Improved corrosion inhibitor coating compositions with thiirane crosslinkers and methods thereof

Abstract

To provide corrosion inhibitor coating compositions having facile reactions that proceed within acceptable process limitations, while affording acceptable or improved adhesion and corrosion inhibition.SOLUTION: A corrosion inhibitor coating composition includes a polymerized thiosemicarbazone and a thiirane crosslinker, where molecules of the thiirane crosslinker are difunctional. The corrosion inhibitor coating composition can include the thiirane crosslinker that may include an aliphatic thiirane, a tri-functional thiirane, a bisphenol thiirane, or a combination thereof. The corrosion inhibitor coating composition can be metal-free and catalyst-free. An article utilizing and a method of preparing the corrosion inhibitor coating composition are also disclosed. The method can include adding a thiourea to a difunctional epoxy terminated molecule in solution in the presence of a catalyst, converting the difunctional epoxy terminated molecule to a thiirane terminated difunctional molecule, and purifying the thiirane terminated difunctional molecule to produce a thiirane.SELECTED DRAWING: Figure 1B

Description

[Technical field]

[0001] Statement of Government Interest This invention was made with Government support under Contract No. W912HQ21C0067 awarded by the United States Army Corps of Engineers (USACE). The Government has certain rights in this invention.

[0002] The present teachings relate generally to corrosion inhibitor coating compositions, and more specifically to corrosion inhibitor coating compositions that include a thiirane crosslinker. [Background technology]

[0003] The use of chromium-containing corrosion inhibitors has been prevalent for decades due to their performance and durability in preventing corrosion on steel, aluminum, and other alloys used in aerospace manufacturing. In recent years, global regulations have restricted the use of chromium-containing corrosion inhibitors. New organic corrosion inhibitor molecules have been developed to replace the use of chromium in some applications. These organic corrosion inhibitor molecules require reaction with multifunctional resins to create durable coatings containing these inhibitors. Due to their chemical structure, organic corrosion inhibitor molecules do not react easily with the epoxy resins typically used in these types of coatings.

[0004] In embodiments, existing epoxy-based systems do not react sufficiently with these organic corrosion inhibitor molecules, and the reactions required for crosslinking do not proceed within the confines of possible application methods, thus requiring high temperatures and long reaction times to achieve complete reaction to provide sufficient coating properties and adhesion. Summary of the Invention [Problem to be solved by the invention]

[0005] Thus, there is a need to provide corrosion inhibitor coating compositions that provide acceptable or improved adhesion and corrosion protection while being reactive and within acceptable process limits.

[0006] The following presents a simplified summary in order to provide a basic understanding of some aspects of one or more embodiments of the present teachings. This summary is not an extensive overview and is not intended to identify key or critical elements of the present teachings or to delineate the scope of the disclosure. Rather, its primary purpose is merely to present one or more concepts in a simplified form as a prelude to the more detailed description that is presented later. [Means for solving the problem]

[0007] A corrosion inhibitor coating composition is disclosed that comprises a polymerized thiosemicarbazone and a thiirane crosslinker, where the thiirane crosslinker is a difunctional molecule. In embodiments of the corrosion inhibitor coating composition, the thiirane crosslinker can comprise an aliphatic thiirane, a trifunctional thiirane, a bisphenol thiirane, or a combination thereof. The corrosion inhibitor coating composition can be metal-free. The corrosion inhibitor coating composition can be catalyst-free. The thiirane crosslinker is present in an amount of about 0.1% to about 5.0% of the total weight of the corrosion inhibitor coating composition.

[0008] An article is disclosed that comprises a substrate and a corrosion inhibitor coating composition disposed on a surface of the substrate, the corrosion inhibitor coating composition comprising a polymerized thiosemicarbazone and a thiirane crosslinker, where the thiirane crosslinker can comprise an aliphatic thiirane, a trifunctional thiirane, a bisphenol thiirane, or a combination thereof. In an embodiment of the article, the corrosion inhibitor coating composition can be metal-free. The corrosion inhibitor coating composition can be catalyst-free. The corrosion inhibitor coating composition can have a thickness of about 100 nm to about 10 microns. The substrate can comprise a metal, a polymer, a polymer composite, or a combination thereof. The substrate can comprise nickel-plated steel. The substrate can comprise a transition metal. In the article, there is no adhesive or primer between the substrate and the corrosion inhibitor coating composition. The article can be a component or part of an aerospace or marine vehicle. The component or part of an aerospace or marine vehicle can be an exterior surface of an aerospace or marine vehicle.

