Zinc-containing weather-resistant powder coating primer composition

Abstract

Zinc-containing or zinc-rich powder coating compositions and methods of using the compositions, making the compositions, and applying the compositions to substrates. The coating composition may also include a film-forming resin and a cross-linking agent. A substrate may be coated by contacting at least a portion of the substrate with the coating composition and curing the composition to form a coating. The coating provides a durable weather resistant layer to the substrate and reduces the likelihood of top coat delamination.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 364,224, filed on May 5, 2022, under 35 U.S.C. §119(e), which is incorporated by reference in its entirety. Technical Field

[0003] The present disclosure relates to zinc-containing or zinc-rich powder coating primer compositions for improving weatherability of corrosion-sensitive substrates and methods for making and using the zinc-containing or zinc-rich powder coating primer compositions. Background Art

[0004] Galvanizing is a conventional method for providing durability and weatherability protection for metal substrates including steel substrates such as guardrails, transmission towers, electrical equipment, building materials, and dozens of other specialized applications, as it provides a long-term method for protecting steel from oxidation and subsequent corrosion. A 125 micron zinc coating composition is sufficient to protect exposed equipment for a period of at least 20 years. These zinc coating compositions can be applied by both hot-dip and electroplating.

[0005] Similarly, powder coatings are applied to metal substrates such as steel substrates to provide a number of beneficial properties including corrosion protection and / or decoration. Powder coatings typically comprise extruded thermoplastic or thermosetting polymers that are then ground or milled into powder. The powder is then typically electrostatically applied to the substrate and then cured with heat or UV radiation to form a coating. Zinc-containing or zinc-rich powder coatings typically include an inorganic binder that promotes uniform coating or powder coating on the surface of a given substrate. The resulting coating forms a bonded matrix that allows controlled electrogenic current flow between the iron substrate and the zinc-rich coating. Summary of the invention

[0006] The present disclosure provides zinc-containing or zinc-rich powder coating compositions and methods of using, preparing and / or applying the compositions to substrates. The coating compositions may also include a film-forming resin and a crosslinking agent. The substrate may be coated by contacting at least a portion of the substrate with the coating composition and curing the composition to form a coating. The coating provides a durable weather-resistant layer for the substrate and reduces the possibility of topcoat delamination.

[0007] In one form thereof, the present disclosure provides a powder coating composition comprising: zinc metal, the amount of the zinc metal is 20 wt.% to 50 wt.%, based on the total weight of the coating composition; and a film-forming resin, the amount of the film-forming resin is 35 wt.% to 80 wt.%, based on the total weight of the coating composition, wherein the zinc metal is present in at least two physical forms.

[0008] In its second form, the present disclosure provides a substrate coated with a powder coating composition as described herein. The coating of the substrate has a surface resistivity of 100 to 10,000,000 ohms / square and / or a scratch creep of less than 3 mm after 3000 hours of salt spray according to ASTM D 1654-08. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A schematic cross-sectional view of a powder coating stackup as described in the present disclosure is shown. DETAILED DESCRIPTION

[0010] Currently, zinc-rich epoxy powder coating primers are used in corrosive environments on steel substrates with various exterior durable powder coating top coatings. If the top coating is transparent to UV rays, these zinc-rich epoxy primers may degrade, resulting in delamination of the exterior durable powder coating top coating. Ideally, the primer is exterior durable, which would eliminate the possibility of top coating delamination. Solving this problem can eliminate or greatly minimize the risk of top coating delamination on exterior substrates exposed to weather. The present disclosure solves this problem and other needs.

[0011] like Figure 1 , a stack of powder coating layers 101 is shown on top of a substrate 106. A primer 104 may be applied to the substrate 106 by any suitable method before a top coating layer 102 is applied on top of the primer layer. The exterior durability of the primer layer 104 enhances the bond between the primer layer 104 and the top coating layer 102, greatly reducing the risk of top coating delamination.

[0012] I. Definitions:

[0013] For the purpose of the following detailed description, it should be understood that the present disclosure may take various alternative changes and step sequences, unless explicitly indicated to the contrary. In addition, except in any operating examples or where otherwise indicated, all numerals representing the amount of ingredients used in the specification and claims, for example, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters set forth in the following specification and the attached claims are approximate values ​​that can be changed according to the desired properties to be obtained by the present disclosure. At least, and not attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be interpreted in accordance with the number of reported significant digits and by applying the usual rounding techniques.

