Conjugated polymer compositions, articles thereof, and methods thereof

Abstract

The present disclosure provides compositions, articles thereof, and methods for forming the compositions. In at least one embodiment, the composition comprises: (1) an epoxy; (2) an amino or amide curing agent; (3) polyaniline; (4) a dopant selected from triazolyl, thiazolyl, quinolinyl, salicylate, benzoate, glycolate, phosphate, sulfonate, or a combination thereof; and (5) a pigment selected from titanium dioxide, silica, talc, mica, aluminum stearate, or a combination thereof. The polyaniline plus the dopant constitutes 6% or less by weight of the total volume of the composition. The present disclosure also provides a substrate having the composition disposed thereon. In at least one embodiment, the method comprises introducing an acid form of polyaniline into a hydroxide to form a polyaniline hydroxide. The method comprises introducing a dopant into the polyaniline hydroxide to form a doped polyaniline.

Description

[Technical Field]

[0001] The present disclosure provides compositions, articles thereof, and methods of forming the compositions. [Background technology]

[0002] Organic coatings are an efficient way to protect metal substrates from corrosion and also provide aesthetic appeal. Paints and primers form the exterior coating systems for automobiles and aircraft.

[0003] Paint alone does not provide a durable coating for most metals because paint easily peels off the metal when applied directly to the surface. To prevent this, a primer is used. Primers are designed to fill microscopic gaps in the substrate and provide corrosion protection and adhesion. Paint bonds easily with the primer, so it adheres much better when applied over it. Without a primer, most coatings on metals will begin to peel and corrode when exposed to the atmosphere.

[0004] Even when defects are not present, sufficient ions can penetrate the coating and cause corrosion at the metal interface. Furthermore, defects can be caused by physical means, such as impacts from sand particles, stones, or scratches, during normal vehicle or equipment maintenance and operation. To inhibit corrosion, corrosion-inhibiting pigments are added to paints / primers and other organic coatings applied to metal surfaces. The most efficient pigments currently in use are those containing chromates (usually strontium chromate) or other salts of heavy metals such as zinc or lead. However, the use of chromates has gradually decreased over time. Furthermore, the corrosion inhibitors present in chromate coatings continually leach from the coating, resulting in a very limited service life for the coating. Summary of the Invention [Problem to be solved by the invention]

[0005] There is a need for new and improved compositions, articles having the compositions, and methods of forming the compositions. [Means for solving the problem]

[0006] The present disclosure provides compositions, articles thereof, and methods of forming the compositions.

[0007] In at least one embodiment, the composition comprises: (1) an epoxy; (2) an amino or amido curing agent; (3) a polyaniline; (4) a dopant selected from triazolyl, thiazolyl, quinolinyl, salicylate, benzoate, glycolate, phosphate, or a combination thereof; and (5) a pigment selected from titanium dioxide, silica, talc, mica, aluminum stearate, or a combination thereof, wherein the polyaniline plus the dopant constitutes 6% or less by weight, based on the volume of the composition.

[0008] In at least one embodiment, a substrate has a composition disposed thereon.

[0009] In at least one embodiment, the method comprises introducing an acid form of polyaniline into a hydroxide to form a neutral polyaniline or polyaniline base. The method comprises introducing a dopant to the polyaniline base to form a doped polyaniline. The dopant is selected from triazole, thiazole, quinoline, salicylic acid, benzoic acid, glycolic acid, phosphoric acid, or a combination thereof.

[0010] In order that the features of the present disclosure as described above may be understood in detail, a more particular description of the present disclosure briefly summarized above will be had by reference to examples, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical examples of the present disclosure and, therefore, should not be considered as limiting its scope, since the present disclosure may admit of other equally effective examples. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a Bode plot over time for Example 1 (5% PANI-P with Araldite GY 250, Aradur 2973, and 5% reactive diluent), according to one or more embodiments. [Figure 2A] FIG. 10 is a Bode plot over time for Example 3 (Araldite GY 250, Aradur 2973, 5% reactive diluent) but without PANI-P, according to one or more embodiments. [Figure 2B] FIG. 10 is a Bode plot over time for Example 3 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 10% PANI-P) according to one or more embodiments. [Figure 2C] FIG. 10 is a Bode plot over time for Example 3 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 15% PANI-P) according to one or more embodiments. [Figure 2D] FIG. 10 is a Bode plot over time for Example 3 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-P) according to one or more embodiments. [Figure 3A] FIG. 1 is an SVET plot of Example 4 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-B) at "initial" time (5 minutes), according to one or more embodiments. [Figure 3B] FIG. 10 is a SVET plot of Example 4 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-B) at 6 hours of NaCl exposure, according to one or more embodiments. [Figure 3C] FIG. 10 is a SVET plot of Example 4 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-B) at 12 hours of NaCl exposure, according to one or more embodiments. [Figure 3D]FIG. 10 is a SVET plot of Example 4 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-B) at 24 hours of NaCl exposure, according to one or more embodiments. [Figure 4A] 1 is an SVET plot of a PANI-free primer coating at an "initial" time (5 minutes), according to one or more embodiments. [Figure 4B] 1 is an SVET plot of a PANI-free primer coating at 6 hours of NaCl exposure, according to one or more embodiments. [Figure 4C] 1 is an SVET plot of a PANI-free primer coating at 12 hours of NaCl exposure, according to one or more embodiments. [Figure 4D] 1 is an SVET plot of a PANI-free primer coating at 24 hours of NaCl exposure, according to one or more embodiments. [Figure 5A] 1 is a SVET plot of a primer coating with dedoped PANI at an "initial" time (5 minutes), according to one or more embodiments. [Figure 5B] 1 is an SVET plot of a primer coating with dedoped PANI at 6 hours of NaCl exposure, according to one or more embodiments. [Figure 5C] 1 is an SVET plot of a primer coating with dedoped PANI at 12 hours of NaCl exposure, according to one or more embodiments. [Figure 5D] 1 is an SVET plot of a primer coating with dedoped PANI at 24 hours of NaCl exposure, according to one or more embodiments. [Figure 6A] 1 is a Tafel polarization curve plot of a PANI-free primer coating, according to one or more embodiments. [Figure 6B] 1 is a Tafel polarization curve plot of a primer coating including PANI-P, according to one or more embodiments. [Figure 6C] 1 is a Tafel polarization curve plot of a primer coating including PANI-Q, according to one or more embodiments. [Figure 6D] 1 is a Tafel polarization curve plot of a primer coating including PANI-S, according to one or more embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0012] For ease of understanding, where possible, the same reference numerals have been used to indicate identical elements that are common to multiple figures. It is contemplated that elements and features of one example may be beneficially incorporated in other examples without further recitation.

[0013] The present disclosure provides compositions, articles thereof, and methods for forming the compositions. The compositions of the present disclosure include (1) an epoxy, (2) an amino or amide curing agent, (3) a polyaniline, (4) a dopant selected from triazolyl, thiazolyl, quinolinyl, salicylate, benzoate, glycolate, phosphate, or a combination thereof, and (5) one or more pigments selected from titanium dioxide, silica, talc, mica, aluminum stearate, or a combination thereof. The articles of the present disclosure include a substrate and a composition disposed thereon. The method for forming the compositions of the present disclosure can include treating a polyaniline base with a dopant selected from triazole, thiazole, quinoline, salicylate, benzoate, glycolic acid, phosphate, or a combination thereof.

