Thermally stable crosslinked polyvinyl fluoride coatings

Abstract

The present disclosure relates to a coating composition comprising polyvinyl fluoride (PVF), an acrylic copolymer comprising amine and / or hydroxyl functional groups, and an isocyanate or melamine crosslinker having a group reactive to amine or hydroxyl groups. Also disclosed herein are dried or cured coatings produced from the coating compositions, substrates coated with such coating compositions, the resulting dried and / or cured coated substrates, and methods of coating such substrates.

Description

Technical Field

[0001] The present disclosure relates to polyvinyl fluoride coatings capable of adhering to a wide range of primers and bare metals. Background Art

[0002] Polyvinyl fluoride (PVF) films are laminated to metals to provide aesthetic and durable protection for metals from harsh environmental conditions such as UV radiation, moisture, and corrosive environments (such as exposure to acidic and alkaline conditions). However, PVF films are available in limited colors, can only be produced in large quantities, and require adhesives to adhere to substrates. Compared to PVF films, coatings made from PVF resins retain most of the same protective and durable aesthetics, but can be processed in smaller batches, are easier to apply to substrate surfaces, and have a wider selection of aesthetic options. However, due to the inert nature of PVF polymers, PVF coatings can only adhere to limited types of primers and cannot adhere to bare metals.

[0003] Limited thermal stability is another problem of PVF polymers. In the PVF coating process, the PVF dispersion must be heated to a desired temperature to coalesce the PVF resin and evaporate the solvent to form a uniform coating. However, if the PVF resin is kept at high temperatures for a long time, the PVF polymer begins to decompose, which makes the PVF coating appear yellow. Enhanced thermal stability is desired to more easily achieve a well-coagulated coating in a variety of ovens and oven conditions.

[0004] The simplest solution for improving the adhesion of PVF coatings is to add acrylic or additional acrylic to the formulation. However, this approach may sacrifice the desirable properties of PVF coatings, such as flexibility, chemical resistance, and weather resistance.

[0005] PVF coating adhesion can also be improved by using a primer or by designing the primer. Adding a certain amount of PVF resin to the primer can improve the adhesion of the PVF top coat because it can increase the wettability of the PVF top coat on the primer and may increase mechanical interlocking and intermolecular hydrogen bonding. However, the development of PVF-containing primers can be complex and may increase costs due to the additional amount of PVF resin used.

[0006] Adhesion can also be improved by adjusting process conditions, especially not baking through the primer during the primer curing process. This approach potentially increases the diffusion of components in the primer into the topcoat, thereby increasing the adhesion of the topcoat to the primer. However, this may sacrifice the desired chemical resistance because the diffused components may change the topcoat composition.

[0007] In the publications “Tailoring Crosslink Density and Index in 2K Waterborne PVDF Coatings” (Beaugendre et al., Coatingstech 11(7), 2014) and “A New Approach to Water-based Fluoropolymer-urethane Hybrid Coatings” (Gupta et al., Proc. 2010 American Coatings Conference, Charlotte, NC, April 12-14, 2010), the authors report polyvinylidene fluoride (PVDF) / acrylic resins that can be crosslinked by isocyanates and describe that enhanced adhesion can be achieved using isocyanate crosslinking chemistry. They also describe that the cross-linkable PVDF / acrylic system can be applied and adhered to different window profile substrates such as primed aluminum, polyester fiberglass composites, and vinyl resins.

[0008] The thermal stability of thick PVF products produced by compression molding or ram extrusion processes may be improved by adding epoxides, hindered phenolic compounds, alkyl aryl phosphites, and / or mercaptoaryl imidazoles (see, e.g., U.S. Pat. No. 5,447,975). Other fluoropolymers used in coating processes (e.g., PVDF) have strong stability due to their more fluorinated polymer structure, which requires lower levels of thermal stabilizers in the formulation.

[0009] Thus, there remains a need to improve the adhesion of PVF coatings to a wide range of primer materials as well as bare metals while maintaining other favorable properties of the coatings. Summary of the invention

[0010] One aspect is a coating composition comprising polyvinyl fluoride (PVF), an acrylic copolymer comprising amine and / or hydroxyl functional groups, and an isocyanate or melamine crosslinker having reactive groups that react with amino or hydroxyl functional groups; wherein the weight ratio of the acrylic copolymer to the PVF is in the range of about 0.05:1 to about 0.25:1; and wherein the number of reactive groups in the isocyanate or melamine crosslinker relative to the total number of amine or hydroxyl functional groups in the acrylic copolymer is about 75 mol% to about 125 mol%. In some embodiments, the coating composition further comprises a pigment component, wherein the weight ratio of the pigment component to the total weight of the PVF and the acrylic copolymer in the coating composition is in the range of about 0.05:1 to about 0.25:1. In some embodiments, the coating composition further comprises an acid scavenger epoxide component, wherein the weight ratio of the acid scavenger epoxide component to the PVF is in the range of about 0.002:1 to about 0.1:1. In some embodiments, the coating composition further comprises an antioxidant component, wherein the weight ratio of the antioxidant component to the PVF is in the range of about 0.002:1 to about 0.1:1; and in some embodiments, the antioxidant component is a phosphate-based antioxidant or a phenolic antioxidant. In some embodiments, the coating composition further comprises one or more solvents, wherein the weight ratio of the solvent to the PVF is in the range of about 2:1 to about 1:1.

[0011] An additional aspect is a coating composition comprising (a) about 25 wt % to about 35 wt % of polyvinyl fluoride (PVF), (b) about 3 wt % to about 10 wt % of an acrylic copolymer containing amine and / or hydroxyl functional groups, and (c) about 75 mol % to about 120 mol % of isocyanate or melamine crosslinker reactive groups relative to the amine and / or hydroxyl functional groups of the acrylic copolymer. In some embodiments, the coating composition further includes a weight ratio of a pigment component to PVF and an acrylic copolymer in the coating composition in the range of about 0.05:1 to about 0.25:1. In some embodiments, the coating composition further includes about 0.5 wt % to about 5 wt % of an acid scavenger epoxide component. In some embodiments, the coating composition further includes about 0.5 wt % to about 5 wt % of an antioxidant component, and in some embodiments, the antioxidant component is a phosphate-based antioxidant or a phenolic antioxidant. In some embodiments, the coating composition further includes about 40 wt % to about 60 wt % of one or more solvents.