[0014]

[0013] While 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. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0015] Furthermore, it should be understood that any numerical range described herein is intended to include all subranges subsumed therein. For example, a range of "1 to 10" is intended to include all subranges between (and ratios of) the recited minimum value of 1 and the recited maximum value of 10, i.e., having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0016] In this application, unless otherwise specifically stated, the use of the singular includes the plural, and the plural encompasses the singular. In addition, in this application, unless otherwise specifically stated, the use of "or" means "and / or", even though "and / or" may be explicitly used in some cases. Further, in this application, unless otherwise specifically stated, the use of "a" or "an" means "at least one". For example, "a" polymer, "a" pigment, etc. refer to one or more items of any of these items.

[0017] "Polymer" refers to oligomers, homopolymers (eg, prepared from a single monomer species), copolymers (eg, prepared from at least two monomer species), terpolymers (eg, prepared from at least three monomer species), and grafted polymers.

[0018] "Film-forming resin" refers to a resin that, in the absence of any diluent or carrier, can form a self-supporting continuous film on at least the horizontal surface of a substrate.

[0019] "Cross-linking agent" refers to a molecule containing two or more functional groups reactive with other functional groups and capable of linking two or more monomers or polymers through chemical bonds.

[0020] II. Powder Coating Composition

[0021] The powder coating composition as described herein generally comprises a film-forming resin, a crosslinking agent and zinc metal. The powder coating composition may also comprise other additives such as flow agents, colorants, stabilizers, degassing agents, antioxidants, hardeners, waxes, etc. The coating composition may be applied and cured to form a coating on various metal and non-metal substrates to improve their weather resistance.

[0022] The coating composition can be layered under a powder topcoat, which, as used herein, refers to a topcoat embodied in the form of solid particles. The coating composition can also be layered on top of a powder undercoat, which, as used herein, refers to an undercoat embodied in the form of solid particles. The coating composition can also be layered under or on a liquid topcoat, which can be formed by melting or otherwise liquefying the powder topcoat. Multiple layers of the coating composition can be used to form a multilayer coating. The coating composition can be layered under a topcoat or a series of topcoats or on an undercoat or a series of undercoats to form a laminate.

[0023] III. Resin

[0024] The coating composition herein may include a binder or a film-forming resin in one or more components. Further, "binder" refers to a constituent material that keeps all coating composition components together when solidifying. The binder may include one or more film-forming resins that can be used to form a coating. As used herein, "film-forming resin" refers to a resin that can form a self-supporting continuous film on at least the horizontal surface of a substrate when any diluent or carrier present in the removal or composition and / or when solidifying. The terms "resin" and "polymer" are used interchangeably here. The film-forming resin can be incorporated into the components of the powder coating composition as a liquid or as a solid.

[0025] The coating compositions for the present disclosure may include any type of thermosetting powder compositions known in the art. As used herein, the term "thermosetting" refers to a composition that is irreversibly "cured" when cured or cross-linked, wherein the polymer chains of the polymer components are linked together by covalent bonds. This property is usually associated with a cross-linking reaction of the composition components, such as caused by heat or radiation. Once cured, the thermosetting resin will not melt when heated and is insoluble in solvents. The coating compositions for the present disclosure may also include thermoplastic powder compositions. As used herein, the term "thermoplastic" refers to a composition that includes polymer components that are not linked by covalent bonds and can thus flow in a liquid when heated.

[0026] Suitable film-forming resins include (meth) acrylate resins, polyurethanes, polyesters, polyamides, polyethers, polysiloxanes, epoxy resins, vinyl resins, copolymers thereof, and combinations thereof. As used herein, "(meth) acrylate" and similar terms refer to both acrylate and corresponding methacrylate. Further, the film-forming resin may have any of a variety of functional groups, including but not limited to carboxylic acid groups, amine groups, epoxy groups, hydroxyl groups, thiol groups, carbamate groups, amide groups, urea groups, isocyanate groups (including blocked isocyanate groups), and combinations thereof.

[0027] The coating composition can include any amount of film-forming resins, such as one film-forming resin or two or more film-forming resins. Based on the gross weight of the coating composition, any particular film-forming resin or any combination of film-forming resins can be present in the coating composition in an amount as low as 20wt.%, 25wt.%, 30wt.%, 35wt.%, 40wt.%, 45wt.%, 50wt.%, 55wt.%, or as high as 95wt.%, 90wt.%, 85wt.%, 80wt.%, 75wt.%, 70wt.%, 65wt.%, 60wt.%, or any range including any two of these values ​​as endpoints. Any particular film-forming resin or combination of film-forming resins can be present in the coating composition at 40 wt.% to 90 wt.%, 40 wt.% to 85 wt.%, 45 wt.% to 80 wt.%, 50 wt.% to 80 wt.%, 55 wt.% to 80 wt.%, 55 wt.% to 75 wt.%, or 60 wt.% to 70 wt.%, based on the total weight of the coating composition or based on the weight of one component of the coating composition.

