Aqueous acrylic coating composition

Abstract

Provided are an aqueous acrylic coating composition and a coated substrate, the aqueous acrylic coating composition comprising: an acrylic resin having a unit formed from at least one monomer containing a (meth) acrylic unit, wherein the acrylic resin has a plurality of reactive groups selected from hydroxyl groups, amino groups and carboxyl groups; at least one inorganic multivalent crosslinking agent reactive with the plurality of reactive groups and optionally with a surface coated by the aqueous acrylic coating composition; and water, at least a portion of the surface of the coated substrate being coated with the aqueous acrylic coating composition.

Description

Cross-references to related applications

[0001] This application relates to and claims priority to U.S. Provisional Application No. 63 / 467,709, filed May 19, 2023, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] Generally speaking, the present invention relates to an aqueous acrylic coating composition containing an inorganic multivalent crosslinking agent, and a coated substrate having the composition coated on at least a portion thereof. Background Technology

[0003] The U.S. paint and coatings industry comprises over 1,000 companies with a combined annual output exceeding $20 billion and continues to grow. Many coatings contain water-based latexes due to factors such as reduced volatile organic compound (VOC) emissions, improved ease of cleaning and application, and decreased flammability compared to solvent-based coatings. Water-based latexes contain at least a polymer dispersed in water. When a water-based latex-based coating is applied to a substrate, the water evaporates, and the remaining polymer aggregates to form a continuous cured film on the substrate. The formulation of water-based latex-based coatings can depend at least on the properties of the substrate to which the coating is applied, the humidity and temperature of the surface and surrounding environment, environmentally friendly VOC emission standards, and ultimately, cost and ease of application for the end customer.

[0004] A primer is a paint or coating product that allows a topcoat to adhere to a surface better than when applied alone. Primers are designed to adhere to a surface and form a bonding layer that is better prepared to receive paint. Unlike paint, primers are generally not intended to be used as a durable outermost finish, but can be engineered to have improved filling and bonding properties with the underlying materials. Sometimes this is achieved through chemical methods, while other methods involve controlling the physical properties of the primer, such as its porosity, tackiness, and hygroscopicity.

[0005] Unfortunately, for some substrates (including but not limited to wood, metal, plastic, masonry or cementitious substrates and composites), primers and other coatings may struggle to achieve the desired properties, such as better adhesion, reduced tack, reduced weathering, and water permeability, to name a few. Therefore, a solution is needed to provide coatings with minimal adhesion loss and excellent anti-tack, weathering, and water permeability properties, among others. Summary of the Invention

[0006] Therefore, one object of the present invention is to provide a coating system containing an inorganic crosslinking agent that can provide a potential crosslinking mechanism both within the coating and between the coating and the substrate to which it is applied.

[0007] Another object of the present invention is to provide a coating system that provides a robust passivation layer that minimizes adhesion loss, while providing one or more properties selected from excellent anti-adhesion, weathering resistance and water penetration resistance.

[0008] Another object of the present invention is to provide a coating system using an ionic crosslinking mechanism, which provides improved coating flexibility compared to a covalent crosslinking mechanism.

[0009] These and other objects of the present invention have been achieved, individually or in combination, by the discovery of a waterborne acrylic coating composition comprising:

[0010] Acrylic resin having units formed from at least one monomer containing a (meth)acrylic acid unit, wherein the acrylic resin has a plurality of reactive groups selected from hydroxyl groups, amino groups, and carboxyl groups.

[0011] At least one inorganic multivalent crosslinking agent that reacts with the plurality of reactive groups and optionally with the surface coated by the aqueous acrylic coating composition; and water; and a coated substrate having the above-described coating system applied to at least a portion of the surface of the substrate. Attached Figure Description

[0012] A more complete understanding of the invention and its many accompanying advantages will become readily apparent when considered in conjunction with the accompanying drawings, and by referring to the following detailed description, in which:

[0013] Figure 1 Photographs are provided showing the adhesion test results of coatings with different levels of inorganic multivalent crosslinking agents according to embodiments of the invention, compared to conventional acrylic primer compositions without inorganic multivalent crosslinking agents. Detailed Implementation

[0014] Embodiments of the present invention relate to a waterborne acrylic coating composition and a coated substrate coated with the coating composition onto at least a portion of the surface of a substrate. In some embodiments of the present invention, the waterborne acrylic coating composition comprises: an acrylic resin having units formed from at least one monomer containing (meth)acrylic acid units, wherein the acrylic resin has a plurality of reactive groups selected from hydroxyl groups, amino groups, and carboxyl groups; at least one inorganic multivalent crosslinking agent that reacts with the plurality of reactive groups and optionally with the surface coated by the waterborne acrylic coating composition; and water.