[0012] Another aspect is a substrate at least partially coated with one of the above-mentioned coating compositions. In certain embodiments, the substrate is a primer, and in certain embodiments, the primer is a polyurethane, polyester or acrylic primer. In certain embodiments, the substrate is a metal. In certain embodiments, the substrate is a cured layer of the above-mentioned coating composition. In certain embodiments, the coating composition is cured on the substrate.

[0013] Another aspect is a method of coating a substrate, the method comprising applying the above-described coating composition to at least a portion of the substrate. In some embodiments, the substrate is coil coated with the coating composition.

[0014] On the other hand is a dry-coated film composition comprising PVF, an acrylic copolymer comprising amine and / or hydroxyl functional groups, and isocyanate or melamine crosslinker reactive groups that react with amino or hydroxyl functional groups; wherein the weight ratio of the acrylic copolymer to the PVF is in the range of about 0.05:1 to about 0.25:1; and wherein the number of reactive groups in the isocyanate or melamine crosslinker is about 75 mol% to about 125 mol% relative to the total number of amine or hydroxyl functional groups in the acrylic copolymer. In some embodiments, the dry-coated film composition is coated on at least a portion of a primed substrate or a metal substrate; and in some embodiments, the primer is a polyurethane, polyester or acrylic primer. In some embodiments, the dry-coated film composition is produced by one of the above-mentioned coated substrates. In some embodiments, the dry-coated film composition is cured.

[0015] An additional aspect is a dry-coated film composition comprising (a) about 50 wt % to about 70 wt % PVF, (b) about 5 wt % to about 20 wt % of an acrylic copolymer comprising amine and / or hydroxyl functional groups, and (c) about 75 mol % to about 120 mol % of isocyanate or melamine crosslinker reactive groups relative to the amine and / or hydroxyl functional groups of the acrylic copolymer. In some embodiments, the dry-coated film composition is cured.

[0016] Other objects and advantages will become apparent to those skilled in the art upon reference to the following detailed description. DETAILED DESCRIPTION

[0017] The coating compositions of the present disclosure improve the adhesion of PVF coatings when applied to a wider range of primer materials as well as bare metal. Coatings made with PVF resins enable metal coil coaters to provide similar levels of protection against UV light and corrosive environments in a more versatile form than PVF films. Custom colors can be produced in smaller batch sizes and applied to metal coils with or without corrosion resistant primers.

[0018] The heat-stable cross-linked PVF coating formulation of the present disclosure comprises isocyanate or melamine as cross-linking agent and optionally acid scavenger epoxide component and / or antioxidant component as heat stabilizer.Isocyanate or melamine can react with amine or hydroxyl on substrate surface and amine or hydroxyl in functionalized acrylic to form covalently bonded polymer matrix.Compared with the PVF coating without cross-linking, this formation of covalent bond provides the stronger adhesion of PVF coating to substrate surface.The cross-linking in the PVF matrix also makes polymer difficult to extract with organic solvent such as methyl ethyl ketone (MEK).Optional heat stabilizer makes PVF keep stable under high curing temperature and extended curing time.

[0019] Acrylic resins are known to be soluble in PVDF, whereas they are insoluble in PVF. In this case, it is expected that the acrylic forms a separate microstructure in the PVF coating relative to the PVDF coating. The result is a well-adhered coating that retains the chemical resistance and flexibility benefits of PVF over PVDF.

[0020] definition

[0021] In this disclosure, a number of terms and abbreviations are used. The following definitions are provided.

[0022] As used herein, the terms "about" or "approximately" mean within 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1% or less of a given value or range.

[0023] The term "comprising" is intended to include embodiments encompassed by the terms "consisting essentially of and "consisting of. Similarly, the term "consisting essentially of is intended to include embodiments encompassed by the term "consisting of.

[0024] Unless explicitly indicated to the contrary, the indefinite articles "a" or "an" as used herein in the specification and claims should be understood to mean "at least one".

[0025] As used herein in the specification and claims, the phrase "and / or" should be understood to mean "either or both" of the elements so combined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Unless expressly indicated to the contrary, additional elements may optionally be present in addition to the elements specifically identified by the "and / or" clause. Thus, as a non-limiting example, when used in conjunction with open-ended language such as "comprising," a reference to "A and / or B" may refer to A without B (optionally including elements other than B) in one embodiment; to B without A (optionally including elements other than A) in another embodiment; to both A and B (optionally including other elements) in yet another embodiment; etc.

[0026] As used herein in the specification and claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" should be interpreted as inclusive, that is, including at least one of multiple elements or lists of elements, but also including more than one, and optionally, additional unlisted items. Only when explicitly indicating the opposite term such as "only one of..." or "exactly one of..." or when used in the claims, "consisting of..." will refer to including exactly one element in multiple elements or lists of elements. In general, the term "or" used herein should be interpreted as indicating exclusive alternatives (i.e., "one / kind or another / kind, but not both") only when it is preceded by the exclusive term "any one / kind", "one of...", "only one of..." or "exactly one of...". When used in the claims, "essentially consisting of..." should have its ordinary meaning as used in the field of patent law.

[0027] As used herein, the term "polyvinyl fluoride" or "PVF" includes homopolymers of vinyl fluoride, and also encompasses copolymers of vinyl fluoride and other monoethylenically unsaturated monomers copolymerizable therewith, wherein the vinyl fluoride repeating unit accounts for at least about 75% of the total weight of the copolymer. Representative monoethylenically unsaturated monomers that can be used for this purpose include vinyl esters such as acetate and stearate, acrylates and methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and isobutylene methacrylate. Other useful monomers are listed in U.S. Patent No. 3,139,470. PVF can be prepared as described in U.S. Patent No. 3,139,207, and can be manufactured in the form of oriented films as described in U.S. Patent No. 3,139,470.

[0028] PVF coating

[0029] Some embodiments relate to a coating composition comprising PVF, an acrylic copolymer comprising amine and / or hydroxyl functional groups, and an isocyanate or melamine crosslinker having reactive groups that react with the amino or hydroxyl functional groups; wherein the weight ratio of the acrylic copolymer to the PVF is in the range of about 0.05:1 to about 0.25:1; and wherein the number of reactive groups in the isocyanate or melamine crosslinker relative to the total number of amine or hydroxyl functional groups in the acrylic copolymer is about 75 mol % to about 125 mol %.

