Coated substrates prepared with waterborne sealer and primer compositions

FIELD OF THE INVENTION

0001The present invention relates to multilayer coated substrates prepared with waterborne sealer and primer compositions.

BACKGROUND OF THE INVENTION

0002In the automotive refinish industry, a typical multilayer coating stack applied to a substrate includes a solventborne primer, a solventborne sealer, and one or more aesthetic topcoats. The substrate and each applied coating layer are usually sanded between applications for adhesion and appearance purposes. For the sake of convenience it is desired that each coating dry and/or cure to an extent that it may be sandable within fifteen minutes of application. Each coating is also designed to provide high film build with a minimum of coating layers, yielding smoothness and leveling with no pops or pinholes. As new regulations continue to compel coatings manufacturers to reduce emissions, challenges arise in designing environmentally friendly refinish coatings with comparable properties to their solventborne predecessors.

0003It would be desirable to provide waterborne sealer and primer compositions that may be used to prepare multilayer coated substrates, with properties similar to their solventborne counterparts.

SUMMARY OF THE INVENTION

0004The present invention is directed to a multilayer coated substrate according to claim 1.

DETAILED DESCRIPTION OF THE INVENTION

0005Other than in the operating examples, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, times and temperatures of reaction, ratios of amounts, values for molecular weight (whether number average molecular weight ("M_n") or weight average molecular weight ("M_w")), and others in the following portion of the specification may be read as if prefaced by the word "about" even though the term "about" may not expressly appear with the value, amount or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

0006Also for molecular weights, whether number average (M_n) or weight average (M_w), these quantities are determined by gel permeation chromatography using polystyrene as standards as is well known to those skilled in the art and such as is discussed in <patcit id="pcit0001" dnum="US4739019A"><text>U.S. Patent No. 4,739,019</text></patcit>, at column 4, lines 2-45.

0007Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used.

0008Plural referents as used herein encompass singular and vice versa. For example, while the invention has been described in terms of "a" cationic acrylic resin derived from an epoxy functional acrylic resin, a plurality, including a mixture of such resins can be used.

0009Any numeric references to amounts, unless otherwise specified, are "by weight". The term "equivalent weight" is a calculated value based on the relative amounts of the various ingredients used in making the specified material and is based on the solids of the specified material. The relative amounts are those that result in the theoretical weight in grams of the material, like a polymer, produced from the ingredients and give a theoretical. number of the particular functional group that is present in the resulting polymer. The theoretical polymer weight is divided by the theoretical number of equivalents of functional groups to give the equivalent weight. For example, urethane equivalent weight is based on the equivalents of urethane groups in the polyurethane material.

0010As used in the following description and claims, the following terms have the meanings indicated below: As used herein, the term "polymer" is meant to refer to prepolymers, oligomers and both homopolymers and copolymers; the prefix "poly" refers to two or more. By "composite material" is meant a combination of two or more differing materials.

0011As used herein "based on the total weight of resin solids" or "based on the total weight of organic binder solids" (used interchangeably) of the composition means that the amount of the component added during the formation of the composition is based upon the total weight of the resin solids (non-volatiles) of the film forming materials, including crosslinkers and polymers present during the formation of the composition, but not including any water, solvent, or any additive solids such as hindered amine stabilizers, photoinitiators, pigments including extender pigments and fillers, flow modifiers, catalysts, and UV light absorbers.

0012As used herein, the terms "thermosetting" and "curable" can be used interchangeably and refer to resins that "set" irreversibly upon curing or crosslinking, wherein the polymer chains of the polymeric components are joined together by covalent bonds. This property is usually associated with a crosslinking reaction of the composition constituents often induced, for example, by heat or radiation. See <nplcit id="ncit0001" npl-type="b"><text>Hawley, Gessner G., The Condensed Chemical Dictionary, Ninth Edition., page 856</text></nplcit>; <nplcit id="ncit0002" npl-type="b"><text>Surface Coatings, vol. 2, Oil and Colour Chemists' Association, Australia, TAFE Educational Books (1974</text></nplcit>). Curing or crosslinking reactions also may be carried out under ambient conditions. By ambient conditions is meant that the coating undergoes a thermosetting reaction without the aid of heat or other energy, for example, without baking in an oven, use of forced air, or the like. Usually ambient temperature ranges from 60 to 90 °F (15.6 to 32.2 °C), such as a typical room temperature, 72°F (22.2°C). Once cured or crosslinked, a thermosetting resin will not melt upon the application of heat and is insoluble in solvents. As used in this specification and the appended claims, the articles "a," "an," and "the" include plural referents, and are used interchangeably with the terms "at least one" and "one or more", unless expressly and unequivocally limited to one referent.

0013The various examples of the present invention as presented herein are each understood to be non-limiting with respect to the scope of the invention.

0014The term "reactive" refers to a functional group capable of undergoing a chemical reaction with itself and/or other functional groups spontaneously or upon the application of heat or in the presence of a catalyst or by any other means known to those skilled in the art.

0015By "essentially free" of a material is meant that a composition has only trace or incidental amounts of a given material, and that the material is not present in an amount sufficient to affect any properties of the composition. These materials are not essential to the composition and hence the composition is free of these materials in any appreciable or essential amount. If they are present, it is in incidental amounts only, typically less than 0.1 percent by weight, based on the total weight of solids in the composition.

0016The multilayer coated substrates of the present invention is defined according to claim 1.

0017Non-metallic substrates A) include polymeric, plastic, polyester, polyolefin, polyamide, cellulosic, polystyrene, polyacrylic, poly(ethylene naphthalate), polypropylene, polyethylene, nylon, EVOH, poly(lactic acid), other "green" polymeric substrates, poly(ethylene terephthalate) ("PET"), polycarbonate, polycarbonate acrylonitrile butadiene styrene ("PC/ABS"), polyamide, polymer composites and the like. Car parts typically formed from thermoplastic and thermoset materials include bumpers and trim.

0018The metal substrates used in the present invention include ferrous metals, non-ferrous metals and combinations thereof. Suitable ferrous metals include iron, steel, and alloys thereof. Non-limiting examples of useful steel materials include cold rolled steel, pickled steel, steel surface-treated with any of zinc metal, zinc compounds and zinc alloys (including electrogalvanized steel, hot-dipped galvanized steel, GALVANNEAL steel, and steel plated with zinc alloy,) and/or zinc-iron alloys. Also, aluminum, aluminum alloys, zinc-aluminum alloys such as GALFAN, GALVALUME, aluminum plated steel and aluminum alloy plated steel substrates may be used, as well as magnesium metal, titanium metal, and alloys thereof. Steel substrates (such as cold rolled steel or any of the steel substrates listed above) coated with a weldable, zinc-rich or iron phosphide-rich organic coating are also suitable for use in the present invention. Such weldable coating compositions are disclosed in <patcit id="pcit0002" dnum="US4157924A"><text>U. S. Patent Nos. 4,157,924</text></patcit> and <patcit id="pcit0003" dnum="US4186036A"><text>4,186,036</text></patcit>. Cold rolled steel is also suitable when pretreated with an appropriate solution known in the art, such as a metal phosphate solution, an aqueous solution containing at least one Group IIIB or IVB metal, an organophosphate solution, an organophosphonate solution, and combinations thereof, as discussed below.

0019The substrate may alternatively comprise more than one metal or metal alloy in that the substrate may be a combination of two or more metal substrates assembled together such as hot-dipped galvanized steel assembled with aluminum substrates. The substrate may alternatively comprise a composite material such as a fiberglass composite. It is desirable to have a coating system which can be applied to both metal and non-metal parts. The substrate may comprise part of a vehicle. "Vehicle" is used herein in its broadest sense and includes all types of vehicles, such as but not limited to airplanes, helicopters, cars, trucks, buses, vans, golf carts, motorcycles, bicycles, railroad cars, tanks and the like. It will be appreciated that the portion of the vehicle that is coated according to the present invention may vary depending on why the coating is being used.

0020The shape of the substrate can be in the form of a sheet, plate, bar, rod or any shape desired, but it is usually in the form of an automobile part, such as a body, door, fender, hood or bumper. The thickness of the substrate can vary as desired.

0021The substrates to be used may be bare substrates. By "bare" is meant a virgin substrate that has not been treated with (or has been stripped of) any pretreatment compositions such as conventional phosphating baths, heavy metal rinses, etc. Additionally, bare metal substrates being used in the present invention may be a cut edge of a substrate that is otherwise treated and/or coated over the rest of its surface. Alternatively, the substrates may undergo one or more treatment steps known in the art prior to the application of the curable film-forming composition.

0022Before depositing any coating compositions upon the surface of the substrate, it is common practice, though not necessary, to remove foreign matter or previously applied paints such as OEM coatings from the surface by thoroughly stripping, cleaning and degreasing the surface. When the substrate is not an existing vehicle part, such cleaning typically takes place after forming the substrate (stamping, welding, etc.) into an end-use shape. The surface of the substrate can be cleaned by physical or chemical means, or both, such as mechanically abrading the surface (e. g., sanding) or cleaning/degreasing with commercially available alkaline or acidic cleaning agents which are well known to those skilled in the art, such as sodium metasilicate and sodium hydroxide. A non-limiting example of a cleaning agent is CHEMKLEEN 163, an alkaline-based cleaner commercially available from PPG Industries, Inc.

