyol comprises repeating units having the following structure:

[0086]

[0087] in

[0088] R is selected from a linear or branched chain C 1-20 Alkyl, C 3-12 Cycloalkyl and optionally substituted C 6-20 A group consisting of aryl groups; and

[0089] n is an integer of 2-50.

[0090] Preferably, R is a linear or branched C 1-20 Alkyl. The term "alkyl" is intended to include straight or branched chain alkyl groups, such as propyl, butyl, pentyl and hexyl. It should be understood that "alkyl" in the context of polycarbonate is divalent and may therefore also be referred to as "alkylene". Particularly preferred alkyl groups are pentyl and hexyl. In a particularly preferred embodiment, R is hexyl. In all embodiments, the alkyl group is preferably straight chain.

[0091] In one embodiment, there is only a single (i.e., one type) repeating unit. In an alternative embodiment, there are more than one (e.g., two) different repeating units. If there are different repeating units, they can have a random distribution or a regular distribution in the polycarbonate polyol. It should be understood that when there are more than one repeating unit, these repeating units will contain different R groups. In a preferred embodiment, there are two repeating units, the first R is a pentyl, and the second R is a hexyl.

[0092] Particularly preferred cycloalkyl groups include cyclopentyl and cyclohexyl.

[0093] Examples of the substituted aryl group include aryl groups substituted with at least one substituent selected from halogen, alkyl groups having 1 to 8 carbon atoms, acyl groups or nitro groups. Particularly preferred aryl groups include substituted and unsubstituted phenyl, benzyl, phenylalkyl or naphthyl groups.

[0094] Preferably R does not contain hydroxyl functionality.

[0095] Preferably, n is an integer in the range of 2 to 25, such as 2 to 20, for example 2 to 15.

[0096] The functionality of the polycarbonate polymer (ie the number of hydroxyl groups present per molecule) may range from 2 to 10. Preferably, the functionality is 2.

[0097] The polycarbonate polyols of the present invention preferably have a hydroxyl number of 50 to 250, such as 60 to 120 mg KOH / g.

[0098] The viscosity of the polycarbonate polyol at 40° C. may range from 10 mPa·s to 10000 mPa·s, such as 50 mPa·s to 5000 mPa·s, and in particular from 300 mPa·s to 4000 mPa·s.

[0099] Preferably, the polycarbonate polyol is amorphous.

[0100] The softening point of the polycarbonate polyol is preferably below 0°C.

[0101] The polycarbonates used in the present invention are commercially available. Commercial suppliers include Bayer, UBE and Asahi Kasei, and suitable polycarbonates (i) are sold under trade names such as Duranol, Eternacol and Desmophen. Specific examples of suitable commercially available polycarbonates are Duranol T5651, Desmophen C1100, Demophen C XP 2716, Eternacoll PH-100 and Eternacol PH-50.

[0102] "Polyacrylic polyol" refers to any polyol prepared from two or more (meth)acrylate monomers and / or (meth)acrylamide monomers, and it may also contain vinyl monomers. In addition, the polyacrylic polyol contains at least two hydroxyl functional groups.

[0103] The polyacrylic polyol is not particularly limited but may be any polyacrylic polyol reactive with polyisocyanate, and examples thereof may include compounds obtained by polymerizing a mixture of unsaturated monomers selected from unsaturated monomers containing a hydroxyl group, unsaturated monomers containing an acidic group, unsaturated monomers containing an amine group, and other unsaturated monomers.

[0104] The above-mentioned hydroxyl group-containing unsaturated monomer is not particularly limited, and examples thereof may include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, Placcel FM-1 (manufactured by Daicel Chemical Industries; ε-caprolactone-modified hydroxyethyl methacrylate), polyethylene glycol monoacrylate or monomethacrylate, and polypropylene glycol monoacrylate or monomethacrylate.

[0105] The above-mentioned unsaturated monomer containing an acidic group is not particularly limited, and examples thereof may include carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, and maleic acid.

[0106] The above-mentioned other unsaturated monomers are not particularly limited, and examples thereof may include acrylic monomers containing an ester group, such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, ethylhexyl acrylate or lauryl acrylate or methacrylate; vinyl alcohol ester type monomers, such as esters of carboxylic acids such as acetic acid and propionic acid with vinyl alcohol; unsaturated hydrocarbon monomers, such as styrene, α-methylstyrene, vinylnaphthalene, butadiene and isoprene; nitrile type monomers, such as acrylonitrile and methacrylonitrile; and acrylamide type monomers, such as acrylamide, methacrylamide, N-hydroxymethyl acrylamide, N,N-dimethylacrylamide and diacetone acrylamide.

[0107] In one embodiment, the polyacrylic acid polyol is a polyacrylic acid polyol comprising the following repeating units:

[0108]

[0109] Where R 1 and R 2 may be the same or different and are each independently selected from hydrogen, a linear or branched chain C 1-20 Alkyl, linear or branched hydroxyl C 1-20 Alkyl, C 3-12 Cycloalkyl and optionally substituted C 6-20 A group consisting of aryl groups; and

[0110] m is an integer of 2-50.

[0111] Preferably, R 1 and R 2 Each is independently hydrogen, a straight or branched chain C 1-20 Alkyl, or straight chain or branched hydroxyl C 1-20 Alkyl. The term "alkyl" is intended to include straight or branched chain alkyl groups such as methyl, ethyl, propyl, butyl, pentyl and hexyl.

[0112] Preferably, R 1 is hydrogen or C 1-6 An alkyl group, such as a methyl group.

[0113] Preferably, R 1 It is hydrogen, C 1-6 Alkyl or hydroxyl C 1-6 alkyl.

