Two-part isocyanate-free primer compositions and methods for providing a primer coating

Abstract

Two-part (2k) isocyanate-free primer composition comprising: a first part comprising a polyester and a melamine formaldehyde resin; and a second part comprising an unblocked acid catalyst, wherein the first part comprises a first portion of the polyester and the second part comprises a second portion of the polyester.

Description

Technical FieldThe art generally relates to two-part primer compositions for coating substrates that are substantially free of isocyanate and curable at low temperatures.BackgroundThe use of two-part or two-part (2k) coating compositions based on a polyisocyanate crosslinking agent and a binder component with functional groups containing active hydrogen is widely used in industrial and vehicle coating because of the very good technological properties of these coating compositions. Such coating compositions are used in both water-based and solvent-based form.Such coating compositions are often cured at an elevated temperature during a time-controlled curing operation. Typically, the component to which the coating composition is applied is processed further after the curing process. Such processing may be performed immediately after the curing process or after a scheduled or unintentional delay. However, coating compositions including isocyanate have been found to continue cross-linking after the curing operation is complete. Thus, the determined level of crosslinking between the components may be different during further processing after the curing process. For example, the coating on a component processed immediately after a curing operation may have less crosslinking than the coating on a component processed one day after the curing operation. Differences in the degree of crosslinking of coatings can result in unevenness in appearance and performance.Further, the continued desire for lightweight vehicles has resulted in both an increase in the use of new materials for automotive components, such as high performance steel, aluminum, plastics, and composites, and an increase in the use of thinner and / or lighter automotive components. Such components often cannot withstand high heat treatment temperatures typically used in curing conventional coatings on conventional automotive components.Accordingly, it is desirable to provide a coating composition, such as a primer composition, that exhibits an improved processing window with less time dependence. It is also desirable to provide a primer composition that is cured at a reduced temperature as compared to conventional coatings, such as at a temperature of less than about 120°C. Moreover, other desirable features and characteristics will become apparent from the following detailed description and the appended claims, taken in conjunction with this background. The prior art is disclosed in the publications DE 39 05 268 A1, DE 195 25 088 A1 and DE 602 04 964 T2.Brief SummaryIn one embodiment of the invention, a two-part (2k) isocyanate-free primer composition is provided. The primer composition includes a first portion comprising a polyester and a melamine formaldehyde resin. The primer composition further includes a second portion comprising an unblocked acid catalyst. The first part comprises a first fraction of the polyester and the second part comprises a second fraction of the polyester. The primer composition is substantially free of isocyanate.In another embodiment, a two-part (2k) isocyanate-free, low temperature curable primer composition is provided and includes a first part comprising a first portion of a crosslinkable component and a melamine as the crosslinking component. The primer composition further includes a second portion comprising a second portion of the crosslinkable component and an unblocked acid catalyst. The composition is curable at a temperature of less than 120°C.Another embodiment provides a method of providing a primer coating on an automotive body component. The method includes mixing a first portion of a two-part (2K) isocyanate-free primer composition comprising polyester and melamine resin with a second portion comprising an unblocked acid catalyst to form a mixed composition. The first part comprises a first fraction of the polyester and the second part comprises a second fraction of the polyester. The method also includes applying the mixed composition to the motor vehicle body component. Further, the method includes curing the mixed composition on the motor vehicle body component at a temperature of less than 120° C.This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.Detailed DescriptionA primer composition for coating a substrate is provided herein, on the one hand according to the features of the main claim 1 and on the other hand according to the features of the dependent claim 10. In embodiments, the substrate is a vehicle, automobile, or automobile. "Vehicle" or "Automobile" or "Automobile" includes an automobile such as a car; van; minivan; bus; sport utility vehicle (SUV); truck; semi-tractor; tractor; motorcycle; trailer; all terrain vehicle (ATV); pick-up; high performance machines such as bulldozers, truck crane, and earthmoving machines; aircraft; boats; ships; and other means of transportation.The primer composition of the present invention is isocyanate-free or substantially free of isocyanate. The terminology "substantially free" in terms of the presence of isocyanate in the primer composition means that the primer composition includes less than 0.1 wt %, alternatively less than 0.05 wt %, alternatively less than 0.01 wt %, alternatively less than 0.005 wt %, or alternatively less than 0.001 wt % isocyanate, based on the total weight of the primer composition.The primer composition of the invention is a two-part, two-part or two-pack coating composition. A "two-part", "two-part", or "two-pack" composition refers to a thermosetting coating composition comprising two components stored in separate containers, which are typically sealed to increase the shelf life of the components of the coating composition. The handling of two component coating compositions generally requires mixing the reactive components just prior to application to avoid premature reaction of the reactive components. The term "just prior to use" is well known to one skilled in the art using two component coating compositions. The period of time during which the ready-to-use coating composition can be prepared prior to actual use / application depends on the pot life of the coating composition. Pot life is the time during which once the reactive components of a coating composition have been mixed, the coating composition can still be properly processed or applied and unaffected quality coatings can be obtained. A sufficiently long pot life is desired to have a convenient time window for preparing / mixing and applying the two component coating compositions. In exemplary embodiments, the primer composition has a pot life of greater than about 20 minutes, such as greater than about 40 minutes, greater than about 60 minutes, greater than about 2 hours, greater than about 4 hours, for example, greater than about 8 hours. In an exemplary embodiment, the pot life of the primer composition is up to about 20 hours.The pot mix is applied as a layer of desired thickness to a substrate surface. After application, the layer dries and cures to form a coating on the substrate surface. A typical two-part coating composition comprises a crosslinkable component and a crosslinking component.Further, a primer composition of the invention is curable at a reduced temperature as compared to conventional primers, such as at a temperature of less than about 120°C (250°F). In an exemplary embodiment, the primer composition is curable at a temperature of less than about 110° C. (230° F.), such as from about 87 ° C. (190° F.) to about 110° C. (230° F.). For example, the primer composition may be heat treated at a temperature of less than about 120° C., such as from about 87 ° C. to about 110 ° C., or from about 100 ° C. to about 110 ° C., in an oven during a curing operation for a selected duration. In an exemplary embodiment, the selected duration is about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 30 minutes, or about 60 minutes.As used herein, "low VOC coating composition" means a coating composition that includes less than 0.6 kilogram of organic solvent (volatile organic component) per liter (5 pounds per gallon), preferably less than 0.53 kilogram (4.4 pounds per gallon) of the composition. The VOC content is determined according to the method provided in ASTM D3960.As used herein, "high solids composition" means a coating composition having a solid component of greater than about 40 percent, such as