0023In an OEM setting, a metal substrate may optionally be pretreated with any suitable solution known in the art, such as a metal phosphate solution, an aqueous solution containing at least one Group IIIB or IVB metal, an organophosphate solution, an organophosphonate solution, and combinations thereof. The pretreatment solutions may be essentially free of environmentally detrimental heavy metals such as chromium and nickel. Suitable phosphate conversion coating compositions may be any of those known in the art that are free of heavy metals. Examples include zinc phosphate, which is used most often, iron phosphate, manganese phosphate, calcium phosphate, magnesium phosphate, cobalt phosphate, zinc-iron phosphate, zinc-manganese phosphate, zinc-calcium phosphate, and layers of other types, which may contain one or more multivalent cations. Phosphating compositions are known to those skilled in the art and are described in <patcit id="pcit0004" dnum="US4941930A"><text>U. S. Patents 4,941,930</text></patcit>, <patcit id="pcit0005" dnum="US5238506A"><text>5,238,506</text></patcit>, and <patcit id="pcit0006" dnum="US5653790A"><text>5,653,790</text></patcit>.

0024The IIIB or IVB transition metals and rare earth metals referred to herein are those elements included in such groups in the CAS Periodic Table of the Elements as is shown, for example, in the<nplcit id="ncit0003" npl-type="b"><text> Handbook of Chemistry and Physics, 63rd Edition (1983</text></nplcit>).

0025Typical group IIIB and IVB transition metal compounds and rare earth metal compounds are compounds of zirconium, titanium, hafnium, yttrium and cerium and mixtures thereof. Typical zirconium compounds may be selected from hexafluorozirconic acid, alkali metal and ammonium salts thereof, ammonium zirconium carbonate, zirconyl nitrate, zirconium carboxylates and zirconium hydroxy carboxylates such as hydrofluorozirconic acid, zirconium acetate, zirconium oxalate, ammonium zirconium glycolate, ammonium zirconium lactate, ammonium zirconium citrate, and mixtures thereof. Hexafluorozirconic acid is used most often. An example of a titanium compound is fluorotitanic acid and its salts. An example of a hafnium compound is hafnium nitrate. An example of a yttrium compound is yttrium nitrate. An example of a cerium compound is cerous nitrate.

0026Typical compositions to be used in the pretreatment step include nonconductive organophosphate and organophosphonate pretreatment compositions such as those disclosed in <patcit id="pcit0007" dnum="US5294265A"><text>U. S. Patents 5,294,265</text></patcit> and <patcit id="pcit0008" dnum="US5306526A"><text>5,306,526</text></patcit>. Such organophosphate or organophosphonate pretreatments are available commercially from PPG Industries, Inc. under the name NUPAL^®.A repair primer coating is conventionally applied to a substrate in several application layers with a total dry film thickness around 100 to 150 microns. The purpose of the primer layer is to even out slight underlayer thickness variations that are created when the original Class A surface is partially sanded, causing a gradient of film thicknesses on top of which the repair layering system is applied. To provide this even surface, a significant portion of the thickness of the primer may be removed during the sanding step (circa. 50%). Significantly more importance is therefore placed on the ability to attain 50 micron dry film thickness per application step and the sanding properties of the primer, rather than on the smoothness of the primer itself.

0027In contrast, the purpose of applying a sealer over a repair area is to provide a smooth and consistent surface on top of which may be applied the repair topcoat layers. The sealer is expected to provide this smoothness with essentially no sanding, and the sealer is conventionally applied in one coat at a dry film thickness around 25 microns. The sealer may be applied over a previously applied primer to hide the sand scratch marks produced when sanding the primer. Oftentimes, in the absence of a sealer, these sanding marks may be transmitted through to the basecoat and are visible as an optical defect in the repair part. A sealer may also be applied to a partial sand-through repair spot to negate the often variable surface energies created by the multiple exposed surfaces. These variable surface energies sometimes lead to optical defects visible in the basecoat layer (known as "ringing"). In this case, the sealer provides a consistent surface energy layer across the surface, on top of which the topcoat is applied. Because the sealer is applied prior to the repair topcoat and is generally not sanded, the "feather-out" area towards the edge of the repair where the contiguous sealer film blends into the original, unsanded area should be smooth enough to be topcoated without additional processing. It is further desirable for the sealer to dry and be processable within 10 to 15 minutes after application.

0028A multilayer coated substrate is provided comprising: <ol id="ol0001" compact="compact"><li>A) a substrate;</li><li>B) a primer composition applied directly to a surface of the substrate, forming a first coating;</li><li>C) a sealer composition applied on top of the first coating; and</li><li>D) at least one topcoat applied on top of the sealer composition, wherein the topcoat is a colored monocoat or a composite coating system comprising a colored basecoat followed by a clear coat;</li></ol> wherein the sealer composition and the primer composition comprises a waterborne curable film-forming composition, the waterborne curable film-forming composition for the primer composition comprising: <ol id="ol0002" compact="compact"><li>a) a first component comprising an aqueous dispersion of a pigment and <ol id="ol0003" compact="compact"><li>i) polymeric urethane-shell particles having a core-shell morphology and having hydroxyl functional groups, wherein the core of the polymeric urethane-shell particles is prepared from a monomer mixture comprising hydrophobic, ethylenically unsaturated monomers and wherein the shell of the polymeric urethane-shell particles comprises a polyurethane or polyurethane-urea polymer;</li></ol></li><li>b) a second component comprising a polyisocyanate crosslinking agent; and optionally</li><li>c) a hydroxyl functional, water dispersible acrylic polymer, wherein the primer composition is applied in no more than two coats and demonstrates a dry film thickness of 50 to 150 microns, the particles used in the composition have an average particle size of 10 to 300 nm, wherein the average particle size is the Z average mean value,</li></ol> the waterborne curable film-forming composition for the sealer composition comprising: <ol id="ol0004" compact="compact"><li>a) a first component comprising an aqueous dispersion of a pigment and <ol id="ol0005" compact="compact"><li>i) polymeric urethane-shell particles having a core-shell morphology and having hydroxyl functional groups, wherein the core of the polymeric urethane-shell particles is prepared from a monomer mixture comprising hydrophobic, ethylenically unsaturated monomers and wherein the shell of the polymeric urethane-shell particles comprises a polyurethane or polyurethane-urea polymer; or</li><li>ii) polymeric acrylic-shell particles having a core-shell morphology and having hydroxyl functional groups, wherein the core of the polymeric acrylic-shell particles is prepared from a monomer mixture comprising hydrophobic, ethylenically unsaturated monomers and wherein the shell of the polymeric acrylic-shell particles is prepared from a monomer mixture comprising hydrophilic, ethylenically unsaturated monomers;</li></ol></li><li>b) a second component comprising a polyisocyanate crosslinking agent; and optionally</li><li>c) a hydroxyl functional, water dispersible acrylic polymer, wherein the sealer composition is applied in no more than two coats and demonstrates a dry film thickness of 20 to 50 microns, the particles used in the composition have an average particle size of 10 to 300 nm, wherein the average particle size is the Z average mean value.</li></ol>

0029Suitable pigments for use in the aqueous dispersion of the first component a) include any organic and/or inorganic pigments typically used in primer or sealer compositions. Example pigments and/or pigment compositions include, but are not limited to, carbazole dioxazine crude pigment, azo, monoazo, disazo, naphthol AS, salt type (lakes), benzimidazolone, condensation, metal complex, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylcarbonium, quinophthalone pigments, diketo pyrrolo pyrrole red ("DPPBO red"), titanium dioxide, carbon black and mixtures thereof. The terms "pigment" and "colored filler" can be used interchangeably.

0030The polymeric particles used in the first component a) of the waterborne curable film-forming composition may comprise i) polymeric urethane-shell particles having a core-shell morphology and having hydroxyl functional groups, wherein the core of the polymeric urethane-shell particles is prepared from a monomer mixture comprising hydrophobic, ethylenically unsaturated monomers and wherein the shell of the polymeric urethane-shell particles comprises a polyurethane or polyurethane-urea polymer.

0031The core (interior domain) and shell (surface domain) polymers may be covalently attached to each other, and the polymeric particles are typically formed by emulsion polymerization in an aqueous medium. Exemplary polymerization methods are demonstrated in the examples below. The core typically constitutes 30 to 70 percent by weight of the polymeric particle, while the shell usually makes up 70-30 percent by weight of the polymeric particle. Often the weight ratio of the core to the shell is greater than 1:1. Also, the core may be internally crosslinked through the use of monomers having multiple ethylenically unsaturated groups, such as ethylene glycol dimethacrylate. These internally crosslinking monomers are typically used in amounts up to 10 percent by weight, such as 3-10 percent by weight, based on the total weight of resin solids in the particles. The shell polymer is designed to be more polar than the core by including functional groups such as hydroxyl and acid groups. The shell polymer is typically formed from polyisocyanates and polyols, including acid functional polyols, in an amount sufficient to allow for dispersion of the polymeric particles in an aqueous medium.