[0028] IV. Cross-linking agents

[0029] The coating composition of the present disclosure may include a crosslinking agent in one or more components, which may be selected from any crosslinking agent known in the art to react with the functional groups of one or more film-forming resins used in the coating composition. As used herein, the term "crosslinking agent" refers to a molecule that includes two or more functional groups that are reactive with other functional groups and is capable of connecting two or more monomers or polymers by chemical bonds. Alternatively, the film-forming resin that forms the binder of the coating composition may have self-reactive functional groups; in this way, such resins are self-crosslinking.

[0030] Suitable crosslinking agents include phenolic resins, amino resins, epoxy resins, triglycidyl isocyanurate, β-hydroxy(alkyl)amides, alkylated urethanes, (meth)acrylates, isocyanates, blocked isocyanates, polyacids, anhydrides, organometallic acid-functional materials, polyamines, polyamides, aminoplasts, carbodiimides, oxazolines, tetrakis(methoxymethyl)glycoluril, and combinations thereof.

[0031] Any particular cross-linking agent or any combination of cross-linking agents can be present in the coating composition in an amount as low as 0.1 wt.%, 0.5 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, or as high as 50 wt.%, 45 wt.%, 40 wt.%, 35 wt.%, 30 wt.%, or any range including two of these values ​​as endpoints, based on the total weight of the coating composition. Any particular crosslinker or combination of crosslinkers can be present in an amount of 0.5 wt.% to 10 wt.%, 0.5 wt.% to 8 wt.%, 0.5 wt.% to 6 wt.%, 0.5 wt.% to 5 wt.%, 1 wt.% to 5 wt.%, 1 wt.% to 4 wt.%, or 1 wt.% to 2 wt.%, based on the total weight of the coating composition or based on the weight of one component of the coating composition.

[0032] V. Zinc

[0033] The coating compositions of the present disclosure may include zinc metal to improve its anti-corrosion and weathering properties. The zinc metal may be in several forms, such as dust, powder, granules, flakes, or combinations thereof. In the present disclosure, the term "form" refers to zinc metal in different morphologies, including but not limited to particulate or substantially cylindrical, flake or flake-like, substantially planar, and other different shapes.

[0034] As used herein, the term "zinc powder" is used interchangeably with the term "zinc dust" and refers to a powdered metallic zinc in a granular or substantially spherical form. Zinc powder is an effective and low-cost substitute for galvanized metals. Its relatively large particle size allows excellent top coating adhesion, while galvanizing generally requires pretreatments such as acid etching or cleaning primers to provide sufficient adhesion. The average particle size of the zinc powder can be as small as 0 micron, 1 micron, 2 microns, 3 microns, 4 microns, 4.5 microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns, 10 microns, 15 microns, 20 microns or as large as 50 microns, 45 microns, 40 microns, 35 microns, 30 microns, 25 microns or any range including any two of these values ​​as endpoints. The average particle size of the zinc powder can be 4.5 to 8 microns. Suitable zinc powder can be obtained from Purity Zinc Co., Zinc Corporation of America (ZCA) or US Zinc Corporation (USZinc).

[0035] As used herein, the term "zinc flakes" refers to zinc particles that are substantially planar or fibrous in shape, with an aspect ratio of width to thickness as small as 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 15:1 or as large as 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, or any range including any two of these values ​​as endpoints. The use of a combination of zinc flakes and zinc dust in a coating film provides more contact points between individual zinc flakes and zinc dust particles. This increased contact promotes sacrificial corrosion of the zinc particles, which can slow down corrosion of the underlying substrate. Benda-Lutz of Sun Chemical Group sells zinc flakes with an average particle size of about 0.9 microns wide and 10 microns long.

[0036] The coating composition may include zinc metal in several forms such as zinc dust and zinc flakes. The zinc dust may be present in the coating composition in an amount as low as 1 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, or as high as 50 wt.%, 45 wt.%, 40 wt.%, 30 wt.%, or any range including any two of these values ​​as endpoints, based on the total weight of the coating composition. The zinc flakes may be present in the coating composition in an amount as low as 1 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, or as high as 50 wt.%, 45 wt.%, 40 wt.%, 30 wt.%, or any range including any two of these values ​​as endpoints, based on the total weight of the coating composition. The total zinc content of the coating composition, which may include a combination of several forms of zinc, may be as low as 20 wt.%, 25 wt.%, 30 wt.% or as high as 50 wt.%, 45 wt.%, 40 wt.%, or any range including any two of these values ​​as endpoints, based on the total weight of the coating composition.

