Chalking-improving coating composition

Abstract

A coating composition containing a blend of AMF polymer and acrylic polymer binder exhibits improved chalking compared to a coating composition containing only acrylic polymer binder.

Description

[Technical Field]

[0001] This invention relates to a coating composition in which chalking is improved. [Background technology]

[0002] Fluoropolymer coatings, particularly those based on polyvinylidene fluoride (PVDF) resin, have a long track record of demonstrating excellent performance in outdoor applications. However, the chemical inertness of PVDF hinders adhesion to the substrate and makes pigment dispersion difficult, posing a challenge in paint design. To overcome these problems, acrylic modifiers are typically added to PVDF resin. Acrylic modifiers have traditionally been physically blended with PVDF resin to improve coating adhesion and pigment dispersibility. This physical blending yields a PVDF / acrylic mixture at a macromolecular scale. In recent years, acrylic-modified fluororesins have been developed. Acrylic-modified fluororesins ("AMF polymers") are obtained by mixing fluororesins and acrylic resins at a micromolecular scale; that is, by polymerizing acrylic monomers in the presence of a fluororesin seed. This structure is sometimes called an "interpenetration network (IPN)". AMF polymers having PVDF as a fluororesin seed are sometimes called PVDF-acrylic hybrid polymers or dispersions. These AMF polymers exhibit properties that cannot be obtained from a simple blend of fluororesin and acrylic resin. Such AMF polymers are available from Arkema under the trade name "Kynar Aquatec" (registered trademark).

[0003] These AMF polymers are used as neat polymer binders in coating compositions. Due to the high weight percentage of fluororesin in the AMF polymers, either an organic solvent or a film-forming agent is added to the composition to help form a continuous film from the discontinuous polymer particles present in the latex.

[0004] A coating is needed that is low in VOCs while exhibiting excellent chalking resistance, durt pickup resistance (DPUR), and color retention.

[0005] The applicant has found that by combining an aqueous AMF polymer with an acrylic polymer binder, properties such as chalking can be maintained even when a small amount of film-forming agent is used, provided that the total fluororesin in the coating composition is 8 to 25% by weight of the total polymer. [Overview of the project] [Problems that the invention aims to solve]

[0006] Summary of the Invention

[0007] A coating composition containing an acrylic polymer binder and an AMF polymer as binders is the same coating composition, but the composition being tested exhibits improved properties in terms of chalking, color retention, and stain resistance compared to a composition in which the acrylic polymer binder is replaced with an AMF polymer. [Means for solving the problem]

[0008] Disclosed is an aqueous coating composition, a. Based on the total polymer in the composition, 8 to 25% by weight of PVDF polymer, b. Acrylic polymer (including both the acrylic polymer binder and the acrylic polymer portion in the AMF polymer), c. Opaque pigments and, d. Film-forming agent and This is an aqueous coating composition containing [a specific ingredient]. Optionally, the aqueous coating composition contains one or more coloring pigments. Preferably, the film-forming agent is used in an amount of less than 3.9% by weight, based on the total acrylic + PVDF solids content.

[0009] Embodiments of the Invention

[0010] The first embodiment is an aqueous coating composition, Based on the total weight of the polymer (acrylic polymer binder + AMF polymer) in the composition, 8 to 25% by weight of PVDF polymer, Acrylic polymer (including both the acrylic polymer binder and the acrylic polymer portion of the AMF polymer), Opaque pigments and Water and, A film-forming agent in an amount of less than 3.9% by weight relative to the total wetted composition It is an aqueous coating composition containing PVDF, which exists in the form of an AMF polymer.

[0011] A second aspect of the present invention: The aqueous coating composition according to the first aspect, wherein the amount of PVDF in the composition is 10 to 25% by weight based on the total polymer solids content in the composition.

[0012] A third aspect of the present invention: The aqueous coating composition according to the first aspect, wherein the amount of PVDF in the composition is 10 to 20% by weight based on the total polymer solids content in the composition.

[0013] A fourth aspect of the present invention: An aqueous coating composition according to any one of aspects 1 to 3, wherein the AMF polymer comprises 30 to 70% by weight of PVDF and 70 to 30% by weight of an acrylic polymer portion.

[0014] Fifth aspect of the present invention: An aqueous coating composition according to any one of aspects 1 to 3, wherein the AMF polymer comprises 40 to 85% by weight of PVDF and 60 to 15% by weight of acrylic polymer based on the total weight of the AMF polymer.

[0015] Sixth aspect of the present invention: An aqueous coating composition according to any one of aspects 1 to 5, wherein the acrylic polymer portion of the AMF polymer contains (methyl) methacrylate monomer units.