from about 45 to about 85 percent, for example from about 50 to about 65 percent, each in weight percent based on the total weight of the composition.As used herein, "GPC weight average molecular weight" means a weight average molecular weight measured using gel permeation chromatography. A high performance liquid chromatograph (HPLC) supplied by Hewlett-Packard, Palo Alto, California was used. Unless otherwise stated, the liquid phase used was tetrahydrofuran and the standard was polymethyl methacrylate.As used herein, "Tg" means glass transition temperature. As used herein, "polymer solids" or "binder solids" means a polymer or binder in its dry state.According to one embodiment of the invention, the primer composition of the invention includes a binder having a crosslinkable component and, as a crosslinking component, a melamine. The "crosslinkable component" includes a compound, oligomer, polymer or copolymer having crosslinkable functional groups located in each molecule of the compound, in the oligomer, in the backbone of the polymer, in a side chain of the backbone of the polymer, terminally located on the backbone of the polymer, or a combination thereof. One of ordinary skill in the art would recognize that certain combinations of crosslinkable groups are excluded from the crosslinkable component because, if present, these combinations would crosslink (self-crosslinking) with one another, thereby destroying their ability to crosslink with the crosslinking groups in the crosslinking components defined below.An exemplary crosslinkable component may have an average of from 2 to 25, such as from 2 to 15, for example from 2 to 5, such as from 2 to 3, crosslinkable groups selected from hydroxyl, acetoacetoxy, carboxyl, primary amine, secondary amine, epoxide, anhydride, imino, ketimine, aldimine, or a combination thereof. Exemplary functional crosslinkable groups are hydroxyl and imino functional groups. An exemplary crosslinkable component comprises a polyester.Polyesters having hydroxyl crosslinkable functional groups are suitable for the primer composition. An exemplary polyester has a GPC weight average molecular weight that exceeds 1500, such as from about 1500 to about 100000, for example from about 2000 to about 5000 such as from about 2000 to about 8000, for example from about 2000 to about 5000. The Tg of an exemplary polyester is from about -50° C. to about + 100° C., such as from about -20° C. to about + 50° C.An exemplary polyester may be any conventional solvent soluble polyester conventionally polymerized from suitable polyacids including cycloaliphatic polycarboxylic acids and suitable polyols including polyhydric alcohols. Examples of suitable cycloaliphatic polycarboxylic acids are tetrahydrophthalic acid, hexahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic acid, endomethylenetetrahydrophthalic acid, tricyclodecanedicarboxylic acid, endoethylenehexahydrophthalic acid, camphoric acid, cyclohexanetetracarboxylic acid and cyclobutanetetracarboxylic acid. The cycloaliphatic polycarboxylic acids can be used not only in their cis form, but also in their trans form and as a mixture of the two forms. Examples of suitable polycarboxylic acids which may be used together with the cycloaliphatic polycarboxylic acids if desired are aromatic and aliphatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, halophthalic acids such as tetrachloro- or tetrabromophthalic acid, adipic acid, glutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, trimellitic acid and pyromellitic acid.Suitable polyhydric alcohols include ethylene glycol, propanediols, butanediols, hexanediols, neopentyl glycol, diethylene glycol, cyclohexanediol, cyclohexanedimethanol, trimethylpentanediol, ethylbutylpropanediol, ditrimethylolpropane, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, tris(hydroxyethyl), polyethylene glycol and polypropylene glycol. If desired, monohydric alcohols such as butanol, octanol, lauryl alcohol, ethoxylated or propoxylated phenols may also be included along with polyhydric alcohols.In an exemplary embodiment, the primer composition includes greater than about 10, such as greater than about 15, greater than about 20, such as greater than about 25, such as greater than about 30, for example greater than about 33 weight percent crosslinkable component, e.g., polyester, based on the total weight of the primer composition. In an exemplary embodiment, the primer composition includes less than about 60, such as less than about 50, less than about 45, such as less than about 40, such as less than about 35, for example less than about 34, weight percent crosslinkable component, e.g., polyester, based on the total weight of the primer composition.As used herein, the "cross-linking component" is a component that includes a compound, oligomer, polymer, or copolymer having cross-linking functional groups located in each molecule of the compound, oligomer, backbone of the polymer, in a side chain of the backbone of the polymer, terminally located on the backbone of the polymer, or a combination thereof, which functional groups are capable of cross-linking with the cross-linking functional groups on the cross-linkable component (during the curing step) to produce a coating in the form of cross-linked structures. One of ordinary skill in the art would recognize that certain combinations of crosslinker group / crosslinkable groups are excluded from the embodiments herein, as the combination of crosslinker group / crosslinkable groups would not crosslink and would not produce the film-forming crosslinked structures.An exemplary crosslinker component may be selected from a compound, oligomer, polymer, or copolymer having crosslinking functional groups selected from the group consisting of melamine, amine, ketimine, epoxide, polyacid, anhydride, and a combination thereof. It will be apparent to one of ordinary skill in the art that, in general, certain cross-linking groups of cross-linking components cross-link with certain cross-linking groups of the cross-linking components. Some of these paired combinations include: (1) melamine crosslinking groups generally crosslink with crosslinkable hydroxyl, primary and secondary amine, ketimine or aldimine groups; (2) ketimine crosslinking groups generally crosslink with crosslinkable acetoacetoxy, epoxide or anhydride groups; (3) epoxide crosslinking groups generally crosslink with crosslinkable carboxyl, primary and secondary amine, ketimine or anhydride groups; (4) amine crosslinking groups generally crosslink with crosslinkable acetoacetoxy groups; (5) polyacid crosslinking groups generally crosslink with crosslinkable epoxide groups; and (6) anhydride crosslinking groups generally crosslink with crosslinkable epoxide and ketimine groups. An exemplary crosslinker component is melamine.Melamine formaldehyde resins ("melamines") are well known crosslinking agents for coatings. Melamines can react with hydroxyl functional polymers to form crosslinked coatings. Melamines are commonly used as cross-linking agents in OEM (Original Equipment Manufacturing) coatings for automobiles and light commercial vehicles. These OEM coatings are normally heat treated at high temperatures, such as 130°C (265°F) or above. At ambient temperatures, the reaction between hydroxyl groups and melamine functional groups is extremely slow. Some melamines have amino, more precisely imino, functional groups. Melamines may be fully formylated, so-called fully alkylated melamines. It is known that melamine is not only a crosslinking agent but also promotes adhesion in adhesives. Because of the need to cure at high temperatures, melamine is generally not used in coatings that require curing at lower temperatures.In an exemplary embodiment, melamines are added to a hydroxyl-containing coating composition to provide a resulting coating having improved adhesion and effective pot life. An exemplary melamine has at least one intact hydrogen in the imino group of the melamine, referred to hereinafter as -NH- group, a hydroxyl group, or a combination thereof.Exemplary melamines having at least one -NH- or hydroxyl group include monomeric melamine, polymeric melamine formaldehyde resin, or a combination thereof. The monomeric melamines include low molecular weight melamines containing an average of three or more methylol groups etherified with a C1to C5monovalent alcohol such as methanol, n-butanol or isobutanol per triazine nucleus. Some such suitable monomeric melamines include alkylated melamines such as methylated, butylated, isobutylated melamines and mixtures thereof. Many of these suitable monomeric melamines are commercially available. For example, Cymel ®303, Cymel ®1168, Cymel ®373, Cymel ®370, Cymel ®380, Cymel ®325 or Cymel ®1158 from Cytec Industries, Inc., West