[0114] Particularly preferred cycloalkyl groups include cyclopentyl and cyclohexyl.

[0115] Examples of substituted aryl groups include substituted aryl groups substituted with at least one selected from halogen, C 1-8 Aryl substituted with a substituent in an alkyl group, an acyl group or a nitro group. Particularly preferred aryl groups include substituted and unsubstituted phenyl, benzyl, phenylalkyl or naphthyl.

[0116] Preferably, m is an integer in the range of 2 to 25, such as 2 to 20, for example 2 to 15.

[0117] The repeating units and their preferred embodiments presented above are also applicable to the case where the polyacrylic polyol contains (meth)acrylamide monomers. In this embodiment, it should be understood that OR in the repeating unit 2 Will be changed to NHR 2 In addition, the repeating units and their preferred embodiments presented above are also applicable to the case where the polyacrylic polyol comprises a vinyl alcohol ester type monomer. In such an embodiment, it should be understood that -(C=O)-OR 2 The group will be changed to simply R 2 Group.

[0118] In one embodiment, only a single (i.e., one type) repeating unit is present. In an alternative embodiment, more than one (e.g., two) different repeating units are present. If different repeating units are present, they may have a random distribution or a regular distribution in the polyacrylic acid polyol. It should be understood that when more than one repeating unit is present, these repeating units will be present in R 1 and R 2 is different in at least one of the.

[0119] M of polyacrylic acid polyol n Preferably 200 to 20,000 g mol -1 .

[0120] The functionality of the polyacrylic polyol, ie the number of hydroxyl groups present per molecule, may range from 2 to 10. The polyacrylic polyol of the present invention preferably has a hydroxyl number of 50-250 mg KOH / g, such as 75-180 mg KOH / g, calculated as solids.

[0121] The viscosity of the polyacrylic polyol at 23° C. may range from 10 mPa·s to 20,000 mPa·s, such as from 100 mPa·s to 15,000 mPa·s, and in particular from 500 mPa·s to 12,000 mPa·s. The viscosity may be measured based on pure polyacrylic polyol or polyacrylate polyol in solution. Preferably, the viscosity of the polyacrylic polyol in butyl acetate is measured, such as 50-100 wt % in butyl acetate, for example 75 wt % of the polyacrylic polyol in butyl acetate.

[0122] Polyacrylic acid polyols for use in the present invention are commercially available. Commercial suppliers include Allnex, Arkema, Yoo-Point, Cytec, Covestro and Nuplex. Suitable polyacrylic acid polyols are sold under trade names such as Macrynol, Setalux, Synocure and Uracron, and the specific examples of suitable commercially available polyacrylic acid polyols are Macrynal SM 2810 / 75BAC, Setalux 1914, Setalux 1907, Setalux 1909, Synocure 580BA75, Synocure 865EEP 70, Uracron CY240 EF-75.

[0123] "Polyester polyol" refers to any polymer containing more than one ester functional group. In addition, "polyester polyol" contains at least two hydroxyl functional groups. The functionality (i.e., the number of hydroxyl groups present per molecule) of a polyester polyol can range from 2 to 10.

[0124] Preferably, the polyester polyol is a polyester polyol comprising the following repeating units:

[0125]

[0126] Where R 3 Selected from linear or branched C 1-20 Alkyl, C 3-12 Cycloalkyl and optionally substituted C 6-20 A group consisting of aryl groups; and

[0127] p is an integer from 2 to 50.

[0128] Preferably, R 3 Is it a straight chain or branched chain C 1-20 Alkyl. The term "alkyl" is intended to include straight or branched chain alkyl groups, such as propyl, butyl, pentyl and hexyl. Particularly preferred alkyl groups are pentyl and hexyl. In all embodiments, the alkyl group is preferably straight chain. It should be understood that "alkyl" in the context of polyester polyols is divalent and can therefore also be referred to as "alkylene".

[0129] In a particularly preferred embodiment, R 3 It is C 1-6 alkyl.

[0130] Particularly preferred cycloalkyl groups include cyclopentyl and cyclohexyl.

[0131] Examples of the substituted aryl group include aryl groups substituted with at least one substituent selected from halogen, alkyl groups having 1 to 8 carbon atoms, acyl groups or nitro groups. Particularly preferred aryl groups include substituted and unsubstituted phenyl, benzyl, phenylalkyl or naphthyl groups.

[0132] Preferably, p is an integer in the range of 2 to 25, such as 2 to 20, for example 3 to 15.

[0133] M of polyester polyol n Preferably it is 200 to 20,000, such as 500 to 10,000.

[0134] The polyester polyols of the present invention preferably have a hydroxyl number of 50-350, such as 100-300, for example 150-300 mg KOH / g (calculated on solids).

[0135] The viscosity of the polyester polyol at 23° C. may range from 10 mPa·s to 20000 mPa·s, such as 100 mPa·s to 15000 mPa·s, and in particular from 500 mPa·s to 10000 mPa·s.

[0136] The polyester polyols used in the present invention are commercially available. Commercial suppliers include Arkema, Covestro, DSM (now Covestro) and Nuplex, and suitable polyester polyols are sold under trade names such as Setal, Desmophen, Synolac and Uralac. Specific examples of suitable commercially available polyester polyols are Setal 169SS-67, Synolac 5086 and Uralac SY946.

[0137] In a preferred embodiment, the LEP coating composition (B) comprises at least one polymer selected from polyaspartates, polyether aspartates and mixtures thereof. The LEP coating composition may also comprise a mixture of two or more different polyaspartates and / or two or more different polyether aspartates.