[0016] The seventh aspect of the present invention: An aqueous coating composition according to any one of aspects 1 to 6, wherein the total acrylic polymer in the composition (meaning the acrylic polymer binder + the acrylic portion of the AMF polymer) is 75 to 92% by weight based on the total polymer in the composition.

[0017] The eighth aspect of the present invention: An aqueous coating composition according to any one of aspects 1 to 7, further comprising at least one coloring pigment.

[0018] The ninth aspect of the present invention: An aqueous coating composition according to any one of aspects 1 to 8, wherein the film-forming agent is less than 3% by weight based on the total wet composition.

[0019] [[ID=II]] The tenth aspect of the present invention: An aqueous coating composition according to any one of aspects 1 to 8, wherein the film-forming agent is less than 2.5% by weight based on the total wet composition, preferably less than 2% by weight based on the total weight of the coating composition (including water).

[0020] The eleventh aspect of the present invention: An aqueous coating composition according to any one of aspects 1 to 8, wherein the film-forming agent is less than 1.7% by weight based on the total wet composition.

[0021] The twelfth aspect of the present invention: A method of coating a substrate, comprising preparing a substrate, preparing a coating composition according to any one of the above aspects, applying the coating composition to the substrate, and drying the coating composition on the substrate to form a coating.

[0022] The thirteenth aspect of the present invention: A coating comprising a coating composition according to any one of aspects 1 to 11, wherein the coating exhibits improved chalking (ASTM 4214 - 07) compared to the same coating composition except that it does not contain an AMF polymer.

[0023] The fourteenth aspect of the present invention: A coating according to aspect 13, wherein at least four chalking values are obtained.

[0024] Fifteenth aspect of the present invention: The coating according to aspect 13 or 14, wherein the coating exhibits improved stain-attracting properties compared to a coating that does not contain the AMF polymer.

[0025] A sixteenth aspect of the present invention: The coating according to any one of aspects 13 to 15, wherein the above-mentioned coloring pigment exhibits improved color retention after 4000 hours of QUV-B weathering testing compared to a coating without AMF polymer.

[0026] Seventeenth aspect of the present invention: Delta E for 4000-hour QUV-B weathering test * (ΔE * The coating according to embodiment 16, which, when measured by the change in ), exhibits at least 10% less, and preferably 20% less, color retention compared to the same coating (in which the AMF polymer is replaced with an acrylic polymer binder in the tested formulation), except that it does not contain the AMF polymer. [Modes for carrying out the invention]

[0027] While embodiments are described clearly and concisely in this specification, it will be understood that these embodiments can be combined and separated in various ways without departing from the scope of the invention. For example, preferred features described herein will be applicable to all embodiments of the invention.

[0028] All references listed herein are incorporated herein by reference. Unless otherwise specified, all percentages in the compositions are in weight percent (wt%).

[0029] Unless otherwise specified, molecular weight is the weight-average molecular weight measured by gel permeation chromatography (GPC) using a polymethyl methacrylate standard. If the polymer contains certain types of crosslinks and GPC is not applicable due to the insoluble polymer fraction, the molecular weight of the soluble fraction / gel fraction or the soluble fraction after gel extraction is used. Crystallinity and melting temperature are measured by DSC at a heating rate of 10°C / min as described in ASTM D3418. Melt viscosity is measured at 230°C in accordance with ASTM D3835 and 100 seconds -1 It is expressed in kilopoise (kPoise).

[0030] The term "polymer" is used to mean homopolymers, copolymers, and ternary copolymers (containing three or more monomer units) unless otherwise specified. The term "polymer" is used to mean a polymer having two or more different monomer units.

[0031] The terms "PVDF" and "polyvinylidene fluoride" are used to mean both homopolymers and copolymers unless otherwise specified. The polymers may be homogeneous or heterogeneous and may have a gradient distribution of copolymer units. For the purposes of this invention, the term "PVDF" does not include the acrylic polymer portion of the AMF polymer. The terms "PVDF" or "PVDF resin" include only PVDF used as the fluororesin seed polymer portion of the AMF polymer.

[0032] Acrylic-modified fluoropolymers ("AMF polymers"), sometimes called "fluoropolymer-acrylic hybrid dispersions," refer to compositions obtained by polymerizing acrylic monomers in the presence of a fluoropolymer seed. Such AMF polymers are described in U.S. Patent No. 5,349,003, No. 6,680,357, and U.S. Patent Application Publication No. 2011 / 0118403, all of which are incorporated herein by reference.

[0033] The term "acrylic" encompasses both acrylic monomers and methacrylic monomers unless otherwise specified. An acrylic polymer means a polymer containing at least one of the acrylic monomer and / or methacrylic monomer.

