WO2017087379A1

WO2017087379A1 - Epoxy backer coatings

Info

Publication number: WO2017087379A1
Application number: PCT/US2016/062018
Authority: WO
Inventors: Yue Shen; Liang Hong; Hongying Chen
Original assignee: Blue Cube Ip Llc
Priority date: 2015-11-16
Filing date: 2016-11-15
Publication date: 2017-05-26
Also published as: CN109071771A; TW201723107A

Abstract

A coating composition comprising (a) an epoxy resin composition comprising a reaction produce of (i) an epoxy resin, (ii) a compound containing a cardanol moiety, and (iii) reactive agent selected from a carboxylic acid, a phenolic compound, or mixture thereof and (b) an amino crosslinker compound, process for preparing a cured coating composition, and articles comprising the coating composition.

Description

EPOXY BACKER COATINGS

FIELD OF THE INVENTION

[0001 ] The present disclosure generally relates to epoxy backer coating compositions and uses thereof.

BACKGROUND OF THE INVENTION

[0002] Epoxy resins are one of the most important classes of

thermosetting polymers with large use in protective coatings for many coating

industries. However, epoxy resins, when cured, are brittle; and the poor flexibility of epoxy resins limits the application of such epoxy resins in backer coatings applications. Typically, an epoxy-modified resin is used in backer coating applications.

[0003] For example, a "Type 9" epoxy resin has been widely used to modify a hexamethoxymethylmelamine (HMMM) cured polyester; and such epoxy- modified polyester resin has been used for backer coating applications. "Type 1 " to "Type 9" epoxy resins are common epoxy industry terms to characterize epoxy resins based on the molecular weight (MW) of the epoxy resins as well known in the art.

Together, the Type 9 epoxy resin and the cured polyester resin achieve a good performance balance for the backer coating in terms of thermal resistance (during curing), chemical resistance, flexibility, and good adhesion to polyurethane (PU) foam. However, the combination of the Type 9 epoxy resin and the cured polyester resin has a disadvantage in that both the Type 9 epoxy resin and the polyester resin are high molecular weight (e.g., greater than[> 3,800) products which exhibit very high viscosities (e.g., > 4,600 mPa-s at 25 °C).

[0004] Formulated paints made using the above known epoxy-modified polyester resin have low weight solid content (e.g., less than 60 % by weight and about 40 % by volume) and high (e.g., > about 420 g/L) volatile organic compounds (VOC). Typically, the weight solid content of the above known epoxy-modified polyester resin is normally less than 50 percent by volume (volume %); and the VOC content of the above known epoxy-modified polyester resin is normally greater than 420 g/L. [0005] Therefore, a market demand exists to produce coating compositions that have a high solid content (e.g., greater than 50 volume %) and low VOC (e.g., less than 420 g/L) due to increased environmental protections and regulations.

SUMMARY OF THE INVENTION

[0006] Among the various aspects of the present disclosure is the provision of a class of backer coating compositions based on an epoxy resin

composition, articles which utilize these backer coating compositions, and the methods to prepare and cure these compositions.

[0007] One aspect of the present disclosure encompasses a coating composition comprising (a) an epoxy resin composition at a concentration of about 35 weight percent to about 45 weight percent, and (b) an amino crosslinker compound.

[0008] Another further aspect of the present disclosure encompasses a process for preparing a cured coating. The process comprises providing a curable coating composition comprising (a) about 35 weight percent to about 45 weight percent of an epoxy resin composition and (b) an amino crosslinker compound; and heating the curable coating composition to a temperature from about 100°C to about 300°C to form the cured coating.

[0009] A further aspect of the present disclosure provides an article comprising a substrate and a coating adhering to at least a portion of a surface of the substrate, wherein the coating is prepared by applying a coating composition

comprising (a) about 35 weight percent to about 45 weight percent of an epoxy resin composition, and (b) an amino crosslinker compound.

[0010] Other features and iterations of the invention are described in more detail below.

BRIEF DESCRIPTION OF FIGURES

[001 1 ] For the purpose of illustrating the present invention, the drawings show a form of the present invention which is presently preferred. However, it should be understood that the present invention is not limited to the embodiments shown in the drawings.

[0012] Figure 1 is a schematic cross-sectional view showing a portion of a primer coating film on a metal plate.

[0013] Figure 2 is a schematic cross-sectional view showing a portion of a primer coating film on a metal plate and a backer coating on the primer coating film.

[0014] Figure 3 is a schematic cross-sectional view showing a substrate with various layers including a primer coating film layer and a backer coating layer on the top surface of a metal substrate and a primer coating film layer and a backer coating layer on the bottom surface (or back surface) of the same a metal substrate.

[0015] Figure 4 is a schematic cross-sectional view showing a substrate with several layers including a primer coating film layer, a backer coating layer, a pretreatment layer, and a zinc layer on the top surface (or front surface) of a metal substrate, and a primer coating film layer, a backer coating layer, a pretreatment layer, and a zinc layer on the bottom surface (or back surface) of the same a metal substrate.

DETAILED DESCRIPTION OF THE INVENTION

[0016] The present disclosure provides epoxy backer coating

compositions comprising an epoxy resin composition and an amino crosslinker compound. These backer coating compositions, once applied to a metal substrate and cured, provide many beneficial attributes such as high mechanical strength, a high temperature performance, high flexibility, a high anticorrosion performance, and have low volatile organic compound (VOC) emissions.

(I) Backer Coating Compositions

[0017] One aspect of the disclosure provides backer coating compositions comprising an epoxy resin composition and an amino crosslinker compound. In general, the backer coating composition is a curable backer coating composition. (a) epoxy resin composition

[0018] In general, the epoxy resin composition comprises a reaction product of an epoxy resin, a compound containing a cardanol moiety, and a reactive agent selected from a carboxylic acid, a phenolic compound, or mixtures thereof.

[0019] Generally, both the compound containing a cardanol moiety and the reactive agent containing reactive groups, such as hydroxyl or carboxylic acid groups react with epoxy groups in the epoxy resin. When the ratio of the epoxy resin to the compound containing a cardanol moiety and the reactive agent are close to stoichiometry, the reaction product generally haw a high molecular weight. If the epoxy resin is in large excess, then the final reaction product generally contains a large portion of residual epoxy resin and epoxy groups. On the contrary, if the compound containing the cardanol moiety and the reactive agent are in excess, most epoxy groups generally are consumed by the reactive hydroxyl and carboxylic acid groups. In addition, if the ranges detailed below are not used in the epoxy resin composition, unacceptable viscosity or unacceptable epoxy equivalent weight (EEW), and a different T_d property may result.

[0020] In general, the weight percent of the epoxy resin composition in the backer coating composition may range from 35 weight % to about 45 weight %. In various embodiments, weight percent of the epoxy resin composition may range from about 35 weight % to about 45 weight %, from about 36 weight % to about 44 weight %, from about 38 weight % to about 42 weight %, or from 39 weight % to about 41 weight %. In embodiments, the weight percent of the epoxy resin in the backer coating composition may be about 40 weight %.