[0138] In one embodiment, the first component contains only one polyaspartic acid. Therefore, in this embodiment, the polyaspartic acid consists of polyaspartic acid ester or polyether aspartic acid ester, preferably polyaspartamide.

[0139] In an alternative embodiment, the first component comprises a mixture of at least one polyaspartic acid ester and at least one polyether aspartic acid ester. In this embodiment, the weight ratio of at least one polyaspartic acid ester to at least one polyether aspartic acid ester is preferably in the range of 99:1 to 1:99, more preferably 75:25 to 25:75, even more preferably 50:50.

[0140] Any suitable polyaspartate may be used, but typically the polyaspartate is a polyaspartate comprising a sterically hindered secondary amine and an ester group. Suitable polyaspartates are described in WO2016049104A1.

[0141] The polyaspartic acid ester may include one or more polyaspartic acid esters corresponding to formula (I):

[0142]

[0143] wherein: q is an integer from 2 to 6; Z represents an aliphatic residue; and R4 and R5 represent organic groups which are inert to isocyanate groups under the reaction conditions and which may be the same or different organic groups.

[0144] In formula (I), the aliphatic residue Z may correspond to a linear or branched alkyl and / or cycloalkyl residue of an n-valent polyamine which reacts with a dialkyl maleate in a Michael addition reaction to give a polyaspartate. For example, the residue Z may correspond to an aliphatic residue from an n-valent polyamine, including but not limited to ethylenediamine; 1,2-propylenediamine; 1,4-butylenediamine; 1,6-hexanediamine; 2,5-diamino-2,5-dimethylhexane; 2,2,4-trimethyl-6-hexanediamine and / or 2,4,4-trimethyl-6-hexanediamine; 1,11-diaminoundecane; 1,12-diaminododecane; 1-amino-3,3,5-trimethyl-5-amino-methylcyclohexane; 2,4'-diaminodicyclohexylmethane and / or 4,4'-diaminodicyclohexylmethane; 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane; 2,4,4'-triamino-5-methyldicyclohexylmethane; aliphatic primary amino groups and M n 148 to 6000 g mol -1 Polyether polyamine; any isomers thereof and any combination thereof.

[0145] In certain embodiments, the residue Z is obtainable from 1,4-butanediamine; 1,6-hexanediamine; 2,2,4-trimethyl-1,6-hexanediamine and / or 2,4,4-trimethyl-1,6-diaminohexane; 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane; 4,4'-diaminodicyclohexylmethane; 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane; or 1,5-diamino-2-methyl-pentane.

[0146] In certain embodiments, the polyaspartic acid ester includes one or more compounds corresponding to formula (I), wherein q is an integer from 2 to 6, in some embodiments, q is an integer from 2 to 4, and in some embodiments, q is 2.

[0147] Examples of commercially available polyaspartic acid esters are Desmophen NH 1220, NH 1420, NH 1422, NH 1423, NH 1423LF, NH 1520 NH 1521 and NH 1523LF, all from Covestro, F220, F221, F420, F421, F520, all from Feiyang, and IC20 and IC40 from Evonik.

[0148] Any suitable polyether aspartate may be used, but typically the polyether aspartate is a polyether aspartate having the following formula (II):

[0149]

[0150] Each R 6 Indicates straight or branched chain C1-C 10 An alkyl residue, such as a linear or straight-chain C1-C6 alkyl residue, such as, for example, a methyl, ethyl, propyl or butyl residue; and wherein X is a polyether.

[0151] In one embodiment, the present invention is directed to a first component comprising a blend of polyether aspartates wherein X is a polyether having a repeating unit of the structure:

[0152]

[0153] where y is in the range of 2 to 35.

[0154] The blend of polyether aspartates may comprise at least two different polyether aspartates having different numbers of repeating units in X. In one embodiment, the blend is such that the average value of y is in the range of 2 to 10, such as 2 to 6, such as 2 to 4, such as 2.5 to 3.

[0155] Polyether aspartic acid esters can be prepared by reacting one or more polyether polyamines with dialkyl maleates (e.g., linear or branched C1-C 10 Maleic acid dialkyl esters, such as straight or linear C1-C6 maleic acid dialkyl esters, such as diethyl maleate) are reacted to prepare. For example, the polyether aspartic acid ester can be prepared by applying a certain amount of reactants so that there is at least one equivalent (and in some embodiments about one equivalent) of olefin double bonds per equivalent of primary amino groups. Examples of methods for preparing polyether aspartic acid esters can be found in WO 2014 / 151307 and Chen et al., RSC Advances (2018), 8: 13474-13481.

[0156] Suitable polyether polyamines that can be reacted with dialkyl maleates in a Michael addition reaction to produce polyether aspartates for use in the coating compositions of the present invention include JEFFAMINE polyetheramines commercially available from Fluntsman Corporation, The Woodlands, TX; for example, polyetheramines from the Jeffamine D series, such as, for example, Jeffamine D-230.

[0157] In one embodiment, the blend of polyetherpolyamines comprises a blend of polyetherpolyamines according to the following formula (III),

[0158]

[0159] wherein z is a number having an average value of at least 2, such as from 2 to 35, or from 2 to 8, or from 2.5 to 6.1, wherein the blend comprises: (1) about 50 to 99 wt%, such as from 50 to 90 wt%, or in some cases 80 to 90 wt% by weight of a polyether polyamine according to the formula, wherein z has an average value of 2.5; and (2) about 1 to 50 wt%, such as from 10 to 50 wt%, or in some cases 10 to 20 wt% of a polyether polyamine according to the formula, wherein z has an average value of 6.1.

