Coating compositions for high efficiency applicators

Abstract

A coating composition comprising from 6% to 15% by weight of total solids based on the weight of the coating composition; from 15 wt% to 70 wt% of core-shell resin particles based on the total solids; and a volatile organic compound (VOC) content of from 50 g / L to 550 g / L, such as from 100 g / L to 500 g / L or from 150 g / L to 450 g / L. The coating composition can have a viscosity of from 30 mPa * s to 110 mPa * s at 1000 s <-1 > and a viscosity of greater than 1000 mPa * s at 0.1 s <-1 >, the viscosity being measured at 25 DEG C and a pressure of 101.3 kPa (1 atm) using an Anton-Par MCR301 rheometer equipped with a concentric cylindrical clamp (CC27, gap size of 1.13 mm). The total solids and VOCs can be determined according to ASTM D2369 (2020) and ASTM 3960 (2005), respectively. The coating composition can be applied using a precision applicator with high transfer efficiency.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority of U.S. Provisional Application No. 63 / 380,970, filed on October 26, 2022, and entitled "Coating Composition For Use In High Efficiency Applicators", which is hereby incorporated by reference. Technical Field

[0003] The present disclosure generally relates to coating compositions that can be applied using high-precision, high-efficiency applicators. Background Art

[0004] Coating compositions can be applied to a variety of substrates to provide color and other visual effects as well as various designs and patterns. For example, a coating can be applied to an automotive substrate to provide two or more different colors on different parts of the substrate. To form different designs and patterns, masking materials are typically placed on different parts of the substrate, and multiple applications of different coating compositions are applied to the substrate. Summary of the Invention

[0005] The present disclosure relates to a coating composition comprising: (a) 6 wt% to 15 wt%, such as 6 wt% to 14 wt% or 7 wt% to 13 wt% total solids, based on the weight of the coating composition; (b) 15 wt% to 70 wt%, such as 20 wt% to 65 wt% or 25 wt% to 60 wt% core-shell resin particles, based on the total solids; and (c) a volatile organic compound (VOC) content of 50 g / L to 550 g / L, such as 100 g / L to 500 g / L or 150 g / L to 450 g / L. The coating composition may have a viscosity of 30 mPa·s to 110 mPa·s, such as 40 mPa·s to 100 mPa·s or 45 mPa·s to 90 mPa·s at 1000 s -1 and a viscosity greater than 1000 mPa·s, such as greater than 2500 mPa·s or greater than 4000 mPa·s at 0.1 s -1 measured using an Anton-Paar MCR301 rheometer equipped with a concentric cylinder fixture (CC27, gap size 1.13 mm) at 25 °C and a pressure of 101.3 kPa (1 atm). Total solids ASTM D2369 (2020) and VOC ASTM D3960-05 (2005) can be determined using the referenced ASTM methods. The coating composition may be capable of being applied using a high transfer efficiency precision applicator. Detailed Embodiments

[0006] Unless otherwise specified, the temperature and pressure conditions are ambient temperature (22 °C), relative humidity of about 45%, and standard pressure of 101.3 kPa (1 atm).

[0007] Unless otherwise indicated, any term in parentheses may alternatively refer to the entire term without parentheses, the term without parentheses, and combinations of each alternative. Thus, as used herein, the term “(meth)acrylate” and similar terms are intended to include acrylate, methacrylate, and mixtures thereof.

[0008] It should be understood that the present disclosure may assume various alternative variations and sequences of steps, unless expressly provided to the contrary. Accordingly, unless otherwise indicated, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained. 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.

[0009] Although the numerical ranges and parameters setting forth the broad scope of the present disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard variations found in their respective testing measurements.

[0010] In addition, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0011] All ranges are inclusive and combinable. For example, the term “a range of 0.06 wt% to 0.25 wt%” will include each of 0.06 wt% to 0.25 wt%, 0.06 wt% to 0.08 wt%, and 0.08 wt% to 0.25 wt%. Further, when ranges are given, any endpoints and / or the numbers recited within those ranges may be combined within the scope of the present disclosure.

[0012] As used herein, unless otherwise expressly stated, all numbers such as those representing values, ranges, amounts or percentages, even if the term is not expressly present, can be interpreted as beginning with the word "about". Unless otherwise indicated, the plural encompasses the singular and vice versa. As used herein, terms such as "comprising" mean "including but not limited to". Similarly, as used herein, terms such as "on", "applied on / over", "formed on / over", "deposited on / over", "overlapped", and "provided on / over" mean formed, overlapped, deposited or provided on a surface but not necessarily in contact with the surface. For example, a coating "formed on" a substrate does not exclude the presence of one or more other coatings of the same or different compositions between the formed coating and the substrate.

[0013] As used herein, the transitional term "comprising" (and other comparable terms such as "containing" and "including") is "open-ended" and can include unspecified matters. Although described in terms of "including", the terms "consisting essentially of" and "consisting of" are also within the scope of this disclosure.

[0014] As used herein, the term "adhesion promoter" refers to any material that enhances the adhesion of a coating composition to a substrate when included in the composition.

[0015] As used herein, the terms "alkoxy-functional silicone" and similar terms refer to silicones that contain only alkoxy-functional groups --OR, where R can be an alkyl group or an aryl group.

[0016] As used herein, the terms "a" and "an" should be interpreted as including "at least one" and "one or more".

[0017] As used herein, the term "applicator" refers to any device capable of applying a coating composition to a substrate and can include but is not limited to rollers, brushes, spray tips in fluid communication with a nozzle, and high-efficiency applicators.

[0018] As used herein, the term "ASTM" refers to publications of ASTM International, West Conshohocken, PA.

[0019] As used herein, the term "base coat" refers to a coating layer applied on a primer, another base coat; and / or directly on a substrate, optionally including components (such as colorants) that affect color and / or provide other visual impacts.

[0020] As used herein, the term "adhesive" refers to a compound or mixture of compounds that is used to bind the input materials (including pigments, fillers, etc., if present) in a coating composition and adhere the coating film as a continuous film to the underlying surface.

[0021] As used herein, the term "transparent coating" refers to a coating that is at least substantially transparent or completely transparent and may not contain a colorant. The term "substantially transparent" refers to a coating where, when viewed through the coating, the surface beyond the coating is at least partially visible to the naked eye. The term "completely transparent" refers to a coating where, when viewed through the coating, the surface beyond the coating is completely visible to the naked eye. A transparent coating can be substantially free of pigments. Substantially free of pigments can refer to a "colored transparent coating", which can be a coating composition that contains less than 3 wt%, such as less than 2 wt%, less than 1 wt% or 0 wt% of pigments based on the total solids.

[0022] As used herein, the term "coating" refers to the finished product obtained by applying one or more coating compositions to a substrate and forming a coating, as a non-limiting example, by curing. A primer layer, a basecoat or a color coat layer and a transparent coating can form part of the coating. As used herein, the term "coating" is used to refer to the result of applying one or more coating compositions to a substrate in one or more coatings of such one or more coating compositions. As a non-limiting example, a single coating referred to as a "colored coating" or "topcoat" can be used to provide the functions of both a basecoat and a transparent coating and can include the result of two or more applications of a colored coating composition.

[0023] As used herein, the term "colorant" refers to any substance that imparts color and / or other opacity and / or other visual effects to a coating composition and can include, but is not limited to, dyes and pigments.

[0024] As used herein, the transitional term "comprising" (and other equivalent terms such as "containing" and "including") is "open-ended" and open to include unspecified materials. Although described in terms of "comprising", the terms "consisting essentially of" and "consisting of" are also within the scope of this disclosure.

[0025] As used herein, the term "continuous jet" refers to a continuous stream of coating from a precision applicator that is applied to a substrate to provide a knife-edge line at the end of the applied coating film.

[0026] As used herein, the term "core-shell resin particle" refers to a particle that includes a core or internal domain or surface domain that is at least partially encapsulated by a shell. Core-shell particles can have various shapes (or morphologies) and sizes. As a non-limiting example, core-shell particles can have a spherical, cubic, plate-like, polyhedral or needle-like (elongated or fibrous) morphology.

[0027] As used herein, the term "crosslinking" refers to a bond or sequence of short bonds that connects one polymer chain to another. "Highly crosslinked" refers to a situation where the amount of crosslinking causes the polymer to be swellable to some extent but not soluble in a solvent or water at 0.05 wt% at 25 °C.

[0028] As used herein, the term "crosslinking agent" refers to a molecule or polymer containing a functional group that reacts with a crosslinking functional group of a polymer and / or resin in a coating composition.

[0029] As used herein, the term "crosslinking functional group" refers to a functional group located in the main chain of a polymer, usually in a group pendant to the main chain of the polymer, at the end on the main chain of the polymer, or a combination thereof, where such a functional group is capable of reacting with other crosslinking functional groups or a separate crosslinking material during curing to produce a crosslinked coating.

[0030] As used herein, the terms "curable", "cured", etc. in connection with a coating composition mean that at least a portion of the components making up the coating composition are polymerizable and / or crosslinkable when exposed, as a non-limiting example, to a higher temperature (greater than 25 °C) or ultraviolet radiation.

[0031] As used herein, the term "droplet" refers to a column of liquid completely surrounded by a free surface.

[0032] As used herein, the term "droplet" refers to droplets of a coating composition from a precision applicator, the droplets being spaced far enough apart to reduce the volume of material applied, but close enough together to flow together and provide conformal coating coverage.

[0033] As used herein, "drop-on-demand" refers to a precision applicator that controls the volume of individual drops and dispenses such drops only when instructed to do so.

[0034] As used herein, the term "dried" or "drying" refers to the removal of volatile compounds from a film, coating, or applied coating.

[0035] As used herein, the term "dye" refers to a colored substance, which in many cases is an organic compound, that can be chemically bonded to a substrate or another component in a coating composition.

[0036] As used herein, the term "film-forming" material refers to the film-forming component of a coating composition and can include a polymer, resin, crosslinking material, or any combination thereof that is a film-forming component of the coating composition. The film-forming material can be dried or cured.

[0037] As used herein, the term "flow rate" refers to the volume of coating composition leaving an applicator per unit time (e.g., cm3 ( / min).

[0038] As used herein, the term "completely transparent" refers to a coating where, when viewed through the coating, the surface beyond the coating is completely visible to the naked eye.

[0039] As used herein, the term "gel" refers to a solution where the storage modulus G' is greater than the loss modulus G", i.e., tan(δ) (tan(δ) = G" / G') is less than 1, where the G' and G" values are measured at ω = 1 rad / s and γ = 1% at each concentration.

[0040] As used herein, the terms "gel transition" and "weight % NV (non-volatile matter)" refer to the concentration of the resin or total solids when the solution becomes a gel, i.e., when G' is greater than G", or in other words, the concentration or weight % NV when the loss modulus tan(δ) (tan(δ) = G" / G') is less than 1.

[0041] As used herein, the term "efficient applicator" refers to a precision application device that may be capable of applying a coating composition to at least a portion of a substrate without overspraying, as a non-limiting example, a transfer efficiency greater than 85%.

[0042] Unless otherwise specified, as used herein, the term "insoluble" refers to a substance (solid) that does not dissolve in a solvent or water (as indicated) even after being mixed at 0.05 wt% at 25°C.

[0043] Unless otherwise specified, as used herein, the term "molecular weight" refers to the weight-average molecular weight determined by gel permeation chromatography (GPC) using appropriate polystyrene standards. If the number-average molecular weight is specified, the weight is determined in the same GPC manner while calculating the number average based on the polymer molecular weight distribution data obtained therefrom.

[0044] As used herein, the terms "multicomponent", "multi-K", and "multi-pack" refer to a coating composition that contains a first component containing a crosslinkable resin, a second component containing a crosslinking agent, and additional components that may or may not contain a crosslinkable resin or a crosslinking agent, where these components are stored separately before use. The crosslinkable resin and the crosslinking agent are capable of reacting when combined to form a thermosetting composition. When the multicomponent coating composition does not contain additional components, the coating composition is a two-component coating composition.

[0045] As used herein, the term "nozzle" refers to a part of an applicator having an opening through which the coating composition is ejected or jetted, and unless otherwise specified, the term "nozzle" may be used interchangeably with any of a valve jet or a piezoelectric, thermal, acoustic, or ultrasonic actuated valve jet or nozzle.

[0046] As used herein, "overspray" refers to the portion of a coating composition that does not land within the target area.