(i) components of the epoxy resin composition

[0021 ] Epoxy resin. A wide variety of epoxy resins may be used to prepare the epoxy resin composition. In general, the epoxy resin is curable. Any epoxy resin that improves the mechanical and thermal performance of the epoxy resin composition may be used in this capacity. Non-limiting examples of epoxy resin or polyepoxides include aliphatic, cycloaliphatic, aromatic, hetero-cyclic epoxy compounds, and mixtures thereof. In a preferred embodiment, the epoxy resin may contain, on average, at least one reactive oxirane group. Epoxy resins useful in the epoxy resin compositions used herein include for example mono-functional epoxy resins, multi- or poly-functional epoxy resins, and combinations thereof. In some embodiments, the epoxy resins useful in the present invention and the preparation of such epoxy resins are disclosed, for example, in Lee, H. and Neville, K., Handbook of Epoxy Resins, McGraw-Hill Book Company, New York, 1967, Chapter 2, pages 2-1 to 2-27,

incorporated herein by reference. A detailed description and the preparation of the epoxy resin can also be found in International Patent Publication No. WO 2008/045894, incorporated herein by reference.

[0022] In preferred embodiments, the epoxy resin may be in liquid form, termed a liquid epoxy resin (LER). Non-limiting examples of the liquid epoxy resin which may be useful in the present invention may include, but are not limited to, D.E.R.™ 331 ; D.E.R. 354™; D.E.R. 332™; D.E.R. 330™; D.E.R. 383™; and mixtures thereof. The above D.E.R. epoxy resins are commercial products available from The Dow Chemical Company.

[0023] Compound containing a cardanol moiety. A variety of cardanol moiety-containing compounds may be used to prepare the epoxy resin composition. Suitable cardanol moiety containing compounds include for example cardanol, a compound containing a cardol moiety such as for example cardol, and mixtures thereof. Exemplary examples of the compound containing a cardanol moiety useful in the present invention includes an epoxidized cardanol, an epoxy resin modified cardanol, cashew nutshell liquid (CNSL), cardanol based anhydride, and mixtures thereof. A detailed description and the preparation of compounds containing cardanol moieties can be found in International Patent Publication No. WO 2014/1 17351 , incorporated herein by reference.

[0024] In another embodiment, the compound containing a cardanol moiety may be, for example, a glycidyl ether made of CNSL. The glycidyl ether made of CNSL compound may be one or more of the compounds described in "Epoxy resin from cardanol as partial replacement of bisphenol-A-based epoxy for coating application", J. Coat. Technol. Res., 2014, 1 1 , 601 -618, incorporated herein by reference.

[0025] One of the beneficial properties of cardanol moiety-containing compounds is their hydrophobicity that provides a formulation that repels water because water could facilitate corrosion of metal materials.

[0026] The molar ratio of the epoxy resin to the compound containing the cardanol moiety can and will vary. Generally, the molar ratio of the epoxy resin to the compound containing the cardanol moiety may range from 1 :0.05 to about 1 :0.75. In various embodiments, molar ratio of the epoxy resin to the compound containing the cardanol moiety may be about 1 :0.05 to 1 :0.75, from about 1 :0.10 to about 1 :0.5, from about 1 :0.20 to about 1 :0.40, or from about 1 :0.25 to about 1 :0.30.

[0027] Reactive agent. In general, the reactive agent is a carboxylic acid, a phenolic compound, or a mixture thereof. In various embodiments, the reactive agent may be a carboxylic acid or a dicarboxylic acid. Each of these carboxylic acids may contain from 2 to about 34 carbon atoms in an aliphatic or an aromatic moiety. Non- limiting examples of carboxylic acids may be acetic, propionic, butanoic, pentaenoic, caproic, heptanoic, caprylic, nonanioc, capric, undecanoic, lauric, tridecanoic, yristic, palmatic, margaric, stearic, nonadecanoic, arachidic, behenic, succinic, glutaric, adipic, glycolic, gluconic, lactic, malic, tartaric, ascorbic, glucuronic, maleic, fumaric, pyruvic, aspartic, glutamic, benzoic, anthranilic, mesylic, 4-hydroxybenzoic, phenylacetic, mandelic, embonic (pamoic), oxalic, malonic, succinic, pimelic, suberic, azelaic, sebacic, brassilic, dodecanedioic, and thapsic . In other embodiments, the reactive agent may be a phenol. Phenolic compounds that may be useful for preparing the epoxy resin composition include for example, an aromatic group with two hydroxyl functionalities (i.e., bis phenol). Non-limiting examples of these phenolic compounds may be bisphenol A, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol, G, bisphenol M, bisphenol, P, bisphenol PH, bisphenol S, bisphenol TMC, and bisphenol Z.

[0028] The molar ratio of the epoxy resin to the reactive agent can and will vary. Generally, the molar ratio of the epoxy resin to the reactive agent may range from about 1 :0.50 to about 1 : 1 .4. In various embodiments, molar ratio of the epoxy resin to the reactive compound may be from about 1 :0.50 to about 1 :1 .4, from about 1 :0.60 to about 1 :1 .3, from about 1 :0.75 to about 1 : 1 .2, or from about 1 :0.9 to about 1 :1 .10.

(ii) reaction to form the epoxy resin composition

[0029] The reaction commences with formation of a reaction mixture comprising an epoxy resin, a compound comprising a cardanol moiety, and a reactive agent. The reaction mixture may further comprise a catalyst. In some embodiments the reaction mixture may further comprise a solvent. Suitable solvents are known to those skilled in the art. These reaction components may be added all at the same time, sequentially, or in any order. The epoxy resin composition can be achieved by blending the above components in any known mixing equipment or reaction vessel. Also, the process for preparing the epoxy resin composition may be a batch or a continuous process.

[0030] In various embodiments, formation of the epoxy resin composition may be conducted in the presence of a catalyst. Suitable catalysts may include various quaternary phosphonium salt catalysts, quaternary ammonium salts, organic proton acceptors, and inorganic proton acceptors. Non-limiting examples of quaternary ammonium salts may include tetraethyl ammonium chloride, tetraethyl ammonium bromide, tetrabutyl ammonium chloride, tetrabutyl ammonium bromide, benzyltriethyl ammonium chloride, benzyltriethyl ammonium bromide, and benzyltriethyl ammonium iodide. Non-limiting examples of organic proton acceptors may include imidazole, benzimidazole, N-methylimidazole, N-acetylimidazole, N-butylimidazole, N- benzylimidazole, triethanolamine, ethyl methyl amine, dimethyl amine, diethyl amine, dicyclohexyl amine, methyl cyclohexyl amine, phenyl ethyl amine, dibenzyl amine, methyl benzyl amine, ethyl benzyl amine, cyclohexyl phenyl amine, dibutyl amine, ditertiarybutyl amine, dipropyl amine, dipentylamine, dicyclohexyl amine, piperidine, 2- methylpiperidine, 2,5-dimethylpiperidine, 2,6-dimethylpiperidine, piperazine, 2- methylpiperazine, 2,6-dimethylpiperazine, morpholine, trimethylamine, triethylamine, diisopropylethylamine, tripropylamine, tributylamine, 4-methylmorpholine, 4- ethylmorpholine, N-methylpyrrolidine, N-methylpiperidine, 1 ,8-diazabicyclo[5.4.0]undec- 7-ene, pyrazine, 4-dimethylaminopyridine, pyridine, (R)-a-methylbenzylamine, (S)-a- methylbenzylamine, a,a-diphenyl-2-pyrrolidinemethanol (DPP), and a,a-diphenyl-2- pyrrolidinemethanol trimethylsilyl ether (DPPT). Non-limiting examples of inorganic proton acceptors may include sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, cesium carbonate, sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, sodium borate, sodium

