MX2008009258A - Decorative and durable coatings having a homogeneous hue, methods for their preparation, and articles coated therewith - Google Patents

Abstract

Disclosed are powder coating compositions suitable for producing a decorative and durable coating having a homogeneous hue, articles comprising a decorative and durable coating having a homogeneous hue deposited thereon, methods for preparing a decorative and durable coating having a homogeneous hue, kits capable of producing a decorative and durable coating having a homogeneous hue, and methods for color matching using powder coating compositions.

Description

DECORATIVE AND DURABLE COATINGS HAVING A HOMOGENEOUS TONE, THE METHODS FOR THEIR PREPARATION AND ARTICLES COATED WITH THEM FIELD OF THE INVENTION The present invention relates to powder coating compositions suitable for producing a decorative and durable coating having a homogeneous shade, to the articles in which said decorative and durable coating having a homogeneous shade is deposited, to methods for preparing said coating decorative and durable that has a homogeneous tone, and equipment capable of producing the decorative and durable coating that has a homogeneous tone. BACKGROUND OF THE INVENTION [0002] Frequently, powder coating compositions are required for use in various types of substrate coatings. Said coating compositions can greatly reduce or even eliminate the use of organic solvents which are often used in liquid coating compositions. When a powder coating composition is cured by heating, any volatile material is dispersed into the environment, if any. This is a significant advantage over liquid coating compositions in which the organic solvent is volatilized into the surrounding atmosphere when the coating composition is cured by heat. Powder coating compositions are typically produced by a complex process that includes the dry blending of various coating components such as, for example, color pigments, film-forming resins, curing agents and other additives as control agents. of flow and agents for the control of load, subjecting the resulting mixture to a heating, melting and kneading by the use of an extruder or similar element and then, subjecting the resulting extrudate to a cooling, grinding and classification (referred to herein as "process of extrusion "). In this way, the extrusion process requires many steps. A disadvantage of the use of powder coating compositions has been that, to obtain various coatings of different shades, the production of a separate powder coating composition for each desired shade has been required. When mixing the liquid coating compositions of different shades, it is possible to obtain a coating having a homogeneous shade that is different from the tone of each liquid coating composition mixed. On the other hand, when the typical powder coating compositions of different shades are dry mixed and the resulting mixture is applied to a substrate, the result is that, generally, each tone can be distinguished by visual inspection with the naked eye, producing the "salt and pepper" effect (mottled). In this way, it has been difficult if not impossible to achieve a coating of a desired shade from a dry mixture of two or more powder coating compositions of different shades. In this way, it would also be convenient to provide suitable powder coating compositions to produce a decorative and durable coating having a homogeneous shade, from a dry blend of two or more powder coating compositions, each of different hue. SUMMARY OF THE INVENTION In certain aspects, the present invention relates to powder coating compositions suitable for producing a decorative and durable coating. These coating compositions comprise a mixture of a first powder coating composition having a first shade and a second powder coating composition having a second shade different from the first. In addition, the first powder coating composition and / or the second powder coating composition comprise particles enclosed in a polymer that impart color. The powder coating compositions of the present invention, after being applied directly onAt least one portion of a substrate and being cured produce a decorative and durable coating that has a homogeneous tone different from the first and second tone. In another aspect, the present invention relates to articles in which the decorative and durable coating is deposited. The decorative and durable coating is deposited directly with a powder coating composition comprising a first powder coating composition having a first shade and a second powder coating composition having a second shade different from the first, wherein the first composition of powder coating and / or the second powder coating composition comprises particles enclosed in a polymer that impart color. In the articles of the present invention, the homogeneous tone is different from the first and the second. Even in other aspects, the present invention relates to methods for preparing decorative and durable coating having a homogeneous tone. These methods comprise: (a) providing a first powder coating composition having a first shade, (b) providing a second powder coating composition having a second shade different from the first, (c) mixing the first and second composition. powder coating, and (d) directly applying the mixture to at least a portion of a substrate. In these methods, the first and / or second powder coating composition comprises color imparting particles enclosed in a polymer. In still other aspects, the present invention relates to the equipment comprising: (a) a first container comprising a powder coating composition having a first shade and (b) a second container comprising a powder coating composition. that has a second tone different from the first. In the equipment of the present invention, the first and / or second container comprises a powder coating composition comprising particles enclosed in a polymer that impart color and, after mixing the contents of the first and second container, a composition of powder coating which, after directly applying on at least a portion of a substrate and curing, produces a decorative and durable coating having a homogeneous tone different from the first and second tone. The present invention also relates to methods for achieving a matching color using the powder coating compositions. These methods comprise: (a) providing a first powder coating composition having a first shade, (b) providing a second powder coating composition having a second shade different from the first, (c) mixing the first and second composition. powder coating in a proportion that produces the desired homogeneous shade when the mixture is applied directly on at least a portion of a substrate and cured. In these methods, the first and / or second powder coating composition comprises particles enclosed in a polymer that impart color. DETAILED DESCRIPTION OF THE INVENTION For the purpose of the following detailed description, it is to be understood that the invention may undergo several alternative variations and sequences of steps, except where expressly specified otherwise. Furthermore, when they do not refer to any of the operative examples or when indicated otherwise, all the numbers that express, for example, quantities of ingredients used in the specification and claims, must be modified, in all circumstances, by the finished "approximately". Thus, unless otherwise indicated, the numerical parameters determined in the following specification and appended claims are approximations that may vary depending on the desired properties to be obtained by the present invention. At a minimum, and without intending to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter must, at least, be considered in light of the number of significant digits reported and applying the ordinary rounding techniques. Although the ranges and numerical parameters determining the scope of the invention are approximations, the numerical values specified in the specific examples are reported as accurately as possible. Any numerical value, however, inherently contains certain errors that necessarily result from the standard variation found in their respective test measurements. In addition, it should be understood that any numerical range cited here, is intended to include all included sub-ranges. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the quoted minimum value of 1 and the maximum value of 10, that is, it has a minimum value equal to 1 or greater than 1 and a maximum value equal to or less than 10. In this application, the use of singular includes the plural and the plural includes the singular, unless specifically determined otherwise. In addition, in this application, the use of "or" means "and / or" unless otherwise specified, even if it is explicitly used "and / or" in certain cases. As mentioned previously, certain embodiments of the present invention relate to powder coating compositions to produce a decorative and durable coating. As used herein, "powder coating composition" refers to a composition suitable for producing a coating on a substrate, said coating being included in a particulate form, opposite to the liquid form. As used herein, the term "decorative and durable coating" refers to a coating that is both decorative, that is, provides the desired appearance to the substrate, as durable, that is, does not splinter, peel, spoil or delaminate when subject to environmental conditions, such as coatings used in components for cars and trucks, for example, bodywork, door panels, cabins, trailer bodies; components for airplanes, for example, fuselage and wings; components for architecture; electronic equipment, for example, computers and telephones, as well as other articles. That is, the "decorative and durable coatings" of the present invention are different from the decorative coatings formed from the use of dyes or inks that are not durable. The powder coating compositions of the present invention comprise a mixture of a first powder coating composition having a first shade and a second powder coating composition having a second shade different from the first. As used herein, the term "mixture" refers to a heterogeneous association of the first and second powder coating composition, wherein said compositions are not chemically combined and can be separated by a mechanical means. The first and second powder coating compositions can be mixed by any method such as, for example, dry mixing methods using high speed agitators such as the Henschsel mixer. In the present invention, as we describe here, producing powder coating compositions of a limited number of colors (fundamental colors) and, examining in advance, the ratio between the proportions of said compositions and the tones of the coatings obtained therewith, it can produce a powder coating composition of virtually any desired shade by selecting the powder coating compositions and blending them in the proper proportion so as to achieve the desired homogeneous coating tone without the need to subject the mixture to the extrusion process. As we indicated earlier, the first and / or second powder coating composition comprises particles enclosed in a polymer, which impart color. In certain embodiments, the first and second powder coating compositions comprise both particles enclosed in a polymer, which impart color. As used herein, the term "particles enclosed in a polymer" refers to particles that are at least partially enclosed by, ie confined within, a polymer to a degree sufficient to separate the particles from each other within the resulting coating, thus preventing a significant agglomeration of particles. It will be appreciated, of course, that the powder coating composition comprising said "particles enclosed in a polymer" may also include particles that are not encased in a polymer. As used herein, the term "particle imparting color" refers to a particle that significantly absorbs some wavelengths of visible light, ie, absorbs wavelengths between 400 and 700 nm, more than other wavelengths. wave of the visible region. In certain embodiments, the particles that are enclosed by a polymer comprise nanoparticles. As used herein, the term "nanoparticles" refers to particles that have an average particle size of less than 1 micron. In certain embodiments, the nanoparticles used in the present invention have an average particle size of 300 nanometers or less, for example, 200 nanometers or less or, in some cases, 100 nanometers or less. Therefore, in certain embodiments, the powder coating compositions comprise nanoparticles that are encased in the polymer and, therefore, are not significantly agglomerated. For the purpose of the present invention, the average particle size can be measured according to laser scattering techniques. For example, the average particle size can be determined using a Horiba Model LA 900 laser diffraction particle size measurement instrument, which uses a helium-neon laser with a wavelength of 633 nm to measure the particle size. and assume that the particle has a spherical shape, that is, the "particle size" refers to the smallest sphere that will completely enclose the particle. The average particle size can also be determined visually by examining an electron micrograph of a transmission electron microscope (TEM) image of a representative sample of the particles, measuring the diameter of the particles in the image and calculating the average primary particle size of the particles. the particles measured based on the magnification of the MET image. The skilled artisan will know how to prepare said MET image and determine the primary particle size based on the magnification. The primary particle size of a particle refers to the smallest diameter sphere that will completely enclose the particle. As used herein, the term "primary particle size" refers to the size of an individual particle. The shape (or morphology) of the particles can vary. For example, generally spherical morphologies (such as perlites, micro-pearlites or hollow spheres) can be used, as well as particles that are cubic, flat or acicular (elongated or fibrous). In addition, the particles can have an internal structure that is hollow, porous or void-free, or a combination of the above, for example, a hollow center with solid or porous walls. For more information on suitable particle characteristics see H. Katz et al., (Ed.), Handbook of Fillers and Plastics (1987), pages 9-10. According to the desired properties and characteristics of the powder coating composition (e.g. coating hardness, scratch resistance), stability or color), mixtures of one or more particles enclosed in a color imparting polymer having different average particle sizes can be used. The particles enclosed in a polymer, which impart color, for example, the nanoparticles, can be formed with polymeric and / or non-polymeric inorganic materials, polymeric and / or non-polymeric organic materials, composite materials, as well as mixtures of any of the foregoing. . As used herein, "formed with" has an open meaning, for example "comprises". That is, it is intended that a composition or substance "formed with" a list of components, be a composition comprising at least said enumerated components and, in addition, may comprise other components not mentioned, in the formation of the composition. In addition, as used herein, the term "polymer" includes oligomers and includes, without limitation, both homopolymers and copolymers. As used herein, the term "polymeric inorganic material" refers to a polymeric material having a main chain repeating unit based on a different element or elements of the carbon. Moreover, as used herein, the term "polymeric organic materials" refers to synthetic polymeric materials, semi-synthetic polymeric materials and natural polymeric materials, all of which have a carbon-based backbone repeating unit. The term "organic material", as used herein, refers to carbon-containing compounds where the carbon is generally bound to itself and to hydrogen and, often, to other elements as well, and excludes binary compounds such as for example , carbon oxides, carbides, carbon disulphide, etc., ternary compounds such as metal cyanides, metal carbonyls, phosgene, carbonyl sulphide, etc., and carbon-containing ionic compounds such as, for example, metal carbonates, for example, carbonate of calcium and sodium. As used herein, the term "inorganic material" refers to any material that is not organic. As used herein, the term "composite material" refers to a combination of two or more different materials. The particles formed with composite materials generally have a hardness on their surface that is different from the hardness of the internal portions of the particle below its surface. More specifically, the surface of the particle can be modified in any of the ways known in the art, including, but not limited to, the physical or chemical change of the surface characteristics using techniques known in the art. For example, a particle can be formed from a primary material coated, coated or encapsulated with one or more secondary materials to form a composite particle having a softer surface. In certain embodiments, the particles formed from composite materials can be prepared with a primary material that is coated, coated or encapsulated with a different form of the primary material. For more information on particles useful in the present invention, see G. Wypych, Handbook of Fillers, Second Edition, (1999), pages 15-202. As mentioned above, the particles useful in the present invention can include any inorganic material known in the art. Suitable particles can be formed from ceramic materials, metallic materials and mixtures of any of the foregoing. Non-limiting examples of such ceramic materials may comprise metal oxides, mixed metal oxides, metal nitrides, metal carbide, metal sulfide, metal silicate, metal borides, metal carbonates and mixtures of any of the foregoing. A specific, non-limiting example of a metal nitride is boron nitride; a specific, non-limiting example of a metal oxide is zinc oxide; non-limiting examples of suitable mixed metal oxides are aluminum silicates and magnesium silicates; non-limiting examples of suitable metal sulfides are molybdenum disulphide, tantalum disulphide, tungsten disulphide and zinc sulfide; non-limiting examples of metal silicates are aluminum silicates and magnesium silicates, such as, for example, vermiculite.

