WO2017087386A1

WO2017087386A1 - Primer coatings

Info

Publication number: WO2017087386A1
Application number: PCT/US2016/062035
Authority: WO
Inventors: Yue Shen; Hongying Chen; Liang Hong
Original assignee: Blue Cube Ip Llc
Priority date: 2015-11-16
Filing date: 2016-11-15
Publication date: 2017-05-26
Also published as: CN108350310A; TW201726826A

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) a blocked polyisocyanate crosslinker compound, process for preparing a cured coating composition, and articles comprising the coating composition.

Description

PRIMER COATINGS

FIELD OF THE INVENTION

[0001 ] The present disclosure generally relates to primer 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 coil primer coatings. Thus, it has been common to use known flexible polyester resins, instead of epoxy resins; and to cure the polyester resins with blocked polyisocyanates to form a cured primer coating. However, primer coatings utilizing a polyester resin exhibit poor anti-corrosion performance as compared to epoxy resin systems.

[0003] Attempts have been made to address the above problems without success. For example, U.S. Patent No. 5,066,757A discloses a one-can heat curable resin composition including: (1 ) a polyester polyol having at least three functional groups; (2) an adduct of an epoxy resin with at least one member selected from the group consisting of an alkanol amine and a monovalent phenol; and (3) a blocked organic polyisocyanate or a blocked prepolymer having terminal NCO groups obtained by reaction of an organic polyisocyanate with an active hydrogen-containing compound. When the above resin composition is used in the production of pre-coated metal, the resulting coating film gives balanced properties, such as chemical resistance, stain resistance, processability and hardness. However, the solid content of the resulting coating is too low (e.g., 50 weight % or less) for some primer coating applications.

Therefore, it would be advantageous to increase the solid content of the curable primer coating composition to higher levels such as 64 weight % or greater. A high solids coating assists in reducing the amount of solvent required in a coating formulation such that the formulation exhibits a viscosity sufficient to allow the formulation to flow and to process the formulation. Such a composition must be prepared carefully and in a controlled manner to provide a useful viscosity resin for coating applications. In turn, reducing the solvent loading of a formulation provides a coating formulation with a lower volatile organic compound (VOC). VOC emission in the coating industry is limited by environmental regulations; and it is beneficial to provide coating formulations with reduced VOC emissions, and coatings made from such formulations, to lessen the impact on the environment.

[0004] Accordingly, it would be beneficial to the industry to provide a curable primer coating composition that can impart to a cured primer coating, made from such curable composition, a balanced combination of increased properties such as a high mechanical strength, a high temperature performance, high flexibility, and a high anticorrosion performance. At the same time, the primer coating composition can release less volatile organic compound (VOC) emissions into the environment. The present invention addresses the above mentioned problems.

SUMMARY OF THE INVENTION

[0005] Among the various aspects of the present disclosure is the provision of a class of primer coating compositions based on an epoxy resin

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

[0006] One aspect of the present disclosure encompasses a coating composition comprising (a) an epoxy resin composition, and (b) a blocked

polyisocyanate crosslinker compound.

[0007] 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) an epoxy resin composition and (b) blocked polyisocyanate crosslinker compound; and heating the curable coating composition to a temperature from about 100°C to about 300°C to form the cured coating.

[0008] 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) an epoxy resin composition, and (b) blocked polyisocyanate crosslinker compound.

[0009] Other features and iterations of the invention are described in more detail below.

BRIEF DESCRIPTION OF DRAWINGS

[0010] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[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 series of three photographs of the F-1 primer coating formulation (see Example 1 ) on a metal plate showing the results of the film's surface property before and after salt-spray testing for 7 days. Panel (A) shows the original coating film with scribes before salt-spray testing; panel (B) shows the coating film after salt-spray testing; and (C) shows the coating film scraped along the scribe to measure the creep value (distance) of corrosion.

[0015] Figure 4 is a series of three photographs of the F-2 primer coating formulation (see Example 2) on a metal plate showing the results of the film's surface property before and after salt-spray testing for 7 days. Panel (A) shows the original coating film with scribes before salt-spray testing; panel (B) shows the coating film after salt-spray testing; and (C) shows the coating film scraped along the scribe to measure the creep value (distance) of corrosion

[0016] Figure 5 is a series of three photographs of the F-3 primer coating formulation (see Example 3) on a metal plate showing the results of the film's surface property before and after salt-spray testing for 7 days. Panel (A) shows the original coating film with scribes before salt-spray testing; panel (B) shows the coating film after salt-spray testing; and (C) shows the coating film scraped along the scribe to measure the creep value (distance) of corrosion.