[0160] Blends of polyether aspartic acid esters suitable for use in the present invention are Desmophen NH 1720 (formerly Desmophin NH2850XP) and Desmophens NH 1723LF from Covestro, which have an equivalent weight of about 290-295 gmol-1, a viscosity of ≥80 mPa·s at 25°C and an amine value of 170-210 mg KOH / g.

[0161] In one embodiment of the present invention, the first component a) in the LEP coating composition (B) further comprises an aldimine.

[0162] Any suitable aldimine may be used, and includes those prepared from an aldehyde and a polyamine containing two or more, preferably 2 to 6, and more preferably 2 to 4 primary amino groups. The polyamines include those having a molecular weight (in g mol -1 ) from 400 to about 10,000, preferably 800 to about 6,000, and low molecular weight amines having a molecular weight below 400. Examples of these polyamines are those in which the amino groups are attached to aliphatic, alicyclic, araliphatic and / or aromatic carbon atoms.

[0163] Suitable low molecular weight polyamine starting compounds include tetramethylenediamine, ethylenediamine, 1,2- and 1,3-propylenediamine, 2-methyl-1,2-propylenediamine, 2,2-dimethyl-1,3-propylenediamine, 1,3- and 1,4-butylenediamine, 1,3- and 1,5-pentanediamine, 2-methyl-1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-decanediamine, dialkylenediamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 4,4'-diaminodicyclohexylmethane, 2,4'-diaminodicyclohexylmethane and 2,2'-diaminodicyclohexylmethane, bis-(4-amino-3-methylcyclohexyl)-methane, 1,2-cyclohexanediamine and / or 1,4-cyclohexanediamine, 1,3-bis(methylamino)-cyclohexane, 1,8-p-menthanenediamine, hydrazine, semi-carbazide carboxylic acid), bishydrazides, bis-semicarbazides, phenylenediamine, 2,4-toluenediamine and / or 2,6-toluenediamine, 2,3-toluenediamine and / or 3,4-toluenediamine, polyphenylene polymethylene polyamines obtained by aniline / formaldehyde condensation, N,N,N-tris-(2-aminoethyl)-amine, guanidine, melamine, N-(2-aminoethyl)-1,3-propylenediamine, 3,3'-diamino-benzidine, polyoxypropyleneamine, polyoxyethyleneamine, 2,4-bis-(4'-amino-benzyl)-aniline and mixtures thereof.

[0164] Preferred polyamines are 1-amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane (isophoronediamine or IPDA), 4,4'-diaminodicyclohexylmethane, 2,4'-diaminodicyclohexylmethane and 2,2'-diaminodicyclohexylmethane, bis-(4-amino-3-methylcyclohexyl)-methane, 1,6-hexanediamine, 2-methylpentamethylenediamine and ethylenediamine. Particular preference is given to 4,4'-diaminodicyclohexylmethane, optionally in the form of a mixture with its isomers.

[0165] Suitable high molecular weight polyamines correspond to the polyols as defined below, which are used to prepare the NCO prepolymers, except that the terminal hydroxyl groups are converted to amino groups by amination or by reacting the hydroxyl groups with diisocyanates, followed by hydrolysis of the terminal isocyanate groups to amino groups. Preferred high molecular weight polyamines are amine terminated polyethers, such as the Jeffamine resins available from Texaco.

[0166] Suitable aldehydes are those corresponding to the formula O=CHCH(R1)(R2), wherein R1 and R2 may be identical or different and represent a hydrocarbon group, preferably containing 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms; or R1 and R2 together with the β-carbon atom form an alicyclic ring.

[0167] Examples of suitable aldehydes include isobutyraldehyde, 2-ethylhexanal, 2-methylbutyraldehyde, 2-ethylbutyraldehyde, 2-methylvaleraldehyde, 2,3-dimethylvaleraldehyde, 2-methylundecanal and cyclohexanecarbaldehyde.

[0168] Aldimines can be prepared in a known manner by reacting polyamines with aldehydes in stoichiometric amounts or with an excess of aldehyde. Excess aldehyde and the resulting water can be removed by distillation. The reaction can also take place in solvents other than ketones. After the reaction is complete, the solvent can also be removed by distillation.

[0169] A particularly preferred aldimine is isophoronediamine aldimine, for example Vestamin A-139 from Evonik.

[0170] The aldimine may be present in an amount of 3 to 30 wt %, preferably 5 to 20 wt %, relative to the total weight of the at least one polymer of component a) and the aldimine combined.

[0171] It should be understood that aldimines are unstable in the presence of moisture, and they can be stored as a third component to maintain functionality. In order to maintain the functionality of the aldimines, moisture scavengers such as molecular sieves, oxazolidines, p-toluenesulfonyl isocyanate, etc. can also be used.

[0172] The first component comprises at least one polymer selected from the group consisting of polyols, polyaspartates, polyether aspartates and mixtures thereof. Such polymers may form at least 30 wt % of component a), such as at least 50 wt % of component (a). Such polymers may form 30 to 60 wt % of component a).

[0173] Second component b)

[0174] The second component b) of the LEP coating composition (B) comprises at least one polyisocyanate curing agent.