[0015] The range of values ​​expressed using endpoints includes all values ​​contained within that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0016] As used herein, the terms “comprising,” “having,” “with,” or variations thereof are intended to be inclusive in a manner similar to the term “comprising.” The singular forms “a,” “an,” and “the” include multiple referents unless the context clearly indicates otherwise. Furthermore, the terms “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably. Thus, for example, a coating composition containing “one” additive means that the coating composition may contain “one or more” additives. As used throughout this specification and claims, approximate language may be applied to modify quantitative expressions that can be permissibly varied without causing a change in the essential function associated with them. Therefore, values ​​modified by terms such as “about” are not limited to the specified precise values. In some cases, approximate language may correspond to the precision of the instrument used to measure the value. Moreover, unless otherwise specifically stated, the use of the terms “first,” “second,” etc., does not indicate order or importance, but rather the terms “first,” “second,” etc., are used to distinguish one element from another.

[0017] As used herein, the terms “may” and “may be” indicate a possibility of occurring within a set of conditions; possessing the specified property, characteristic, or function; and / or qualifying another verb by expressing one or more of the performance, capability, or possibility associated with a qualified verb. Thus, the use of “may” and “may be” indicates that the modified term is clearly appropriate, capable, or suitable for the indicated capability, function, or use, while taking into account that in some cases the modified term may sometimes be inappropriate, incapable, or unsuitable. For example, in some cases an event or capability may be anticipated, while in others it may not occur—this distinction is captured by the terms “may” and “may be.”

[0018] As used herein, the term "acrylic acid" includes (meth)acrylic acid, (meth)alkyl acrylate, (meth)acrylamide, (meth)acrylonitrile, and their modified forms, such as (meth)hydroxyalkyl acrylate. Throughout this document, the phrase "(meth)acryloyl" refers to both "methacryloyl" and "acryloyl". For example, (meth)acrylic acid refers to both methacrylic acid and acrylic acid, and methyl methacrylate refers to both methyl methacrylate and methyl acrylate.

[0019] The term "aqueous" composition or dispersion as used herein means particles dispersed in an aqueous medium. An "aqueous medium" as used herein refers to a continuous phase comprising at least 50% by weight of water, wherein the remaining composition of the aqueous medium comprises particles and water-miscible compounds, such as, for example, alcohols, glycols, glycol ethers, and glycol esters.

[0020] In the context of this invention, the term "aqueous" is intended to mean that the polymer component is in an aqueous medium. In some embodiments, aqueous coatings offer one or more of the following advantages:

[0021] • Low toxicity and low flammability due to low VOC levels and low HAP emissions

[0022] • Lower cost than solvent-based coatings, and in most cases requires no additives, thinners, or hardeners.

[0023] • Less paint is needed to cover the same surface area compared to using solvent-based paint solutions.

[0024] • The application equipment can be easily cleaned with water or water-based solutions, and does not require paint thinner, acetone, or methyl acetate (making it more environmentally friendly and safer for users).

[0025] Unless otherwise specified, the term “(co)polymer” as used herein includes both homopolymers (polymers containing units derived from a single monomer) and copolymers (polymers containing units derived from two or more different monomers).

[0026] As used herein, the term "weathering" refers to the formation of powdery deposits on the surface of a substrate, particularly on porous substrates and especially in alkaline substrates such as masonry or cementitious substrates, in which mineral-like components of the substrate itself readily migrate upon exposure to moisture. Weathering is essentially a phenomenon that occurs when natural salts and minerals in materials such as brick, masonry, concrete, and plaster surfaces dissolve in water present in the material. The water travels to the surface, evaporates, and the mineral deposits remain as white, powdery stains.

[0027] The term "glass transition temperature" or "Tg" used in this invention can be measured using various conventional techniques, including, for example, differential scanning calorimetry ("DSC") or calculated using the Fox equation. The DSC data and methods described herein conform to ASTM D6604-00.

[0028] The term "(meth)acrylic acid" includes either or both of acrylic acid and methacrylic acid, and the term "(meth)acrylate" includes either or both of acrylate and methacrylate.