In certain embodiments of the present invention, the particles comprise inorganic materials selected from aluminum, barium, bismuth, boron, cadmium, calcium, cerium, cobalt, copper, iron, lanthanum, magnesium, manganese, molybdenum, nitrogen, oxygen, phosphorus, selenium. , silicon, silver, sulfur, tin, titanium, tungsten, vanadium, yttrium, zinc and zirconium, including oxides, nitrides, phosphides, phosphates, selenides, sulphides, sulfates and mixtures thereof. Suitable non-limiting examples of the above inorganic particles include silica, titanium, cerium, zirconium, bismuth oxide, magnesium oxide, iron oxide, aluminum silicate, boron carbide, titanium doped with nitrogen and cadmium selenide. The particles may comprise, for example, a core of essentially a simple inorganic oxide, such as silica in the colloidal, smoked or amorphous form, alumina or colloidal alumina, titanium dioxide, iron oxide, cesium oxide, yttrium oxide, yttrium. colloidal, zirconium, for example, colloidal or amorphous zirconium, and mixtures of any of the foregoing; or an inorganic oxide of the type on which an organic oxide of another type is deposited. The non-polymeric, inorganic materials useful in forming the particles used in the present invention may comprise inorganic materials selected from graphite, metals, oxides, carbides, nitrides, borides, sulfides, silicates, carbonates, sulfates and hydroxides. A non-limiting example of a useful inorganic oxide is zinc oxide. Non-limiting examples of suitable inorganic sulfides include molybdenum disulphide, tantalum disulphide, tungsten disulphide and zinc sulfide. Non-limiting examples of useful inorganic silicates include aluminum and magnesium silicates, such as, for example, vermiculite. Non-limiting examples of suitable metals include molybdenum, platinum, palladium, nickel, aluminum, copper, gold, iron, silver, alloys and mixtures of any of the foregoing.

In certain embodiments, the particles can be selected from fumed silica, amorphous silica, colloidal silica, alumina, colloidal alumina, titanium dioxide, iron oxide, cesium oxide, yttrium oxide, colloidal yttrium, zirconium, colloidal zirconium and mixtures of any of the previous ones. In certain embodiments, the particles comprise colloidal silica. As described above, these materials can be treated or not treated on the surface. Other useful particles include surface modified silicas such as those described in U.S. Patent No. 5,853,809 in column 6, line 51 to column 8, line 43, incorporated herein by reference. As another alternative, a particle can be formed from a primary material that is coated, coated or encapsulated with one or more secondary materials to form a composite material having a harder surface. Alternatively, a particle can be formed from a primary material that is coated, coated or encapsulated with a shape different from that of the primary material to form a composite material having a harder surface. In one example, and not limited to the present invention, an inorganic particle formed from an inorganic material such as silicon carbide or aluminum nitride, with a silica, carbonate or nanoclay coating can be provided to form a useful composite particle. . In another non-limiting example, a coupling agent with alkyl side chains can interact with the surface of an inorganic particle formed from an inorganic oxide to provide a useful composite particle having a "softer" surface. Other examples include coating, encapsulating or coating particles formed of non-polymeric or polymeric materials with different non-polymeric or polymeric materials. A specific non-limiting example of such composite particles is DUALITE ™, which is a synthetic polymer particle coated with calcium carbonate sold by Pierce and Stevens Corporation of Buffalo, NY.

In certain embodiments, the particles used in the present invention have a laminar structure. The particles having a laminar structure are composed of sheets or plates of atoms in hexagonal arrangement, with strong bonds within the sheet and weak van der Waals bonds between the sheets, thus providing a low cut resistance between the sheets. A non-limiting example of a laminar structure is a hexagonal crystal structure. Inorganic solid particles having a fullerene lamellar structure (Buckminster Fuller) are also useful in the present invention. Non-limiting examples of suitable materials having a laminar structure include boron nitride, graphite, mica dicalcogene, talc, gypsum, kaolinite, calcite, cadmium iodide, silver sulfide and mixtures thereof. Suitable metal dicalcogenides include molybdenum disulphide, molybdenum disodide, tantalum disulphide, tantalum disenlenide, tungsten disulphide, tungsten diselenide and mixtures thereof. The particles can be formed with non-polymeric organic materials. Non-limiting examples of organic, non-polymeric materials useful in the present invention include, but are not limited to, stearates (such as, for example, zinc stearate and aluminum stearate), diamond, carbon black and stearamide. The particles used in the present invention can be formed from inorganic polymeric materials. Non-limiting examples of the inorganic polymeric materials include polyphosphazenes, polysilanes, polysiloxanes, polygerman, polymeric sulfur, polymeric selenium, silicones, and mixtures of any of the foregoing. A specific non-limiting example of a particle formed from an inorganic polymeric material suitable for use in the present invention is Tospearl, which is a particle formed by cross-linked siloxanes and is marketed by Toshiba Silicones Company, Ltd. of Japan.