[0030] Some embodiments are directed to coating compositions comprising about 25 wt % to about 35 wt % of PVF, about 3 wt % to about 10 wt % of an acrylic copolymer comprising amine and / or hydroxyl functional groups, and about 75 mol % to about 120 mol % of isocyanate or melamine crosslinker reactive groups relative to the amine and / or hydroxyl functional groups of the acrylic copolymer.

[0031] PVF resin is generally insoluble in conventional solvents at room temperature; however, it can be dispersed in a so-called latent solvent. A dispersion of PVF powder is suspended in a latent solvent and heated to a first temperature that forms a gel and then to a higher second temperature that forms a solution. Late solvents and other techniques that can be used to dispose of PVF are discussed in U.S. Patent Nos. 2,953,818 and 3,139,470.

[0032] Such latent solvents have no appreciable solvent effect on PVF at temperatures below about 90°C, but exhibit a solvent effect on PVF at higher temperatures. Latent solvents are relatively volatile, as their boiling points are generally between about 90°C and 300°C. In some embodiments, the latent solvent is substantially removed by heating at 200°C or less for about 20 minutes. During this heat treatment, water and any volatile non-solvent are removed, and the polymer particles are subjected to the action of an increasing concentration of the latent solvent at a temperature at which the solvent is an effective solvent.

[0033] In some embodiments, the weight ratio of acrylic copolymer to PVF is in the range of about 0.05: 1 to about 0.25: 1, about 0.08: 1 to about 0.22: 1, about 0.10: 1 to about 0.20: 1, or about 0.14: 1 to about 0.16: 1. In some embodiments, the weight ratio of acrylic copolymer to PVF is about 0.05: 1, about 0.10: 1, about 0.15: 1, about 0.20: 1, or about 0.25: 1.

[0034] In some embodiments, PVF is present in the coating composition in an amount of about 25wt%, about 27wt%, about 31wt%, about 33wt%, about 28wt% to about 32wt%, or about 31wt%. In some embodiments, PVF is present in the coating composition in an amount of about 25wt%, about 27wt%, about 29wt%, about 31wt%, about 33wt%, or about 35wt%.

[0035] The acrylic copolymer used in the present coating composition is formed by the polymerization of acrylate monomers. Acrylate monomers are based on the structure of acrylic acid, which consists of vinyl and carboxylate ends. Typical acrylate monomers are acrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl methacrylate, etc. Therefore, the acrylic copolymer can include monomers of acrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, and / or butyl methacrylate.

[0036] Various hydroxyl functional monomers can be used, and in some embodiments, the present coating compositions use hydroxyalkyl esters of monocarboxylic acids (such as acrylic acid or methacrylic acid). The alkyl groups considered are primarily those containing 2-4 carbon atoms, and are illustrated as ethyl, propyl, or butyl. In some embodiments, the hydroxyl functional monomer is 2-hydroxyethyl methacrylate. Hydroxyalkyl ethers such as the hydroxyethyl ether of allyl alcohol are also useful.

[0037] In some embodiments, the hydroxyl-functional copolymer is a copolymer produced by solution copolymerization of monoethylenically unsaturated monomers (containing a desired proportion of hydroxyalkyl acrylate) in the presence of a free radical polymerization catalyst. In some embodiments, the other monomers are acrylates and methacrylates of alcohols containing 1 to 12 carbon atoms, 1 to 9 carbon atoms, 1 to 6 carbon atoms, 1 to 3 carbon atoms, or 1 to 2 carbon atoms. In some embodiments, the other monomers are at least about 50% methyl methacrylate and the balance is hydroxyethyl acrylate, and in some embodiments about 55% to about 65% methyl methacrylate, about 57% to about 63% methyl methacrylate, methyl methacrylate, or about 59% to about 61% methyl methacrylate, the balance being hydroxyethyl acrylate.

[0038] Various amine functional monomers can be used, and in some embodiments, the present coating compositions use aminoalkyl esters of monocarboxylic acids such as acrylic acid or methacrylic acid. The alkyl groups considered are primarily those containing 2-4 carbon atoms, and are illustrated by ethyl, propyl, or butyl. In some embodiments, the amino functional monomer is 2-aminoethyl methacrylate.

[0039] In some embodiments, the amine functional copolymer is a copolymer produced by solution copolymerization of monoethylenically unsaturated monomers (containing aminoalkyl acrylates in the desired proportion) in the presence of a free radical polymerization catalyst. In some embodiments, other monomers are acrylates and methacrylates with amines containing 1 to 12 carbon atoms, 2 to 10 carbon atoms, 4 to 10 carbon atoms, 6 to 10 carbon atoms, 8 to 10 carbon atoms, or 9 to 10 carbon atoms. In some embodiments, other monomers are acrylates and methacrylates with amines containing 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms. In some embodiments, other monomers are at least about 50% methyl methacrylate and the balance is aminoethyl acrylate, and in some embodiments about 55% to about 65% methyl methacrylate, about 57% to about 63% methyl methacrylate, about 58% to about 62% methyl methacrylate, or about 59% to about 61% methyl methacrylate, the balance is aminoethyl acrylate.

[0040] In some embodiments, the acrylic copolymer is present in the coating composition in an amount of about 3 wt %, about 4 wt %, about 5 wt %, about 6 wt %, about 7 wt %, about 8 wt %, about 9 wt %, or about 10 wt %.

[0041] The coating composition further comprises an isocyanate or melamine crosslinking agent in an amount sufficient to provide from about 75 mol % to about 120 mol % reactive groups relative to the amine and / or hydroxyl functional groups of the acrylic copolymer.

[0042] Non-limiting examples of isocyanate crosslinking agents include monomeric polyisocyanates, such as toluene diisocyanate, 4,4′-methylene-bis(cyclohexyl isocyanate) and isophorone diisocyanate. In certain embodiments, the isocyanate crosslinking agent is a blocked polyisocyanate, which is a polyisocyanate wherein the isocyanate group has reacted with a protective agent or a blocking agent to form a derivative, which will dissociate upon heating to remove the protective agent or blocking agent and release reactive isocyanate groups. Some examples of suitable blocking agents for polyisocyanates include aliphatic, alicyclic or aralkyl monoalcohols, hydroxylamines and ketoximes.

[0043] Non-limiting examples of melamine crosslinking agents include those sold by Cytec under the trade name Those sold, especially 301, 303, and 385 alkylated melamine-formaldehyde resins.