[0017] Figure 6 is a series of three photographs of the comparative F-A primer coating formulation (see Example F-A) on a metal plate showing the results of the film's surface property before and after salt-spray testing for 7 days. Panel (A) shows the original coating film with scribes before salt-spray testing; panel (B) shows the coating film after salt-spray testing; and panel (C) shows the coating film scraped along the scribe to measure the creep value (distance) of corrosion.

[0018] Figure 7 is a series of three photographs of the F-4 primer coating formulation (see Example 4) on a metal plate showing the results of the film's surface property before and after salt-spray testing for 7 days. Panel (A) shows the original coating film with scribes before salt-spray testing; panel (B) shows the coating film after salt-spray testing; and panel (C) shows the coating film scraped along the scribe to measure the creep value (distance) of corrosion.

[0019] Figure 8 is a series of three photographs of the F-5 primer coating formulation (see Example 5) on a metal plate showing the results of the film's surface property before and after salt-spray testing for 7 days. Panel (A) shows the original coating film with scribes before salt-spray testing; panel (B) shows the coating film after salt-spray testing; and panel (C) shows the coating film scraped along the scribe to measure the creep value (distance) of corrosion.

[0020] Figure 9 is a series of three photographs of the F-6 primer coating formulation (see Example 6) on a metal plate showing the results of the film's surface property before and after salt-spray testing for 7 days. Panel (A) shows the original coating film with scribes before salt-spray testing; panel (B) shows the coating film after salt-spray testing; and panel (C) shows the coating film scraped along the scribe to measure the creep value (distance) of corrosion.

[0021 ] Figure 10 is a series of three photographs of the comparative F-B primer coating formulation (see Example F-B) on a metal plate showing the results of the film's surface property before and after salt-spray testing for 7 days. Panel (A) shows the original coating film with scribes before salt-spray testing; panel (B) shows the coating film after salt-spray testing; and panel (C) shows the coating film scraped along the scribe to measure the creep value (distance) of corrosion.

[0022] Figure 1 1 is a series of three photographs of the comparative F-C primer coating formulation (see Example F-C) on a metal plate showing the results of the film's surface property before and after salt-spray testing for 7 days. Panel (A) shows the original coating film with scribes before salt-spray testing; panel (B) shows the coating film after salt-spray testing; and panel (C) shows the coating film scraped along the scribe to measure the creep value (distance) of corrosion.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present disclosure provides epoxy primer coating compositions comprising an epoxy resin composition and a blocked polyisocyanate crosslinker compound. These primer 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) Primer Coating Compositions

[0024] One aspect of the disclosure provides primer coating compositions comprising an epoxy resin composition and a blocked polyisocyanate crosslinker compound. In general, the primer coating composition is a curable primer coating composition. (a) epoxy resin composition

[0025] 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.

[0026] 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.

[0027] In general, the weight percent of the epoxy resin composition in the primer coating composition may range from 20 weight % to about 40 weight %. In various embodiments, weight percent of the epoxy resin composition may range from about 20 weight % to about 40 weight %, from about 22 weight % to about 38 weight %, from about 26 weight % to about 34 weight %, or from 28 weight % to about 32 weight %. In certain embodiments, the weight percent of the epoxy resin in the primer coating composition may be about 29 weight %.

(i) components of the epoxy resin composition

[0028] 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.

[0029] 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.

[0030] 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.

[0031 ] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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

[0036] 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.

[0037] 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.

[0038] 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 %.

[0039] 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. [0040] 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

[0041 ] 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:

[0042] 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. [0043] In general, the epoxy resin composition is a liquid at least 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) blocked polyisocyanate crosslinker compound

[0044] The primer coating composition disclosed herein also comprises a blocked polyisocyanate crosslinker compound or a blocked prepolymer having a terminal NCO groups obtained by reaction of an organic polyisocyanate with an active hydrogen compound. A key property in utilizing the blocked polyisocyanate compounds may be the deblocking temperature. Generally, the deblocking temperature of the blocked polyisocyanate crosslinker compound used in this disclosure may be under 200° C.

[0045] The blocked polyisocyanate crosslinker compound may be an aliphatic or aromatic blocked polyisocyanate. Non limiting examples of aliphatic blocked polyisocyanate crosslinker compounds include blocked hexamethylene diisocyanate, a blocked isophorone diisocyanate, a blocked methylene dicyclohexyl diisocyanate, or mixtures thereof. The blocked aliphatic diisocyanate may be in a monomeric form or a trimeric form. Non-limiting examples of aromatic blocked polyisocyanate crosslinker compounds include blocked toluenediisocyanate, blocked diphenylmethane-4,4'- diisocyanate, and blocked diphenylmethane-2,4'-diisocyanate. Non-limiting examples of blocked prepolymers having terminal NCO groups may be the prepolymer from the reaction of 1 , 1 , 1 -tris(hydroxymethyl)propane and 2,4-diisocyanatotoluene. In preferred embodiments, the blocked polyisocyanate crosslinker compound may be blocked hexamethylene diisocyanate, blocked isophorone diisocyanate, or mixtures thereof.