[0029] The term "multi-stage" in the context of latex refers to a latex polymer prepared using discrete feeds of two or more monomers, or prepared using feeds with continuously varying amounts of two or more monomers. Typically, multi-stage latex will not exhibit a single Tg inflection point as measured using DSC. For example, the DSC curve of a multi-stage latex prepared using discrete feeds of two or more monomers may show two or more Tg inflection points. Conversely, the DSC curve of a multi-stage latex prepared using feeds with continuously varying amounts of two or more monomers may not show a Tg inflection point. Occasionally, when only one Tg inflection point is observed, it may be difficult to determine whether the latex represents a multi-stage latex. In such cases, a lower Tg inflection point may sometimes be detected through more careful examination, or the synthetic formulation used to prepare the latex may be examined to determine whether a multi-stage latex is intended to be produced.

[0030] The term "single-stage" in the context of latex refers to a latex polymer prepared using a single monomer or a constant charge of two or more monomers. Typically, the DSC curve of a single-stage latex prepared using a single monomer charge or a constant charge of two monomers may only show a single Tg inflection point.

[0031] The terms "preferred" and "ideally" refer to embodiments of the invention that provide certain benefits in certain circumstances. However, other embodiments may also be preferred in the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, and is not intended to exclude other embodiments from the scope of the invention.

[0032] In the context of this invention, the term "dispersion" refers to a mixture of a dispersible polymer and a carrier. The term "dispersion" includes, but is not limited to, the term "solution".

[0033] As used in this article, the term “structural unit” (also known as a polymeric unit) for naming monomers refers to the residue of the monomer after polymerization, or the monomer in its polymerized form.

[0034] The acrylic resin used in this invention can be a single-stage acrylic resin or a multi-stage acrylic resin. In some embodiments, the acrylic resin is a single-stage acrylic resin. In some embodiments, the acrylic resin is a two-stage acrylic resin.

[0035] In some embodiments of the invention, at least one monomer containing a (meth)acrylic acid unit is an alkyl (meth)acrylic acid ester. In some embodiments, at least one monomer containing a (meth)acrylic acid unit is a C1-C6 alkyl (meth)acrylic acid ester. In some embodiments, at least one monomer containing a (meth)acrylic acid unit is a member selected from the group consisting of: methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, isopropyl acrylate, isopropyl methacrylate, n-propyl acrylate, n-propyl methacrylate, n-propyl acrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, n-pentyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, isohexyl acrylate, isohexyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, cyclobutyl acrylate, cyclobutyl methacrylate, cyclopentyl acrylate, cyclopentyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate.

[0036] Not bound by theory, and as those skilled in the art will understand, this invention utilizes a potential crosslinking method by forming an organic-inorganic framework bonded to an acrylic resin. This potential crosslinking network is formed by a combination of the acrylic resin and at least one inorganic multivalent crosslinking agent. In embodiments of the invention, the acrylic resin contains a plurality of reactive groups selected from hydroxyl, amino, and carboxyl groups. At least one inorganic multivalent crosslinking agent is selected such that it reacts with the plurality of reactive groups on the acrylic resin. The resulting potential crosslinking network contributes to providing a robust coating with good passivation properties.

[0037] The waterborne acrylic coating compositions of the present invention provide good substrate adhesion, excellent anti-blocking and weathering resistance, particularly when applied to composite building materials such as wood, plastic, masonry or cementitious substrates, wood and composite building materials, and previously coated substrates. The use of ionic crosslinking via a covalent crosslinking mechanism in the waterborne acrylic resin coating compositions also provides improved flexibility. While the ionic bonds forming the crosslinks are more susceptible to moisture and pH, they provide less rigid but more dynamic bonds compared to permanently rigid covalent crosslinking systems. This improved flexibility is particularly useful for producing elastic coatings and maintains toughness, thus providing excellent adhesion and anti-blocking properties. Balancing the crosslinking density of the resin also allows for improved energy dissipation by providing resistance to brittle fracture when the sample is under load (i.e., compressive stress observed in adhesion) or peel force in adhesion tests. Materials that are too brittle (coatings) often suffer catastrophic failure because they cannot easily plastically deform to effectively dissipate energy. Tough coatings, on the other hand, dissipate energy more easily through plastic deformation and withstand higher ultimate breaking stresses. The increased crosslinking density within amorphous polymers also helps reduce free volume and chain mobility. This reduced chain mobility benefits adhesion by producing a harder / tougher coating. Weather resistance can also be improved by reducing the amount of available carboxylic acid groups throughout the polymer backbone that can act as capillaries for soluble salts. The effective blocking of these hydrophilic channels using relatively insoluble ionic crosslinking agents provides a supporting mechanism to minimize permeability generated through tortuous paths.