[0044] In some embodiments, the crosslinker is present in the coating composition in an amount relative to the amine and / or hydroxyl functional groups of the acrylic copolymer in the following range: about 75 mol% to about 120 mol%, about 80 mol% to about 115 mol%, about 85 mol% to about 110 mol%, about 90 mol% to about 105 mol%, or about 95 mol% to about 100 mol% of the crosslinker reactive groups. In some embodiments, the crosslinker is present in the coating composition in an amount relative to the amine and / or hydroxyl functional groups of the acrylic copolymer in the following amount: about 75 mol%, about 80 mol%, about 85 mol%, about 90 mol%, about 95 mol%, about 100 mol%, about 105 mol%, about 110 mol%, about 115 mol%, or about 120 mol% of the crosslinker reactive groups.

[0045] In some embodiments, the coating composition further comprises a pigment component. Suitable pigments can be inorganic or organic colored powders with any color, including but not limited to white powders of titanium oxide, white pearl powder or zinc sulfide; black powders of cobalt-copper-manganese oxide, copper-manganese oxide, copper-manganese oxide, copper-manganese-iron oxide, or iron oxide; yellow powders of titanium yellow or bismuth yellow; green powders of cobalt green or chromium oxide, or blue powders of cobalt-chromium-aluminum oxide or ultramarine. Common types of organic pigments can include azo pigments, lake pigments, phthalocyanine pigments, and quinacridone pigments. Colored powders can be used alone or in combination to achieve the desired color. The primer and the finishing layer can utilize colored powders of the same color. Alternatively, the primer and the finishing layer can utilize powders of different colors. For example, the primer can be white, gray, or light yellow, and the finishing layer can be a darker color to cover the color of the primer.

[0046] In some embodiments, the amount of pigment component present in the coating composition provides a weight ratio of the pigment component to the total amount of PVF and acrylic copolymer in the coating composition in the range of about 0.05: 1 to about 0.25: 1, about 0.07: 1 to about 0.23: 1, about 0.09: 1 to about 0.21: 1, about 0.11: 1 to about 0.19: 1, about 0.13: 1 to about 0.17: 1, or about 0.14: 1 to about 0.16: 1. In some embodiments, the pigment component is present in the coating composition in a weight ratio of the pigment component to the total amount of PVF and acrylic copolymer in the coating composition of about 0.05: 1, about 0.10: 1, about 0.15: 1, about 0.20: 1, or about 0.25: 1.

[0047] In some embodiments, the coating composition further comprises an acid scavenger epoxide component. Non-limiting examples of suitable acid scavenger epoxides include difunctional bisphenol A / epichlorohydrin derived epoxy resins and alicyclic glycidyl ethers, such as those sold by Miller-Stephenson Chemicals under the trade name and Those that are sold, especially 825, 826, 828, 830, 834, 1001F, 1002F, 1004F bifunctional bisphenol A / epichlorohydrin derived epoxy resins, and 1510 alicyclic glycidyl ether.

[0048] In some embodiments, the weight ratio of the acid scavenger epoxide component to the PVF is in the range of about 0.002: 1 to about 0.1: 1, about 0.002: 1 to about 0.08: 1, about 0.002: 1 to about 0.05: 1, about 0.002: 1 to about 0.025: 1, about 0.002: 1 to about 0.015: 1, about 0.002: 1 to about 0.01: 1, or about 0.002: 1 to about 0.005: 1. In some embodiments, the weight ratio of the acid scavenger epoxide component to the PVF is about 0.002: 1, about 0.005: 1, about 0.01: 1, about 0.015: 1, about 0.025: 1, about 0.05: 1, about 0.075: 1, or about 0.1: 1.

[0049] In some embodiments, the acid scavenger component is present in the coating composition in a range of about 0.5 wt % to about 5 wt %, about 1 wt % to about 4.5 wt %, about 1.5 wt % to about 4 wt %, about 2 wt % to about 3.5 wt %, or about 2.5 wt % to about 3 wt %. In some embodiments, the acid scavenger component is present in the coating composition in an amount of about 0.5 wt %, about 1 wt %, about 2 wt %, about 3 wt %, about 4 wt %, or about 5 wt %.

[0050] In some embodiments, the coating composition further comprises an antioxidant component. In some embodiments, the antioxidant component is a phosphate-based antioxidant or a phenolic antioxidant or a dialkyl ester of thiodipropionic acid. Non-limiting examples of suitable antioxidants include those manufactured by BASF under the trade name and Those sold, especially 1010 and 1035 phenolic antioxidants, PS800 and PS802 dialkyl thiodipropionate, and 168 Phosphate-based antioxidants. Phosphite ethers (such as those sold by SI Group under the trade name Those sold) are also suitable examples, such as TPP.

[0051] In some embodiments, the weight ratio of the antioxidant component to PVF is in the range of about 0.002: 1 to about 0.1: 1, about 0.005: 1 to about 0.08: 1, about 0.01: 1 to about 0.06: 1, about 0.015: 1 to about 0.05: 1, about 0.02: 1 to about 0.04: 1. In some embodiments, the weight ratio of the antioxidant component to PVF is about 0.002: 1, about 0.005: 1, about 0.01: 1, about 0.025: 1, about 0.05: 1, about 0.075: 1, or about 0.1: 1.

[0052] In some embodiments, the antioxidant component is present in the coating composition in a range of about 0.5 wt % to about 5 wt %, about 1 wt % to about 4.5 wt %, about 1.5 wt % to about 4 wt %, about 2 wt % to about 3.5 wt %, or about 2.5 wt % to about 3 wt %. In some embodiments, the antioxidant component is present in the coating composition in an amount of about 0.5 wt %, about 1 wt %, about 2 wt %, about 3 wt %, about 4 wt %, or about 5 wt %.