Patterson, N.J. may be suitable melamines. Suitable melamine formaldehyde polymeric resins include high imino melamine (partially formylated, -NH).In an exemplary embodiment, the primer composition includes greater than about 5, such as greater than about 10, such as greater than about 15, for example greater than about 18% by weight of the crosslinker component, e.g., melamine, based on the total weight of the primer composition. In an exemplary embodiment, the primer composition includes less than about 30, such as less than about 25, such as less than about 20, for example less than about 19 wt % crosslinker component, e.g., melamine, based on the total weight of the primer composition.In an exemplary embodiment, the primer composition includes melamine formaldehyde resin and butylated melamine formaldehyde resin. In an exemplary embodiment, the primer composition includes greater than about 0.5, such as greater than about 1, such as greater than about 2, for example greater than about 3 wt % melamine formaldehyde resin, based on the total weight of the primer composition. In an exemplary embodiment, the primer composition includes less than about 15, such as less than about 10, such as less than about 5, for example less than about 4%, by weight, of melamine formaldehyde resin, based on the total weight of the primer composition. In an exemplary embodiment, the primer composition includes greater than about 2, such as greater than about 5, such as greater than about 10, for example greater than about 14 wt % butylated melamine formaldehyde resin, based on the total weight of the primer composition. In an exemplary embodiment, the primer composition includes less than about 25, such as less than about 20, such as less than about 18, for example less than about 15 wt % butylated melamine formaldehyde resin, based on the total weight of the primer composition.An exemplary crosslinkable component may comprise from about 1 to about 99, from about 10 to about 50, from about 20 to about 40, or from about 30 to about 35 weight percent of the total solids weight of the primer composition of a polyester having crosslinkable hydroxyl groups, and from about 1 to about 35, from about 5 to about 30, from about 10 to about 25, from about 15 to about 20, or from about 18 to about 19 weight percent of the total solids weight of the primer composition of a melamine having crosslinkable groups selected from a -NH group, a hydroxyl group, or a combination thereof.In an exemplary embodiment, the polyester and the melamine are provided in the primer composition in a polyester:melamine weight ratio of about 0.5:1 to about 5:1, such as about 1:1 to about 3:1, for example about 1.5:1 to about 2:1.In one embodiment, the two-part primer composition includes a first part or component or a second part or component. In an exemplary embodiment, the crosslinker component is included in the first part of the two-part primer composition. Further, a first portion of the crosslinkable component is contained in the first portion of the two-part primer composition. A second portion of the crosslinkable component is contained in the second portion of the two-part primer composition.In an exemplary embodiment, about 1, about 2, about 5, about 10, about 15, about 20, about 25, about 30, about 35, about 40, about 45, about 50, about 55, about 60, about 65, about 70, about 75, about 80, about 85, about 90, about 95, about 98, or about 99% by weight of the crosslinkable component, based on the total weight of the crosslinkable component, is contained in the first portion of the primer composition, while the remainder of the crosslinkable component is contained in the second portion of the primer composition.The second portion of the primer composition further includes a crosslinking catalyst. The crosslinking catalyst is an unblocked acid catalyst. An exemplary unblocked acid catalyst is aromatic sulfonic acid. For example, the unblocked acid catalyst may be dodecylbenzenesulfonic acid (DDBSA). Other suitable unblocked catalysts, such as unblocked acid catalysts, may be used. In an exemplary embodiment, the second portion of the primer composition consists essentially of the unblocked acid catalyst or the unblocked acid catalyst and the second portion of the crosslinkable component. Further, in an exemplary embodiment, the first portion of the primer composition is substantially free of crosslinking catalysts. The terminology "substantially free" regarding the presence of crosslinking catalyst in the first portion of the primer composition means that the first portion of the primer composition includes less than 0.1% by weight, alternatively less than 0.05% by weight, alternatively less than 0.01% by weight, alternatively less than 0.005% by weight, or alternatively less than 0.001% by weight of the crosslinking catalyst, based on the total weight of the primer composition.In an exemplary embodiment, the second portion of the primer composition includes a catalytic amount of the catalyst to accelerate the curing process. The catalytic amount may depend on the reactivity of the primary hydroxyl group of the reactive oligomer present in the hydroxyl component of the binder. In an exemplary embodiment, the primer composition includes about 0.001% to about 5%, such as about 0.01% to 2%, for example about 0.02% to 1%, such as about 0.6%, catalyst, each in weight %, based on the total weight of the primer composition.In an exemplary embodiment, the first portion of the primer composition that can be formulated into high solids coating systems further includes at least one organic solvent. An exemplary organic solvent may be selected from the group consisting of aromatic hydrocarbons such as petroleum naphtha or xylenes; ketones such as methyl amyl ketone, methyl isobutyl ketone, methyl ethyl ketone or acetone; esters such as butyl acetate or hexyl acetate; and glycol ether esters such as propylene glycol monomethyl ether acetate. The amount of organic solvent added will depend on the desired solids content as well as the desired amount of VOC of the composition.In an exemplary embodiment, the first portion of the primer composition may further include at least one alcoholic solvent. An exemplary alcoholic solvent is n-butyl alcohol and / or isobutyl alcohol, although other suitable alcoholic solvents may be used.The first portion of the primer composition may also contain conventional additives well known in the art, such as pigments, stabilizers, rheology control agents, flow agents, toughness improvers, UV preservatives, moisture scavengers and fillers. Such additional additives will, of course, depend upon the intended use of the coating composition. Conductive pigments such as carbon black pigments, conductive graphite, metal particles, or conductive polymers may be added to the coating composition. An exemplary first portion may include a flow additive, such as an acrylic copolymer flow additive, or other acrylic polymers, reactive oligomers, or combinations thereof, as is well known in the coating industry. The first part may also include various pigments, such as in the form of pigment dispersions.The first portion and the second portion may be mixed immediately prior to use or about 5 to 30 minutes prior to use to form a pot mix having a limited pot life. A layer of the pot mix is typically applied to a substrate by conventional techniques such as spraying, electrostatic spraying, roller application, dipping or brush application. The layer of the coating composition then cures at a temperature of less than about 120° C., such as from about 88 to about 110° C., or from about 100 to about 110° C., for a selected duration in the range of from 30 minutes to about 24 hours to form a coating on the substrate having desired coating properties. It will be understood that the actual cure time will depend on the thickness of the coated layer and additional mechanical aids, such as fans, which will help continuously pass air over the coated substrate to speed the cure speed.The primer composition of the present invention can be applied to metallic or nonmetallic substrates. An example of a non-metal substrate includes plastics or composite plastics including SMC, GTX, nylon, melamine and / or acrylic composites, TPO, TPV, polypropylene, PVC, styropor, polycyclopentadiene and the like. By "plastic" is meant any of the usual thermoplastic or thermosetting synthetic non-conductive materials, including thermoplastic olefins such as polyethylene and polypropylene, thermoplastic urethanes, polycarbonates, thermosetting film molding compound, reaction injection molding compound, acrylonitrile-based materials, nylon, and the like.Primer compositions of the invention are particularly useful for forming a primer layer to be coated with one or more