The particles can be formed from organic, synthetic polymeric materials. Non-limiting examples of suitable polymeric materials include, but are not limited to, thermosetting materials and thermoplastic materials. Non-limiting examples of suitable thermoplastic materials include thermoplastic polyesters, such as, for example, polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polycarbonates, polyolefins, such as, for example, polyethylene, polypropylene and polyisobutene, acrylic polymers such as, for example, copolymers of styrene and an acrylic acid monomer and polymers containing methacrylate, polyamides, thermoplastic polyurethanes, vinyl polymers and mixtures of any of the foregoing. Non-limiting examples of suitable thermosetting materials include thermosetting polyesters, vinyl esters, epoxy, phenolic, aminoplast, thermosetting polyurethanes and mixtures of any of the foregoing. A specific non-limiting example of a synthetic polymer particle formed from an epoxy material is an epoxy microgel particle. The particles may also be hollow formed from materials selected from polymeric and non-polymeric inorganic materials, polymeric and non-polymeric organic materials, composite materials and mixtures of any of the foregoing. Non-limiting examples of suitable materials from which hollow particles can be formed were cited above. In certain embodiments, the particles used in the present invention comprise an organic pigment, for example, azo compounds (monoazo, di-azo, β-naphthol, azo pigment lacquers such as Naphthol AS salt, benzimidazolone, di-azo condensation, isoindolinone, isoindoline) and polycyclic pigments (phthalocyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo, anthraquinone, indantrone, anthrapyrimidine, flavatrone, pyrantrone, antantrone, dioxazine, triarylcarbonium, quinophthalone) and mixtures of any of the foregoing. In certain embodiments, the organic material is selected from perylenes, quinacridones, phthalocyanines, isoindolines, dioxazines (ie triphenyloxazines), 1,4-diketopyrrolopyrroles, anthrapyrimidines, antantrones, flavatrones, indatrones, perinones, pyrantrones, thioindigos, 4, 4'-diamino-1, -diantraquinoyl, as well as the substituted derivatives and mixtures thereof. The perylene pigments used in the practice of the present invention may be unsubstituted or substituted. Substituted perylenes can be substituted on the imide and nitrogen atoms for example, and the substituents can include an alkyl group with 1 to 10 carbon atoms, an alkoxy group with 1 to 10 carbon atoms and a halogen (such as, for example, chlorine) or combinations thereof. The substituted perylenes may contain more than one of any of the substituents. The dimethyls and dianhydrides of perylene-3,4,9,10-tetracarboxylic acid are preferred. Crude perylenes can be prepared by methods known in the art. Fatalocyanine pigments, especially metal phthalocyanines, can be used. Although copper phthalocyanines are more readily available, other phthalocyanine pigments containing another metal such as those based on zinc, cobalt, iron, nickel and other metals can also be used. Metal free phthalocyanines are also suitable. The phthalocyanine pigments can be unsubstituted or partially substituted, for example, with one or more alkyls (having 1 to 10 carbon atoms), alkoxy (having 1 to 10 carbon atoms), halogens such as chlorine or other substituents typical of phthalocyanine pigments. The phthalocyanines can be prepared by any of the various methods known in the art. Typically, they are prepared by the reaction of italic anhydride, phthalonitrile or derivatives thereof with a metal donor, a nitrogen donor (e.g., urea or the same phthalonitrile) and an optional catalyst, preferably, in an organic solvent.

Quinacridone pigments, as used herein, include unsubstituted or substituted quinacridones (for example, with one or more alkyl, alkoxy, halogens such as chlorine or other substituents typical of quinacridone pigments) and are suitable for the practice of the present invention. The quinacridone pigments can be prepared by any of the various methods known in the art but preferably, they are prepared by thermally closing the ring of various 2,5-dianilinoterephthalic acid precursors in the presence of the polyphosphoric acid. Isoindoline pigments, which can optionally be substituted symmetrically or asymmetrically, are also suitable for the practice of the present invention and can be prepared by methods known in the art. A suitable isoindoline pigment, Pigmento Amarillo 139, is a symmetrical adduct of iminoisoindoline and barbituric acid precursors. The dioxazine pigments (ie triphenyloxazines) are also suitable organic pigments and can be prepared by methods known in the art. Mixtures of any of the inorganic particles and / or organic particles previously described can also be used. If desired, the particles described above can be formed into nanoparticles. In certain embodiments, the nanoparticles are formed in situ during the formation of an aqueous dispersion of particles enclosed in a polymer, as will be described in more detail below. In other embodiments, however, the nanoparticles are formed prior to their incorporation into the aqueous dispersion. In these embodiments, the nanoparticles can be formed by a number of methods known in the art. For example, nanoparticles can be prepared by spraying and sorting dry particulate material. For example, bulk pigments such as, for example, the inorganic and organic pigments described above, can be milled by grinding media to have a particle size of less than 0.5 millimeters (mm), or less than 0.3 mm. , or less than 0.1 mm. The pigment particles are typically milled to a nanoparticle size in a high-energy mill in one or more solvents (either water, organic solvent or mixture of the two), optionally in the presence of a vehicle for polymer milling. If necessary, a dispersant may be included, for example, (if in organic solvent), SOLSPERSE® 32000 or 32500 marketed by Lubrizol Corporation or, (if in water), SOLSPERSE® 27000, also marketed by Lubrizol Corporation. Other suitable methods for producing nanoparticles include crystallization, precipitation, gas phase condensation and chemical wear (i.e., partial dissolution). In certain embodiments, the color imparting particles enclosed in a polymer in the first and / or second powder coating composition are formed from an aqueous dispersion of particles enclosed in a color imparting polymer. As used herein, the term "dispersion" refers to a two-phase system where one phase includes finely divided particles distributed in a second phase, which is a continuous phase. The dispersions are often oil-in-water emulsions, where the aqueous medium provides the continuous phase of the dispersion in which the particles enclosed in the polymer are suspended as an organic phase. As used herein, the terms "aqueous", "aqueous phase", "aqueous medium" and the like, refer to a medium consisting exclusively of water or predominantly comprising water in combination with another material such as, for example, an organic solvent inert. In certain embodiments, the amount of organic solvent present in the aqueous dispersions of the present invention is less than 20 weight percent, eg, less than 10 weight percent or, in some cases, less than 5 weight percent , or, even in other cases, less than 2 percent by weight, percentages by weight based on the total weight of the dispersion. Non-limiting examples of suitable organic solvents are propylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monobutyl ether, n-butanol, benzyl alcohol and mineral spirits. The color imparting particles enclosed in a polymer used in the present invention comprise, for example, a polymer selected from acrylic polymers, polyurethane polymers, polyester polymers, polyether polymers, silicon-based polymers, copolymers and mixtures thereof. same. Said polymers can be produced by any method known to the person skilled in the art to which the present invention belongs. Suitable polymers include those described in U.S. Patent Application No. 10 / 876,031 in [0061] to [0076], the portion of which is incorporated herein by reference, and the Publication of U.S. Patent Application No. 1005/0287348 Al in [0042] to [0044], whose cited portion is incorporated herein by reference.