[0047] As used herein, the terms "one-component", "1-K", and "1-pack" refer to coating compositions in which all coating components are maintained in the same package after manufacture, during transportation, and during storage. As a non-limiting example, even if a solvent is added to a 1-K composition to reduce its viscosity or solids, the coating composition is considered a 1-K coating composition.

[0048] As used herein, the term "organic solvent" refers to a carbon-based material that is capable of dissolving or dispersing other substances.

[0049] As used herein, the term "overlap" refers to the amount of coating composition in a path width applied over a coating composition of a previous path width.

[0050] Unless otherwise specified, the term "particle size" refers to the Z-average particle size of particles in an aqueous dispersion determined using a Zetasizer dynamic light scattering instrument (available from Malvern Panalytical Ltd.) with a high-performance dual-angle particle size analyzer.

[0051] As used herein, the term "path width" refers to the distance perpendicular to the direction of movement of an applicator that applies a coating composition to a substrate.

[0052] As used herein, the term "pigment" refers to an organic or inorganic material, or a combination thereof, which may be a colored material, insoluble in a solvent, and which may also be functional. Non-limiting examples are anti-corrosion pigments or effect pigments, and non-limiting examples include mica and aluminum.

[0053] As used herein, the prefix "poly" refers to two or more. As a non-limiting example, polyisocyanate refers to a compound containing two or more isocyanate groups, and polyol refers to a compound containing two or more hydroxyl groups.

[0054] As used herein, the term "polyisocyanate" refers to blocked (or capped) polyisocyanates as well as unblocked polyisocyanates.

[0055] As used herein, the term "polymer" includes homopolymers (formed from one monomer) and copolymers formed from two or more different monomer reactants or containing two or more different repeating units. In addition, the term "polymer" includes prepolymers and oligomers.

[0056] As used herein, the term "primer coat" refers to an undercoat that can be applied to a substrate to prepare the surface for the application of a protective or decorative coating composition.

[0057] As used herein, the term "rheology modifier" refers to a material that modifies the rheology or flow characteristics of a fluid composition to which it is added, and may include, but is not limited to, natural gums, synthetic resins, organoclays, hydrogenated castor oil, fumed silica, polyamides, associative thickeners, overbased sulfonates (as a non-limiting example, calcium colloidal sulfonate dispersed in oil, where the excess sulfonate acts as a surfactant), inorganic crystals, non-aqueous microgels, and polyurea compounds insoluble in organic solvents.

[0058] As used herein, the term "sag" refers to the downward movement of a coating composition that may occur after the coating composition has been applied to a substrate and before the coating composition has solidified, cured, and / or dried. Non-limiting examples include drip lines, sag curtains, torn drops, or other defects and variations in the coating that result in an uneven coating surface, as tested according to ASTM D4400 (2018). Sag can be measured in mm using a ruler. Dripping or wing-like defects in the coating can be seen below the panel holes. ASTM D4400 recommends a sag limit of 1.6 mm (distance between the sag lines). As used herein, "no sag" refers to a situation where no visible drops or wing-like defects are present, and "minimum sag" refers to a situation where there are no drops or wing-like defects exceeding 5 mm between the sag lines.

[0059] As used herein, the term "shear strain" refers to the deformation or flow of a coating composition in response to an applied shear stress.

[0060] As used herein, the term "shear stress" refers to the pressure applied to the surface of a coating composition.

[0061] As used herein, the term "shear thinning" refers to the non-Newtonian behavior of a fluid whose viscosity decreases under increasing shear stress.

[0062] As used herein, the term "flow" refers to a flowing liquid, and in many cases, a flowing coating composition.

[0063] As used herein, the terms "silicone" and similar terms refer to polysiloxane polymers based on a structure containing alternating silicon and oxygen atoms. As used herein, "silicone" and "siloxane" are used interchangeably.

[0064] As used herein, the term "silanol-functional silicone" and similar terms refer to a silicone containing a silanol functional group --SiOH.

[0065] As used herein, the term "substrate" refers to the surface of an article to be coated, and may refer to a coating disposed on the article, and the article is also considered a substrate.

[0066] As used herein, the term "target area" means a portion of the surface area of any substrate to be coated in the application of a coating composition such as a first coating composition, a second coating composition, or a third coating composition. The target area will typically not include the entire surface area of a given substrate. The term "non-target area" means the remaining portion of the surface area of the substrate and includes all areas outside the substrate. When applying multiple coating compositions, the target area and the non-target area can be different for each application of a coating composition.

[0067] As used herein, the term "thermosetting" means a polymer or resin having functional groups that react with functional groups in a crosslinking agent or another polymer or molecule to form a network material, irreversibly transforming a "soft" polymer into a more rigid form. Thermosetting refers in many cases to a resin that "cures" irreversibly upon curing or crosslinking, where the polymer chains of the resin are linked together by covalent bonds. Once cured or crosslinked, a thermosetting resin will not melt upon application of heat and is insoluble in most organic solvents.

[0068] As used herein, the term "thermoplastic" refers to polymers and resins that are not linked by covalent bonds and can therefore undergo liquid flow upon heating and are soluble in certain solvents.

[0069] As used herein, the term "tip speed" refers to the speed at which an applicator traverses the surface of a substrate.

[0070] As used herein, the term "total solids" or "solids" or "solids content" means the solids content as determined according to ASTM D2369 (2020).

[0071] As used herein, the term "use conditions" means all temperatures and pressures, including ambient pressure such as 101.3 kPa (1 atm), and the temperatures at which any coating composition is used, stored, or applied, and can include temperatures as low as -10 °C and as high as 140 °C.

[0072] As used herein, the term "transfer efficiency" means the weight percentage of the coating composition applied to a substrate compared to the weight of the coating composition leaving the applicator, as determined according to ASTM D5286-20.

[0073] As used herein, the term "topcoat" means the uppermost coating applied over another coating such as a primer coat to provide a protective layer and / or a decorative layer.

[0074] As used herein, the terms "two-component", "2-K", and "2-pack" refer to coating compositions that comprise a first component containing a crosslinkable resin and a second component containing a crosslinking agent, where the first and second components are stored separately prior to use. The crosslinkable resin and the crosslinking agent are capable of reacting when combined to form a thermosetting composition.

[0075] As used herein, the term "vehicle" is used in its broadest sense and includes all types of vehicles such as, but not limited to, automobiles, minivans, SUVs (sport utility vehicles), trucks, semi-trailer trucks; tractors, buses, vans, golf carts, motorcycles, bicycles, trams, trailers, ATVs (all-terrain vehicles); pickup trucks; heavy haulers such as bulldozers, mobile cranes, and excavators; airplanes; boats; ships; and other modes of transportation.

[0076] As used herein, unless otherwise specified, the term "viscosity" refers to a value determined at 25 °C and ambient pressure and reflects the resistance of a fluid to flow when subjected to shear stress and / or shear strain.

[0077] As used herein, the term "volatile" refers to materials that readily evaporate under ambient conditions.

[0078] As used herein, the phrase "wt%" refers to weight percentage.

[0079] Recent advances in precision applicator technology (non-limiting examples are the EcoPaintJet available from Dürr Systems AG) enable applicators to apply coatings with transfer efficiencies approaching 100% without masking, thereby enabling the ability to achieve fine edge details. Typically, to obtain proper jet stream deposition, these applicators require an output of at least 100 µm wet film coating thickness. Many vehicle applications require a dry film thickness of an aqueous primer coat to be typically less than 20 µm, such as 12 µm - 15 µm. These requirements indicate that the maximum solids volume of a precision-applied aqueous primer coat is less than 15 wt%.

[0080] One way to meet this requirement is to reduce the solids of an aqueous primer coat known to be spray-applied to 15 wt% or less; however, the resulting coating's Newtonian rheology can lead to undesirable properties such as unacceptable sagging when applied to vertical substrates.

[0081] The present disclosure provides a pH-sensitive latex having a low solids content, thereby providing desirable shear-thinning rheological behavior, thus minimizing the need for other rheology control additives to properly form a smooth horizontal film and desirable vertical sag resistance.

[0082] The present disclosure provides coating compositions comprising:

[0083] 6 wt % to 15 wt %, such as 6 wt % to 14 wt %, based on the weight of the coating composition

[0084] or 7 to 13 wt % total solids;

[0085] 15 to 70 wt % based on total solids, such as 20 to 65 wt % or 25 wt %

[0086] to 60 wt % core-shell resin particles; and

[0087] A volatile organic compound (VOC) content of 50 g / L to 550 g / L, such as 100 g / L to 500 g / L or 150 g / L to 450 g / L;

[0088] The coating composition was 1000s -1 The viscosity may be 30 mPa·s to 110 mPa·s, such as 40 mPa·s to 100 mPa·s or 45 mPa·s to 90 mPa·s, and at 0.1 s -1 The coating composition may have a viscosity greater than 1000 mPa·s, such as greater than 2500 mPa·s or greater than 4000 mPa·s and up to 50,000 mPa·s, measured at 25°C and a pressure of 101.3 kPa (1 atm) using an Anton-Paar MCR301 rheometer equipped with a concentric cylindrical fixture (CC27, bob diameter of 26.66 mm, cup diameter of 28.92 mm and gap size of 1.13 mm). Total solids and VOC are determined according to ASTM D3960 (2005). As a non-limiting example, a high transfer efficiency precision applicator may be used to apply the coating composition.

[0089] The core-shell resin particles may include polymer microparticles or nanoparticles having a core / shell structure. The core (inner domain) and shell (surface domain) polymers may be chemically bonded, physically associated, and / or covalently attached to each other, and the polymer particles may be formed by stepwise emulsion polymerization of ethylenically unsaturated monomers. The following examples show non-limiting examples of the polymerization method. The core may account for 2 wt% to 98 wt% of the polymer microparticles, such as 65 wt% to 90 wt% or 75 wt% to 85 wt%, while the shell may account for 2 wt% to 98 wt% of the polymer particles, such as 10 wt% to 35 wt% or 15 wt% to 25 wt%. In addition, by using monomers having multiple ethylenically unsaturated groups, the core can be internally crosslinked, a non-limiting example being ethylene glycol dimethacrylate. These internal crosslinking monomers can be used in an amount of up to 10 wt%, such as 3 wt% to 10 wt%. The shell polymer can be designed to be more polar than the core by using polar monomers having functional groups (non-limiting examples being hydroxyl and acid groups). As a non-limiting example, the shell polymer can be formed from acid-functional ethylenically unsaturated monomers in an amount sufficient to allow the polymer particles to be dispersed in an aqueous medium. Monomers having functional groups can be included in the monomer solution for forming the shell in an amount of 20 wt% to 40 wt% of the monomers for preparing the shell, such as 25 wt% to 35 wt%.

[0090] As a non-limiting example, the above-mentioned core-shell resin particles may include such core-shell resin particles that when dispersed in an aqueous medium at a solids content of greater than 0 wt% to less than 14 wt%, such as 1 wt% to 13 wt%, 2 wt% to 13 wt%, or 3 wt% to 12 wt%, and at a pH of 8 to 8.7, such as 8.2 to 8.6 or 8.3 to 8.5, a viscoelastic gel having a G' value greater than the G'' value measured at ω = 1 rad / s and γ = 1% at 25 °C and a pressure of 101.3 kPa (1 atm) using an Anton-Paar MCR301 rheometer equipped with a 50 mm cone-plate fixture can be formed. In other words, the loss modulus tan(δ) (tan(δ) = G'' / G') becomes less than 1.