[0053] In some embodiments, the coating composition further comprises one or more solvents. Examples of suitable latent solvents may include, but are not limited to, γ-butyrolactone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, γ-valerolactone, butadiene sulfone, tetramethylene sulfone, dimethyl sulfolane, hexamethylene sulfone, diallyl sulfoxide, dicyanobutene, adiponitrile, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, isobutylene carbonate, tris(III) carbonate, 1,2-butylene ... Methylene ester, N,N-diethylformamide, N,N-dimethyl-γ-hydroxyacetamide, N,N-dimethyl γ-hydroxybutyramide, N,N-dimethylacetamide, N,N-dimethylmethoxyacetamide, N-methylacetamide, N-methylformamide, N,N-dimethylaniline, N,N-dimethylethanolamine, 2-piperidone, N-methyl-2-piperidone, 1-ethyl-2-pyrrolidone, N-isopropyl 2-pyrrolidone, S-methyl 2-pyrrolidone , β-propiolactone, δ-valerolactone, α-angelica lactone, β-angelica lactone, ε-caprolactone; α, β and γ substituted alkyl derivatives of γ-butyrolactone, γ-valerolactone, δ-valerolactone; δ substituted alkyl derivatives of δ-valerolactone; tetramethyl urea, l-nitropropane, 2-nitropropane, acetonylacetone, acetophenone, acetylacetone, cyclohexanone, diacetone alcohol, dibutyl ketone, isophorone, mesityl oxide, methyl amyl ketone, 3-methyl-cyclohexane In one or more embodiments, the latent solvent may include propylene carbonate, γ-butyrolactone, n-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, isophorone, diethyl phthalate, dimethyl phthalate, dimethyl phthalate, dimethyl ester, dimethyl benzoate, diacetate, methyl salicylate, phenyl acetate, triethyl phosphate, tri(morpholinyl)phosphine oxide, N-acetylmorpholine, N-acetylpiperidine, isoquinoline, quinoline, pyridine, xylene, tri(dimethylamido)phosphate, or a combination thereof. In one or more embodiments, the latent solvent may include propylene carbonate, γ-butyrolactone, n-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, isophorone, diethyl phthalate, dimethyl phthalate, dimethylformamide, or a combination thereof.

[0054] In one or more embodiments, the latent solvent can be mixed with another organic solvent to form a solvent system. For example, the additional organic solvent can include ethylene glycol monobutyl ether, butyl carbitol, dipropylene glycol butyl ether, propylene glycol methyl ether acetate (PMA), dibasic ester (DBE), toluene, xylene, trimethylbenzene, methyl ethyl ketone, or a combination thereof.

[0055] In some embodiments, the weight ratio of the one or more solvents to PVF is in the range of about 2: 1 to about 1: 1, about 1.95: 1 to about 1.05: 1, about 1.9: 1 to about 1.2: 1, about 1.85: 1 to about 1.3: 1, about 1.8: 1 to about 1.4: 1. In some embodiments, the weight ratio of the solvents to PVF is in the range of about 2: 1, about 1.75: 1, about 1.5: 1, about 1.25: 1, about 1.15: 1, about 1.1: 1, about 1.05: 1, or about 1: 1.

[0056] In some embodiments, one or more solvents are present in the coating composition in the following range: about 40wt% to about 60wt%, about 42wt% to about 58wt%, about 44wt% to about 56wt%, about 46wt% to about 54wt%, about 48wt% to about 52wt%, or about 49wt% to about 51wt%. In some embodiments, the solvent is present in the coating composition in an amount of about 40wt%, about 45wt%, about 50wt%, about 55wt%, or about 60wt%.

[0057] The sum of the weight percentages of the components of the PVF coating composition is 100 wt %.

[0058] Substrate

[0059] The present disclosure also relates to a substrate at least partially coated with the above-mentioned coating composition. In some embodiments, the coating composition is applied to at least about 1%, about 5%, about 10%, about 20%, about 50%, about 75%, about 90%, about 95%, about 99%, or more. In some embodiments, the coating composition is applied to the entire substrate.

[0060] Typically, as a non-limiting example, the thickness of a deposited single "layer" (whether or not identifiable as a layer) of the coating composition can range from less than 1 nm to a few or a few nanometers, for example, about 0.1 nm, 0.5 nm, 1 nm, 2 nm, 5 nm, or 10 nm, up to tens or hundreds of nanometers, for example up to or exceeding 50 nm, 100 nm, 500 nm, 600 nm, 800 nm, 900 nm, 1 μm, 5 μm, 10 μm, 20 μm, 40 μm, 50 μm or more.

[0061] The thickness of the various layers of the coating may be the same, approximately the same, or may be different.An example coating may include separate deposited layers including a clear coat on top of a tinted coat.

[0062] In some embodiments, the substrate is a primer. The primer forms a connection between the substrate pretreatment and the next coating layer. The composition of the primer will vary depending on the type of next coating layer used. Primers need to be compatible with various pretreatment and next coating systems; therefore, in some embodiments, they contain a mixture of resin systems.

[0063] In some embodiments, the primer is a polyurethane, polyester, or acrylic primer. Non-limiting examples of primers include those sold by Sherwin Williams under the trade name and Pro Those that are sold, especially PU polyurethane based paint, 871 and HB polyester primer, and ProIndustrial TM Universal acrylic primer.

[0064] In some embodiments, the substrate is a metal. The substrate can be, for example, cold rolled steel, stainless steel, metal coated steel (i.e., hot dip galvanized steel), aluminum, etc. The metal can be in the form of a coil, which in some embodiments can have a maximum width of 1.8 m, typically about 1.0 m to 1.5 m. In some embodiments, the metal substrate can have a thickness between 0.17 mm and 3.0 mm. At these thicknesses, the metal can be appropriately processed by a coil coating process (such as according to the method of the present disclosure). In some embodiments, the metal substrate has a thickness between about 0.30 mm and about 1.50 mm, because in some embodiments, this is the optimal thickness for a coil coating process.

[0065] When the PVF coating composition is applied to a metal substrate by other methods such as, for example, flexographic coating, gravure coating, curtain coating, extrusion coating or spray coating, the size of the substrate is less important. In these methods, a thin metal substrate may not be required, or if necessary, it can be reinforced during coating, such as by belts, rollers, etc. In contrast, it may be feasible to apply the PVF coating composition to a thicker metal substrate in a discontinuous process.

[0066] The metal substrate may optionally be pretreated, for example by degreasing, optionally followed by washing, rinsing, passivation and drying, and / or the pretreatment may include a chemical pretreatment based on chromium VI, chromium III or a chromium-free passivating agent. Examples of chromium-free passivating agents are titanium and / or zirconium compounds, in particular complex fluorides of these elements. These pretreatments may include any suitable conversion coating.

[0067] In some embodiments, the substrate is a cured layer of a PVF coating composition described herein.

[0068] In some embodiments, the PVF coating composition described above is cured on a substrate. In such embodiments, the coating composition of the present disclosure is at least partially applied to the surface of the substrate to be coated by any suitable procedure designed to obtain a coating of the desired thickness, and then, in some embodiments, the applied coating composition is thermally cured under controlled conditions, involving an initial heating step to evaporate the latent solvent.