[0037] VI. Additives

[0038] The coating powder composition may further optionally include one or more additives known in the art. Such additives may include flow control agents, flow restrictors, dry flow agents, antioxidants, pigments, colorants, fluorescent whitening agents, extenders, surface control agents, waxes, catalysts, reaction inhibitors, corrosion inhibitors, conductivity enhancers, and combinations comprising at least one of the foregoing additives, and the like.

[0039] The outer coating can also include a colorant. As used herein, a "colorant" is any substance that imparts color and / or other opacity and / or other visual effects to the composition. The colorant can be added to the coating in any suitable form such as discrete particles, dispersions, solutions and / or flakes. A single colorant or a mixture of two or more colorants can be used in the coating of the present disclosure.

[0040] Colorants include pigments (organic or inorganic), dyes and colorants, such as those used in the paint industry and / or listed in the Dry Color Manufacturers Association (DCMA), and special effect compositions. Colorants can include finely divided solid powders that are insoluble but wettable under the conditions of use. Colorants can be organic or inorganic and can be agglomerated or non-agglomerated. Colorants can be incorporated into the coating using a grinding medium such as an acrylic grinding medium, the use of which is familiar to those skilled in the art.

[0041] The pigments and / or pigment compositions may include, but are not limited to, carbazole dioxazine crude pigments, azo, monoazo, diazo, naphthol AS, benzimidazolone, isoindolinone, isoindolinone and polycyclic phthalocyanine, quinacridone, perylene, perinone, diketopyrrolopyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavonthrone, pyranthrone, anthraquinone, dioxazines, triarylcarbonium, quinophthalone pigments, diketopyrrolopyrrole red ("DPPBO red"), titanium dioxide, carbon black, and mixtures thereof.

[0042] Pigments include, but are not limited to, solvent-based pigments and / or water-based pigments such as phthalocyanine green or blue, iron oxide, bismuth vanadate, anthraquinone and perylene, and quinacridone.

[0043] The powder coating composition may further optionally include a flow control agent, sometimes referred to as a leveling agent, which is used to promote the formation of a continuous and uniform coating. Suitable flow control agents include polyacrylates, nonionic fluorinated alkyl ester surfactants, nonionic alkyl aryl polyether alcohols, silicones, and the like, as well as combinations comprising at least one of the foregoing flow control agents. Flow control agents are typically liquids that are converted to powder form by adsorption onto a silica-based material. A preferred flow control agent is 2-ethyl acrylate polymer acrylic resin, marketed by Estron Chemical, Inc. under the trade name P-67; 2-hydroxy-1,2-diphenylethanone crystalline solid, which is believed to keep the molten coating open for a suitable time to allow degassing to occur before forming a hard cured film, sold by DSM, Inc. under the trade name Benzoin. The powder coating composition may also include a dry flow agent, such as fumed silica, such as sold by Evonik Corporation under the trade name Fumed silica for sale.

[0044] Any particular additive or any combination of additives can be present in the coating composition in an amount as low as 0.1 wt.%, 0.5 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, or as high as 20 wt.%, 19 wt.%, 18 wt.%, 17 wt.%, 16 wt.%, 15 wt.%, 14 wt.%, 13 wt.%, 12 wt.%, or any range including any two of these values ​​as endpoints, based on the total weight of the coating composition. Any additive or combination of additives can be present in an amount of 0.5 wt.% to 10 wt.%, 0.5 wt.% to 8 wt.%, 0.5 wt.% to 6 wt.%, 0.5 wt.% to 5 wt.%, 1 wt.% to 5 wt.%, 1 wt.% to 4 wt.%, or 1 wt.% to 2 wt.%, based on the total weight of the coating composition or based on the weight of one component of the coating composition.

[0045] VII. Carbon Nanotubes

[0046] The coating compositions as described herein may also include single-walled carbon nanotubes for improving the conductivity and edge corrosion performance of the coating. Single-walled carbon nanotubes are highly flexible and naturally aggregate to form ropes of elongated tubes. The formation of these ropes in the coating allows for high conductivity while maintaining low carbon nanotube loading. Preferred carbon nanotube additives are available from Tuball TM Available under the trade name MATRIX 809β.

[0047] The outer diameter of the carbon nanotube can be less than 5nm, less than 4nm, less than 3nm, less than 2nm or less than 1nm and the length can be 1 micron, 2 microns, 3 microns, 4 microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns, 10 microns, 11 microns, 12 microns, 13 microns, 14 microns, 15 microns, 16 microns, 17 microns, 18 microns, 19 microns or 20 microns. The aspect ratio of the carbon nanotube can be 100:1-10,000:1.