[0014] Polyaniline is a conjugated polymer with alternating C-C single and C-C double bonds along the polymer chain. The π ("pi") electron conjugation extends across the polymer backbone, making these polymers conductive and capable of switchable redox properties. The polymer backbone is positively charged in the oxidized form and can bind negatively charged ions (e.g., negatively charged dopants). This phenomenon is also known as doping. Without being bound by any particular theory, it has been discovered that molecules / ions with corrosion-inhibiting properties can be incorporated as dopants. Due to its redox properties, polyaniline can shift the corrosion potential of the system and passivate the substrate.

[0015] The oxidized ("emeraldine") form of polyaniline can be bound to dopant(s) with corrosion-inhibiting properties. In the presence of a corrosive environment, the polyaniline is reduced, releasing the dopant(s). This chemical change promotes "self-repair" in areas of the substrate where the composition (as a layer / film) is missing or damaged. As corrosion occurs, the corrosion changes the local potential, chemically reducing the polyaniline, which releases the dopant from the polyaniline, which can then localize to exposed substrate defects (as evidenced by SVET scans described below). In other words, the dopant can be released "on demand" as corrosion of a portion of the substrate occurs, rather than being continuously released from the cured composition. Furthermore, the dopant bound to the polyaniline mitigates reactivity issues between "floating" (e.g., unbound) corrosion inhibitors (e.g., thiol-containing corrosion inhibitors) and reactive moieties in epoxies (e.g., epoxide moieties).

[0016] composition The compositions of the present disclosure include: (1) an epoxy; (2) an amino or amide curing agent; (3) a polyaniline; (4) a dopant selected from triazolyl, thiazolyl, quinolinyl, salicylate, benzoate, glycolate, phosphate, or a combination thereof; and (5) one or more pigments selected from titanium dioxide, silica, talc, mica, aluminum stearate, or a combination thereof.

[0017] As used herein, a "composition" may include a component of the composition and / or a reaction product(s) of two or more components of the composition.

[0018] Compositions of the present disclosure may have a volatile organic content of about 300 g / L or less, e.g., about 100 g / L to about 300 g / L, e.g., about 200 g / L to about 250 g / L, as determined by ASTM D 3960-01. Compositions having a volatile organic content of about 300 g / L or less may provide a low volatile organic content, providing an environmentally friendly (e.g., eco-friendly) composition.

[0019] The compositions of the present disclosure may have a volumetric solids content of about 70% or more, for example, 80% or more, for example, about 90% or more, based on the total volume of the composition. The volumetric solids content is calculated for weighing the ingredients and preparing the composition. The total solids content may be determined by evaporating the solvent. A composition having a volumetric solids content of about 70% or more may have a low volatile organic content, resulting in an environmentally compatible (e.g., environmentally friendly) composition.

[0020] The composition of the present disclosure can be disposed on one or more substrates. The composition disposed on the substrate (e.g., as a layer) can be applied to a thickness of about 1 micrometer (μm) to about 100 μm, for example, about 1 μm to about 10 μm, for example, about 10 μm to about 80 μm, for example, about 20 μm to about 60 μm, for example, about 25 μm, about 35 μm, about 45 μm, or about 50 μm. In at least one embodiment, the cured composition, when contacted with a 3.5% NaCl solution, has a thickness of about 10 μm to about 100 μm. 4 Ω~about 10 9 Ω, for example, about 10 6 Ω electrochemical impedance. (This is the resistance of the coating to the penetration of NaCl. It is a measure of barrier protection. Higher values ​​indicate better resistance.)

[0021] The substrate of the present disclosure can be a vehicle component or a wind turbine component (e.g., turbine blade(s) or turbine station(s)). A vehicle comprises any suitable transportation device. Vehicles include, but are not limited to, aircraft, automobiles, boats, motorcycles, satellites, rockets, missiles, and the like, and thus further include manned and unmanned aerial vehicles, manned and unmanned spacecraft, manned and unmanned ground vehicles, manned and unmanned non-ground vehicles, and even manned and unmanned surface and subsurface marine vehicles, objects, and structures.

[0022] A vehicle component may comprise one or more compositions of the present disclosure disposed on one or more surfaces of the vehicle component. The vehicle component may be any component of a vehicle, such as a structural component, for example, a panel or joint of the vehicle, but is not limited to such. Examples of vehicle components include airfoils (e.g., rotor blades), auxiliary power units, aircraft noses, fuel tanks, tail cones, panels, coated lap joints between two or more panels, wing-fuselage assemblies, aircraft structural composites, fuselage body joints, wing rib-to-skin joints, and / or other interior components.

[0023] Epoxy and Amino / Amide Hardeners The compositions of the present disclosure may include one or more epoxies and one or more amino curing agents and / or one or more amide curing agents.

[0024] In at least one embodiment, the composition comprises ((epoxy + amino curing agent) or (epoxy + amide curing agent)) in an amount of about 55% to about 85% by weight, e.g., about 55% to about 75% by weight, or about 65% to about 85% by weight, based on the total volume of the composition.

[0025] In at least one embodiment, the composition comprises one or more epoxies in an amount of about 35% to about 55% by weight, e.g., about 35% to about 45% by weight, or about 40% to about 50% by weight, based on the total volume of the composition. In at least one embodiment, the composition comprises one or more amino curing agents in an amount of about 15% to about 25% by weight, e.g., about 15% to about 20% by weight, or about 18% to about 24% by weight, based on the total volume of the composition. In at least one embodiment, the composition comprises one or more amide curing agents in an amount of about 15% to about 25% by weight, e.g., about 15% to about 20% by weight, or about 18% to about 24% by weight, based on the total volume of the composition.

[0026] Epoxies may include partially cured epoxies, two-component epoxy resins containing epoxy specific additives and catalysts (e.g., HYSOL® EA 956 epoxy resin available from Henkel Corporation, Bay Point, California), two-part systems containing a resin of the present disclosure and a curing agent (e.g., EPOFIX resin available from Struers A / S, Ballerup, Denmark), triglycidyl ethers of aminophenols (e.g., Araldite MY 0500 or MY 0510 from Huntsman Advanced Materials, Monthey, Switzerland), tetrafunctional epoxies such as N,N,N',N'-tetraglycidyl-m-xylylenediamine (e.g., Araldite MY0720 or MY0721 from Huntsman Advanced Materials, Monthey, Switzerland), and mixtures thereof. Epoxies also include difunctional epoxies such as bisphenol A (BisA) or bisphenol F (BisF) based epoxies. Bis-A type epoxy resins can be commercially available as Araldite GY6010 (Huntsman Advanced Materials) or DER 331 available from Dow Chemical Company (Midland, Michigan). Bis-F type epoxy resins are commercially available as Araldite GY281 and GY285 (Huntsman Advanced Materials). Epoxies are durable, making them suitable for thermosetting resins, for example, on the exterior of aircraft. In one or more embodiments, the epoxy is a bisphenol A type epoxy, Araldite GY 250 or GY 9090, available from Huntsman Advanced Materials.