[0175] Suitable polyisocyanate curing agents are well known in the art. Molecular weight is 168 to 300 g mol -1Examples of suitable low molecular weight polyisocyanates include hexamethylene diisocyanate (HDI), 2,2,4-trimethyl-1,6-hexamethylene diisocyanate and / or 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,4-diisocyanato-1-methyl-benzene (toluene diisocyanate, TDI), 2,4-diisocyanato-1-methylbenzene, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (I The invention also comprises 1,5-pentamethylene diisocyanate (PDI), 2,4'-diisocyanato-dicyclohexylmethane and / or 4,4'-diisocyanato-dicyclohexylmethane, 2,4-diisocyanato-diphenylmethane and / or 4,4'-diisocyanato-diphenylmethane and mixtures of these isomers with their higher homologues, which mixtures are obtained in a known manner by phosgenation of aniline / formaldehyde condensates, 2,4-diisocyanatotoluene and / or 2,6-diisocyanatotoluene; and any mixtures of these compounds.

[0176] In some preferred LEP coating compositions of the present invention, the polyisocyanate curing agent is selected from aliphatic polyisocyanates, such as HDI, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate and / or 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, IPDI, 2,4'-diisocyanato-dicyclohexylmethane and / or 4,4'-diisocyanato-dicyclohexylmethane and 2,4-diisocyanato-diphenylmethane and / or 4,4'-diisocyanato-diphenylmethane.

[0177] In the preferred LEP coating composition of the present invention, the polyisocyanate curing agent is a derivative of the above-mentioned monomeric polyisocyanate, which is conventional in the art. These derivatives include polyisocyanates containing trimer or biuret groups. Examples of particularly preferred derivatives include N, N', N"-tri-(6-isocyanatohexyl)-biuret and mixtures thereof with higher homologues thereof, and N, N', N"-tri-(6-isocyanatohexyl)-isocyanurate and mixtures thereof with higher homologues thereof containing more than one isocyanurate ring.

[0178] Polyisocyanates for use in the present invention are commercially available. Commercial suppliers include Covestro, BASF, Asahi Kasei, Wanhua and Vencorex, and suitable polyisocyanates (iii) are sold under trade names such as Desmodur, Duranate, Tolonate, Wannate and Basonate.

[0179] Prepolymers and semi-prepolymers containing isocyanate groups based on the above-mentioned monomeric polyisocyanates, and organic polyhydroxy or amine compounds, are also preferably used as polyisocyanate curing agents. These prepolymers and semi-prepolymers generally have an isocyanate content of 0.5 to 30% by weight, preferably 1 to 20% by weight, and are prepared in a known manner by reacting the above-mentioned starting materials (monomeric polyisocyanates and organic polyhydroxy or amine compounds) in an NCO / OH equivalent ratio of 1.05:1 to 10:1, preferably 1.1:1 to 3:1, this reaction optionally followed by distillation to remove any unreacted volatile starting polyisocyanates still present.

[0180] Prepolymers and semi-prepolymers can be made from molecular weights ranging from 50 to 3000 g mol -1 Examples include ethylene glycol, propylene glycol, trimethylolpropane, 1,6-dihydroxyhexane; low molecular weight hydroxyl-containing esters of these polyols with dicarboxylic acids of the types exemplified below; low molecular weight ethoxylation and / or propoxylation products of these polyols; and mixtures of the aforementioned multivalent modified or unmodified alcohols.

[0181] Preferably, the prepolymers and semi-prepolymers are prepared from relatively high molecular weight polyols having at least two hydroxyl groups (preferably two) per molecule and more preferably having a hydroxyl content of 0.5-17 wt%, preferably 1-10 wt%.

[0182] Commercially available isocyanate prepolymers are available, for example, from Covestro under the trade name Desmodur, from Lanxess under the trade name or It is available from Anderson Development Company under the trade name ANDUR or from the COIM group under the trade name Versathane.

[0183] In a particularly preferred embodiment, the polyisocyanate curing agent comprises a mixture of a polyisocyanate prepolymer and a polyisocyanate trimer (eg, IPDI trimer).

[0184] At least one polyisocyanate curing agent is preferably present in an amount of 80 to 100 wt%, preferably 85 to 100 wt%, such as 90 to 100 wt%, relative to the total weight of the second component b). Thus, component b) may consist of a polyisocyanate curing agent.

[0185] The weight ratio between components a) and b) can vary depending on the nature of the components. Typical weight ratios are 1:3 to 3:1. It is possible that component b) is in excess.

[0186] In the most preferred embodiment, at least one polyol resin (i) is preferably present in an amount of 10 to 90 wt %, preferably 30 to 80 wt %, more preferably 60-75 wt % relative to the dry weight of the tie layer composition (A);

[0187] The isocyanate compound (ii) is present in an amount of 10 to 90 wt %, preferably 20 to 80 wt %, more preferably 30-60 wt % relative to the dry weight of the tie layer composition (A);

[0188] Polyols, polyaspartates, polyether aspartates and mixtures thereof form 30 to 60 wt % of said component a);

[0189] The second component b) consists of at least one polyisocyanate curing agent; and

[0190] The weight ratio of components a) to b) is 3:1 to 1:3.

[0191] Other components

[0192] The LEP coating composition (B) of the present invention may also contain other substances commonly used in coating formulations, such as compatibilizers, pigments, matting agents, solvents and additives such as waxes, dyes, dispersants, wetting agents, defoamers, surfactants, adhesion promoters, light stabilizers, dehydrating agents and thixotropic agents.

[0193] In a specific embodiment, the LEP coating composition comprises an adhesion promoter. Examples of suitable adhesion promoters include alkoxysilanes, such as Dynasylan AMEO, Dynasylan 1189, and Silquest A1524 (VPS2101 from Evonik, 3-ureidopropyltrimethoxysilane) and NCO-alkoxysilane hybrids, such as 2873.

[0194] The additives generally form up to about 50 wt%, such as 25 wt%, for example up to 20 wt%, ideally up to 15 wt%, based on the total weight of the LEP coating composition as a whole. The additives may be present in only 1 wt% or less of the LEP coating composition.

