JP7766599B2 - One-component water-based self-healing epoxy formulation - Google Patents

Description

Detailed Description of the Invention

[0001] This application claims priority benefit of the earlier filing date of, among other things, U.S. Provisional Patent Application No. 62/957,022, filed January 3, 2020, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION
[0002] Embodiments herein relate to the field of epoxy coatings, and more particularly to one-component waterborne epoxy coatings based on epoxy-amine adduct resins that exhibit surprising adhesion retention and corrosion resistance after degradation when combined with microencapsulated healing agents comprising epoxy resins.

[background]
[0003] There is a steadily increasing demand for low volatile organic content (VOC) coatings that are easy to apply and can protect assets in a wide range of corrosive environments. Waterborne coatings are a desirable approach to reducing these VOCs. However, waterborne coatings have traditionally been unable to exhibit performance levels comparable to those of solvent-based coatings.

[0004] Nevertheless, water-based coatings are representing a larger and growing portion of the coatings market for the protection of a wide range of substrates as they offer a less hazardous and more environmentally friendly alternative to solvent-borne coatings. The use of water-based formulations also offers the added benefit of easier equipment cleanup, dramatically reducing the health, safety, and environmental risks associated with the use of traditional solvent-based coatings.

[0005] Embodiments will be readily understood from the following detailed description in combination with the accompanying drawings and appended claims. Embodiments are illustrated by way of example, but not by way of limitation, in the figures of the accompanying drawings.

FIG. 1 shows the differential scanning calorimetry (DSC) profiles of a standard bisphenol A-(epichlorohydrin) epoxy resin and a cured one-component water-based epoxy-amine adduct resin system obtained separately and in a 1:1 combination by weight. Figures 2A-2B illustrate the solvent exposure of cured samples of one-component waterborne epoxy-amine adduct resins. One part cured resin was mixed with nine parts of the indicated solvent. The resin/solvent samples, from left to right, are as follows: control (no solvent), water, benzyl acetate, hexyl acetate, octyl acetate, and phenylethyl acetate. Figure 2A illustrates the vial immediately after solvent was added to the cured resin. Figure 2B illustrates the vial after four hours at ambient laboratory conditions. Figures 2A-2B illustrate the solvent exposure of cured samples of one-component waterborne epoxy-amine adduct resins. One part cured resin was mixed with nine parts of the indicated solvent. The resin/solvent samples, from left to right, are as follows: control (no solvent), water, benzyl acetate, hexyl acetate, octyl acetate, and phenylethyl acetate. Figure 2A illustrates the vial immediately after solvent was added to the cured resin. Figure 2B illustrates the vial after four hours at ambient laboratory conditions. Figures 3A-3C illustrate the preparation of lap shear joints for shear strength testing. Figure 3A shows a lap joint coated with a one-component waterborne epoxy-amine adduct resin system to create a 1 inch x 1 inch coated area. Figure 3B shows a control assembled lap joint. Figure 3C shows an assembled lap joint in which a healer formulation was applied between the cured epoxy-amine adduct coated coupons. Figures 3A-3C illustrate the preparation of lap shear joints for shear strength testing. Figure 3A shows a lap joint coated with a one-component waterborne epoxy-amine adduct resin system to create a 1 inch x 1 inch coated area. Figure 3B shows a control assembled lap joint. Figure 3C shows an assembled lap joint in which a healer formulation was applied between the cured epoxy-amine adduct coated coupons. Figures 3A-3C illustrate the preparation of lap shear joints for shear strength testing. Figure 3A shows a lap joint coated with a one-component waterborne epoxy-amine adduct resin system to create a 1 inch x 1 inch coated area. Figure 3B shows a control assembled lap joint. Figure 3C shows an assembled lap joint in which a healer formulation was applied between the cured epoxy-amine adduct coated coupons. Figure 4 is a graph showing a summary of the results of lap shear testing of a waterborne epoxy-amine adduct resin system. Lap joints were prepared as described in Example 3 and shown in Figures 3A-3C. The summary results include two controls. For the first control, a one-component waterborne epoxy-amine adduct resin was applied to the two pieces comprising the lap joint, followed by immediate assembly of the lap joint. The lap joint was then left at ambient conditions for six days before lap shear testing (Control 1). For the second control (Control 2), the one-component waterborne epoxy-amine adduct resin was applied to the pieces of the lap joint, allowed to cure for three days, and then the pieces were assembled together to form the lap joint and left at ambient temperature for an additional three days before lap shear testing. To evaluate the effect of the healer formulation, components, and component solvent substitutes on the epoxy-amine adduct, lap shear specimens were prepared as described in Control 2, and the formulations applied between the coated pieces of the lap joint before assembly were tested. The formulations tested included a healer formulation, bisphenol A-(epichlorohydrin) epoxy resin, benzyl acetate, hexyl acetate, octyl acetate, and phenylethyl acetate. As was done in the case of Control 2, the lap joints were allowed to rest at ambient conditions for 3 days before lap shear testing. 5A-5D are diagrams illustrating a waterborne epoxy-amine adduct-based coating system applied to a steel substrate or a steel substrate primed with a zinc-rich primer. Figure 5A illustrates one coat of a comparative coating formulation, followed by a topcoat. Figure 5B illustrates one coat of a formulation of the present disclosure incorporating a microencapsulated healer formulation (e.g., a one-component waterborne epoxy-amine adduct-based coating), followed by a topcoat. Figure 5C illustrates two coats of a comparative coating formulation, followed by a topcoat. Figure 5D illustrates two coats of a formulation of the present disclosure incorporating a microencapsulated healer formulation, followed by a topcoat. 5A-5D are diagrams illustrating a waterborne epoxy-amine adduct-based coating system applied to a steel substrate or a steel substrate primed with a zinc-rich primer. Figure 5A illustrates one coat of a comparative coating formulation, followed by a topcoat. Figure 5B illustrates one coat of a formulation of the present disclosure incorporating a microencapsulated healer formulation (e.g., a one-component waterborne epoxy-amine adduct-based coating), followed by a topcoat. Figure 5C illustrates two coats of a comparative coating formulation, followed by a topcoat. Figure 5D illustrates two coats of a formulation of the present disclosure incorporating a microencapsulated healer formulation, followed by a topcoat. 5A-5D are diagrams illustrating a waterborne epoxy-amine adduct-based coating system applied to a steel substrate or a steel substrate primed with a zinc-rich primer. Figure 5A illustrates one coat of a comparative coating formulation, followed by a topcoat. Figure 5B illustrates one coat of a formulation of the present disclosure incorporating a microencapsulated healer formulation (e.g., a one-component waterborne epoxy-amine adduct-based coating), followed by a topcoat. Figure 5C illustrates two coats of a comparative coating formulation, followed by a topcoat. Figure 5D illustrates two coats of a formulation of the present disclosure incorporating a microencapsulated healer formulation, followed by a topcoat. 5A-5D are diagrams illustrating a waterborne epoxy-amine adduct-based coating system applied to a steel substrate or a steel substrate primed with a zinc-rich primer. Figure 5A illustrates one coat of a comparative coating formulation, followed by a topcoat. Figure 5B illustrates one coat of a formulation of the present disclosure incorporating a microencapsulated healer formulation (e.g., a one-component waterborne epoxy-amine adduct-based coating), followed by a topcoat. Figure 5C illustrates two coats of a comparative coating formulation, followed by a topcoat. Figure 5D illustrates two coats of a formulation of the present disclosure incorporating a microencapsulated healer formulation, followed by a topcoat. 6A-6B illustrate waterborne epoxy-amine adduct-based systems for non-ferrous metals and porous substrates. Figure 6A illustrates a comparative coating formulation. Figure 6B illustrates a formulation of the present disclosure incorporating a microencapsulated healing agent formulation. 6A-6B illustrate waterborne epoxy-amine adduct-based systems for non-ferrous metals and porous substrates. Figure 6A illustrates a comparative coating formulation. Figure 6B illustrates a formulation of the present disclosure incorporating a microencapsulated healing agent formulation. 7A-7B are representative images showing adhesion loss by scribing a coated substrate to cold rolled steel (CRS) after 1000 hours of salt fog exposure (American Society for Testing and Materials (ASTM) B117) for a comparative one-component waterborne epoxy-amine adduct-based coating formulation and acrylic topcoat, and one coating of a formulation of the present disclosure incorporating 2.5 wt % of a microencapsulated healer formulation and acrylic topcoat. Figure 7A illustrates the comparative waterborne epoxy-amine adduct-based system. Figure 7B illustrates the formulation of the present disclosure incorporating 2.5 wt % of a microencapsulated healer formulation. 7A-7B are representative images showing adhesion loss by scribing a coated substrate to cold rolled steel (CRS) after 1000 hours of salt fog exposure (American Society for Testing and Materials (ASTM) B117) for a comparative one-component waterborne epoxy-amine adduct-based coating formulation and acrylic topcoat, and one coating of a formulation of the present disclosure incorporating 2.5 wt % of a microencapsulated healer formulation and acrylic topcoat. Figure 7A illustrates the comparative waterborne epoxy-amine adduct-based system. Figure 7B illustrates the formulation of the present disclosure incorporating 2.5 wt % of a microencapsulated healer formulation. 8A-8B show representative images of adhesion loss after 1000 hours of salt fog exposure (ASTM B117) by scribing the coated substrate against blasted steel for a comparative one-component waterborne epoxy-amine adduct-based coating formulation and a two-component solvent-borne hydroxyl-functional acrylic topcoat, and two coatings of the present version incorporating 5 wt % of a microencapsulated healer formulation with the two-component solvent-borne hydroxyl-functional acrylic topcoat. Figure 8A illustrates the comparative waterborne epoxy-amine adduct-based system, and Figure 8B illustrates the present waterborne epoxy-amine adduct-based system incorporating 5 wt % of a microencapsulated healer formulation. 8A-8B show representative images of adhesion loss after 1000 hours of salt fog exposure (ASTM B117) by scribing the coated substrate against blasted steel for a comparative one-component waterborne epoxy-amine adduct-based coating formulation and a two-component solvent-borne hydroxyl-functional acrylic topcoat, and two coatings of the present version incorporating 5 wt % of a microencapsulated healer formulation with the two-component solvent-borne hydroxyl-functional acrylic topcoat. Figure 8A illustrates the comparative waterborne epoxy-amine adduct-based system, and Figure 8B illustrates the present waterborne epoxy-amine adduct-based system incorporating 5 wt % of a microencapsulated healer formulation. 9A-9B show representative images of scribe adhesion loss of coated substrates to blasted steel after 1000 hours of salt fog exposure (ASTM B117) for a zinc-rich primer and either a comparative one-component epoxy-amine adduct-based coating or a formulation of the present disclosure incorporating 2.5 wt % of a microencapsulated healer formulation as a structural coating, both with a hydroxyl-functional acrylic topcoat. Figure 9A illustrates the comparative one-component waterborne epoxy-amine adduct-based system. Figure 9B illustrates the present one-component waterborne epoxy-amine adduct-based system incorporating 2.5 wt % of a microencapsulated healer formulation. 9A-9B show representative images of scribe adhesion loss of coated substrates to blasted steel after 1000 hours of salt fog exposure (ASTM B117) for a zinc-rich primer and either a comparative one-component epoxy-amine adduct-based coating or a formulation of the present disclosure incorporating 2.5 wt % of a microencapsulated healer formulation as a structural coating, both with a hydroxyl-functional acrylic topcoat. Figure 9A illustrates the comparative one-component waterborne epoxy-amine adduct-based system. Figure 9B illustrates the present one-component waterborne epoxy-amine adduct-based system incorporating 2.5 wt % of a microencapsulated healer formulation. Figures 10A-10B show representative images showing substrate corrosion away from the scribe for a coated aluminum 2024-T3 substrate after 1500 hours of salt fog exposure (ASTM B117). Figure 10A illustrates a comparative one-component waterborne epoxy-amine adduct-based coating. Figure 10B illustrates a formulation of the present disclosure incorporating 2.5 wt% of a microencapsulated healer formulation. Figures 10A-10B show representative images showing substrate corrosion away from the scribe for a coated aluminum 2024-T3 substrate after 1500 hours of salt fog exposure (ASTM B117). Figure 10A illustrates a comparative one-component waterborne epoxy-amine adduct-based coating. Figure 10B illustrates a formulation of the present disclosure incorporating 2.5 wt% of a microencapsulated healer formulation. 11A-11B show representative images of coated concrete substrates after 7 days of waterlogged exposure. Figure 11A illustrates a comparative one-component waterborne epoxy-amine adduct-based coating. Figure 11B illustrates a formulation of the present disclosure incorporating 2.5 wt. % of a microencapsulated healing agent formulation. 11A-11B show representative images of coated concrete substrates after 7 days of waterlogged exposure. Figure 11A illustrates a comparative one-component waterborne epoxy-amine adduct-based coating. Figure 11B illustrates a formulation of the present disclosure incorporating 2.5 wt. % of a microencapsulated healing agent formulation. 12A-12B show representative images and photomicrographs of coated wood substrates after one cycle of immersion and freeze exposure. Figure 12A illustrates a comparative one-component waterborne epoxy-amine adduct-based coating. Figure 12B illustrates a formulation of the present disclosure incorporating 2.5 wt. % of a microencapsulated healing agent formulation. 12A-12B show representative images and photomicrographs of coated wood substrates after one cycle of immersion and freeze exposure. Figure 12A illustrates a comparative one-component waterborne epoxy-amine adduct-based coating. Figure 12B illustrates a formulation of the present disclosure incorporating 2.5 wt. % of a microencapsulated healing agent formulation. Figure 13 is a table showing adhesion loss by scribe for one-component waterborne epoxy-amine adduct-based systems on steel substrates or steel substrates primed with a zinc-rich primer. The comparative examples do not include a microencapsulated healer. The test examples incorporate an epoxy-amine adduct-based resin system and a microencapsulated healer formulation according to embodiments herein. Sample Sets 1, 2, and 3 are three unique coating formulations, but all three include a waterborne epoxy-amine adduct-based resin system. Sample Set 4 uses the same waterborne epoxy-amine adduct-based resin system formulation as Sample Set 1, but is applied over a zinc-rich primer.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and which show by way of illustration illustrative embodiments that may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope. Therefore, the following detailed description is not to be taken in a limiting sense.