[0034] The present invention provides a composition comprising an AMF polymer, wherein the fluororesin portion of the AMF polymer is 8 to 25% by weight based on the total polymer weight in the composition. The composition further comprises an acrylic polymer binder, an opacifying pigment, and a film-forming agent in an amount of less than 3.9% by weight based on the sum of the acrylic polymer binder and the AMF polymer. The composition optionally comprises at least one coloring pigment. The fluororesin of the present invention must be in the form of an AMF polymer. The advantages of the present invention can be obtained by using the AMF polymer in combination with an acrylic polymer binder.

[0035] The present invention provides a coating comprising the composition of the present invention. The dried coating can exhibit improved chalking compared to the same coating (in which the AMF polymer is replaced with the same acrylic polymer binder in the tested formulation), except that it does not contain the AMF polymer. The chalking value may be improved by at least 2 units compared to the same composition that does not contain the AMF polymer.

[0036] The present invention compares the same coating (with the AMF polymer replaced by the same acrylic polymer binder in the tested formulation) to a ΔE ratio in a 4000-hour QUV-B weathering test, except that it does not contain the AMF polymer. * When measured by change, improved color retention can be obtained by at least 10%, preferably 20%, less.

[0037] This invention reduces the amount of solvent used, resulting in a longer lifespan for the final coating with less maintenance required, thus reducing VOC emissions and extending the life of the coating.

[0038] Fluororesin portion of AMF polymer

[0039] The fluororesin used in the present invention as a seed for the acrylic polymerization process to obtain the AMF polymer is mainly formed from fluorine monomers. The term "fluorine monomer" or "fluorinated monomer" means a polymerizable alkene containing at least one fluorine atom, fluoroalkyl group, or fluoroalkoxy group bonded to the double bond of the alkene to be polymerized. The term "fluororesin" means a polymer formed by the polymerization of at least one type of fluorine monomer, and includes homopolymers, copolymers, and ternary copolymers. The fluororesin preferably contains at least 50 mol% of one or more types of fluorine monomers.

[0040] Examples of fluorine monomers useful in carrying out the present invention include vinylidene fluoride (VDF), tetrafluoroethylene (TFE), trifluoroethylene (VF3), chlorotrifluoroethylene (CTFE), hexafluoropropene (HFP), vinyl fluoride (VF), hexafluoroisobutylene, perfluorobutylethylene (PFBE), pentafluoropropene, 2,3,3,3-tetrafluoropropene (HFO-1234yf), 2-chloro-1,1-difluoroethylene (R-1122), 3,3,3-trifluoro-1-propene, 2-fluoromethyl-3,3,3-trifluoropropene, fluorinated vinyl ethers, fluorinated allyl ethers, non-fluorinated allyl ethers, fluorinated dioxole, and combinations thereof.

[0041] The fluororesin used as seed particles is preferably a vinylidene fluoride polymer obtained by emulsion polymerization. Such aqueous vinylidene fluoride polymers can be produced by conventional emulsion polymerization methods, for example, by emulsion polymerization of starting monomers in an aqueous medium in the presence of a polymerization initiator, and this process is known to those skilled in the art. Specific examples of vinylidene fluoride polymers obtained by emulsion polymerization include vinylidene fluoride homopolymers and (1) vinylidene fluoride and (2) fluorine-containing ethylenically unsaturated compounds (e.g., tetrafluoroethylene (TFE), trifluoroethylene (VF3), chlorotrifluoroethylene (CTFE), hexafluoropropene (HFP), vinyl fluoride (VF), hexafluoroisobutylene, perfluorobutylethylene (PFBE), pentafluoropropene, 2,3,3,3-tetrafluoropropene (HFO-1234yf), 2-chloro-1,1-difluoroethylene Copolymers of vinylidene fluoride include polyvinylidene fluoride homopolymers (such as R-1122, 3,3,3-trifluoro-1-propene, 2-fluoromethyl-3,3,3-trifluoropropene, fluorinated vinyl ethers, fluorinated allyl ethers, non-fluorinated allyl ethers, fluorinated dioxol, perfluoroacrylic acid, etc.), fluorine-free ethylenically unsaturated compounds (such as cyclohexyl vinyl ether and hydroxyethyl vinyl ether), and fluorine-free diene compounds (such as butadiene, isoprene, and chloroprene), all of which are copolymerizable with vinylidene fluoride. Among these, preferred are vinylidene fluoride homopolymers, vinylidene fluoride / tetrafluoroethylene copolymers, vinylidene fluoride / hexafluoropropylene copolymers, and vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymers.