[0027] Amino curing agents include polyaminoamine curing agents (e.g., Aradur 450, Aradur 2973 (Huntsman Advanced Materials, Monthey, Switzerland) and Examples of suitable curing agents include aliphatic polyamine curing agents commercially available from JEFFAMINE Materials (Monthey, Switzerland), polyetheramines having a Tg of about 40°C to about 100°C (e.g., JEFFAMINE® T-403 amine or JEFFAMINE® D-230 amine), ethyleneamines having a Tg of about 110°C to about 125°C (e.g., diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or N-aminoethylpiperazine), alicyclic amines having a Tg of about 145°C to about 175°C (e.g., bis-(p-aminocyclohexyl)methane, diaminocyclohexane, or bis-(dimethyldiaminocyclohexyl)methane), or aromatic amines having a Tg of about 160°C to about 220°C (e.g., methylenedianiline, m-phenylenediamine, or diaminophenyl sulfone).

[0028] Amide curing agents include Aradur 360 (a polyamidoamine curing agent commercially available from Huntsman Advanced Materials, Monthey, Switzerland), or polyamides or amidoamines with a Tg of about 40°C to about 100°C (e.g., VERSAMID® 125 polyamide or GENAMID® 490 amidoamine).

[0029] Polyaniline and dopants The compositions of the present disclosure may comprise one or more polyanilines and one or more dopants. In at least one embodiment, the composition comprises polyaniline plus dopant in an amount of about 0.1% to about 6% by weight, e.g., about 0.5% to about 3% by weight, or about 3% to about 5.5% by weight, based on the total volume of the composition. The composition may comprise polyaniline plus dopant in an amount of about 1% to about 25% by weight, e.g., about 5% to about 15% by weight, or about 15% to about 25% by weight, based on the pigment volume concentration of the composition. As used herein, "pigment volume concentration" refers to the ratio of the volume of pigment to the volume of all nonvolatile materials (total solids) present in the coating composition. Pigment volume concentration may be determined using ASTM D 2371-19 and ASTM D 2698-05 (Reapproved 2015).

[0030] Pigments include TiO2, talc, mica, silica, and Al stearate, or combinations thereof.

[0031] In at least one embodiment, the composition comprises polyaniline plus dopant in an amount of about 0.1% to about 6% by weight, such as about 2% to about 4% by weight, based on the total volume of the composition.

[0032] In at least one embodiment, the composition comprises polyaniline plus dopant in an amount of from about 1% to about 25%, such as from about 10% to about 20%, based on the pigment volume concentration of the composition.

[0033] The molar ratio of the dopant to the aniline units of the polyaniline can be from about 0.1:1 to about 1:1, such as from about 0.3:1 to about 1:1, such as from about 0.5:1 to about 1:1, for example about 1:1.

[0034] The dopant may be selected from triazolyl, thiazolyl, quinolinyl, salicylate, benzoate, glycolate, phosphate, or combinations thereof.

[0035] In at least one embodiment, the triazolyl is selected from a benzotriazole, a triazole carboxylic acid, or a benzotriazole sulfonic acid.

[0036] In at least one embodiment, the thiazolyl is selected from one or more of benzothiazole, thiazolecarboxylic acid, or mercaptobenzothiazole.

[0037] In at least one embodiment, the quinolinyl is selected from 8-hydroxyquinoline or mercaptoquinoline.

[0038] In at least one embodiment, the salicylate is selected from salicylic acid, hydroxybenzoic acid, or salts thereof.

[0039] In at least one embodiment, the benzoate is selected from benzoate, benzoic acid, methylbenzoate, or salts thereof.

[0040] In at least one embodiment, the glycolate is selected from glycolate or thioglycolate.

[0041] In at least one embodiment, the phosphate is selected from phosphoric acid or a salt thereof.

[0042] The polyaniline of the present disclosure may be formed using aniline and phosphoric, sulfuric, or sulfonic acids.

[0043] pigment In at least one embodiment, the composition of the present disclosure comprises a pigment selected from titanium dioxide, silica, talc, mica, aluminum stearate, or a combination thereof.

[0044] The pigments of the present disclosure can impart opacity to the composition, for example, a composition including the pigment(s) can be coated onto a substrate to render the coated substrate opaque.

[0045] In at least one embodiment, the composition comprises each of titanium dioxide, talc, mica, silica, and aluminum stearate. For example, the composition may comprise titanium dioxide in an amount of about 5% to about 30%, e.g., about 10% to about 20%, e.g., about 15%, based on the pigment volume concentration of the composition. The composition may comprise titanium dioxide in an amount of about 5% to about 12% by weight, e.g., about 6% to about 10% by weight, e.g., about 7% to about 9% by weight, based on the total volume of the composition. The composition may comprise talc in an amount of about 5% to about 30%, e.g., about 20% to about 30%, e.g., about 25%, based on the pigment volume concentration of the composition. The composition may comprise talc in an amount of about 1% to about 12% by weight, e.g., about 2% to about 10% by weight, e.g., about 3% to about 6% by weight, based on the total volume of the composition. The composition may contain mica in an amount of about 5% to about 30%, for example, about 20% to about 30%, for example, about 25%, based on the pigment volume concentration of the composition. The composition may contain mica in an amount of about 1% to about 12%, for example, about 2% to about 10%, for example, about 3% to about 6% by weight, based on the total volume of the composition. The composition may contain silica in an amount of about 5% to about 30%, for example, about 20% to about 30%, for example, about 28%, based on the pigment volume concentration of the composition. The composition may contain silica in an amount of about 0.1% to about 30%, for example, about 7% to about 20%, for example, about 9% to about 13% by weight, based on the total volume of the composition.

[0046] The composition may comprise aluminum stearate in an amount of about 1% to about 5%, for example about 1% to about 3%, for example about 2%, based on the pigment volume concentration of the composition.The composition may comprise aluminum stearate in an amount of about 0.1% to about 1% by weight, for example about 0.1% to about 0.5% by weight, for example about 0.3% to about 0.8% by weight, based on the total volume of the composition.

[0047] Compositions and layers of compositions In at least one embodiment, a method for forming a composition includes mixing (1) an epoxy, (2) an amino or amide curing agent, (3) a polyaniline, (4) a dopant selected from triazolyl, thiazolyl, quinolinyl, salicylate, benzoate, glycolate, phosphate, or a combination thereof, and (5) one or more pigments selected from titanium dioxide, silica, talc, mica, aluminum stearate, or a combination thereof to form a composition. The mixing may include diffusion and / or active mixing (e.g., mixing with a stirrer). The method may include disposing (e.g., depositing) the composition on a substrate to form a layer including the composition. The method may include curing the composition. The method may include dissolving one or more components of the composition in a solvent prior to mixing. The solvent may be xylene, toluene, dimethyl sulfoxide, water, or a mixture thereof.