[0091] As a non-limiting example, the core-shell resin particles may include

[0092] a core obtained by polymerizing a monomer mixture that includes

[0093] 0 wt% to 99 wt%, such as 95 wt% to 99 wt% or 96 wt% to 99 wt%, of a first nonionic monomer conforming to the following formula:

[0094] R 1 2 C=CR 1 -C(O)-W-R 6

[0095] where each R 1 is independently -H, -CH 3 or -CH 2 CH 3 ;

[0096] W is selected from O, NR 4 and S; each R 1 is independently -H, -CH 3 or -CH 2 CH 3 ;

[0097] R 4 is H, CH 3 or CH 2 CH 3 ; and

[0098] R 6 is selected from C 1 to C 12 alkyl, C 5 to C 12 alicyclic group and C 6 to C 12 aromatic group or alkyl aromatic group, and may optionally include one or more -OH substitutions of hydrogen;

[0099] 0 wt% to 4 wt%, such as 1 wt% to 4 wt% or 1 wt% to 3 wt% of a carboxylic acid monomer conforming to the following formula:

[0100] R 2 2 C=CR 2 -C(O)-OH

[0101] where each R 2 is independently -H, -CH 3 or -CH 2 CH 3 ; and

[0102] 0 wt% to 100 wt%, such as 20 wt% to 90 wt% or 20 wt% to 80 wt% of a vinyl monomer conforming to the following formula:

[0103] R 1 2 C=CR 1 -A-C(O)-R 9

[0104] where each R 1 is independently -H, -CH 3 or -CH 2 CH 3 ;

[0105] A is NR 4 or O;

[0106] R 4 is H, CH 3 or CH 2 CH 3 ; and

[0107] R 9 is a straight-chain or branched alkyl group having 1 to 18 carbon atoms, or when A is nitrogen, R 9 is bonded to A to form a 5- to 7-membered ring;

[0108] A shell obtained from a monomer mixture comprising

[0109] 0 wt% to 40 wt%, such as 2 wt% to 30 wt% or 5 wt% to 20 wt%, of a second nonionic monomer conforming to the formula:

[0110] R 1 2 C=CR 1 -C(O)-Z-R 7

[0111] wherein each R 1 is independently -H, -CH 3 or -CH 2 CH 3 ;

[0112] Z is selected from O, NR 4 , S and a group according to the formula

[0113] -(O-CR 8 -CR 8 -) n -O-

[0114] wherein each R 8 is independently -H, -CH 3 or -CH 2 CH 3 ; and n is from 0 to 30, such as from 0 to 25 or from 1 to 25;

[0115] R 7 is selected from C 1 to C 18 alkyl, C 5 to C 12 alicyclic group and C 6 to C 18 aromatic group or alkylaromatic group, and may optionally include one or more -OH substitutions of hydrogen;

[0116] R4 is H, CH 3 or CH 2 CH 3 ; and

[0117] 2 wt% to 50 wt%, such as 20 wt% to 50 wt%, 15 wt% to 50 wt% or 15 wt% to 40 wt% of a carboxylic acid monomer conforming to the following formula:

[0118] R 2 2 C=CR 2 -C(O)-OH

[0119] where each R 2 is independently -H, -CH 3 or -CH 2 CH 3 ; and

[0120] 0 wt% to 50 wt%, such as 0 wt% to 40 wt% or 10 wt% to 40 wt% of a vinyl monomer conforming to the following formula:

[0121] R 1 2 C=CR 1 -A-C(O)-R 9

[0122] where each R 1 is independently -H, -CH 3 or -CH 2 CH 3 ;

[0123] A is NR 4 or O;

[0124] R 4 is H, CH 3 or CH 2 CH 3 ; and

[0125] R 9 is a straight-chain or branched alkyl group having 1 to 18 carbon atoms, or when A is nitrogen, R 9 is bonded to A to form a 5- to 7-membered ring.

[0126] As a non-limiting example, in a vinyl monomer conforming to the following formula:

[0127] R 1 2 C=CR 1 -A-C(O)-R 9

[0128] After incorporation into either or both of the core and the shell of the core-shell resin particles, the incorporated residue can be hydrolyzed to leave a hydroxyl group (if A is oxygen) or an amine group (if A is nitrogen).

[0129] As a non-limiting example, the first nonionic monomer can be selected from alkyl esters of (meth)acrylic acid. Non-limiting examples of suitable (meth)acrylates include ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate; cyclic esters such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate.

[0130] As a non-limiting example, the first nonionic monomer can be selected from amides and alkylamides of (meth)acrylic acid. Non-limiting examples of suitable (meth)acrylamides include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-n-butyl(meth)acrylamide, N-isobutyl(meth)acrylamide, N-tert-butyl(meth)acrylamide, N-2-ethylhexyl(meth)acrylamide, N-lauryl(meth)acrylamide; N-cyclohexyl(meth)acrylamide and N-isobornyl(meth)acrylamide.

[0131] Any combination of the above monomers can be used as the first nonionic monomer.

[0132] As a non-limiting example, the carboxylic acid monomer can be selected from acrylic acid, α-methylacrylic acid, β-methylacrylic acid, 2-ethyl-prop-2-enoic acid, 1-ethyl-prop-2-enoic acid, α,α-dimethylacrylic acid, β,β-dimethylacrylic acid, α,β-dimethylacrylic acid and combinations thereof.

[0133] As a non-limiting example, the vinyl monomer can be selected from vinyl acetate, vinyl formate, vinyl propionate, N-vinylacetamide, N-methyl-N-vinylacetamide, N-vinylformamide, N-methyl-N-vinylformamide, 2-ethyl-5-methyl-5-vinyl-tetrahydrofuran, 5-vinyl-tetrahydrofuran, 2-methyl-2-vinyl-tetrahydrofuran and combinations thereof.

[0134] As a non-limiting example, the second nonionic monomer may be selected from ethyl (meth)acrylate; propyl (meth)acrylate; n-butyl (meth)acrylate; isobutyl (meth)acrylate; tert-butyl (meth)acrylate; 2-ethylhexyl (meth)acrylate; lauryl (meth)acrylate; cyclohexyl (meth)acrylate; isobornyl (meth)acrylate; (meth)acrylamide; N-methyl(meth)acrylamide; N-ethyl(meth)acrylamide; N,N-dimethyl(meth)acrylamide; N-propyl(meth)acrylamide; N-n-butyl(meth)acrylamide; N-isobutyl(meth)acrylamide; N-tert-butyl(meth)acrylamide; N-2-ethylhexyl(meth)acrylamide; N-lauryl(meth)acrylamide; N-cyclohexyl(meth)acrylamide; N-isobornyl(meth)acrylamide; and alkyl polyalkylene glycol (meth)acrylates, wherein the alkyl group may be a straight-chain, branched-chain or cyclic alkyl group of 1 to 22, such as 2 to 20 or 4 to 18 carbon atoms and the polyalkylene glycol has 1 to 40, such as 2 to 30 or 4 to 25 repeating units selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, hexylene glycol and combinations thereof.

[0135] As a non-limiting example, the coating composition described herein may comprise an aqueous carrier. When the coating composition comprises an aqueous carrier, the coating composition may comprise 60 wt% to 93 wt%, such as 70 wt% to 90 wt% or 80 wt% to 90 wt% water.

[0136] As a non-limiting example, the coating composition described herein may have a pH of 7.5 to 10, such as 7.6 to 9.6, 8 to 8.7 or 8.5 to 8.7. As a non-limiting example, the carboxylic acid functional groups in the core-shell resin particles may be at least partially neutralized with a base (such as a volatile amine) (i.e., at least 30% of the total neutralization equivalents) to form salt groups. A volatile amine refers to an amine compound having an initial boiling point less than or equal to 250 °C as measured under standard conditions. Non-limiting examples of suitable volatile amines include ammonia, dimethylamine, trimethylamine, monoethanolamine and dimethylethanolamine.

[0137] Without being bound by any single theory, increasing the pH of the dispersion causes the shell of the core-shell resin particles to swell and enables it to desirably alter the rheology of the coating composition.

[0138] The object of the coating composition according to the present disclosure is to minimize or eliminate the addition of a rheology modifier. When included in the coating composition, the coating composition may include a rheology modifier. Non-limiting examples of suitable rheology modifiers include thixotropic agents such as bentonite clay, urea-containing compounds, layered silicate solutions and gels in propylene glycol, acrylic alkali-swellable emulsions (ASEs), associative thickeners such as nonionic hydrophobically modified ethylene oxide urethane block copolymers (referred to herein as "HEURs") or hydrophobically modified acrylic alkali-swellable emulsions (HASEs), hydrophobically modified hydroxyethyl cellulose (HMHEC), copolymers of ethylene and vinyl acetate (EVA wax), and combinations thereof. Based on the total weight of the coating composition, the coating composition may include a rheology modifier in an amount of 20 wt%, 0.01 wt% to 10 wt%, alternatively 0.05 wt% to 5 wt% or alternatively 0.05 wt% to 0.1 wt% of the total solids of the coating composition. Suitable coating compositions may include a layered silicate propylene glycol solution, an ASE, or a combination thereof. The layered silicate propylene glycol solution includes a synthetic layered silicate, water, and polypropylene glycol. Non-limiting examples of suitable synthetic layered silicates include LAPONITE™ RD, LAPONITE™ RDS, LAPONITE™ S482, and LAPONITE™ SL25 layered silicate compositions (Altana AG of Wesel, DE). Non-limiting examples of suitable ASEs are VISCALEX™ HV 30 (BASF Corporation of Florham Park, NJ).

[0139] Suitable coating compositions can include hydrophobically modified ethoxylated urethane (HEUR) associative thickeners, which can be branched and branched HEURs formed by reacting polyethylene glycol, hydrophobic alcohols, diisocyanates, and triisocyanates together in a one-pot reaction, non-limiting examples of which are described in U.S. Patent Application Publication 2009 / 0318595A1 to Steinmetz et al.; or those formed by polymerizing polyisocyanate branching agents, water-soluble polyalkylene glycols with Mw (using GPC with polyethylene glycol standards) of 2000 to 11,000 g / mol, and diisocyanates in a solvent-free melt in the absence of catalysts such as bismuth octoate, as described in U.S. Patent No. 9,150,683 to Bobsein et al. Hydrophobic alcohols used to prepare HEUR can include, as non-limiting examples, alcohols having a carbon number range of 3 to 24, such as 5 to 20 or 10 to 25, such as octanol, dodecanol, tetradecanol, hexadecanol, cyclohexanol, phenol, cresol, octylphenol, nonylphenol, dodecylphenol, triphenylethylene phenol, ethoxylated triphenylethylene phenol, monomethyl ether of ethylene glycol, monoethyl ether of ethylene glycol, monobutyl ether of ethylene glycol, monomethyl ether of diethylene glycol, monoethyl ether of diethylene glycol, monobutyl ether of diethylene glycol; alkyl and alkaryl polyether alcohols, such as linear or branched alkanol / ethylene oxide and alkylphenol / ethylene oxide adducts, for example, lauryl alcohol, tert-octylphenol, or nonylphenol ethylene oxide adducts containing 1 - 250 ethylene oxide groups; and other alkyl, aryl, and alkaryl hydroxy compounds or combinations thereof. Branching agents can include, as non-limiting examples, triisocyanates, such as 1,6,11-undecane triisocyanate; isocyanurates, such as isophorone diisocyanate isocyanurate; and biurets, such as tris(hexyl isocyanate) biuret; Hydrophobic end-capping agents can include, as non-limiting examples, at least one of n-octanol, n-nonanol, n-decanol, n-undecanol, n-dodecanol, 2-ethylhexanol, 2-butyl-1-octanol, or 3,7-dimethyl-1-octanol.

[0140] As non-limiting examples, when included, rheology modifiers can be selected from inorganic thixotropic agents, acrylic alkali-swellable emulsions (ASEs), hydrophobically modified ethylene oxide urethane block copolymers (HEURs), hydrophobically modified alkali-swellable emulsions (HASEs), and hydrophobically modified hydroxyethyl cellulose (HMHECs), copolymers of ethylene and vinyl acetate (EVA waxes), and mixtures thereof.

[0141] When included in the coating composition, the rheology modifier can be included in an amount of 0 wt% to 10 wt%, such as 1 wt% to 9 wt% or 1 wt% to 7.5 wt% based on the total solids of the coating composition.

[0142] The coating compositions described herein may comprise a film-forming polymer or resin comprising at least one crosslinkable functional group, and a crosslinking material comprising at least one functional group reactive with the crosslinkable functional group.

[0143] In many cases, the polymers and resins may have crosslinkable functional groups. Non-limiting examples of suitable crosslinkable functional groups include urethane, carboxylic acid, alkoxysilane, hydroxyl group, carboxyl group, epoxy group, UV curable functional groups, and combinations thereof. The polymers and resins may be used alone, or two or more may be combined. As a non-limiting example, when included in the coating composition, the film-forming polymer or resin comprises a crosslinkable functional group selected from hydroxyl group, carboxyl group, and amine group.