[0038] In some embodiments, at least one inorganic multivalent crosslinking agent is at least one member selected from the group consisting of: Zn salts, Ca salts, Mg salts, Cu salts, Al salts, Mn salts, and Fe salts. In some embodiments, at least one inorganic multivalent crosslinking agent is a member selected from Zn salts and Ca salts. In other embodiments, at least one inorganic multivalent crosslinking agent is a Zn salt, and in some embodiments, it is a complexed Zn. 2+ Salt. In other embodiments, at least one inorganic multivalent crosslinking agent is a complex salt, such as a calcium / zinc salt or other polymetallic salt.

[0039] In some embodiments of the invention, at least one inorganic multivalent crosslinking agent is present in the waterborne acrylic coating composition in an amount of 3% to 15% by weight based on the total composition. In other embodiments, at least one inorganic multivalent crosslinking agent is present in an amount of 4% to 11% by weight based on the total composition.

[0040] The ionic crosslinking in the compositions of the present invention can involve crosslinking between polymer chains within an acrylic resin through the interaction of at least one inorganic multivalent crosslinking agent with reactive groups (hydroxyl groups, amino groups, and / or carboxyl groups) positioned along the polymer chain. In some embodiments, at least one inorganic multivalent crosslinking agent further enhances adhesion to the substrate by interacting with both reactive groups on the polymer chain and reactive groups (hydroxyl groups, amino groups, and / or carboxyl groups) on the surface of the coated substrate.

[0041] In some embodiments, the coating composition may further comprise at least one additional acrylic latex, wherein the at least one additional acrylic latex comprises an acrylic copolymer. In some embodiments, the acrylic copolymer comprises at least one monomer containing a (meth)acrylic unit and an additional monomer, which may be a monomer containing a (meth)acrylic unit or an unsaturated monomer without a (meth)acrylic unit. In some embodiments, the coating composition may further comprise a polymer having a similar synergistic effect with the acrylic resin polymer, such as, for example, an epoxy resin or a urethane. The coating composition may also typically comprise many other additives and components, such as conventional ones or other additives and components suitable for the coating composition. Examples of suitable additives may include, but are not limited to, any one or more of the following: neutralizers, waxes, defoamers, fillers, dyes, dispersants, surfactants, extenders, adhesion promoters, wetting agents, rheology modifiers, leveling agents, antiflocculators, antiblocking agents, antimicrobial agents (such as fungicides, algaecides, and bactericides), other preservatives, thickeners, thixotropic agents, desiccants, antisettling agents, rust inhibitors, leveling agents, pigments, hardeners, and combinations thereof. Suitable examples of various optional components are set forth herein and also disclosed in U.S. Patent 8,993,110, the relevant portions of which are incorporated herein by reference.

[0042] The amount and quantity of coating components in a coating composition can depend on the desired properties of the coating composition and the cured coating formed therefrom. Desired properties can depend on the material of the substrate, the intended use of the substrate, the surrounding environment during the application of the coating composition, and the environment to which the coated substrate will be exposed. In some embodiments, the coating components can be tailored for aesthetic purposes. For example, the coating composition can be formulated to achieve the desired finish and color of the cured coating formed therefrom. For example, the coating compositions disclosed herein can coalesce on a warm substrate without a coalescing agent to form, for example, a flat, satin, or eggshell-like cured coating. A glossy finish can also be achieved, but it is generally not a preferred finish when used as a primer or topcoat.

[0043] Any suitable rheology modifier may be incorporated into the coating composition. Examples of polyurethane rheology modifiers may include, but are not limited to, nonionic, solvent-free, hydrophobically modified ethylene oxide urethane (HEUR) rheology modifiers and nonionic urethane rheology modifiers.

[0044] The coating composition may contain any suitable surfactant. Examples of phosphate surfactants include, but are not limited to, phosphate esters such as methyl phosphate, 2-ethylhexyl phosphate, decanol ethoxylated phosphate, lauryl ethoxylated phosphate, n-octyl phosphate, nonylphenol ethoxylated phosphate, octylphenol ethoxylated phosphate, styryl phenol ethoxylated phosphate, tridecyl alcohol ethoxylated phosphate, etc.