In certain embodiments, said aqueous dispersions comprise particles enclosed by a friable polymer. As used herein, the term "friable polymer" refers to a polymer that is easily sprayed at ambient conditions. That is, after the removal of liquid materials from the dispersion, the resulting solid material is easily broken into fragments or small parts which are suitable as dry feed material for an extruder to produce a powder coating composition. On the other hand, a film-forming polymer would form, after the removal of the liquid materials from the dispersion, a self-supporting continuous film on at least one horizontal surface of a substrate. As used herein, the term "environmental conditions" refers to the surrounding conditions which is often of an atmosphere of pressure, 50% relative humidity and 25 ° C. In certain embodiments of the present invention, the friable polymer comprises the reaction product of (i) a polymerizable polyurethane polyester and (ii) an ethylenically unsaturated monomer. As used herein, the term "polymerizable polyurethane polyester" refers to a polymer that includes a plurality of ester units, H R'-CO-R2 R1_JIJ_.C_0_.RJ 0 and a plurality of urethane units, or, has functional groups capable of being polymerized to form a larger polymer and, where R 1 is an alkyl, cycloalkyl or oxyalkyl moiety, R is an alkyl or cycloalkyl moiety and R is an alkyl, cycloalkyl, aralkyl or an aromatic moiety. In certain embodiments, the polymerizable polyurethane polyester comprises a polyurethane polyester having a terminal ethylenic unsaturation. As used herein, the phrase "terminal ethylenic unsaturation" refers to the fact that at least some of the terminal ends of the polyester polyurethane contain a functional group containing ethylenic unsaturation. Said polyester polyurethanes may also include, but do not necessarily include, an internal ethylenic unsaturation. As a result, in certain embodiments, the aqueous dispersions comprise a polymerizable polyurethane polyester having a terminal ethylenic unsaturation that is prepared with reagents comprising (a) a polyisocyanate, (b) a polyester polyol and (c) a material comprising a group ethylenically unsaturated and a group of active hydrogen. In certain embodiments, the polymerizable polyurethane polyester used in the aqueous dispersions of the present invention are formed with reagents further comprising (d) a polyamine and / or (e) a material comprising an acid functional group or an anhydride and a group functional reactive with isocyanate or hydroxyl groups. As used herein, the term "active hydrogen group" refers to functional groups that are reactive with isocyanates as determined by the Zerewitnoff test as described in JOURNAL OF THE AMERICAN CHEMICAL SOCIETY (Journal of the American Chemical Society), volume 49, page 3.181 (1927). Polyisocyanates suitable for use in the preparation of a polymerizable polyurethane polyester include the aliphatic, cycloaliphatic, araliphatic and / or aromatic isocyanates and mixtures thereof. Examples of useful aliphatic and cycloaliphatic polyisocyanates include 4,4-methylenebis-cyclohexyl diisocyanate (hydrogenated MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylenebis (cyclohexyl isocyanate), trimethyl hexamethylene diisocyanate (TMDI), meta-tetramethylxylylene diisocyanate. (TMXDI) and cyclohexylene diisocyanate (hydrogenated XDI). Other aliphatic polyisocyanates include isocyanurates of IPDI and HDI. Examples of suitable aromatic polyisocyanates include toluene diisocyanate (TDI) (ie, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate or mixtures thereof), diphenylmethane-4,4-diisocyanate (MDI), naphthalene-1,5-diisocyanate (NDI), 3,3-dimethyl-4,4-biphenylene diisocyanate (TODI), crude TDI (ie, a mixture of TDI and an oligomer thereof), polymethylenepolyphenyl polyisocyanate, crude MDI (ie, a mixture of MDI and an oligomer thereof), silylene diisocyanate (XDI) and phenylene diisocyanate. Suitable are polyisocyanate derivatives prepared from hexamethylene diisocyanate, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane ("IPDI"), including isocyanurates thereof and / or 4,4'-bis (isocyanatocyclohexyl) )methane. In certain embodiments, the amount of polyisocyanate used to prepare the polymerizable polyurethane polyester is within a range between 20 and 70 weight percent, eg, between 30 and 60 weight percent or, in some cases, between 40 and 50 weight percent, the percentages by weight being based on the total weight of the resin solids used to prepare the polymerizable polyurethane polyester. Polyester polyols suitable for use in the preparation of the polymerizable polyurethane polyester can be prepared by any of the suitable methods, for example, by using the saturated dicarboxylic acids or anhydrides thereof (or combinations of acids and anhydrides) and polyhydric alcohols or by ring of caprolactones, for example, epsilon caprolactone. Said polyester polyols are marketed in various molecular weights. Suitable aliphatic dicarboxylic acids for preparing polyesters include those containing from 4 to 14, for example, from 6 to 10, carbon atoms, inclusive. Examples of said dicarboxylic acids include: succinic acid, glutamic acid, atypical acid, pimelic acid, suberic acid, azelaic acid and sebasic acid. The corresponding anhydrides can also be used. Typically, adipic and azelaic acids are used. The polyhydric alcohols used in the preparation of polyester polyols suitable for use in the preparation of polymerizable polyurethane polyester used in certain embodiments of the present invention, include, without limitation, aliphatic alcohols containing at least 2 hydroxy groups, for example, chain glycols. straight containing between 2 and 15, for example, between 4 and 8, inclusive carbon atoms. In certain embodiments, the glycols contain hydroxyl groups at the terminal positions. Non-limiting examples of said polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,3-propane diol, 1,3-butane diol, 1,4-butane diol, 1,5-pentane diol, , 2-dimethylpropane diol, 1,5-hexane diol, 1,7-heptane diol, 1,8-octane diol, 1,10-decane diol and mixtures of said polyhydric alcohols. In certain embodiments, the polyester polyol is prepared by reacting a dicarboxylic acid (or anhydride thereof) with a polyhydric alcohol in the presence of an esterification catalyst, for example, an organ tin catalyst. The amount of acid and alcohol used will vary and will depend on the polyester of the desired molecular weight. The hydroxyl-terminated polyesters are obtained by using excess alcohol to obtain linear chains containing a preponderance of terminal hydroxyl groups. Examples of polyesters include: poly (1,4-butylene adipate), poly (1,4-butylene succinate), poly (1,4-butylene glutarate), poly (1,4-butylene pimelate), poly (1,4-butylene suberate), poly (1,4-butylene azelate), poly (1,4-butylene sebacate) and poly (epsilon caprolactone). In certain embodiments, the polyester polyol used to prepare the polymerizable polyurethane polyester used in the aqueous dispersions of the present invention have an average molecular weight between 500 and 3000, for example, between 500 and 2500 or, in certain cases, between 900 and about of 1,300. In certain embodiments, the amount of polyester polyol used to prepare the polymerizable polyurethane polyester included in certain embodiments of the present invention is between 10 and 60 weight percent, for example, between 20 and 50 percent by weight or, in some cases, between 30 and 40 percent by weight, the percentages by weight being based on the total weight of the resin solids used to prepare the polymerizable polyurethane polyester. As indicated, the polymerizable polyurethane polyester present in certain embodiments of the present invention is formed from a material comprising an ethylenically unsaturated group and an active hydrogen group. Suitable ethylenically unsaturated groups include, for example, acrylates, methacrylates, allyl carbamates and allyl carbonates. The functional groups of acrylate and methacrylate can be represented by the formula: CH2 = C (R?) - C (O) O, where Ri is hydrogen or methyl. The allyl carbamates and carbonates can be represented by the formulas: CH2 = CH-CH2-NH-C (O) O- and CH2 = CH-CH2-O- (O) O-, respectively. In certain embodiments, the material comprising an ethylenically unsaturated group and an active hydrogen group used to prepare the polymerizable polyurethane polyester comprises a hydroxyalkyl (meth) acrylate. The hydroxyalkyl (meth) acrylates include those having 1 to 18 carbon atoms in the alkyl radical, said alkyl radical being substituted or unsubstituted. Specific non-limiting examples of such materials include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, hexane-1, 6-diol mono (mef) acrylate, 4-hydroxybutyl (met) acrylate, as well as their mixtures. As used herein, the term "(meth) acrylate" is intended to include both: acrylates and methacrylates. In certain embodiments, the amount of material comprising an ethylenically unsaturated group and an active hydrogen group used to prepare the polymerizable polyurethane polyester is comprised within a range between 1 and 12 weight percent, eg, between 2 and 12 weight percent. 8 percent by weight or, in some cases, between 4 and 6 percent by weight, the percentages by weight being based on the total weight of the resin solids used to prepare the polymerizable polyurethane polyester. As previously indicated, in certain embodiments, the polymerizable polyurethane polyester is formed from a polyamine. Useful polyamines include, but are not limited to, primary or secondary diamines or polyamines in which the groups attached to the nitrogen atoms may be saturated or unsaturated, aliphatic, alicyclic, aromatic, aromatic-substituted aliphatic, substituted aliphatic aromatic and heterocyclic. Suitable exemplary aliphatic and alicyclic diamines include 1,2-ethylene diamine, 1,2-porphylene diamine, 1,8-octane diamine, isophorone diamine, propane-2,2-cyclohexyl diamine, and the like. Exemplary suitable aromatic diamines include phenylene diamines and toluene diamines, for example, o-phenylene diamine and p-tolylene diamine. These and other suitable polyamines are described in detail in U.S. Patent No. 4,046,729 in column 6, line 61 to column 7, line 26, which portion is incorporated herein by reference. In certain embodiments, the amount of polyamine used to prepare the polymerizable polyurethane polyester is within a range between 0.5 and 5 percent by weight, for example, between 1 and 4 percent by weight or, in some cases , between 2 and 3 weight percent, the weight percentage being based on the total weight of the resin solids used to prepare the polymerizable polyurethane polyester. As previously indicated, in certain embodiments, the polymerizable polyurethane polyester is formed from a material comprising an acid or anhydride functional group and a functional group reactive with the isocyanate or hydroxyl groups of other components from which, it is formed the polyurethane material. Useful acid functional materials include those compounds having the structure: X-Y-Z where X is OH, SH, NH2 or NHR and R include alkyl, aryl cycloalkyl, substituted alkyl, substituted aryl and substituted cycloalkyl groups and mixtures thereof; Y includes alkyl, aryl, cycloalkyl, substituted alkyl, substituted aryl and substituted cycloalkyl groups and mixtures thereof; and Z includes OSO3H, COOH, OPO3H2, SO2OH, POOH and PO3H2 and mixtures thereof. Examples of suitable acid functional materials include hydroxypivalic acid, 3-hydroxy butyric acid, D, L-tropic acid, D, L hydroxy malonic acid, D, L-malic acid, citric acid, thioglycolic acid, glycolic acid, amino acid, 12-hydroxy stearic acid, dimethylol propionic acid, mercapto propionic acid, mercapto butyric acid, mercapto-succinic acid and mixtures thereof. Useful anhydrides include aliphatics, cycloaliphatics, olefins, cycloolefins and aromatics. Aliphatic and substituted aromatic anhydrides are also useful if the substituents do not adversely affect the reactivity of the anhydride or the properties of the resulting polyurethane. Examples of substituents include chloro, alkyl and alkoxy. Examples of anhydrides include succinic anhydride, methylsuccinic anhydride, dodecenyl succinic anhydride, octadecenylsuccinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, alkyl anhydrides hydrophthalic such as methylhexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylene tetrahydrophthalic, trimellitic anhydride, chlordened anhydride, itaconic anhydride, citraconic anhydride, maleic anhydride and mixtures thereof. In certain embodiments, the acid or anhydride functional material provides the polymerizable polyurethane polyester with anionic ionizable groups that can be ionized by solubilizing the polymer in water. As a result, in certain embodiments, the polymerizable polyurethane polyester present in certain embodiments of the aqueous dispersions of the present invention is dispersible in water. As used herein, the term "water dispersible" means that a material can be dispersed in water without the aid or use of a surfactant. As used herein, the term "ionizable" refers to a group capable of becoming ionic, that is, capable of dissociating into ions or being electrically charged. An acid can be neutralized with a base to form a carboxylate salt group. Examples of anionic groups include -OSO3, -COO ~, -OPO3 \ -SO2O, -POO ", and PO3". In certain embodiments, the amount of material comprising an acid or anhydride functional group and an isocyanate-reactive functional group or hydroxyl groups used to prepare the polymerizable polyurethane polyester is comprised within a range between 5 and 20 weight percent, by example, between 7 and 15 weight percent or, in some cases, between 8 and 12 weight percent, the percentages by weight being based on the total weight of the resin solids used to prepare the polymerizable polyurethane polyester. As indicated, in certain embodiments, the acid groups are neutralized with a base. The neutralization may be within a range between about 0.6 and about 1.1, for example, between 0.4 and 0.9 or, in some cases, between 0.8 and 1.0 of the equivalent of total theoretical neutralization. Suitable neutralizing agents include inorganic and organic bases such as, for example, sodium hydroxide, potassium hydroxide, ammonia, amines, alcohol amines having at least one secondary or tertiary primary amino group and at least one group hydroxyl Suitable amines include alkanolamines such as, for example, monoethanolamine, diethanolamine, dimethylaminoethanol, diisopropanolamine and the like.