[0042] Particularly preferred fluororesins are VDF homopolymers and copolymers of VDF with HFP, TFE, or CTFE, containing about 50 to about 99% by weight of VDF (preferably about 70 to about 99% by weight). Particularly preferred copolymers are copolymers of VDF and HFP, where the weight percentage of VDF in the copolymer is 50 to 99% by weight, preferably 65 to 95% by weight, based on the total monomers in the copolymer. In one preferred embodiment of the VDF / HFP copolymer, the weight percentage of HFP is 5 to 30% by weight, preferably 8 to 25% by weight, based on the total monomers in the polymer.

[0043] The fluororesin preferably has a high molecular weight. As used herein, "high molecular weight" refers to a high molecular weight as determined by ASTM standard D-3835 at 230°C and 100 seconds. -1 This refers to PVDF with a melt viscosity measured at more than 1.0 kilopoise, preferably more than 5 kilopoise, and more preferably more than 10 kilopoise.

[0044] Preferably, the fluororesin is formed by an emulsion process. Preferably, this process does not use fluorinated surfactants. The fluororesin used in the present invention does not contain fluorinated surfactants.

[0045] Acrylic portion of AMF polymer

[0046] The AMF polymer includes an acrylic portion ("acrylic polymer portion"). The acrylic polymer portion of the AMF polymer is obtained by emulsion polymerization of 5 to 95 parts by weight (relative to 100 parts by weight of vinylidene fluoride polymer) of a monomer mixture containing at least one monomer selected from alkyl acrylates having 1 to 18 carbon atoms in an alkyl group and alkyl methacrylates having 1 to 18 carbon atoms in an alkyl group, and an ethylenically unsaturated compound copolymerizable with the alkyl acrylate and alkyl methacrylate, in an aqueous medium in the presence of 100 parts by weight of vinylidene fluoride polymer particles.

[0047] Examples of alkyl acrylates having 1 to 18 carbon atoms in the alkyl group, used as one monomer to be emulsion-polymerized in the presence of vinylidene fluoride polymer particles, include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, amyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, diacetone acrylamide, and lauryl acrylate. Of these, alkyl acrylates having 1 to 8 carbon atoms in the alkyl group are preferred, and alkyl acrylates having 1 to 5 carbon atoms in the alkyl group are more preferred. Examples of alkyl methacrylates having 1 to 18 carbon atoms in the alkyl group, used as the other monomer to be emulsion-polymerized, include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, and lauryl methacrylate. Of these, alkyl methacrylates having 1 to 8 carbon atoms in the alkyl group are preferred, and alkyl methacrylates having 1 to 5 carbon atoms in the alkyl group are more preferred. These compounds (alkyl acrylates and alkyl methacrylates) can be used individually or in combination of two or more.

[0048] When using both alkyl acrylates and alkyl methacrylates, the ratio of these two esters is not important and can be adjusted as appropriate depending on the desired properties of the resulting fluorine-containing polymer.

[0049] Preferably, the acrylic polymer portion of the AMF polymer contains (methyl) methacrylate monomer units, and it is preferable that the AMF polymer contains more than 50% by weight of (methyl) methacrylate monomer units based on the total monomers in the acrylic polymer portion.

[0050] The average particle size of the AMF polymer in the latex obtained from the polymerization process ("AMF polymer latex") is 0.05 to 3 μm, preferably 0.05 to 1 μm, and more preferably 0.1 to 1 μm, and is measured by dynamic light scattering (NICOMP® 380 submicron particle sizer). The data is reported as intensity average particle size (diameter).

[0051] AMF polymer latex may optionally contain 0 to 15% by weight, preferably 0.1 to 10% by weight, of additives based on the polymer. Examples of additives include, but are not limited to, thickeners, pH adjusters, anti-settling agents, surfactants, wetting agents, fillers, defoamers, and fusible adhesion promoters.

[0052] Acrylic polymer binder (non-fluorinated)

[0053] Acrylic polymer binders are known in the art. Suitable ethylenically unsaturated (vinyl) monomers that can be polymerized into film-forming acrylic polymer binders include, but are not limited to, acrylic monomers and methacrylic monomers. As can be understood, more than one non-fluorinated acrylic polymer binder ("acrylic polymer binder") may also be used. The acrylic polymer binder of the present invention is not fluorinated.

[0054] In some embodiments, the acrylic polymer binder can be an aqueous emulsion polymerization product of an ethylenically unsaturated (meth)acrylic monomer. For example, the ethylenically unsaturated (meth)acrylic monomer can be selected from acrylic acid and methacrylic acid, alkyl acrylates and alkyl methacrylates, their hydroxyl-substituted derivatives, acrylonitrile, glycidyl acrylate and glycidyl methacrylate, or combinations thereof. More specific examples include ethyl acrylate, methyl acrylate, butyl acrylate, propyl acrylate, isobutyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, ethyl methacrylate, methyl methacrylate, butyl methacrylate, propyl methacrylate, isobutyl methacrylate, amyl methacrylate, 2-ethylhexyl methacrylate, and hexyl methacrylate.