[0048] The substrate can be a metal substrate made from aluminum, aluminum alloy, nickel, iron, iron alloy, steel, titanium, titanium alloy, copper, copper alloy, or a mixture thereof. The substrate can be a "bare" substrate that has no plating (e.g., non-plated metal), no conversion coating, and / or no corrosion protection between the substrate and the composition. Additionally or alternatively, the substrate can include surface oxidation. Thus, the composition can be disposed directly on the substrate and / or directly on a surface oxide layer on the surface of the substrate.

[0049] A secondary layer may optionally be disposed (e.g., deposited) on the composition (e.g., disposed on a substrate). The secondary layer may be an organic material (e.g., an organic composition) configured to be disposed (e.g., adhered) on the composition. The secondary layer may comprise a paint, a topcoat, a polymer coating (e.g., an epoxy coating and / or a urethane coating), a polymeric material. In at least one embodiment, the secondary layer comprises a polymer, a resin, a thermosetting polymer, a thermoplastic polymer, an epoxy, a lacquer, a polyurethane, a polyester, or a combination thereof. The secondary layer may further comprise a pigment, a binder, a surfactant, a diluent, a solvent, a particulate (e.g., a mineral filler), a fiber (e.g., carbon, aramid, and / or glass fiber), or a combination thereof.

[0050] The thickness of the composition (e.g., a layer containing the composition) can be used to adjust one or more of: (1) corrosion resistance, (2) barrier properties, and (3) electrochemical resistance of the cured composition disposed on a substrate.

[0051] The composition of the present disclosure can be disposed on (e.g., disposed onto) a surface, such as a surface of a vehicle part, by any suitable method, such as dipping, spraying, brush coating, spin coating, roll coating, doctor blade coating, or a combination thereof. After application to the vehicle part surface, the composition can be cured at ambient temperature for a period of time. For example, the composition can be deposited on the vehicle part. Once deposited, the composition can be heated to cure the composition. Elevated temperatures can be used to accelerate the curing process. Heating promotes evaporation of one or more solvents (if present) in the composition, such as xylene, toluene, and / or water.

[0052] Curing the composition can include raising the temperature of the composition to a peak cure temperature and maintaining the peak cure temperature for about 1 second to about 48 hours, e.g., about 1 hour to about 10 hours. The peak cure temperature can be generally from room temperature to about 100°C, e.g., from about 50°C to about 90°C, e.g., 50°C, 60°C, 70°C, 80°C, or 90°C. The cure time can be from about 4 hours to about 200 hours at ambient temperature (20-30°C).

[0053] Disposition (e.g., deposition) of the composition on a substrate can be achieved by spin-coating the composition onto the surface of the substrate, e.g., vehicle part, at a speed of about 100 rpm to about 4,000 rpm, e.g., about 500 rpm to about 2,000 rpm, e.g., about 500 rpm, about 1,000 rpm, about 1,500 rpm, about 2,000 rpm.

[0054] Alternatively, disposing the composition on the substrate is accomplished by spraying the composition onto the surface of the substrate, e.g., vehicle part, using any suitable composition spraying device, or by brushing the composition onto the surface of the substrate, or by immersing the substrate in the composition.

[0055] Thickness of the Cured Composition Coating thickness can be measured with an ELCOMETER or DEFELSKO eddy current based probe.

[0056] Electrochemical Impedance Spectroscopy (EIS) EIS uses a variable frequency AC source to study the change in impedance of a sample at different frequencies. Similar to a resistor, impedance is the delay between the applied AC current and the measured voltage change. Electrical circuit components respond in a frequency-dependent manner, which can be used to identify specific properties of the coating being measured. A true ohmic resistor responds identically to direct current (DC) and alternating current (AC) sources and therefore does not exhibit a frequency-dependent resistance response. Capacitors (and more complex electrical components) have a frequency-dependent response; that is, they exhibit very high impedance at low frequencies but low electrical impedance at high frequencies. In analyzing EIS data, a predictive model, known as an equivalent circuit model, is constructed from real and simulated electrical components to closely approximate the sample system. The calculated impedance spectrum of the model is then compared to the measured spectrum.

[0057] Application of the composition The compositions of the present disclosure can be deposited on the surface of a substrate, such as a vehicle part. Vehicle parts include structural parts, such as panels or joints of aircraft, automobiles, ships, etc. Examples of vehicle parts include airfoils (e.g., rotor blades), fuselages, wings, auxiliary power units, aircraft noses, fuel tanks, tail cones, panels, coated lap joints between two or more panels, wing-fuselage assemblies, aircraft structural composites, fuselage body joints, wing rib-to-skin joints, and / or other internal parts.

[0058] Compared to conventional coatings, the compositions and methods of the present disclosure result in some degree of reduced corrosion inhibitor leaching over time because the corrosion inhibitor dopant is bound to the polyaniline (e.g., emeraldine form of polyaniline) and can be released from the polyaniline in response to a corrosive environment.