[0045] The coating composition may contain one or more waxes. These waxes can be any desired wax, depending on the desired properties. In some embodiments, the waxes include, but are not limited to, polyethylene waxes, oxidized polyolefin waxes, amide-modified polyolefin waxes, paraffin waxes, and other hydrocarbon waxes. Such waxes may also provide improved weathering properties of the coated substrate, particularly in applications to masonry or cementitious substrates.

[0046] Any suitable dispersant (such as any one or more of anionic, cationic, amphoteric, or nonionic dispersants) may be used in the coating composition. Examples of dispersants may include, but are not limited to, 2-amino-2-methyl-1-propanol, pyrophosphates (such as tetrapotassium pyrophosphate and tetrasodium pyrophosphate), tripolyphosphates (such as potassium tripolyphosphate and sodium tripolyphosphate), etc. Any suitable wetting agent may be used, such as any one or more of anionic, cationic, amphoteric, or nonionic wetting agents. Any suitable antiflocculating agent may be used, such as potassium sodium tripolyphosphate.

[0047] If desired, the coating composition may contain one or more fillers or extenders. Examples of fillers include, but are not limited to, sodium potassium aluminum silicate and calcium carbonate. When used, such fillers may be used in any amount required.

[0048] Useful antimicrobial additives include phosphates, zeolites, hydroxyapatite, organic acids, phenols, alcohols, quaternary ammonium compounds, and additives containing metal ions (such as silver, zinc, and copper ions).

[0049] The coating composition may contain any suitable desiccant. Examples of desiccants include, but are not limited to, metal-based catalysts, such as iron complex catalysts, cobalt-free and metal-based catalysts, and zirconium-based catalysts. Preferably, the suitable desiccant is VOC-free.

[0050] One or more types of pigments may be included in a coating composition via any suitable technique, such as by adding the original pigment or pigment carrier during the manufacture of the composition, or by dripping the pigment at the point of sale. Examples of pigments may include, but are not limited to, azo pigments, anazurite, aluminum silicate, potassium aluminum silicate, aluminum paste, anthraquinone pigments, antimony oxide, barium metaborate, barium sulfate, cadmium sulfide, cadmium selenide, calcium carbonate, calcium metaborate, calcium metasilicate, carbon black, chromium oxide, clay, copper oxide, copper oxychloride, dioxazine pigments, feldspar, fast yellow azo pigments (some of which are listed above), benzimidazole, and iron oxides (such as yellow and red iron oxides). The pigments used include isoindoline pigments, kaolinite, lithopone, magnesium silicate, metal flakes, mica, naphthol pigments (such as naphthol red), nitrosyl pigments, nepheline syenite, perylene ketone pigments, perylene pigments, polycyclic pigments, pyrrolopyrrole pigments, phthalocyanines (such as phthalocyanine copper blue and phthalocyanine copper green), quinacridones (such as quinacridone violet), quinacridone pigments, silicates, sulfides, talc, titanium dioxide, ultramarine, zinc chromate, zinc oxide, and zinc phosphate. Additionally, pearlescent agents, optical brighteners, and UV stabilizers can be added to the coating composition. Titanium dioxide is a preferred pigment / brightener.

[0051] The waterborne acrylic resin of the present invention can be prepared by any desired polymerization method, preferably by free radical polymerization in an aqueous medium. In some embodiments, the acrylic resin is prepared in the presence of at least one inorganic multivalent crosslinking agent, while in other embodiments, the acrylic resin is first prepared and then combined with at least one inorganic multivalent crosslinking agent. In other embodiments, the acrylic resin is prepared and stored, and then combined with at least one inorganic multivalent crosslinking agent (as a solid or as a solution, suspension or dispersion in an aqueous medium), and the two are thoroughly mixed before the coating composition is applied to the substrate surface.

[0052] When the coating composition is applied to a substrate, the composition cures to form a cured coating. In some embodiments, the initial curing period spans, for example, less than four weeks from the time the coating composition is applied. In some embodiments, the initial curing period ranges, for example, eighteen hours to four weeks, one day to three weeks, three days to two weeks, and one week to two weeks. Additionally, as mentioned above, the curing time may be accelerated when the coated substrate is heated.

[0053] Once prepared, the paint composition can be dispensed into any desired storage container, such as a paint can. The paint composition can then be transported and stored, such as in a warehouse or on a storage shelf.

[0054] In some embodiments, the disclosed coating compositions are particularly useful and reliable when the application temperature of the coating composition can be controlled. In the context of this invention, application temperature refers to the temperature of the substrate on which the coating composition is applied, the ambient temperature of the environment in which the coating composition is applied, or both.