[0069] In certain embodiments, the coating composition is applied to the substrate in the coil coating production line. Coil coating is a continuous and highly automated industrial process for efficiently coating metal coils. More specifically, the coil coating process is a process in which an organic or inorganic coating material is applied to a metal strip in a continuous process, the process comprising cleaning the metal surface (if necessary) and chemical pretreatment and one or both sides, single or multiple application of (liquid) paint or coating powder, which is subsequently cured or / and laminated with a permanent plastic film. The substrate is delivered from a rolling mill as a coil (that is, as a longitudinally wound strip). The standard coil weight varies, for example, 5-6 tons for aluminum and up to about 25 tons for stainless steel. The coil is positioned at the start of the production line, then unwound at a constant speed, passed through various pretreatments, coatings and curing processes, and then rewound. Two strip accumulators can be placed at the beginning and end of the production line so that the work can be carried out continuously. This allows new coils to be added (and finished coils to be removed) through metal stitching or welding processes without having to slow down or stop the production line.

[0070] Because the metal is treated in the coil coating process before it is cut and formed, the entire surface is cleaned and prepared, providing a tightly bonded finish while reducing effort, cost and chemical use. Coil coated metal, or pre-coated metal, is more durable and corrosion resistant than post-primed metal.

[0071] After the coil coating process, the coated metal can be processed (i.e., cut) into narrow coils or flat sheets. There are two types of cutting (called slitting) to produce narrow coils: log slitting and rewinding slitting. In log slitting, the coil is handled as a whole ("log"), and one or more slices are cut from the coil without the need for an unwinding / rewinding process. In rewinding slitting, the coil is unwound and passed through a machine, through a cutter or laser, and then rewound on one or more shafts to form a narrower roll. The sheet can be formed by further cutting the rolled metal strip that forms the coil or narrow coil into the desired size. Alternatively, the coated metal can be die-cut, sawed, or processed into a desired shape by other suitable means.

[0072] In some embodiments, the step of curing the at least partially or completely coated substrate forms a cured dry film having a film thickness of, for example, about 0.5 mil to about 6 mils, about 0.75 mil to about 5 mils, about 1 mil to about 4 mils, about 1.25 mil to about 3 mils, about 1.5 mil to about 2 mils. In some embodiments, the film thickness is about 0.5 mil, about 0.75 mil, about 1 mil, about 1.25 mil, about 2.5 mil, about 5 mil, or about 6 mils.

[0073] In some embodiments, the curing step may be performed at a temperature in the range of about 160° C. to about 300° C., about 180° C. to about 280° C., about 200° C. to about 260° C., or about 220° C. to about 240° C. In some embodiments, the curing step may be performed at a temperature of about 160° C., about 180° C., about 200° C., about 220° C., about 240° C., about 260° C., about 280° C., or about 300° C.

[0074] In some embodiments, the curing step can be performed for a time in the range of about 10 seconds to about 50 seconds, about 15 seconds to about 45 seconds, about 20 seconds to about 40 seconds, about 25 seconds to about 35 seconds, or about 27.5 seconds to about 32.5 seconds. In some embodiments, the curing step can be performed for a time in the range of about 10 seconds, about 15 seconds, about 20 seconds, about 25 seconds, about 30 seconds, about 35 seconds, about 40 seconds, about 45 seconds, or about 50 seconds.

[0075] The fluoropolymer dispersion composition may be applied to the substrate by any of a variety of methods including spraying, brushing, dipping, and rolling.

[0076] Also provided is a method for spraying a substrate and a substrate to be sprayed. In this spraying method, a spraying device is used to apply a fluoropolymer dispersion composition. The fluoropolymer dispersion composition is usually applied so that the wet film thickness is in the range of about 1 mil to about 4 mils, about 1.5 mils to about 3.5 mils, about 1.75 mils to about 3.25 mils, about 2 mils to about 3 mils, or about 2.25 mils to about 2.75 mils. In certain embodiments, the wet film thickness is about 1 mil, about 1.5 mils, about 2 mils, about 2.5 mils, about 3 mils, about 3.5 mils, about 4 mils.

[0077] In some embodiments, the coating is cured at a temperature in the range of about 200° C. to about 300° C., about 210° C. to about 290° C., about 220° C. to about 280° C., about 230° C. to about 270° C., or about 240° C. to about 260° C. In some embodiments, the coating is cured at a temperature of about 200° C., about 220° C., about 240° C., about 250° C., about 260° C., about 280° C., or about 300° C.

[0078] In some embodiments, the coating is cured for a time in the range of about 5 minutes to about 20 minutes, about 7.75 minutes to about 17.5 minutes, or about 10 minutes to about 15 minutes. In some embodiments, the curing step can be performed for a time of about 5 minutes, about 10 minutes, about 15 minutes, or about 20 minutes.

[0079] In some embodiments, the coating is cured to form a cured dry film having a thickness in the range of about 0.3 mil to about 2 mils, about 0.5 mil to about 1.8 mils, about 0.7 mil to about 1.6 mils, about 0.9 mil to about 1.4 mils, about 1 mil to about 1.3 mils, or about 1.1 mil to about 1.2 mils. In some embodiments, the cured dry film has a film density of about 0.3 mil, about 0.5 mil, about 0.7 mil, about 0.9 mil, about 1 mil, about 1.1 mil, about 1.3 mils, about 1.5 mils, about 1.7 mils, about 1.9 mils, or about 2 mils.

[0080] Dry-coated film composition

[0081] Some embodiments relate to a dry-coated film composition comprising PVF, an acrylic copolymer comprising amine and / or hydroxyl functional groups, and isocyanate or melamine crosslinker reactive groups that react with the amino or hydroxyl functional groups; wherein the weight ratio of the acrylic copolymer to the PVF is in the range of about 0.05:1 to about 0.25:1; and wherein the number of reactive groups in the isocyanate or melamine crosslinker relative to the total number of amine or hydroxyl functional groups in the acrylic copolymer is about 75 mol % to about 125 mol %.

[0082] Some embodiments relate to a dry-coated film composition comprising about 50 wt % to about 70 wt % of PVF, about 3 wt % to about 10 wt % of an acrylic copolymer comprising amine and / or hydroxyl functional groups, and about 75 mol % to about 120 mol % of isocyanate or melamine crosslinker reactive groups relative to the amine and / or hydroxyl functional groups of the acrylic copolymer. In the dry-coated film composition, the sum of the weight percentages of the non-volatile components of the PVF coating composition is 100 wt %.