[0144] The polymers and resins included as film-forming components in the coating composition include those commonly used in coating compositions. Non-limiting examples of suitable polymers and resins include acrylic resins, polyester resins, alkyd resins, polyurethane resins, polyolefin resins, silanes, epoxy resins, and silicone resins and combinations thereof. The number average molecular weight of the polymers and resins included as film-forming components in the coating composition can be at least 250 g / mol, such as at least 500 g / mol, at least 750 g / mol, and at least 1,000 g / mol, and can be up to 500,000 g / mol, such as up to 100,000 g / mol, up to 50,000 g / mol, up to 20,000 g / mol, and up to 10,000 g / mol and can be from 250 g / mol to 500,000 g / mol, such as from 500 g / mol to 500,000 g / mol, from 750 g / mol to 500,000 g / mol, from 1,000 g / mol to 500,000 g / mol, from 250 g / mol to 100,000 g / mol, from 500 g / mol to 100,000 g / mol, from 750 g / mol to 100,000 g / mol, from 1,000 g / mol to 100,000 g / mol, from 250 g / mol to 50,000 g / mol, from 500 g / mol to 50,000 g / mol, from 750 g / mol to 50,000 g / mol, from 1,000 g / mol to 50,000 g / mol, from 250 g / mol to 20,000 g / mol, from 500 g / mol to 20,000 g / mol, from 750 to 20,000 g / mol, from 1,000 g / mol to 20,000 g / mol, from 250 g / mol to 10,000 g / mol, from 500 g / mol to 10,000 g / mol, from 750 to 10,000 g / mol, from 1,000 to 10,000 g / mol.The weight-average molecular weight of the polymers and resins included as film-forming components in the coating composition may be at least 500 g / mol, such as at least 800 g / mol, at least 1,200 g / mol, and at least 2,000 g / mol and may be up to 500,000 g / mol, such as up to 200,000 g / mol and up to 50,000 g / mol and may be from 500 g / mol to 500,000 g / mol, such as from 800 g / mol to 500,000 g / mol, from 1,200 to 500,000 g / mol, from 2,000 to 500,000 g / mol, from 500 g / mol to 200,000 g / mol, from 800 g / mol to 200,000 g / mol, from 1,200 g / mol to 200,000 g / mol, from 2,000 g / mol to 200,000 g / mol, from 500 g / mol to 50,000 g / mol, from 800 g / mol to 50,000 g / mol, from 1,200 g / mol to 50,000 g / mol, and from 2,000 g / mol to 50,000 g / mol. The number-average molecular weight and the weight-average molecular weight of the polymers and resins included as film-forming components in the coating composition may be any value or range between (and including the end values) any of the above values.

[0145] A suitable class of film-forming polymers for film-forming resins includes, but is not limited to, those derived from ethylenically unsaturated monomers. Particularly useful members of this class are acrylic polymers, such as polymers or copolymers of alkyl esters of (meth)acrylic acid optionally together with other ethylenically unsaturated monomers. These polymers may be thermosetting and crosslinkable. Suitable (meth)acrylates include, but are not limited to, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate. Cyclic esters such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate and hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate may also be used. Additionally, vinyl aliphatic or vinyl aromatic compounds such as (meth)acrylonitrile, styrene, vinyl acetate, vinyl propionate and vinyl toluene may be used. For crosslinking, suitable functional monomers to be used in addition to the above include (meth)acrylic acid, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, N-(alkoxymethyl) and (meth)acrylamide, where, as non-limiting examples, the alkoxy group may be a butoxy group, glycidyl acrylate and / or glycidyl methacrylate.

[0146] As a non-limiting example, the film-forming resin may include a polyester polyol, which can be prepared in a known manner by the condensation of a polyol and a polycarboxylic acid. Suitable polyols include ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, glycerol, trimethylolpropane, and pentaerythritol. Suitable polycarboxylic acids include succinic acid, adipic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and trimellitic acid. In addition to the above polycarboxylic acids, functional equivalents of acids (such as acid anhydrides in the presence thereof) or C 1 -C 6 alkyl esters (such as methyl esters) can also be used.

[0147] As a non-limiting example, the film-forming resin may include an acrylic polyol, which can be prepared from a monomer mixture containing a hydroxy-functional monomer. Mixtures of different acrylic polyols can be used. The hydroxy-functional monomer may contain a hydroxyalkyl group. Suitable acrylic polyols include copolymers of alkyl esters of (meth)acrylic acid optionally together with other polymerizable ethylenically unsaturated monomers.

[0148] Non-limiting examples of hydroxy-functional monomers that can be used in acrylic polyols include (meth)acrylic acid hydroxyalkyl esters, which typically have 2 to 12 carbon atoms in the hydroxyalkyl group, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 9-hydroxynonyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 11-hydroxyundecyl (meth)acrylate, 12-hydroxydodecyl (meth)acrylate, etc.; (4-(hydroxymethyl)cyclohexyl)methyl (meth)acrylate; hydroxy-functional adducts of caprolactone and (meth)acrylic acid hydroxyalkyl esters, and reaction products of β-hydroxy ester-functional monomers, glycidyl methacrylate, and tertiary carbonic acids, and Cardura TMReaction product of E10p glycidyl ester (available from Hexion) with methacrylic acid. Based on the total weight of the monomers in the monomer mixture used to prepare the acrylic polyol, the hydroxy-functional monomer can be at least 5 wt%, such as at least 10 wt% and at least 15 wt%, and can be up to 70 wt%, up to 60 wt%, up to 50 wt%, up to 45 wt% and up to 40 wt% and can be from 5 wt% to 70 wt%, such as from 10 wt% to 70 wt%, from 15 wt% to 70 wt%, from 5 wt% to 60 wt%, from 10 wt% to 60 wt%, from 15 wt% to 60 wt%, from 5 wt% to 50 wt%, from 10 wt% to 50 wt%, from 15 wt% to 50 wt%, from 5 wt% to 40 wt%, from 10 wt% to 40 wt% and from 15 wt% to 40 wt% and is included in the monomer mixture in an amount. The amount of the hydroxy-functional monomer used in the acrylic polyol can be any value or range between any of the values recited above (and including).

[0149] The weight average molecular weight of the acrylic polyol can be at least 1,000 g / mol, such as at least 2,000 g / mol, at least 3,000 g / mol, at least 5,000 g / mol, and at least 5,500 g / mol, and can be up to 50,000 g / mol, such as up to 30,000 g / mol, up to 15,000 g / mol, up to 10,000 g / mol, and up to 7,500 g / mol and can be from 1,000 g / mol to 50,000 g / mol, such as 1,000 g / mol to 30,000 g / mol, 1,000 g / mol to 15,000 g / mol, 1,000 g / mol to 10,000 g / mol, 1,000 g / mol to 7,500 g / mol, 2,000 g / mol to 50,000 g / mol, 2,000 g / mol to 30,000 g / mol, 2,000 g / mol to 15,000 g / mol, 2,000 g / mol to 10,000 g / mol, 2,000 g / mol to 7,500 g / mol, 3,000 g / mol to 50,000 g / mol, 3,000 g / mol to 30,000 g / mol, 3,000 g / mol to 15,000 g / mol, 3,000 g / mol to 10,000 g / mol, 3,000 g / mol to 7,500 g / mol, 5,000 g / mol to 50,000 g / mol, 5,000 g / mol to 30,000 g / mol, 5,000 g / mol to 15,000 g / mol, 5,000 g / mol to 10,000 g / mol, and 5,000 g / mol to 7,500 g / mol. The weight average molecular weight as reported herein can be determined by gel permeation chromatography (GPC) using suitable polystyrene standards. The weight average molecular weight of the acrylic polyol can be any value or range between (and including) any of the values recited above.

[0150] Useful alkyl esters of (meth)acrylic acid include, but are not limited to, aliphatic alkyl esters containing from 1 to 30 carbon atoms, and typically 2 to 18 carbon atoms in the alkyl group. Non-limiting examples include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Other suitable copolymerizable ethylenically unsaturated monomers include vinyl aromatic compounds, such as styrene and vinyltoluene; nitriles, such as (meth)acrylonitrile; vinyl and vinylidene halides, such as vinyl chloride and vinylidene fluoride, and vinyl esters, such as vinyl acetate.

[0151] The film-forming resin can include polyesters and polyesters functionalized with urethane.

[0152] Non-limiting examples of suitable crosslinking agents include: diisocyanates, dihydrazides, diepoxides, and condensates of formaldehyde with nitrogen-containing compounds such as urea, thiourea, melamine, or benzoguanamine, or lower alkyl ethers of such condensates (where the alkyl group typically contains 1 to 4 carbon atoms), commonly referred to as aminoplastics. Other non-limiting examples of crosslinking agents are melamine-formaldehyde condensates (melamine resins), in which a substantial proportion of the hydroxymethyl groups have been etherified by reaction with butanol or alcohols such as ethanol or methanol, carbodiimides, polyols, phenolic resins, epoxy resins, β-hydroxy(alkyl)amide resins, hydroxy(alkyl)urea resins, oxazolines, alkylated urethane resins, (meth)acrylates, isocyanates, blocked isocyanates, polyacids, acid anhydrides, organometallic acid-functional materials, polyamines, polyamides, aziridines, and combinations thereof.

[0153] As a non-limiting example, the crosslinked material may include a melamine resin.

[0154] Any of these crosslinking agents known to those skilled in the art for use with curable acrylic polymers can be used. For the foregoing purposes, the crosslinking agent (when present) can be considered part of the film-forming resin material.

[0155] Other non-limiting examples of suitable classes of polymers that can be used as curable film-forming resins are:

[0156] (i) Polyepoxides and polyacid crosslinking agents;

[0157] (ii) (Meth)acrylic silane polymers, (meth)acrylic polyol polymers, and alkylated melamine-formaldehyde

[0158] crosslinking agents; and

[0159] (iii) Polyisocyanates and polymers having groups reactive with isocyanates.

[0160] Non-limiting examples of polyisocyanates include aliphatic and aromatic polyisocyanates and mixtures thereof. As specific non-limiting examples, higher polyisocyanates such as isocyanurates of diisocyanates can be used; diisocyanates, uretdiones, and biurets can also be used. Isocyanate prepolymers can also be used, non-limiting examples including reaction products of polyisocyanates with polyols. Mixtures of polyisocyanate crosslinking agents can be used.

[0161] As a non-limiting example, the polyisocyanate can be prepared from various isocyanate-containing materials. Non-limiting examples of suitable polyisocyanates include trimers prepared from the following diisocyanates: toluene diisocyanate, 4,4'-methylene-bis(cyclohexyl isocyanate), isophorone diisocyanate, an isomeric mixture of 2,2,4- and 2,4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, tetramethylxylylene diisocyanate and / or 4,4'-diphenylmethane diisocyanate. Additionally, blocked polyisocyanate prepolymers of various polyols (such as polyester polyols) can also be used.

[0162] If desired, the isocyanate groups can be blocked or unblocked. If 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 blocking agent for the polyisocyanate. Non-limiting examples of suitable blocking agents include those materials that deblock at elevated temperatures, such as aliphatic alcohols, including methanol, ethanol and n-butanol; cycloaliphatic alcohols, such as cyclohexanol; aromatic alkyl alcohols, such as benzyl alcohol and methylbenzyl alcohol; and phenolic compounds, such as phenol itself and substituted phenols, where the substituents do not affect the coating operation, such as cresol and nitrophenol. Glycol ethers can also be used as blocking agents. Non-limiting examples of suitable glycol ethers include ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, ethylene glycol monomethyl ether and propylene glycol monomethyl ether. Other non-limiting examples of suitable blocking agents include oximes, such as methyl ethyl ketoxime, acetone oxime and cyclohexanone oxime; lactams, such as ε-caprolactam; pyrazoles, such as dimethylpyrazole; and amines, such as dibutylamine.

[0163] The amount of film-forming resin in the coating composition generally includes any film-forming polymers and crosslinkers contained in the coating composition. Based on the total solids of the coating composition, the amount of film-forming resin in the coating composition can be at least 0.1 wt%, such as at least 0.5 wt%, at least 1 wt%, at least 5 wt%, at least 10 wt%, at least 15 wt% and at least 20 wt%, and can be up to 95 wt%, such as up to 93 wt%, up to 90 wt% and up to 87 wt% and can be from 0.1 wt% to 95 wt%, such as from 0.5 wt% to 95 wt%, from 1 wt% to 95 wt%, from 5 wt% to 95 wt%, from 10 wt% to 95 wt%, from 15 wt% to 95 wt%, from 20 wt% to 95 wt%, from 1 wt% to 90 wt%, from 5 wt% to 90 wt%, from 10 wt% to 90 wt%, from 15 wt% to 90 wt%, from 20 wt% to 90 wt%, from 1 wt% to 87 wt%, from 5 wt% to 87 wt%, from 10 wt% to 87 wt%, from 15 wt% to 87 wt% and from 20 wt% to 87 wt%. If the amount of film-forming resin is too low, the final coating may not have the desired properties, and if the amount of film-forming resin is too high, the coating composition may not have the desired rheological properties. The amount of film-forming resin in the coating composition can be any value or range between (and including the end values) any of the above values. The number average and weight average molecular weights of the film-forming resin are as described above.