[0020] Various operations may be described sequentially as several separate operations in a manner that may be useful in understanding the embodiments; however, the order of description should not be construed to imply that these operations are order dependent.

[0021] The present description may use perspectives such as top/bottom, back/front, and top/bottom. Such descriptions are used merely for ease of discussion and are not intended to limit the application of the disclosed embodiments.

[0022] The terms "coupled" and "connected," along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, "connected" may be used to indicate that two or more elements are in direct physical contact with each other. "Coupled" may mean that two or more elements are in direct physical contact. However, "coupled" may also mean that two or more elements are not in direct contact with each other, but still cooperate or interact with each other.

[0023] For purposes of description, a phrase in the form "A/B" or "A and/or B" means (A), (B), or (A and B). For purposes of description, a phrase in the form "at least one of A, B, and C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C). For purposes of description, a phrase in the form "(A)B" means (B) or (AB), i.e., A is an optional element.

[0024] The description may use the terms "embodiment" or "embodiments," which may each refer to one or more of the same or different embodiments. Furthermore, terms such as "comprising," "including," and "having" when used with respect to embodiments are synonymous and generally intended as "open" terms. (For example, the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "including but not limited to," etc.)

[0025] With respect to the use of any plural and/or singular terms herein, those skilled in the art may translate from plural to singular and/or from singular to plural as appropriate to the context and/or application. Various singular/plural permutations may be expressly stated herein for clarity.

[0026] Embodiments herein provide self-healing coating formulations. The self-healing coating formulations, when applied to a substrate, can harden to form a protective coating or sealant. The self-healing coating formulation may be comprised of a one-component water-based epoxy-amine adduct resin system and a microencapsulated healer. The one-component water-based epoxy-amine adduct resin system and the microencapsulated healer may be synergistic with each other such that the coating formulation exhibits improved adhesion retention and corrosion resistance of the coating after a certain level of damage (e.g., degradation) to the coating system exposing the underlying substrate.