0032Ethylenically unsaturated monomers used to prepare the core of the polymeric urethane-shell particles may include hydrophobic monomers such as n-butyl (meth)acrylate, isobutyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, and t-butyl (meth) acrylate, usually together with one or more other polymerizable ethylenically unsaturated monomers, including monomers having multiple ethylenically unsaturated groups such as ethylene glycol dimethacrylate and hexanediol diacrylate. By "hydrophobic" is meant that the monomers have non-polar properties and have a tendency to interact with, be miscible with, or be dissolved by non-polar solvents such as alkanes and oils. By definition, a molecule may be non-polar either when there is an equal sharing of electrons between the two atoms of a diatomic molecule or because of the symmetrical arrangement of polar bonds in a more complex molecule, such that there is no overall dipole in the molecule.

0033Other useful alkyl esters of acrylic acid or methacrylic acid include aliphatic alkyl esters containing from 1 to 30, and usually 4 to 18 carbon atoms in the alkyl group. Non-limiting examples include methyl (meth)acrylate, ethyl (meth)acrylate, and n-butyl (meth)acrylate. Suitable other copolymerizable ethylenically unsaturated monomers include vinyl aromatic compounds such as styrene and vinyl toluene. Hydroxyl functional ethylenically unsaturated monomers such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate may also be used in amounts that do not significantly adversely affect the hydrophobicity of the core.

0034The polymeric urethane-shell particles often contain primary hydroxyl functional groups. Usually, more than 50 percent of the hydroxyl functional groups in the particles are primary; often more than 75 percent, and more often more than 90 percent. It is also possible that 100 percent of the hydroxyl functional groups in the particles may be primary. An exemplary monomer mixture used to prepare the core of the polymeric particles comprises at least one of n-butyl (meth)acrylate, isobutyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, and styrene, and optionally at least one of hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate.

0035The shell of the polymeric urethane-shell particles comprises a polyurethane or polyurethane-urea polymer containing acid functional groups. Polyurethane polymers are prepared by reacting polyols with a polyisocyanate; often the OH/NCO equivalent ratio is less than 1:1 so that free isocyanate groups are present in the intermediate isocyanate prepolymer. Suitable polyols include ethylene glycol, propylene glycol, butylene glycol, 1,6-hexylene glycol, neopentyl glycol, diethylene glycol, glycerol, trimethylol propane, and pentaerythritol. Polyols having dual functionality such as dimethylol propionic acid are also suitable, to incorporate acid functional groups into the resulting polyurethane. Polymeric polyols such as acrylic and polyester polyols may also be used. Such polymeric polyols may additionally have acid functional groups. The organic polyisocyanate which is used to prepare the polyurethane can be an aliphatic or an aromatic polyisocyanate or a mixture of the two. Diisocyanates are most often used, although higher polyisocyanates can be used in place of or in combination with diisocyanates. Examples of suitable aromatic diisocyanates are 4,4'-diphenylmethane diisocyanate and toluene diisocyanate. Examples of suitable aliphatic diisocyanates are straight chain aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate. Also, cycloaliphatic diisocyanates can be employed. Examples include isophorone diisocyanate and 4,4'-methylene-bis-(cyclohexyl isocyanate). Examples of suitable higher polyisocyanates are 1,2,4-benzene triisocyanate and polymethylene polyphenyl isocyanate. The free isocyanate end groups are then reacted with polyols, such as trimethylol propane and pentaerythritol to produce a urethane shell with a plurality of curable chain-end hydroxyl groups. This molecular architecture is particularly advantageous for ambient cure applications.

0036As noted above, the polyurethanes can be prepared with unreacted carboxylic acid groups, which upon neutralization with bases such as amines allows for dispersion into aqueous medium. Neutralization of acid groups on the polymer may be done using, for example, inorganic bases such as ammonium hydroxide or amines such as dimethylethanolamine, diisopropanolamine, triethylamine, and the like. Effective dispersion techniques may include high shear mixing such as by homogenization, emulsification by use of an emulsifier, use of rotor / stator mixers, Cowles dispersers, or mixing a small volume of material with a conventional stirrer at a high agitation rate.

0037Where the shell of the polymeric particles comprises a polyurethane-urea polymer, a polyurethane polymer may be prepared using reactants described above, but with an OH/NCO equivalent ratio less than 1:1 so that free isocyanate groups are present in the product. During production of the particles in the aqueous medium, the free isocyanate groups on the polyurethane polymer shell may be reacted with (poly)amines present in the aqueous medium to form urea linkages on the particles.

0038A "polyamine" is an amine with at least two amino groups. For example, the polyamine may be a diamine, and the amine nitrogens on the diamine are equally reactive; that is, all of the amine nitrogens are equally likely to react with another functional group. Alternatively, the amine nitrogens of the diamine may be unequal in reactivity due to steric hindrance. Examples of suitable diamines include ethylene diamine, 1,2-diaminopropane, 1,5-diamino-2-methylpentane, 1,3- diaminopentane, 1,2-diaminocyclohexane, 1,6-diaminohexane, 1,11-diaminoundecane, 1,12-diaminododecane, 3-(cyclohexylamino)propylamine, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane, (isophorone diamine ("IPDA")), 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexyl methane, 3,3'-[1,4-butanediylbis-(oxy)bis]-1-propanamine, methanediamine, and diamino functional polyether polyamines having aliphatically bound primary amino groups, examples of which include JEFFAMINE D-230, JEFFAMINE D-400, JEFFAMINE D-2000, and JEFFAMINE D-4000, available from Huntsman Corporation.

0039Suitable higher polyamines include primary and secondary triamines and/or tetraamines. Examples of suitable triamines include but are not limited to diethylene triamine, dipropylene triamine, bis(hexamethylene) triamine and triamino functional polyetherpolyamines having aliphatically bound primary amino groups (examples include JEFFAMINE T-403, T-3000, T-5000, available from Huntsman Corporation). For example, the amine can be an amine terminated (that is, an amine on each end, thus rendering the amine difunctional) polyethylene or polypropylene glycol, such as a polypropylene having an average molecular weight of 4000 or a polyethylene having an average molecular weight of 600. One skilled in the art will understand that these types of products are sold with a mixture of polymers having a relatively wide range of molecular weight, such as 4000+/- 500 or 600+/- 200 but that the average molecular weight is 4000 or 600. Monoamines may also be used to react with the isocyanate to generate urea linkages. Suitable monoamines include ethanolamine and diethanolamine.

0040The polymeric particles used in the first component a) of the waterborne curable film-forming composition may comprise ii) polymeric acrylic-shell particles having a core-shell morphology and having hydroxyl functional groups, wherein the core of the polymeric acrylic-shell particles is prepared from a monomer mixture comprising hydrophobic, ethylenically unsaturated monomers and wherein the shell of the polymeric acrylic-shell particles is prepared from a monomer mixture comprising hydrophilic, ethylenically unsaturated monomers.

0041The core of the polymeric acrylic-shell particles may be prepared similarly to that of the polymeric urethane-shell particles, using similar monomers and techniques. The shell of the polymeric acrylic-shell particles is prepared from a monomer mixture comprising hydrophilic, ethylenically unsaturated monomers, or monomers that may be rendered hydrophilic. By "hydrophilic" is meant, as is understood in the art, that the monomers or repeat units in the resulting polymer have a tendency to interact with, be miscible with, or be dissolved by water and/or other polar substances. The monomers themselves may be polar. By definition, a polar molecule has a net dipole as a result of the opposing charges (i.e. having partial positive and partial negative charges) from polar bonds arranged asymmetrically within its structure. When acid functional monomers are used, the hydrophilic monomers may be selected so as to provide the resulting polymer with an acid value of at least 45 mg KOH / g resin, such as at least 60 mg KOH / g resin, or at least 125 mg KOH / g resin, based on the total weight of resin solids of the polymer. Suitable hydrophilic monomers include one or more of methoxypolyethylene glycol (meth)acrylate, (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid and fumaric acid. Hydroxyl functional ethylenically unsaturated monomers may be used, such as hydroxyalkyl acrylates and methacrylates; i. e., hydroxyalkyl (meth)acrylates, typically having 2 to 4 carbon atoms in the hydroxyalkyl group, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxy functional adducts of caprolactone, as well as other beta-hydroxy ester functional monomers. Methyl (meth)acrylate, (meth)acrylonitrile, dimethylaminoethyl(meth)acrylate, and hydrophilic (meth)acrylamides such as isopropyl (meth)acrylamide are also suitable hydrophilic monomers.

0042Other suitable hydrophilic monomers include amine functional ethylenically unsaturated monomers such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and the like. Protonated (cationic) derivatives of these monomers may also be used. As noted above, monomers containing groups that may be rendered hydrophilic after polymerization may also be used to form the shell of the particle. For example, epoxy functional ethylenically unsaturated monomers such as glycidyl methacrylate and the like may be used to form the polymer, and then epoxy functional groups on the resulting polymer may be post-reacted with a compound such as an amino alcohol using known methods to render the polymer more hydrophilic.

0043In an exemplary particle, the polymeric acrylic-shell particles have primary hydroxyl functional groups; the core of the polymeric acrylic-shell particles is prepared from a monomer mixture comprising at least one of n-butyl (meth)acrylate, isobutyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, and styrene and optionally at least one of hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; and the shell of the polymeric acrylic-shell particles is prepared from a monomer mixture comprising at least one of methoxypolyethylene glycol (meth)acrylate, (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxy functional adducts of caprolactone, methyl (meth)acrylate, (meth)acrylonitrile, dimethylaminoethyl(meth)acrylate, isopropyl (meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and ethylene glycol dimethacrylate. These particles are particularly useful in sealer compositions.