[0083] In some embodiments, the weight ratio of acrylic copolymer to PVF is in the range of about 0.05: 1 to about 0.25: 1, about 0.075: 1 to about 0.225: 1, about 0.10: 1 to about 0.20: 1, about 0.125: 1 to about 0.175: 1, or about 0.14: 1 to about 0.16: 1. In some embodiments, the weight ratio of acrylic copolymer to PVF is about 0.05: 1, about 0.10: 1, about 0.125: 1, about 0.15: 1, about 0.175: 1, about 0.20: 1, or about 0.25: 1.

[0084] In some embodiments, PVF is present in the dry-coated film composition in a range of about 50wt% to about 70wt%, about 52wt% to about 68wt%, about 55wt% to about 65wt%, about 58wt% to about 62wt%, or about 59wt% to about 61wt%. In some embodiments, PVF is present in the dry-coated film composition in an amount of about 50wt%, about 55wt%, about 60wt%, about 65wt%, or about 70wt%.

[0085] In some embodiments, the acrylic copolymer is present in the dry-coated film composition in a range of about 5 wt % to about 20 wt %, about 7 wt % to about 18 wt %, about 10 wt % to about 15 wt %, about 11 wt % to about 14 wt %, or about 12 wt % to about 13 wt %. In some embodiments, the acrylic copolymer is present in the dry-coated film composition in an amount of about 5 wt %, about 10 wt %, about 15 wt %, or about 20 wt %.

[0086] In some embodiments, the dry-coated film composition is cured. Curing can be accomplished as discussed above.

[0087] The other components of the coating composition discussed above, i.e., isocyanate or melamine crosslinker reactive groups, pigment components, acid scavenger epoxide components, antioxidant components, and solvents may be present in the dry-coated film composition in the amounts and combinations discussed above for the coating composition. The cured composition differs from the dry-coated film composition in that after curing, the cured composition comprises a reaction product of an acrylic resin and one or more crosslinking agents. It is expected that the weight of the cured components will not differ significantly from the weight of the unreacted components. In the cured film composition, the sum of the weight percentages of the non-volatile components of the PVF coating composition is 100 wt%.

[0088] The applicant specifically combines the full content of all cited references in the present disclosure. In addition, when amount, concentration or other values ​​or parameters are given with a list of ranges or upper and lower values, this should be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or value and any lower range limit or value, regardless of whether these ranges are disclosed separately. When numerical ranges are listed herein, unless otherwise stated, the scope is intended to include its endpoints, and all integers and fractions within the scope. It is not intended that the scope of the present disclosure is limited to the specific values ​​listed when limiting the range.

[0089] Examples

[0090] The present disclosure is further defined in the following examples. It should be understood that these examples, while illustrating exemplary embodiments of the present disclosure, are given by way of illustration only.

[0091] Example 1

[0092] A series of PVF cross-linkable coating formulations were developed and tested for their adhesion to various primed or unprimed surfaces. Adhesion was measured by the cross-hatch cutter test (ASTM D3359). The test was quickly and simply performed with an inexpensive cross-hatch cutter test kit. A lattice pattern was cut into the finished film down to the substrate using a cross-hatch cutter. The test area was then brushed diagonally five times in each direction to remove any loose film finish particles. A special tape for testing adhesion was then firmly applied to the cross-hatch test area and quickly removed by pulling the tape away from the test area to show the amount of coating lifted by the test tape. The cross-hatch test area was then visually compared to the ASTM standard D3359 shown in Table 1 below.

[0093] Table 1

[0094] ASTM D3359 Classification Area removed % 5B 0％ 4B <5％ 3B 5％-15％ 2B 15％-35％ 1B 35％-65％ 0B >65％

[0095] A conventional non-crosslinked PVF coating formulation without an isocyanate crosslinker and a crosslinked PVF coating with an isocyanate were tested, with approximately the same acrylic to PVF ratio of 15%. The detailed formulations are listed in Table 2 below.

[0096] Table 2

[0097]

[0098] 1. 30% of Paraloid in the comparison example TM A solution of B-44 acrylic polymer in propylene carbonate is available from The Dow Chemical Company, Midland, MI. In Example 1, a 50% solution of Setalux DA-450-BA acrylic polymer in butyl acetate is available from Allnex Resin Company.

[0099] Both non-crosslinked PVF coatings and crosslinked PVF coatings with nearly identical formulations were applied to four different substrate surfaces (polyurethane-primed galvanized steel, polyester-primed galvanized steel, acrylic-primed galvanized steel, and unprimed galvanized steel). It was found that by introducing an isocyanate crosslinker into the PVF coating formulation, adhesion to these tested primed or unprimed substrate surfaces was improved, as shown in Table 3.

[0100] Table 3

[0101] Comparative Example 1 Example 1 Polyurethane 2B 3B Polyester 3B 5B Acrylic 5B 5B Galvanized Steel 3B 5B

[0102] Example 2

[0103] Four kinds of formulations with different acrylic and PVF ratios (10%, 15%, 20% and 25% acrylic) were further tested for adhesion to polyurethane (PU) primer, polyester (PES) primer, acrylic primer and galvanized steel (Table 4 below). For PU, PES and galvanized steel, the more acrylic resins in the coating formulation, the stronger the adhesion to both non-crosslinked and crosslinked coatings. When acrylic / PVF increased from 10% to 25%, the adhesion of non-crosslinked PVF top coating gradually increased from 0B to 5B. Crosslinked coatings follow the same trend as non-crosslinked PVF top coatings, but in each formulation with a specific acrylic and PVF ratio, compared with non-crosslinked PVF top coatings, crosslinked coatings with isocyanate crosslinkers show higher adhesion. This may be because most primers or unprimed metal surfaces have hydroxyl groups, and the isocyanate in the crosslinked coating formulation can react with these hydroxyl groups to form urethane covalent bonds. The covalent bonds formed are stronger than the mechanical interlocking and / or intermolecular hydrogen bonding formed in a non-crosslinked topcoat.

[0104] Table 4

[0105]

[0106]

[0107] 1. “-” means not measured.

[0108] Example 3

[0109] Methyl ethyl ketone (MEK) friction test (ASTM D4752) that non-crosslinkable PVF coating (preparation as shown below) is carried out proves that blue pigment is extracted, and MEK leaves white stain on coating surface.This may be because the non-crosslinked acrylic acid that is loaded with blue pigment is dissolved in MEK. Crosslinked PVF coating (preparation as shown below) is carried out identical MEK friction test, wherein blue pigment is extracted less, and white stain is not too obvious.The crosslinking of acrylic acid helps pigment to be retained in polymer network and allows lower level of polymer to be dissolved in MEK.