[0027] In embodiments, coating systems containing these base components (e.g., a one-component waterborne epoxy-amine adduct resin system and a microencapsulated healing agent) exceed the performance of alternative formulations containing the resin alone, without the microencapsulated healing agent, in terms of adhesion maintenance and corrosion resistance.

[0028] The one-component waterborne resin system of the present disclosure may include an epoxy amine adduct resin system. This resin chemistry is based on a one-component epoxy system containing pre-reacted epoxy groups stabilized in water at low pH. When this stabilized pre-reacted resin system is applied to a substrate and the water in the matrix evaporates from the system, these pre-reacted particles coalesce to form a fast-curing epoxy coating matrix. This, in turn, eliminates the need to formulate two separate components to create an epoxy coating and eliminates the need to mix the two components in the field prior to application. Advantages include versatile, simpler, easier, and less hazardous coatings.

[0029] As an example, one component may include a waterborne epoxide that self-cures using a deactivated amine that is activated upon evaporation or removal of water. The amines discussed herein may refer to simple amines and polyamines. Such compositions may be prepared by first emulsion polymerization of the epoxide in an alkaline amine-containing medium. The reaction may then be stopped by neutralization and deactivation of the amine. Spreading of the resulting composition in a thin film layer and subsequent evaporation of the water can activate the amine in the composition that cures the epoxy. It is within the scope of this disclosure for the one-component waterborne resin systems of the present disclosure to further include pigments or other particulate materials, reactive or non-reactive resins and polymers, flow control agents, pigment grinding aids, and the like.

[0030] Microencapsulated self-healing coatings are a novel class of smart coating technology. These technologies can increase the service life of coating systems and the underlying substrates they protect through in-situ autonomous repair of coating damage. Embodiments herein are directed to self-healing functionality achieved through the incorporation of specific microencapsulated healer formulations into one-component epoxy coating formulations. It is shown herein that the addition of self-healing functional groups to water-based epoxy coating formulations can facilitate adhesion maintenance of the coating system at the damaged site and, surprisingly, can even increase the adhesive strength of the film in the damaged area.

[0031] Accordingly, embodiments include a self-healing coating formulation that includes a one-component water-based resin system and a healing agent encapsulated in microcapsules. The self-healing coating formulation, when applied to a substrate, can harden to form a protective coating or sealant.

[0032] It can be understood that there can be any number (e.g., multiple) of microcapsules associated with such a self-healing coating formulation. By way of example, the microcapsules are comprised of a shell wall (e.g., a polymeric shell wall). By way of example, the shell wall may be comprised of one or more of urea formaldehyde, melamine formaldehyde, polyacrylate, polyurea, poly(ethylene-co-maleic anhydride), and polyurethane. By way of example, the microcapsule(s) are of an average diameter between 5 and 50 microns. In some examples, the average diameter is 25 microns or less.

[0033] In an example of a self-healing coating formulation, the healer may further include one or more of an epoxy resin, a solvent (e.g., a polar aprotic solvent), and an alkoxysilane. The alkoxysilane may be one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methacrylpropyltrimethoxysilane, and methacrylpropyltriethoxysilane. In certain examples, the alkoxysilane is a glycidylalkoxysilane. For example, the glycidylalkoxysilane may be one or both of 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane. As discussed herein, alkoxysilanes include adhesion promoters and corrosion inhibitors. In some examples, the healer corresponding to the self-healing coating formulation may exclude (e.g., not include) an alkoxysilane, while the self-healing coating formulation may retain the self-healing properties discussed herein. For example, it is contemplated that the self-healing coating formulations disclosed herein, excluding alkoxysilanes, may be used on surfaces that do not corrode.

[0034] In example self-healing coating formulations, the polar aprotic solvent may be hydrophobic. By way of example, the polar aprotic solvent may have one or more of the following properties: By way of example, the polar aprotic solvent may have a miscibility with water of 5 g/L or less, e.g., 3-5 g/L, or 1-3 g/L, or 1-5 g/L, or 0.1-5 g/L, or 0.1-3 g/L, or 0.1-1 g/L, or 0.1-0.5 g/L, or even less than 0.1 g/L. Miscibility of at least 5 g/L or less may be advantageous for stabilizing oil-in-water emulsions for microencapsulation of healing agents in the context of the self-healing coating formulations discussed herein. Notably, as solvent miscibility increases, encapsulation efficiency may decrease.

[0035] By way of example, the polar aprotic solvent may have a boiling point of 190°C or greater. For example, the boiling point of the aprotic solvent may be selected to be in the range between 190°C and 300°C, e.g., between 190°C and 250°C. A boiling point above 190°C can ensure the usefulness of assets with high surface temperatures.

[0036] By way of example, the polar aprotic solvent may have a vapor pressure of 0.5 mmHg or less at 25°C, such as between 0.1 and 0.5 mmHg, or between 0.05 mmHg and 0.5 mmHg, or even less than 0.05 mmHg. A vapor pressure of 0.5 mmHg or less at 25°C may allow sufficient time for the healing agent to flow to the site of degradation upon rupture of the microcapsules to facilitate a self-healing response. In other words, a solvent with a vapor pressure greater than 0.5 mmHg at 25°C may evaporate at a rate that reduces the ability of the healing agent to reach/approach the degradation site, thereby reducing the self-healing properties of the coating formulation.

[0037] By way of example, polar aprotic solvents may have a dielectric constant greater than 5. The dielectric constant of solvents relevant to the self-healing coating formulations discussed herein, among others, is used as a measure of polarity. Increased polarity is advantageous in terms of one or more of promoting entanglement of the interpenetrating chains in the coating network and reactivity with available amine functional groups.

[0038] In some examples, the polar aprotic solvent may include all of the above properties, particularly miscibility with water of 5 g/L or less, a boiling point of 190°C or greater, a vapor pressure of 0.5 mmHg or less at 25°C, and a dielectric constant of 5 or greater. However, it is within the scope of this disclosure that in other examples, the polar aprotic solvent may not include all of the above properties, but may include only one, two, or three of the above properties.

[0039] Thus, by way of example, the polar aprotic solvent may include one or more of benzyl acetate, ethyl phenylacetate, phenyl acetate, hexyl acetate, octyl acetate, phenethyl acetate, and nitrobenzene. In other examples, the polar aprotic solvent may include at least one or more of benzyl acetate, ethyl phenylacetate, phenyl acetate, hexyl acetate, octyl acetate, phenethyl acetate, nitrobenzene, tetrahydrofuran (THF), dichloromethane, N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), acetonitrile, dimethylacetamide (DMA), and dimethylformamide (DMF).

[0040] In an example of a self-healing coating formulation, the epoxy resin may further include bisphenol A-(epichlorohydrin) epoxy resin. Specifically, the resin may be produced by combining epichlorohydrin and bisphenol A to provide a bisphenol A diglycidyl ether epoxy resin. It is within the scope of the present disclosure that, instead of bisphenol A, other bisphenols (e.g., bisphenol F) or brominated bisphenols (e.g., tetrabromobisphenol A) may be used to form the epoxy resins of the present disclosure.

[0041] By way of example, the healing agent may comprise between 5% and 95% by weight (e.g., 5-10% by weight, or 10-20% by weight, or 20-30% by weight, or 30-40% by weight, or 40-50% by weight, or 50-60% by weight, or 60-70% by weight, or 70-80% by weight, or 80-90% by weight, or 90-95% by weight) of an epoxy resin. By way of example, the healing agent may comprise between 5% and 95% by weight (e.g., 5-10% by weight, or 10-20% by weight, or 20-30% by weight, or 30-40% by weight, or 40-50% by weight, or 50-60% by weight, or 60-70% by weight, or 70-80% by weight, or 80-90% by weight, or 90-95% by weight) of a polar aprotic solvent. For example, the healing agent may contain between 0% and 10% by weight (e.g., 0-1%, or 1-2%, or 2-3%, or 3-4%, or 4-5%, or 5-6%, or 6-7%, or 7-8%, or 8-9%, or 9-10%) of alkoxysilane.

[0042] By way of example, the one-component waterborne resin system may further include an epoxy amine adduct resin system. Such waterborne resin systems (e.g., epoxy amine adduct resin systems) discussed herein may be prepared by emulsifying an epoxy resin in water, followed by one or more reactions with an amine, and then stabilizing using an acid. Such epoxy amine adduct systems are described, for example, in U.S. Pat. No. 6,121,350.