The polymerizable polyurethane polyester used in certain embodiments of the present invention may be formed by combining the components identified above in a suitable arrangement. For example, the polymerizable polyester polyurethane can be prepared by solution polymerization techniques known to those skilled in the art to which the present invention pertains. As is obvious from the above description, the polymerizable polyurethane polyester present in certain embodiments of the present invention can be nonionic, anionic or cationic. In certain embodiments, the polymerizable polyurethane polyester will have an average molecular weight of less than 150,000 grams per mole, for example, between 10,000 and 100,000 grams per mole, or, in some cases, between 40,000 and 80,000 grams per mole. The molecular weight of the polyurethane and other polymeric materials in the practice of the invention is determined by gel permeation chromatography using a standard polystyrene.

As previously indicated, in certain embodiments of the present invention, a friable polymer is present comprising the reaction product of (i) a polymerizable polyurethane polyester as previously described and (ii) an ethylenically unsaturated monomer. Suitable ethylenically unsaturated monomers include any of the polymerizable ethylenically unsaturated monomers including vinyl monomers known in the art. Non-limiting examples of the monomers containing an ethylenically unsaturated carboxylic acid functional group include: (meth) acrylic acid, beta-carboxyethyl acrylate, acryloxypropionic acid, crotonic acid, fumaric acid, fumaric acid monoalkyl esters, maleic acid, monoalkyl esters of maleic acid, itaconic acid, monoalkyl esters of itaconic acid and mixtures thereof. As used herein, "(meth) acrylic" and the derivative terms purport to include both: acrylic and methacrylic. Non-limiting examples of other free ethylenically unsaturated monomers of carboxylic acid functional groups include alkyl esters of (meth) acrylic acids for example, ethyl (meth) acrylate, methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl ( met) acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxy butyl (meth) acrylate, isobornyl (meth) acrylate, lauryl (meth) acrylate and ethylene glycol di (meth) acrylate; vinyl aromatics such as, for example, styrene and vinyl toluene; (meth) archilamides such as, for example, N-butoxymethyl archilamide; acrylonitriles, dialkyl esters of maleic and fumaric acids; vinyl halides and vinylidene vinyl acetate; vinyl ethers; allyl ethers; allyl alcohols; derivatives and mixtures thereof. The ethylenically unsaturated monomers may also include functional monomers of ethylenically unsaturated beta-hydroxy ester such as those derived from the reaction of an ethylenically unsaturated acid functional monomer, such as the monocarboxylic acid, for example, acrylic acid, and an epoxy compound not participating in the polymerization initiated with free radical with the unsaturated acid monomer. Examples of said epoxy compounds are glycidyl ethers and esters. Suitable glycidyl ethers include the glycidyl ethers of alcohols and phenols such as, for example, butyl glycidyl ether, octal glycidyl ether, phenyl glycidyl ether and the like. In certain embodiments, the polymerizable polyurethane polyester and the ethylenically unsaturated monomer are present in the aqueous dispersions of the present invention in a weight ratio of 95: 5 to 30:70, eg, 90:10 to 40:60 or, in some cases, 80:20 to 60:40. The aqueous dispersions of the present invention are prepared by a method comprising: (A) providing a mixture, in an aqueous medium of (i) color imparting particles, (ii) one or more polymerizable ethylenically unsaturated monomers and / or, ( iii) a mixture of one or more polymerizable unsaturated monomers with one or more polymers; and / or (iv) one or more polymers and then subjecting the mixture to high cut conditions in the presence of an aqueous medium. Such methods are described in detail in U.S. Patent Application No. 10 / 876,031 in [0054] to [0090], which portion is incorporated herein by reference, and U.S. Patent Application Publication No. 2005/0287348 Al in [0036] to [0050], the portion of which is incorporated herein by reference. In certain embodiments, however, the aqueous dispersions are prepared by a method comprising: (1) providing a mixture, in an aqueous medium, of (i) color imparting particles, (ii) an ethylenically unsaturated polymerizable monomer and (iii) ) a water-dispersible polymerizable dispersant, and (2) polymerizing the ethylenically unsaturated monomer and the polymerizable dispersant to form the particles enclosed in the color imparting polymer comprising a water dispersible polymer. In these embodiments, the polymerizable dispersant can comprise any polymerizable material which is water dispersible and which, after polymerization with the ethylenically unsaturated monomer, produces particles enclosed in a color imparting polymer and comprise a water dispersible polymer, in some, cases, a friable polymer dispersible in water. In certain embodiments, the polymerizable dispersant comprises the water dispersible polyester polyurethane described above having a terminal ethylenic unsaturation. In these embodiments, the water-dispersible polymerizable dispersant is capable of dispersing itself and other materials, including ethylenically unsaturated monomers, in the aqueous medium, without the need for surfactants or high shear conditions. Thus, the above method for preparing an aqueous dispersion of particles enclosed in a polymer, imparting color, is particularly suitable in situations where it is not desired or possible to use the high cut conditions described in US Patent Application No. 10 / 876,031 in [0081] to [0084] and U.S. Patent Application Publication No. 2005/0287348 Al in [0046]. Therefore, in certain embodiments, the aqueous dispersion of particles enclosed in a color-imparting polymer is prepared by a method that does not include the step of subjecting the mixture of color-imparting particles to high-cut conditions to the ethylenically polymerizable monomer. unsaturated and the polymerizable dispersible dispersible in water. In addition, the above method of the present invention allows the formation of nanoparticles in situ, instead of requiring the formation of nanoparticles prior to the preparation of the aqueous dispersion. In these methods, particles having an average particle size of 1 micron or more, after being mixed with the ethylenically unsaturated monomer and the polymerizable dispersible dispersible in water in the aqueous medium, can be formed into nanoparticles (ie, the nanoparticles they are formed in situ). In certain embodiments, nanoparticles imparting color are formed by subjecting the aqueous medium to spray conditions. For example, the particles can be ground with a grinding medium that produces a particle size of less than 0.5 millimeters, or less than 0.3 millimeters or, in some cases, less than 0.1 millimeters. In these embodiments, the particles can be ground to the nanoparticle size with a high energy mill in the presence of an aqueous medium, the polymerizable ethylenically unsaturated monomer and the polymerizable dispersible dispersible in water. If desired, another dispersant can be used, such as SOLSPERSE 2700, marketed by Avecia, inc. As indicated, the above methods for preparing aqueous dispersions of the particles enclosed in the polymer, which impart color, include the step of polymerizing the ethylenically unsaturated monomer and the polymerizable dispersant to form the particles enclosed in the color imparting polymer and comprising a polymer dispersible in water. In certain embodiments, at least a portion of the polymerization occurs during the formation of nanoparticles, if applicable. In addition, a free radical initiator can be used. Both can be used: initiators soluble in water and in oil. Non-limiting examples of suitable water-soluble initiators include ammonium peroxydisulfate, potassium peroxydisulfate and hydrogen peroxide. Non-limiting examples of water-soluble initiators include t-butyl hydroperoxide, dilauryl peroxide and 2,2'-azobis (isobutyronitrile). In many cases, the reaction is carried out at a temperature between 20 ° and 80 ° C. The polymerization can be carried out either in a batch or continuous process. The amount of time necessary to carry out the polymerization may be within a range between, for example, 10 minutes to 6 hours, if this time is sufficient to form a polymer in situ from one or more of the ethylenically active monomers. unsaturated Once the polymerization process is completed, the resulting product is a stable dispersion of particles enclosed in a polymer, which impart color, in an aqueous medium that may contain some organic solvent. Part or all of the organic solvent can be removed by distillation under reduced pressure at a temperature, for example below 40 ° C. As used herein, the term "stable dispersion" or "stably dispersed" refers to the particles enclosed in the polymer needing to settle, not coagulate or flocculate in the aqueous medium after standing. In certain embodiments, the particles enclosed in the polymer are present in the aqueous dispersions of the present invention in an amount of at least 10% by weight or in an amount between 10 and 80 percent by weight, or in an amount between 25 and 21 50 percent by weight, or in an amount between 25 and 40 percent by weight, the percentages by weight being based on the weight of total solids in the dispersion.