0044The polymeric particles i) and ii) have a core/shell structure as noted above. Though not intending to be bound by any theory, it is believed that the core-shell structures of the particles contribute to higher film builds attainable with the waterborne curable film-forming compositions used as primers and/or sealers in the multilayer coated substrates of the present invention, compared to those of conventional primer and sealer compositions.

0045The particles used in the compositions of the present invention have an average particle size of 10 to 300 nm, such that they would be considered nanoparticles, wherein the average particle size is the Z average mean value. Particle size may be determined from among the numerous techniques known in the art, such as the method described below. The particle size is measured with a Malvern Zetasizer, which is a high performance two angle particle size analyzer for the enhanced detection of aggregates and measurement of small or dilute samples, and samples at very low or high concentration using dynamic light scattering. Typical applications of dynamic light scattering are the characterization of particles, emulsions or molecules, which have been dispersed or dissolved in a liquid. The Brownian motion of particles or molecules in suspension causes laser light to be scattered at different intensities. Analysis of these intensity fluctuations yields the velocity of the Brownian motion and hence the particle size using the Stokes-Einstein relationship. The reported particle sizes for all examples are the Z average mean value.

0046The first component a) is present in the waterborne curable film-forming composition in amounts of at least 25 percent by weight, such as at least 40 percent by weight or at least 50 percent by weight, and in amounts of at most 95 percent by weight, such as at most 90 percent by weight or at most 85 percent by weight, based on the total weight of resin solids in the curable film-forming composition.

0047The second component b) in the waterborne curable film-forming composition comprises a polyisocyanate crosslinking agent. As used herein, the term "polyisocyanate" is intended to include blocked (or capped) polyisocyanates as well as unblocked polyisocyanates. The polyisocyanate can be aliphatic, aromatic, or a mixture thereof. Although higher polyisocyanates such as isocyanurates of diisocyanates are often used, diisocyanates can also be used. Mixtures of polyisocyanate crosslinking agents can be used.

0048Polyisocyanates that may be utilized as crosslinking agents can be prepared from a variety of isocyanate-containing materials. Examples of suitable polyisocyanates include the following diisocyanates and trimers prepared therefrom: toluene diisocyanate, 4,4'-methylene-bis(cyclohexyl isocyanate), isophorone diisocyanate, an isomeric mixture of 2,2,4- and 2,4,4-trimethyl hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, tetramethyl xylylene diisocyanate and 4,4'-diphenylmethylene diisocyanate. Isocyanate prepolymers, for example reaction products of polyisocyanates with polyols also can be used. The polyisocyanate crosslinking agent is usually water emulsifiable or dispersible for use in the waterborne curable film-forming compositions of the present invention.

0049If the polyisocyanate is to be blocked or capped, any suitable aliphatic, cycloaliphatic, or aromatic alkyl monoalcohol or phenolic compound known to those skilled in the art can be used as a capping agent for the polyisocyanate. Examples of suitable blocking agents include those materials which would unblock at elevated temperatures such as lower aliphatic alcohols including methanol, ethanol, and n-butanol; cycloaliphatic alcohols such as cyclohexanol; aromatic-alkyl alcohols such as phenyl carbinol and methylphenyl carbinol; and phenolic compounds such as phenol itself and substituted phenols wherein the substituents do not affect coating operations, such as cresol and nitrophenol. Glycol ethers may also be used as capping agents. Suitable glycol ethers include ethylene glycol butyl ether, diethylene glycol butyl ether, ethylene glycol methyl ether and propylene glycol methyl ether. Other suitable capping agents include oximes such as methyl ethyl ketoxime, acetone oxime and cyclohexanone oxime, lactams such as epsilon-caprolactam, pyrazoles such as dimethyl pyrazole, and amines such as dibutyl amine.

0050The amount of the crosslinking agent in the curable film-forming composition generally ranges from 5 to 75 percent by weight based on the total weight of resin solids in the curable film-forming composition. For example, the minimum amount of crosslinking agent may be at least 5 percent by weight, often at least 10 percent by weight and more often, at least 15 percent by weight. The maximum amount of crosslinking agent may be 75 percent by weight, more often 60 percent by weight, or 50 percent by weight. Ranges of crosslinking agent may include, for example, 5 to 50 percent by weight, 5 to 60 percent by weight, 10 to 50 percent by weight, 10 to 60 percent by weight, 10 to 75 percent by weight, 15 to 50 percent by weight, 15 to 60 percent by weight, and 15 to 75 percent by weight.

0051The waterborne curable film-forming composition may further comprise c) a hydroxyl functional, water dispersible acrylic polymer. Suitable acrylic compounds include copolymers of one or more alkyl esters of acrylic acid or methacrylic acid, optionally together with one or more other polymerizable ethylenically unsaturated monomers. Useful alkyl esters of acrylic acid or methacrylic acid include aliphatic alkyl esters containing from 1 to 30, and often 4 to 18 carbon atoms in the alkyl group. Non-limiting examples include methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethyl acrylate, butyl acrylate, and 2-ethyl hexyl acrylate. Suitable other copolymerizable ethylenically unsaturated monomers include vinyl aromatic compounds such as styrene and vinyl toluene; nitriles such as acrylonitrile and methacrylonitrile; vinyl and vinylidene halides such as vinyl chloride and vinylidene fluoride and vinyl esters such as vinyl acetate.

0052The water dispersible acrylic polymer c) can include hydroxyl functional groups, which are often incorporated into the polymer by including one or more hydroxyl functional monomers in the reactants used to produce the copolymer. The ratio of primary to secondary hydroxyl functional groups in the acrylic copolymer is usually at least 2.5:1. Useful hydroxyl functional monomers include hydroxyalkyl acrylates and methacrylates, typically having 2 to 4 carbon atoms in the hydroxyalkyl group, such as hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, hydroxy functional adducts of caprolactone and hydroxyalkyl acrylates, and corresponding methacrylates, as well as the beta-hydroxy ester functional monomers described below. The acrylic polymer can also be prepared with N-(alkoxymethyl)acrylamides and N-(alkoxymethyl)methacrylamides.

0053Beta-hydroxy ester functional monomers can be prepared from ethylenically unsaturated, epoxy functional monomers and carboxylic acids having from about 13 to about 20 carbon atoms, or from ethylenically unsaturated acid functional monomers and epoxy compounds containing at least 5 carbon atoms which are not polymerizable with the ethylenically unsaturated acid functional monomer.

0054Useful ethylenically unsaturated, epoxy functional monomers used to prepare the beta-hydroxy ester functional monomers include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether, 1:1 (molar) adducts of ethylenically unsaturated monoisocyanates with hydroxy functional monoepoxides such as glycidol, and glycidyl esters of polymerizable polycarboxylic acids such as maleic acid. (Note: these epoxy functional monomers may also be used to prepare epoxy functional acrylic polymers.) Examples of carboxylic acids include saturated monocarboxylic acids such as isostearic acid and aromatic unsaturated carboxylic acids.

0055Useful ethylenically unsaturated acid functional monomers used to prepare the beta-hydroxy ester functional monomers include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid; dicarboxylic acids such as itaconic acid, maleic acid and fumaric acid; and monoesters of dicarboxylic acids such as monobutyl maleate and monobutyl itaconate. The ethylenically unsaturated acid functional monomer and epoxy compound are typically reacted in a 1:1 equivalent ratio. The epoxy compound does not contain ethylenic unsaturation that would participate in free radical-initiated polymerization with the unsaturated acid functional monomer. Useful epoxy compounds include 1,2-pentene oxide, styrene oxide and glycidyl esters or ethers, often containing from 8 to 30 carbon atoms, such as butyl glycidyl ether, octyl glycidyl ether, phenyl glycidyl ether and para-(tertiary butyl) phenyl glycidyl ether. Particular glycidyl esters include those of the structure: <chemistry id="chem0001" num="0001"><img file="EP3377550B2_D0001.tif" /></chemistry> where R is a hydrocarbon radical containing from about 4 to about 26 carbon atoms. Typically, R is a branched hydrocarbon group having from about 8 to about 10 carbon atoms, such as neopentanoate, neoheptanoate or neodecanoate. Suitable glycidyl esters of carboxylic acids include VERSATIC ACID 11 and CARDURA E, each of which is commercially available from Shell Chemical Co.

0056Acrylic polymers can be prepared via aqueous emulsion polymerization techniques and used directly in the preparation of aqueous coating compositions. More often, the acrylic polymers are prepared via organic solution polymerization with groups capable of salt formation such as acid or amine groups, and upon neutralization of these groups with a base or acid, the polymers can be dispersed into aqueous medium. Generally any method of producing such polymers that is known to those skilled in the art utilizing art recognized amounts of monomers can be used. The acrylic polymer typically has a calculated glass transition temperature (T_g) of greater than 10 °C, often around 29 °C.

0057The water dispersible acrylic polymer c) is often added to the waterborne curable film-forming composition in the form of an aqueous emulsion of the acrylic polymer, and the acrylic polymer is typically prepared from a reaction mixture comprising butyl acrylate, methyl methacrylate, styrene, hydroxyethyl methacrylate, acrylic acid, and a reaction product of acrylic acid and a glycidyl ester.