[0048] Any particular carbon nanotube additive or any combination of carbon nanotube additives can be present in the coating composition in an amount as low as 0.001 wt.%, 0.01 wt.%, 0.1 wt.%, 0.5 wt.%, 1 wt.%, 2 wt.%, wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, or as high as 8 wt.%, 9 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, or in any range including any two of these values ​​as endpoints, based on the total weight of the coating composition or based on the weight of one component of the coating composition. Any carbon nanotube additive or combination of carbon nanotube additives can be present in an amount of 0.5 wt.% to 10 wt.%, 0.5 wt.% to 8 wt.%, 0.5 wt.% to 6 wt.%, 0.5 wt.% to 5 wt.%, 1 wt.% to 5 wt.%, 1 wt.% to 4 wt.%, or 1 wt.% to 2 wt.%, based on the total weight of the coating composition or based on the weight of one component of the coating composition.

[0049] VIII. Substrate

[0050] The present disclosure is directed to contacting at least a portion of a substrate with a multi-component powder coating composition and curing the composition to form a coating.

[0051] According to the substrate of the present disclosure, various substrates and combinations thereof can be selected.Substrate can include carriers and automotive substrates, industrial substrates, such as ships, boats and ships and offshore facilities and ship substrates and components, storage tanks, packaging substrates, aerospace components, wooden floors and furniture, fasteners, coiled metals, heat exchangers, vents, extrusions, roofs, wheels, grates, belts, conveyors, grain or seed silos, wire meshes, bolts or nuts, screens or grids, HVAC equipment, frameworks, cans, ropes, wires, clothing, electronic components including shells and circuit boards, glass, including sports equipment, gymnasiums, buildings, bridges, containers such as food and beverage containers, etc. As used herein, "carriers" or their modifications include but are not limited to civil, commercial and military aircraft and / or land vehicles such as airplanes, helicopters, cars, motorcycles and / or trucks.The shape of substrate can be in the form of sheets, plates, bars, rods or any desired shape.

[0052] The substrate, including any of the previously described substrates, may be metallic or non-metallic. Metallic substrates include, but are not limited to, tin, steel, cold rolled steel, hot rolled steel, steel coated with zinc metal, zinc compounds, zinc alloys, electrogalvanized steel, hot dip galvanized steel, galvannealed steel, galvanized steel, steel coated with zinc alloys, stainless steel, zinc aluminum magnesium alloy coated steel, zinc aluminum alloy, aluminum, aluminum alloy, aluminum plated steel, aluminum alloy plated steel, steel coated with zinc-aluminum alloy, magnesium, magnesium alloy, nickel, nickel plating, bronze, tinplate, clad, titanium, brass, copper, silver, gold, 3-D printed metals, cast or forged metals and alloys, or combinations thereof.

[0053] Non-metallic substrates include polymers, plastics, polyesters, polyolefins, polyamides, cellulose, polystyrene, polyacrylic acid, poly(ethylene naphthalate), polypropylene, polyethylene, nylon, EVOH, polylactic acid, other "green" polymer substrates, poly(ethylene terephthalate) (PET), polycarbonates, engineered polymers such as poly(ether ether ketone) (PEEK), polycarbonate propylene butadiene styrene (PC / ABS), polyamides, wood, sheet, wood composites, particleboard, medium density fiberboard, cement, stone, glass, paper, cardboard, textiles, synthetic and natural leather, composite substrates such as fiberglass composites or carbon fiber composites, 3-D printing polymers and composites, etc.

[0054] IX. Coating method

[0055] The components of the powder coating composition can be contacted by mixing, grinding or any suitable contacting method. The components can be solids, and more specifically can be powders with an average particle size. The individual components can be contacted in any suitable ratio to form the coating composition.

[0056] Figure 1 A cross-sectional view of a substrate coated with the composition of the present application is shown. Initially, the coating composition is applied to a substrate to form a cured layer.

[0057] Prior to applying the coating composition, the substrate may be preheated to a surface temperature or bulk temperature. The substrate may be heated to a surface temperature as low as 100°F, 125°F, 150°F, 175°F, 200°F or as high as 225°F, 250°F, 275°F, 300°F, 325°F, 350°F, 375°F, 400°F, or any range including any two of these values ​​as endpoints. In other words, the substrate may be heated to a surface temperature as low as 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C or as high as 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, or any range including any two of these values ​​as endpoints. The substrate may be heated to a surface temperature of 40°C to 150°C, 50°C to 150°C, 60°C to 150°C, 70°C to 150°C, 80°C to 150°C, 90°C to 150°C, 100°C to 150°C, 110°C to 150°C, 110°C to 140°C, or 120°C to 140°C.