[0043] Another embodiment includes a method of protecting a substrate. The method may include applying to the substrate a formulation including a one-component water-based resin system and a healing agent encapsulated in one or more microcapsules (e.g., a plurality of microcapsules). Upon application to the substrate, the formulation can harden to form a protective material. Degradation of the protective material can result in rupture of the microcapsules at the degradation site and release of the healing agent.

[0044] In such methods, the one-component water-based resin system may further include an epoxy amine adduct resin system. The restorative agent may further include an epoxy resin, a polar aprotic solvent, and an alkoxysilane.

[0045] As an example of such a method, the release of a healing agent in response to microcapsule rupture can promote non-covalent entanglement of the oligomeric components of the epoxy amine adduct resin system. The release of the healing agent can additionally or alternatively promote a covalent cross-linking reaction between the epoxy resin present in the healing agent and available amine groups in the protective material.

[0046] In one example of such a method, the epoxy resin may further include bisphenol A (epichlorohydrin). The polar aprotic solvent may be one or more of benzyl acetate, ethyl phenylacetate, phenyl acetate, hexyl acetate, octyl acetate, phenethyl acetate, nitrobenzene, chlorobenzene, tetrahydrofuran (THF), dichloromethane, N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), acetonitrile, dimethylacetamide (DMA), and dimethylformamide (DMF). The alkoxysilane may be one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methacrylpropyltrimethoxysilane, and methacrylpropyltriethoxysilane.

[0047] In one example of such a method, the microcapsules may further comprise a polymeric shell wall. The polymeric shell wall may be comprised of one or more of urea formaldehyde, melamine formaldehyde, polyacrylate, polyurea, poly(ethylene-co-maleic anhydride), and polyurethane. By way of example, the average diameter of the microcapsule(s) may be between 5 and 50 microns. In some examples, the average diameter of the microcapsules may be less than 25 microns.

[0048] In examples of such methods, degradation may further include one or more of mechanical failure, scratching, cracking, nicking, or other loss of integrity of the protective material. In some examples, rupture of the microcapsules and release of the healing agent at the degradation site reduces corrosion by limiting the ingress of moisture and electrolytes compared to a protective material lacking the encapsulated healing agent. By way of example, the substrate is one of steel, aluminum, concrete, and wood.

[0049] In one example, applying the formulation to the substrate may further include coating the substrate with a primer including an inorganic coating binder to form a first coating layer. Applying the formulation may further include coating the primer with an organic coating including an organic coating binder to form a second coating layer. The formulation may then be applied over the second coating layer as an overcoat layer. In such an example, the primer may further include a zinc-rich primer. The zinc-rich primers discussed herein may relate to inorganic or organic coatings, and the zinc content may be greater than 20 wt%, greater than 30 wt%, greater than 40 wt%, greater than 50 wt%, greater than 60 wt%, greater than 70 wt%, greater than 80 wt%, or even greater than 90 wt%. In some examples, the primer additionally includes microcapsule(s) comprised of an encapsulated healing agent; however, in other examples, the primer additionally does not include microcapsule(s) without departing from the scope of the present disclosure. In some examples, the inorganic coating binder may be a silicate binder (e.g., an alkyl silicate binder). In some examples, the organic coating binder may be an epoxy resin cured with one or more of the following curing agents: amines, polyamines, anhydrides, aminosiloxanes, imidazoles, polyamides, ketamines, modified amines that are reaction products of amines and other compounds, mercaptans and polymercaptans, polysulfides, thiols, boron trifluoride amine complexes, organic acid hydrazides, and light and ultraviolet curing agents. For example, a first coating may be mist coated with a second coating (e.g., diluted with water and applied as a thin coat).

[0050] In another embodiment, a method for maintaining adhesion of a protective material to a substrate after degradation of the protective material includes applying to the substrate a water-based epoxy coating formulation including a healing agent encapsulated in microcapsules (e.g., a plurality of microcapsules), wherein the water-based epoxy coating formulation hardens to form the protective material upon application thereof to the substrate. Degradation of the protective material results in rupture of the microcapsule(s) at the degradation site and release of the healing agent, thereby maintaining adhesion of the protective material to the substrate.

[0051] In examples of such methods, degradation of the protective material may result from one or more of mechanical breakage, scratches, cracks, cuts, or other loss of integrity of the protective material.

[0052] In an example of such a method, the water-based resin system is an epoxy amine adduct resin system, and the restorative agent further comprises an epoxy resin, a polar aprotic solvent, and an alkoxysilane.

[0053] In another example of such a method, the rupture of the microcapsules and release of the healing agent maintains the swelling of the protective material with an aprotic solvent, which allows adhesion of the protective material to the substrate and entanglement between the oligomeric resin components of the protective material through a chemical reaction between the amine groups corresponding to the epoxy amine adduct resin system and the epoxy resin of the healing agent.

In an example method, the epoxy resin further comprises bisphenol A-(epichlorohydrin). The polar aprotic solvent may be one or more of benzyl acetate, ethyl phenylacetate, phenyl acetate, hexyl acetate, octyl acetate, phenethyl acetate, nitrobenzene, chlorobenzene, tetrahydrofuran (THF), dichloromethane, N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), acetonitrile, dimethylacetamide (DMA), and dimethylformamide (DMF). The alkoxysilane may be one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methacrylpropyltrimethoxysilane, and methacrylpropyltriethoxysilane. The microcapsule(s) may further comprise a polymeric shell wall composed of one or more of urea formaldehyde, melamine formaldehyde, polyacrylate, polyurea, poly(ethylene-co-maleic anhydride), and polyurethane. The microcapsules may have a diameter of less than 25 microns.

[0055] Through the use of a one-component waterborne epoxy coating, embodiments herein provide a low volatile organic compound (VOC) system that is a one-component coating that leverages the synergy between the microencapsulated healing agent and the novel solvent-promoted entanglement of the oligomeric component of the epoxy amine adduct resin system, as well as the crosslinking of the epoxy resin released from the ruptured microcapsules by the available amine groups during a healing event. By way of example, VOCs are maintained below 50 g/L of the coating formulation. For example, formulations that emit 45 g/L or less, or 40 g/L or less, or 35 g/L or less, or 30 g/L or less, or 25 g/L or less, or 20 g/L or less, or 15 g/L or less, or 10 g/L or less, or 5 g/L or less, or even no VOCs, are within the scope of this disclosure.

[0056] The healing agents discussed herein may also be referred to as core formulations. In certain embodiments, the core formulation is comprised of an epoxy resin, a hydrophobic polar aprotic solvent, and an alkoxysilane, more specifically, a glycidylalkoxysilane, and even more specifically, (3-glycidyloxypropyl)trimethoxysilane.

[0057] In embodiments in which microcapsules are incorporated into a one-component water-based epoxy coating, the one-component water-based epoxy coating can maintain adhesion to the underlying metal substrate (or other substrates, including wood, plastic, concrete, etc.). Incorporation of capsules into a one-component water-based epoxy coating can also improve the barrier properties of the coating after damage (e.g., degradation).

[0058] In embodiments, coatings or coating systems (e.g., self-healing coating systems) incorporating the microcapsules described above exhibit improved adhesion retention and corrosion resistance after degradation exposing the underlying substrate.

[0059] In embodiments, coatings or coating systems (e.g., self-healing coating systems) incorporating the microcapsules described above, as well as one-component waterborne epoxy amine adduct resin systems, exhibit improvement in adhesion retention and corrosion resistance after damage to a range of metal surfaces, including, but not limited to, blasted steel surfaces, lightly ground cold-rolled steel, lightly ground aluminum substrates, and other poorly prepared metal substrates.

[0060] In embodiments, the coating systems described above exhibit improved maintenance of adhesion to concrete surfaces after a level of damage that exposes the underlying substrate.

[0061] In embodiments, the coating systems described above exhibit improved adhesion retention to wood surfaces after a level of damage that exposes the underlying substrate.

[0062] As discussed, embodiments herein provide a synergistic effect between a healing agent and a cured epoxy-amine adduct resin system. The embodiments provide a self-healing waterborne epoxy formulation comprising an epoxy-amine adduct resin system and a microencapsulated healing agent formulation further comprising an epoxy resin, a polar aprotic solvent, and a glycidylalkoxysilane solution. When the cured formulation is damaged, the embedded microcapsules rupture, releasing the healing agent present within the capsules to the damage site, which promotes non-covalent entanglement of the oligomeric components of the resin system and covalent crosslinking between the epoxy resin present in the healing agent and released to the damage site and available amine groups in the cured resin system.