other coating layers, such as a basecoat and a subsequent basecoat. The primer composition of the present invention can be used as a primer for OEM vehicle coatings or repair vehicle coatings. The primer composition of the invention can also be used to coat devices or devices having plastic or non-plastic parts thereof, such as, but not limited to, digital devices such as mobile phones, calculators, personal digital assistants (PDAs), desk computers, laptops or tablet computers; home appliances such as microwaves, refrigerators, washing machines and dryers, televisions or telephones; sports equipment; or tools and protective equipment.In a particular embodiment, the primer composition may be characterized as including a first polymer, a second polymer, and a solvent. In embodiments, the first polymer and the second polymer are identified as part of a binder polymer component. The term "binder polymer component" refers to film forming ingredients of a coating composition. Typically, a binder polymer component may comprise polymers, oligomers, and a combination thereof essential for forming a coating having desired properties such as hardness, protection, adhesion, and others. Additional components such as solvents, pigments, catalysts, rheology modifiers, antioxidants, UV stabilizers and absorbers, flow control agents, antifoam agents, anti-cratering agents or other conventional additives are not included in the term. One or more of these additional components may be included in the coating composition. In embodiments and as described in more detail below, the coating composition further includes other components, such as non-functional polymers, crosslinking agents, pigments, and additives.The first polymer includes a first polymer-bonded portion having an acid functional group or derivative thereof. The second polymer includes a second polymer-bonded portion having an amino functional group. The acid functional group and the amino functional group are substantially reactive with each other at least after application of the coating composition to the substrate. The terminology "substantially" in terms of reactivity of the acid-functional group and the amino-functional group with each other means that at least 60, alternatively at least 75, alternatively at least 85, alternatively at least 90, alternatively at least 95, or alternatively at least 99% of the acid-functional groups and the amino-functional groups are reactive with each other. In embodiments, when the first and second polymers are dissolved in a solvent, such as a polar solvent, ionic interactions between the acid functional groups and the amino functional groups are minimized, resulting in a coating composition that exhibits minimal gelling. Also, in embodiments, after evaporation of the solvent, such as after coating the coating composition onto the substrate, the first and second polymers are reactive with each other through ionic interactions between the acid functional groups and the amino functional groups, thereby forming a coating layer that exhibits improved coating performance, such as adhesion, after curing.The first polymer is substantially free of amino functional groups and the second polymer is substantially free of acid functional groups. The terminology "substantially free" in terms of the presence of amino functional groups in the first polymer means that the mixture used to form the first polymer includes less than 0.1 wt %, alternatively less than 0.05 wt %, alternatively less than 0.01 wt %, alternatively less than 0.005 wt %, or alternatively less than 0.001 wt % of amino functional groups based on the total weight of the mixture. The terminology "substantially free" in terms of the presence of the acid functional groups in the second polymer means that the mixture used to form the second polymer includes less than 0.1 wt %, alternatively less than 0.05 wt %, alternatively less than 0.01 wt %, alternatively less than 0.005 wt %, or alternatively less than 0.001 wt % of acid functional groups based on the total weight of the mixture.The first polymer may be used in the coating composition in an amount of from 10 to 90 wt %, alternatively from 10 to 80 wt %, or alternatively from 10 to 60 wt %, based on a total weight of the binder polymer component of the coating composition. The second polymer may be used in the coating composition in an amount of from 10 to 90 wt %, alternatively from 10 to 80 wt %, or alternatively from 10 to 60 wt %, based on a total weight of the binder polymer component of the coating composition. In embodiments, the acid functional groups of the first polymer and the amino functional groups of the second polymer are used in the coating composition in a molar ratio of acid functional groups to amino functional groups of 10:1 to 1:10, alternatively 5:1 to 1:5, or alternatively 4:1 to 1:4.The first polymer includes a first polymer-bonded portion having an acid functional group or derivative thereof. The first polymer-bound portion may be at least a portion of the backbone of the first polymer, may be a side chain of the first polymer, may be grafted to the first polymer, or may be combinations thereof. The first polymer may include more than one first polymer-bonded portion with the polymer-bonded units in any position of the first polymer. In certain embodiments, the first polymer-bonded portion is the first polymer. The first polymer-bonded portion may be formed from an acid-functional monomer, an acid-functional oligomer, or an acid-functional macromonomer. In embodiments, the monomer, oligomer, or macromonomer includes a polymerizable double bond, such as an ethylenically unsaturated double bond. In embodiments, the first polymer is a copolymer. The copolymer may be a random copolymer, an alternating copolymer, a periodic copolymer, a random copolymer, a block copolymer or a graft copolymer. The copolymer may be straight chain or branched.The acid functional group or a derivative thereof may be a carboxylic acid group, sulfonic acid group, phosphoric acid group or an acid anhydride group thereof. The first polymer-bonded portion may have more than one kind of acid functional group or a derivative thereof. In certain embodiments, the acid functional group or derivative thereof is a carboxylic acid group.In embodiments, the first polymer-bound portion is polymerized from a first polymer monomer mixture including acid functional monomers. In certain embodiments, the acid functional monomers are selected from the group of (meth)acrylic acid, crotonic acid, oleic acid, cinnamic acid, glutaconic acid, muconic acid, undecenoic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, and combinations thereof. In embodiments, the first polymeric monomer mixture may include acid anhydrides of any of the acid functional monomers. Suitable acid anhydrides include maleic anhydride and itaconic anhydride. In these embodiments, the acid anhydride monomers can be hydrolyzed to form the corresponding carboxyl groups. It is understood that the first polymeric monomer mixture may include acid functional monomers and acid anhydride monomers.In embodiments, the first polymeric monomer mixture includes the acid functional monomers or derivatives thereof in an amount of from about 0.1 to about 12% by weight, alternatively from about 0.5 to about 10% by weight, alternatively from about 0.5 to about 8% by weight, or alternatively from about 1 to about 5% by weight, based on the total weight of the first polymeric monomer mixture. Without being bound by theory, it is believed that a polymer polymerized from a polymer monomer mixture including acid functional monomers in an amount of greater than 12% by weight results in a coating composition having moisture sensitivity and resulting in gelation of the coating composition due to reactivity with the second polymer. Without being bound by theory, it is also believed that a polymer polymerized from a polymer monomer mixture including acid functional monomers in an amount of less than 0.1 wt % results in a polymer that does not react sufficiently with the second polymer.The first polymer may have a weight average molecular weight at a level of from about 5000 to about 200000, alternatively from about 8000 to about 200000, or alternatively from about 10000 to about 200000. "Molecular weights" disclosed herein can be determined by gel permeation chromatography (GPC) using polystyrene as a standard unless otherwise specified. The first polymer may have a polydispersity at a height of from about 1.05 to about 10.0, alternatively from about 1.2 to about 8, or alternatively from about 1.5 to about 5. The first polymer may have a Tg at a level of from about -5°C to about 100°C, alternatively from about 0°C to 80°C, or alternatively from about 10°C to about 60°C. "Tg" means