0058When used, the water dispersible acrylic polymer c) is usually present in the first component of the waterborne curable film-forming composition in an amount of up to 30 percent by weight, based on the total weight of resin solids in the first component of the curable film-forming composition. The water dispersible acrylic polymer may be used as a grind vehicle for the pigment in the first component. At least a portion (less than 100 percent) of the aqueous emulsion of the acrylic polymer may be used as a grind vehicle, or up to 100 percent (i. e., up to its entirety).

0059The waterborne curable film-forming compositions used in the present invention may contain adjunct ingredients conventionally used in coating compositions. Optional ingredients such as, for example, plasticizers, surfactants, thixotropic agents, anti-gassing agents, organic cosolvents, flow controllers, anti-oxidants, UV light absorbers and similar additives conventional in the art may be included in the composition. These ingredients are typically present at up to about 40% by weight based on the total weight of resin solids.

0060The waterborne curable film-forming compositions of the present invention usually have a total solids content of at least 50 percent by weight, and a VOC up to 2.1.

0061It is often not practical to store ambient-cure coatings as a one-package composition, but rather they must be stored as multi-package coatings to prevent the components from curing prior to use. The term "multi-package coatings" refers to coatings in which various components are maintained separately until just prior to application. The compositions of the present invention are usually multi-package coatings, such as a two-package coating, wherein the first component a) is a first package and the second component b) is the second package. When the hydroxyl functional, water dispersible acrylic polymer c) is present, it may be a separate, third package and/or combined with either or both of the other two packages. Usually it is present at least in the first package since it is often used as a grind vehicle for the pigment in the first component.

0062In the multilayer coated substrates of the present invention comprising both a primer and a sealer composition, both comprise any of the waterborne curable film-forming compositions described above. They may be the same as each other or different.

0063After application of the sealer composition, light sanding of the sealer may be performed, though it is often not necessary, and at least one additional coating composition may be applied. Usually this comprises one or more topcoats. A topcoat provides, <i>inter alia</i>, aesthetic properties such as color to the substrate, and may be a monocoat or a composite coating system comprising a colored basecoat followed by a clear coat. The multilayer coated substrates of the present invention, prepared using the waterborne primer and/or sealer compositions of the present invention, demonstrate minimal to no film defects in the form of pops and/or pinholes.

0064Each coating composition (primer, sealer, etc.) may be applied by known application techniques, such as dipping or immersion, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or by roll-coating. Usual spray techniques and equipment for air spraying and electrostatic spraying, either manual or automatic methods, can be used.

0065After application of a composition, a film is formed by driving solvent, i.e., organic solvent and water, out of the film by heating or by an air-drying period. Suitable drying conditions will depend on the particular composition and/or application, but in some instances a drying time of from about 5 to 30 minutes at a temperature of about room temperature to 60°C will be sufficient. More than one coating layer of each composition may be applied if desired. Usually between coats, the previously applied coat is flashed; that is, exposed to ambient conditions for the desired amount of time.

0066The primer composition of the present invention is applied in no more than two coats and yet demonstrates a dry film thickness of at least 50 microns or at least 60 microns, or at least 100 microns, to at most 150 microns or at most 125 microns. This is not usually possible with waterborne primer compositions, which typically require three or more coats to achieve a comparable film build, resulting in film defects such as pops and/or pinholes. Dry film thicknesses may be measured 24 hours after application of the coating when cured at ambient temperatures, using a DUALSCOPE FMP40C with an FD13H probe, available from Fischer Technologies, Inc., according to manufacturer's directions.

0067The primer composition of the present invention is typically curable at a temperature below 60°C, often below 30°C. It is also sandable within fifteen minutes of application. The primer composition of the present invention may be cured overnight at ambient temperatures or force cured for 30 minutes at 60 °C.

0068The sealer composition is applied on top of the primer composition, usually after the primer has been sanded. The sealer composition of the present invention is applied in no more than two coats and yet demonstrates a dry film thickness of 20 to 50 microns. The sealer composition of the present invention is typically curable at a temperature below 60°C, often below 30°C. Light sanding, or de-nibbing, of surface imperfections is possible within fifteen minutes of drying.

0069The following examples are intended to illustrate variations of the invention, and should not be construed as limiting the invention in any way. Unless otherwise indicated, all parts are by weight. The sealer and primer compositions of the following examples can be used in the multilayer coated substrate according to the claims.

<u>EXAMPLES</u>

<u>Example A</u>

0070A polyesterdiol for use in the preparation of a urethane dispersion was prepared as follows: To a 4-necked round bottom flask fitted with a stirrer, gas inlet, packed column, thermometer, and condenser was added 2478g 1,6-hexanediol, 1456g neopentyl glycol, 1533g adipic acid, 2324g isophthalic acid, 343g maleic anhydride, 7.2g butylstannoic acid and 7.2g triphenyl phosphite. The reaction mixture was heated in stages under an inert N₂ atmosphere to a maximum temperature of 230°C while ensuring that the head temperature did not exceed 100°C. When the acid value reached 10, a Dean Stark trap was fitted to the flask and 100g toluene was added to facilitate removal of the final amounts of water. The reaction was held until the residual acid value was &lt; 2, after which time the reaction was cooled to 180°C and vacuum was applied for 30 minutes. The resulting viscous resin had a solids of 99%, a viscosity at 80% solids in butyl glycol of Z1 (Gardner-Holdt), and a theoretical OH value of 110.

<u>Example B</u>

0071A urethane dispersion for use in the preparation of urethane-shell particles was prepared as follows: To a 4-necked round bottom flask fitted with a stirrer, gas inlet tube, addition funnel, thermometer and condenser was added 120.6g dimethylolpropionic acid, 616.2g of the polyesterdiol of Example A, 1.5g triphenylphosphite, 1.9g ionol, 1.5g dibulyltin dilaurate. The mixture was heated to 80°C for 30 minutes to dissolve the dimethylolpropionic acid. 613.5 butyl methacrylate was then added and the mixture was cooled to 50°C and maintained under an air atmosphere. 466.2g isophorone diisocyanate was then added via addition funnel over 20 minutes while ensuring the temperature did not exceed 70°C. The addition funnel was then rinsed with 30g butyl methacrylate, and the mixture was heated to 100°C. The reaction was held for 2-3 hours at 100°C, until the NCO value stalled. 160.8g trimethylol propane and 81.6g pentaerythritol were then added, and the reaction was held for 1 hour. After this time, infrared analysis showed complete consumption of isocyanate. The solution was cooled to 90°C, 145g butylglycol and 48.1g dimethyl ethanolamine were added, and stirred for 10 minutes. 1923g of the above solution was then dispersed into 2176g deionized water that was preheated to 30°C in a 4-necked round bottom flask under air atmosphere. The ensuing small particle size, waterborne dispersion had a solids level of 31.5%, a viscosity of 228 cps, a pH value of 6.7, and a particle size of ∼ 50 nm.

<u>Example C</u>

0072A dispersion of urethane-shell particles was prepared as follows To a 4-necked round bottom flask fitted with a stirrer, gas inlet for N₂ sparge, thermometer and condenser was added 2750 g of the urethane dispersion of Example B, 410g deionized water, 74.3g 2-ethylhexyl acrylate, 11g butyl methacrylate, 222.8g styrene, and 165g hydroxyethyl methacrylate. The solution was heated to 35°C and sparged with N₂ for 30 minutes to remove dissolved oxygen. A solution of 0.0033g ferrous ammonium sulfate in 25g deionized water was then added followed by the addition of a solution of 3.18g isoascorbic acid, 3.21g dimethyl ethanolamine in 75g of deionized water. The solution was stirred for 5 minutes and -80% of a solution of 14.5g of a 35% hydrogen peroxide solution diluted in 120g of deionized water added over ∼ 5 minutes. A rapid exotherm with a maximum temperature of 68°C ensued. The reaction was then held at 65°C for 30 min, then cooled to 30°C. The remainder of the hydrogen peroxide solution was then added over 2-3 minutes. A solution of 17.8g dimethyl ethanolamine in 35g of deionized water was added. The nearly transparent dispersion had a solids content of 43%, a viscosity of 290 cps, a pH value of 7.5 and a particle size of ∼ 60 nm.

<u>Example D</u>

0073A dispersion of urethane-shell particles was prepared as follows: To a 4-necked round bottom flask fitted with a stirrer, gas inlet for N₂ sparge, thermometer and condenser was added 500g of the urethane dispersion of Example B, 95g deionized water, 22.5g butyl acrylate, 7.5g butyl methacrylate, 56.2g styrene, and 75g hydroxypropyl methacrylate. A solution of 0.7g mercaptopropionic acid, 0.6g of dimethyl ethanolamine in 20g of deionized water was then added. The solution was heated to 35°C and sparged with N₂ for 30 minutes to remove dissolved oxygen. A solution of 0.43g LUPEROX TBH70x (t-butyl hydroperoxide) in 15g deionized water was then added. A solution of 0.0069g ferrous ammonium sulfate, 0.43g sodium metabisulfite and 0.21g dimethyl ethanolamine in 50g deionized water was then added over ∼ 5 minutes to initiate the polymerization. A rapid exotherm with a maximum temperature of 70°C ensued. The reaction was then held at 65°C for 30 min, then cooled to 30°C. A solution of 2.5g dimethyl ethanolamine in 5g of deionized water was added. The nearly transparent dispersion had a solids content of 44%, a viscosity of 224 cps, a pH value of 8.2.