[0055] In some embodiments, the disclosed coating compositions, when formed on a substrate, can form a reliable cured coating, including, for example, masonry or cementitious substrates (including but not limited to cement board or fiber cement board), wood, metal, glass, plastics (e.g., vinyl resin), paper, leather, fabric, ceramics, composite materials, and any combination thereof. The coatings of embodiments of the invention can have any desired dry film thickness, including but not limited to dry film thicknesses in the range of, for example, 0.3 mils to about 10 mils (about 7.6 micrometers to about 254 micrometers). In some other embodiments, the coatings of the invention can have a dry film thickness in the range of, for example, 0.3 mils to about 2.2 mils (about 7.6 micrometers to about 55.9 micrometers).

[0056] In some embodiments of the invention, the coating composition of the present invention can be used as a primer on a substrate. In other embodiments of the invention, the coating composition of the present invention can be used as a topcoat on a substrate. In other embodiments of the invention, the coating composition of the present invention can serve as both a primer and a topcoat on a substrate (i.e., a single-coat coverage composition). In yet another embodiment, the coating composition of the present invention can be applied to a previously coated substrate.

[0057] In some embodiments, the coating compositions of the present invention provide improved storage stability under industrial conditions.

[0058] In some embodiments, the coating composition may be applied to the substrate by roller coating, spraying, curtain coating, dip coating, brush coating, or some other suitable coating process. In some embodiments, at least a portion of the substrate may be coated with the coating composition.

[0059] In addition, the cured coating formed by the coating composition disclosed herein can adequately protect the substrate when exposed to various temperatures and weather conditions, including but not limited to wood, metal, plastic, masonry or cementitious substrates, and composite materials.

[0060] Example :

[0061] The following embodiments are provided to illustrate the present invention and its advantages, but should not be construed as limiting the scope of the invention.

[0062] The adhesion of the waterborne acrylic coating compositions according to embodiments of the invention was tested by coating cementitious substrates with conventional acrylic primer compositions without inorganic multivalent crosslinking agents and with compositions containing 5% by weight of complexed Zn2+ salt and 10% by weight of complexed Zn2+ salt, respectively. The coated cementitious substrate samples were tested according to ASTM 3359 using the 2mm cross-hatched tape test method. The results are shown in... Figure 1 In the figure, it is clearly shown that the composition using the embodiment of the present invention significantly improves surface adhesion compared to conventional primers without inorganic multivalent crosslinking agents.

[0063] Cobb tests (according to ASTM D5795) were also performed on substrate samples coated with conventional acrylic primers and substrate samples coated with embodiments of the coating compositions of the present invention. The results showed that, based on the Cobb test results compared to the control, the present invention provides a significant improvement in permeability.

[0064] The weathering properties of substrates coated with embodiments of the present invention were also tested and compared with a control using a conventional acrylic primer without inorganic multivalent crosslinking agents. Tests were conducted on cementitious substrates according to ASTM C1225. Visual inspection of noticeable changes in gloss under ambient light helped identify the weathering front resulting from wicking within the substrate. These results indicate that the movement of the weathering front on cementitious substrates coated with the waterborne acrylic coating compositions of embodiments of the present invention was minimal compared to the control.

[0065] Similarly, adhesion tests according to ASTM 02793 show that the coatings of the embodiments of the present invention provide a significant improvement in adhesion properties compared to coatings formed from conventional acrylic coating compositions that do not contain inorganic multivalent crosslinking agents.

[0066] The following are some non-limiting examples of embodiments of the present invention:

[0067] Implementation Scheme 1. A waterborne acrylic coating composition, said waterborne acrylic coating composition comprising:

[0068] An acrylic resin having a unit formed from at least one monomer containing a (meth)acrylic acid unit, wherein the acrylic resin has a plurality of reactive groups selected from hydroxyl groups, amino groups and carboxyl groups; at least one inorganic multivalent crosslinking agent that reacts with the plurality of reactive groups and optionally with a surface coated by the aqueous acrylic coating composition; and water.

[0069] Implementation Scheme 2. The waterborne acrylic coating composition according to Implementation Scheme 1, wherein the acrylic resin is a single-stage acrylic resin.

[0070] Implementation Scheme 3. The waterborne acrylic coating composition according to Implementation Scheme 1, wherein the acrylic resin is a multi-stage resin.