In certain embodiments, the dispersed particles enclosed in the polymer have a maximum light diffusion of 10% or, in some cases, 5% or, even in other cases, 1% or, in other embodiments, 0.5%. As used herein the "diffusion of light" is determined by ASTM DI 003. The values of light diffusion of the particles enclosed in the polymer described here are first determined by obtaining the particles, for example, nanoparticles, dispersed in a liquid ( for example, water, organic solvent and / or a dispersant, as described above) and then measuring these dispersions diluted in a solvent, for example, butyl acetate, using a Byk-Gardner TCS (The Color Sphere) instrument having a length of cell passage of 500 microns. As the% light diffusion of a liquid sample depends on the concentration, the% light diffusion here is reported as the transmittance of between about 15% and about 20% maximum absorbance wavelength. An acceptable diffusion of light for relatively large particles can be achieved when the difference between the refractive index between the particles and the surrounding medium is low. Conversely, for smaller particles, the greater differences in the refractive index between the particle and the surrounding medium can provide an acceptable diffusion of light. In certain embodiments, especially when the particles enclosed in the polymer comprise a friable polymer, the aqueous dispersion of the particles enclosed in a polymer, imparting color, can be further processed: (1) removing the water from the aqueous dispersion to form a material solid comprising the particles enclosed in the polymer, imparting color, and, (2) fragmenting the solid material. In these embodiments, water can be removed from the aqueous dispersion by any suitable drying method, for example, the use of a drum dryer, roller dryer, spray dryer or the like. Moreover, the solid material can be fragmented by any suitable technique, for example the use of hammer mill or similar technique. After the fragmentation, the resulting granules can be reprocessed, for example, sifted in a sorter, before packaging. In the present invention, the particles enclosed in the polymer, which impart color, are incorporated into a powder coating composition. In addition to the particles enclosed in the polymer, said powder coating compositions may comprise a particulate film-forming resin. The particulate film-forming resins include, for example, an epoxy resin, for example, an acrylic polymer containing an epoxy group or a polyglycidyl ether of a polyhydric alcohol and a curing agent suitable for the epoxy resin, such as, for example, a material containing a polyfunctional carboxylic acid group or a dicyanamide. Examples of curable particulate resinous materials are described in U.S. Patent Application No. RE 32,261 and U.S. Patent No. 4,804,581, incorporated herein by reference. Examples of other suitable particulate film-forming resins are functional carboxylic acid resins, for example, functional carboxylic acid polyesters and acrylic polymers and curing agents suitable for such materials as, for example, triglycidyl isocyanurate and beta-hydroxyalkylamide, as described in U.S. Patent No. 4,801,680 and U.S. Patent No. 4,988,767, incorporated herein by reference. In certain embodiments, the powder coating compositions comprise between 60 and 80 weight percent of the particulate film-forming resin, based on the total weight of the powder coating composition. In certain embodiments, the powder coating compositions of the present invention contain between 0, 1 and 50 weight percent, eg, between 1 and 20 weight percent, of particles enclosed in the polymer, based on the total weight of the powder coating composition. The powder coating compositions may optionally include other materials such as other pigments, filler carriers, light stabilizers, flow modifiers, anti-bursting agents and antioxidants. Suitable pigments include, for example, titanium dioxide, ultramarine blue, phthalocyanine blue, phthalocyanine green, carbon black, graphite fibers, black iron oxide, chromium green oxide, ferride yellow and quinde red. Anti-bursting agents can be added to the composition to allow any volatile material to escape from the film during baking. A commonly preferred anti-burst agent is benzoin and, when used, is generally present in amounts between 0.5 and 3 percent by weight based on the total weight of the powder coating composition. In certain embodiments, the powder coating compositions include fumed silica or the like to reduce the caking of the powder during storage. An example of fumed silica is marketed by Cabot Corporation under the trade name CAB-O-SIL. The fumed silica is present in amounts of between 0.1 and 1 weight percent based on the total weight of the powder coating formulation. The particles enclosed in a color imparting polymer can be incorporated into the powder coating composition by a variety of methods. For example, in embodiments where the particles enclosed in the polymer comprise a friable polymer, said particles imparting color and other components are included in particulate and dry form, mixed together and then melt-mixed in an extruder. However, in other embodiments, in cases where the aqueous dispersion of particles enclosed in a polymer not comprising a friable polymer is used, said color imparting particles are incorporated into the powder coating composition by the following method: (1) introducing into the extruder, the components of the powder coating composition comprising: (a) an aqueous dispersion of particles enclosed in a polymer, which impart color, and (b) dry materials; (2) mix (a) and (b) in the extruder; (3) devolatilizing the mixture to form an extrudate; (4) cool the extrudate, and (5) grind the extrudate to achieve the desired particle size. As used herein, the term "devolatilize" means to remove volatile materials including water and organic solvents. In certain embodiments, said powder coating compositions are prepared by a method and / or apparatus described in U.S. Patent Publication No. 2005 / 0212159A1; 2005 / 0213423A1; and / or 2005 / 0212171A1, whose relevant descriptions are incorporated herein by reference. In the above methods, the dry materials can include the particulate film-forming resin described above as well as other additives for the composition. Dry materials can first be mixed with a high-cut mixer such as a planetary mixer. In certain embodiments, the dry materials and the aqueous dispersion of the present invention are then mixed in an extruder at a temperature between 80 ° C and 150 ° C. Then the extrudate is cooled and pulverized to form a particulate mixture. According to the present invention, the powder coating composition comprising particles enclosed in a polymer, imparting color, is mixed with another powder coating composition which can and often does also include particles enclosed in a polymer that imparts color to form the powder coating composition of the present invention. In addition to the particles enclosed in a color imparting polymer, the powder coating compositions may comprise a particulate film-forming resin as described above. In certain embodiments, the film-forming resin present in the powder coating composition is the same as, or at least compatible with, the film-forming resin present in the second coating composition. As indicated above, the mixture of the first and second powder coating composition produces a powder coating composition of the present invention which, after its direct application on at least a portion of a substrate and its curing, produces a decorative and durable coating having a homogeneous shade different from the tone of the powder coating compositions from which it was formed. In other words, the powder coating compositions of the present invention are capable of producing a decorative and durable coating having a homogeneous shade different from the first and second tone. As used herein, "direct application" and similar phrases means that the powder coating composition does not need to be subjected to the Extrusion Process before its application. As used herein, the term "homogeneous tone different from the first and second tone" means that the coating can be recognized by an aperson as a homogeneous tone different from the first and second when viewed with the naked eye, at any distance from the coating , even at distances of 30 cm or less. In other words, the coating does not have the appearance of "salt and pepper" (mottled) in which the first and second tone are distinguished by visual examination with the naked eye. As used herein, the term "tone" refers to the quality of a color determined by its dominant wavelength.