dihydrogen phosphate, disodium hydrogen phosphate, sodium methoxide, sodium tert- butoxide, and potassium tert-butoxide. Non-limiting examples of suitable quaternary phosphonium catalysts may include benzyltriphenylphosphonium chloride,

ethyltriphenylphosphonium acetate, ethyltriphenylphosphonium iodide, and

tetrabutylphosphonium acetate. In a preferred embodiment, the catalyst may be ethyltriphenylphosphonium acetate.

[0031 ] The weight percent ratio of the epoxy resin to the catalyst may vary depending on the type of epoxy resin used, the type of compound containing the cardanol moiety, and the reactive agent. In general, the weight percent ratio of the epoxy resin to the catalyst may be from 0.005 weight % to about 2.0 weight percent. In various embodiments, the weight percent ratio of the epoxy resin to the catalyst may be from 0.005 weight % to about 2.0 weight %, from 0.01 weight % to about 1 .75 weight %, from 0.05 weight % to about 1 .5 weight %, from 0.1 weight % to about 1 .25 weight %, or from 0.5 weight % to about 1 .0 weight %.

[0032] In general, the reaction for preparing the epoxy resin composition may be conducted at a temperature that ranges from about 100°C to about 200°C. In various embodiments, the temperature of the reaction may range from about 100°C to about 200°C, from about 120°C to about 180°C, or from about 130°C to about 170°C. In one embodiment, the temperature of the reaction may be about 140°C to about 160°C. The reaction typically is performed under ambient pressure. The reaction may also be conducted under an inert atmosphere, for example under nitrogen, argon or helium. [0033] The duration of the reaction can and will vary depending many factors, such as the starting substrates, the solvent of the reaction, and the temperature used in the process. Generally, the duration of the reaction may range from about 5 minutes to about 24 hours. In some embodiments, the duration of the reaction may range from about 5 minutes to about 30 minutes, from about 30 minutes to about 2 hours, from about 2 hours to about 4 hours, from about 4 hours to about 10 hours, from about 10 hours to about 15 hours, or from about 15 hours to about 24 hours. In preferred embodiments, the reaction may be allowed to proceed for about 2 hours.

(Hi) structure and properties of the epoxy resin composition

[0034] As shown in the below structures, and not to be limited thereby, the following structures are general chemical structures (l)-(IX) of the epoxy resin composition (ERC) prepared by the reaction of an epoxy resin, a compound containing a cardanol moiety, and a reactive agent comprising a carboxylic acid and/or a phenol with multifunctional hydroxyl groups:

[0035] In addition, in the above chemical structures, R° may be a straight- chain alkyl with 15 carbons containing from 0 to 3 carbon-carbon double bond(s) (C=C) such as for example R° can be selected from -C15H31 , -C15H29, -C15H27, and -C15H25; R¹ can be a bivalent group having 4 carbon atoms of aliphatic structure, (-(CH₂)₄-); and R² and R³ can be ρ,ρ'-isopropylidenebisphenyl structure. [0036] In general, the epoxy resin composition is a liquid at least at 60°C. Additionally, the epoxy resin composition generally exhibits a viscosity of less than about 10,000 mPa-s at 75°C. In some embodiments, the viscosity of the epoxy resin composition may be less than about 8,000 mPa-s at 75°C. In other embodiments, the viscosity of the epoxy resin composition may be less than about 6,000 mPa-s at 75°C.

(b) amino crosslinker compound

[0037] The backer coating composition disclosed herein also comprises an amino crosslinker compound. The amino crosslinker compound may be, for example, amino resins, etherified amino resins, phenolic resins, and mixtures thereof. Non limiting examples of etherified amino crosslinker compounds include lower alkyl ethers (said alkyl groups having from 1 to 8 carbon atoms) of tri- tetra-, penta-, and

hexamethylol melamines, and mixtures thereof. Other non-limiting examples of etherified amino resins may be methylated melamine resin, n-butylated melamine resin, iso-butylated melamine resin, methylated urea resin, n-butylated urea resin, iso- butylated urea resin, or mixture thereof. Preferred embodiments of the amino cross linking compound useful in the present invention composition may include for example hexa(methoxymethyl)-melamine (HMMM) (e.g., CYMEL® 303 available from Allnex and External Chemical).

[0038] In general, the weight percent of the amino crosslinker compound in the composition may range from 6.0 weight % to about 7.0 weight %. In various embodiments, weight percent of the amino crosslinker compound in the composition may range from about 6.0 weight % to about 7.0 weight %, from about 6.2 weight % to about 6.8 weight %, or from 6.4 weight % to about 6.6 weight %. In a preferred embodiment, the weight ratio of the epoxy resin to the amino crosslinker compound used may be about 6.6 weight %. (c) optional additives

[0039] In various embodiments, the backer coating composition may further comprise at least one additive chosen from a curing catalyst, a solvent, a pigment, other additives, or mixtures thereof.

[0040] In some embodiments, a curing catalyst may be added to the backer coating composition of the present invention to speed up the curing process of the backer coating composition. Non-limiting examples of suitable curing catalysts include tris(dimethylaminomethyl)-phenol, bis(dimethylaminomethyl)-phenol, salicylic acid, p-toluenesulfonic acid, dinonylnaphthalene disulfonic acid,

dinonylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, bisphenol A and mixtures thereof. The amount of curing catalyst included in the backer coating composition may range from about 0.05 weight % to about 5 weight % based on the total weight of composition. In various embodiments, the amount of curing catalyst included in the backer coating composition may range from about 0.1 weight % to about 3 weight %, or from about 0.2 weight % to about 1 weight %.