[0058] Once the coating composition has been applied to the substrate, the coating is cured. The curable coating composition can be cured by heating, increasing or decreasing pressure, chemically such as by moisture, or by other means such as actinic radiation and combinations thereof. Curing can include an initial curing step using radiation, followed by heating. The term "actinic radiation" refers to electromagnetic radiation that can initiate a chemical reaction. Actinic radiation includes, but is not limited to, visible light, ultraviolet (UV) rays, infrared (IR), X-rays, and gamma radiation.

[0059] The coating composition can be cured at low temperatures. The coating composition can be cured at less than 450°F, less than 425°F, less than 400°F, less than 375°F, less than 350°F, less than 325°F, less than 300°F, less than 290°F, less than 280°F, less than 275°F, less than 270°F, less than 260°F, less than 250°F, or any range including any two of these values ​​as endpoints. In other words, the coating composition can be cured at less than 240°C, less than 230°C, less than 220°C, less than 210°C, less than 200°C, less than 190°C, less than 180°C, less than 170°C, less than 160°C, less than 150°C, less than 140°C, less than 130°C, less than 120°C, or any range including any two of these values ​​as endpoints. The coating composition may be cured at a temperature of 120°C to 200°C, 120°C to 190°C, 120°C to 180°C, 120°C to 170°C, 120°C to 160°C, 120°C to 150°C, 120°C to 140°C, or 120°C to 130°C.

[0060] The curing step can be carried out any suitable time, so that coating is completely or at least partially cured. Curing time can change according to any combination of base material, coating composition, coating thickness, environmental condition, curing method or these factors. Curing time can be as short as 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes or as long as 60 minutes, 55 minutes, 50 minutes, 45 minutes, 40 minutes, 35 minutes, 30 minutes, 25 minutes, 20 minutes, 15 minutes, 12 minutes or include any two of these values ​​as any scope of endpoints. Curing time can be 1 minute to 30 minutes, 1 minute to 20 minutes, 1 minute to 15 minutes, 1 minute to 10 minutes, 1 minute to 6 minutes, 5 minutes to 15 minutes, 5 minutes to 10 minutes or 3 minutes to 9 minutes.

[0061] The thickness of the entire coating on the substrate can be as little as 0.1 mil, 0.2 mil, 0.3 mil, 0.4 mil, 0.5 mil, 0.6 mil, 0.7 mil, 0.8 mil, 0.9 mil, 1 mil, 1.5 mil, 2 mils, 2.5 mils or as much as 20 mils, 15 mils, 14 mils, 13 mils, 12 mils, 11 mils, 10 mils, 9 mils, 8 mils, 7 mils, 6 mils, 5 mils, 4 mils, 3.9 mils, 3.8 mils, 3.7 mils, 3.6 mils, 3.5 mils, 3.4 mils, 3.3 mils, 3.2 mils, 3.1 mils, 3 mils, or any range including any two of these amounts as endpoints. The thickness of the entire coating may be 1 mil to 4 mils, 1.5 mil to 2.5 mils, or 2 mil to 3 mils. The thickness may be measured according to ASTM D7091-13 test method using an Elcometer 415B Dual FNF Film Gauge.

[0062] Other application methods that can be used to apply the coating composition to the substrate include: spraying, such as by incorporating the coating composition into a liquid formulation and using a spraying device; wiping, where the coating composition is contained on and / or in a wipe and wiped manually or automatically; media spraying, where the coating composition is a solid and is sprayed onto the surface of the substrate; electrostatic application as a powder; brushing or rolling the coating composition onto the substrate, such as by incorporating the coating composition into a brushable or roller-applicable formulation (e.g., liquid or gel); vapor deposition; electrodeposition, where the formulation is a liquid and is electro-coated; or any combination thereof. The coating composition can also be applied in a mold during extrusion, calendering, or other processing of the substrate material.

[0063] The coating composition can be applied directly to the substrate without any intermediate layer between the coating composition and the substrate. The coating composition can be applied directly to the metal substrate before or after cleaning and / or treating the substrate as further described herein, but before applying any coating. The coating composition can also be applied during cleaning of components such as detergents. The coating composition can be applied to the entire surface, edges and corners of the substrate, or the coating composition can be applied to the selected portion of the substrate.

[0064] The coating composition may also form a continuous or semi-continuous layer over the substrate, or the coating composition may be applied to certain points / areas of the substrate, such as the edges and corners of the substrate. As used herein, the area referred to as an "edge" will vary based on the specific substrate, but may include, for example, the outermost side of the substrate.