glass transition temperature of the polymer and may be measured by differential scanning calorimetry (DSC), or may be as described by Fox in Bull. Amer. Physics Soc., 1, 3, page 123 (1956). Without being bound by theory, it is believed that the first polymer having the weight average molecular weight described above provides a coating composition exhibiting minimal gelling and improved coating performance such as improved adhesion. In particular, polymers having a weight average molecular weight of less than 5000 may evaporate from the coating composition prior to reacting with the second polymer and curing. Further, polymers having a weight average molecular weight of greater than 200000 can result in a coating composition having a viscosity that is not suitable for spray application of the coating composition. The first polymer may include one or more polymers each having at least one acid functional group or derivative thereof. Each of the polymers may have more than one kind of acid functional group or derivative thereof.The second polymer includes a second polymer-bonded portion having an amino-functional group. The amino functional group may be a primary amine, a secondary amine, or a tertiary amine. The second polymer-bound portion may be at least a portion of the backbone of the second polymer, may be a side chain of the second polymer, may be grafted to the second polymer, or may be combinations thereof. The second polymer may include more than one second polymer-bonded portion with the polymer-bonded units in any position of the second polymer. In certain embodiments, the second polymer-bonded portion is the second polymer. The second polymer-bonded portion may be formed from an amino-functional monomer, an amino-functional oligomer, or an amino-functional macromonomer. In embodiments, the monomer, oligomer, or macromonomer includes a polymerizable double bond, such as an ethylenically unsaturated double bond. In embodiments, the second polymer is a copolymer. The copolymer may be a random copolymer, an alternating copolymer, a periodic copolymer, a random copolymer, a block copolymer or a graft copolymer. The copolymer may be straight chain or branched.In embodiments, the second polymer-bound portion may be polymerized from a second polymer monomer mixture including amino-functional monomers, carboxyl-functional monomers, or a combination thereof. In one embodiment, the second polymer-bound portion may be polymerized from a second polymer monomer mixture including amino-functional monomers. The amino functional monomers may be selected from the group of t-butylaminoethyl methacrylate (t-BAEMA), N,N-dimethylaminoethyl acrylate (DMAEA), and combinations thereof. In another embodiment, the second polymer-bound portion is polymerized from a second polymer monomer mixture including carboxyl functional monomers. The carboxyl functional monomers can be methacrylic acid. In embodiments, when the second polymer is polymerized from carboxyl functional monomers such as methacrylic acid, the second polymer is reacted with an imine compound such as propylene imine to form primary amino functional groups. Secondary amino functional groups can be polymerized from t-BAEMA. Alternatively, secondary amino functional groups may be polymerized from a polymer including epoxide functional groups and an amino compound such as a primary amine. Tertiary amino functional groups can be polymerized from N,N-dialkylaminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-diethylaminoethyl acrylate, and N,N-dialkylaminoalkyl methacrylate such as N,N-dimethylaminoethyl methacrylate and N,N-diethylaminoethyl methacrylate.In embodiments, the second polymeric monomer mixture includes the amino functional monomers in an amount of from about 0.1 to about 15 wt %, alternatively from about 0.5 to 12 wt %, alternatively from about 0.5 to 10 wt %, or alternatively from about 1 to about 7 wt %, based on the total weight of the second polymeric monomer mixture. Without being bound by theory, it is believed that a polymer polymerized from a polymer monomer mixture including amino functional monomers in an amount of greater than 15 wt % results in gelling of the coating composition due to reactivity with the first polymer. Without being bound by theory, it is also believed that a polymer polymerized from a polymer monomer mixture including amino functional monomers in an amount of less than 0.1 wt % results in a polymer that does not react sufficiently with the second polymer.The second polymer may have a weight average molecular weight at a level of from about 5000 to about 200000, alternatively from about 8000 to about 200000, or alternatively from about 10000 to about 200000. The second polymer may have a polydispersity at a height of from about 1.05 to about 10.0, alternatively from about 1.2 to about 8, or alternatively from about 1.5 to about 5. The second polymer may have a Tgof from about -5°C to about 100°C, alternatively from about 0°C to 80°C, or alternatively from about 10°C to about 60°C. Without being bound by theory, it is believed that the second polymer having the weight average molecular weight described above provides a coating composition exhibiting minimal gelling and improved coating performance such as improved adhesion. In particular, polymers having a weight average molecular weight of less than 5000 may evaporate from the coating composition prior to reacting with the first polymer and curing. Further, polymers having a weight average molecular weight of greater than 200000 can result in a coating composition having a viscosity that is not suitable for spray application of the coating composition. The second polymer may include one or more polymers each having at least one amino-functional group. Each of the polymers may have more than one kind of amino functional group or derivative thereof.In embodiments, the first polymer, the second polymer, or both the first polymer and the second polymer have a crosslinkable functional group. The term "crosslinkable functional group" refers to functional groups located in the oligomer, polymer, backbone of the polymer, pendant of the polymer, terminally on the backbone of the polymer, or combinations thereof, which functional groups are capable of crosslinking with crosslinking functional groups (during the curing step) to form a coating in the form of crosslinked structures. One of ordinary skill in the art would recognize that certain combinations of crosslinkable functional groups are excluded because, if present, these combinations would crosslink (self-crosslinking) with one another, thereby destroying their ability to crosslink with the crosslinking functional groups. A useful combination of crosslinkable functional groups refers to the combinations of crosslinkable functional groups that can be used in coating applications, except for those combinations that would self-crosslink.Typical crosslinkable functional groups may include hydroxyl, thiol, acetoacetoxy, carboxyl, primary amine, secondary amine, epoxide, anhydride, ketimine, aldimine, or an executable combination thereof. Some other functional groups such as ortho ester, ortho carbonate or cyclic amide which can generate hydroxyl or amino groups once the ring structure is opened may also be suitable as crosslinkable functional groups.In certain embodiments, the crosslinkable functional group is a hydroxyl functional group. The hydroxyl functional group may be a primary hydroxyl group, a secondary hydroxyl group, or a combination thereof. The first polymer having the hydroxy functional group may be polymerized from the first polymer monomer mixture further including hydroxyl functional monomers. The second polymer having the hydroxy functional group may be polymerized from the second polymer monomer mixture further including hydroxyl functional monomers. Non-limiting examples of hydroxyl functional monomers used to form primary hydroxyl groups include 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxyethyl acrylate (HEA). Non-limiting examples of hydroxyl functional monomers used to form secondary hydroxyl groups include hydroxypropyl methacrylate (HPMA) and hydroxypropyl acrylate (HPA). In certain embodiments, the hydroxyl functional monomers are selected from the group consisting of 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and combinations thereof. It will be appreciated that the selection of hydroxyl functional groups for the first polymer is independent of the selection of hydroxyl functional groups for the second polymer, and vice versa. In other embodiments, the crosslinkable functional group is a thiol functional group. In various embodiments, only the crosslinkable functional group of the second polymer is the aminofunctional group.In embodiments, the first