[0046] Generally, unblocked polyisocyanates may be too reactive to utilize in a coating composition. A blocking group may be added forming a blocked

polyisocyanate which may react during the curing step to form a coating. Non-limiting examples of suitable blocking groups may be ε-caprolactam, 2-butanone oxime, phenol, or 3, 5-dimethylpyrazole. In certain embodiments, the blocking utilized may be 2- butanone oxime or 3, 5-dimethylpyrazole. Chemical structures (X) and (XI) shown below provide the general structure of the preferred blocking groups.

(X) (XI)

2-butanone oxime 3, 5-dimethylpyrazole

[0047] In general, the weight percent of the blocked polyisocyanate crosshnker compound in the composition may range from 5.0 weight % to about 10.0 weight %. In various embodiments, weight percent of the blocked polyisocyanate crosshnker compound in the composition may range from about 5.0 weight % to about 10.0 weight %, from about 5.4 weight % to about 9.0 weight %, from 5.6 weight % to about 8.0 weight %, or from 6.0 weight % to about 7.0 weight %. In a preferred embodiment, the weight ratio of the epoxy resin to the blocked polyisocyanate crosshnker compound used may be about 6.3 weight %.

(c) optional additives

[0048] In various embodiments, the primer coating composition may further comprise at least one additive chosen from a curing catalyst, a solvent, a pigment, other additives, or mixtures thereof.

[0049] In some embodiments, a curing catalyst may be added to the primer coating composition of the present invention to speed up the curing process of the primer coating composition. Non-limiting examples of suitable curing catalysts include tris(dimethylaminomethyl)-phenol, bis(dimethylaminomethyl)-phenol, salicylic acid, bisphenol A, dibutyltin dilaurate, bismuth tris(2-ethylhexanoate), cobalt bis(2- ethylhexanonate), zinc bis(2-ethylhexanoate), titanium tetra(ethyl acetoacetate), trioctyltin laurate, bis(trioctyltin)oxide, diazabicyclo[2.2.2]octane, 1 ,8- diazabicyclo[5.4.0]undece-1 -ene, diazabicyclononate, tetrabutylphosphonium bicarbonate, and mixtures thereof. The amount of curing catalyst included in the primer coating composition may range from about 0.01 weight % to about 5.0 weight % based on the total weight of composition. In various embodiments, the amount of curing catalyst included in the primer coating composition may range from about 0.01 weight % to about 5.0 weight %, from about 0.05 weight % to about 2.5 weight %, from about 0.1 weight % to about 1 .0 weight %, or from about 0.15 weight % to about 0.25 weight %.

[0050] In other embodiments, at least one solvent may be added to the primer 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, 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 primer 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 %.

[0051 ] In additional embodiments, the primer 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 primer 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 primer 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 primer coating composition

[0052] The primer coating composition may be prepared by forming a reaction mixture comprising an epoxy resin composition, a blocked polyisocyanate 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 primer coating composition may be achieved by blending the above components in any known mixing equipment or reaction vessel until the mixture achieves homogeneity.

[0053] In general, the reaction for preparing the primer 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.

[0054] 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 primer coating composition appears to be well mixed. (e) properties of the primer coating composition

[0055] In general, the primer coating composition, before curing, is a liquid. The primer coating compositions disclosed herein generally exhibit low

viscosities (< 450 mPa-s). In various embodiments, the primer coating composition may have a viscosity that ranges from about 50 mPa-s to about 500 mPa-s at about 25°C. In various embodiments, the primer coating composition have a viscosity that ranges from about 50 mPa-s to about 500 mPa-s, from about 150 mPa-s to about 400 mPa-s, from about 200 mPa-s to about 350 mPa-s, or from about 250 mPa-s to about 300 mPa-s at about 25°C. In certain embodiments, the viscosity may range from about 100 mPa-s to about 130 mPa-s. at about 25°C. In other embodiments, the viscosity may range from about 350 mPa-s to about 425 mPa-s. at about 25°C.

[0056] Generally, the primer coating composition may comprise a high solid content (e.g., at least 60 weight %). In various embodiments, the primer coating composition may exhibit a solid content from about 60 weight % to about 70 weight %, or from about 62 weight % to about 66 weight %.