[0164] As a non-limiting example, when included in the coating composition, the crosslinking material can be present at 1 wt% to 30 wt% of the total solids of the coating composition, such as 5 wt% to 30 wt% or 10 wt% to 30 wt%. The film-forming polymer or resin including at least one crosslinking functional group can be present at 1 wt% to 40 wt%, such as 5 wt% to 40 wt% or 10 wt% to 40 wt%.

[0165] The coating composition described herein can be a thermosetting composition.

[0166] The coating compositions described herein may include an adhesion promoter. Specific adhesion promoters may be selected for the desired properties of a particular substrate, non-limiting examples being metals or plastics. In non-limiting examples, the adhesion promoter includes free acids, which may include organic and / or inorganic acids included as separate components of the coating composition, rather than any acids that may be used to form polymers that may be present in the coating composition. Free acids may include tannic acid, gallic acid, phosphoric acid, phosphorous acid, citric acid, malonic acid, their derivatives, or mixtures thereof. Suitable derivatives include esters, amides, and / or metal complexes of such acids. Generally, the free acid includes phosphoric acid, such as 100 percent orthophosphoric acid, metaphosphoric acid, or aqueous solutions thereof, such as 70 to 90 percent phosphoric acid solutions. Other non-limiting examples of suitable adhesion promoting components include metal phosphates, organic phosphates, and organic phosphonates and metal phosphates, including zinc phosphate, iron phosphate, manganese phosphate, calcium phosphate, magnesium phosphate, cobalt phosphate, zinc-iron phosphate, zinc-manganese phosphate, zinc-calcium phosphate. Other non-limiting examples of adhesion promoters include phosphated epoxy resins, which may include the reaction product of an epoxy functional material and a phosphorus-containing material. Additional non-limiting examples of adhesion promoters include alkoxysilane adhesion promoters such as acryloxyalkoxysilanes, such as γ-acryloxypropyltrimethoxysilane and methacrylate-based alkoxysilanes, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2(aminoethyl)3-amino-propylmethyldimethoxysilane, N-2(aminoethyl)3-amino-propyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and siloxane borates.

[0167] The present disclosure provides a method of forming a coating layer on at least a portion of a substrate, the method comprising applying any one of the coating compositions described herein to the substrate using a high transfer efficiency applicator.

[0168] As a non-limiting example, the high transfer efficiency applicator includes nozzle orifices that discharge the coating composition in the form of droplets or jets from the nozzle orifices.

[0169] A high transfer efficiency applicator may include a plurality of nozzles, and each nozzle is capable of discharging a coating composition to form a jet stream in the form of a line segment, a planar jet stream or a thin layer, a hollow cylindrical jet stream, or wherein the nozzles discharge the coating composition cooperatively to form a liquid film.

[0170] The present disclosure also relates to methods of forming a coating layer on at least a portion of a substrate. These methods include, but are not limited to, flowing any one of the coating compositions described herein through one or more applicators, the one or more applicators including one or more nozzles capable of applying shear stress to the coating composition. When the coating composition is exposed to high shear stress in the nozzle, its viscosity decreases as described herein when flowing through the nozzle. The coating composition may form a continuous stream or discrete droplets when exiting the nozzle. When the coating composition contacts the substrate, it forms a uniform coating.

[0171] The coating composition may be applied to a substrate positioned substantially horizontally relative to the ground. As used herein, a substrate positioned "substantially horizontally relative to the ground" means that at least a portion of the surface to be coated is parallel to the ground or within 10°, such as within 5°, of being parallel to the ground.

[0172] The coating composition may be applied to a substrate positioned substantially vertically relative to the ground. As used herein, a substrate positioned "substantially vertically relative to the ground" means that at least a portion of the surface to be coated is perpendicular to the ground or within 45°, such as within 40°, within 30°, within 20°, within 10°, or within 5°, of being perpendicular to the ground.

[0173] The coating composition may have a surface tension such that the difference (surface energy of the substrate - surface tension of the coating composition) between the surface energy of the substrate and the surface tension of the coating composition of the uncoated or coated coating layer may be greater than 0, such as greater than 0.5 mN / m, greater than 0.7 mN / m, greater than 1 mN / m, and greater than 2 mN / m, as determined according to DIN EN 14370:2004-11 (Surface active agents - Determination of surface tension; German version DIN EN 14370; 2004-11), and the surface tension of the substrate surface may be determined according to DIN EN ISO 19403-2:2020-04 (Wettability - Part 2; Determination of the surface free energy of solid surfaces by measurement of the contact angle). Without being bound by a particular theory, the difference in surface tension is considered to contribute at least in part to the suitability of the coating composition for application by precision application devices that can apply the coating composition without overspray.

[0174] The coating composition can be applied to at least a part of a substrate, whether the substrate is uncoated or at least partially coated with a coating layer, to form a coating layer. Non-limiting examples include primer coatings, base coats, clear coats, and top coats. Additionally, any of the coating compositions can be one-component (1-K), two-component (2-K), or multi-component coating compositions.

[0175] As a non-limiting example, the method according to the present disclosure includes applying a primer layer on the substrate before applying the coating composition. As a further non-limiting example, multiple coating layers can be applied to the substrate before applying the coating composition of the present disclosure. As non-limiting examples, the multiple coating layers can be selected from primer layers, base coats, top coats, and clear coats.

[0176] The substrates to which the coating composition can be applied include a variety of substrates. As non-limiting examples, the coating composition can be applied to transportation substrates, industrial substrates, aerospace substrates, etc. As a non-limiting example, the substrate can be a transportation vehicle or a part thereof.

[0177] As a non-limiting example, the substrate can include polymers or composites, such as fiberglass composites. Transportation vehicle parts typically made of thermoplastic and thermosetting materials include bumpers and trim pieces.

[0178] Non-limiting examples of substrates to which the coating composition can be applied include rigid metal substrates, such as ferrous metals, aluminum, aluminum alloys, copper, and other metals, as well as alloy substrates. Ferrous metal substrates can include iron, steel, and their alloys. Non-limiting examples of useful steel materials include cold-rolled steel, galvanized (zinc-coated) steel, electro-galvanized steel, stainless steel, pickled steel, zinc-iron alloys, and combinations thereof. Combinations or composites of ferrous and non-ferrous metals can also be used.

[0179] Non-limiting examples of steel substrates (such as cold-rolled steel or any of the steel substrates listed above) include those coated with a weldable, zinc-rich, or iron phosphate-rich organic coating. Cold-rolled steel can also be suitable when pretreated with a suitable solution known in the art, such as a metal phosphate solution, an aqueous solution containing a Group IIIB or IVB metal, an organic phosphate solution, an organic phosphonate solution, and combinations thereof, as described below. Non-limiting examples of aluminum alloys include those alloys used in the automotive or aerospace industries, such as the 2000, 6000, or 7000 series aluminum; specific examples are 2024, 7075, and 6061. The alloys can be unclad, or they can include a cladding layer on the surface, which is composed of an aluminum alloy different from the base / bulk alloy below the cladding layer.

[0180] Non-limiting examples of the substrate include more than one metal or metal alloy, where the substrate can be a combination of two or more metal substrates assembled together, such as hot-dip galvanized steel assembled with an aluminum substrate.

[0181] Non-limiting examples of the shape of the metal substrate include being in the form of a sheet, plate, rod, bar, or any desired shape, but in many cases it can be in the form of an automotive component, such as a body, door, trunk lid, fender, hood, or bumper. The thickness of the substrate can vary as needed.

[0182] When there is no intermediate coating between the substrate and the coating composition, the coating can be applied directly to the metal substrate. This means that the substrate can be bare (as described below), or it can be treated with a pretreatment composition (as described below), but before applying the curable film-forming composition described herein, the substrate is not coated with any coating composition (such as an electrodepositable composition or a primer composition).

[0183] As described above, the substrate to be used can be a bare metal substrate, in other words, the original metal substrate that has not been treated with any pretreatment composition (such as a conventional phosphating bath, heavy metal pickling solution, etc.). Additionally, the bare metal substrate that can be used herein can be the cut edge of a substrate that has been otherwise treated and / or coated on the rest of its surface. Alternatively, before applying the coating composition, the substrate can undergo processing steps known in the art.

[0184] Conventional cleaning procedures and materials can be used to clean the substrate. Non-limiting examples include weakly alkaline or strongly alkaline cleaners, such as commercially available cleaners that are routinely used in metal pretreatment processes. Such cleaners are usually followed and / or preceded by a water rinse. The metal surface can also be rinsed with an acidic aqueous solution after cleaning with an alkaline cleaner or instead of cleaning with an alkaline cleaner. Non-limiting examples of the rinse solution include weakly acidic or strongly acidic cleaners, such as a dilute nitric acid solution that is commercially available and routinely used in metal pretreatment processes.

[0185] According to the compositions, methods, systems, and substrates of the present disclosure, at least a portion of the surface of a cleaned aluminum substrate can be mechanically or chemically deoxidized, in other words, the oxide layer found on the surface of the substrate can be removed in order to facilitate the uniform deposition of a pretreatment composition (described below) and to promote the adhesion of the pretreatment composition coating to the substrate surface. Non-limiting examples of suitable deoxidizers include mechanical deoxidizers that can uniformly roughen the substrate surface, such as by using a scrubbing or cleaning pad, and chemical deoxidizers, non-limiting examples of which include nitric acid, fluoboric acid, sulfuric acid, chromic acid, hydrofluoric acid, and ammonium bifluoride, or Amchem 7 / 17 deoxidizer (available from Henkel Technologies, Madison Heights, Mich.), OAKITE DEOXIDIZER LNC (commercially available from Chemetall), TURCO DEOXIDIZER 6 (commercially available from Henkel), or combinations thereof. Generally, chemical deoxidizers include a carrier, typically an aqueous medium, such that the deoxidizer can be in the form of a solution or dispersion in the carrier, in which case the solution or dispersion can be contacted with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, intermittent spraying, post-dipping spraying, post-spraying dipping, brushing, or roll coating.

[0186] According to the method of the present disclosure, the coating composition can be a colored coating composition, such as a colored primer coating composition. The method can further include applying a primer layer or a colored primer to the substrate using a high transfer efficiency applicator, and then applying the colored primer coating composition to at least a portion of the substrate. The method can further include forming a clear coat by applying a clear coat coating composition to at least a portion of the primer coat using a high transfer efficiency applicator. For the avoidance of doubt, in the disclosed method, any layer can be conventionally applied, provided that at least one of the plurality of coating layers is applied using a high transfer efficiency applicator.

[0187] The coating compositions of the present disclosure may include pigments and / or dyes as colorants. As non-limiting examples, the coating compositions in the present disclosure may be colored primer coating compositions. Non-limiting examples of suitable pigments include organic and / or inorganic materials, untreated aluminum, treated aluminum (with silica, inorganic pigments, and / or organic pigments), titanium dioxide, zinc oxide, iron oxide, carbon black, carbazole dioxazine crude pigments, azo, monoazo, bisazo, naphthol AS, lakes, benzimidazolone, metal complexes, isoindolinone, isoindoline, and polycyclic phthalocyanines, quinacridone, perylene, perinone, diketopyrrolopyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylium, quinophthalone pigments, diketopyrrolopyrrole red (“DPPBO red”), monoazo red, red iron oxide, quinacridone maroon, transparent red oxide, cobalt blue, iron blue, iron oxide yellow, chromium titanate, titanium yellow, nickel titanate yellow, reduced and / or composite tungsten oxide, transparent yellow oxide, lead chromate yellow, bismuth vanadate yellow, pre-dulled chrome yellow, transparent red oxide wafers, iron oxide red, molybdate orange, molybdate orange red, radar reflective pigments, LiDAR reflective pigments, anti-corrosion pigments, and combinations thereof.