[0009] A method of preparing a corrosion inhibitor coating composition is disclosed that may include forming a solution including polymerized thiosemicarbazone and a solvent, adding a thiirane crosslinker, which may include a thiirane-terminated difunctional molecule, to the solution, and mixing the thiirane crosslinker and the solution. An embodiment of the method of preparing a corrosion inhibitor coating composition may include adding thiourea to difunctional epoxy-terminated molecules in a solution in the presence of a catalyst, converting the difunctional epoxy-terminated molecules to thiirane-terminated difunctional molecules, and purifying the thiirane-terminated difunctional molecules before adding the thiirane-terminated difunctional molecules to the solution.

[0010] The described features, functions, and advantages can be achieved independently in various embodiments or can be combined in yet further embodiments, further details of which can be understood by reference to the following description.

[0011] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present teachings and, together with the description, serve to explain the principles of the disclosure. [Brief description of the drawings]

[0012] [Figure 1A] 1 is a schematic diagram of a vehicle according to the present disclosure. [Figure 1B] FIG. 1 illustrates the application of a structural element including a corrosion inhibitor coating composition applied to an aerospace vehicle according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] It should be noted that some details in these figures have been simplified and are drawn for ease of understanding of the present teachings, rather than to maintain strict structural accuracy, detail, and scale.

[0014] Reference will now be made in detail to exemplary embodiments of the present teachings, examples of which are illustrated in the accompanying drawings, and wherever possible, the same reference numbers will be used throughout the drawings to refer to the same, similar or like parts.

[0015] The present disclosure provides a corrosion inhibitor coating composition incorporating an epoxy resin with sulfur analogs in place of the epoxy ring. These sulfur analogs are known as thiiranes or episulfides. The reactivity of the corrosion inhibitor coating composition is improved, allowing the coating to be cured more quickly and at lower temperatures. This reduces processing time and unit cost per part. The corrosion inhibitor currently contains a thioamide, a component that reacts with the epoxy. Thioamides are poor nucleophiles for epoxy ring opening. The thiiranes are more reactive than the corresponding epoxies. With the addition of the thiiranes, the system cures more quickly. Another advantage is that the ring-opening reaction step produces secondary thiol groups (similar to epoxy ring opening producing secondary hydroxyl groups) that can improve adhesion to metal surfaces or other substrates.

[0016] The coating compositions of the present disclosure avoid the need for high temperatures and long heating times to initiate the reaction of the inhibitor system with the crosslinking resin to proceed to full cure. These compositions also avoid the need to add catalysts that may interfere with adhesion because the catalysts are small molecules that remain in the coating after cure and may migrate or leach out during the life of the coating.

[0017] In some examples, a corrosion inhibitor coating composition or formulation can be applied to protect the substrate and other layers or portions of the vehicle 100 from the environment. FIG. 1A shows a schematic diagram of a vehicle 100 according to one embodiment. As shown, the vehicle 100 can include an airplane. The vehicle 100 can also or alternatively include other types of aircraft, such as a helicopter, an unmanned aerial vehicle (UAV), a spacecraft, a marine vessel, etc. In other embodiments, the vehicle 100 can be or include a car, a boat, a train, etc. In still other embodiments, the systems and methods described below may not be implemented in a vehicle, but rather in a building. The vehicle 100 can include one or more toilets (one shown: 110). The toilet 110 can include a sink 112, a toilet bowl 114, and a sensor 116. The sensor 116 can sense / determine whether the toilet 110 is occupied (e.g., by a passenger) or unoccupied. For example, the sensor 116 can be or include a motion sensor. Vehicle 100 may also include one or more kitchens or galleys (one shown: 120). Kitchen 120 may include a sink 122, a dishwasher 124, and an ice maker 126. A corrosion inhibitor coating composition 128 may be applied onto one or more exterior surfaces or components of vehicle 100 to prevent or resist corrosion when exposed to various harsh environmental conditions.