[0057] The primer coating compositions disclosed herein generally have low volatile organic compound (VOC) concentrations (e.g., less than about 420 g/L). In certain embodiments, the primer coating composition may have a concentration of volatile organic compound from about 380 g/L to about 420 g/L. In various

embodiments, primer coating composition may have a concentration of volatile organic compound from about 390 g/L to about 415 g/L, or from about 400 g/L to about 412 g/L.

[0058] As a comparison, the Type 9 epoxy resins exhibit properties that are different properties than the primer coating composition of this invention including low solid content (< 60 wt %), higher viscosity (> 450 mPa-s), and high concentration of volatile organic compounds (> 420 g/L).

[0059] The primer coating composition, as detailed herein, may be cured by heating the composition. Generally, the temperature necessary to cure the primer 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.

[0060] The duration of curing the primer coating composition can and will vary depending on the type of primer coating composition, the temperature, the humidity, and the thickness of the primer coat. Generally, the duration of curing the primer coating composition may be from 5 minute to 2 hours. In various embodiments, the duration of curing the primer 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 primer coating composition may be about 30 minutes.

(II) Coated Articles

[0061 ] Still another aspect of the present disclosure encompasses an article comprising a cured or an uncured primer coating adhering to at least a portion of at least one surface of a substrate. The primer coating adhering to the substrate is prepared by applying a primer coating composition comprising an epoxy resin

composition and a blocked polyisocyanate crosslinker compound to the substrate. The article, in broad terms, may be defined as a material wherein the primer coating composition is initially applied and adheres to at least a portion of at least one surface of the substrate, wherein the primer coating may be cured at a specified temperature such that the primer coating bonds to the substrate. The substrate may be any material that can withstand the curing temperature to form a cured coating.

[0062] 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.

[0063] 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.

[0064] The primer 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 primer coating composition may be applied and cured on one layer or multiple layers forming a multi-layered structure. In some embodiments, the primer coating composition may be applied and cured directly on the substrate. In other embodiments, the primer coating composition may be applied to a least one

pretreatment layers. After the primer coating composition is cured, at least one other coating may be applied such as a backer or a topcoat.

[0065] In one preferred embodiment, the substrate may be a coil. The coil structure can include a coil primer 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 topcoat or backer layers. In yet another embodiment, several layers can be included in-between the backer layer and the topcoat 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.

[0066] As an illustration of the above embodiment, Figures 1 and 2 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.

[0067] 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. [0068] With reference to Figure 2, for example, the primer 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.

[0069] The cured primer composition may exhibit a high crosscut adhesion from 3B to 5B. In various embodiments, the crosscut adhesion may range from 3B to about 5B, from about 4B to about 5B, or may be greater than 5B. In certain

embodiments, the cross cut adhesion may be about 5B.

[0070] Pencil hardness is a measurement of hardness of cured coatings. Generally, the cured primer coating may exhibits a high pencil hardness from B to 2H. In various embodiments, the pencil hardness may range from B to about 2H, from about HB to H, or from F to H. In certain embodiments, the cured primer coating may exhibit a pencil hardness of HB. In other embodiments, the cured primer coating may exhibit a pencil hardness of H.

[0071 ] In various embodiments, the cured primer coating may exhibit a high reverse impact resistance ranging from about 50 kg. cm to about 150 kg. cm. In various embodiments, the reverse impact resistance may range from about 50 kg. cm to about 150 kg. cm, from about 60 kg. cm to about 140 kg. cm, or from about 75 kg. cm to about 125 kg. cm. In certain embodiments, the cured primer coating may exhibit a reverse impact resistance greater than 100 kg. cm.

[0072] Another valuable measurement of a cured coating is T-bend flexibility. Generally, the cured primer 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 1T, or from 1 T to about 2T.

[0073] Still another measurement of these cured primer coating

compositions is the dried film thickness (DFT). In various embodiments, the cured primer film has a DFT in the range of from 0 micron to about 15 microns. In certain embodiments, the DFT may range from about 0 microns to 15 microns, from about 2.5 microns to 12.5 microns, from about 5 microns to 10 microns, or from about 6 microns to 8 microns.

[0074] One important property exhibited by the cured primer coating is corrosive resistance. This corrosion resistance is determined after spraying a scribed cured primer coating with a salt solution. After a period of time, the film surface properties are evaluated before and after exposure to the salt solution. In one measure which is normally obtained is the creep value, as compared to other commercial coatings. In various embodiments, the creep value of the scribed cured primer coating in this invention may be from 1 mm to about 5 mm. In various embodiments, the creep value may range from 1 .0 mm to about 5.0 mm, from 1 .5 mm to about 4.5mm, from 2.0 mm to about 4.0 mm or from 2.5 mm to about 3.5 mm. As a comparison, the

commercial coatings had a creep value from 2.44 to 6.37 mm. Figures 3 through 1 1 show comparisons of the cured coating formulations before and after salt spray testing for 7 days.