[0195] Examples of compatibilizers are minerals such as dolomite, plastorite, calcite, quartz, barite, magnesite, silica, nepheline syenite, wollastonite, talc, chlorite, mica, kaolin, pyrophyllite and feldspar; synthetic inorganic compounds such as calcium carbonate, magnesium carbonate, barium sulfate, calcium silicate and silica; polymer microspheres and inorganic microspheres such as uncoated or coated hollow and solid glass beads, uncoated or coated hollow and solid ceramic beads; porous and dense beads of polymeric materials such as poly(methyl methacrylate), poly(methyl methacrylate-co-ethylene glycol dimethacrylate), poly(styrene-co-ethylene glycol dimethacrylate), poly(styrene-co-divinylbenzene), polystyrene, poly(vinyl chloride). Pigments of interest include organic pigments and inorganic pigments such as titanium dioxide.

[0196] Preferred examples of suitable solvents are organic solvents such as toluene, xylene and naphtha solvents; ketones such as methyl ethyl ketone, methyl isobutyl ketone, diacetone alcohol and cyclohexanone; esters such as methoxypropyl acetate, n-butyl acetate and 2-ethoxyethyl acetate; and mixtures thereof. Particularly preferred solvents are esters such as n-butyl acetate, tert-butyl acetate, 1-methoxy-2-propyl acetate, most preferably n-butyl acetate and / or 1-methoxy-2-propyl acetate.

[0197] The solvent preferably forms less than 20 wt % of the LEP coating composition (B). It should be understood that the wt % range of the solvent is relative to the weight of the LEP coating composition (B) as a whole before curing (i.e. before the coating is cured and dried). Any pigment preferably accounts for 10 to 30 wt %, such as 15 to 25 wt %, relative to the total weight of the LEP coating composition (B) as a whole. The compatibilizer generally preferably accounts for 0 to 40 wt %, preferably 2.5 to 30 wt %, such as 5 to 20 wt %, relative to the total weight of the LEP coating composition (B) as a whole.

[0198] Coating Systems and Application

[0199] In a preferred embodiment, the coating system of the present invention can be cured at ambient temperature (preferably room temperature), i.e., when the components are mixed, the tie layer composition (A) and / or the LEP coating composition (B) will cure at a temperature in the environment in question without applying heat. This is typically in the range of 5 to 50° C. Preferably, curing occurs at 10 to 35° C., more preferably at room temperature, i.e., in the range of 15 to 30° C. It should be understood that since the coating systems of the present invention are curable, they may be referred to as curable coating systems.

[0200] The coating system preferably consists of several coatings. Each layer preferably consists of several parts (e.g. two or more parts) to prevent premature curing and is therefore shipped as a kit.

[0201] The coating system of the present invention can be used to coat a substrate. Suitable substrates include aircraft wings, wind turbine blades, rotor blades, propellers, radomes, antennas, fan blade nose cones, and high-speed vehicles such as trains or airplanes. Preferably, the substrate is selected from the group consisting of aircraft wings, wind turbine blades, rotor blades, propellers, and fan blade nose cones.

[0202] In a particularly preferred embodiment, the substrate is a wind turbine blade. Typical turbine blades are composed of materials including synthetic resin composites including epoxy resins, vinyl ester resins, glass or carbon fiber reinforced resins. In a particularly preferred embodiment, the substrate is the leading edge of a wind turbine blade.

[0203] Thus, in another aspect, the present invention relates to a substrate at least partially coated with a coating system as defined above. The present invention also relates to the use of a coating system as defined above for coating at least a portion of a substrate, wherein the substrate is preferably a wind turbine blade, more preferably a leading edge of a wind turbine blade.

[0204] The coating system can be applied by any conventional method, such as brushing, rolling or spraying (airless or conventional). Preferably, conventional spraying is used.

[0205] The present invention also relates to a method for coating at least a portion of a substrate with a coating system as defined above, the method comprising applying a tie layer composition (A) to the surface of the substrate and curing the composition (A), and subsequently applying a LEP coating composition (B) directly on the composition (A) and curing the composition (B).

[0206] Typically, the interval between applying the tie layer composition and the LEP coating composition is less than 24 hr, preferably in the range of 1 to 24 hr, more preferably 1 to 12 hr, such as 1 to 6 hr at 23°C and 50% relative humidity.

[0207] As mentioned above, in the context of the present invention, the term "tie layer" refers to a layer that acts as a bridge between, for example, a substrate, a primer or basecoat or a filler and a LEP coating. Therefore, it should be understood that when we refer to a "substrate" or a "substrate surface", we mean the substrate itself or any pretreatment layer that has been applied to at least a portion of the substrate. Thus, the coating system of the present invention can be applied directly to at least a portion of the substrate, or applied to any pretreatment layer designed for a polyurethane or polyurea topcoat based on a polyol, polyamine, polyaspartate or polyether aspartate.

[0208] In a preferred embodiment, the coating system of the present invention is applied as part of a coating system comprising, in sequence, an optional filler layer (also often referred to as putty, such as a polyurethane with a high compatibilizer content), a primer layer (such as a polyurethane or polyurea), a tie layer and a LEP coating, wherein the coating system of the present invention forms the tie layer and the LEP coating. Sometimes the LEP coating may be overcoated with another coating, but most commonly the LEP coating is the outermost coating in the coating system. Preferably, the primer is a water-based, solvent-based or solvent-free polyurethane or polyaspartic coating. Preferably, the filler is a polyurethane coating with a high solids content, preferably 80-100 wt% solids, typically greater than 97 wt% solids.