[0071] Implementation Scheme 4. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 3, wherein the at least one monomer containing a (meth)acrylic unit is at least one (meth)acrylic alkyl ester.

[0072] Implementation Scheme 5. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 4, wherein the at least one monomer containing a (meth)acrylic unit is at least one C1-C6 (meth)acrylic alkyl ester.

[0073] Implementation Scheme 6. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 5, wherein the at least one monomer containing a (meth)acrylic acid unit is at least one member selected from the group consisting of: methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, isopropyl acrylate, isopropyl methacrylate, n-propyl acrylate, n-propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, isopentyl acrylate, isopentyl methacrylate, neopentyl acrylate, neopentyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, isohexyl acrylate, isohexyl methacrylate, neohexyl acrylate, neohexyl methacrylate, cyclobutyl acrylate, cyclobutyl methacrylate, cyclopentyl acrylate, cyclopentyl methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate.

[0074] Implementation Scheme 7. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 6, wherein the at least one inorganic multivalent crosslinking agent is at least one member selected from the group consisting of: Zn salt, Ca salt, Mg salt, Cu salt, Al salt, Mn salt and Fe salt.

[0075] Implementation Scheme 8. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 7, wherein the at least one inorganic multivalent crosslinking agent is a member selected from Zn salts and Ca salts.

[0076] Implementation Scheme 9. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 8, wherein the at least one inorganic multivalent crosslinking agent is a Zn salt.

[0077] Implementation Scheme 10. The waterborne acrylic coating composition according to Implementation Scheme 9, wherein the Zn salt comprises complexed Zn. 2+ Salt.

[0078] Implementation Scheme 11. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 10, wherein the at least one inorganic multivalent crosslinking agent is present in the composition in an amount of 3% to 15% by weight based on the total composition.

[0079] Implementation Scheme 12. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 11, wherein the waterborne acrylic coating composition further comprises at least one additional acrylic latex.

[0080] Implementation Scheme 13. The waterborne acrylic coating composition of claim 12, wherein the at least one additional acrylic latex comprises an acrylic copolymer.

[0081] Implementation Scheme 14. The waterborne acrylic coating composition according to Implementation Scheme 13, wherein the acrylic copolymer is a copolymer of at least one monomer containing a (meth)acrylic acid unit and another monomer, wherein the other monomer may be a monomer containing a (meth)acrylic acid unit or an unsaturated monomer without a (meth)acrylic acid unit.

[0082] Implementation Scheme 15. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 14, wherein the waterborne acrylic coating composition further comprises at least one member selected from the group consisting of: plasticizers, thickeners, defoamers, surfactants, dispersants, matting agents, solvents, antimicrobial agents, pigments, hardeners, pH adjusters, waxes, and combinations thereof.

[0083] Implementation Scheme 16. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 15, wherein the composition is a primer composition.

[0084] Implementation Scheme 17. The waterborne acrylic coating composition according to any one of Implementation Schemes 1 to 16, wherein the composition is a topcoat composition.

[0085] Embodiment 18. A coated substrate comprising an aqueous acrylic coating composition according to any one of Embodiments 1 to 17 applied to at least a portion of the substrate.

[0086] Implementation Scheme 19. The coated substrate according to Implementation Scheme 18, wherein the substrate comprises at least one member selected from the group consisting of: wood, metal, glass, plastic, paper, leather, fabric, ceramic, cement, cement board, composite material, and any combination thereof.

[0087] Implementation Scheme 20. A coated substrate according to one of Implementation Schemes 18 or 19, wherein the substrate is a member selected from the group consisting of cement and cement board.

[0088] Implementation Scheme 21. A coated substrate according to any one of Implementation Schemes 18 to 20, wherein the coating composition is applied to the substrate by a method selected from the group consisting of roller coating, spraying, curtain coating, dip coating and brush coating.

[0089] Implementation Scheme 22. A coated substrate according to any one of Implementation Schemes 18 to 21, wherein the coating composition is internally cross-linked by the at least one inorganic cross-linking agent, and wherein the coating composition is bonded to reactive groups on the surface of the substrate by the at least one inorganic cross-linking agent.

[0090] This written description uses examples to disclose the invention, including the best mode, and also enables those skilled in the art to practice the invention, including making and using any device or system and performing any combination of methods. The patentable scope of the invention is defined by the claims and may include other examples that may occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

[0091] Based on the foregoing teachings, additional modifications and variations of the invention are possible. Therefore, it should be understood that, within the scope of the appended claims, the invention may be practiced in ways other than those specifically described herein.