(Ill) Process for Preparing a Cured Primer Coating

[0075] Another aspect of the present disclosure provides processes for preparing a cured primer coating. The processes comprise providing a curable primer coating composition, which is detailed above in section (I), and heating the curable primer coating composition to a temperature from about 100°C to 300°C to form the cured primer coating. Generally, the curable primer 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

[0076] Suitable curable primer coating compositions are described above in section (I).

(b) applying the primer coating composition

[0077] The process further comprises applying the curable primer 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 primer coating composition may be applied through various means. For example, the primer 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 primer coating composition may be applied forming a multi-layered coating. As detailed above, the curable primer coating composition may be applied to one or more surfaces of the article to be coated.

(c) heating the curable primer coated composition

[0078] The process further comprises heating the curable primer coating composition to a temperature from about 100°C to 300°C to form the cured primer coating. In one embodiment, the curable coil primer composition of present invention can be cured to form a thermoset or cured composition. For example, the curable primer 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 primer 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, primer coating composition may be heated to a temperature from about 100°C to about 300°C to form the cured primer coating. In various embodiments, the primer 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 primer coating

[0079] After the primer coating composition is cured, the resulting cured primer coating may exhibit several beneficial physical properties. In various

embodiments, the resulting cured primer 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. In various embodiments, the cured primer composition may exhibit a high crosscut adhesion from 3B to 5B. In other embodiments, the crosscut adhesion may range from 3B to about 5B, from about 4B to about 5B, or may be greater than 5B. In certain embodiments, the cross cut adhesion may be about 5B.

[0080] Pencil hardness is a measurement of hardness of cured coatings. Generally, the cured primer coating may exhibits a high pencil hardness from B to 2H. In various embodiments, the pencil hardness may range from B to about 2H, from about HB to H, or from F to H. In certain embodiments, the cured primer coating may exhibit a pencil hardness of HB. In other embodiments, the cured primer coating may exhibit a pencil hardness of H.

[0081 ] In various embodiments, the cured primer coating may exhibit a high reverse impact resistance ranging from about 50 kg. cm to about 150 kg. cm. In various embodiments, the reverse impact resistance may range from about 50 kg. cm to about 150 kg. cm, from about 60 kg. cm to about 140 kg. cm, or from about 75 kg. cm to about 125 kg. cm. In certain embodiments, the cured primer coating may exhibit a reverse impact resistance greater than 100 kg. cm. [0082] Another valuable measurement of a cured coating is T-bend flexibility. Generally, the cured primer 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.

[0083] Still another measurement of these cured primer coating

[0084] One important property exhibited by the cured primer coating is corrosive resistance. This corrosion resistance is determined after spraying a scribed cured primer coating with a salt solution. After a period of time, the film surface properties are evaluated before and after exposure to the salt solution. In one measure which is normally obtained is the creep value, as compared to other commercial coatings. In various embodiments, the creep value of the scribed cured primer coating in this invention may be from 1 mm to about 5 mm. In various embodiments, the creep value may range from 1 .0 mm to about 5.0 mm, from 1 .5 mm to about 4.5mm, from 2.0 mm to about 4.0 mm or from 2.5 mm to about 3.5 mm. As a comparison, the

DEFINITIONS

[0085] 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. [0086] 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.

[0087] 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.

[0088] 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, carbocyclo, cyano, ester, ether, halogen, heterocyclo, hydroxyl, keto, ketal, phospho, nitro, and thio.

[0089] 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

[0090] The following Examples and Comparative Examples further illustrate various embodiments 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. Table I - Raw Materials

Additive Diisobutylketone

Xylene Solvent Xylene Sinopharm Co., Ltd.

Guangxi Longguang

TALC 400 MESH

Pigment Talcum Talc Development OSMANTHUS BRAND

Co., Ltd.

Propylene Glycol

Propylene Glycol Methyl The Dow Chemical Methyl Ether Acetate Solvent

Ether Acetate Company (MPA)

Solvesso 100 Solvent Aromatic fluid Exxonmobil

Solvesso 150 Solvent Aromatic fluid Exxonmobil

Dibutyltin Dilaurate

Catalyst Dibutyltin Dilaurate (DBTL) Sigma Aldrich (DBTL)

[0091 ] Standard measurements, analytical equipment and methods used in the Examples were as follows:

Viscosity

[0092] 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)

[0093] 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)

[0094] 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

[0095] The dry film thickness was measured and averaged using the BYK 4500 dry film thickness gauge manufactured by BYK.