[0209] Preferably, the compositions (A) and (B) in the coating system of the present invention are transported as a set, and preferably the first component and the second component of each of the compositions (A) and (B) are separated from each other to prevent curing before application to the desired surface. Before use, the components should be combined and thoroughly mixed. Conventional mixing techniques can be used.

[0210] The layers formed using the coating system of the present invention preferably have the following dry film thicknesses: filler (0-2000 μm, applied in 0-3 layers), primer (60-150 μm, applied in 1-2 layers), tie layer (20-50 μm, applied in 1 layer), LEP coating (150-500 μm, applied in 2-6 layers). It should be understood that any layer can be laid down using a single or multiple application of the coating, depending on the application method and the area of ​​use.

[0211] The invention will now be described with reference to the following non-limiting examples.

[0212] Example

[0213] General Procedure for Preparing Compositions and Coated Substrates

[0214] The two components of various tie layer compositions (IE = Inventive Example (according to the invention); CE = Comparative Example) were prepared by combining the corresponding ingredients and mixing them uniformly in a dissolver. For each composition, the two components were uniformly mixed in the proportions shown in Table 1 / 2. The tie layer composition was applied immediately after preparation (brush application).

[0215] The tie layer composition was applied to GRP specimens or GRP specimens coated with a commercially available 2K polyurethane based primer. The coating was allowed to dry for 2 hours before applying the LEP coating. The dry film thickness of the cured coating was 20 to 40 μm.

[0216] Similarly, LEP coatings were prepared (LEP coating compositions are given in the table below) and applied over the tie layer. Curing was typically performed by storage at 23°C for 2 weeks. The coating was applied in two layers (dry film thickness 2 x 150 μm) with a brush, drying for 2-3 hrs between each layer of coating. The total dry film thickness of the cured coating was 300 μm.

[0217] Test Method

[0218] Adhesion:

[0219] Adhesion was tested by the cross-hatch method according to ASTM D 6677, but using the ratings shown below:

[0220]

[0221] Two different systems were tested:

[0222] 1: GRP+adhesive layer+LEP layer

[0223] 2: GRP+primer+bonding layer+LEP layer

[0224] The adhesion results of these two systems are indicated as Adhesion (1) or Adhesion (2), respectively. The results of the adhesion tests are shown in Table 1 / 2.

[0225] Material:

[0226]

[0227]

[0228] The OHEW (OH equivalent weight) given is an approximate value calculated from the EEW value and assumes that all repeat units are BADGE.

[0229] The LEP coating composition used was as follows:

[0230]

[0231]

[0232] Table 1: Tie layer composition by weight and adhesion test results after coating with LEP coating composition

[0233] IE1 IE2 IE3 IE4 IE5 IE6 IE7 IE8 IE9 IE10 IE11 IE12 IE13 Component (i) Resin 4 31.5 31.5 31.5 31.5 20.5 Resin 1 31.5 Resin 5 31.5 Resin 3 31.5 31.5 Resin 6 11.0 Resin 7 11.0 Resin 2 31.5 Resin 8 11.0 Resin 9 Resin 10 Resin 11 Butyl acetate 89 89 pigment 35 PMA glycol ether 31.5 31.5 31.5 31.5 31.5 31.5 31.5 31.5 31.5 20.5 Xylene 37 37 37 37 37 37 37 37 37 24 MIBK 89 Component (ii) Isocyanate 1 4.0 4.0 4.0 10.9 Isocyanate 2 25.7 25.7 25.7 19.2 19.2 25.6 25.7 16.7 Tackifier 6.9 6.9 6.4 Isocyanate 3 17.4 Butyl acetate 6 6 6 3.5 NCO:OH Ratio 0.78:1 0.76:1 0.77:1 0.77:1 0.77:1 0.95:1 0.77:1 0.77:1 0.78:1 0.77:1 Adhesion(1) 1 1 1 1 2 1 0-1 0-1 1 1 2 2 1 Adhesion(2) 1 1 1 1 2 4 0-1 0 0 1 2 2 2

[0234] Table 2 - Comparative Examples

[0235] CE1 CE2 CE3 CE4 CE5 Component (i) Resin 3 31.5 Resin 9 31.5 Resin 10 31.5 Resin 11 31.5 Butyl acetate pigment PMA glycol ether 31.5 31.5 31.5 31.5 Xylene 37 37 37 37 Component (ii) Isocyanate 2 100 25.7 25.7 25.7 NCO:OH Ratio N / A N / A 1.1:1 0.83:1 0.81:1 Adhesion(1) 5 5 3 5 4 Adhesion(2) 5 5 5 5 5

[0236] Comparative Examples 3-5 with lower Mn epoxy resins provided poor adhesion. CE1 without component (ii) and CE2 without component (i) also provided poor adhesion.

[0237] Rainwater erosion test

[0238] The rain erosion test was carried out according to standard ASTM G73-10, where the GRP panel was airfoil shape, the exposed area length of the droplet impacting the panel was 23 cm, and it was coated with the coating system given in Table 3. The coated test panel was attached to each of the three rotating arms and rotated at 1527 rpm = 160 m s -1 , 15-35℃, precipitation intensity 30-35mm h -1 The test is conducted under 30-minute exposure conditions, with inspections every 30 minutes to visually monitor the erosion of the coating system. For a coating system to pass the test, the coating on the test object should have minimal or no visible damage or delamination after 3 hours of exposure. After 3 hours of exposure, high-performance coating systems have no visible damage or delamination of the coating system.

[0239] Table 3. RET results of GRP samples coated with topcoat, tie layer and LEP after 3 hr exposure.