[0063] This unique synergy between a microencapsulated healing agent comprising an epoxy resin and a resin system comprised of an epoxy-amine adduct begins with the fact that microcapsules embedded in the cured epoxy-amine adduct resin system, or a coating formulation comprised of the resin system, rupture and release the healing agent to the damage site when the cured resin or coating is damaged. The healing agent interacts with the cured epoxy-amine adduct resin system when present at the damage site. This interaction between the healing agent and the cured resin system comprises two mechanisms that serve to improve adhesion at the damage site and minimize the ingress of moisture and electrolytes that normally cause corrosion at the damage site. The first of these two mechanisms involves the reaction between the epoxy resin and available amine groups in the cured epoxy-amine adduct that have migrated to the damage site. The second involves the ability of polar aprotic solvents to swell the cured epoxy-amine adduct material, allowing for novel entanglements between the oligomeric resin components available within the resin system. Together, these two mechanisms combine to produce a unique, high-performance self-healing response.

Evidence for the first mechanism, the ability of the amine present in the cured epoxy-amine adduct resin system to react with the epoxy resin present in the curing agent, is provided by data from a differential scanning calorimetry (DSC) experiment shown in Figure 1. Results were obtained according to the procedure outlined in Example 1 below. The data show that no significant exotherm is observed for either the cured one-component waterborne epoxy-amine adduct resin 101 or the bisphenol A-(epichlorohydrin) epoxy resin 102. However, when the two are combined 103, there is a significant exotherm consistent with crosslinking of the epoxide functional groups present in the bisphenol A-(epichlorohydrin) epoxy resin. This mechanism is also consistent with the fact that the epoxy-amine adduct resin is produced by pre-reacting the epoxy resin with an amine. This reaction is then quenched and stabilized using an acid in water. When the resin is applied in a thin film, the water evaporates, driving the reaction to form a cured film. However, residual amine groups remain available and can be utilized by the healing agent to form a thermosetting film at the damaged site.

[0065] The second mechanism involves the ability of the solvent to swell the cured epoxy-amine adduct resin system, allowing it to re-fuse and thereby promote the formation of new chain entanglements. Support for this second mechanism is provided by the experiment outlined in Example 2 and the results obtained in Figures 2A-2B. Figure 2A shows a series of samples of the cured one-component waterborne epoxy-amine adduct resin system immediately after solvent addition, along with a control containing the cured epoxy-amine adduct without solvent addition. After 4 hours (Figure 2B), the epoxy amine adducts that were not exposed or exposed only to water still remained as individual flakes and were not observed to fuse together. However, the solvent-exposed epoxy amine adducts softened and fused together, suggesting plasticization and promotion of fusion by the added solvent. For each of Figures 2A-2B, 1 part of the cured resin was mixed with 9 parts of the indicated solvent. Resin/solvent samples, from left to right, are: control (no solvent), water, benzyl acetate, hexyl acetate, octyl acetate, and phenylethyl acetate.

[0066] In a separate experiment, the cured epoxy-amine adduct resin system was molded into lap joints and cured to determine the degree of oligomer chain entanglement and crosslinking achieved by the healer formulation (which was encapsulated) and the individual components. The experiment is described in detail in Example 3, and a schematic diagram showing the structure of the lap joint is shown in Figures 3A-3C.

[0067] The results of lap shear experiments performed with these samples are summarized in Figure 4. The results showed that the introduction of the healer formulation between two steel substrates coated with a cured epoxy amine adduct resin system resulted in a shear strength equal to that of the epoxy amine adduct resin system (Control 1) and stronger than that of the two cured films combined together (Control 2). Furthermore, samples incorporating the healer were found to exhibit stronger bonds than any single component incorporated. Control 1 is represented by reference numeral 405, Control 2 is represented by reference numeral 406, the bond containing the healer formulation is represented by reference numeral 407, the bisphenol A-(epichlorohydrin) epoxy resin bond is represented by reference numeral 408, the bond containing benzyl acetate is represented by reference numeral 409, the bond containing hexyl acetate is represented by reference numeral 410, the bond containing octyl acetate is represented by reference numeral 411, and the bond containing phenylethyl acetate is represented by reference numeral 412.

The above synergistic effect can be exploited and implemented by incorporating an encapsulated healing agent into a coating formulation based on an epoxy-amine adduct. The process by which the healing agent is encapsulated is provided in Example 4. The resulting microcapsules can be incorporated into the coating in either dry or slurry form; processes used to add the capsules in dry and wet forms to a coating formulation based on an epoxy-amine adduct resin system are provided in Examples 5 and 6, respectively. In effect, the healing agent remains within the capsules in the cured film in a silent form until the coating is damaged. Upon coating damage, the embedded capsules rupture, releasing the healing agent to the damage site. At the damage site, the healing agent formulation plasticizes the epoxy-amine adduct coating, thereby promoting re-coalescence and cross-linking, as discussed above, repairing the damage and maintaining adhesion and protection at the damage site. The performance of the coating formulation was evaluated on steel (Figures 5A-5D), aluminum, concrete, and wood substrates (Figures 6A-6B).

[0069] To determine the effect of encapsulated epoxy healer formulations on the corrosion performance of epoxy-amine adduct-based coating systems, coating formulations incorporating various loadings of microcapsules in dry and wet forms were prepared and tested. Schematics representing the evaluated coating systems are provided in Figures 5A-5D. After curing, the coating systems were scribed and exposed to salt fog for the specified exposure periods. The results of these tests can be seen in Table 1300 in Figure 13. Formulations incorporating the microencapsulated healer performed substantially better than otherwise identical formulations, excluding the microencapsulated healer. Performance improvements ranged from 63% to 79% for ground cold-rolled steel substrates (CRS, SSPC-SP3 substrate formulation) and between 55% and 82% for blasted steel substrates (SSPC-SP10 substrate formulation). A representative set of images comparing a formulation excluding the microencapsulated healing agent (control) and a version incorporating the microencapsulated healing agent (inventive formulation) are provided in Figures 7A-7B (CRS), respectively, and Figures 8A-8B (blasted steel), respectively. Formulations with incorporated microcapsules in wet and dry form were evaluated, and these formulations performed comparably.

To further illustrate the use and versatility of the present formulations, formulation samples were further evaluated on zinc-rich primer-primed steel substrates, aluminum 2024-T3, concrete, and wood substrates. In the case of the zinc-rich primed substrate, the present formulations facilitated improved intercoat adhesion between the epoxy-amine adduct coating formulation and the underlying zinc-rich primer, resulting in generally improved corrosion resistance (Figures 9A-9B). Corrosion resistance was also found to be improved for aluminum 2024-T3 substrates coated with the present formulations relative to the comparative formulations (Figures 10A-10B). In the case of concrete substrates, the present formulations demonstrated improved adhesion relative to the comparative formulations after 7 days of waterlogged exposure (Figures 11A-11B). For coated wood substrates, the present formulations were observed to maintain more cohesive integrity, while the comparative formulations exhibited significant cracking around scribe damage to the coating (Figures 12A-12B).

[0071] Example 1. Differential Scanning Calorimetry
[0072] Samples were prepared for differential scanning calorimetry evaluation as follows: Standard bisphenol A-(epichlorohydrin) epoxy resin was measured into a Tzero aluminum pan. Cured one-component water-based epoxy-amine adduct resin was prepared by first casting the epoxy-amine adduct resin onto a polytetrafluoroethylene (PTFE) sheet, followed by curing at 60°C for 16 hours. The resulting polymer film was then removed from the PTFE sheet and crushed into a coarse powder with a mortar and pestle. This powder was then weighed into a Tzero aluminum pan. A 1:1 mixture of bisphenol A-(epichlorohydrin) epoxy resin and one-component water-based epoxy-amine adduct resin was prepared by mixing equal parts by weight of the standard epoxy resin and the cured one-component water-based epoxy resin in separate containers for 60 seconds, followed by weighing into a Tzero aluminum pan. Separate DSC experiments were performed on these using a gradient method starting at ambient temperature and ramping at a rate of 10° C./min up to 300° C. The data from these tests were then plotted and compared (see FIG. 1).