<u>Example E</u>

0074An acrylic dispersion for use as the component c) in the waterborne curable film-forming composition was prepared as follows: To a 4-necked round bottom flask fitted with a stirrer, gas inlet for N₂ sparge, thermometer and condenser was added 289g Cardura E and 190g DOWANOL PM and the mixture was heated to reflux (∼ 135°C). To one addition funnel was added 80g t-Butyl peracetate (LUPEROX 7M50) and 40g DOWANOL PM, to a second addition funnel was added 238g butyl acrylate, 190.4g methyl methacrylate, 428.4g styrene, 375.7g hydroxyethyl methacrylate, and 86.7g acrylic acid. The initiator solution is added over a total of 4 hours, the monomer addition is added over a total of 3 hours (not including stoppages - see below). Both the initiator and monomer additions are begun. After 40 minutes the monomer addition is stopped, an additional 30.6g of acrylic acid and 5g DOWANOL PM are added and the mixture is stirred for 10 min. The monomer addition in re-started (50min). After another 30 minutes (80 total) the monomer addition is stopped and 30.6g acrylic acid and 5g DOWANOL PM are added and the mixture is stirred for 10 min. The monomer addition is re-started (90min). After another 40 min the monomer addition is stopped and 30.6g acrylic acid and 5g DOWANOL PM are added and the mixture is stirred for 10 min. The monomer addition is re-started (140min), and the monomer addition is complete after 40 minutes. After both additions are complete, the reaction is held for 1.5 hours. The resin is then cooled to 90°C, followed by the addition of 90.8g DMEA. A fine particle size dispersion is produced by then dispersing 1845g of the acrylic into 2185g of deionized water that has been preheated to 70°C. The final dispersion had a solids content of 40%, a viscosity of 700 cps, a pH value of 7.5 and a particle size of ∼ 90 nm.

<u>Example F</u>

0075A hyperbranched acrylic polymer for use in the preparation of acrylic-shell particles was prepared as follows: A 300 cm³ electrically heated continuous stirred tank reactor with an internal cooling coil was filled with butyl glycol and the temperature was adjusted to 210°C. The following charge was fed to the reactor at the rate of 100 ml/ min - 1600g methyl methacrylate, 1460g butyl acrylate, 400g hydroxyethyl methacrylate, 400g acrylic acid and 140g allyl methacrylate, 320g butyl glycol, and 160g ditertiary butyl peroxide at the rate of 100 ml/min. The residence time in the reactor was ∼3 minutes. The reactor was kept volumetrically full at a pressure of 400-600 psi, and the temperature was held constant at ∼ 210°C. The reactor output was drained to a 3000 cm³ continuous stirred tank reactor fitted with a pressure relief valve and set to 170°C. A chase initiator solution was then added to the contents of the tank reactor at the rate of 3 ml/min. The composition of this chase solution was 80g butyl gylcol and 40g di-tertiarybutyl peroxide. When ∼ 1500g of the product had been collected in the second reactor, the outlet valve as opened and the material was fed to a collection vessel at a rate that maintained a constant fill level resulting in 20 minute residence time. The resulting hyperbranched acrylic polymer had a solids content of 87.5%, an acid value of 65, a number average molecular weight of 1870 and a weight average molecular weight of 18000.

<u>Example G</u>

0076A dispersion of acrylic-shell particles were prepared as follows: To a 4-necked round bottom flask fitted with a stirrer, gas inlet for N2 sparge, thermometer and condenser was added 527g of Example F, 47g dimethyl ethanolamine, and 1914g deionized water that was pre-warmed to 50°C. The solution was held at 50°C and sparged with N2 for 30 minutes to remove dissolved oxygen. A solution of 3.46g ascorbic acid and 5.2g dimethyl ethanolamine in 20g deionized water was added, followed by a solution of 0.027g ferrous ammonium sulfate in 4g deionized water. In one addition funnel was added 6g t-butyl hydroperoxide (LUPEROX TBH70X) in 114g deionized water. In a separate addition funnel was added 316.8g butyl acrylate, 316.8g methyl methacrylate, 316.8g styrene, and 158.3g hydroxyethyl methacrylate. The initiator and monomer solution were then added simultaneously over 2.5 hours. After the additions were complete, the polymer was held for 1 hour at 50°C. A solution of 11.7g dimethyl ethanolamine in 10g deionized water was then added. The final dispersion had a solids content of 42.5%, a viscosity of 170 cps, a pH value of 7.8, and a particle size of 75 nm.

<b>Sealer</b>:

0077Urethane acrylate sealer coatings were prepared by first producing a grind paste (Examples H and I) made with the following ingredients. The binder portion of the grind paste may consist of either Urethane-shell particles of Example C or the Acrylic Dispersion of Example E. <tables id="tabl0001" num="0001"><table frame="all"><title><b>Table 1. Grind pastes for polyurethane acrylate sealer coating</b></title><tgroup cols="4" align="center"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="60mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><colspec colnum="4" colname="col4" colwidth="21mm" /><thead valign="middle"><row><entry /><entry /><entry>Example H</entry><entry>Example I</entry></row><row><entry>Charge</entry><entry>Name</entry><entry>Weight (g)</entry><entry>Weight (g)</entry></row></thead><tbody valign="middle"><row><entry>1(a)</entry><entry>Urethane-shell particles of Example C</entry><entry>833</entry><entry>---</entry></row><row><entry>1(b)</entry><entry>Acrylic dispersion of Example E</entry><entry>---</entry><entry>527</entry></row><row><entry>2</entry><entry>DISPERBYK 024¹</entry><entry>16</entry><entry>10</entry></row><row><entry>3</entry><entry>Dispex^® Ultra PA 4550²</entry><entry>21</entry><entry>13</entry></row><row><entry>4</entry><entry>SURFYNOL 104E³</entry><entry>25</entry><entry>16</entry></row><row><entry>5</entry><entry>Carbon Black</entry><entry>25</entry><entry>15</entry></row><row><entry>6</entry><entry>Titanium Dioxide</entry><entry>546</entry><entry>343</entry></row><row><entry>7</entry><entry>Barium Sulfate</entry><entry>614</entry><entry>390</entry></row><row><entry>8</entry><entry>Talc</entry><entry>437</entry><entry>277</entry></row><row><entry>9</entry><entry>Calcium Carbonate</entry><entry>240</entry><entry>152</entry></row><row><entry>10</entry><entry>DI Water</entry><entry>94</entry><entry>142</entry></row><row><entry>11</entry><entry>10 DMEA/90 DI Water</entry><entry>53</entry><entry>30</entry></row><row><entry>12</entry><entry>DI Water</entry><entry>287</entry><entry>121</entry></row><row rowsep="0"><entry namest="col1" nameend="col4" align="justify">¹Available from BYK</entry></row><row rowsep="0"><entry namest="col1" nameend="col4" align="justify">²Available from BASF</entry></row><row><entry namest="col1" nameend="col4" align="justify">³Available from Air Products</entry></row></tbody></tgroup></table></tables>

0078The ingredients of charges 1 through 10 were first dispersed with a high speed Cowles mixer for 30 minutes. Charge 11 was added and stirring continued for 30 minutes. Charge 12 was added and the mixture was basket milled on a Hockmeyer Micro Mill until a 7 Hegman was achieved. <tables id="tabl0002" num="0002"><table frame="all"><title><b>Table 2. Polyurethane Acrylate Sealer coating compositions</b></title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="60mm" align="center" /><colspec colnum="3" colname="col3" colwidth="21mm" align="center" /><colspec colnum="4" colname="col4" colwidth="22mm" align="center" /><thead valign="middle"><row><entry align="center" /><entry /><entry>Example J</entry><entry>Example K</entry></row><row><entry align="center">Charge</entry><entry>Name</entry><entry>Weight (g)</entry><entry>Weight (g)</entry></row></thead><tbody valign="middle"><row><entry align="center">1 (a)</entry><entry>Grind Paste of Example H</entry><entry>375</entry><entry>---</entry></row><row><entry align="center">1 (b)</entry><entry>Grind Paste of Example I</entry><entry>---</entry><entry>367</entry></row><row><entry align="center">2</entry><entry>Urethane-shell particles of Example C</entry><entry>254</entry><entry>244</entry></row><row><entry align="center">4</entry><entry>EHW8224 Hardener¹</entry><entry>97</entry><entry>103</entry></row><row><entry align="center">5</entry><entry>T494 Reducer2</entry><entry>73</entry><entry>88</entry></row><row rowsep="0"><entry namest="col1" nameend="col4" align="justify">¹Water reducible isocyanate available from PPG Industries</entry></row><row><entry namest="col1" nameend="col4" align="justify">²Waterbased reducer available from PPG Industries</entry></row></tbody></tgroup></table></tables>

0079Sealer coating compositions for use in the present invention were prepared as shown below:

0080The final paints had a solids content of 53% at application and ambient temperature viscosity of 20 seconds #4 DIN cup.