[0018] FIG. 1B is a diagram depicting the application of a structural element including a corrosion inhibitor coating composition applied to an aerospace vehicle according to the present disclosure. The application of the coating composition or method of the present disclosure to an aerospace vehicle 100 is shown, whereby a substrate 130 of the vehicle is applied with a coating composition of the present disclosure. An exploded view 1C is shown in which a substrate surface layer 132 and a corrosion inhibitor coating composition layer 134 are provided on a surface of the substrate 130 of the vehicle to provide corrosion resistance or protection to the surface of the substrate 130 and / or to structural elements or portions of the vehicle. In one example, the application of the coating composition of the present disclosure is directed to an exterior surface of the aerospace vehicle 100. By way of example, an additional coating layer, such as a paint, coating, or other protective coating, can be applied to the corrosion inhibitor coating composition layer 134.

[0019] The corrosion inhibitor coating composition of the present disclosure includes a polymerized thiosemicarbazone and a thiirane crosslinker, where the thiirane crosslinker is a bifunctional molecule. By way of example, the polymerized thiosemicarbazone may have the following structure: [ka] The thiosemicarbazones include those having the formula:

[0020] The corrosion inhibitor coating composition has the following structure: [ka] The compound may include a thiirane crosslinker comprising a thiirane having the formula:

[0021] In other examples, the thiirane crosslinker may include an aliphatic thiirane, a trifunctional thiirane, a bisphenol thiirane, or a combination thereof. By way of example, the corrosion inhibitor coating composition is metal-free and substantially free of the presence of metals or metal-based compounds, resulting in a metal-free, completely organic passivation or corrosion inhibitor coating composition. By way of example, the corrosion inhibitor composition does not include a catalyst, since the thiirane crosslinker reacts under ideal or ambient conditions without the use of a catalyst. However, in some examples, a catalyst may be used in some environmental conditions or when it is desirable to further accelerate the crosslinking reaction during application or use of the corrosion inhibitor coating composition. By way of example, the thiirane crosslinker is present in an amount of about 0.1% to about 5.0% of the total weight of the corrosion inhibitor coating composition.

[0022] Such an article or component may include a substrate and a corrosion inhibitor coating composition disposed on a surface of the substrate, the corrosion inhibitor coating composition comprising a polymerized thiosemicarbazone and a thiirane crosslinker, the thiirane crosslinker comprising an aliphatic thiirane, a trifunctional thiirane, a bisphenol thiirane, or a combination thereof. The composition of the corrosion inhibitor coating composition may include components similar to those described herein. In certain examples, the article includes a corrosion inhibitor coating composition having a thickness of about 50 nm to about 1 micron, or about 50 nm to about 500 nm, or about 100 nm to about 10 microns. By way of example, the article includes a substrate comprising a metal, a polymer, a polymer composite, or a combination thereof. In certain examples, the substrate comprises nickel-plated steel or plating comprising one or more transition metals, including but not limited to scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, or combinations thereof. In other examples, the article does not comprise an adhesive or primer between the substrate and the corrosion inhibitor coating composition. The article may be or comprise a component or part of an aerospace or marine vehicle, or the article may be or comprise an exterior surface of an aerospace or marine vehicle.

[0023] The method for preparing the corrosion inhibitor coating composition includes forming a solution containing polymerized thiosemicarbazone and a solvent, adding a thiirane crosslinker containing a thiirane-terminated difunctional molecule to the solution, and mixing the thiirane crosslinker and the solution. The method for preparing the corrosion inhibitor coating composition may further include the intermediate steps of adding thiourea to the difunctional epoxy-terminated molecule in the solution in the presence of a catalyst to prepare the thiirane by converting the difunctional epoxy-terminated molecule to a thiirane-terminated difunctional molecule, and purifying the thiirane-terminated difunctional molecule before adding the thiirane-terminated difunctional molecule to the solution. Purification can be achieved by drying, filtering, evaporating, rinsing, or any separation procedure known to those skilled in the art.

[0024] Bifunctional thiirane molecules are chemical compounds that contain two functional groups identified as thiirane groups. Thiiranes are three-membered rings consisting of one sulfur atom and two R groups. The two R groups, R and R', represent different substituents or groups attached to the thiirane ring. Bifunctional thiirane molecules can have a variety of chemical properties and applications based on the specific substituents and reactions they may undergo. Thiiranes are highly reactive substances and exhibit unique properties that are different from alkyl sulfides and aryl sulfides that lack a three-membered ring. The properties of thiiranes are also different from those of oxiranes, or three-membered rings that contain an oxygen atom.