polymer, the second polymer, or both the first polymer and the second polymer are polymerized from additional monomers, such as any acrylic monomer known in the art, and any ethylenically unsaturated monomer known in the art. Non-limiting examples of these additional monomers include unsubstituted or substituted alkyl acrylates, such as those having from 1 to 20 carbon atoms in the alkyl group; alkyl methacrylates, such as those having from 1 to 20 carbon atoms in the alkyl group; cycloaliphatic acrylates; cycloaliphatic methacrylates; aryl acrylates; aryl methacrylates; other ethylenically unsaturated monomers, such as acrylonitriles, methacrylonitriles, acrylamides, methacrylamides, N-alkylacrylamides, N-alkylmethacrylamides, N,N-dialkylacrylamides, N,N-dialkylmethacrylamides; vinylaromatics, such as styrene, and combinations thereof. Other non-limiting examples include non-functional acrylic monomers such as methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), 2-ethylhexyl methacrylate, isobornyl methacrylate, methacrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (all isomers), 2-ethylhexyl acrylate, isobornyl acrylate, acrylonitrile, and the like. Further non-limiting examples include other ethylenically unsaturated monomers such as vinylaromatics. Non-limiting examples of vinylaromatics include styrene, alpha-methylstyrene, t-butylstyrene, and vinyltoluene. In certain embodiments, the first polymer, the second polymer, or both the first polymer and the second polymer are polymerized from other monomers selected from the group consisting of styrene, methyl (meth)acrylate, butyl (meth)acrylate, ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, and combinations thereof. It will be appreciated that the selection of additional monomers for the first polymer is independent of the selection of additional monomers for the second polymer, and vice versa.In an exemplary embodiment, the first polymer includes the reaction product of styrene, butyl acrylate, isobornyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, and methacrylic acid. The styrene may be used in an amount of from about 10 to about 50 wt %, alternatively from about 20 to about 40 wt %, or alternatively from about 25 to about 35 wt %, based on the total weight of the first polymer. The butyl acrylate may be used in an amount of from about 10 to about 50 wt %, alternatively from about 20 to about 40 wt %, or alternatively from about 25 to about 35 wt %, based on the total weight of the first polymer. The isobornyl acrylate may be used in an amount of from about 1 to about 40 wt %, alternatively from about 10 to about 30 wt %, or alternatively from about 15 to about 25 wt %, based on the total weight of the first polymer. The 2-hydroxyethyl methacrylate may be used in an amount of from about 0.1 to about 30 wt %, alternatively from about 1 to about 20 wt %, or alternatively from about 3 to about 12 wt %, based on the total weight of the first polymer. The hydroxypropyl methacrylate may be used in an amount of from about 0.1 to about 30 wt %, alternatively from about 1 to about 20 wt %, or alternatively from about 3 to about 12 wt %, based on the total weight of the first polymer. The methacrylic acid may be used in an amount of from about 0.1 to about 12% by weight, alternatively from about 1 to about 9% by weight, or alternatively from about 3 to about 7% by weight, based on the total weight of the first polymer.In another exemplary embodiment, the first polymer includes the reaction product of methyl methacrylate, butyl methacrylate, ethylhexyl acrylate, 2-hydroxyethyl methacrylate, and methacrylic acid. The methyl methacrylate may be used in an amount of from about 10 to about 50 wt %, alternatively from about 20 to about 40 wt %, or alternatively from about 25 to about 35 wt %, based on the total weight of the first polymer. The butyl methacrylate may be used in an amount of from about 5 to about 45 wt %, alternatively from about 15 to about 35 wt %, or alternatively from about 20 to about 30 wt %, based on the total weight of the first polymer. The ethylhexyl acrylate can be used in an amount of from about 5 to about 45 wt %, alternatively from about 15 to about 35 wt %, or alternatively from about 20 to about 30 wt %, based on the total weight of the first polymer. The 2-hydroxyethyl methacrylate may be used in an amount of from about 0.1 to about 40 wt %, alternatively from about 10 to about 30 wt %, or alternatively from about 15 to about 25 wt %, based on the total weight of the first polymer. The methacrylic acid may be used in an amount of from about 0.1 to about 12% by weight, alternatively from about 0.1 to about 8% by weight, or alternatively from about 0.1 to about 4% by weight, based on the total weight of the first polymer.In an exemplary embodiment, the second polymer includes the reaction product of methyl methacrylate, butyl acrylate, and t-butylaminoethyl methacrylate. The methyl methacrylate may be used in an amount of from about 60 to about 90 wt %, alternatively from about 70 to about 85 wt %, or alternatively from about 75 to about 81 wt %, each based on a total weight of the second polymer. The butyl acrylate may be used in an amount of from about 5 to about 25 wt %, alternatively from about 10 to about 20 wt %, or alternatively from about 12 to about 18 wt %, each based on a total weight of the second polymer. The t-butylaminoethyl methacrylate may be used in an amount of from about 0.1 to about 12% by weight, alternatively from about 3 to about 10% by weight, or alternatively from about 5 to about 9% by weight, each based on a total weight of the second polymer.In another exemplary embodiment, the second polymer includes the reaction product of methyl methacrylate, ethyl acrylate, and t-butylaminoethyl methacrylate. The methyl methacrylate may be used in an amount of from about 60 to about 90 wt %, alternatively from about 70 to about 85 wt %, or alternatively from about 75 to about 81 wt %, each based on a total weight of the second polymer. The ethyl acrylate may be used in an amount of from about 5 to about 25 wt %, alternatively from about 10 to about 20 wt %, or alternatively from about 12 to about 18 wt %, each based on a total weight of the second polymer. The t-butylaminoethyl methacrylate may be used in an amount of from about 0.1 to about 12% by weight, alternatively from about 3 to about 10% by weight, or alternatively from about 5 to about 9% by weight, each based on a total weight of the second polymer.In another exemplary embodiment, the second polymer includes the reaction product of methyl methacrylate, butyl acrylate, and N,N-dimethylaminoethyl acrylate. The methyl methacrylate may be used in an amount of from about 60 to about 90 wt %, alternatively from about 70 to about 85 wt %, or alternatively from about 75 to about 81 wt %, each based on a total weight of the second polymer. The butyl acrylate may be used in an amount of from about 5 to about 25 wt %, alternatively from about 10 to about 20 wt %, or alternatively from about 12 to about 18 wt %, each based on a total weight of the second polymer. The N,N-dimethylaminoethyl acrylate may be used in an amount of from about 0.1 to about 12% by weight, alternatively from about 3 to about 10% by weight, or alternatively from about 5 to about 9% by weight, each based on a total weight of the second polymer.In another exemplary embodiment, the second polymer includes the reaction product of methyl methacrylate, ethyl acrylate, and the reaction product of methacrylic acid and propyleneimine. The methyl methacrylate may be used in an amount of from about 65 to about 95 wt %, alternatively from about 73 to about 87 wt %, or alternatively from about 77 to about 83 wt %, each based on a total weight of the second polymer. The ethyl acrylate may be used in an amount of from about 5 to about 25 wt %, alternatively from about 10 to about 20 wt %, or alternatively from about 12 to about 18 wt %, each based on a total weight of the second polymer. The methacrylic acid may be used in an amount of from about 0.1 to about 12% by weight, alternatively from about 1 to about 7% by weight, or alternatively from about 2 to about 6% by weight, each based on a total weight of the second polymer. The propylene imine may be used in an amount of from about 0.1 to about 12 wt %, alternatively from about 1 to about 7 wt %, or alternatively from about 1 to about 5 wt %, each based on a total weight of the second polymer.In another exemplary embodiment, the second polymer includes the reaction product of methyl methacrylate, butyl acrylate, 2-hydroxyethyl acrylate, and N,N-dimethylaminoethyl acrylate. The methyl methacrylate may be used in an amount of from about 60 to about 90 wt %, alternatively from about 70 to about 85 wt %, or alternatively