The powder coating compositions of the invention can be applied to a variety of substrates including metal substrates, for example, aluminum and steel substrates. The coating compositions are often applied by spraying and, in the case of a metal substrate, by electrostatic spraying or by the use of a fluidized bed. The powder coating compositions can be applied in a single sweep or in several passes to obtain a film with a thickness after curing of between about 1 and 10 mils (25 to 250 microns), usually between about 2 and 4 mils ( 50 to 100 micrometers). In many cases, after application of the powder coating composition, the coated substrate is heated to a temperature sufficient to cure the coating, often at a temperature between 121.1 ° C and 260.0 ° C during 1 to 60 minutes, for example, between 148.9 ° C to 204.4 ° C for 15 to 30 minutes. As a result, the present invention also relates to articles, for example, metal articles, at least partially coated by a decorative and durable coating having a homogeneous hue. The decorative and durable coating is deposited directly with a powder coating composition comprising a mixture of a first powder coating composition having a first shade and a second powder coating composition having a second shade different from the first, wherein the first and / or second powder coating composition comprises particles enclosed in a polymer that impart color. In the articles of the present invention, the homogeneous tone is different from the first and second tone. In certain embodiments, the decorative and durable coating having a homogeneous shade is also a clear coating. As used herein, "transparent coating" refers to a coating layer deposited on a substrate, where the surface below the coating layer is visible to the naked eye. In certain embodiments of the present invention, the surface below the transparent coating layer is visible when the transparent layer is applied with a dry film thickness of between 0.5 to 5.0 mils (12.7 to 127 microns). One way to evaluate transparency is by measuring opacity. As used herein, "opacity" refers to the degree of darkening that the material produces on the substrate.

"Percent opacity" refers here to the relationship between the reflectance of a dry coating film on a black substrate with a reflectance of 5% or less, with the reflectance of the same coating film, applied and dried in an equivalent manner, on a substrate with a reflectance of 85%. The percent opacity of a dry coating film will depend on the dry film thickness of the coating and the concentration of the color imparting particles. In certain embodiments of the present invention, the transparent coating layer that imparts color has a percent opacity not exceeding 90 percent, for example, not greater than 50 percent, with a dry film thickness of one (1) thousand ( around 25 microns). The powder coating compositions of the present invention can be used to form a decorative and durable simple coating, for example, a monolayer, a base layer in a two-layer system or both; or as one or more layers of a multi-layer system including a final coating compositions, a dye layer and / or a basecoating composition and / or a primer layer including, for example, a primer by electrodeposition and / or a base layer of surface. The present invention also relates to substrates at least partially coated with a multi-layer composite coating where at least one coating layer is deposited with a powder coating composition of the present invention. In certain embodiments, for example, the powder coating composition of the present invention comprises a base layer in a multi-layer composite coating comprising a base layer and a final layer. As a result, in these embodiments, after application and curing of the powder coating composition of the present invention, at least one final cover layer can be applied to the base coat. The final cover can, for example, be deposited with a powder coating composition, an organic solvent based or water based coating composition, such as those known in the art. The final cover film-forming composition can be any of the compositions useful in coating applications including, for example, a film-forming composition comprising a resinous binder selected from acrylic polymers, even alkyd polyesters, and polyurethanes. The final coating composition can be applied by any of the conventional coating techniques such as, for example, by brush, by spraying, dipping or as a fluid but more frequently, it is applied by spraying. You can use the spray techniques and the most usual equipment for air, airless and electrostatic spraying, both manual and automatic. As will be obvious from the above description, the present invention also relates to methods for preparing a decorative and durable coating having a homogeneous shade. These methods comprise: (a) providing a first powder coating composition having a first shade, (b) providing a second powder coating composition having a second shade different from the first, (c) mixing the first and second composition. powder coating and (d) directly applying the mixture to at least a portion of a substrate. In these methods, the first and / or second powder coating composition comprises particles enclosed in a polymer that impart color. In certain embodiments, the present invention is presented in the form of a team. As used herein the term "equipment" refers to a group of articles that are used together. In these embodiments, the present invention relates to a device comprising: (a) a first container comprising a powder coating composition having a first shade, and (b) a second container comprising a powder coating composition having a second shade different from the first. In the equipment of the present invention, the first and / or the second container comprises a powder coating composition that includes particles enclosed in a polymer that impart color and, after mixing the contents of the first with the second container, forms a powder coating composition which, after being directly applied to at least a portion of a substrate and cured, produces a decorative and durable coating having a homogeneous shade different from the first and second shade. Furthermore, in certain embodiments, the present invention relates to a method for producing a coating of a selected shade, that is, a color matching the chosen one is formed, from a mixture of two or more powder coating composition.

These methods comprise: (a) providing a first powder coating composition having a first shade, (b) providing a second powder coating composition having a second shade different from the first, (c) mixing the first and second composition. powder coating in a proportion that results in a coating having the selected shade when the mixture is applied directly to at least a portion of a substrate and cured. In these methods, the first and / or second powder coating composition comprises particles enclosed in a polymer that impart color. The following examples illustrate the invention which should not be considered limited to the details thereof. All parts and percentages in the examples, as well as throughout the specification, are by weight unless otherwise indicated. EXAMPLES EXAMPLE 1 Polyurethane dispersion This example describes the preparation of a polyurethane dispersion which was subsequently used in the form of polyurethane / nanopigment dispersions of Examples 2 to 3. The polyurethane dispersion was prepared from the mixture of the following ingredients in the indicated relationships: The polyurethane dispersion was prepared in a four-neck round base flask equipped with an electronic temperature probe, mechanical stirrer, condenser and a heating blanket. Charge I was stirred for 5 minutes in the flask at a temperature of 125 ° C. Charge II was added and the mixture was cooled to 70 ° C. Load III was added for a period of 10 minutes. Charge IV was added and the resulting mixture was gradually heated to 90 ° C for 90 minutes and then maintained at 90 ° C for 1 hour. Charge V was stirred in a separate flask and heated to 60 ° C. 1,387.8 grams of the reaction product of Charges I, II, III and IV were added to Charge V for 10 minutes. Charge VI was added and the resulting mixture was cooled to room temperature. The final product was a translucent emulsion with an acid value of 12.5, a Brookfield viscosity of 3,710 centipoise (spindle # 5 at 60 fm), a pH of 7.6 and a non-volatile content of 29.4% measured at 110 ° C for 1 hour. EXAMPLE 2 Polyurethane / nanopigment dispersion This example describes the preparation of a phthalocyanine blue pigment dispersion PB 15: 3 nanoparticle size. The dispersion was prepared with the following mixture of ingredients in the indicated ratios: The ingredients were mixed using a Ross rotor / stator mixer Model # HSM-100L for 2.5 hours and then recycled using an Advantis VI 5 Drais mill containing 500 mL of a 0.3 mm Zirconox YTZ® shredder a one liter crushing chamber. The mixture was milled at 1400 m for a total time of 19 hours.