[0059] Aspects The present disclosure provides, inter alia, the following aspects, each of which may be considered to include any alternative aspects. Clause 1. A composition comprising: Epoxy, Amino or amide hardeners, polyaniline, a dopant selected from triazolyl, thiazolyl, quinolinyl, salicylate, benzoate, glycolate, phosphate, or combinations thereof; and a pigment selected from titanium dioxide, silica, talc, mica, aluminum stearate, or a combination thereof; A composition wherein the polyaniline plus dopant constitutes 6% or less by weight based on the volume of the composition. Clause 2. The composition of clause 1, wherein the polyaniline is emeraldine form of polyaniline. Clause 3. The composition of clause 1 or 2, having a volatile organic content of 300 g / L or less. Clause 4. The composition of any one of clauses 1 to 3, having a volumetric solids content of about 70% or greater, based on the total volume of the composition, as determined by weighing the ingredients and preparing the composition. The total solids content may be determined by evaporating the solvent. Clause 5. The composition of any one of clauses 1 to 4, comprising (epoxy + amino and / or amide curing agent) in an amount of about 45% to about 85% by weight, based on the total volume of the composition. Clause 6. The composition of any one of clauses 1 to 5, comprising one or more epoxies in an amount of about 40% to about 55% by weight, based on the total volume of the composition. Clause 7. The composition of any one of clauses 1 to 6, comprising an amino curing agent in an amount of about 15% to about 21% by weight, based on the total volume of the composition. Clause 8. The composition of any one of clauses 1 to 7, comprising an amide curing agent in an amount of about 15% to about 21% by weight, based on the total volume of the composition. Clause 9. The composition of any one of clauses 1 to 8, wherein the epoxy is a bisphenol A type epoxy or a bisphenol F type epoxy. Clause 10. The composition of any one of clauses 1 to 9, comprising polyaniline plus dopant in an amount of about 0.1% to about 6% by weight, based on the total volume of the composition. Clause 11. The composition of any one of clauses 1 to 10, comprising polyaniline plus dopant in an amount of about 1% to about 25%, based on the pigment volume concentration of the composition. Clause 12. The composition of any one of clauses 1 to 11, wherein the molar ratio of dopant to aniline units of the polyaniline is from about 0.3:1 to about 1:1. Clause 13. The composition of any one of clauses 1 to 12, wherein the dopant is a triazolyl selected from a benzotriazole, a triazole carboxylic acid, or a benzotriazole sulfonic acid. Clause 14. The composition of any one of clauses 1 to 13, wherein the dopant is a thiazolyl selected from one or more of benzothiazole, thiazolecarboxylic acid, or mercaptobenzothiazole. Clause 15. The composition of any one of clauses 1 to 14, wherein the dopant is a quinolinyl selected from 8-hydroxyquinoline or mercaptoquinoline. Clause 16. The composition of any one of clauses 1 to 15, wherein the dopant is a salicylate selected from salicylic acid, hydroxybenzoic acid, or salts thereof. Clause 17. The composition of any one of clauses 1 to 16, wherein the dopant is a benzoate selected from benzoic acid, methylbenzoic acid, or salts thereof. Clause 18. The composition of any one of clauses 1 to 17, wherein the dopant is a glycolate selected from glycolate or thioglycolate. Clause 19. The composition of any one of clauses 1 to 18, wherein the dopant is a phosphate selected from phosphoric acid or salts thereof. Clause 20. The composition of any one of clauses 1 to 19, comprising a pigment in an amount of about 10% to about 50% by weight, based on the total volume of the composition. Clause 21. The composition of any one of clauses 1 to 20, comprising a pigment in an amount of about 20% to about 40%, based on the total volume of the composition. Clause 22. The composition of any one of clauses 1 to 21, comprising titanium dioxide, silica, talc, mica, and aluminum stearate. Clause 23. The composition of any one of clauses 1 to 22, comprising titanium dioxide in an amount of about 10% to about 25%, based on the pigment volume concentration of the composition, or about 5% to about 14% by weight, based on the total volume of the composition. Clause 24. The composition of any one of clauses 1 to 23, comprising talc in an amount of about 15% to about 30% based on the pigment volume concentration of the composition, or about 6% to about 12% by weight based on the total volume of the composition. Clause 25. The composition of any one of clauses 1 to 24, comprising mica in an amount of about 5% to about 30%, based on the pigment volume concentration of the composition, or in an amount of about 2% to about 12% by weight, based on the total volume of the composition. Clause 26. The composition of any one of clauses 1 to 25, comprising silica in an amount of about 20% to about 30% based on the pigment volume concentration of the composition, or about 8% to about 13% by weight based on the total volume of the composition. Clause 27. The composition of any one of clauses 1 to 26, comprising aluminum stearate in an amount of about 1% to about 3%, based on the pigment volume concentration of the composition, or in an amount of about 0.1% to about 0.6% by weight, based on the total volume of the composition. Clause 28. A substrate having disposed thereon the composition of any one of clauses 1 to 27. Clause 29. The substrate of clause 28, wherein the cured composition thereon has a thickness of about 5 μm and about 100 μm. Clause 30. When the hardening composition comes into contact with a 3.5% NaCl solution, 10 6 30. The substrate of clause 28 or 29, having an electrochemical impedance of greater than Ω. Clause 31. The substrate of any one of clauses 28 to 30, which is a vehicle component selected from an airfoil, a fuselage, an auxiliary power unit, an aircraft nose, a fuel tank, a tail cone, a panel, a coated lap joint between two or more panels, a wing, a wing-fuselage assembly, an aircraft structural composite, a fuselage body joint, or a wing rib-to-skin joint. Clause 32. A substrate according to any one of clauses 28 to 31, consisting of a metal substrate made from aluminium, aluminium alloy, nickel, iron, iron alloy, steel, titanium, titanium alloy, copper, copper alloy, or mixtures thereof. Clause 33. The substrate according to any one of clauses 28 to 32, made of an aluminium alloy. Clause 34. A method comprising: introducing polyaniline in acid form into the hydroxide to form polyaniline hydroxide; introducing a dopant into the polyaniline hydroxide to form a doped polyaniline, wherein the dopant is selected from triazole, thiazole, quinoline, salicylic acid, benzoic acid, glycolic acid, phosphoric acid, or a combination thereof; A method comprising: Clause 35. The method of clause 34, wherein the hydroxide is 1M ammonium hydroxide. [Example]

[0060] The composition may be substantially free of chromates and other heavy metals. The base composition may include a commonly used epoxy resin, an amine or amide curing agent, and a pigment. The conjugated polymer polyaniline, together with the dopant, forms the active pigment in the coating.

[0061] To form the binder component of the primer, a medium viscosity unmodified epoxy resin based on bisphenol A (e.g., Huntsman Araldite GY 250 or GY 9090) was used with an aliphatic polyamine hardener (e.g., Aradur 2973) or a polyamidoamine adduct (e.g., Huntsman Aradur 450). Reactive diluents (RD) or solvents were used to vary the viscosity of the primer composition.

[0062] Pigments such as titanium dioxide, talc, mica, and silica were used to impart properties such as opacity, viscosity, film strength, and transparency. Aluminum stearate acts as a thickener or suspending agent. Polyaniline is an active corrosion-inhibiting pigment.

[0063] While formulating the coating compositions, the volume solids, or VS (percentage of solids in the liquid coating), and the pigment volume concentration, or PVC (percentage of pigment in solids) were fixed.

[0064] To achieve a VOC of less than 300 g / L for the paint, the VS is preferably greater than 80%. The PVC of the primer composition is preferably 20 to 30. The pigments mentioned above make up the PVC, and the PVC is fixed at 20 in this test.

[0065] The terms paint and primer are used interchangeably in this disclosure.

[0066] Surface preparation and coating: The surface of Al alloy AA 2024 was pretreated using a commercial conversion coating (SurTec 650) according to MIL-DTL-5541. A primer was applied onto the conversion-coated Al alloy and allowed to cure in air for 10 days before testing. Coatings were prepared with and without the conjugated polymer polyaniline-dopant (adduct) and were designated as follows: 1) PANI-Polyaniline 2) PANI(D) - Dedoped polyaniline 3) PANI(P) - Polyaniline phosphate 4) PANI(B) - Polyaniline Benzoate 5) PANI(S) - Polyaniline Salicylate 6) PANI(Q) - Polyaniline Quinoline 7) PANI(BTA)-Polyaniline Benzotriazole 8) PANI(MBT) - Polyaniline Mercaptobenzothiazole 9) Blank - does not contain PANI

[0067] Synthesis of polyaniline-dopant (adduct) 1M (91.2 mL) distilled aniline was dissolved in 500 mL of 1M phosphoric acid (57.6 mL). A pre-chilled 1M solution of ammonium persulfate (APS) (45.6 gm / 120 mL deionized water) was added dropwise to the pre-chilled aniline-acid mixture over approximately 1.5 hours with constant stirring. The reaction was carried out at 5±2°C. After the addition, stirring was continued for 2 hours to ensure complete polymerization. Dark green polyaniline was obtained, confirming the formation of phosphate-doped PANI(P). The PANI(P) thus formed was filtered and washed repeatedly (3 times) with distilled water to remove excess acid. The PANI(P) was then dried in an oven at approximately 80°C for 2 hours. The dried PANI(P) was then pulverized using a mortar and pestle.

[0068] De-doping of PANI The synthesized PANI (P) was dedoped by mixing and stirring in 1 M ammonium hydroxide for 2 h. The dedoped polyaniline PANI (D) was filtered, washed repeatedly with deionized water (3 times), and dried.