[0055] Furthermore, up to about 10% by weight, preferably less than 5% by weight, of the (meth)acrylic monomers in the acrylic polymer binder may be substituted with one or more ethylenically unsaturated comonomers. Examples of ethylenically unsaturated comonomers include vinyl esters, particularly styrene and its derivatives, vinyl acetate, vinyl isopropyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl neononanoate, 2-ethylhexanoate, vinyl neodecanoate, vinyl neoendecanoate, vinyl neododecanoate, and mixtures thereof.

[0056] Furthermore, the acrylic polymer binder may, in its polymerized form, contain at least one ethylenically unsaturated (meth)acrylic monomer and about 0.01 to about 10% by weight of acetacetate-containing monomers based on the total weight of the acrylic polymer binder.

[0057] In some embodiments, the acrylic polymer binder may also include at least one wet-adhesion monomer in its polymerized form. The wet-adhesion monomer may be present in an amount of about 0.01 to about 10% by weight, preferably about 0.05 to about 2% by weight, based on the total weight of the acrylic polymer binder.

[0058] Examples of wet-adhesion monomers include aminoethyl acrylate and aminoethyl methacrylate, dimethylaminopropyl acrylate and dimethylaminopropyl methacrylate, 3-dimethylamino-2,2-dimethylpropyl-1-acrylate and 3-dimethylamino-2,2-dimethylpropyl-1-methacrylate, 2-N-morpholinoethyl acrylate and 2-N-morpholinoethyl methacrylate, 2-N-piperidinoethyl acrylate and 2-N-piperidinoethyl methacrylate, N-(3-dimethylaminopropyl)acrylamide and N-(3-dimethylaminopropyl)methacrylamide, N-(3-dimethylamino-2,2-dimethylpropyl)acrylamide and N-(3-dimethylamino-2,2-dimethylpropyl)methacrylate Amides, N-dimethylaminomethylacrylamide and N-dimethylaminomethylmethacrylamide, N-(4-morpholinomethyl)acrylamide and N-(4-morpholinomethyl)methacrylamide, vinylimidazole, vinylpyrrolidone, N-(2-methacryloyloxyethyl)ethyleneurea, N-(2-methacryloyloxyacetamidoethyl)-N,N'-ethyleneurea, allylalkylethyleneurea, N-methacrylamidemethylurea, N-methacryloylurea, N-[3-(1,3-diazacyclohexane)-2-one-propyl]methacrylamide, 2-(1-imidazolyl)ethyl methacrylate, 2-(1-imidazolidin-2-one)ethyl methacrylate, N-(methacrylamide)ethylurea (SIPOMER Examples include WAM II (manufactured by Rhone-Poulenc) and allylureid wet-adhesion monomers (SIPOMER WAM (manufactured by Rhone-Poulenc)).

[0059] The total acrylic polymer may be present in a coating composition containing both the acrylic polymer binder and the acrylic portion of the AMF polymer, in an amount of about 12 to about 75% by weight, based on the total weight of the acrylic polymer binder and the AMF polymer. The fluororesin (excluding the acrylic polymer portion of the AMF polymer) is present in an amount of about 8 to about 25% by weight, preferably about 50 to about 90% by weight, based on the total weight of the acrylic polymer binder and the AMF polymer.

[0060] Coloring pigments are finely ground, insoluble natural or synthetic particles used to impart color when added to paints and coating compositions. A pigment is a type of organic or inorganic substance that is insoluble in water and does not dissolve in the medium of application, but is highly dispersed to produce a color. Pigments used in coatings are well known to those skilled in the art. Examples of pigments include, but are not limited to, anatine, brookite, cadmium yellow, cadmium red, cadmium green, orange cobalt, cobalt blue, cerulean blue, aureolin, cobalt yellow, copper pigments, azurite, hampurple, hamp blue, Egyptian blue, malachite, Paris green, phthalocyanine blue BN, phthalocyanine green G, verdigris, viridian, iron oxide pigments, sanguine, caputomotum, iron oxide red, red ochre, Venetian red, Prussian blue, clay pigments, yellow ochre, raw sienna, burnt sienna, raw umber, burnt umber, marine pigments (e.g., ultramarine, ultramarine green shade), and zinc pigments (e.g., zinc white, zinc ferrite).