[0188] Non-limiting examples of suitable dyes include solvent- and / or water-based dyes such as photochromic dyes, acid dyes, azo dyes, basic dyes, direct dyes, disperse dyes, reactive dyes, solvent dyes, sulfur dyes, mordant dyes (non-limiting examples include bismuth vanadate, anthraquinone, perylene, aluminum, quinacridone, thiazole, thiazine, azo, indigo, nitro, nitroso, oxazine, phthalocyanine, quinoline, stilbene, and triphenylmethane), dioxazine carbazole violet, phthalocyanine blue, indanthrone blue, monoazo permanent orange, iron yellow, benzidine yellow, indolinone yellow, monoazo yellow, benzimidazolone yellow, isoindoline yellow, tetrachloroisoindoline yellow, bisazo yellow, anthrone orange, quinacridone orange, benzimidazolone orange, phthalocyanine green, quinacridone red, azo red, diketopyrrolopyrrole red, perylene red, scarlet or maroon, quinacridone violet, thioindigo red, and combinations thereof.

[0189] When the coating compositions of the present disclosure contain dyes, by way of non-limiting example, the dyes can include photosensitive compositions and / or photochromic compositions that reversibly change their color upon exposure to one or more light sources. The photosensitive compositions and / or photochromic compositions can be used in the coating compositions of the present disclosure or in multiple layers of the multilayer composite materials described herein. The photochromic and / or photosensitive compositions can be activated by exposure to radiation of a specific wavelength. By way of non-limiting example, when the photochromic and / or photosensitive compositions become excited, the molecular structure changes and the altered structure exhibits a new color different from the original color of the composition. When the exposure to radiation is removed, the photochromic and / or photosensitive compositions can return to a resting state, wherein the original color of the composition is restored. By way of non-limiting example, the photochromic and / or photosensitive compositions may be colorless in the non-excited state and exhibit a color in the excited state. The complete color change can occur within milliseconds to several minutes (such as 0.01 second to 120 seconds or 20 seconds to 60 seconds). Non-limiting examples of the photochromic and / or photosensitive compositions include photochromic dyes.

[0190] By way of non-limiting example of the photosensitive compositions and / or photochromic compositions used in the coating compositions of the present disclosure, the photosensitive compositions and / or photochromic compositions can be associated with and / or at least partially bonded (such as by covalent bonding) to a polymer material of a polymerizable ethylenically unsaturated monomer and / or a polymerizable component. Different from some coatings in which the photosensitive composition can migrate out of the coating and crystallize into the substrate, the migration of the photosensitive composition and / or photochromic composition associated with and / or at least partially combined with the polymer and / or polymerizable component according to the present disclosure outside the coating is minimal. Exemplary photosensitive compositions and / or photochromic compositions and methods for their preparation are described in U.S. Patent No. 8,153,344, columns 9, line 7 to column 11, line 7 and column 11, line 23 to column 15, line 5, the specific portions of which are incorporated herein by reference.

[0191] The coating composition can contain radar reflective pigments or LiDAR reflective pigments or infrared reflective pigments. The LiDAR, radar reflective pigments or infrared reflective pigments can include, but are not limited to, nickel manganese ferrite black (Pigment Black 30), chromite iron brown black (CI Pigment Green 17, CI Pigment Brown 29 and 35), Pigment Blue 28, Pigment Blue 36, Pigment Green 26, Pigment Green 50, Pigment Brown 33, Pigment Brown 24, Pigment Black 12 and Pigment Yellow 53 and combinations thereof.

[0192] As a non-limiting example, a LiDAR reflective pigment can comprise a semiconductor and / or dielectric (“SCD”) in which a metal can be dispersed. The medium in which the metal can be dispersed (e.g., the SCD) can also be referred to herein as a matrix. The metal and the matrix can form a heterogeneous mixture that can be used to form a pigment. The metal can be dispersed uniformly or non-uniformly throughout the matrix. As a non-limiting example, the semiconductor of the LiDAR reflective pigment can include silicon, germanium, silicon carbide, boron nitride, aluminum nitride, gallium nitride, silicon nitride, gallium arsenide, indium phosphide, indium nitride, indium arsenide, indium antimonide, zinc oxide, zinc sulfide, zinc telluride, tin sulfide, bismuth sulfide, nickel oxide, boron phosphide, titanium dioxide, barium titanate, iron oxide, its doped form (i.e., adding dopants such as, for example, boron, aluminum, gallium, indium, phosphorus, arsenic, antimony, germanium, nitrogen, at a weight percentage of 0.01% or less based on the weight of the LiDAR reflective pigment), its alloy form, other semiconductors, or combinations thereof. As a non-limiting example, the LiDAR reflective pigment can include silicon. The dielectric of the LiDAR reflective pigment can comprise a solid insulating material (e.g., silica), ceramics (e.g., alumina, yttrium oxide, yttrium aluminum garnet (YAG), neodymium-doped YAG (Nd:YAG)), glass (e.g., borosilicate glass, soda-lime silicate glass, phosphate glass), organic materials, its doped form, other dielectrics, or combinations thereof. The organic materials can include, for example, acrylic, alkyd, chlorinated polyether, diallyl phthalate, epoxy resin, epoxy polyamide, phenolic, polyamide, polyimide, polyester (e.g., PET), polyethylene, polymethyl methacrylate, polystyrene, polyurethane, polyvinyl butyral, polyvinyl chloride (PVC), copolymers of PVC and vinyl, acetate, polyvinyl formal, polyvinylidene fluoride, polyphenylene dimethyl, silicone, nylon and copolymers of nylon, polyamide-polyimide, polyolefin, polytetrafluoroethylene, other polymers, or combinations thereof. If the dielectric includes organic materials, the organic materials are selected such that the resulting pigment is resistant to melting and / or changes in size or physical properties when incorporated into coatings, films, and / or article formulations. For example, the metal in the LiDAR reflective pigment can include, for example, aluminum, silver, copper, indium, tin, nickel, titanium, gold, iron, its alloys, or combinations thereof. The metal can be in particulate form and can have an average particle size range of from 0.5 nm to 100 nm, such as from 1 nm to 10 nm, as measured by transmission electron microscopy (TEM) at 100 kV. The metal can be in microparticulate form and can have an average particle size of less than or equal to 20 nm, as measured by TEM. Suitable methods for measuring particle size by TEM include suspending the metal particles in a solvent, then drop-casting the suspension onto a TEM grid and allowing it to dry under ambient conditions.The particle size measurement results can be obtained from images acquired using a Tecnai T20 TEM operating at 200 kV and analyzed using ImageJ software or equivalent instruments and software.

[0193] As a non-limiting example, the coating composition may include corrosion-inhibiting pigments. Any suitable corrosion-inhibiting pigments known in the art can be used in the coating composition. Non-limiting examples include Calcium Strontium Zinc Phosphosilicate; double orthophosphates, where one of the cations is represented by zinc, non-limiting examples being Zn-Al, Zn-Ca, Zn-K, Zn-Fe, Zn-Ca-Sr, Ba-Ca, Sr-Ca, and combinations thereof; combinations of phosphate anions with anions having good anti-corrosion effects, non-limiting examples being silicate, molybdate, and borate; modified phosphate pigments modified with organic corrosion inhibitors and combinations thereof. Non-limiting examples of modified phosphate pigments include aluminum(III) zinc(II) phosphate, basic zinc phosphate, zinc phosphomolybdate, zinc calcium phosphomolybdate, zinc borophosphate, zinc strontium phosphosilicate, calcium barium phosphosilicate, calcium strontium zinc phosphosilicate, and combinations thereof. Other non-limiting examples of corrosion-inhibiting pigments that can be used in coating formulations include zinc 5-nitroisophthalate, calcium 5-nitroisophthalate, calcium cyanurate, metal salts of dinonylnaphthalenesulfonic acid, and combinations thereof.

[0194] When the colorant is included in the coating composition, it can be included at levels of at least 0.1 wt%, such as at least 0.15 wt%, at least 0.2 wt%, at least 0.5 wt%, and at least 1 wt%, based on the weight of the coating composition, and can be included up to 40 wt%, such as up to 37 wt% and up to 34 wt%. Additionally, based on the weight of the coating composition, the amount of the colorant can be from 0.5 wt% to 40 wt%, such as from 0.15 wt% to 38 wt% and from 1 wt% to 34 wt%. When the amount of the colorant is too low, the desired color effect from the coating may not be achieved. When the amount of the colorant is too high, it may have an adverse effect on the rheological properties of the coating composition. When the colorant is included in the coating composition, it can be included at any level or range between (and including the end values) any of the above levels.

[0195] As non-limiting examples, coating composition can include various other components, such as adhesive, carrier, water, catalyst, conventional additives or their combination. Conventional additives can include but are not limited to dispersants, antioxidants and absorbents, wetting agents, leveling agents, defoamers, anti-cratering agents, thermoplastic resins, plasticizers, wear-resistant particles, fillers (including but not limited to mica, talcum, clay and inorganic minerals), metal oxides, metal flakes, various forms of carbon, antioxidants, hindered amine light stabilizers, UV light absorbers and stabilizers, surfactants, flow and surface control agents, thixotropic agents, reactive diluents, catalysts, reaction inhibitors, corrosion inhibitors, other conventional auxiliary agents and combinations thereof. Coating composition can be applicable to be applied to substrates.

[0196] As a non-limiting example, when metallic flake pigments are used, they may have an aspect ratio of 5:1 to 500:1, such as 10:1 to 200:1.

[0197] The coating composition of the present disclosure can be applied by any means, such as spraying, electrostatic spraying, dipping, rolling brushing, dipping, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, rolling, etc. The coating composition can also be applied with a precision coating device that can apply the coating composition without any overspray. Therefore, such devices can apply the coating composition on a substrate that is not shielded by a removable material (such as, for example, a tape material). The characteristics of the coating composition described herein used in combination with the precision coating device can enable the coating composition to be applied on at least a portion of the substrate without overspraying.

[0198] The method according to the present disclosure includes applying the coating composition described herein using a high transfer efficiency applicator. As a non-limiting example, the clear coat coating composition can be applied to at least a portion of the coating composition applied to the substrate. One or both of the coating compositions can be applied using a high transfer efficiency applicator.

[0199] Applicators that apply the coating composition without overspray can be used to create desired patterns and / or designs on the substrate. As a non-limiting example, these applicators can apply the coating composition in one go without masking the substrate, thereby creating two or more colors on different portions of the substrate.

[0200] Non-limiting examples of devices that can apply the coating composition without overspray include devices that apply the composition as a continuous jet, as continuous droplets, and / or as droplets on demand. Specific non-limiting examples of such devices include piezoelectrically actuated valve injectors, air-actuated valve injectors, continuous inkjet printers, gas jet droplet generators, vibrating tip droplet generators, piezoelectrically actuated micro-pneumatic droplet generators, and electrohydrodynamic droplet generators.

[0201] The applicator can be a high transfer efficiency applicator, which includes a nozzle with an opening. The high transfer efficiency applicator can include more than one or multiple nozzles. The nozzle opening can have any suitable shape, non-limiting examples being circular, oval, square, and rectangular. The nozzle can include a channel having the same cross-sectional shape and dimensions as the opening. The diameter of the nozzle opening can be at least 20 μm, such as at least 25 μm, at least 50 μm, and at least 75 μm, and can be up to 400 μm, such as up to 300 μm, up to 275 μm, up to 250 μm, up to 225 μm, and up to 200 μm and can be from 20 μm to 400 μm, such as from 25 μm to 300 μm, from 25 μm to 250 μm, from 25 μm to 200 μm, from 50 μm to 300 μm, from 50 μm to 250 μm, from 50 μm to 200 μm, from 75 μm to 300 μm, from 75 μm to 250 μm, and from 75 μm to 200 μm. The nozzle opening can be any value or range between (and including) any of the values recited above. The droplets or streams emitted from the nozzle can have the same diameter as the nozzle opening.

[0202] As a non-limiting example, the high transfer efficiency applicator can include one or more nozzles having nozzle orifices with diameters in the range of 20 μm to 400 μm, such as 25 μm to 350 μm or 35 μm to 300 μm, and further wherein the droplets or jets discharged from the orifices each have diameters in the range of 20 μm to 400 μm, such as 25 μm to 350 μm or 35 μm to 300 μm.