[0041 ] In other embodiments, at least one solvent may be added to the backer coating composition to aid in reducing the viscosity and/or performance parameters of the composition. Solvents useful in the epoxy resin composition may be selected from, for example, ketones, cyclic ketones, ethers, aromatic hydrocarbons, glycol ethers, and combinations thereof. Non-limiting examples of suitable solvents include n-propyl acetate, n-butyl acetate, butyl carbitol acetate, xylenes, o-xylenes, m- xylenes, p-xylenes, (mono) propylene glycol (mono) methyl ether (PM), acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl isobutyl ketone, N-methyl pyrollidone, dimethylformamide, dimethyl sulfoxide, and mixtures thereof. Aromatic solvents such as Solvesso-100 and Solvesso-150, commercially available ExxonMobil Chemical, may also be used as the solvent. Generally, the amount of solvent included in the backer coating composition may range from about 5 weight % to about 50 weight % based on the total weight of composition. In various embodiments, the amount of solvent may be about 5 weight % to 50 weight %, from about 10 weight % to about 40 weight %, or from about 25 weight % to about 35 weight %. [0042] In additional embodiments, the backer coating composition may further comprise one or more pigments and/or other additives which may be useful for the preparation, storage, application, and curing of backer coating compositions.

Suitable additives include fillers, leveling assistants, and the like, or combinations thereof. These optional compounds may include compounds that are normally used in resin formulations known to those skilled in the art for preparing curable compositions and thermosets. In general, the amount of pigment and/or additives included in the backer coating composition may range from about 5 weight % to about 50 weight % based on the total weight of composition. In certain embodiments, the amount of pigment and/or additives may range from about 10 weight % to about 40 weight %, or from about 25 weight % to about 35 weight %.

(d) formation of the backer coating composition

[0043] The backer coating composition may be prepared by forming a reaction mixture comprising an epoxy resin composition, an amino crosslinker compound, and optional additives. These components may be added all at the same time, sequentially, or in any order. The reaction mixture may further comprise at least one optional additive. The backer coating composition may be achieved by blending the above components in any known mixing equipment or reaction vessel until the mixture achieves homogeneity.

[0044] In general, the reaction for preparing the backer coating

composition may be conducted at a temperature that ranges from about 10°C to about 40°C. In various embodiments, the temperature of the reaction may range from about 10°C to about 40°C, from about 15°C to about 35°C, or from about 20°C to about 30°C. In one embodiment, the temperature of the reaction may be about room temperature (~23°C). The reaction typically is performed under ambient pressure. The reaction may also be conducted under an inert atmosphere, for example under nitrogen, argon or helium.

[0045] The duration of the reaction can and will vary depending on many factors, such as the temperature, the method of mixing, and amount of materials being mixed. The duration of the reaction may range from about 5 minutes to about 12 hours. In some embodiments, the duration of the reaction may range from about 5 minutes to about 30 minutes, from about 30 minutes to about 2 hours, from about 2 hours to about 4 hours, from about 4 hours to about 10 hours, or from about 10 hours to about 12 hours. In various embodiments, the preparation may be allowed to continue until the backer coating composition appears to be well mixed.

(e) properties of the backer coating composition

[0046] In general, the backer coating composition, before curing, is a liquid. The backer coating compositions disclosed herein generally exhibit low viscosities (< 300 mPa-s). In various embodiments, the backer coating composition may have a viscosity that ranges from about 100 mPa-s to about 300 mPa-s at about 25°C. In various embodiments, the backer coating composition have a viscosity that ranges from about 100 mPa-s to about 300 mPa-s, from about 125 mPa-s to about 275 mPa-s, from about 150 mPa-s to about 250 mPa-s, or from about 175 mPa-s to about 225 mPa-s at about 25°C. In certain embodiments, the viscosity may range from about 175 mPa-s to about 235 mPa s. at about 25°C.

[0047] Generally, the backer coating composition may comprise a high solid content (e.g., at least 60 weight %). In various embodiments, the backer coating composition may exhibit a solid content from about 68 weight % to about 72 weight %, or from about 69 weight % to about 71 weight %.

[0048] The backer coating compositions disclosed herein generally have low volatile organic compound (VOC) concentrations (e.g., less than about 400 g/L). In certain embodiments, the backer coating composition may have a concentration of volatile organic compound from about 300 g/L to about 400 g/L. In various

embodiments, backer coating composition may have a concentration of volatile organic compound from about 330 g/L to about 390 g/L, or from about 350 g/L to about 370 g/L.

[0049] As a comparison, the Type 9 epoxy resins exhibit properties that are different properties than the backer coating composition of this invention including low solid content (< 50 wt %), higher viscosity (> 450 mPa s), and high concentration of volatile organic compounds (> 420 g/L).

[0050] The backer coating composition, as detailed herein, may be cured by heating the composition. Generally, the temperature necessary to cure the backer coating composition may range from about 100°C to about 300°C. In various embodiments, the curing temperature may range from about 100°C to about 200°C, from about 100°C to about 150°C, from about 150°C to about 200°C, or from about 125°C to about 175°C. In specific embodiments, the curing temperature may be about 150°C.

[0051 ] The duration of curing the backer coating composition can and will vary depending on the type of backer coating composition, the temperature, the humidity, and the thickness of the backer coat. Generally, the duration of curing the backer coating composition may be from 5 minute to 2 hours. In various embodiments, the duration of curing the backer coating composition may be from about 5 minutes to 2 hours, from about 15 minutes to 1.5 hours, or from about 30 minutes to 1 hour. In a specific embodiment, the duration of curing the backer coating composition may be about 30 minutes.

(II) Coated Articles

[0052] Still another aspect of the present disclosure encompasses an article comprising a cured or an uncured backer coating adhering to at least a portion of at least one surface of a substrate. The backer coating adhering to the substrate is prepared by applying a backer coating composition comprising an epoxy resin composition and an amino crosslinker compound to the substrate. The article, in broad terms, may be defined as a material wherein the backer coating composition is initially applied and adheres to at least a portion of at least one surface of the substrate, wherein the backer coating may be cured at a specified temperature such that the backer coating bonds to the substrate. The substrate may be any material that can withstand the curing temperature to form a cured coating. [0053] In various embodiments, the substrate may be a metal. The substrate, as defined herein, may be a single metal or an alloy of various metals. Non- limiting examples of these metals include cast iron, aluminum, tin, brass, steel, copper, zinc aluminum alloy, nickel, or combinations thereof. In a preferred embodiment, the substrate may be steel.

[0054] In various embodiments, the article may be in various

configurations. Non-limiting configuration examples of the article may be a coil, a plate, a sheet, a wire, a tube, or a pipe. The configuration of the article may be of various dimensions, shapes, thicknesses, and weights. In a preferred embodiment, the shape of the article is a coil.

[0055] The backer coating composition may be applied to at least a portion of at least one surface of the article, all of a single surface of the article, on multiple surfaces or sides of the article, over two surfaces of the article, or over every surface of the article. Generally, the backer coating composition may be applied and cured on one layer or multiple layers forming a multi-layered structure. In some embodiments, the backer coating composition may be applied and cured directly on the substrate. In other embodiments, the backer coating composition may be applied to a least one pretreatment layers. After the backer coating composition is cured, at least one other coating may be applied such as a second backer coating.