[0061] Opaque pigments are used to reflect light and make coatings opaque or reduce their transparency. They prevent light transmission and impart ideal brightness and whiteness to the final product. The most commonly used are titanium dioxide (TiO2), barium sulfate, zinc oxide, calcium carbonate, talc, nepheline cyanite, or combinations thereof. Titanium dioxide (TiO2) is the most common and preferred. Extenders can also be added to the formulation. Examples of suitable extenders include precipitated calcium carbonate, directly mined calcium carbonate, high-purity magnesium calcium carbonate (dolomite), high-purity calcined and ground clay (aluminosilicate), and high-purity refined magnesium silicate.

[0062] film-forming agent Film-forming agents are essential components of aqueous latex or emulsion coating compositions. When the coating is applied to a substrate and dries, the purpose of the film-forming agent in these compositions is to help separate polymer particles present in the latex form a continuous film. Furthermore, film-forming agents play a role in achieving a good balance of various coating properties.

[0063] Since it is desirable for the coating composition to have the lowest possible MFFT and high glass transition temperature, a film-forming agent is usually required in the coating composition. The film-forming solvent is an organic solvent or a plasticizer, which effectively lowers the MFFT of the polymer, satisfying the desired low MFFT during application, and then finally disperses and evaporates from the coating composition under normal temperature, humidity, and atmospheric pressure conditions, leaving a high Tg film.

[0064] Film-forming agents work by softening polymer particles and fusing them into a tough, continuous film. Common film-forming agents include ester alcohols, esters, glycol ethers, alcohols, amides, and polymers. Film-forming agents are particularly used in water-based paints such as latex paints, helping water evaporate more quickly and improving the adhesion of the paint to the surface it is applied to.

[0065] Typically, fluororesin binders in coating compositions require film-forming agents, which increase VOCs. Reducing the amount of fluororesin reduces the amount of film-forming agent needed. Combining fluororesins in the form of AMF polymers allows properties such as chalking to be maintained even with less film-forming agent.

[0066] MFFT is the minimum temperature at which a binder or composition forms a continuous film. MFFT can be measured using a gradient temperature apparatus compliant with ASTM D2354-10 (2012). An example of a suitable gradient temperature apparatus is the Rhopoint Minimum Film Forming Temperature Bar (MFFT) benchtop apparatus manufactured by Paul Gardner. Generally, the coating compositions of the present invention can be applied to a substrate at a temperature exceeding the MFFT of the composition. For example, an improved coating composition having an MFFT of 5°C can be applied to a substrate and dried at an ambient temperature of about 5°C or higher. It can be understood that both the binder and the composition may each have their own unique MFFT values. In certain embodiments, the polymer blends of the present invention may exhibit an MFFT of about 25°C or less in a given embodiment, an MFFT of about 15°C or less in a given embodiment, an MFFT of about 5°C or less in a given embodiment, or an MFFT of about 2°C or less in a given embodiment.

[0067] To improve usability, the MFFT of the coating composition can be reduced in certain embodiments by adding a suitable film-forming agent. Such film-forming agents are generally selected from slow-evaporating solvents having high boiling points, for example, around 160 to 240°C. Non-limiting examples of suitable film-forming agents include dipropylene glycol methyl ether, dipropylene glycol methyl ether acetate, dipropylene glycol n-butyl ether, ethylene glycol n-butyl ether, Texanol® ester alcohol (manufactured by Eastman Chemical), and dipropylene glycol dimethyl ether. In certain embodiments, the film-forming agent may be present in amounts of about 2% or less of the total weight (including water) of the coating composition, about 1.7% or less, or about 1.5% or less. However, as can be understood, the minimum amount of film-forming agent required to achieve a suitable MFFT may be desirable to allow for faster drying times and to ensure that the VOCs of the coating composition remain below any applicable limit.

[0068] Plasticizers can also be added to lower the MFFT. However, plasticizers can generally be distinguished from film-forming agents by their high boiling points, such as those above approximately 250°C.

[0069] The compositions of the present invention can be used as coatings on building substrates, including (but not limited to) wood, metal, plastic, and composite materials. The compositions of the present invention can be used in building paints. [Examples]

[0070] Typical clear coat composition:

[0071] A clear coat was obtained by mixing approximately 65-75 g of neutralized latex (shown in Table 1) (35 g of resin solids) with Texanol® ester alcohol (film-forming agent, 5.2 g), BYK-346 (0.5 g) silicone surfactant, and water (to a solids content of 40%). The clear coat was spread on a renetopathy chart with a 6 mil doctor blade, and the properties of the dried film were measured. ASTM D4062-11: Standard test method for paint leveling by drawdown method.

[0072] Acrylic 1 (acrylic polymer binder) is an acrylic latex with a minimum film-forming temperature (MFFT) of less than 0°C and a solids content of 55% by weight. Acrylic 2 is an acrylic latex with a minimum film-forming temperature (MFFT) of 15°C and a solids content of 58% by weight. Both Acrylic 1 and Acrylic 2 are acrylic polymer binders.