0081The sealer coating compositions of Example J and Example K were spray applied at ambient conditions. onto 24" x 34" x 0.04" aluminum door skin panels over a gray coil coating. The substrate panels were obtained from Q-Lab of Westlake, Ohio. The gray coil coating was first scuffed using a Scotch-Brite scouring sponge. The coating compositions were applied in one coat and then blown dry with a forced air knife. The dry film thickness was 25 - 33 microns. The control coating was a solvent borne Refinish sealer commercially available from PPG Industries, Inc. as ECS25. This was applied in one coat and was allowed to flash at ambient conditions from glossy to matte. The film thickness was about 25 - 28 microns. Film thicknesses of all coatings were measured using a DUALSCOPE FMP40C with an FD13H probe, available from Fischer Technologies, Inc., according to manufacturer's directions.

0082The sealer coatings were tested for their air drying capability through a body shop procedure called de-nibbing. De-nib on a sealer is done before application of the basecoat if there are dust or other very small particles (nibs) to be removed. It is a very light sanding by hand. De-nibbing on the sealers was performed with an 800 grit sand paper available from 3M at 10 minutes after the coatings were matte finish. The de-nib is considered a pass if the coating is not sticky, the sand paper does not drag, and a powder forms under the sand paper. Hardness of the sealer coatings can also be measured via a Konig pendulum hardness tester using ASTM D4366.

0083After about 30 minutes, the sealer coatings were topcoated. The first layer of topcoat was a basecoat available from PPG Industries, T409, applied to the door skin panels in two coats and force air dried after each coat. The total dry film thickness was 4 - 6 microns. A 2K Refinish clear coat commercially available from PPG Industries, Inc. as DC2000 was then applied over the coated panel in two coats with a flash between coats. The clear coated panels were allowed to flash overnight. The dry film thickness was approximately 50 microns.

0084The appearance of the coating stack was measured with a Byk - WAVESCAN and the results are reported as DOI / du / Wa / Wb / Wc / Wd. The Wa measurement is for short wavelength structure (0,01 - 0,3 mm). Wc for intermediate wavelengths (1-3 mm) and We for longer wavelength structures (10-30 mm). Smoothness is a particularly important property for an automotive coating and can depend on the relative roughness of all the layers in the coating stack. Lower du and W values and higher DOI values indicate a smoother film. <tables id="tabl0003" num="0003"><table frame="all"><title><b>Table 3. Denib Rating and Appearance Values</b></title><tgroup cols="8"><colspec colnum="1" colname="col1" colwidth="27mm" /><colspec colnum="2" colname="col2" colwidth="15mm" align="center" /><colspec colnum="3" colname="col3" colwidth="13mm" align="center" /><colspec colnum="4" colname="col4" colwidth="11mm" align="center" /><colspec colnum="5" colname="col5" colwidth="13mm" align="center" /><colspec colnum="6" colname="col6" colwidth="13mm" align="center" /><colspec colnum="7" colname="col7" colwidth="13mm" align="center" /><colspec colnum="8" colname="col8" colwidth="13mm" align="center" /><thead valign="middle"><row><entry /><entry>Denib</entry><entry>DOI</entry><entry>du</entry><entry>Wa</entry><entry>Wb</entry><entry>Wc</entry><entry>Wd</entry></row></thead><tbody valign="middle"><row><entry>Example J</entry><entry>Pass</entry><entry>87.9</entry><entry>6.4</entry><entry>25.2</entry><entry>39.5</entry><entry>28</entry><entry>35.2</entry></row><row><entry>Example K</entry><entry>Pass</entry><entry>88.9</entry><entry>6.8</entry><entry>25.1</entry><entry>35.6</entry><entry>24.2</entry><entry>26.8</entry></row><row><entry>Control ECS25</entry><entry>Pass</entry><entry>85</entry><entry>3.1</entry><entry>19.1</entry><entry>49.9</entry><entry>40.6</entry><entry>34.4</entry></row></tbody></tgroup></table></tables>

0085Acrylic sealer coatings were prepared by first producing a grind paste (Example L) made with the following ingredients. The binder portion of the grind paste may consist of the Acrylic Dispersion of Example E. <tables id="tabl0004" num="0004"><table frame="all"><title><b>Table 4. Grind Paste For Acrylic Sealer Coating</b></title><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="23mm" /><colspec colnum="2" colname="col2" colwidth="68mm" align="center" /><colspec colnum="3" colname="col3" colwidth="22mm" align="center" /><thead valign="middle"><row><entry align="center" /><entry /><entry>Example L</entry></row><row><entry align="center">Charge</entry><entry>Name</entry><entry>Weight (g)</entry></row></thead><tbody valign="middle"><row><entry align="center">1</entry><entry>Acrylic dispersion of Example E</entry><entry>490</entry></row><row><entry align="center">2</entry><entry>Disperbyk 024¹</entry><entry>9</entry></row><row><entry align="center">3</entry><entry>Dispex^® Ultra PA 4550²</entry><entry>12</entry></row><row><entry align="center">4</entry><entry>Surfynol 104E³</entry><entry>15</entry></row><row><entry align="center">5</entry><entry>Carbon Black</entry><entry>5</entry></row><row><entry align="center">6</entry><entry>Titanium Dioxide</entry><entry>321</entry></row><row><entry align="center">7</entry><entry>Barium Sulfate</entry><entry>361</entry></row><row><entry align="center">8</entry><entry>Talc</entry><entry>257</entry></row><row><entry align="center">9</entry><entry>Calcium Carbonate</entry><entry>141</entry></row><row><entry align="center">10</entry><entry>DI Water</entry><entry>131</entry></row><row><entry align="center">11 (a) 11(b)</entry><entry>10 DMEA/90 DI Water 5 DMEA/95 DI Water</entry><entry>-57</entry></row><row><entry align="center">12</entry><entry>DI Water</entry><entry>131</entry></row><row rowsep="0"><entry namest="col1" nameend="col3" align="justify">¹Available from BYK</entry></row><row rowsep="0"><entry namest="col1" nameend="col3" align="justify">²Available from BASF</entry></row><row><entry namest="col1" nameend="col3" align="justify">³Available from Air Products</entry></row></tbody></tgroup></table></tables>

0086The ingredients of charges 1 through 10 were first dispersed with a high speed Cowles mixer for 30 minutes. Charge 11(a) and/or 11(b) was added and stirring continued for 30 minutes. Charge 12 was added and the mixture was milled on a Hockmeyer Micro Mill until a 7 Hegman was achieved. <tables id="tabl0005" num="0005"><table frame="all"><title><b>Table 5. Acrylic Sealer Coating Composition</b></title><tgroup cols="3" align="center"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="56mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><thead valign="middle"><row><entry /><entry /><entry>Example M</entry></row><row><entry>Charge</entry><entry>Name</entry><entry>Weight (g)</entry></row></thead><tbody valign="middle"><row><entry>1</entry><entry>Grind Paste of Example L</entry><entry>63</entry></row><row><entry>2</entry><entry>Acrylic-shell particles of Example G</entry><entry>47</entry></row><row><entry>3</entry><entry>EHW8224 Hardener¹</entry><entry>13</entry></row><row><entry>4</entry><entry>T494 Reducer²</entry><entry>8</entry></row><row rowsep="0"><entry namest="col1" nameend="col3" align="justify">¹Water reducible isocyanate available from PPG Industries</entry></row><row><entry namest="col1" nameend="col3" align="justify">²Waterbased reducer available from PPG Industries</entry></row></tbody></tgroup></table></tables>

0087Sealer coating compositions for use in the present invention were prepared as shown below:

0088The final paint had a solids content of 53% and application viscosity of 34 cPs on a Brookfield CAP 2000 spindle #1 at 900 rpm. The sealer coating composition of Example M was spray applied at ambient conditions onto 12" x 4" x 0.032" steel panels with a gray electrodeposition coating. The substrate panels were obtained from ACT Laboratories Inc., LLC of Hillsdale, Michigan. The coating composition was applied in one coat and then blown dry with a forced air knife. The dry film thickness was 28 - 38 microns. The control coating was a Refinish solvent borne sealer, ECS25, commercially available from PPG Industries, Inc. This was spray applied in two coats and was allowed to flash at ambient conditions from glossy to matte. The film thickness was about 40-45 microns.

0089After about 30 minutes, the sealer coatings were topcoated. The first layer of topcoat was a basecoat available from PPG Industries Inc., T409, applied to the panels in two coats using a forced air knife after each coat. The film thickness was 4 - 6 microns. A 2K Refinish clear coat commercially available from PPG Industries, Inc. as DC4010 was then applied over the coated panel in two coats with a flash between coats. The clear coated panels were allowed to flash overnight. The clear coat film thickness was approximately 57-60 microns.

0090Table 6 lists the results of hardness and appearance testing. <tables id="tabl0006" num="0006"><table frame="all"><title><b>Table 6. Acrylic Sealer Konig Hardness and Appearance of Coating Stack</b></title><tgroup cols="8"><colspec colnum="1" colname="col1" colwidth="28mm" align="center" /><colspec colnum="2" colname="col2" colwidth="23mm" align="center" /><colspec colnum="3" colname="col3" colwidth="11mm" align="center" /><colspec colnum="4" colname="col4" colwidth="13mm" align="center" /><colspec colnum="5" colname="col5" colwidth="13mm" align="center" /><colspec colnum="6" colname="col6" colwidth="13mm" align="center" /><colspec colnum="7" colname="col7" colwidth="13mm" align="center" /><colspec colnum="8" colname="col8" colwidth="13mm" align="center" /><thead valign="middle"><row><entry /><entry>Konig (sec)</entry><entry>du</entry><entry>Wa</entry><entry>Wb</entry><entry>Wc</entry><entry>Wd</entry><entry>We</entry></row></thead><tbody valign="middle"><row><entry>Example M</entry><entry>94</entry><entry>3.5</entry><entry>12.2</entry><entry>30.1</entry><entry>18.4</entry><entry>30.3</entry><entry>13.5</entry></row><row><entry>Control ECS25</entry><entry>64</entry><entry>1.5</entry><entry>11.1</entry><entry>26.0</entry><entry>14.3</entry><entry>20.5</entry><entry>13.1</entry></row></tbody></tgroup></table></tables>

0091It can be concluded from the data shown in Tables 3 and 6, that sealer formulas for use in the present invention have the speed of drying, as well as appearance, required to meet or exceed the solvent borne control in the refinish repair process.