[0025] Examples of difunctional thiirane molecules include those based on di-, tri-, or tetrafunctional thiirane, as well as those based on acetophenone, phenolic resins, and aniline resins. All kinds of polyepoxides can be converted at any level from those with epoxy groups to those with thiirane groups. The epoxy type includes those based on triols, such as glycerol and trishydroxyethyl triisocyanurate. A common tetraol is pentaerythritol. Other polyols include sugars (all kinds), i.e., simple sugars (glucose, fructose, etc.), disaccharides (e.g., sucrose), or polysaccharides. Dextrins can also be utilized. Polyols derived from the condensation of phenols and ketones such as acetone result in bisphenol A. Others in this family include bisphenol F (derived from formaldehyde), bisphenol C (derived from cyclohexanone), 6F-bisphenol (derived from hexafluoroacetone), etc. The phenolic portion of the molecule can also be replaced with 2,6-dimethylphenol, or simply 2-methylphenol (also known as cresol), etc. The Ciba-Geigy MY 720 family of epoxies, starting from MDA (methylene-dianiline) where the two NH2 groups react with an excess of epichlorohydrin to give a mixture of triepoxy and tetraepoxy derivatives, can also be used for conversion to thiiranes. Possible uses and applications of bifunctional thiiranes molecules can include chemical synthesis, curing agents, chemical sensing applications, or pharmaceuticals, in addition to their use as crosslinkers or in forming crosslinks between polymer chains, as described herein.

[0026] Polymerized thiosemicarbazone molecules can be or include polymers or macromolecules containing repeat units derived from thiosemicarbazone monomers. Thiosemicarbazones are chemical compounds characterized by the presence of a thiosemicarbazide (-C(NH2)(NHR)-S-) functional group. Polymerization of thiosemicarbazone monomers involves linking these units together to form long chains or networks, resulting in polymeric materials. Applications of polymerized thiosemicarbazone molecules can be or include metal ion chelation, sensors, catalysis, drug delivery, antimicrobial materials, etc.

[0027] The present teachings provide an approach for adding epoxies and catalysts to current corrosion inhibitor formulations based on thiosemicarbazones, including the use of a separate resin-based system, such as a sulfur analog of the same epoxy system, that can react with the thioamides of the corrosion inhibitor formulation faster than the original epoxy composition. This improvement allows for less undesired reactions, lower cure temperatures, and less need for catalysts. Typical catalysts that can be avoided when using the present teachings may include organotin compounds or small organics such as 2-ethyl-4-methylimidazole and other tertiary amines that can subsequently volatilize and cause coating defects. These common amine catalysts also promote yellowing in some coatings. The corrosion inhibitor compositions described herein solve this problem.

[0028] The use of a thiirane instead of an epoxy, as exemplified in the following formula, is a key difference in the present teachings: The three-membered sulfur-containing ring has a lower energy barrier for ring opening compared to similar molecules with oxirane or epoxy rings. [ka]

[0029] Other methods for improving the reaction of epoxies with some reactive species require higher temperatures, longer reaction times, and the use of catalysts. These listed concepts have the drawback of higher production costs, lower production rates, and higher material costs. The compositions described herein can also be used in formulations to coat metal parts. The compositions can be applied by spraying, dipping, roller, or other methods known to those skilled in the art. The coated parts can then be dried in a heated oven as a batch process or in a heated tunnel in a continuous process to cure the parts and remove the solvent. Depending on the coating equipment used, the components can be mixed as needed. The corrosion inhibitor coating compositions of the present disclosure can be used or applied to a wide range of similar metal surfaces in addition to aluminum or steel for aerospace. Other transportation vehicles, containers, and components, from small parts to rail cars or cargo ships, can benefit from such coating compositions. The application of corrosion inhibitors can cost millions of dollars in both materials and labor, as well as disposal of the worn or used coating after stripping. By creating a more durable and effective coating, maintenance cycles are reduced in frequency, resulting in less labor, less material going to landfills, and less impact on the global environment. In some instances, remote sensing methods using NIR (near infrared) frequency devices can be utilized to enable non-destructive sensing of coating attributes such as thickness or coverage uniformity up to 10-20 meters away from the test surface.