[0073] [Table 1]

[0074] Accent base composition:

[0075] Accent Pigment Grind A: The pigment grind was prepared as follows. The following ingredients were added to a metal beaker being stirred at low speed (500 rpm) with an air motor-driven cowl blade: water, dispersant (Coadis 123K), ammonium hydroxide, defoamer (TEGO® Foamex 810), surfactant (Strodex® PK0VOC), and potassium tripolyphosphate (KTPP). Titanium dioxide (TiO2) and Minex® 7 were added to this solution. The stirring speed was increased for 20 minutes (up to 3500 rpm) until the grind size reached 7+ Hegman. This preparation can be called the mill base.

[0076] [Table 2]

[0077] In a separate mixing vessel equipped with an overhead agitator and mixing paddles, the AMF polymer dispersion (44% by weight solids) was added, followed by the addition of a film-forming agent (Texanol® ester alcohol), a plasticizer (Eastman Optifilm® Enhancer 400), acrylic latex (manufactured by Arkema), and water.

[0078] In a comparative example without AMF polymer, a film-forming agent, plasticizer, and water are added to the acrylic latex. Pigment pulverized material is added, followed by a HEUR-type thickener (Coapur XS-71 diluted 50% with water), and the mixture is stirred for at least 10 minutes. COLORTREND® 888 Universal Architectural Colorant is added, starting at a ratio of 1 g of colorant per 50 g of paint base, to achieve the desired opacity.

[0079] These compositions were applied to chromate-treated aluminum panels using a 6-mil blade, and the dry film properties were measured. These panels were subjected to accelerated weathering tests based on ASTM G154-16, "Standard procedures for the operation of fluorescent ultraviolet (UV) lamp apparatus for exposure of non-metallic materials." The panels were tested using a QUV-B lamp (wavelength 313 nm) at an irradiance of 0.67 W / m². 2 An accelerated weathering test was conducted at 60°C for 8 hours, followed by a 4-hour dark condensation cycle at 50°C, for a total of 4,000 hours.

[0080] Coating compositions consisting of acrylic latex and AMF polymer dispersions were prepared according to Table 3. A film-forming agent, water, acrylic latex, and prepared accent base pigment pulverized material were added to the AMF polymer dispersion, followed by the addition of an associative thickener. [Table 3]

[0081] ΔE * A lower value indicates better color retention. The values ​​in Table 3 show that color retention improves with less than 20% fluororesin. [Table 4]

[0082] Table 4: Runs 5-8 (Table 3) were tested. The results are shown in Table 4. This series consists of accent base formulations colored with phthaloblue colorant and contains 0% or 20% fluororesin based on polymer solids. Table 4 shows that when the PVDF level is 20%, the chalking properties improve after the panel is subjected to a 4000-hour QUV-B weathering test.

[0083] choking:

[0084] Regarding the chalking results, no improvement was observed when the PVDF content was 4% or less.

[0085] A chalking test was conducted using ASTM D4214-07 "Standard Test Method for Evaluating the Degree of Chalking of Exterior Coatings," Method C (Clear Tape Method). The ASTM rank ranges from 0 to 8, with 0 being the worst (completely opaque) and 8 being the best (transparent; no trace of chalking).

[0086] [Table 5] Table 5: This series consists of accent base compositions with less than 6% PVDF relative to the polymer solids. This graph shows that at fluororesin levels of 6% by weight or less, there is no change in chalking even after 4000 hours of QUV-B weathering testing. [Table 6]

[0087] Table 6: This series consists of an accent base formulation without pigments and an accent base formulation containing a red colorant with various levels of fluororesin content. The coated substrate was exposed to a QUV-B weather resistance test for 4000 hours (the method is as described above). The chalking test was conducted using Method C (transparent tape method) of ASTM D4214-07 "Standard Test Method for Evaluating the Degree of Chalking of Exterior Paint Films". The ASTM rank is from 0 to 8, where 0 is the worst (completely opaque) and 8 is the best (transparent with no traces of chalking). This graph shows that as the level of PVDF (in the form of AMF polymer) increases, the chalking evaluation improves. This indicates that chalking is improved by adding the AMF polymer.

[0088] Stain resistance and attraction:

[0089] Regarding stain attraction resistance, advantages were confirmed by adding PVDF in the form of AMF polymer.

[0090] Stain attraction resistance is measured in a test using an aqueous slurry containing hydrophobic carbon black (Birla Raven 22) and BYK 346 as a wetting agent. After this slurry is applied to a coating dried at room temperature for 4 hours, it is gently rinsed with cold water and a paper towel. Then, using a colorimeter, the color difference ΔE * before and after the test is used to measure stain attraction resistance. (Measured according to CIE L * a * b * in 1976). The measurement of ΔE * is performed after the film has dried, comparing the soiled and unsoiled parts of the coating. A lower ΔE * indicates better stain attraction resistance (DPUR).