[0110] Table 5

[0111]

[0112] Example 4

[0113] The thermal stability of PVF coatings was studied by thermogravimetric analysis (TGA). PVF top coatings (preparations shown in Table 6 below; values ​​are given as weight percentages based on the total weight of the PVF top coating) with different amounts of different thermal stabilizers were applied to bare metal and then peeled off from the metal plate. A sample weighing about 0.5 mg was cut from the peeled PVF film and loaded into a TGA (TA Instruments, TGA550). The TGA was programmed to heat at 50°C / min and hold at 250°C for about 1h.

[0114] Table 6

[0115]

[0116] 1.“-” means not present.

[0117] The weight of the PVF sample was recorded in situ, as shown in Table 6 below. The decrease in sample weight indicates instability and decomposition of the PVF sample. Typically, at 250°C, the sample weight remains constant for a period of time (stabilization time), and then the weight decreases as the sample begins to decompose. A decrease in weight at a rate greater than 5% / min indicates the end of the stabilization period. A non-crosslinked PVF base formulation (column 2) was studied as a control, with a stabilization time of about 3 minutes. Addition of TPP at 1% and 2% did not improve stability. Addition of 1% epoxide ( Epoxy resin 828) increased the stability time to about 12 minutes. Additional epoxide (2%) had no effect on improving stability. 828 and TPP showed a synergistic effect, as the addition of 1% 828 and 1% TPP stabilized the PVF topcoat for about 15 min. The non-crosslinked PVDF topcoat as a control showed no decomposition during the 1 hour hold period at 250°C.

[0118] Table 7

[0119]

[0120] Color measurements of the coatings at the b* coordinate (blue / yellow) showed a correlation with the thermal stability time measured by TGA (Table 7). The low thermal stability samples had a positive b* value of about 3, which is consistent with their yellowish color. The yellow color may be an indication of decomposition of the PVF polymer. Add 828 helps improve thermal stability and reduces b* to negative values ​​(blue), which means less decomposition of the PVF polymer.

[0121] Example 5

[0122] Following the same procedure as Example 4, the thermal stability of cross-linked PVF top coatings (formulations shown in Table 8 below; values ​​are in grams (g)) with different thermal stabilizers was studied by TGA.

[0123] Table 8

[0124]

[0125] The cross-linked PVF topcoat with isocyanate crosslinker showed a stability time of about 5 minutes before its weight decreased (Table 9 below). 828) added to the cross-linked PVF topcoat increased the stability time to 13 min. Adding 1% TPP also extended the stability time of the cross-linked PVF topcoat to 20 min, which is different from the non-cross-linked PVF topcoat. Adding 1% The combination of 828 and 1% TPP showed a synergistic effect and had the longest stable time of 25 min.

[0126] Table 9

[0127]

[0128] Example 6

[0129] The adhesion of heat-stable cross-linked PVF to various substrates can be further enhanced by increasing the ratio of acrylic and PVF in the formulation. Utilizing the formulation shown in Table 10, according to ASTM D3359 test, heat-stable PVF coating can achieve good adhesion (5B) to acrylic primer, polyester primer, polyurethane primer and bare metal. The thermal stability of this formulation can not be directly measured by TGA, because the coating can not be peeled off from the substrate. As indirect evidence, the low b* value of this formulation confirms the good thermal stability of the sample.

[0130] Table 10

[0131]

[0132] Although certain preferred embodiments of the present invention have been described and specifically illustrated above, it is not intended to limit the present invention to such embodiments. Various modifications may be made without departing from the scope and spirit of the present invention, as set forth in the following claims.

Claims

1. A coating composition comprising: (a) Polyvinyl fluoride (PVF); (b) an acrylic copolymer containing amine and / or hydroxyl functional groups; and (c) an isocyanate or melamine crosslinking agent having reactive groups that react with amino or hydroxyl functional groups, wherein: The weight ratio of the acrylic copolymer to the PVF is in the range of 0.05:1 to 0.25:1; and The number of reactive groups in the isocyanate or melamine crosslinking agent is 75 mol % to 125 mol % relative to the total number of amine or hydroxyl functional groups in the acrylic copolymer.

2. The coating composition of claim 1, further comprising a pigment component, wherein the weight ratio of the pigment component to the total weight of the PVF and the acrylic copolymer in the coating composition is in the range of 0.05:1 to 0.25:

1.

3. The coating composition of claim 1, further comprising an acid scavenger epoxide component, wherein the weight ratio of the acid scavenger epoxide component to the PVF is in the range of 0.002:1 to 0.1:

1.

4. The coating composition of claim 1, further comprising an antioxidant component, wherein a weight ratio of the antioxidant component to the PVF is in the range of 0.002:1 to 0.1:

1.

5. The coating composition according to claim 4, wherein The antioxidant component is a phosphate-based antioxidant or a phenolic antioxidant.

6. The coating composition of claim 1, further comprising one or more solvents, wherein the weight ratio of the solvent to the PVF is in the range of 2:1 to 1:

1.

7. A substrate at least partially coated with the coating composition of claim 1.

8. The substrate according to claim 7, wherein The coated surface of the substrate is primed.

9. The substrate according to claim 8, wherein The primer is a polyurethane, polyester or acrylic primer.

10. The substrate according to claim 7, wherein The coated surface of the substrate is metal.

11. The substrate according to claim 7, wherein The coated surface of the substrate is a cured layer of the coating composition according to claim 1.

12. A dry-coated film composition comprising (a) Polyvinyl fluoride (PVF); (b) an acrylic copolymer containing amine and / or hydroxyl functional groups; and (c) isocyanate or melamine crosslinker reactive groups reactive with amino or hydroxyl functional groups, wherein: The weight ratio of the acrylic copolymer to the PVF is in the range of 0.05:1 to 0.25:1; and The number of reactive groups in the isocyanate or melamine crosslinking agent is 75 mol% to 125 mol% relative to the total number of amine or hydroxyl functional groups in the acrylic copolymer.

13. The dry-applied film composition of claim 12, which is applied to at least a portion of a primed substrate or a metal substrate.

14. The dry-coated film composition of claim 13, wherein: The primer is a polyurethane, polyester or acrylic primer.

15. The dry-coated film composition of claim 12, which is cured.

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