[0065] The coating composition can be applied to a substrate to form a monocoat. As used herein, a "monocoat" refers to a single coating without additional coatings. Thus, the coating composition can be applied directly to a substrate and cured to form a single coating, i.e., a monocoat.

[0066] The coated substrate of the present disclosure may further include one or more additional coatings such as a second outer coating layer deposited on at least a portion of the first coating composition to form a multilayer coating, such as by applying a top coating. When forming a multilayer coating, the first coating composition may be cured before applying an additional outer coating layer, or one or more of the additional outer coating layers and the first coating composition may be cured simultaneously. It should be understood that the second outer coating layer and the additional outer coating layer may be in solid or liquid form. The coating composition may be layered under the top coating layer or a series of top coating layers to form a stack.

[0067] X. Properties of Coated Substrates

[0068] Substrates coated according to the present disclosure may have one or more improved properties and may solve one or more problems known in the coating industry. Improved properties may be observed compared to other previously known coating compositions.

[0069] The coating composition of the present invention can be cured at less than 450°F, less than 425°F, less than 400°F, less than 375°F, less than 350°F, less than 325°F, less than 300°F, less than 290°F, less than 280°F, less than 275°F, less than 270°F, less than 260°F, less than 250°F, or any range including any two of these values ​​as endpoints. In other words, the coating composition can be cured at less than 240°C, less than 230°C, less than 220°C, less than 210°C, less than 200°C, less than 190°C, less than 180°C, less than 170°C, less than 160°C, less than 150°C, less than 140°C, less than 130°C, less than 120°C, or any range including any two of these values ​​as endpoints. The coating composition may be cured at a temperature of 120°C to 200°C, 120°C to 190°C, 120°C to 180°C, 120°C to 170°C, 120°C to 160°C, 120°C to 150°C, 120°C to 140°C, or 120°C to 130°C.

[0070] The coating compositions of the present invention can be resistant to corrosion as measured by a salt spray test according to the method set forth in ASTM B117-19. The coating compositions of the present invention can exhibit an average scratch creep of less than 5 mm after being applied to a substrate for at least 100 hours, at least 200 hours, at least 300 hours, at least 400 hours, at least 500 hours, at least 600 hours, at least 700 hours, at least 800 hours, at least 1000 hours, at least 1500 hours, at least 2000 hours, at least 2500 hours, at least 3000 hours, at least 3500 hours, at least 4000 hours, at least 4500 hours, at least 5000 hours.

[0071] The coating compositions of the present invention can have a low surface resistivity as measured by ANSI / ESD STM 4.1-2017. The coating compositions of the present invention can exhibit a surface resistivity as low as 100 ohms / square, 200 ohms / square, 300 ohms / square, 400 ohms / square, 500 ohms / square, 600 ohms / square, 700 ohms / square, 800 ohms / square, 900 ohms / square, 1000 ohms / square, 2000 ohms / square, 3000 ohms / square, 4000 ohms / square, 5000 ohms / square when applied to a substrate. , 6000 ohm / square, 7000 ohm / square, 8000 ohm / square, 9000 ohm / square, 10,000 ohm / square, or as much as 50,000 ohm / square, 100,000 ohm / square, 500,000 ohm / square, 1,000,000 ohm / square, 10,000,000 ohm / square, or any range including any two of these values ​​as endpoints. The surface resistivity of the coating composition may be 100 ohm / square to 1,000,000 ohm / square, 200 ohm / square to 500,000 ohm / square, 300 ohm / square to 100,000 ohm / square, 400 ohm / square to 50,000 ohm / square, or 500 ohm / square to 10,000 ohm / square.

[0072] Examples

[0073] Example 1

[0074] Preparation of curable coating compositions

[0075] Four curable coating compositions were prepared from the components listed in Table 1.

[0076] Table 1 Mass breakdown of curable coating compositions.

[0077]

[0078]

[0079] Each of the components listed in Table 1 of Examples 1-6 was weighed in a plastic bag and mixed by shaking vigorously for 30 seconds in the same plastic bag to form a dry homogenous mixture. The mixture was melt mixed in a Theysohn 30mm twin screw extruder at a medium aggressive screw configuration and a speed of 500RPM. The first extruder zone was set at 50°C and the second zone was set at 100°C. The feed rate was such that a torque of 30-35% was observed on the device. The mixture was dripped onto a set of cooling rollers to cool the mixture and to resolidify the mixture into solid fragments. The fragments were ground using a coffee grinder and sieved through a 104 micron screen to obtain a median diameter particle size of 35-40 microns. The resulting coating composition of each of Examples 1-6 was a free-flowing solid particulate powder coating composition.