[0203] The droplet diameter can be determined using a JetXpert droplet viewer, and its analysis function is now operating in a dual-pulse mode and can be obtained from ImageXpert, Inc. Similarly, the nozzle diameter can be determined using the nozzle checker function of JetXpert.

[0204] The coating composition can be supplied to the applicator under pressure (e.g., greater than 1 atmosphere). In many cases, multiple nozzles each include a cylindrical channel having the same diameter as the nozzle opening. The combination of pressure and channel size results in shear stress being applied to the coating composition. The shear thinning property of the coating composition as described above allows the coating composition to be discharged from the nozzle at a desired flow rate or droplet rate.

[0205] The flow rate of the fluid or the droplet rate can be at least 25 cc / min, such as at least 50 cc / min and at least 75 cc / min, and can be up to 300 cc / min, such as up to 275 cc / min, up to 250 cc / min, up to 225 cc / min and up to 200 cc / min and can be from 25 cc / min to 300 cc / min, such as from 50 cc / min to 300 cc / min, from 75 cc / min to 300 cc / min, from 25 cc / min to 250 cc / min, from 50 cc / min to 250 cc / min, from 75 cc / min to 250 cc / min, from 25 cc / min to 200 cc / min, from 50 cc / min to 200 cc / min and from 75 cc / min to 200 cc / min. When the flow rate or the droplet rate is too low, the coating layer may not have the desired properties. If the flow rate or the droplet rate is too high, the coating may be prone to puddling and / or sagging. The flow rate or the droplet rate can be any value or range between (and including) any of the values described above.

[0206] When applied according to the methods and systems described herein, the coating compositions described herein have a high transfer efficiency. In other words, most (if not all) of the coating composition is applied to the substrate after leaving the applicator and there is no waste and / or overspray. The transfer efficiency of the coating composition can be at least 90 wt%, such as at least 91 wt%, at least 92 wt% and at least 93 wt%, and can be up to 100 wt%, such as up to 99 wt% and up to 98 wt% and can be from 90% to 100%, such as from 92% to 100% and from 93% to 99%. The transfer efficiency of the coating composition can be any value or range between (and including the end values) of any of the above values.

[0207] The transfer efficiency can be increased by positioning the applicator close to the substrate. Thus, the distance from the tip of the nozzle in the applicator to the substrate can be at least 0.5 cm, such as at least 0.6 cm and at least 0.75 cm, and can be up to 5 cm, up to 4 cm and up to 3 cm, and can be from 0.5 cm to 5 cm, such as from 0.5 cm to 4 cm, 0.5 to 3 cm, from 0.75 cm to 5 cm, from 0.75 cm to 4 cm and from 0.75 to 3 cm. The distance from the applicator to the substrate can be any value or range between (and including) any of the values described above.

[0208] The high transfer efficiency of the coating composition and the close proximity of the applicator to the substrate can minimize the evaporation of volatile components when the coating composition is applied to the substrate. The total solids of the applied coating composition can be within at least 10 wt% of the total solids of the coating composition entering the applicator, such as within at least 7.5 wt% and at least 5 wt% and can be within 1 wt%, such as within 2 wt% and within 3 wt%. Generally, the volatile components are not lost, and the composition of the applied coating composition is the same as the coating composition entering the applicator. The total solids of the applied coating composition can be any value or range between (and including) any of the above values compared to the total solids of the coating composition entering the applicator.

[0209] As described above, an applicator suitable for the methods and systems described herein and for use with a coating composition can include a plurality of nozzles. The number of nozzles on the applicator can be at least one, such as at least 5 and at least 10, and can be up to 3,000, such as up to 2,700, up to 2,250, up to 2,000, up to 1,500, up to 1,000, up to 500, up to 100, up to 75, up to 70 and up to 65 and can be 5 to 1,000, such as 10 to 500 and 10 to 100. The number of nozzles included in the applicator can be any value or range between (and including) any of the values recited above.

[0210] Depending on the number of nozzles included on the applicator, the path width of the applicator can be at least 0.5 cm, such as at least 1 cm, at least 2.5 cm and at least 5 cm, and can be up to 15 cm, such as up to 14 cm, up to 13 cm and up to 12 cm and can be 1 cm to 15 cm, such as 2.5 cm to 14 cm and 5 to 15 cm. The path width of the coating composition can be any value or range between (and including) any of the above values.

[0211] Due to the high transfer efficiency, the rheological properties of the coating composition, and the use of the efficient applicator as described herein, there is little or no overlap between passes of the applicator within the target area or target deposition path.

[0212] Due to the high transfer efficiency, the rheological properties of the coating composition, and the use of the efficient applicator as described herein, the applicator can move relatively quickly across the substrate in the target area or along the target deposition path. Accordingly, the applicator can have a tip speed of at least 50 mm / sec, such as at least 100 mm / sec and at least 200 mm / sec and can be up to 1000 mm / sec, such as up to 750 mm / sec and up to 500 mm / sec and can be from 50 mm / sec to 1000 mm / sec, such as from 50 mm / sec to 750 mm / sec, from 50 mm / sec to 500 mm / sec, from 100 mm / sec to 1000 mm / sec, from 100 mm / sec to 750 mm / sec, from 100 mm / sec to 500 mm / sec, from 200 mm / sec to 1000 mm / sec, from 200 mm / sec to 750 mm / sec, and from 200 mm / sec to 500 mm / sec. The tip speed of the applicator can be any value or range between (and including) any of the values recited above.

[0213] The coating composition can be applied directly to the substrate to provide a primer coating. Additionally, the coating composition can be applied as a base coat, and the base coat can include a colorant. Further, the coating composition can be a clear coat that can cover at least a portion of any of the coatings described herein. The coating composition described herein can be a final coat or a top coat that covers at least a portion of the coatings described herein.

[0214] The present disclosure will be further described with reference to the following non-limiting examples.

[0215] Examples

[0216] Example 1 (High acid shell)

[0217] An acrylic latex was prepared as follows: A mixture of 1268 g of deionized water and 4.4 g of an alcohol ethoxylate surfactant (Rhodapex AB / 20, available from Solvay Société anonyme) was charged into a four-necked flask and heated to 65 °C under a nitrogen blanket.

[0218] A mixture of 6.4 g of butyl acrylate, 19 g of methyl methacrylate, and 0.6 g of methacrylic acid was added to the flask and heated to 85 °C. A solution of 0.21 g of ammonium persulfate in 33 g of deionized water was added, and the resulting mixture was held at 85 °C for 30 minutes.

[0219] A pre-emulsion of 753 g of deionized water, 9.7 g of Rhodapex AB / 20, 473 g of methyl methacrylate, 190 g of butyl acrylate, 41.4 g of 50% acrylamide solution, 17.5 g of ethylene glycol dimethacrylate and 17.4 g of hydroxyethyl methacrylate was added to a flask over 3 hours, while adding a solution of 0.58 g of ammonium persulfate and 151 g of deionized water. The resulting mixture was held at 85 °C for one hour.

[0220] A pre-emulsion of 95 g of deionized water, 1.4 g of Rhodapex AB / 20, 39.5 g of butyl acrylate, 49.3 g of methacrylic acid, 18.1 g of methyl methacrylate and 26.2 g of hydroxyethyl acrylate was added to a flask over 1.5 hours, while adding a solution of 0.3 g of ammonium persulfate, 0.95 g of granular borax and 116 g of deionized water, and then held at 85 °C for two hours.

[0221] The resulting mixture was cooled to 70 °C, and a solution of 6.3 g of dimethylethanolamine in 39 g of deionized water was added to the flask over 20 minutes. 8.9 g of the fungicide Acticide (MBS) (obtainable from THOR AMERICAS, Inc.) was dissolved in 31 g of deionized water, added to the flask, followed by 15.9 g of deionized water. The resulting latex was then cooled to 23 °C.

[0222] The viscosity of the resulting latex was determined using a Brookfield viscometer obtainable from AMETEK, Inc., to be 1764 cp at 20 rpm and 23 °C using rotor #2, and the particle size was determined to be 153.2 nm (Z-average, determined using a Zetasizer dynamic light scattering instrument obtainable from MalvernPanalytical Ltd). The final total solids were determined to be 25.4 wt% after placing the sample at 110 °C for one hour and dividing the final weight by the initial sample weight. The particle size was measured by dynamic light scattering using a Malvern Zetasizer, a high-performance dual-angle particle size analyzer for enhanced detection of aggregates and measurement of small or dilute samples, and for measuring very low or very high concentration samples using dynamic light scattering.

[0223] Example 2 (Comparative)

[0224] An acrylic latex was prepared as follows: A mixture of 1268 g of deionized water and 4.4 g of an alcohol ethoxylate surfactant (Rhodapex AB / 20, obtainable from Solvay Société anonyme) was charged to a four-necked flask and heated to 65 °C under a nitrogen blanket.

[0225] A mixture of 6.4 g of butyl acrylate, 19 g of methyl methacrylate and 0.6 g of methacrylic acid was added to a flask and heated to 85 °C. A solution of 0.21 g of ammonium persulfate in 33 g of deionized water was added, and the resulting mixture was maintained at 85 °C for 30 minutes.

[0226] A pre-emulsion of 753 g of deionized water, 9.7 g of Rhodapex AB / 20, 473 g of methyl methacrylate, 190 g of butyl acrylate, 41.4 g of 50% acrylamide solution, 17.5 g of ethylene glycol dimethacrylate and 17.4 g of hydroxyethyl methacrylate was added to a flask over 3 hours, while adding a solution of 0.58 g of ammonium persulfate and 151 g of deionized water. The resulting mixture was maintained at 85 °C for one hour.

[0227] A pre-emulsion of 95 g of deionized water, 1.4 g of Rhodapex AB / 20, 39.5 g of butyl acrylate, 24.7 g of methacrylic acid, 18.1 g of methyl methacrylate and 26.2 g of hydroxyethyl acrylate was added to a flask over 1.5 hours, while adding a solution of 0.3 g of ammonium persulfate, 0.95 g of granular borax and 116 g of deionized water, and then maintained at 85 °C for two hours.

[0228] The resulting mixture was cooled to 70 °C, and a solution of 6.3 g of dimethylethanolamine in 39 g of deionized water was added to the flask over 20 minutes. 8.9 g of the fungicide Acticide (MBS) (available from THOR AMERICAS, Inc.) was dissolved in 31 g of deionized water, added to the flask, followed by 15.9 g of deionized water. The resulting latex was then cooled to 23 °C.

[0229] The viscosity of the resulting latex was determined using a Brookfield viscometer available from AMETEK, Inc., to be 43.6 cp at 100 rpm and 23 °C using rotor #2, and the particle size was determined to be 151.9 nm (Z-average, determined using a Zetasizer dynamic light scattering instrument available from MalvernPanalytical Ltd). The sample was placed at 100 °C for one hour and the final total solids were determined to be 24.7 wt% after dividing the final weight by the initial sample weight.

[0230] Examples 3 to 10

[0231] An aqueous thermosetting primer coat is prepared by weighing the amounts in Table 1 into a stirring container. Water is added to the designed amount, and dimethylethanolamine (DMEA, 50 wt% aqueous solution) is slowly added with stirring while measuring the pH value of the mixture until it reaches the range of 8.5 to 8.7. The remaining components of the formulation are added with stirring to avoid foaming. The sample is retested for 24 hours and readjusted with DMEA, stirring until the pH value of the mixture remains within the range of 8.5 to 8.7.

[0232] The shear flow viscosity of the sample is measured using an Anton Paar, MCR301 rheometer, which uses a Bob concentric cylinder device (CC27, gap size 1.13 mm), where the viscosity is measured in centipoise (cp) from 0.1 second -1 to 1000 seconds -1 inside. The sample is applied to an electrocoating primer steel sheet through an EcoPaintJet precision applicator, nozzle plate: M09150011 (Dürr Systems AG) to achieve the target film thickness for appearance and sag evaluation (Examples 3 to 10). Examples 5 to 9 were also evaluated at a lower film thickness. The plates are flash-dried at 25 °C for 4 minutes, then heat flash-dried at 70 °C for 7 minutes, and finally baked at 140 °C for 20 minutes.