[0056] In one preferred embodiment, the substrate may be a coil. The coil structure can include a coil backer coating layer directly onto a substrate such as a metal layer. In another embodiment, for example, the coil coating structure can include several layers wherein one of the layers is the cured primer coating layer attached to a metal substrate layer, followed by one or more backer layers. In yet another

embodiment, several layers can be included in-between the backer layer including for example, a first primer coating layer, a first pre-treatment layer, a first zinc (hot-dip galvanizing [HDG]) or zinc-aluminum layer.

[0057] As an illustration of the above embodiment, Figures 1 through 4 show various embodiments of coated plates. However, it should be understood that the present invention is not limited to the embodiments shown in the drawings. [0058] With reference to Figure 1 , there is shown a cross-sectional view of a layered structure, generally indicated by numeral 10, including a primer coating 1 1 adhered to at least a portion of one surface of a substrate such as a metal plate 12. The primer coating layer 1 1 may be directly applied to and adhered onto the substrate such the metal layer 12 as shown in Figure 1 . Any number of other optional layers of various materials can be added to the layered structure of Figure 1 as desired such as one or more layers in between the primer layer 1 1 and the metal layer 12.

[0059] With reference to Figure 2, for example, the backer coating structure can include several layers wherein one of the layers is a primer coating layer 1 1 attached to the metal substrate layer 12, followed by one or more backer layers 21. For example, in the embodiment of Figure 2, there is shown a multi-layered structure, generally indicated by numeral 20, including a primer coating 1 1 sandwiched between the substrate metal plate 12 and the backer coating 21 . In Figure 2, there is shown the primer coating 1 1 adhered to at least a portion of one surface of the metal plate 12, and the backer coating 21 adhered to at least a portion of the surface of the primer coating 1 1 . Any number of other optional layers of various materials can be added to the layered structure of Figure 2 as desired such as one or more layers in between the primer layer 1 1 and the backer coating 21 ; or one or more layers in between the primer coating 1 1 and the metal layer 12.

[0060] With reference to Figure 3, there is shown another embodiment of a cross-sectional view of a multi-layered structure, generally indicated by numeral 30, including a first primer coating 31 a adhered to at least a portion of one surface of the metal plate substrate 12; and a first backer coating 32a adhered to at least a portion of the first primer coating 31 a. The structure 30 also includes a second primer coating 31 b adhered to at least a portion of the other opposite surface of the metal plate substrate 12; and a second backer coating 32b adhered to at least a portion of the first primer coating 31 a. Any number of other optional layers of various materials can be added to the layered structure of Figure 3 as desired such as one or more layers in between the primer layer 31 a or 31 b and the metal layer 12; or one or more layers in between primer layers 31 a or 31 b and the backer layers 32a or 32b, respectively. [0061 ] With reference to Figure 4, other layers commonly used in preparing a final product (e.g., a multi-layer structure, generally indicated by numeral 40) can include for example a first and second pretreatment layers 41 a and 41 b, respectively, formed from by pretreating a first and second zinc layers 42a and 42b, respectively. The first and second zinc layers 42a and 42b may include for example a zinc layer (hot-dip galvanizing [HDG]) or a zinc-aluminum layer adhered to at least a portion of the top and at least a portion of the bottom surfaces (i.e., both surfaces), respectively, of the metal substrate 12. To the surface of the pretreatment layers 41 a and 41 b are zinc layers 42a and 42b, respectively. In the embodiment shown in Figure 4, the primer layers 31 a and 31 b are adhered to the pretreatment layers 41 a and 41 b, respectively. The backer layers 32a and 32b are adhered to the primer layer 31 a and 31 b, respectively. The backer layer 32a is typically referred to as a "topcoat" because this side of the coil product 40 is usually applied on the top side of the final product facing directly at sunlight; and the backer layer 32b is typically referred to as a "backer" because this side of the coil product 40 is usually applied on the back side of the final product 40 facing away or opposite from the sunlight. Any number of other optional layers of various materials can be added to the multi-layered structure of Figure 4 as desired such as one or more layers in between the backer layers 32a or 32b and the primer layers 31 a or 31 b, respectively; or in between the zinc layers 42a or 42b and the metal layer 12, respectively.

[0062] The cured backer composition may exhibit a high adhesion from 3B to 5B. In various embodiments, the cured backer composition may exhibit an adhesion from 3B to about 5B, from about 3B to 4B, or from 4B to 5B. In certain embodiments, the cured backer composition may exhibit an adhesion of approximately 5B.

[0063] Pencil hardness is a measurement of hardness of cured coatings. Generally, the cured backer coating may exhibit a high pencil hardness from 2H to 4H. In various embodiments, the pencil hardness may range from 2H to about 3H, or from about 3H to 4H.

[0064] Another valuable measurement of a cured coating is T-bend flexibility. Generally, the cured backer coating may exhibit a high T-bend flexibility ranging from OT to 2T. In various embodiments, the T-bend flexibility may range from OT to about 1 T, or from 1 T to about 2T. In certain embodiments, the t-bend flexibility may be about OT.

[0065] In each of the cured backer coatings, the methyl ethyl ketone (MEK) resistance is another measurement which shows the chemical resistance of the coating. In certain embodiments, the MEK resistance, measured in double rubs, may range froml O double rubs to 100 double rubs. In other embodiments, the MEK resistance may range from about 10 to 100 double rubs, from about 20 to 80 double rubs, from about 30 to 70 double runs, or from 40 to 60 double rubs. In one

embodiment, MEK resistance, measured in double rubs, may be greater than 50. In another embodiment, the MEK resistance, measured in double rubs, may be about 20.

[0066] Still another measurement of these cured backer coating

compositions is the dried film thickness (DFT). In various embodiments, the cured backer film has a DFT in the range of from 4 micron to about 18 microns. In certain embodiments, the DFT may range from about 4 microns to 18 microns, from about 6 microns to 16 microns, or from about 8 microns to 14 microns. In certain embodiments, the dried film thickness may be about 12 microns.

(Ill) Process for Preparing a Cured Backer Coating

[0067] Another aspect of the present disclosure provides processes for preparing a cured backer coating. The processes comprise providing a curable backer coating composition, which is detailed above in section (I), and heating the curable backer coating composition to a temperature from about 100°C to 300°C to form the cured backer coating. Generally, the curable backer coating composition is applied to at least a portion of a surface of an article to be coated, prior to the heating step of the process.

(a) providing a curable coating composition

[0068] Suitable curable backer coating compositions are described above in section (I). (b) applying the backer coating composition

[0069] The process further comprises applying the curable backer coating composition to a portion of at least one surface of a substrate. Suitable substrates are detailed above in section (II). Application of the curable backer coating composition may be applied through various means. For example, the backer coating composition may be applied using a drawdown bar, a roller, a knife, a paint brush, a sprayer, dipping, or other methods known to the skilled artisan. Also, more than one application of the backer coating composition may be applied forming a multi-layered coating. As detailed above, the curable backer coating composition may be applied to one or more surfaces of the article to be coated.