[0240] System 1 (Comparative Example) System 2 (Invention Example) Adhesive layer - IE3 LEP LEP LEP result Failed, severe delamination Pass, no delamination

[0241] Including a tie coat in a coating system can significantly improve rain erosion performance.

Claims

1. A coating system comprising at least two layers A and B, wherein the layers A and B are adjacent, and wherein layer A comprises: (A) a bonding layer composition comprising: (i) a first component comprising at least one polyol resin; and (ii) a second component comprising an isocyanate compound; and Layer B contains: (B) A leading edge protection (LEP) coating composition comprising: a) a first component comprising at least one polymer selected from the group consisting of polyols, polyaspartates, polyether aspartates, and mixtures thereof; and b) A second component comprising at least one polyisocyanate curing agent.

2. A coating system comprising at least two layers A and B, wherein the layers A and B are adjacent, and wherein layer A comprises: (A) a bonding layer composition comprising: (i) a first component comprising at least one polyol resin; and (ii) a second component comprising an isocyanate compound, wherein the first component and the second component have been mixed and cured; and Layer B contains: (B) A leading edge protection (LEP) composition comprising: a) a first component comprising at least one polymer selected from the group consisting of polyols, polyaspartates, polyether aspartates, and mixtures thereof; and b) a second component comprising at least one polyisocyanate curing agent, The first component and the second component have been mixed and cured.

3. The coating system according to claim 1 or 2, wherein: The polyol resin (i) in (A) is an epoxy resin, preferably having an epoxy equivalent weight (EEW) of 1100-7000 g eq. -1 , preferably 2000-5000g eq -1 of epoxy resin.

4. The coating system according to claim 3, wherein: The epoxy resin is bisphenol A epoxy resin.

5. The coating system according to claim 3 or 4, wherein: The epoxy resin is type 8 epoxy resin or type 9 epoxy resin, preferably type 9 epoxy resin.

6. The coating system according to claim 1 or 2, wherein: The polyol resin (i) in (A) is a phenolic resin, preferably a novolac resin.

7. The coating system according to any one of claims 1 to 6, wherein: The number average molecular weight (Mn) of the polyol resin (i) in (A) is at least 1500 g mol -1 , preferably at least 2000 g mol -1 , more preferably at least 3500 g mol -1 .

8. The coating system according to any one of claims 1 to 7, wherein: The isocyanate compound (ii) in (A) includes polyisocyanates, preferably aromatic polyisocyanates.

9. The coating system according to any one of claims 1 to 8, wherein: The at least one polyol resin (i) is present in an amount of 10 to 90 wt%, preferably 30 to 80 wt%, more preferably 60 to 75 wt%, relative to the dry weight of the tie layer composition (A).

10. The coating system according to any one of claims 1 to 9, wherein: The isocyanate compound (ii) is present in an amount of 10 to 90 wt %, preferably 20 to 80 wt %, more preferably 30 to 60 wt %, relative to the dry weight of the tie layer composition (A).

11. The coating system according to any one of claims 1 to 5 or 7 to 10, wherein: The ratio of NCO to amine and hydroxyl (NH+OH) or the ratio of NCO to hydroxyl is 0.4-1.1, preferably 0.6-1.0, more preferably 0.7-0.9, even more preferably 0.8, based on the moles of the total tie layer composition (A).

12. The coating system according to any one of claims 1 to 11, wherein: The at least one polyisocyanate curing agent b) in (B) is a polyisocyanate prepolymer or a mixture of a polyisocyanate prepolymer and a polyisocyanate trimer.

13. The coating system according to any one of claims 1 to 12, wherein: The first component a) in the LEP coating composition (B) further comprises an aldimine.

14. The coating system according to any one of claims 1 to 13, wherein: The coating system comprises three layers X, A, B in sequence, wherein layers A and B are as defined in any one of the preceding claims and layer X is a polyaspartic or polyurethane layer.

15. A coating system according to any one of the preceding claims, wherein: The polyol resin in (A) is: Epoxy resins, such as bisphenol A epoxy resins, wherein the epoxy resin as the polyol resin (i) in (A) has a number average molecular weight (Mn) of at least 3000 g mol -1 , preferably at least 3500 g mol -1 ;or The polyol resin is a phenolic resin, preferably a novolac resin.

16. A coating system according to any one of the preceding claims, wherein: At least one polyol resin (i) is present in an amount of 10 to 90 wt %, preferably 30 to 80 wt %, more preferably 60 to 75 wt %, relative to the dry weight of the tie layer composition (A); The isocyanate compound (ii) is present in an amount of 10 to 90 wt %, preferably 20 to 80 wt %, more preferably 30 to 60 wt %, relative to the dry weight of the tie layer composition (A); The polyols, polyaspartates, polyether aspartates and mixtures thereof form 30 to 60 wt % of the component a); The second component b) consists of the at least one polyisocyanate curing agent; and The weight ratio of components a) to b) is 3:1 to 1:

3.

17. A substrate at least partially coated with a coating system as defined in any one of claims 1 to 16.

18. The substrate according to claim 17, wherein The substrate is a wind turbine blade, preferably a leading edge of a wind turbine blade.

19. Use of a coating system as defined in any one of claims 1 to 16 for coating at least a portion of a substrate, wherein the substrate is preferably a wind turbine blade, more preferably a leading edge of a wind turbine blade.

20. A method for coating at least a portion of a substrate with a coating system as defined in any one of claims 1 to 16, the method comprising applying a tie layer composition (A) to the surface of the substrate and allowing the composition (A) to cure, and then applying a LEP coating composition (B) directly on top of the composition (A) and allowing the composition (B) to cure.

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