[0030] The coating compositions containing oligomeric Schiff base corrosion inhibitors (thioamides) described herein utilize an alternative approach to the use or encapsulation of epoxies and catalysts, including the use of a separate resin system, such as a sulfur analog of the same epoxy system, that can react with the thioamide more quickly than the original epoxy. This is believed to allow for less unwanted reactions, lower cure temperatures, and less need for catalysts, without wishing to be bound by any particular theory. The thio ring opens more quickly, and ring opening can result in the formation of a polymer. After ring opening, the sulfur group can bond and react better with metals and can exhibit better adhesion when used in coating compositions. As discussed above, the system is believed to react more quickly and completely than epoxies, but with similar physical properties and performance. Such coating compositions can be used on landing gear and other aerospace metals, specifically Zn-Ni surfaces, as well as others described herein.

[0031] Further methods of forming or producing such oligomeric Schiff base corrosion inhibitors, also referred to as thioamides, thiosemicarbazones, or polymerized thiosemicarbazones, can be found in U.S. Pat. Nos. 11,725,080 and 11,713,374, the disclosures of which are incorporated herein by reference in their entirety. The present disclosure provides similar oligomeric compositions using thiirane resins or thiirane crosslinkers to form continuous coatings, where the reactive species are combined with multifunctional resins such as epoxies to form films that adhere well to metal surfaces resulting in durable corrosion inhibitor coating compositions. In some instances where a thiirane crosslinker is not used, the thiosemicarbazones react sluggishly and require high temperatures of up to 190° C. to cure. Previously known crosslinkers include difunctional epoxy molecules such as diglycidyl bisphenol A, often referred to as DGEBA. A typical structure is shown below: [ka] As shown in.

[0032] Reactive end groups on the corrosion inhibitor composition of the present disclosure include, but are not limited to, thioamides. These thioamides are less reactive, for example, in nucleophilic attack on epoxy groups. Some approaches previously considered may employ the addition of catalysts, often at levels up to 5% by weight of the coating composition solids. The catalysts used may be or may include small mobile molecules that remain in the coating, which may later migrate or leach out of the coating over time and use. This catalyst migration may cause defects in the coating, thereby compromising the integrity of the coating. Although examples of the present coating composition do not include a catalyst, some level of catalyst may be used instead in some examples. In other examples, adhesives may be used in combination with the coating of the present disclosure or as a pre-process step to apply the coating composition of the present disclosure. In still other examples, the coating composition may be applied without or without the use of a primer.

[0033] An alternative approach is to use another resin system that can react with thioamides more quickly than epoxy-functional materials. The present disclosure provides sulfur analogs of epoxy systems, such as those shown in the schematic diagram shown below. [ka]

[0034] The energy barrier for ring opening of thiiranes is lower than that of any corresponding epoxy. This difference can be exploited to provide coatings that cure at lower temperatures resulting in less tacky coating formulations with little or no catalyst, resulting in improved adhesion. Additionally, the present disclosure provides a method to convert epoxy-functional molecules to produce the corresponding thiiranes using sulfur donors such as thiourea or potassium thiocyanate. The reagents can be thiourea or potassium thiocyanate, which are readily available and inexpensive. The reaction conditions are system dependent, but can be accomplished by stirring at room temperature, e.g., 25°C, under reflux for several hours. The solvent used can be acetonitrile, or a mixture of water and ethanol, as illustrative examples. These are all common laboratory reagents and require only routine levels of safety procedures when used in a laboratory or industrial environment.

[0035] As an example, the synthesis of thiiranes from epoxides has been demonstrated using thiourea as a reagent in the presence or absence of ethanol as a solvent. In the absence of ethanol, only certain aromatic or heteroaromatic epoxides react with thiourea to give thiiranes in lower yields compared to procedures involving the use of potassium thiocyanate (KSCN). Reactions using KSCN are exothermic and may result in the formation of alkenes in some cases. The presence of weakly hydrated ethanol makes the reactivity of thiourea similar to that of KSCN, and alkenes are not formed from furan epoxides. These methods can efficiently convert aliphatic and cyclic epoxides to thiiranes in high yields. Different solvents can affect the outcome of the reaction differently, and stable epoxides provide improved results. In some cases, the presence of ethanol can stabilize certain epoxides to prevent desulfurization and facilitate thiiranes formation.