The grinding progress was monitored visually by observing the changes in the transparency of the fine films of the samples attracted downwards, on black and white Leneta paper. Charge II was added and the resulting mixture was stirred for 5 minutes at 1 ° C. Charge III was added in two aliquots for 5 minutes. The temperature of the mixture was increased to 13 ° C. The final product was a blue liquid with a Brookfield viscosity of 26 centipoise (spindle # 1 at 60 fm), at a pH of 7.2 and a non-volatile content of 30.0% measured at 110 ° C for 1 hour. EXAMPLE 3 Polyurethane / nanopigment dispersion This example describes the preparation of a di-azo PY 128 yellow pigment dispersion, nanoparticle size. The dispersion was prepared with the following mixture of ingredients in the indicated ratios: . The ingredients were mixed using a Ross rotor / stator mixer Model # HSM-100L for 5.5 hours and then recycled using an Advantis VI 5 Drais mill containing 500 mL of a 0.3 mm Zirconox YTZ® shredder a one liter crushing chamber. The mixture was milled at 1400 fm for a total time of 23 hours. The grinding progress was monitored visually by observing the changes in the transparency of the fine films of the samples attracted downwards, on black and white Leneta paper. Charge II was added and the resulting mixture was stirred for 5 minutes. Charge III was added in two aliquots for 5 minutes. The final product was a yellow liquid with a Brookfield viscosity of 53 centipoise (spindle # 1 at 60 fm), at a pH of 7.3 and a non-volatile content of 28.8% measured at 110 ° C for 1 hour. EXAMPLE 4 Preparation of an intermediate for the powder coating composition This example describes the preparation of a dry material core formula used to prepare the powder coating compositions of Examples 5 and 6. The core formula was prepared with the following ingredients in the indicated relationships: Marketed by DSM Resins Marketed by EMS Marketed by Estron Chemical Marketed by GCA Chemical 10 Marketed by Clariant 'Marketed by CIBA 12 C, marketed by Bayer Chemical' Marketed by Palmer Supplies Components 1 to 9 were pre-mixed in a Henschel mixer for 1 minute to 1,000 fm. The mixture was then extruded through a Coperion W & P co-rotating 30 mm twin screw extruder at a screw speed of 340 fm and an average torque of 30-40%. The extruder was equipped with a low pressure injection system and five independently controlled temperature zones, as described in U.S. Patent Applications 2005/0213423; 2005 / 0212159A1 and 2005/0212171 Al. The five temperature zones independently controlled were controlled at the following temperatures: Zone 1: 60 ° C; Zone 2: 120 ° C; Zone 3: 130 ° C; zone 4: 120 ° C, Zone 5: 100 ° C. The extrudate was cooled and ground in a mechanical milling system until a particle size comprised between about 28 and 30 microns was obtained. Particles exceeding this size were removed and component 10 was added. EXAMPLE 5 Preparation of a powder coating composition A powder coating composition was prepared with the following ingredients in the indicated ratios: Components 1 to 10 were pre-mixed in a Henschel mixer for 1 minute at 1,000 rpm. The mixture was then extruded through a Coperion W & P 30mm co-rotating twin screw extruder at a screw speed of 340 fm and an average torque of 30-40%. The extruder was equipped with a low pressure injection system and five independently controlled temperature zones, as described in U.S. Patent Applications 2005/0213423; 2005 / 0212159A1 and 2005/0212171 Al. The five temperature zones independently controlled were controlled at the following temperatures: Zone 1: 60 ° C; Zone 2: 120 ° C; Zone 3: 130 ° C; zone 4: 120 ° C, Zone 5: 100 ° C. The extrudate was cooled and ground in a mechanical milling system until a particle size comprised between about 28 and 30 microns was obtained. The particles exceeding this size were removed and the component 10 was added. EXAMPLE 6 Preparation of a powder coating composition A powder coating composition was prepared with the following ingredients in the indicated ratios and using the procedure and apparatus described in FIG. Example 5: EXAMPLE 7 Preparation of Powder Coating Compositions A powder coating composition was prepared from the powder coating composition intermediate of Example 4 and the polyurethane / nanopigment dispersions of Example 2. The powder coating composition was prepared using The coperion W &amp 30mm co-rotating twin screw extruder; P and the conditions described in Example 4, equipped with a low pressure injection system and five independently controlled temperature zones, as described in U.S. Patent Applications 2005/0213423; 2005 / 0212159A1 and 2005 / 0212171A1. The powder coating composition intermediate of Example 4 was fed to the extruder at a rate of 280 grams per minute and the pigment dispersions were fed to the extruder at a rate of 105 grams per minute through a low pressure injection system. . Zone 4 was equipped with a port for devolatilization for the removal of volatile vapor. The extrudate was cooled and milled in a mechanical milling system until a particle size comprised between about 28 and 30 microns was obtained. EXAMPLE 8 Preparation of a powder coating composition A powder coating composition was prepared from the powder coating composition intermediate of Example 4 and the polyurethane / nanopigment dispersion of Example 3 using the same apparatus and process conditions described in Example 7. EXAMPLE 9 Test substrates For example 9 a, a 50/50 weight percent combination of the powder coating compositions of the compositions of Examples 5 and 6 were mixed dry in a suitable container by vigorous agitation. The resulting powder coating composition was applied electrostatically to 4"x 12" electroplated or electroplated panels. The panels were cured at a suitable elevated temperature and cooled to room temperature. After a thorough inspection of the resulting coating at a distance of less than 30 cm, the coating had a "salt and pepper" appearance (mottled) where the yellow and blue tones were individually visible. For Example 9 a, a 50/50 weight percent combination of the powder coating compositions of the compositions of Examples 7 and 8 were mixed dry in a suitable container by vigorous stirring. The resulting powder coating composition was applied electrostatically to 4"x 12" electroplated or electroplated panels. The panels were cured at a suitable elevated temperature and cooled to room temperature. After a thorough inspection of the resulting coating at a distance of less than 30 cm, the coating had a homogeneous green tone. Those skilled in the art will appreciate that changes could be made to the embodiments described above without departing from the broad inventive concept of the invention. It should be understood, therefore, that this invention is not limited to the particular embodiments described but is intended to encompass the modifications that are included within the spirit and scope of the invention, as defined by the appended claims.

Claims (20)

1. CLAIMS 1. A powder coating composition suitable for producing a decorative and durable coating characterized in that it comprises a first powder coating composition having a first shade and a second powder coating composition having a second shade different from the first, wherein : (i) the first and second powder coating compositions comprise particles enclosed in a polymer, which impart color, and (ii) the powder coating composition, after direct application to at least a portion of a substrate and its curing, produces a decorative and durable coating that has a homogeneous tone different from the first and second tone.
2. 2. The powder coating composition of claim 1, characterized in that both compositions, first and second powder coating composition, comprise particles enclosed in a polymer, which impart color.
3. 3. The powder coating composition of claim 2, characterized in that the particles enclosed in a polymer, which impart color, comprise nanoparticles.
4. 4. The powder coating composition of claim 3, characterized in that the particles enclosed in a polymer, which impart color, are formed from an aqueous dispersion of particles enclosed in a polymer that impart color.
5. 5. The powder coating composition of claim 3, characterized in that the nanoparticles have a light diffusion of 10%.
6. 6. The powder coating composition of claim 3, characterized in that the nanoparticles comprise organic nanoparticles.
7. 7. The powder coating composition of claim 6, characterized in that the nanoparticles comprise organic pigments selected from perylenes, quinacridones, phthalocyanines, isoindolines, dioxazines (ie, triphenoxazoins), 1,4-diketopyrrolopyrroles, anthrapyrimidines, antantrones, flavatrones, indantrones, perinones, pyrantrones, thioindigos, 4,4'-diamino-1, r-diantraquinolyl, azo compounds, substituted derivatives thereof and mixtures thereof.
8. 8. The powder coating composition of claim 2, characterized in that the particles enclosed in a polymer, which impart color, comprise a friable polymer.
9. 9. The powder coating composition of claim 8, characterized in that the friable polymer comprises the reaction product of (i) polymerizable polyurethane polyester and, (ii) an ethylenically unsaturated monomer.
10. 10. The powder coating composition of claim 9, characterized in that the polymerizable polyurethane polyester comprises a polyurethane polyester having a terminal ethylenic unsaturation.
11. 11. The powder coating composition of claim 10, characterized in that the polyester polyurethane having a terminal ethylenic unsaturation is prepared from reagents comprising: (a) a polyisocyanate; (b) a polyester polyol; and (c) a material comprising an ethylenically unsaturated group and an active hydrogen group.
12. The powder coating composition of claim 4, characterized in that the aqueous dispersion of the particles enclosed in a polymer, which impart color, comprise a polymer that is dispersible in water.
13. 13. A powder coating composition of claim 2, characterized in that the first and second powder coating composition further comprises the same film-forming resin.
14. 14. A substrate, characterized in that it is at least partially coated with a coating deposited with the powder coating composition of claim 2.
15. 15. The substrate of claim 14, characterized in that the coating is a transparent coating.
16. 16. The multi-layer composite coating characterized in that at least one coating layer is deposited with the powder coating composition of claim 2.
17. 17. An article comprising a decorative and durable coating having a homogeneous shade deposited thereon, characterized in that (i) the decorative and durable coating is deposited directly with a powder coating composition comprising a mixture of a first powder coating composition having a first shade and a second powder coating composition having a second shade different from the first, (ii) the first powder coating composition and / or second powder coating composition comprises particles enclosed in a polymer, which impart color, and (iii) the homogeneous tone is different from the first and second tone.
18. 18. A method for preparing a decorative and durable coating having a homogeneous hue characterized in that it comprises: (a) providing a first powder coating composition having a first tone; (b) providing a second powder coating composition having a second tone different from the first; (c) mixing the first and second powder coating composition, and (d) directly applying the mixture to, at least, a portion of a substrate, wherein the first and second powder coating compositions comprise particles enclosed in a polymer, that impart color.
19. 19. Equipment characterized in that it comprises: (a) a first container comprising a powder coating composition having a first shade, and (b) a second container comprising a powder coating composition having a second shade different from that of the second coat. first, wherein (i) the first and / or second container comprises a powder coating composition comprising particles enclosed in a polymer, which impart color, and (ii) after mixing the contents of the first container with those of the second container, a powder coating composition is formed which, after its direct application on at least a portion of a substrate and its curing, produces a decorative and durable coating having a different shade of the first and second.
20. 20. A method for achieving a matching color using a powder coating composition characterized in that it comprises: (a) providing a first powder coating composition having a first shade, (b) providing a second powder coating composition having a second shade different from the first, (c) mixing the first and second powder coating composition in a proportion that produces a coating having the desired homogeneous shade when applied directly on at least a portion of a substrate and cured , wherein the first and / or second powder coating composition comprises particles enclosed in a polymer, which impart color.