[0069] Synthesis of PANI / adducts with various dopants Redoping of PANI (D) was performed by mixing PANI (D) in 1:1 benzoic acid (3 g / 1000 mL of deionized water), salicylic acid (2.48 g / 1000 mL of deionized water), benzotriazole (5 g / 1000 mL of deionized water), 8-hydroxyquinoline (6 g / 1000 mL of a 1:1 ethanol-water mixture), and 2-mercaptobenzothiazole (190 mg / 1000 mL of deionized water) and stirring for 4 hours. The redoped PANI was filtered, washed repeatedly with distilled water (3 times), and dried in an oven at 60 °C for 2 hours. Doped PANI or PANI adducts, PANI (B), PANI (S), PANI (BTA), PANI (Q), and PANI (MBT), were thus obtained.

[0070] Electrochemical evaluation of primer coatings To evaluate the self-healing and corrosion protection properties of the coatings, the following tests were performed. 1) Electrochemical Impedance Spectroscopy 2) Corrosion current mapping using the scanning vibrating electrode method (SVET) 3) Measurement of corrosion current from Tafel curves

[0071] Exemplary Compositions A typical composition for 100 mL of liquid primer is shown below. Note that PANI (5%) means that the polyaniline-dopant content is 5% of the PVC, not 5% of the total volume or mass of the paint. The same applies to TiO2, talc, etc.

[0072] [Table 1]

[0073] The VOC obtained with these compositions was 200-250 g / L. PANI-dopants, resins, and hardeners were changed during testing. The pigments (weighed according to calculations) were first premixed using a mortar and pestle. The resin was slowly added to this mixture with continuous mixing. The solvent and reactive diluent were slowly added with mixing. The entire mixture was thoroughly ground for 30 minutes. A drop of the paint prepared up to this point was taken from this and placed in a Hegman gauge to test the fineness of the grind. If the fineness was less than 7, grinding was continued for another 15 minutes and the fineness was tested. This process continued until the fineness of the paint dispersion was greater than 7 on the Hegman gauge. The paint was applied by spray / brush onto a trivalent chromium (Sur Tec 650) conversion coated AA 2024 alloy and allowed to cure for 10 days.

[0074] Electrochemical Impedance Spectroscopy-I Electrochemical impedance spectroscopy was used to continuously monitor the performance of coatings exposed to a specific corrosive environment (in this case, 3.5 wt% NaCl) by measuring the coating resistance. High coating resistance implies low permeability and good protection. Also, the presence of a single slope in the Bode plot indicates only a single time constant, corresponding to the coating resistance and capacitance. The presence of two slopes confirms the presence of two time constants, which implies the presence / initiation of a corrosion process on the metal surface.

[0075] A glass tube with a diameter of 1.2 cm and a length of approximately 3 cm was fixed on the coated aluminum alloy with adhesive, and the exposed area to the solution was 1.1 cm 2 A 3.5 wt% NaCl solution was poured into the glass tube. Platinum foil and a saturated calomel electrode were placed inside the glass tube. The paint was removed from one corner of the painted panel to make contact with the working electrode. This formed a three-electrode assembly.

[0076] The assembly was connected to an electrochemical impedance analyzer. Impedance measurements were performed in the frequency range of 100 kHz to 0.01 Hz with an AC amplitude of 20 mV for different immersion times. The coating resistance (R) was calculated from the impedance plot by fitting the experimental values ​​with a simple Randles equivalent circuit using Zsimpwin software (Princeton Applied Research). c ) and coating capacitance (C) values ​​were calculated.

[0077] The percentages of PANI-dopant mentioned in the examples below refer to % of PVC (pigment volume concentration). Example 1: 5% PANI-P with Araldite GY 250, Aradur 2973, and 5% reactive diluent. Reactive diluents are used to reduce viscosity and are typically mono-, di-, or tri-functional glycidyl ethers. Examples include Araldite DY-E, Araldite DY-D, and Araldite DY 025. The reactive diluent used in Example 1 was Araldite DY 3601, commercially available from Huntsman Advanced Materials of The Woodlands, Texas.

[0078] Bode plot of coating resistance: 10 (at low frequency) over 14 days 8 A high coating resistance, in the ohm range, is considered to be a coating with good corrosion resistance. Figure 1 is a Bode plot over time for Example 1 (5% PANI-P with Araldite GY 250, Aradur 2973, and 5% reactive diluent), according to one or more embodiments.

[0079] Example 2: 5% PANI-P with Araldite GY 9090, Aradur 2963, and 5% reactive diluent. The coating resistance was calculated as described above for the coating prepared from the composition of Example 2. The coating thickness was approximately 50 microns. 6A high coating resistance, on the order of more than an ohm, indicates good barrier properties that will provide good corrosion protection.

[0080] [Table 2]

[0081] Example 3: Araldite GY 250, Aradur 2973, 5% reactive diluent, and PANI-P The Bode plot of the coating without PANI shows a decrease in coating resistance compared to the plots of coatings containing 10, 15, and 20% PANI-P, demonstrating the effectiveness of the PANI-P corrosion inhibitor pigment (Figure 2).

[0082] Figure 2A is a Bode plot over time of Example 3 (Araldite GY 250, Aradur 2973, 5% reactive diluent) but without PANI-P, according to one or more embodiments. Figure 2B is a Bode plot over time of Example 3 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 10% PANI-P), according to one or more embodiments. Figure 2C is a Bode plot over time of Example 3 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 15% PANI-P), according to one or more embodiments. Figure 2D is a Bode plot over time of Example 3 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-P), according to one or more embodiments.

[0083] 10 over 60 days 7 A high coating resistance, on the order of more than an ohm, indicates good corrosion protection.

[0084] [Table 3]

[0085] Scanning Vibrating Electrode Technique (SVET) For SVET measurements, a mold was first made from polyvinyl chloride material using Araldite resin. A 1 cm square piece of Al alloy was then placed on the mold and fixed using Araldite resin. The test area was approximately 10 mm x 10 mm, and the rest of the surface was masked to avoid interference. The surface of the Al alloy in the mold was then prepared and coated in the same manner as the panel described above. An epoxy primer was applied by spraying onto the surface-treated AA 2024 alloy. After an 8-day curing period, artificial defects (small pinholes) were created in the coating, and the surface was observed for corrosion and self-healing ability using SVET.

[0086] All surfaces were assumed to be flat, so a four-point height scan method was used, adjusting a distance of 150 μm between the vibrating probe and the coated metal surface. The primary result of the SVET (surface potential data) was calibrated during function operation and used to generate the current density. Scans were performed at different time intervals.

[0087] The results showed that for coatings without PANI (i.e., blank), the occurrence of large current spikes (due to corrosion) in the defect area was accelerated, while coatings containing PANI (all dopants) suppressed the initial spike over time, as demonstrated by SVET mapping at various time intervals.