(c) heating the curable backer coated composition

[0070] The process further comprises heating the curable backer coating composition to a temperature from about 100°C to 300°C to form the cured backer coating. In one embodiment, the curable coil backer composition of present invention can be cured to form a thermoset or cured composition. For example, the curable backer composition of the present invention can be cured under conventional processing conditions to form a film, a coating, or a solid. Curing the curable coil backer composition may be carried out at curing reaction conditions including a predetermined temperature and for a predetermined period of time sufficient to cure the composition. Generally, backer coating composition may be heated to a temperature from about 100°C to about 300°C to form the cured backer coating. In various embodiments, the backer coating composition may be heated to a temperature from about 100°C to about 200°C, from about 100°C to about 150°C, from about 150°C to about 200°C, or from about 125°C to about 175°C. In specific embodiments, the curing temperature may be about 150°C. Methods for heating the substrate may be by a conventional manner or by a method for one skilled in the art. Generally, the duration of heating step may be from 5 minute to 2 hours. In various embodiments, the duration of heating step may be from about 5 minutes to 2 hours, from about 15 minutes to 1 .5 hours, or from about 30 minutes to 1 hour. In a specific embodiment, the duration of the heating step may be about 30 minutes.

(d) properties of the cured backer coating

[0071 ] After the backer coating composition is cured, the resulting cured backer coating may exhibit several beneficial physical properties. In various

embodiments, the resulting cured backer coating exhibits properties including for example a high adhesion, high pencil hardness, a high reverse impact resistance, a high T-bond flexibility, an acceptable MEK resistance.

[0072] The cured backer composition may exhibit a high adhesion from 3B to 5B. In various embodiments, the cured backer composition may exhibit an adhesion from 3B to about 5B, from about 3B to 4B, or from 4B to 5B. In certain embodiments, the cured backer composition may exhibit an adhesion of approximately 5B.

[0073] Pencil hardness is a measurement of hardness of cured coatings. Generally, the cured backer coating may exhibit a high pencil hardness from 2H to 4H. In various embodiments, the pencil hardness may range from 2H to about 3H, or from about 3H to 4H.

[0074] Another valuable measurement of a cured coating is T-bend flexibility. Generally, the cured backer coating may exhibit a high T-bend flexibility ranging from 0T to 2T. In various embodiments, the T-bend flexibility may range from 0T to about 1 T, or from 1 T to about 2T. In certain embodiments, the t-bend flexibility may be about 0T.

[0075] In each of the cured backer coatings, the methyl ethyl ketone (MEK) resistance is another measurement which shows the chemical resistance of the coating. In certain embodiments, the MEK resistance, measured in double rubs, may range from10 double rubs to 100 double rubs. In other embodiments, the MEK resistance may range from about 10 to 100 double rubs, from about 20 to 80 double rubs, from about 30 to 70 double runs, or from 40 to 60 double rubs. In one embodiment, MEK resistance, measured in double rubs, may be greater than 50. In another embodiment, the MEK resistance, measured in double rubs, may be about 20.

[0076] Still another measurement of these cured backer coating

DEFINITIONS

[0077] When introducing elements of the embodiments described herein, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising", "including" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0078] The term "alkyl" as used herein describes saturated hydrocarbyl groups that contain from 1 to 30 carbon atoms. They may be linear, branched, or cyclic, may be substituted as defined below, and include methyl, ethyl, propyl, isopropyl, butyl, hexyl, heptyl, octyl, nonyl, and the like.

[0079] The terms "hydrocarbon" and "hydrocarbyl" as used herein describe organic compounds or radicals consisting exclusively of the elements carbon and hydrogen. These moieties include alkyl, alkenyl, alkynyl, and aryl moieties. These moieties also include alkyl, alkenyl, alkynyl, and aryl moieties substituted with other aliphatic or cyclic hydrocarbon groups, such as alkaryl, alkenaryl and alkynaryl. They may be straight, branched, or cyclic. Unless otherwise indicated, these moieties preferably comprise 1 to 20 carbon atoms.

[0080] The "substituted hydrocarbyl" moieties described herein are hydrocarbyl moieties which are substituted with at least one atom other than carbon, including moieties in which a carbon chain atom is substituted with a heteroatom such as nitrogen, oxygen, silicon, phosphorous, boron, or a halogen atom, and moieties in which the carbon chain comprises additional substituents. These substituents include alkyl, alkoxy, acyl, acyloxy, alkenyl, alkenoxy, aryl, aryloxy, amino, amido, acetal, carbamyl, carbocycio, cyano, ester, ether, halogen, heterocycio, hydroxyl, keto, ketal, phospho, nitro, and thio.

[0081 ] Having described the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.

EXAMPLES

[0074] The following Examples and Comparative Examples further illustrate the present invention in detail but are not to be construed to limit the scope thereof. All parts and percentages are by weight unless otherwise indicated. Various terms, designations and materials used in the following examples are described in the following Table I. The following examples illustrate various embodiments of the invention.

Table I— Raw Materials

Cashew Nutshell Huada Saigao Co., Liquid CNSL RM Cardanol

Ltd

Adipic acid Acid RM Aliphatic dicarboxylic acid Solvay

Sinopharm Co.,

Bisphenol-A Phenol RM Bisphenol-A

Ltd

Dimer Acid Acid RM Dimer fatty acid Yuanda Chemical

RP1619 Polyester Base resin Polyester Nuplex

Cymel 303 Co-reactive Methylated

Allnex agent Hexamethoxymethyl- melamine

Ethyl triphenyl Catalyst Ethyl triphenylphosphonium The Dow Chemical phosphonium acetate Company

acetate

NACURE 2500 Catalyst p-Toluenesulphonic acid King Industries

Titanium Dioxide Pigment Ti0₂ DuPont

Xylene Solvent Xylene Sinopharm Co.,

Ltd

Butyl Carbitol Butyl Carbitol

The Dow Chemical Acetate Solvent Acetate

Company n-Butyl Acetate n-Butyl Acetate Sinopharm Co.,

Solvent

Ltd n-Butanol n-Butanol Sinopharm Co.,

Solvent

Ltd

[0075] Standard measurements, analytical equipment and methods used the Examples were as follows: Viscosity

[0076] Viscosity was measured using a Brookfield CAP-2000+ with a #6 spindle according to the method of ASTM D445 (2010), entitled Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity).

Epoxy Equivalent Weight (EEW)

[0077] EEW was determined by using Mettler Toledo T70 Titrator according to test method of ASTM D1652 (2004), entitled "Standard Test Method for Epoxy Content of Epoxy Resins".

Decomposition Temperature (Td)

[0078] T_d was measured using TGA Q50 of TA Instruments according to the method of IPC-TM-650 (2006), entitled "Decomposition Temperature (T_d) of

Laminate Material Using TGA".