Primer:

0092Primer coatings were prepared by first producing a grind paste (Example N) made with the following ingredients. The binder portion of the grind paste may consist of the dispersion of urethane-shell particles of Example D. <tables id="tabl0007" num="0007"><table frame="all"><title><b>Table 7. Grind Paste for Urethane Acrylate Primer Coating</b></title><tgroup cols="3" align="center"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="60mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><thead valign="middle"><row><entry /><entry /><entry>Example N</entry></row><row><entry>Charge</entry><entry>Name</entry><entry>Weight (g)</entry></row></thead><tbody valign="middle"><row><entry>1</entry><entry>Urethane-shell particles of Example D</entry><entry>741</entry></row><row><entry>2</entry><entry>Disperbyk 024¹</entry><entry>16</entry></row><row><entry>3</entry><entry>Dispex^® Ultra PA 4550²</entry><entry>21</entry></row><row><entry>4</entry><entry>Surfynol 104E³</entry><entry>25</entry></row><row><entry>5</entry><entry>Carbon Black</entry><entry>23</entry></row><row><entry>6</entry><entry>Titanium Dioxide</entry><entry>524</entry></row><row><entry>7</entry><entry>Barium Sulfate</entry><entry>607</entry></row><row><entry>8</entry><entry>Talc</entry><entry>432</entry></row><row><entry>9</entry><entry>Calcium Carbonate</entry><entry>238</entry></row><row><entry>10</entry><entry>DI Water</entry><entry>323</entry></row><row><entry>11</entry><entry>10 DMEA/90 DI Water</entry><entry>53</entry></row><row><entry>12</entry><entry>DI Water</entry><entry>323</entry></row><row rowsep="0"><entry namest="col1" nameend="col3" align="justify">¹Available from BYK</entry></row><row rowsep="0"><entry namest="col1" nameend="col3" align="justify">²Available from EFKA</entry></row><row><entry namest="col1" nameend="col3" align="justify">³Available from Air Products</entry></row></tbody></tgroup></table></tables>

0093The ingredients of charges 1 through 10 were first dispersed with a high speed Cowles mixer for 30 minutes. Charge 11 was added and stirring continued for 30 minutes. Charge 12 was added and the mixture was milled on a Hockmeyer Micro Mill until a 7 Hegman was achieved.

0094Primer coating compositions for use in the present invention were prepared as shown below: <tables id="tabl0008" num="0008"><table frame="all"><title><b>Table 8. Primer Coating Compositions</b></title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="60mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><colspec colnum="4" colname="col4" colwidth="22mm" /><colspec colnum="5" colname="col5" colwidth="22mm" /><thead valign="middle"><row><entry align="center" /><entry align="center" /><entry align="center">Example O</entry><entry align="center">Example P</entry><entry align="center">Example Q</entry></row><row><entry align="center">Charge</entry><entry align="center">Name</entry><entry align="center">Weight (g)</entry><entry align="center">Weight (g)</entry><entry align="center">Weight (g)</entry></row></thead><tbody valign="middle"><row><entry align="center">1</entry><entry align="center">Grind Paste of Example N</entry><entry align="center">122</entry><entry align="center">122</entry><entry align="center">122</entry></row><row><entry align="center">2</entry><entry align="center">Urethane-shell particles of Example D</entry><entry align="center">77</entry><entry align="center">77</entry><entry align="center">77</entry></row><row><entry align="center">4</entry><entry align="center">EHW8224 Hardener¹</entry><entry align="center">28</entry><entry align="center">28</entry><entry align="center">28</entry></row><row><entry align="center">5</entry><entry align="center">T494 Reducer²</entry><entry align="center">9</entry><entry align="center">17</entry><entry align="center">28</entry></row><row><entry namest="col1" nameend="col5" align="center" /></row><row><entry namest="col1" nameend="col2" align="center">% Solids</entry><entry align="center">52</entry><entry align="center">55</entry><entry align="center">57</entry></row><row><entry align="center">Viscosity</entry><entry align="center">(cPs)</entry><entry align="center">32</entry><entry align="center">40</entry><entry align="center">55</entry></row><row rowsep="0"><entry namest="col1" nameend="col5" align="justify">¹Water reducible isocyanate available from PPG Industries</entry></row><row><entry namest="col1" nameend="col5" align="justify">²Waterbased reducer available from PPG Industries</entry></row></tbody></tgroup></table></tables>

Wedge Panel

0095The sag resistance properties were tested as a function of climatic conditions against a one-component waterborne primer. The control was EPW115, a primer commercially available from PPG Industries, Inc. It was reduced by 5, 10, and 15% by weight using the same T494 Reducer as in Table 8. The primer coating compositions for use in the present invention and the control were spray applied at two atmospheric conditions onto 4" x 18" x 0.026" steel panels having a zinc phosphate pretreatment with 17 evenly spaced punched holes (Sag Panels). The Sag Panels were obtained from ACT Laboratories Inc., LLC of Hillsdale, Michigan. These Sag Panels were used to measure the capability of the coatings to resist sag by spray applying a wedge of coating. The wedge is created by moving more slowly beginning at the bottom of the panel and faster as the application continues toward the top. This results in the highest film thickness area at the bottom and lower film thickness at the top. The coatings are allowed to flash vertically for 5 minutes at ambient conditions and are then baked for 30 minutes at 60°C. The coating is assessed around the holes in the panel for the sagging. The dry film thickness is measured near the area of sag around the hole. By this method, the minimum dry film thickness at which sag occurs is recorded. <tables id="tabl0009" num="0009"><table frame="all"><title><b>Table 9. DFT at Sag (µm)</b></title><tgroup cols="4" align="center"><colspec colnum="1" colname="col1" colwidth="40mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="57mm" /><colspec colnum="4" colname="col4" colwidth="21mm" /><thead valign="middle"><row><entry><b>Application Conditions</b></entry><entry><b>Viscosity</b></entry><entry><b>Experimental (Examples O, P, Q)</b></entry><entry><b>EPW 115</b></entry></row></thead><tbody valign="middle"><row><entry /><entry>Low</entry><entry>13</entry><entry>10</entry></row><row><entry>65°F</entry><entry>Med</entry><entry>22</entry><entry>11</entry></row><row><entry>80% RH</entry><entry>High</entry><entry>39</entry><entry>15</entry></row><row><entry /><entry /><entry /><entry /></row><row><entry>77°F</entry><entry>Low</entry><entry>41</entry><entry>24</entry></row><row><entry>24% RH</entry><entry>Med</entry><entry>69</entry><entry>23</entry></row><row><entry /><entry>High</entry><entry>74</entry><entry>33</entry></row></tbody></tgroup></table></tables>

Primer Application

0096The primer coating composition of Example P was spray applied at ambient conditions onto 12" x 4" x 0.032" steel panels with a gray electrodeposition coating. The substrate panels were obtained from ACT Laboratories Inc., LLC of Hillsdale, Michigan. The control coating was a Refinish solvent borne primer commercially available from PPG Industries, Inc. as D839. The coating compositions were applied in two coats with a 5 minute ambient flash in between followed by a bake for 30 minutes at 60°C. <tables id="tabl0010" num="0010"><table frame="all"><title><b>Table 10. Primer coating Konig and Sandability Rating</b></title><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="29mm" align="center" /><colspec colnum="2" colname="col2" colwidth="26mm" align="center" /><colspec colnum="3" colname="col3" colwidth="26mm" align="center" /><thead valign="top"><row><entry /><entry>Konig (sec)</entry><entry>Sandability</entry></row></thead><tbody valign="middle"><row><entry>Example P</entry><entry>36</entry><entry>Good</entry></row><row><entry>Control D839</entry><entry>47</entry><entry>Good</entry></row></tbody></tgroup></table></tables>

0097The primer coatings were tested for Konig hardness via ASTM D4366 and through evaluation of the response to sanding. Typically a body shop will sand a primer to remove imperfections on the surface as well as to create a physical link for adhesion of the following layers. It is important to the body shop's production to be able to sand a primer very quickly after the bake process. The primers for use in the current invention were sanded with 320 grit sandpaper available from 3M using an air powered disc sander available from Hutchings Mfg. Co. within 5 minutes after the coatings were removed from the oven. The sandability is considered a pass if the coating is not sticky, the sandpaper does not clog, and a powder forms under the sandpaper.

0098It can be seen from Tables 9 and 10 that the two-component primer for use in the current invention demonstrates better sag resistance over current one-component waterborne primer at a very wide range of relative humidity. The primer of the current invention is very similar in hardness to a solvent borne control. It sands comparably to the solvent borne control when just out of the oven and cool.