from about 75 to about 81 wt %, each based on a total weight of the second polymer. The butyl acrylate may be used in an amount of from about 0.1 to about 15 wt %, alternatively from about 1 to about 15 wt %, or alternatively from about 3 to about 8 wt %, each based on a total weight of the second polymer. The 2-hydroxyethyl acrylate may be used in an amount of from about 0.1 to about 25 wt %, alternatively from about 1 to about 17 wt %, or alternatively from about 7 to about 13 wt %, each based on a total weight of the second polymer. The N,N-dimethylaminoethyl acrylate may be used in an amount of from about 0.1 to about 12% by weight, alternatively from about 1 to about 10% by weight, or alternatively from about 4 to about 10% by weight, based on a total weight of the second polymer.The first polymer, the second polymer, or both the first polymer and the second polymer are independently selected from a straight or branched acrylic polymer, a straight or branched polyester polymer, a polyurethane polymer, or combinations thereof. "Acrylic polymer" means that a polymer comprises polymerized "(Meth)acrylat(e)" which means acrylates and / or methacrylates optionally copolymerized with other ethylenically unsaturated monomers such as acrylamides, methacrylamides, acrylonitriles, methacrylonitriles, and vinylaromatics such as styrene.In embodiments, the first polymer, the second polymer, or both the first polymer and the second polymer may be polyester polymers. The polyester polymer may be straight chain or branched. Useful polyesters may include esterification products of aliphatic or aromatic dicarboxylic acids, polyols, diols, aromatic or aliphatic cyclic anhydrides, and cyclic alcohols. It will be appreciated that the selection of the polyester for the first polymer is independent of the selection of the polyester for the second polymer, and vice versa.Non-limiting examples of suitable cycloaliphatic polycarboxylic acids are tetrahydrophthalic acid, hexahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic acid, endomethylenetetrahydrophthalic acid, tricyclodecanedicarboxylic acid, endoethylenehexahydrophthalic acid, camphoric acid, cyclohexanetetracarboxylic acid and cyclobutanetetracarboxylic acid. The cycloaliphatic polycarboxylic acids can be used not only in their cis form, but also in their trans form and as a mixture of both forms. Further non-limiting examples of suitable polycarboxylic acids may include aromatic and aliphatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, halophthalic acids such as tetrachloro- or tetrabromophthalic acid, adipic acid, glutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, trimellitic acid and pyromellitic acid. Combinations of polyacids such as a combination of polycarboxylic acids and cycloaliphatic polycarboxylic acids may be suitable. Combinations of polyols may also be suitable.Non-limiting suitable polyhydric alcohols include ethylene glycol, propanediols, butanediols, hexanediols, neopentyl glycol, diethylene glycol, cyclohexanediol, cyclohexanedimethanol, trimethylpentanediol, ethylbutylpropanediol, ditrimethylolpropane, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, polyethylene glycol, and polypropylene glycol. If desired, monohydric alcohols such as butanol, octanol, lauryl alcohol, ethoxylated or propoxylated phenols may also be included along with polyhydric alcohols.Non-limiting examples of suitable polyesters include a branched copolyester polymer. The branched copolyester polymer and method of preparation as described in U.S. Pat. No. 6,861,495, which is hereby incorporated by reference, may be suitable. Monomers having multifunctional groups such as ABx(x=1 to 3), including those having one carboxyl group and two hydroxyl groups, two carboxyl groups and one hydroxyl group, one carboxyl group and three hydroxyl groups, or three carboxyl groups and one hydroxyl group, can be used to produce branched structures. Non-limiting examples of such monomers include 2,3-dihydroxypropionic acid, 2,3-dihydroxy-2-methylpropionic acid, 2,2-dihydroxypropionic acid, 2,2-bis(hydroxymethyl)propionic acid, and the like.The branched copolyester polymer can usually be polymerized from a monomer mixture containing a chain extender selected from the group of hydroxycarboxylic acid, a lactone of a hydroxycarboxylic acid, and a combination thereof; and one or more branching monomers. Some of the suitable hydroxycarboxylic acids include glycolic acid, lactic acid, 3-hydroxycarboxylic acids such as 3-hydroxypropionic acid, 3-hydroxybutyric acid, 3-hydroxyvaleric acid and hydroxypivalic acid. Some of the suitable lactones include caprolactone, valerolactone; and lactones of the corresponding hydroxycarboxylic acids such as 3-hydroxypropionic acid, 3-hydroxybutyric acid, 3-hydroxyvaleric acid and hydroxypivalic acid. In certain embodiments, caprolactone is used. In embodiments, the branched copolyester polymer may be prepared by polymerizing the monomer mixture including the chain extender and hyperbranching monomers in one step or by first polymerizing the hyperbranching monomers followed by polymerization of the chain extenders.In embodiments, when the first polymer is a polyester polymer (also referred to herein as "acid functional polyester"), the first polymer may be prepared by using excess amounts of diacid or anhydrides with polyols in the synthesis or other methods known to those skilled in the art to ensure that the polymer chains are terminated with acid functional groups in a straight chain or branched structure. Alternatively, the polyesters having hydroxy groups at the terminal positions of the polymer chain may be further reacted with a diacid or anhydride to form acid functional groups.In embodiments, when the second polymer is a polyester polymer (also referred to herein as an "amino-functional polyester"), the second polymer may be prepared by using an amino-functional polyol, such as a tertiary amino-functional polyol, with polyacids and polyols in the synthesis, or other methods known to those skilled in the art. Non-limiting examples of monomers having only one reactive group capable of condensing with acids or anhydrides and positioning the tertiary amino group at the terminal position of a polymer chain include N,N-dimethylethanolamine, N,N-diethylethanolamine, 1-dimethylamino-2-propanol, 3-dimethylamino-1-propanol, 2-dimethylamino-2-methyl-1-propanol, and the like. Non-limiting examples of polyhydroxys having tertiary amino groups that can position the amino functional groups along the polymer chains include simple compounds such as N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine, N,N-dibutylethanolamine, triethanolamine, triisopropanolamine, and compounds commercially available from Akzo Nobel N.V., Amsterdam, The Netherlands under the trade names Ethomeen ®( a tertiary amine nitrogen atom) and Ethduomeen ®( two tertiary amine nitrogen atoms). The second polymer may also undergo postpolymerization, such as by reacting carboxylic acid-containing polyester polymers as described above with suitable amino compounds, such as propyleneimine.As introduced above, the coating composition further includes a solvent. In embodiments, the solvent is an organic solvent. The organic solvent may be the carrier liquid to disperse and / or dilute the above components and form a coating composition having the desired properties. The solvent or solvent mixtures are typically selected from the group of aromatic hydrocarbons such as petroleum naphtha or xylenes; ketones such as methyl amyl ketone, methyl isobutyl ketone, methyl ethyl ketone or acetone; esters such as butyl acetate or hexyl acetate; glycol ether esters such as propylene glycol monomethyl ether acetate; and alcohols such as isopropanol and butanol, and combinations thereof. The amount of organic solvent added will depend on the desired solids content, rheological (e.g., spray) properties, and the desired amount of VOC of the primer composition. The solvent may be present in an amount of from about 10 to about 95 wt %, alternatively from about 10 to about 50 wt %, or alternatively from about 20 to about 30 wt %, based on a total weight of the primer composition.The total solids content of the primer composition may be in an amount of about 5 to about 90 wt %, alternatively in an amount of about 5 to about 80 wt %, or alternatively in an amount of about 5 to about 60 wt %, based on the total weight of the primer composition.In embodiments, the coating composition is a water-based primer composition. In other embodiments, the primer composition is a solvent-based coating composition. In certain embodiments, the primer composition is substantially free of water. The terminology "substantially free" with respect to the amount of water in the primer composition