[0088] The mechanism of protection (or self-healing) is due to the formation of a passive film due to its redox activity: the emeraldine salt form of PANI present in the coating accepts electrons released by the metal oxidation reaction and is reduced to the emeraldine base form, forcing the metal surface to passivate. During this redox transition, dopants (phosphate, benzoate, salicylate, benzotriazole, mercaptobenzothiazole, and quinoline) in the polymer backbone are released, enhancing corrosion protection. This is evidenced by the fact that coatings containing "dedoped PANI" do not exhibit self-healing capabilities, but do not propagate corrosion like "blank" coatings.

[0089] SVET analysis of primer coatings containing PANI-benzoate Example 4: Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-B Figures 3A-3D show local current maps on the surface of coated aluminum recorded after exposure to 3.5% NaCl. The "initial" image was recorded after 5 minutes of exposure. The sudden anodic current flow in the defect area indicates the onset of accelerated corrosion. As exposure continues, corrosion activity in the defect area decreases, as evidenced by the decrease in the height of the current flow pattern in the 6- and 12-hour exposure images. After 24 hours of exposure, there is no anodic current flow (no peak). This indicates that the PANI dopant has self-healing activity in the epoxy coating on the aluminum surface, i.e., the coating defects have been repaired.

[0090] Figure 3A is an SVET plot of Example 4 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-B) at an "initial" time (5 minutes), according to one or more embodiments. Figure 3B is an SVET plot of Example 4 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-B) at 6 hours of NaCl exposure, according to one or more embodiments. Figure 3C is an SVET plot of Example 4 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-B) at 12 hours of NaCl exposure, according to one or more embodiments. Figure 3D is an SVET plot of Example 4 (Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI-B) at 24 hours of NaCl exposure, according to one or more embodiments.

[0091] SVET analysis of primer coatings containing no PANI (i.e., blanks) Figures 4A-4D show local current maps on the surface of coated aluminum recorded after exposure to 3.5% NaCl. The "initial" image was recorded after 5 minutes of exposure. The sudden anodic current flow in the defect area indicates the onset of accelerated corrosion. As exposure continued, corrosion activity in the defect area increased, as evidenced by the increased height and width of the current flow pattern in the 6- and 12-hour exposure images. After 24 hours of exposure, there was a large anodic current flow (many peaks), indicating that the PANI-free coating did not have the self-healing ability of the epoxy coating on the aluminum surface. Furthermore, the large number of peaks observed in the field of view also indicates that the film had poor barrier properties.

[0092] Figure 4A is an SVET plot of a PANI-free primer coating at an "initial" time (5 minutes), according to one or more embodiments. Figure 4B is an SVET plot of a PANI-free primer coating at 6 hours of NaCl exposure, according to one or more embodiments. Figure 4C is an SVET plot of a PANI-free primer coating at 12 hours of NaCl exposure, according to one or more embodiments. Figure 4D is an SVET plot of a PANI-free primer coating at 24 hours of NaCl exposure, according to one or more embodiments.

[0093] SVET analysis of primer coatings containing dedoped PANI Figures 5A-5D show local current maps on the surface of coated aluminum recorded after exposure to 3.5% NaCl. The "initial" image was recorded after 5 minutes of exposure. The sudden anodic current flow in the defect area indicates the onset of accelerated corrosion. As exposure continues, the corrosion activity in the defect area does not change significantly, as evidenced by the similar height and width of the current flow pattern in the 6- and 12-hour exposure images. After 24 hours of exposure, the corrosion activity remains nearly the same. This indicates that the coating containing "dedoped PANI" does not have the self-healing ability in the epoxy coating on the aluminum surface, but does not result in increased corrosion as in the coating without PANI (i.e., the blank).

[0094] Figure 5A is an SVET plot of a primer coating comprising dedoped PANI at an "initial" time (5 minutes), according to one or more embodiments. Figure 5B is an SVET plot of a primer coating comprising dedoped PANI at 6 hours of NaCl exposure, according to one or more embodiments. Figure 5C is an SVET plot of a primer coating comprising dedoped PANI at 12 hours of NaCl exposure, according to one or more embodiments. Figure 5D is an SVET plot of a primer coating comprising dedoped PANI at 24 hours of NaCl exposure, according to one or more embodiments.

[0095] Tafel polarization curves A Tafel plot serves as a diagram or illustration of the Tafel equation, which is primarily used to understand electrochemical kinetics, linking overpotential to electrochemical reaction rate.

[0096] Tafel plots are used to represent the results of the equations and identify information such as passivity, corrosion susceptibility, etc. This technique allows the corrosion current (I corr ) can be measured and used to calculate the corrosion rate. Such plots, along with equations, can be very useful in showing the life span of materials used in various industries.

[0097] The three-electrode assembly was connected to a potentiostat, and the open-circuit potential (OCP) of the painted panel was monitored for 20 minutes to allow for OCP stabilization. Once steady state was reached, potential sweeps on either side (+ve and -ve) of the OCP up to ±250 mV were performed separately in different regions at a scan rate of 0.5 mV / s on each side. Tafel polarization curves were obtained as a plot of the logarithm of current density (I) versus electrode potential (E) for a particular electrode-electrolyte combination by combining both the anodic and cathodic curves in a single plot. Experiments were performed at different locations on the coated surface (surface area exposed to the electrolyte = 1 cm²). The electrolyte used was a 3.5% NaCl solution.

[0098] Example 5: Araldite GY 250, Aradur 2973, 5% reactive diluent, and 20% PANI—(various dopants) Figure 6A is a Tafel polarization curve plot of a primer coating without PANI, according to one or more embodiments; Figure 6B is a Tafel polarization curve plot of a primer coating with PANI-P, according to one or more embodiments; Figure 6C is a Tafel polarization curve plot of a primer coating with PANI-Q, according to one or more embodiments; and Figure 6D is a Tafel polarization curve plot of a primer coating with PANI-S, according to one or more embodiments.

[0099] From the Tafel curves, the corrosion current (I corr ) values ​​were obtained.

[0100] [Table 4]

[0101] The blank coating (containing no PANI) exhibits the highest corrosion current, while the other coatings containing PANI-dopants exhibit corrosion currents 4 to 5 orders of magnitude lower. The coating containing dedoped PANI exhibits a slightly higher current than the coating containing doped PANI. This demonstrates the corrosion protection and self-healing effects of PANI and doped PANI in the coatings.

[0102] Electrochemical Impedance Spectroscopy-II Coated coupons were placed in contact with a 3.5% NaCl solution for approximately 60 days, and EIS measurements were taken intermittently on these surfaces. Other coated coupons were placed in a salt (5% NaCl) fog chamber for approximately 60 days, and EIS measurements were taken intermittently on these surfaces in a 3.5% NaCl solution.

[0103] A glass tube with a diameter of 1.2 cm and a length of approximately 3 cm was fixed on the coated aluminum alloy with adhesive, and the exposed area to the solution was 1.1 cm 2 A 3.5 wt% NaCl solution was poured into the glass tube. Platinum foil and a saturated calomel electrode were placed inside the glass tube. The paint was removed from one corner of the painted panel to make contact with the working electrode. This formed a three-electrode assembly.