[0233] Table 1

[0234]

[0235] 1 A urethane-acrylic hybrid dispersion, Daotan vtw 6463 / 36WA available from Allnex GMBH

[0236] 2 Similar to Envirobase T409 Black WB Tint available from PPG

[0237] 3 Resimene HM-2608 available from INEOS Melamines GmbH

[0238] 4 An ethylene-vinyl acetate copolymer wax, Aquatix 8421 available from BYK-Chemie GmbH

[0239]

[0240]

[0241] Example 3 and Example 10 have the same composition, except that Example 3 contains the high acid core-shell resin (Example 1) and Example 10 contains the low acid core-shell resin (Example 2). Example 3 exhibits non-Newtonian flow behavior, with a much higher viscosity at low shear (0.1 s -1 ) than at high shear (1000 s -1 ), while Example 10 exhibits Newtonian flow behavior, with similar viscosities at high shear (1000 s -1 ) and low shear (0.1 s -1 ). When compared to Example 10, the rheology of Example 3 gives the coating improved appearance and resistance to vertical sagging.

[0242] Example 4 explored reducing the total solids of the coating by using a small amount of rheological modifier (Aquatix 8421), while Example 6 explored reducing the total solids of the coating by using a small amount of rheological modifier (Aquatix 8421) and adding more organic solvents. Both Example 4 and Example 6 have the desired rheological properties and provide good application properties, especially improved appearance and vertical sagging when compared to Example 10.

[0243] Example 5 explored using a low acid core-shell resin (Example 2) with a higher amount of rheological modifier (Aquatix 8421) to achieve the desired low shear viscosity. The application properties were improved when compared to Example 10.

[0244] Examples 7 and 8 explored lower amounts of the high acid core-shell resin, replacing the Example 1 resin with a commercially available core-shell resin to make up for the difference in total solids. When compared to Example 10, the coating compositions of Examples 7 and 8 provided good application properties, especially improved appearance and vertical sagging.

[0245] Example 9 is a low solids version of Example 3 in many respects and provides good application properties, especially improved appearance and vertical sagging when compared to Example 10.

[0246] Examples 11 to 16

[0247] The core-shell resins of Examples 1 and 2 were evaluated at various concentrations at a pH of 8.5 - 8.7 at 25 °C and a pressure of 101.3 kPa (1 atm) on an Anton-Paar MCR301 rheometer equipped with a 50 mm cone-plate fixture to determine the minimum non-volatile content required for the solution to behave as a gel (G’ > G”). The G' and G” values were measured at ω = 1 rad / s and γ = 1% at each concentration. The gel transition was determined as weight % NV when G’ was greater than G”, or in other words, when the loss modulus tan(δ) (tan(δ) = G” / G’) was less than 1. The results are shown in Table 2.

[0248] Table 2

[0249] Example Core - shell resin Resin (wt%) G' (Pa) G” (Pa) Tan(δ) 11 Example 1 14 125.940 24.521 0.195 Gel 12 Example 1 12 52.642 10.795 0.205 Gel 13 Example 1 10 0.003 0.131 38.309 Liquid 14 Example 2 22 58.291 12.099 0.208 Gel 15 Example 2 20 25.507 7.793 0.306 Gel 16 Example 2 18 0.360 1.620 4.499 Liquid

[0250] The data shows that the core-shell resin of Example 1 undergoes a gel transition at less than 12 wt% NV, while the core-shell resin of Example 2 undergoes a gel transition at greater than 18 wt% NV (greater than 15 wt% NV).

[0251] Although specific embodiments of the present disclosure have been described above for purposes of illustration, it will be apparent to those skilled in the art that various modifications can be made to the details of the present disclosure without departing from the scope defined in the appended claims.

Claims

1. A coating composition, which comprises 6% to 15% by weight, such as 6% to 14% by weight or 7% to 13% by weight of total solids based on the weight of the coating composition; 15% to 70% by weight, such as 20% to 65% by weight or 25% to 60% by weight of core-shell resin particles based on the total solids; and A volatile organic compound (VOC) content of 50 g / L to 550 g / L, such as 100 g / L to 500 g / L or 150 g / L to 450 g / L; wherein the coating composition has a viscosity of from 30 mPa·s to 110 mPa·s, such as from 40 mPa·s to 100 mPa·s or from 45 mPa·s to 90 mPa·s at 1000 s -1 and has a viscosity of greater than 1000 mPa·s, such as greater than 2500 mPa·s or greater than 4000 mPa·s at 0.1 s -1 and the viscosity is measured using an Anton-Paar MCR301 rheometer equipped with a concentric cylinder fixture (CC27, gap size 1.13 mm) at 25 °C and a pressure of 101.3 kPa (1 atm); wherein the total solids and VOC are determined according to ASTM D2369 (2020) and ASTM D3960-05 respectively; and wherein the coating composition can be applied using a high transfer efficiency precision applicator.

2. The coating composition according to claim 1, wherein the core-shell resin particles comprise a viscoelastic gel, and the viscoelastic gel has a G' value greater than the G'' value measured at ω = 1 rad / s and γ = 1% at 25 °C and a pressure of 101.3 kPa (1 atm) using an Anton-Paar MCR301 rheometer equipped with a 50 mm cone-plate fixture when dispersed in an aqueous medium at a pH of greater than 0% to less than 14% by weight, such as 1% to 13% by weight, 2% to 13% by weight or 3% to 12% by weight.

3. The coating composition according to any one of claims 1 or 2, wherein the core-shell resin particles comprise a core obtained by polymerizing a monomer mixture, and the monomer mixture includes 0% to 99% by weight, such as 95% to 99% by weight or 96% to 99% by weight of a first non-ionic monomer conforming to the following formula: R 1 2 C = CR 1 -C(O)-W-R 6 where each R 1 is independently -H, -CH 3 or -CH 2 CH 3 ; W is selected from O, NR 4 and S; R 4 is H, CH 3 or CH 2 CH 3 ; and R 6 selected from C 1 to C 12 alkyl, C 5 to C 12 alicyclic group and C 6 to C 12 aromatic group or alkyl aromatic group, and optionally capable of including one or more -OH substitutions of hydrogen; 0% to 4% by weight, such as 1% to 4% by weight or 1% to 3% by weight of a carboxylic acid monomer conforming to the following formula: R 2 2 C = CR 2 -C(O)-OH where each R 2 is independently -H, -CH 3 or -CH 2 CH 3 ; and 0% to 100% by weight, such as 20% to 90% by weight or 20% to 80% by weight of a vinyl monomer conforming to the following formula: R 1 2 C=CR 1 -A-C(O)-R 9 where each R 1 is independently -H, -CH 3 or -CH 2 CH 3 ; A is NR 4 or O; R 4 is H, CH 3 or CH 2 CH 3 ; and R 9 is a straight-chain or branched alkyl group having 1 to 18 carbon atoms, or when A is nitrogen, R 9 is bonded to A to form a 5- to 7-membered ring; A shell obtained by polymerizing a monomer mixture, and the monomer mixture includes 0% to 40% by weight, such as 2% to 30% by weight or 5% to 20% by weight of a second non-ionic monomer conforming to the following formula: R 1 2 C=CR 1 -C(O)-Z-R 7 where each R 1 is independently -H, -CH 3 or -CH 2 CH 3 ; Z is selected from O, NR 4 , S and according to the formula -(O-CR 8 -CR 8 -) n -O- group where each R 8 is independently -H, -CH 3 or -CH 2 CH 3 ; and n is from 0 to 30, such as from 0 to 25 or from 1 to 25; R 7 selected from C 1 to C 18 alkyl, C 5 to C 12 alicyclic group and C 6 to C 18 aromatic group or alkylaromatic group, and optionally capable of including one or more -OH substitutions of hydrogen; R 4 is H, CH 3 or CH 2 CH 3 ; and 2% to 50% by weight, such as 20% to 50% by weight, 15% to 50% by weight or 15% to 40% by weight of a carboxylic acid monomer conforming to the following formula: R 2 2 C=CR 2 -C(O)-OH where each R 2 is independently -H, -CH 3 or -CH 2 CH 3 ; and 0% to 50% by weight, such as 0% to 40% by weight or 10% to 40% by weight of a vinyl monomer conforming to the following formula: R 1 2 C=CR 1 -A-C(O)-R 9 Each R 1 is independently -H, -CH 3 or -CH 2 CH 3 ; A is NR 4 or O; R 4 is H, CH 3 or CH 2 CH 3 ; and R 9 is a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, or when A is nitrogen, R 9 is bonded to A to form a 5- to 7-membered ring.

4. The coating composition according to claim 3, wherein after incorporating a monomer conforming to the following formula: R 1 2 C=CR 1 -A-C(O)-R 9 into either or both of the core or the shell of the core-shell resin particles, the incorporated residue hydrolyzes to leave a hydroxyl group (if A is oxygen) or an amine group (if A is nitrogen).

5. The coating composition according to any one of claims 1 to 4, which comprises an aqueous carrier.

6. The coating composition according to any one of claims 1 to 5, which comprises 60% to 93% by weight of water.

7. The coating composition according to any one of claims 1 to 6, which has a pH of 7.5 to 10, such as 7.6 to 9.

6.

8. The coating composition according to any one of claims 1 to 7, which comprises a rheology modifier.

9. The coating composition according to claim 8, wherein the rheology modifier comprises a rheology modifier selected from the group consisting of: inorganic thixotropic agents, acrylic alkali-swellable emulsions (ASEs), hydrophobically modified ethylene oxide urethane block copolymers (HEURs), hydrophobically modified alkali-swellable emulsions (HASEs), hydrophobically modified hydroxyethyl celluloses (HMHECs), copolymers of ethylene and vinyl acetate (EVA waxes), and mixtures thereof.

10. The coating composition according to any one of claims 8 or 9, wherein the amount of the rheology modifier in the coating composition is from 0% to 10% by weight, such as 1% to 9% by weight or 1% to 7.5% by weight, based on the total solids of the coating composition.

11. The coating composition according to any one of claims 1 to 10, which comprises a film-forming polymer or resin comprising at least one crosslinking functional group, and a crosslinking material comprising at least one functional group reactive with the crosslinking functional group.

12. The coating composition according to claim 11, which comprises from 1% to 30% by weight, such as 5% to 30% by weight or 10% to 30% by weight, of the crosslinking material based on the total solids of the coating composition.

13. The coating composition according to any one of claims 11 or 12, wherein the film-forming polymer or resin comprises a crosslinking functional group selected from the group consisting of hydroxyl groups, carboxyl groups, and amine groups.

14. The coating composition according to any one of claims 11 to 13, wherein the crosslinking material comprises a melamine resin.

15. A method of forming a coating layer on at least a portion of a substrate, the method comprising: applying a coating composition to the substrate using a high transfer efficiency applicator; wherein the coating composition comprises the coating composition according to any one of claims 1 to 14.

16. The method according to claim 15, wherein the high transfer efficiency applicator comprises a nozzle orifice that discharges the coating composition in the form of droplets or a jet stream.

17. The method according to any one of claims 15 or 16, wherein the high transfer efficiency applicator comprises a plurality of nozzles, and each nozzle discharges the coating composition to form a jet stream in the form of a line segment, a planar jet stream or a thin layer, a hollow cylindrical jet stream, or wherein the nozzles discharge the coating composition cooperatively to form a liquid film.

18. The method according to any one of claims 15 to 17, wherein the coating composition is a colored primer coating composition.

19. The method according to any one of claims 15 to 18, wherein the method comprises applying a primer layer on the substrate before applying the coating composition.

20. The method according to any one of claims 15 to 19, wherein a plurality of coating layers are applied to the substrate before applying the coating composition.

21. The method according to claim 20, wherein the plurality of coating layers are selected from a primer layer, a base coat layer, a top coat layer, and a clear coat layer.

22. The method according to any one of claims 15 to 21, which comprises applying a clear coat coating composition on at least a portion of the coating composition applied to the substrate using a high transfer efficiency applicator.

23. The method according to any one of claims 15 to 22, wherein the nozzle orifice has a diameter in the range of 20 μm to 400 μm, such as 25 μm to 350 μm or 35 μm to 300 μm, and further wherein each of the droplets or jets ejected from the orifice has a diameter in the range of 20 μm to 400 μm, such as 25 μm to 350 μm or 35 μm to 300 μm.

24. A substrate coated by the method according to any one of claims 15 to 23.

25. The substrate according to claim 24, wherein the substrate is a vehicle or a part thereof.

26. The coating composition, method, or substrate according to any of the preceding claims, wherein the coating composition comprises a photosensitive composition and / or a photochromic composition.

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