[0073] Example 2. Evaluation of swelling solvents
[0074] For one set of cured epoxy-amine adduct resin films, solvent swell experiments were performed by first casting the epoxy-amine adduct emulsion resin onto a PTFE sheet and curing it at 60°C for 16 hours. After curing, the polymer film was removed from the PTFE sheet and crushed into a coarse powder using a mortar and pestle. This powder was then added to vials at the specified weight. To each vial, the specified solvent (water, benzyl acetate, hexyl acetate, octyl acetate, or phenylethyl acetate) was added to create a 1:9 ratio of resin to solvent. These components were mixed together using a tongue depressor for 30 seconds and then sealed with a lid. The resulting mixtures were allowed to equilibrate to ambient laboratory temperature and observed over time.

[0075] Example 3. Lap joint preparation and testing.
Lap joints for use in lap shear testing were prepared using 1" x 4" x 0.032" cold rolled steel (CRS) substrates. These substrates were marked with a notch made with a caliper set at 1 inch. A sample of the waterborne epoxy-amine adduct resin was then applied to these substrates from the edge of the panel to the notch, creating a 1" x 1" coated surface on each substrate. Two of these substrates were paired together to assemble the lap joints. For evaluation of the first control (Control 1), the coated substrates were assembled to form a lap joint immediately after coating the component substrates with the waterborne epoxy-amine adduct. For the second control (Control 2), the coated component substrates were allowed to cure at ambient temperature for three days before assembling the lap joints. For evaluation of the healer or component, 0.1 g of each formulation was applied to one substrate of the 1" x 1" coated area pair. The coated area of the second substrate was then applied to the 1" x 1" coated area of each substrate. One was placed on top of the first so that only the 1" coated area was in contact, ensuring perpendicularity and matching of the coated areas. Small binder clips held all of the prepared lap joints together and allowed to equilibrate at room temperature for 3 days. The binder clips were then removed and then tested in a load frame per ASTM D1002.

[0077] Example 4. Microencapsulation of restorative formulations
[0078] 200 mL of deionized _H2O was measured into a clean 1000 mL container. 50 mL of a previously prepared solution of 5 wt% poly(ethylene-co-maleic anhydride) (E400 EMA copolymer) was added to the container. 5 g of urea, 0.5 g of _NH4Cl , and 0.5 g of resorcinol (previously ground) were then added to the container, and the solution was mixed until all ingredients were completely dissolved. The pH of the solution was measured to be between 2.3 and 2.4, and adjusted to 3.5 by dropwise addition of a 5 wt% solution of NaOH. The container was then placed in a water bath on a programmable hot plate. A mixer blade or homogenizer was placed on the container and began to shear the solution at the specified speed (2000 RPM for 25 micron capsules and 6000 RPM for 10 micron capsules). A restorative agent as described herein was then added to the vessel to form an emulsion. The emulsion particle size was measured using a microscope to ensure it was within the desired range. After 10-15 minutes of milling, 12.77 g of a 37 wt % aqueous solution of formaldehyde was added to the vessel. 10-15 drops of octanol were added at regular intervals to prevent foaming. The hot plate was started to raise the temperature of the reaction mixture to 55°C at a rate of 1°C/min (60°C/h). A timer was then set for 4 hours. After the reaction was complete, the reaction mixture was cooled to room temperature, after which the microcapsule isolation process began. The reaction mixture was thoroughly washed to remove excess surfactant and any unreacted components. The washed microcapsules were reslurried with deionized water and spray-dried to obtain microcapsules in dry powder form or maintained in a wet slurry form at 50 wt % solids.

[0079] Example 5. Incorporation of dried capsules into coating formulations.
[0080] The dried, final microcapsules were incorporated into the coating formulation (e.g., epoxy amine adduct resin system) by first adding the required amount of microcapsules (2.5 g, 4 g, or 5 g) at a loading of 2.5 wt%, 4 wt%, or 5 wt% to half of the fully formulated coating (48.75 g, 48 g, or 47.5 g). The mixture was gently blended for 60 seconds using a paddle mixer at medium speed (approximately 800-1000 RPM). The remaining half of the coating formulation (48.75 g, 48 g, or 47.5 g) was then added to the mixture, followed by additional mixing using the same mixing procedure previously described. The resulting coating formulation was then applied to the target substrate.

[0081] Example 6. Incorporation of moist capsules (50% by weight in water) into coating formulations
[0082] Microcapsules were incorporated into the present coating formulations (e.g., epoxy amine adduct resin systems) in their wet final form (50 wt% capsules in water) by first adding the required amount of microcapsules (5 g, 8 g, or 10 g) at a loading of 2.5 wt%, 4 wt%, or 5 wt% to half of the fully formulated coating (48.75 g, 48 g, or 47.5 g). The mixture was gently blended for 60 seconds at medium speed (approximately 800-1000 RPM) using a paddle mixer. The remaining half of the coating formulation (48.75 g, 48 g, or 47.5 g) was then added to the mixture, followed by additional mixing using the same mixing procedure previously described. The resulting coating formulation was then applied to the target substrate.

[0083] Example 7. Preparation of Iron Substrate, Coating Application, Scribing and Testing
[0084] SSPC-SP3 CRS steel substrates were prepared by grinding the substrate using a four-way 80-grit belt sander. The substrates were then cleaned with acetone using a lint-free cloth. Compressed air was then blown across the substrate to remove any remaining dust particles. SSPC-SP6 and SSPC-SP10 substrates were obtained as blasted. These substrates were simply cleaned using acetone and a lint-free cloth. Compressed air was then blown across the substrate to remove any remaining dust particles.

[0085] One-component waterborne epoxy-amine adduct formulations according to embodiments herein were applied via a gravity-fed conventional spray gun with a 1.8 mm nozzle and 60 psi air pressure. The topcoat was applied via a gravity-fed conventional spray gun using the same settings. Generally, the tested coating systems, whether one, two, or three coats, were allowed to cure for 7 days after coating application before being damaged. Each panel was damaged by scribing using a 156 μm van Laar scribe tool and a 500 μm Sikkens-type scribe tool attached to an Erichsen Model 639 panel scratcher. The scribes were 1 inch and 2 inches long, respectively. The panels were allowed to equilibrate at room temperature for 24 hours. The uncoated areas of the panels were sealed using clear polyester sealing tape. The panels were then subjected to ASTM B117 testing for up to 2000 hours. After ASTM B117 testing, CRS panels were evaluated for adhesion loss as outlined in ASTM D1654, Procedure A, Method 2. Loosely adhered coatings were removed using a rounded spatula held perpendicular to the panel surface and parallel to the scribe. A sliding caliper was used to measure adhesion loss at six points along the scribe. Three panels were evaluated for each formulation tested at each exposure duration, and the average of all measurements was reported.

[0086] Example 8. Aluminum Substrate Preparation, Coating Application, Scribing and Testing
[0087] Aluminum 2024-T3 substrates were prepared by cleaning with acetone using a lint-free cloth, followed by blowing compressed air across the surface to remove any remaining dust particles prior to application. A one-component waterborne epoxy-amine formulation was applied via a gravity-fed conventional spray gun with a 1.8 mm nozzle and 60 psi air pressure. The coating systems to be tested were allowed to cure for 7 days at ambient conditions before damage. Each panel was damaged by scribing with a 500 μm Sikkens-type scribe tool attached to an Erichsen Model 639 panel scratcher. Each panel received one scribe measuring 2.5 inches in length. After damage, the panels were allowed to equilibrate at room temperature for 24 hours, and all uncoated areas were sealed using clear polyester sealing tape and then subjected to ASTM B117 testing within 1500 hours. After ASTM B117 testing, the panels were evaluated for adhesion loss as outlined in ASTM D1654, Procedure A, Method 2. A round spatula held perpendicular to the panel surface and parallel to the scribe was used to remove loosely adhered coatings. Representative images of the resulting adhesion loss were obtained.