[0036] Corrosion prevention substrate The substrate that may be protected from corrosion by a corrosion inhibitor coating composition comprising a Schiff base oligomer or composition thereof may be any suitable substrate, such as a metal substrate or a plastic substrate. A metal substrate may include any substrate material having at least a portion of its surface that is metallic, e.g., a portion of its outer surface is metallic. A metal substrate may include any metal that requires protection from corrosion. A metal substrate may include a metal or alloy selected from aluminum, e.g., an aluminum alloy. A metal substrate may be an aluminum alloy, e.g., an alloy of aluminum with one or more metals selected from the group consisting of copper, magnesium, manganese, silicon, tin, zinc, and combinations thereof. An aluminum alloy may be an alloy that includes copper. A metal substrate may be a copper-containing alloy, such as a copper-containing aluminum alloy. The amount of copper in the alloy may be about 1% to about 20% by weight, about 1% to about 18% by weight, about 1% to about 10% by weight, or about 1% to about 6% by weight. An aluminum alloy may be an aerospace alloy, e.g., AA2XXX and AA7XXX types. For example, the aluminum alloy may be of the AA2024 and AA7075 types. The aluminum alloy may be an automotive alloy, such as an AA6XXX type. The aluminum alloy may be a marine alloy, such as an AA5XXX type. By way of example, surface metals, such as those found in coatings or platings, may be composed of one or more of the foregoing compositions.

[0037] Other exemplary substrates may include metals such as nickel-plated steel, other nickel-plated metals, cadmium-plated metals, or zinc-plated metals, or any combination of the substrate materials described. Other transition metal-plated metals or other surfaces may be suitable substrates as well. Other suitable substrates may include titanium, aluminum, epoxy, or composite panel materials including metals that are subject to corrosion or require a passivation coating in the absence of a coating composition as described herein.

[0038] composition The composition of the present disclosure may further include a solvent to provide solubility / dispersibility of the Schiff base oligomer. The solvent may be water, a glycol, or a ketone. The glycol may include a glycol acetate, such as a glycol ether acetate. The ketone may include acetone or pentanone. In some embodiments, the solvent may include 1-methoxy-2-propanol acetate, 4-methyl-2-pentanone, acetone, butoxyethanol, dimethyl carbamate, or a combination thereof.

[0039] The concentration of the Schiff base oligomer may be from about 0.001% to about 20% by weight, such as from about 0.1% to about 10% by weight, for example from about 1% to about 5% by weight, alternatively from about 5% to about 10% by weight, based on the total weight of all solids, which can provide solubility / dispersibility of the Schiff base oligomer.

[0040] In some embodiments, the molar ratio of metal (e.g., metal salt:Schiff base oligomer) in the composition is provided with an excess of metal (e.g., metal salt) compared to the Schiff base oligomer due to the presence of multiple moieties of the Schiff base oligomer that can interact with the metal. For example, the molar ratio of metal salt:Schiff base oligomer in the composition can be greater than about 1:1, greater than about 1.1:1, greater than about 1.2:1, greater than about 1.3:1, greater than about 1.4:1, greater than about 1.5:1, greater than about 1.6:1, greater than about 1.7:1, greater than about 1.8:1, greater than about 1.9:1, greater than about 2:1, greater than about 3:1, greater than about 4:1, greater than about 5:1, greater than about 6:1, greater than about 7:1, greater than about 8:1, greater than about 9:1, or greater than about 10:1. The ratio of metal salt:Schiff base oligomer in the composition may be less than about 45:1, less than about 40:1, less than about 35:1, less than about 30:1, less than about 25:1, less than about 20:1, less than about 15:1, or less than about 10:1. The ratio of metal:corrosion inhibitor in the composition may be greater than about 1:1 to about 45:1, about 1.5:1 to about 40:1, about 2:1 to about 35:1, about 2.5:1 to about 30:1, about 3:1 to about 25:1, about 3.5:1 to about 20:1, about 4:1 to about 15:1, or about 5:1 to about 10:1. For example, the ratio of metal:corrosion inhibitor in the composition may be from about 1.1:1 to about 45:1, from about 1.2:1 to about 40:1, from about 1.3:1 to about 35:1, from about 1.4:1 to about 30:1, from about 1.5:1 to about 25:1, from about 1.6:1 to about 20:1, from about 1.7:1 to about 15:1, from about 1.8:1 to about 10:1, from about 1.9:1 to about 9:1, or from about 2:1 to about 8:1. In the examples provided herein, the compositions of the present disclosure are metal-free or substantially metal-free.