means that the primer composition includes less than 5 wt %, alternatively less than 3 wt %, alternatively less than 2 wt %, alternatively less than 1 wt %, alternatively less than 0.1 wt % water, based on the total weight of the primer composition.As also introduced above, the primer composition may further include a crosslinking agent that can react with a crosslinkable component to form a crosslinked polymeric network, referred to herein as a crosslinked network. It is understood that the primer composition can provide improved coating performance, particularly adhesion between layers.The term "crosslinking agent" refers to a component having "crosslinking functional groups" which are functional groups located terminally on the backbone of the polymer in each molecule of the compounds, in the oligomer, in the polymer, in the backbone of the polymer, in the pendant group of the polymer, or a combination thereof, which functional groups are capable of crosslinking with crosslinkable functional groups (during the curing step) to form a coating in the form of crosslinked structures. One of ordinary skill in the art would recognize that certain combinations of cross-links and functional groups would be excluded, as these combinations, if present, would cross-link with each other (self-crosslinking), thereby destroying their ability to cross-link with the cross-linked functional groups. A practical combination of crosslinking functional groups refers to the combinations of crosslinking functional groups that can be used in coating applications, except for those combinations that would self-crosslink. One of ordinary skill in the art would recognize that certain combinations of crosslinking functional group and crosslinkable functional groups would be excluded because they would not crosslink and would not produce the film forming crosslinked structures. The coating composition may contain more than one kind of crosslinking agent having the same or different crosslinking functional groups. Typical crosslinking functional groups may include hydroxyl, thiol, acetoacetoxy, carboxyl, primary amine, secondary amine, epoxide, anhydride, ketimine, aldimine, ortho ester, ortho carbonate, cyclic amide, or combinations thereof.In embodiments, melamine compounds having melamine functional groups may be used as crosslinking agents to react with the crosslinkable functional groups such as hydroxyl functional groups and amino functional groups. In certain embodiments, only primary and secondary amino functional groups may be reacted with the melamine functional groups.As also introduced above, the coating composition may further include a pigment. Any pigment known in the art for use in coating compositions may be used in the coating composition. The coating compositions may further contain other additives known in the art for use in coating compositions. Examples of such additives may include UV light stabilizers, wetting agents, anti-wetting and leveling agents, anti-wetting agents based on (meth)acrylic homopolymers; rheology control agents; thickeners such as partially crosslinked polycarboxylic acid or polyurethanes; and anti-foaming agents. The additives may be used in conventional amounts known to those skilled in the art.A method of providing a primer coating on an automotive body component is also provided herein. The method includes the step of mixing a first portion comprising polyester and melamine with a second portion comprising an unblocked acid catalyst to form a mixed composition. Further, the method includes applying the mixed composition to the motor vehicle body component. The method also includes curing the mixed composition on the motor vehicle body component at a temperature of less than about 120° C., such as from about 100 to 110° C. The step of applying may include spraying, electroplating, brush application, roll application, dipping, laminating, and the like.EXAMPLE 1Example 1 describes the composition of the first part and the second part of an exemplary primer composition in Table 1.Weight % of Primer CompositionComponentFirst Part33.298(x)HASS Compatible Polyesters (Crosslinking Component)3,884Melamine formaldehyde resin (crosslinkable component)14,674Butylated melamine formaldehyde resin (crosslinkable component)2,908N-butyl alcohol (solvent)3,683Isobutyl alcohol (solvent)8,303Aromatic hydrocarbon (S-100)16,3Aromatic hydrocarbon (hydrocarbon solvent, S-150)0,249Acrylic copolymer flow additive (additive)1,368HASS Compatible Silica Dispersion (Pigment Dispersion)2,267Black HAPS compatible dispersion (pigment dispersion)1,856HASS compatible talc dispersion (pigment dispersion)4,496White polyester dispersion (pigment dispersion)0,277Brown H.S.HAPS compatible dispersion (pigment dispersion)5,108HASS compatible acrylic dispersion (pigment dispersion)0,717Yellow HASS compatible dispersion (pigment dispersion)Second part33.298(1-x)HASS Compatible Polyesters (Crosslinking Component)0,612Aromatic sulfonic acid (acid crosslinking catalyst)Total total100where 0 ≤ x ≤ 1.

Claims

A two part (2k) isocyanate-free primer composition comprising: a first part comprising a polyester and a melamine formaldehyde resin; and a second part comprising an unblocked acid catalyst, wherein the first part comprises a first portion of the polyester and the second part comprises a second portion of the polyester.The primer composition of claim 1, wherein the second portion consists essentially of the unblocked acid catalyst and the second portion of the polyester.The primer composition of claim 1, wherein the unblocked acid catalyst of the second portion is an aromatic sulfonic acid.The primer composition of claim 1, wherein the unblocked acid catalyst of the second portion is dodecylbenzenesulfonic acid (DDBSA).The primer composition according to claim 1, wherein the primer composition is curable at a temperature of 100 to 110°C.The primer composition of claim 1, wherein the first portion is substantially free of acidic catalyst.The primer composition of claim 1, wherein the first portion further comprises hydrocarbon solvents and alcohol solvents.The primer composition of claim 7, wherein the first portion further comprises at least one pigment and at least one organic solvent.The primer composition of claim 1, wherein the first portion comprises melamine formaldehyde resin and butylated melamine formaldehyde resin, alcohol solvent, aromatic hydrocarbon solvent, flow additive, and pigment.A two part (2k) isocyanate-free, low temperature curable primer composition comprising: a first part comprising a first portion of a crosslinkable component and a melamine as the crosslinking component; and a second part comprising a second portion of the crosslinkable component and an unblocked acid catalyst, wherein the composition is curable at a temperature of less than 120°C.The primer composition of claim 10, wherein the cross-linking component is a melamine formaldehyde resin comprising a monomeric melamine, a polymeric melamine, or any mixture thereof.The primer composition of claim 10, wherein the cross-linking component comprises a melamine formaldehyde resin and a butylated melamine formaldehyde resin.The primer composition of claim 10, wherein the cross-linking component comprises 15 to 20 wt% of the primer composition based on the total weight of the primer composition.The primer composition of claim 10, wherein the crosslinkable component is polyester.The primer composition of claim 14, wherein the polyester comprises from 25 to 50% by weight of the primer composition based on the total weight of the primer composition.The primer composition according to claim 14, wherein the polyester comprises 30 to 40 % by weight of the primer composition based on the total weight of the primer composition.The primer composition of claim 10, wherein the cross-linking component is melamine, wherein the cross-linkable component is polyester, and wherein the polyester and the melamine are provided in a polyester:melamine weight ratio of 1.5:1 to 2:1.The primer composition of claim 10, wherein the unblocked acid catalyst comprises 0.2 to 2% by weight of the primer composition based on the total weight of the primer composition.A method of providing a primer coating on an automotive body component, the method comprising: blending a first portion of a two-part (2K) isocyanate-free primer composition comprising polyester and melamine with a second portion comprising an unblocked acid catalyst, wherein the first portion comprises a first portion of the polyester and the second portion comprises a second portion of the polyester to form a blended composition; applying the blended composition to the automotive body component; and curing the blended composition on the automotive body component at a temperature of less than 120°C.