[0088] Example 9. Concrete Substrate Preparation, Coating Application, Scribing and Testing
[0089] Concrete substrates were prepared by blowing compressed air across the substrate to remove dust particles. A one-component waterborne epoxy-amine formulation was applied via a gravity-fed conventional spray gun with a 1.8 mm nozzle and 60 psi air pressure and allowed to cure for 7 days before scratching. Each panel was scratched using a razor blade mounted on an Erichsen Model 639 panel scratcher. The scribe was 1 inch long with 90-degree intersecting lines, creating an X pattern. A 2-inch diameter, 3-inch high plastic cylinder was adhered to the surface of the panel, and immediately after scratching, silicone caulk was used to surround the damaged area. The panels were then allowed to equilibrate at room temperature for 24 hours. After this period, 100 ml of water was added to the cylinder and the open end of the cylinder was covered. After 7 days of immersion, the water was discarded, the cylinder was removed, and the samples were allowed to dry for 24 hours. The adhesion of the coating around the scribed area of the panel was then evaluated by applying pressure-sensitive adhesive tape across the scribed area and quickly removing the tape. The panels were then photographed to document evidence of adhesion loss.

[0090] Example 10. Wood Substrate Preparation, Coating Application, Scribe and Testing
[0091] Wood substrates were prepared by sanding with 80-grit sandpaper, both with and without wood grain, followed by the use of compressed air to remove dust particles. One-component water-based epoxy-amine formulations were applied via a gravity-fed conventional spray gun with a 1.8 mm nozzle and 60 psi air pressure and allowed to cure for 7 days before marring. Each panel was scratched using a razor blade mounted on an Erichsen Model 639 panel scratcher. The scribe was 1 inch long with 90-degree intersecting lines, creating an X pattern. After marring, the panels were allowed to equilibrate at room temperature for 24 hours. The panels were then submerged in water and allowed to soak for 8 hours, then removed from the water and placed in a freezer for 16 hours. Finally, the panels were removed from the freezer, thawed, and dried for 72 hours. The panels were then imaged using a camera and optical microscope to document changes in film properties.

[0092] In this manner, one-component waterborne resin systems containing epoxy amine adduct resin systems can be imparted with improved properties related to adhesive effectiveness and corrosion resistance to substrates (e.g., steel, aluminum, wood, concrete, other metals, etc.). The improved properties are realized upon degradation of a certain amount of a protective material comprising a one-component waterborne resin system incorporating microcapsules loaded with a healing agent. Specifically, degradation of the protective material causes rupture of the microcapsules at the degradation site, resulting in the release of the healing agent. A component of the healing agent then reacts with one component of the protective material to improve at least the adhesion and corrosion resistance of the protective material to the substrate. These improvements are advantageous in terms of improving the protective qualities of the protective material with respect to the surface it is intended to protect. These improvements are also advantageous given the growing demand for waterborne coatings by reducing the impact of the application of such coatings on the environment (e.g., reduced VOCs) and reducing health, safety, and environmental risks otherwise associated with the use of more traditional solvent-borne coatings. Thus, by improving the protective qualities of water-based coatings, as disclosed herein, the use of such water-based coatings can be increased compared to traditional solvent-borne coatings, which in turn can be advantageous for the reasons discussed above.

[0093] A technical effect of improving the protective qualities of waterborne coatings is realized by certain components, including a healing agent, and waterborne coating formulations as disclosed herein. Specifically, the technical effect is realized through the release of the healing agent through a reaction (e.g., crosslinking) between the free amines corresponding to the epoxy-amine adduct resin system of the cured protective material and the epoxy resin included as part of the healing agent. The technical effect is further realized by the inclusion of a polar aprotic solvent as part of the healing agent, which allows for expansion of the cured epoxy amine adduct material and, in turn, allows for newly established entanglement of the oligomeric resin component of the epoxy amine adduct resin system of the protective material.

[0094] While certain embodiments have been shown and described herein, those skilled in the art will recognize that a wide variety of alternative and/or equivalent embodiments or examples designed to achieve the same purpose may be substituted for the embodiments shown and described without departing from the scope. Those skilled in the art will readily recognize that the embodiments may be implemented in a wide variety of ways. This application is intended to cover any modifications or variations of the embodiments discussed herein. Accordingly, it is manifestly intended that the embodiments be limited only by the claims and equivalents thereof.
[Item 1]
One-component water-based resin systems, and
A self-healing coating formulation comprising a healing agent encapsulated within microcapsules.
[Item 2]
2. The self-healing coating formulation of claim 1, wherein the microcapsules further comprise a polymeric shell wall.
[Item 3]
3. The self-healing coating formulation of claim 2, wherein the polymeric shell wall is composed of one or more of urea formaldehyde, melamine formaldehyde, polyacrylate, polyurea, and polyurethane.
[Item 4]
The repair agent is
epoxy resin,
polar aprotic solvents, and
Alkoxysilane
2. The self-healing coating formulation of claim 1, further comprising:
[Item 5]
5. The self-healing coating formulation of claim 4, wherein the alkoxysilane is one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methacrylpropyltrimethoxysilane, and methacrylpropyltriethoxysilane.
[Item 6]
the alkoxysilane is a glycidylalkoxysilane,
The glycidylalkoxysilane is one or both of 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane;
Item 6. The self-healing coating formulation according to item 5.
[Item 7]
5. The self-healing coating formulation of claim 4, wherein the polar aprotic solvent is one or more of benzyl acetate, ethyl phenylacetate, phenyl acetate, octyl acetate, and nitrobenzene.
[Item 8]
5. The self-healing coating formulation of claim 4, wherein the epoxy resin further comprises bisphenol A-(epichlorohydrin).
[Item 9]
2. The self-healing coating formulation of claim 1, wherein the one-component water-based resin system further comprises an epoxy amine adduct resin system.
[Item 10]
Item 10. The self-healing coating formulation of item 1, wherein the microcapsules are of an average diameter of 25 microns or less.
[Item 11]
2. The self-healing coating formulation of claim 1, which when applied to a substrate hardens to form a protective coating or sealant.
[Item 12]
1. A method for protecting a substrate, comprising:
applying a formulation to the substrate, the formulation comprising a one-component water-based resin system and a healing agent encapsulated in microcapsules, the formulation hardening to form a protective material upon application to the substrate;
Degradation of the protective material results in rupture of the microcapsules at the degradation site and release of the healing agent.
method.
[Item 13]
the one-component waterborne resin system further comprises an epoxy amine adduct resin system;
the repair agent further comprises an epoxy resin, a polar aprotic solvent, and an alkoxysilane;
Item 13. The method according to item 12.
[Item 14]
14. The method of claim 13, wherein the release of the healing agent in response to microcapsule rupture promotes non-covalent entanglement of the oligomeric components of the epoxy amine adduct resin system and a covalent crosslinking reaction between the epoxy resin present in the healing agent and available amine groups in the protective material.
[Item 15]
14. The method of claim 13, wherein the epoxy resin further comprises bisphenol A-(epichlorohydrin).
[Item 16]
14. The method of claim 13, wherein the polar aprotic solvent is one or more of phenyl acetate, benzyl acetate, ethyl phenylacetate, octyl acetate, and nitrobenzene.
[Item 17]
Item 14. The method of item 13, wherein the alkoxysilane is one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methacrylpropyltrimethoxysilane, and methacrylpropyltriethoxysilane.
[Item 18]
the microcapsules further comprise a polymeric shell wall comprised of one or more of urea formaldehyde, melamine formaldehyde, polyacrylate, polyurea, and polyurethane;
The microcapsules have a diameter of 10 to 50 microns.
Item 13. The method according to item 12.
[Item 19]
19. The method of claim 18, wherein the microcapsules have a diameter of less than 25 microns.
[Item 20]
13. The method of claim 12, wherein the degradation further comprises one or more of mechanical breakage, scratches, cracks, cuts, or other loss of integrity of the protective material.
[Item 21]
13. The method of claim 12, wherein rupture of the microcapsules and release of the healing agent at the degradation site reduces corrosion by limiting the ingress of moisture and electrolytes compared to the protective material lacking the encapsulated healing agent.
[Item 22]
13. The method of claim 12, wherein the substrate is one of steel, aluminum, concrete, and wood.
[Item 23]
applying the formulation to the substrate,
coating the substrate with a primer comprising an inorganic coating binder to form a first coating layer;
coating the primer with an organic coating comprising an organic coating binder to form a second coating layer;
13. The method of claim 12, further comprising applying the formulation over the second coating layer as an overcoat layer.
[Item 24]
24. The method of claim 23, wherein the primers further comprise zinc-rich primers.
[Item 25]
24. The method of claim 23, wherein the primer further comprises microcapsules that encapsulate the repair agent.
[Item 26]
24. The method of claim 23, wherein the inorganic coating binder is a silicate binder.
[Item 27]
24. The method of claim 23, wherein the organic coating binder is an epoxy resin cured with one or more of the following curing agents: amines, polyamines, anhydrides, aminosiloxanes, imidazoles, polyamides, ketamine, modified amines that are reaction products of amines and other compounds, mercaptans and polymercaptans, polysulfides, thiols, boron trifluoride amine complexes, organic acid hydrazides, light and ultraviolet curing agents.
[Item 28]
1. A method for maintaining adhesion of a protective material to a substrate after degradation of the protective material, comprising:
applying to the substrate a water-based epoxy coating formulation including a healing agent encapsulated in microcapsules, the water-based epoxy coating formulation hardening upon its application to the substrate to form the protective material.
degradation of the protective material results in rupture of the microcapsules at the degradation site and release of the healing agent, thereby maintaining adhesion of the protective material to the substrate;
method.
[Item 29]
29. The method of claim 28, wherein the degradation of the protective material is due to one or more of mechanical breakage, scratches, cracks, cuts, or other loss of integrity of the protective material.
[Item 30]
29. The method of claim 28, wherein the water-based resin system is an epoxy amine adduct resin system and the healing agent further comprises an epoxy resin, a polar aprotic solvent, and an alkoxysilane.
[Item 31]
31. The method of claim 30, wherein the rupture of the microcapsules and release of the healing agent maintains adhesion of the protective material to the substrate by a chemical reaction between the amine groups corresponding to the epoxy amine adduct resin system and the epoxy resin of the healing agent, and swelling of the protective material with the aprotic solvent, which allows entanglement between the oligomeric resin components of the protective material.
[Item 32]
31. The method of claim 30, wherein the epoxy resin further comprises bisphenol A-(epichlorohydrin).
[Item 33]
31. The method of claim 30, wherein the polar aprotic solvent is one or more of phenyl acetate, benzyl acetate, ethyl phenylacetate, octyl acetate, and nitrobenzene.
[Item 34]
31. The method of claim 30, wherein the alkoxysilane is one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methacrylpropyltrimethoxysilane, and methacrylpropyltriethoxysilane.
[Item 35]
the microcapsules further comprise a polymeric shell wall comprised of one or more of urea formaldehyde, melamine formaldehyde, polyacrylate, polyurea, and polyurethane;
the microcapsules have a diameter of less than 25 microns;
Item 29. The method according to item 28.