[0104] The assembly was connected to an electrochemical impedance analyzer. Impedance measurements were performed in the frequency range of 100 kHz to 0.01 Hz with an AC amplitude of 20 mV for different immersion times. The coating resistance (R) was calculated from the impedance plot by fitting the experimental values ​​with a simple Randles equivalent circuit using Zsimpwin software. c ) values ​​were calculated.

[0105] These coatings contained 20% PANI-dopant and were compared to the reference standard pigment Sr chromate, blank, and dedoped PANI. The coatings containing PANI-dopant exhibited better coating resistance.

[0106] [Table 5]

[0107] The examples mentioned here relate to the more susceptible Al alloy 2024. The coating should also work well on other types of Al alloys.

[0108] Those familiar with the art of formulating paints and primers will understand that various variations in the components will result in coatings with different compositions and properties. The examples refer to specific resin systems from well-known manufacturers, but the use of similar resins from others is possible within the scope of this disclosure. While polyaniline is used extensively as an example in this disclosure, the use of other conjugated polymers, such as polypyrrole, polythiophene, etc., is also possible within the scope of this disclosure.

[0109] Overall, the present disclosure provides compositions, articles thereof, and methods for providing corrosion protection to substrates that respond to corrosive environments and provide corrosion protection to the substrate on an "on-demand" basis. Furthermore, the "on-demand" release of dopant from polyaniline reduces the reactivity between the dopant present in the composition and the epoxy.

[0110] As used herein, a "vehicle part" includes any part of a vehicle, e.g., a structural part, e.g., a panel or joint of an aircraft, automobile, etc. Vehicle parts include noses, fuel tanks, tail cones, panels, fuselages, coated lap joints between two or more panels, wing-fuselage assemblies, aircraft structural composites, fuselage body joints, wing rib-to-skin joints, and / or other interior parts. Vehicle parts also include any suitable part of an automobile, marine vehicle, wind turbine, housing / ground structure, drilling rig, etc.

[0111] The foregoing is directed to examples of the present disclosure, although other and further examples of the present disclosure may be devised without departing from the basic scope thereof. Further, while the foregoing is directed to methods applied to vehicle parts in the aerospace industry, for example, examples of the present disclosure may be directed to other non-aviation related applications, such as applications in the automotive industry, marine industry, energy industry, wind turbines, satellites, etc.

[0112] The description of various examples of the present disclosure is presented for illustrative purposes and is not intended to be exhaustive or to be limited to the disclosed examples. Numerous modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described examples. The terminology used herein has been selected to best explain the principles, practical applications, or technical improvements over those found in the marketplace of the examples, or to enable those skilled in the art to understand the examples disclosed herein. The foregoing is directed to examples of the present disclosure; however, other and further examples of the present disclosure may be devised without departing from its basic scope. Accordingly, no limitation of the present disclosure is intended. Similarly, whenever a composition, element, or group of elements is preceded by the transitional phrase "including," it is understood that the same composition or group of elements preceded by the transitional phrase "consisting essentially of," "consisting of," "selected from the group consisting of," or "is" is also contemplated, and vice versa.

Claims

1. 1. A composition comprising: Epoxy, Amino or amide hardeners, polyaniline, a dopant selected from triazolyl, thiazolyl, quinolinyl, glycolate, or a combination thereof, wherein the combination of the polyaniline and the dopant forms a first pigment; and a second pigment selected from titanium dioxide, silica, talc, mica, aluminum stearate, or a combination thereof; the first pigment comprises 6% by weight or less of the composition; the first pigment comprises a pigment volume concentration of the composition in an amount of 1% to 25%; having a volume solids content of 70% or more, based on the total volume of the composition; The polyaniline is optionally an emeraldine form of polyaniline. composition.

2. 10. The composition of claim 1, having a volatile organic content of 300 g / L or less.

3. The composition of claim 1 having a volumetric solids content of 80% or more, based on the total volume of the composition.

4. 10. The composition of claim 1, comprising (epoxy + amino and / or amide hardener) in an amount of 45 wt% to 85 wt%, based on the total weight of the composition.

5. 10. The composition of claim 1, comprising one or more epoxies in an amount of 40% to 55% by weight, based on the total weight of the composition; and / or an amino or amide hardener in an amount of 15% to 21% by weight, based on the total weight of the composition; and / or a polyaniline plus dopant in an amount of 0.1% to 6% by weight, based on the total weight of the composition, or alternatively a polyaniline plus dopant in an amount of 1% to 25% based on the pigment volume concentration of the composition.

6. 2. The composition of claim 1, wherein the epoxy is a bisphenol A type epoxy or a bisphenol F type epoxy.

7. 2. The composition of claim 1, wherein the molar ratio of the dopant to the aniline units of the polyaniline is from 0.3:1 to 1:

1.

8. 2. The composition of claim 1, wherein the dopant is a triazolyl selected from benzotriazole, triazolecarboxylic acid, or benzotriazolesulfonic acid, and / or the dopant is a thiazolyl selected from one or more of benzothiazole, thiazolecarboxylic acid, or mercaptobenzothiazole, and / or the dopant is a quinolinyl selected from 8-hydroxyquinoline or mercaptoquinoline, and / or the dopant is a glycolate selected from glycolate or thioglycolate.

9. the second pigment in an amount of 10% to 50% by weight, based on the total weight of the composition; or The composition of claim 1, comprising the second pigment in an amount of 20% to 40% based on the total volume of the composition.

10. 10. The composition of claim 1, comprising said titanium dioxide, said silica, said talc, said mica, and said aluminum stearate.

11. 10. The composition of claim 1, comprising titanium dioxide in an amount of 10% to 25%, based on the pigment volume concentration of the composition; and / or talc in an amount of 15% to 30%, based on the pigment volume concentration of the composition; and / or mica in an amount of 5% to 30%, based on the pigment volume concentration of the composition; and / or silica in an amount of 20% to 30%, based on the pigment volume concentration of the composition; and / or aluminum stearate in an amount of 1% to 3%, based on the pigment volume concentration of the composition.

12. The composition of claim 1, comprising titanium dioxide in an amount of 5% to 14% by weight, and / or talc in an amount of 6% to 12% by weight, and / or mica in an amount of 2% to 12% by weight, and / or silica in an amount of 8% to 13% by weight, and / or aluminum stearate in an amount of 0.1% to 0.6% by weight, based on the total weight of the composition.

13. 13. A substrate having a composition according to any one of claims 1 to 12 disposed thereon, wherein the cured composition thereon has a thickness of 5 μm to 100 μm, and / or the cured composition has a thickness of 10 μm to 100 μm when contacted with a 3.5% NaCl solution. 6 A substrate having an electrochemical impedance of greater than Ω.

14. 14. The substrate of claim 13, which is a vehicle component selected from an airfoil, a fuselage, an auxiliary power unit, an aircraft nose, a fuel tank, a tail cone, a panel, a coated lap joint between two or more panels, a wing, a wing-fuselage assembly, an aircraft structural composite, a fuselage body joint, or a wing rib-to-skin joint.

15. 14. The substrate according to claim 13, which consists of a metal substrate made from aluminum, an aluminum alloy, nickel, iron, an iron alloy, steel, titanium, a titanium alloy, copper, a copper alloy, or mixtures thereof, or optionally consists of an aluminum alloy.

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