[0091]

Table 7

[0092] Table 7: The resistance to contamination attraction was tested for runs 1-4 in Table 1. This graph This indicates that DPUR is improved by adding PVDF, regardless of the acrylic MFFT.

[0093] Color retention:

[0094] Regarding color retention, improvement is observed even with a low PVDF content of 3.5% (depending on the pigment). PVDF exists in the form of an AMF polymer.

[0095] [Table 8]

[0096] Table 8: This table shows the color retention (ΔE) at 500-hour intervals for a total of 4000 hours of QUV-B weathering testing. * This shows the following. Three different coatings were formulated with 0%, 3.3%, or 6.8% of fluororesin derived from acrylic 1 and AMF polymer dispersions, and colored with phthaloblue colorant. ΔE * A smaller value indicates better color retention.

[0097] Coatings prepared solely by physically blending fluoropolymer seeds and acrylic latex in the letdown section result in insufficient film formation, as indicated by reduced stain-inducing properties.

[0098] [Table 9]

[0099] Table 9 shows that mechanical blending of fluororesin and acrylic polymer does not demonstrate the advantages obtained by blending AMF polymer with acrylic polymer binder.

Claims

1. A water-based coating composition, a. Based on the total weight of the polymer (acrylic polymer binder + AMF polymer) in the composition, 8 to 25% by weight of PVDF polymer, b. Acrylic polymer (including both the acrylic polymer binder and the acrylic polymer portion in the AMF polymer), c. Opaque pigments and d. Water and, e. A film-forming agent in an amount of less than 3.9% by weight based on the total wetted composition An aqueous coating composition containing PVDF, where PVDF exists in the form of an AMF polymer.

2. The aqueous coating composition according to claim 1, wherein the amount of PVDF in the composition is 10 to 25% by weight based on the total polymer in the composition.

3. The aqueous coating composition according to claim 1, wherein the amount of PVDF in the composition is 10 to 20% by weight based on the total polymer in the composition.

4. The aqueous coating composition according to any one of claims 1 to 3, wherein the AMF polymer comprises 30 to 70% by weight of PVDF and 70 to 30% by weight of an acrylic polymer portion.

5. The aqueous coating composition according to any one of claims 1 to 3, wherein the AMF polymer comprises 40 to 85% by weight of PVDF and 60 to 15% by weight of acrylic polymer based on the total weight of the AMF polymer.

6. The aqueous coating composition according to any one of claims 1 to 5, wherein the acrylic polymer portion of the AMF polymer contains (methyl) methacrylate monomer units.

7. The aqueous coating composition according to any one of claims 1 to 6, wherein the total acrylic polymer in the composition (acrylic polymer binder + acrylic polymer portion of AMF polymer) is 75 to 92% by weight based on the total polymer in the composition.

8. The aqueous coating composition according to any one of claims 1 to 7, further comprising at least one coloring pigment.

9. The aqueous coating composition according to any one of claims 1 to 8, wherein the film-forming agent is less than 3% by weight based on the total wetted composition.

10. The aqueous coating composition according to any one of claims 1 to 8, wherein the film-forming agent is less than 2.5% by weight based on the total wetted composition, preferably less than 2% by weight based on the total weight of the coating composition (including water).

11. The aqueous coating composition according to any one of claims 1 to 8, wherein the film-forming agent is less than 1.7% by weight based on the total wetted composition.

12. A method for coating a substrate, comprising: preparing a substrate; preparing a coating composition according to any one of claims 1 to 11; applying the coating composition to the substrate; and drying the coating composition on the substrate to form a coating.

13. A coating comprising the coating composition according to any one of claims 1 to 11, wherein the coating exhibits improved chalking (ASTM 4214-07) compared to the same coating composition except that the coating does not contain an AMF polymer.

14. The coating according to claim 13, which yields a choking value of at least 4.

15. The coating according to claim 13, wherein the coating exhibits improved stain resistance compared to a coating that does not contain the AMF polymer.

16. The coating according to claim 13, wherein the coloring pigment exhibits improved color retention after 4,000 hours of QUV-B weathering testing compared to a coating without AMF polymer.

17. Regarding the 4000-hour QUV-B weathering test, ΔE * The coating according to claim 16, which, when measured by the change in color retention, exhibits at least 10% less color retention, preferably 20% less, compared to the same coating (in which the AMF polymer is replaced with an acrylic polymer binder in the tested formulation), except that it does not contain the AMF polymer.

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