Claims (15)

a one-component water-based resin system and a restorative agent encapsulated in microcapsules;
the one-component waterborne resin system comprises an epoxy amine adduct resin ;
the microcapsules comprising a polymeric shell wall;
A self-healing coating formulation, wherein the healing agent comprises an epoxy resin, a polar aprotic solvent, and an alkoxysilane . 10. The self-healing coating formulation of claim 1, wherein the polymeric shell wall is composed of one or more of urea formaldehyde, melamine formaldehyde, polyacrylate, polyurea, and polyurethane, and/or the microcapsules are of an average diameter of 25 microns or less. the epoxy resin contains bisphenol A-(epichlorohydrin);
the polar aprotic solvent is one or more of benzyl acetate, ethyl phenylacetate, phenyl acetate, octyl acetate, and nitrobenzene;
2. The self-healing coating formulation of claim 1, wherein the alkoxysilane is one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methacrylpropyltrimethoxysilane, and methacrylpropyltriethoxysilane. the alkoxysilane is a glycidylalkoxysilane,
The glycidylalkoxysilane is one or both of 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane;
4. The self-healing coating formulation of claim 3. The self-healing coating formulation of claim 1, which when applied to a substrate, hardens to form a protective coating or sealant. 1. A method for protecting a substrate, comprising:
applying a formulation to the substrate, the formulation comprising a one-component water-based resin system and a healing agent encapsulated in microcapsules, the formulation hardening to form a protective material upon application to the substrate;
degradation of the protective material results in rupture of the microcapsules at the degradation site and release of the healing agent;
the one-component waterborne resin system comprises an epoxy amine adduct resin;
the microcapsules comprising a polymeric shell wall;
the repair agent comprises an epoxy resin, a polar aprotic solvent, and an alkoxysilane ;
method. the epoxy resin contains bisphenol A-(epichlorohydrin);
the polar aprotic solvent comprises one or more of phenyl acetate, benzyl acetate, ethyl phenylacetate, octyl acetate, and nitrobenzene;
7. The method of claim 6, wherein the alkoxysilane comprises one or more of 3 -glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methacrylpropyltrimethoxysilane, and methacrylpropyltriethoxysilane. 7. The method of claim 6, wherein the release of the healing agent in response to microcapsule rupture promotes non-covalent entanglement of the oligomeric components of the epoxy amine adduct resin and a covalent cross-linking reaction between the epoxy resin present in the healing agent and available amine groups in the protective material. the polymeric shell wall is comprised of one or more of urea formaldehyde, melamine formaldehyde, polyacrylate, polyurea, and polyurethane;
The microcapsules have a diameter of 10 to 50 microns.
The method of claim 6. 7. The method of claim 6, wherein the degradation comprises one or more of mechanical failure, scratching, cracking, nicking, or other loss of integrity of the protective material; and/or the rupture of the microcapsules and release of the healing agent at the degradation site reduces corrosion by limiting the ingress of moisture and electrolytes compared to the protective material lacking the healing agent; and/or the substrate is one of steel, aluminum, concrete, and wood. applying the formulation to the substrate,
coating the substrate with a primer comprising an inorganic coating binder to form a first coating layer , the primer further comprising a zinc-rich primer and/or the primer further comprising the microcapsules encapsulating the healing agent;
coating the primer with an organic coating comprising an organic coating binder to form a second coating layer, wherein the inorganic coating binder is a silicate binder or the organic coating binder is an epoxy resin cured with one or more of the following curing agents: amines, polyamines, anhydrides, aminosiloxanes, imidazoles, polyamides, ketamines, modified amines that are reaction products of amines and other compounds, mercaptans and polymercaptans, polysulfides, thiols, boron trifluoride amine complexes, organic acid hydrazides, light and ultraviolet light curing agents;
and applying said formulation over said second coating layer as an overcoat layer. 1. A method for maintaining adhesion of a protective material to a substrate after degradation of the protective material, comprising:
applying to the substrate a water-based epoxy coating formulation comprising a healing agent encapsulated in microcapsules, the water-based epoxy coating formulation hardening upon its application to the substrate to form the protective material, wherein degradation of the protective material results in rupture of the microcapsules at the degradation sites and release of the healing agent, thereby maintaining adhesion of the protective material to the substrate;
the microcapsules comprising a polymeric shell wall;
The method , wherein the waterborne epoxy coating formulation comprises a waterborne resin system, the waterborne resin system being an epoxy amine adduct resin , and the healing agent comprises an epoxy resin, a polar aprotic solvent, and an alkoxysilane. 13. The method of claim 12, wherein the degradation of the protective material results from one or more of mechanical breaking, scratching, cracking, nicking, or other loss of integrity of the protective material, or the rupture of the microcapsules and release of the healing agent maintains adhesion of the protective material to the substrate by a chemical reaction between amine groups corresponding to the epoxy amine adduct resin and the epoxy resin of the healing agent, and swelling of the protective material with the aprotic solvent, which allows entanglement between oligomeric resin components of the protective material. The method of claim 12, wherein the epoxy resin comprises bisphenol A-(epichlorohydrin), and/or the polar aprotic solvent comprises one or more of phenyl acetate, benzyl acetate, ethyl phenylacetate, octyl acetate, and nitrobenzene, and/or the alkoxysilane comprises one or more of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methacrylpropyltrimethoxysilane, and methacrylpropyltriethoxysilane. the polymeric shell wall is comprised of one or more of urea formaldehyde, melamine formaldehyde, polyacrylate, polyurea, and polyurethane;
the microcapsules have a diameter of less than 25 microns;
The method of claim 12.