Film Thickness

[0079] The dry film thickness was measured and averaged using the BYKO 4500 dry film thickness gauge manufactured by BYK.

Solvent Resistance: Double Rubs

[0080] According to ASTM D5402 (2006), entitled "Standard Practice for Assessing the Solvent Resistance of Organic Coatings Using Solvent Rubs", methyl ethyl ketone (MEK) was used to determine the solvent resistance. The number of double rubs was recorded when degradation or delamination of the film was observed. Pencil Hardness

[0081 ] Pencil hardness was measured according to the test method of ASTM D3363 (2005), entitled "Standard Test Method for Film Hardness by Pencil Test". The rating scale for hardness ranges from 6B (softer) to 6H (harder).

T-bend Flexibility

[0082] T-bend flexibility was determined according to the method of IS017132 (2007), entitled "Paints and Varnishes - T-Bend Test". The rating scale for T- bend flexibility ranges from OT (high flexibility) to 4T (bad flexibility).

Cross Hatch Adhesion

[0083] Cross hatch adhesion of the coatings was measured according to the procedure described in ASTM D3359 (2009), entitled "Standard Test Methods for Measuring Adhesion by Tape Test" and rated according to the standard described in the procedure. The rating scale for cross hatch adhesion ranges from 5B (good adhesion) to OB (bad adhesion).

Impact Resistance

[0084] The reverse impact resistance of cured film was measured according to ASTM D2794-93 (2010), entitled "Standard Test Method for Resistance of Organic Coatings to the Effects of Rapid Deformation (Impact)". The rating scale for impact resistance ranges from < 1 kg^»cm (brittle) to > 100 kg^»cm (flexible).

General Procedure for Preparing Composition/Cured Product

[0085] The general preparation procedure for preparing a curable composition and a cured product using the composition was as follows: CNSL, dicarboxylic acid or a phenol with two hydroxyl groups and epoxy resin were charged into a reactor with mechanical stirrer and heated to a temperature sufficient to maintain the reaction mixture in a stable condition, for example up to a stable temperature of about 90 °C. Then a catalyst, such as ethyl triphenylphosphonium acetate catalyst, was added into the reactor and mixed with the other ingredients in the reactor. The next step was to raise the temperature in the reactor to a reaction temperature sufficient to drive the reaction mixture, for example, to a reaction temperature of from about 140°C to about 170°C. The reaction mixture was heated slowly, (e.g., at a rate of from 10°C/ 2 minutes) to reach the reaction temperature; and then after a period of curing time for example after about 2 hours of reaction time, the reaction was stopped.

Synthesis Example 1— Preparation of Epoxy Resin Composition (ERC1 )

[0086] 720.0 g D.E.R.383™ epoxy resin, 43.8 g adipic acid and 453.0 g cashew nutshell liquid (CNSL) were charged into a four-neck glass flask equipped with a mechanical stirrer, a condensation tube, and a nitrogen charging adapter. The resulting mixture in the flask was heated slowly. After raising the temperature of the mixture to 130°C slowly, the temperature was held constant for 10 minutes (min). Then, 500 ppm of ethyl triphenylphosphonium acetate (a 70 % solution in methanol) was charged into the flask. The temperature of the resulting reaction mixture was raised to 160°C slowly. The EEW of the reaction mixture was monitored during the reaction. The reaction was stopped after 2 hours (hr). The resultant ERC product (designated herein as "ERC1 ") appeared clear and viscous, and had an EEW of 1 ,068 (g/eq).

Synthesis Example 2— Preparation of Epoxy Resin Composition (ERC2)

[0087] 480.0 g of D.E.R.383™ epoxy resin, 45.6.g of bisphenol-A and

307.6 g of CNSL were charged into a four-neck glass flask equipped with a mechanical stirrer, condensation tube, and a nitrogen charging adapter. The resulting mixture in the flask was heated slowly. After raising the temperature of the mixture to 130°C slowly, the temperature was held constant for 10 min. Then, 500 ppm of ethyl

triphenylphosphonium acetate (a 70 % solution in methanol) was charged into the flask. The temperature of the resulting reaction mixture was raised to 160 °C slowly. The EEW of the reaction mixture was monitored during the reaction. The reaction was stopped after 2 hr. The resultant ERC product (designated herein as "ERC2") appeared clear and viscous, and had an EEW of 990 (g/eq). Synthesis Example 3: Preparation of Epoxy Resin Composition (ERC3)

[0088] 480.0 g of D.E.R.383™ epoxy resin, 1 12.2 g of dimer fatty acid and 307.6 g of CNSL were charged into a four-neck glass flask equipped with a mechanical stirrer, condensation tube, nitrogen charging adapter. The resulting mixture in the flask was heated slowly. After raising the temperature of the mixture to 130 °C slowly, the temperature was held constant for 10 min. Then, 500 ppm of ethyl

tnphenylphosphonium acetate (a 70 % solution in methanol) was charged into the flask. The temperature of the resulting reaction mixture was raised to 160 °C slowly. The EEW of the reaction mixture was monitored during the reaction. The reaction was stopped after 2 hr. The resultant product (designated herein as "ERC3") appeared clear and viscous and had an EEW of 1 , 185 (g/eq).

[0089] Table II shows several properties of Synthesis Example 1 (ERC1 ), Synthesis Example 2 (ERC2), and Synthesis Example 3 (ERC3) epoxy resins compared to a solid epoxy resin (SER): D.E.R. 671™ (a Type 1 epoxy resin and a commercial epoxy product). "Type 1 " to "Type 9" epoxy resins are common epoxy industry terms to characterize epoxy resins based on the molecular weight (MW) of the epoxy resins. ERC1 , ERC2 and ERC3 at 75°C are in the liquid state with viscosities of 8,025; 8250; and 6150, respectively; while the SER D.E.R. 671™ is still in a solid state at 75°C. As indicated in Table II, ERC1 , ERC2 and ERC3 have a lower viscosity than D.E.R. 671 epoxy. Also, advantageously ERC1 , ERC2 and ERC3 exhibit a higher T_d.

Table II— Property Comparison of Epoxy Resins

— no app ica e

Examples 1 -3 and Comparative Examples A— C: Backer Coating Formulation

[0090] The epoxy resin compositions, component (I), of Synthesis Example 1 , Synthesis Example 2 and Synthesis Example 3; and were used for preparing coil backer coating formulations. In addition to the above epoxy resins, a polyester polyol resin (RP1619 Polyester); a commercial epoxy resin D.E.R.669™ epoxy resin; and a blend of the polyester polyol resin (RP1619 Polyester) and

D.E.R.669™ epoxy resin were used to produce backer coating formulations as comparative examples. Each of the above resins was formulated into backer formulation with hexa(methoxymethyl)melamine (Cymel 303) as an amino crossiinker, component (II). Table III describes each of the backer coating formulations.