[0080] Example 2

[0081] Application and Testing of Curable Coating Compositions

[0082] The coating composition of Example 1 was subjected to a coating thickness test, a resistivity test, and a salt spray resistance test. The resulting properties are shown in Table 2 below.

[0083] Table 2 Properties of curable coating compositions

[0084]

[0085] All powder coating compositions from Examples 1-6 were applied to several pre-treated 0.032 inch x 3 inch x 6 inch cold rolled steel panels at the film thicknesses shown in Table 1 and baked at 350°F for 15 minutes. The tests described in the lower portion of Table 1 were conducted on these coated panels. Prior to the salt spray test, the top of the panels intended for the salt spray test were coated with 2 to 3 mils of white polyester TGIC powder coating.

Claims

1. A powder coating composition comprising: Zinc metal in an amount of 20 wt.% to 50 wt.%, based on the total weight of the coating composition, the zinc metal being present in at least two physical forms; and The film-forming resin is present in an amount of 35 wt. % to 80 wt. % based on the total weight of the coating composition.

2. The powder coating composition according to claim 1, wherein the film-forming resin is a saturated carboxylated polyester resin.

3. The powder coating composition according to claim 1, wherein the film-forming resin is a hydroxylated polyester resin.

4. The powder coating composition according to claim 2 or 3, wherein the composition further comprises 0.1 wt.% to 10 wt.% of an isocyanate-modified epoxy resin.

5. The powder coating composition according to claim 1, wherein the film-forming resin is an epoxy resin.

6. The powder coating composition according to any one of claims 1 to 5, wherein the composition further comprises a crosslinking agent.

7. The powder coating composition of claim 6, wherein the crosslinking agent is selected from the group consisting of beta hydroxyalkylamide, triglycidyl isocyanurate, acrylics, isocyanates, tetrakis(methoxymethyl)glycoluril, phenolic resins, dicyandiamide, carboxylated polyesters, epoxy resins, and combinations thereof.

8. The powder coating composition according to any one of claims 1 to 7, wherein the composition further comprises carbon nanotubes in an amount of 0.001 wt.% to 2 wt.%, based on the total weight of the coating composition.

9. The powder coating composition according to any one of claims 1 to 8, wherein the composition further comprises at least one of a flow agent, a degassing agent and an anti-caking agent.

10. The powder coating composition according to any one of claims 1 to 9, wherein the zinc metal comprises zinc flakes and zinc particles.

11. The powder coating primer composition according to claim 10, wherein the amount of the zinc flakes is 1 wt.% to 50 wt.% based on the total weight of the coating composition.

12. A substrate coated with the composition according to any one of claims 1 to 11.

13. The substrate according to claim 12, wherein the coating composition has at least one of the following properties: (i) a surface resistivity of 100 to 10,000,000 ohms / square as measured in accordance with ANSI / ESD STM4.1-2017; (ii) an average scratch creep of less than 3 mm after 3000 hours of salt spray according to ASTM B117-19; and (iii) Average scratch creep of less than 5 mm after 4000 hours of salt spray according to ASTM B117-19.

14. A substrate coated with a powder coating composition, the powder coating composition comprising: Zinc metal in an amount of 20 wt.% to 50 wt.%, based on the total weight of the coating composition, the zinc metal being present in at least two physical forms; and The film-forming resin is present in an amount of 35 wt. % to 80 wt. % based on the total weight of the coating composition.

15. The coated substrate according to any one of claims 13, wherein the coating comprises a film-forming resin in an amount of 35 wt.% to 80 wt.%, based on the total weight of the coating composition.

16. The coated substrate of claim 13 or claim 14, wherein the coating comprises a carboxylated polyester resin in an amount of 30 wt.% to 80 wt.%, based on the total weight of the coating composition.

17. The coated substrate according to any one of claims 1 to 15, wherein the coating comprises an epoxy resin in an amount of 30 wt.% to 80 wt.%, based on the total weight of the coating composition.

18. The coated substrate according to any one of claims 13 to 16, wherein the coating comprises 2 or more layers.

19. The coated substrate of any one of claims 13 to 17, wherein the coating has a thickness of 2 to 20 mils.

20. The coated substrate according to any one of claims 13 to 18, wherein the coating composition has at least one of the following properties: (i) a surface resistivity of 100 to 10,000,000 ohms / square as measured in accordance with ANSI / ESD STM4.1-2017; (ii) an average scratch creep of less than 3 mm after 3000 hours of salt spray according to ASTM B117-19; and (iii) Average scratch creep of less than 5 mm after 4000 hours of salt spray according to ASTM B117-19.

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