Solvent Resistance: Double Rubs

[0096] 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

[0097] 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

[0098] 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

[0099] 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

[0100] 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).

Corrosion Resistance Test

[0101 ] Salt spray test was conducted to evaluate corrosion resistance of dry coating film according to the ASTM B1 17-03 Standard practice for operating salt spray (fog) apparatus. Coating panels were taped and scribed after curing, and then placed into the Salt Spray chamber to expose in the fog of 5 weight % NaCI solution. The exposure zone of the salt spray chamber was maintained at about 35°C. The salt spray test was conducted continually for 7 days. The scribe creepage (creep distance) was measured for evaluation.

General Procedure for Preparing Composition/Cured Product

[0102] 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 )

[0103] 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 triphenyl phosphonium 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 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)

[0104] 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, 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 min. Then, 500 ppm of ethyl triphenyl phosphonium 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 "ERC2") appeared clear and viscous, and had an EEW of 990 (g/eq).

Synthesis Example 3: Preparation of Epoxy Resin Composition (ERC3)

[0105] 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 triphenyl

phosphonium acetate (a70 % 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).

[0106] 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 were in the liquid state with viscosities of 8,025 mPa s; 8,250 mPa s; and 6, 150 mPa s, 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

"NA = not applicable Examples 1 -3 and Comparative Examples A

Part A: General Procedure for Preparing Coil Primer Coating Formulations

[0107] In these Examples, a first set of coil primer coating formulations were prepared using Desmodur BL 3575 as a crosslinker. Also, the ERCs, component (a), i.e., Synthesis Example 1 (ERC1 ), Synthesis Example 2 (ERC2) and Synthesis Example 3 (ERC3) were used for preparing the coil primer coating formulations of the present invention including Example 1 (F-1 ), Example 2 (F-2) and Example 3 (F-3). In addition to the above ERC resins, a commercial polyester polyol resin (Dynapol LH 818- 05 Polyester) was used to produce coil primer coating formulation as a comparative example, Comparative Example A (F-A). Each of the above resins was formulated into a coil primer with the blocked polyisocyanate crosslinker (Desmodur BL3575). Table III describes each of the primer coating formulations, F-1 to F-3 and F-A prepared above; and the components of such formulations. The properties of the coil primer coating formulations were also measured and are described in Table III.

[0108] Comparing the formulation properties as described in Table III, the formulations with the advanced epoxy resins, F-1 to F-3, exhibit a lower viscosity and a lower VOC content, while the formulations achieve a higher solid content than the formulation of F-A.

Table III - Primer Coating Formulations and Properties

TIOXIDE LOMON R-706 14.6 14.6 14.6 10.6

TALC 400 MESH OSMANTHUS

14.3 14.3 14.3 10.9 BRAND

Heucophos SAPP 4.6 4.6 4.6 4.0

MIBK 10.3 10.3 10.2 7.0

Propylene Glycol Methyl Ether

10.3 10.3 10.2 0 Acetate (MPA)

Solvesso 100 5.1 5.1 5.1 0

Solvesso 150 5.1 5.1 5.1 7.1

Dibutyltin Dilaurate (DBTL) 0.20 0.20 0.20 0.19

Total 100.0 100.0 100.0 100.0

Properties

Coating Formulation

115 112 130 472 Initial Viscosity, mPa-s

Solid Content, weight % 62.2 62.2 62.2 54.1

VOC, g/L 410.3 410.3 410.3 534.3

[0109] As described in Table III, viscosity values of formulations F-1 to F-3 (Examples 1 -3) were compared with the coil primer coating formulation of Comparative Example A (F-A). Formulations F-1 to F-2 of the present invention have 5-8 weight % higher solid content than formulation F-A, while keeping comparable viscosity. In addition, the VOC of the present invention formulations F-1 to F-3 is 410 g/L (i.e., lower than 420 g/L), while the VOC of the comparative formulation, F-A, is 534 g/L.

Part B: General Procedure for Preparing Coil Primer Coating

[01 10] Coil primer coatings (i.e., films) were prepared from the above primer coating formulations described in Table III above. To prepare the coating film, the coil primer 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. Salt-Spray Testing

[01 1 1 ] An anti-corrosive property exhibited by a coating is a critical property for application of a coil primer coating. Salt-spray testing was employed to measure corrosive resistance of each coil primer coating. Before testing, two perpendicular scribe lines were cut on each coil primer coating film. Then, the coil primer coating panels were kept in a salt-spray box for 7 days. After 7 days, the corrosion damage of each panel was visually inspected. Three pictures were taken of each coil primer coating film as shown in Figures 3-6. Each Figure 3-6 includes three images: (A) the original coating film with scribes before salt-spray testing; (B) the coating film after salt-spray testing; and (C) the coating film scraped along the scribe to measure the creep value (distance) of corrosion.