Table III— Backer Coating Formulations and Properties

[0091 ] In comparison to formulation of Polyester/DER 669 epoxy, polyester, DER 669™ epoxy, formulations with novel epoxy exhibit lower VOC content (lower than 420 g,/ml_), lower viscosity (lower than 300 mPa-s), while prepared high solid content coating (as high as 70 weight %). Particularly, the formulation of DER 669 (Comparative Example C) shows the highest viscosity while the solid content of the formulation is just 53.7%.

Examples 4-6 and Comparative Examples D - F: Coil Backer Coatings

[0092] Backer coatings (i.e., films) were prepared from the above backer coating formulations described in Table III above. To prepare the coating film, the backer coating formulations were cast onto tin plates (tin plate size 10 cm x 15 cm and 0.05 cm thick) by drawing down a coating film on the tin plates with a drawbar, followed by curing the coating film by baking the coating tin plates at 150 °C for 30 minutes. Then, the properties of the resultant film coatings were measured. [0093] The performance of each of the prepared backer coatings was evaluated and the results are described in Table IV.

Table IV— Backer Coating Properties

[0094] Comparing the backer coatings described in Table IV above, the backer coatings of the present invention (Examples 4, 5, 6) exhibit much better PU foam adhesion than the formulations of polyester (Comparative Example D) and the blend of polymers/DER 669™ epoxy (Comparative Example E). Also, the backer coatings of the present invention (Examples 4, 5, 6) exhibit better PU foam adhesion while maintaining a comparable pencil hardness, MEK solvent resistance, and T-Bend flexibility than the other two comparative formulations (Comparative Examples D and E). The polyester film (Comparative Example D) shows a weaker T-Bend flexibility than all other four coating films. Although the DER 669 formulation (Comparative Example F) shows good MEK resistance and high hardness, the T-Bend flexibility is so bad that such formulation would not be suitable for coating applications.

[0095] Among the three backer coatings of the present invention, the backer coatings of Example 4 and 6 made from formulations with ERC 1 and ERC3 show better hardness and MEK solvent resistance than the backer coating of Example 5 made from the formulation with ERC2. All of the backer coatings of the present invention show good T-Bend flexibility and Adhesion to PU.

Claims

CLAIMS What is claimed is:

1 . A coating composition comprising:

(a) an epoxy resin composition at a concentration of about 35 weight percent to about 45 weight percent; and

(b) an amino crosslinker compound.

2. The coating composition of claim 1 , wherein the epoxy resin composition

comprises a reaction product of (i) an epoxy resin, (ii) a compound containing a cardanol moiety, and (iii) a reactive agent selected from a carboxylic acid, a phenolic compound, or mixture thereof.

3. The coating composition of either claims 1 or 2, wherein the epoxy resin

composition has a viscosity of less than about 10,000 mPa-s at 75°C.

4. The coating composition of any of claims 1 to 3, wherein the amino crosslinker compound is an etherified amino resin.

5. The coating composition of claim 4, wherein the etherified amino resin is chosen form methylated melamine resin, n-butylated melamine resin, iso-butylated melamine resin, methylated urea resin, n-butylated urea resin, iso-butylated urea resin, or mixture thereof.

6. The coating composition of any of claims 1 to 5, wherein the amino crosslinker compound has a concentration from about 6 weight percent to about 7 weight percent.

7. The coating composition of any of claims 1 to 6 further comprising at least one agent chosen from a curing catalyst, a solvent, a pigment, or mixture thereof.

8. The coating composition of any one of claims 1 to 7, wherein the composition exhibits a solid content of about 68 weight percent to about 72 weight percent.

9. The coating composition of any one of claims 1 to 8, wherein the composition exhibits a viscosity of less than about 300 mPa-s at 25°C.

10. The coating composition of any one of claims 1 to 9, wherein the composition has a concentration of volatile organic compounds of less than about 400 grams per liter.

1 1 . The coating composition of any one of claims 1 to 10, wherein the composition is cured by heating to a temperature from about 100°C to about 300°C.

12. A process for preparing a cured coating, the process comprising:

(i) providing a curable coating composition comprising (a) about 35 weight percent to about 45 weight percent of an epoxy resin composition and (b) an amino crosslinker compound; and

(ii) heating the curable coating composition to a temperature from about

100°C to about 300°C to form the cured backer coating.

13. The process of claim 12, wherein the epoxy resin composition comprises a

reaction product of (i) an epoxy resin, (ii) a compound containing a cardanol moiety, and (iii) a reactive agent selected from a carboxylic acid, a phenolic compound, or mixture thereof.

14. The process of either claims 12 or 13, wherein the epoxy resin composition has a viscosity of less than about 10,000 mPa-s at 75°C.

15. The process of any of claims 12 to 14, wherein the amino crosslinker compound is an etherified amino resin chosen from methylated melamine resin, n-butylated melamine resin, iso-butylated melamine resin, methylated urea resin, n-butylated urea resin, iso-butylated urea resin, or mixture thereof.

16. The process of any of claims 12 to 15, wherein the amino crosslinker compound has a concentration from about 6 weight percent to about 7 weight percent in the curable coating composition.

17. The process of any of claims 12 to 16, wherein the curable coating composition further comprises at least one agent chosen from a curing catalyst, a solvent, a pigment, or mixture thereof.

18. The process of any of claims 12 to 17, wherein the curable coating composition exhibits a solid content of about 68 weight percent to about 72 weight percent, and a viscosity of less than about 300 mPa-s at 25°C

19. The process of any of claims 12 to 18, wherein the curable coating composition is applied to at least a portion of a surface of a substrate prior to the heating step.

20. The process of claim 19, wherein the substrate is metal.

21 . The process of any of claims 12 to 21 , wherein the cured coating exhibits a T- bend flexibility from about 0T to about 2T.

22. An article comprising a substrate and a coating adhering to at least a portion of a surface of the substrate, wherein the backer coating comprises (a) about 35 weight percent to about 45 weight percent of an epoxy resin composition and (b) an amino crosslinker compound.

23. The article of claim 22, wherein the substrate is metal.

24. The article of either claims 22 or 23, wherein the epoxy resin composition

25. The article of any of claims 22 to 24, wherein the epoxy resin composition has a viscosity of less than about 10,000 mPa-s at 75°C.

26. The article of any of claims 22 to 25, wherein the amino crosslinker compound is an etherified amino resin chosen from methylated melamine resin, n-butylated melamine resin, iso-butylated melamine resin, methylated urea resin, n-butylated urea resin, iso-butylated urea resin, or mixture thereof.

27. The article of any of claims 22 to 26, wherein the amino crosslinker compound has a concentration from about 6 weight percent to about 7 weight percent in the curable coating composition.

28. The article of any of claims 22 to 27, wherein the coating is bonded to the

substrate by heating to a temperature from about 100°C to about 300°.

29. The article of claim 28, wherein the coating exhibits a T-bend flexibility from

about 0T to about 2T.

30. The article of any of claims 22 to 29, further comprising at least one additional coating.