Claims

1. A waterborne acrylic coating composition, said waterborne acrylic coating composition comprising: An acrylic resin having a unit formed from at least one monomer containing a (meth)acrylic acid unit, wherein the acrylic resin has a plurality of reactive groups selected from hydroxyl groups, amino groups and carboxyl groups; at least one inorganic multivalent crosslinking agent that reacts with the plurality of reactive groups and optionally with a surface coated by the aqueous acrylic coating composition; and water.

2. The waterborne acrylic coating composition according to claim 1, wherein the acrylic resin is a single-stage acrylic resin.

3. The waterborne acrylic coating composition according to claim 1, wherein the acrylic resin is a multi-stage resin.

4. The waterborne acrylic coating composition according to claim 1, wherein the at least one monomer containing a (meth)acrylic unit is at least one (meth)acrylic alkyl ester.

5. The waterborne acrylic coating composition according to claim 1, wherein the at least one monomer containing a (meth)acrylic unit is at least one C1-C6 (meth)acrylic alkyl ester.

6. The waterborne acrylic coating composition according to claim 1, wherein the at least one monomer containing a (meth)acrylic acid unit is at least one member selected from the group consisting of: methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, isopropyl acrylate, isopropyl methacrylate, n-propyl acrylate, n-propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, isopentyl acrylate, isopentyl methacrylate, neopentyl acrylate, neopentyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, isohexyl acrylate, isohexyl methacrylate, neohexyl acrylate, neohexyl methacrylate, cyclobutyl acrylate, cyclobutyl methacrylate, cyclopentyl acrylate, cyclopentyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate.

7. The waterborne acrylic coating composition according to claim 1, wherein the at least one inorganic multivalent crosslinking agent is at least one member selected from the group consisting of: Zn salt, Ca salt, Mg salt, Cu salt, Al salt, Mn salt, and Fe salt.

8. The waterborne acrylic coating composition according to claim 1, wherein the at least one inorganic multivalent crosslinking agent is selected from Zn salts and Ca salts.

9. The waterborne acrylic coating composition according to claim 1, wherein the at least one inorganic multivalent crosslinking agent is a Zn salt.

10. The waterborne acrylic coating composition according to claim 9, wherein the Zn salt comprises complexed Zn. 2+ Salt.

11. The waterborne acrylic coating composition according to claim 1, wherein the at least one inorganic multivalent crosslinking agent is present in the composition in an amount of 3% to 15% by weight based on the total composition.

12. The waterborne acrylic coating composition according to claim 1, wherein the waterborne acrylic coating composition further comprises at least one additional acrylic latex.

13. The waterborne acrylic coating composition of claim 12, wherein the at least one additional acrylic latex comprises an acrylic copolymer.

14. The waterborne acrylic coating composition according to claim 13, wherein the acrylic copolymer is a copolymer of at least one monomer containing a (meth)acrylic acid unit and another monomer, wherein the other monomer may be a monomer containing a (meth)acrylic acid unit or an unsaturated monomer without a (meth)acrylic acid unit.

15. The waterborne acrylic coating composition of claim 1, further comprising at least one member selected from the group consisting of: plasticizers, thickeners, defoamers, surfactants, dispersants, matting agents, solvents, antimicrobial agents, pigments, hardeners, pH adjusters, waxes, and combinations thereof.

16. The waterborne acrylic coating composition according to claim 1, wherein the composition is a primer composition.

17. The waterborne acrylic coating composition according to claim 1, wherein the composition is a topcoat composition.

18. A coated substrate comprising the waterborne acrylic coating composition of claim 1 applied to at least a portion of the substrate.

19. The coated substrate of claim 18, wherein the substrate comprises at least one member selected from the group consisting of: wood, metal, glass, plastic, paper, leather, fabric, ceramic, cement, cement board, composite material, and any combination thereof.

20. The coated substrate of claim 18, wherein the substrate is a member selected from the group consisting of cement and cement board.

21. The coated substrate according to claim 18, wherein the coating composition is applied to the substrate by a method selected from the group consisting of roller coating, spraying, curtain coating, dip coating and brush coating.

22. The coated substrate according to claim 18, wherein the coating composition is internally cross-linked by the at least one inorganic cross-linking agent, and wherein the coating composition is bonded to reactive groups on the surface of the substrate by the at least one inorganic cross-linking agent.

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