[01 12] All of the coating films exhibited undesirable red rust on the surface away from the scribes. Corrosion damage, like blister, appeared in the scribe area of each coating. The creep values, the widest length of corrosion along the scribe, were compared and the results are listed in Table IV. Formulations F-1 to F-3 with epoxy had creep values of 5.28, 2.08, and 2.20 mm; while Formulations F-A with polyester had creep values of 6.37 mm and 2.44 mm. The results shown in Table IV suggests primer Formulations F-2 and F-3 with epoxy have a better corrosion resistance than the polyester formulation F-A.

Table IV: Creep Value of Coatings After Salt Spraying

Examples 4-6 and Comparative Examples B-D

Part A: General Procedure for Preparing Coil Primer Coating Formulations

[01 13] In these Examples, a second set of coil primer coating formulations were prepared using Desmodur BL 3175 as a crosslinker. Also, the ERCs, component (a), i.e., Synthesis Example 1 (ERC1 ), Synthesis Example 2 (ERC2) and Synthesis Example 3 (ERC3) were used for preparing the coil primer coating formulations of the present invention including Example 4 (F-4), Example 5 (F-5) and Example 6 (F-6). In addition to the above ERC resins, a commercial polyester polyol resin (Dynapol LH 818- 05 Polyester) was used to produce coil primer coating formulations as comparative examples, Comparative Example B (F-B) and Comparative Example C (F-C). Also, a commercial epoxy resin, DER 669™, was used to prepare a coil primer coating formulation as another comparative example, Comparative Example D (F-D). Each of the above resins was formulated into a coil primer with the blocked polyisocyanate crosslinker (Desmodur BL 3175). Table V describes each of the primer coating formulations of the present invention, F-4 to F-6 and comparative formulations

F-B to F-D prepared above; and the components of such formulations. The properties of the coil primer coating formulations were also measured and are described in Table V.

[01 14] Comparing the properties of the formulations, the formulations with the ERCs exhibit a lower viscosity and a lower VOC content, while the ERCs achieve a higher solid content. In comparison, the DER 669 formulation (F-D) shows the highest viscosity while having the lowest solid content.

Table V - Primer Coating Formulations and Properties

Part B: General Procedure for Preparing Coil Primer Coating

[01 15] Coil primer coatings were prepared from the above primer coating formulations described in Table V above using the general procedure Part B as described in Example 1 above.

[01 16] The performance of each of the prepared primer coatings was evaluated and the results are described in Table VI. As shown in Table VI, primer coatings prepared from ERCs show good adhesion, impact resistance, and T-Bend flexibility as the coating films with polyester and polyester/DER 669™ epoxy. The primer coatings prepared from ERCs showed a lower hardness value than the other coating films. It is theorized that due to the special chemical structure of the ERCs used for the primer coatings of the present invention provides an improved flexibility to the primer coatings. Formulation of DER 669 (F-D) shows a high hardness, but exhibits a very weak T-Bend flexibility (only 2T). T-Bend flexibility is a very important property for a coating to have for the coating to have the capability of being used in coil coating applications. Among three primers with an ERC, the primer with ERC1 shows the highest hardness of H.

Salt-Spray Testing

[01 17] An anti-corrosive property exhibited by a coating is a critical property for application of a coil primer coating. Salt-spray testing was employed to measure corrosive resistance of each coil primer coating. Before testing, two perpendicular scribe lines were cut on each coil primer coating film. Then, the coil primer coating panels were kept in a salt-spray box for 7 days. After 7 days, the corrosion damage of each panel was visually inspected. Three pictures were taken of each coil primer coating film as shown in Figures 7-1 1 . Each Figure 7-1 1 includes three images: (A) the original coating film with scribes before salt-spray testing; (B) the coating film after salt-spray testing; and (C) the coating film scraped along the scribe to measure the creep value (distance) of corrosion. [01 18] All of the coating films exhibited undesirable red rust on the surface away from the scribes. The coating film prepared from Formulation F-B (Comparative Example B) with polyester shows the densest rust marks in comparison to Formulations F-4 to F-6 (Examples 4-5) with epoxy resin. Corrosion damage, like blister, appeared in the scribe area of each coating. The creep values, the widest length of corrosion along the scribe, were compared and the results are listed in Table VII. Formulations F-4 to F-6 with epoxy have creep values of 1 .79, 1 .83, and 1 .00 mm; while Formulations F-B and B-C with polyester is are 6.37 mm and 2.44 mm. The results shown in Table VII suggests primer Formulations F-4, F-5, and F-6 with epoxy have a better corrosion resistance than the polyester formulations F-B and F-C.

Table VII - Creep Value of Coatings After Salt-Spray Testing

Claims

CLAIMS What is claimed is:

1 . A coating composition comprising:

(a) an epoxy resin composition; and

(b) a blocked polyisocyanate 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 epoxy resin

composition has a concentration from about 20 weight percent to about 40 weight percent.

5. The coating composition of any of claims 1 to 4, wherein the blocked

polyisocyanate crosslinker compound is an aliphatic polyisocyanate.

6. The coating composition of claim 5, wherein the aliphatic polyisocyanate is a blocked hexamethylene diisocyanate or a blocked isophorone diisocyanate.

7. The coating composition of any of claims 1 to 6, wherein the blocked

polyisocyanate crosslinker compound has a concentration from about 5 weight percent to about 10 weight percent.

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

9. The coating composition of any one of claims 1 to 8, wherein the composition exhibits a solid content of about 60 weight percent to about 70 weight percent.

10. The coating composition of any one of claims 1 to 9, wherein the composition exhibits a viscosity of less than about 450 mPa-s at 25°C.

1 1 . The coating composition of any one of claims 1 to 10, wherein the composition has a concentration of volatile organic compounds of less than about 420 grams per liter.

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

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

(i) providing a curable coating composition comprising (a) an epoxy resin composition and (b) a blocked polyisocyanate crosslinker compound; and

(ii) heating the curable coating composition to a temperature from about 100°C to about 300°C to form the cured primer coating.

14. The process of claim 13, 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.

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

16. The process of any of claims 13 to 15, wherein the blocked polyisocyanate

crosslinker compound is an aliphatic polyisocyanate.

17. The process of claim 16, wherein the aliphatic polyisocyanate is a blocked

hexamethylene diisocyanate or a blocked isophorone diisocyanate.

18. The process of any of claims 13 to 17, wherein the epoxy resin composition has a concentration from about 20 weight percent to about 40 weight percent, and the blocked polyisocyanate crosslinker compound has a concentration from about 5 weight percent to about 10 weight percent.

19. The process of any of claims 13 to 18, wherein the curable coating composition further comprises at least one agent chosen from a curing catalyst, a solvent, a pigment, or mixture thereof.

20. The process of any of claims 13 to 19, wherein the curable coating composition exhibits a solid content of about 60 weight percent to about 70 weight percent, and a viscosity of less than about 450 mPa-s at 25°C.

21 . The process of any of claims 13 to 20, wherein the curable coating composition is applied to at least a portion of a surface of a substrate prior to the heating step.

22. The process of claim 21 , wherein the substrate is metal.

23. The process of any of claims 13 to 22, wherein the cured coating exhibits a T- bend flexibility from about 0T to about 2T.

24. The process of any of claims 13 to 23, wherein the cured coating exhibits a

corrosion resistance measured in terms of creep value in scribe area of from about 1 mm to about 5 mm.

25. An article comprising a substrate and a coating adhering to at least a portion of a surface of the substrate, wherein the coating comprises (a) an epoxy resin composition and (b) a blocked polyisocyanate crosslinker compound.

26. The article of claim 25, wherein the substrate is metal.

27. The article of either claims 25 or 26, wherein the epoxy resin composition

28. The article of any of claims 25 to 27, wherein the epoxy resin composition has a viscosity of less than about 10,000 mPa-s at 75°C.

29. The article of any of claims 25 to 28, wherein the blocked polyisocyanate

crosslinker compound is an aliphatic polyisocyanate.

30. The article of claim 29, wherein the aliphatic polyisocyanate is a blocked

hexamethylene diisocyanate or a blocked isophorone diisocyanate.

31 . The article of any of claims 25 to 30, wherein the epoxy resin composition has a concentration from about 20 weight percent to about 40 weight percent, and the blocked polyisocyanate crosslinker compound has a concentration from about 5 weight percent to about 10 weight percent.

32. The article of any of claims 25 to 31 , wherein the coating is bonded to the

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

33. The article of claim 32, wherein the coating exhibits a T-bend flexibility from about 0T to about 2T.

34. The article of either claims 32 or 33, wherein the coating exhibits a corrosion resistance measured in terms of creep value in scribe area of from about 1 mm to about 5 mm.

35. The article of any of claims 25 to 34, further comprising a least one additional coating.