[0041] The corrosion inhibitor composition is suitable for use and application to a variety of substrates, such as metal substrates, and may be provided, for example, as a coating composition. The composition may include one or more other additives or corrosion inhibitors suitable for use with the intended substrate.

[0042] After the composition is deposited on the substrate, the solvent (if used) can be partially, substantially, or completely removed by any suitable curing process. For example, the coating composition can be applied to the substrate either in a wet state or in a "not fully cured" state that dries or cures over time, i.e., the solvent evaporates. The coating can be dried or cured at ambient temperature or by accelerated means, such as an ultraviolet curing system, to form a film or "cured" paint. The coating can also be applied in a semi-cured or fully cured state, such as an adhesive.

[0043] The composition may be a coating composition comprising a film-forming organic polymer. The coating composition may be a paint composition. The coating composition may comprise one or more resins, such as epoxy-based resins. The coating composition may be a paint composition, such as an epoxy resin-based paint composition.

[0044] The coating composition may be a powder coating composition, such as a powder coating composition suitable for use in powder coating a variety of metal substrates, including aluminum alloys or steels, as described herein.

[0045] The compositions of the present disclosure may include one or more additives, such as pigments, fillers, and extenders. Examples of suitable additives that may be combined with the corrosion inhibitors described herein include, for example, binders, solvents, pigments (including soluble or insoluble extenders, fillers, corrosion inhibitor pigments, etc.), additives (e.g., curing agents, surfactants, dyes, amino acids, etc.), etc. It should be noted that some additives may also be properly considered pigments and vice versa (e.g., matting agents). More specifically, these "additives" include, but are not limited to, glycine, arginine, methionine, and derivatives of amino acids such as methionine sulfoxide, methyl sulfoxide, and iodides / iodates, gelatin and gelatin derivatives such as animal and fish gelatin derivatives, linear and cyclic dextrins such as alpha and beta cyclodextrin, triflic acid, triflates, acetates, talc, kaolin, organic ion exchange resins such as organic cation and anion exchange resins, organic ion exchange resins pre-exchanged or reacted with salts, oxides, and / or mixed oxides of rare earth materials, and / or metal sulfates such as sulfates of rare earth materials, magnesium sulfate, calcium sulfate (anhydrous and hydrated forms), strontium sulfate, barium sulfate, and the like, and combinations thereof.

[0046] The composition may also include other additives such as rheology modifiers, fillers, reinforcing agents, heat or UV stabilizers, flame retardants, lubricants, surfactants, etc. The additives are typically present in an amount of less than about 10% by weight of the total composition after curing. Examples include: (a) rheology modifiers such as hydroxypropyl methylcellulose (e.g., Methocell 311, Dow), modified ureas (e.g., BYK 411, 410), and polyhydroxycarboxylic acid amides (e.g., Byk 405); (b) film-forming agents such as esters of dicarboxylic acids (e.g., Lusolvan FBH, BASF) and glycol ethers (e.g., Dowanol, Dow); (c) wetting agents such as fluorosurfactants (e.g., 3M Fluorad) and polyether-modified polydimethylsiloxanes (e.g., Byk 307, 333); (d) surfactants such as fatty acid derivatives (e.g., Bermadol SPS 2543, Akzo) and quaternary ammonium salts; (e) dispersants such as non-ionic surfactants based on primary alcohols (e.g., Merpol 4481, Dupont) and alkylphenol-formaldehyde-bisulfide condensates (e.g., Clariants 1494); (f) antifoaming agents, (g) corrosion inhibitors such as phosphate esters (e.g., ADD APT, Anticor C6), alkyl ammonium salts of (2-benzothiazolylthio)succinic acid (e.g., Irgacor 153 CIBA), and triazine dithiols; (h) stabilizers such as benzimidazole derivatives (e.g., Bayer, Preventol BCM, biocidal film protectors); (i) leveling agents such as fluorocarbon modified polymers (e.g., EFKA 3777); (j) Pigments or dyes such as fluorescent agents (Royale Pigments and chemicals); (k) organic and inorganic dyes, such as fluoresceins; (l) Lewis acids such as lithium chloride, zinc chloride, strontium chloride, calcium chloride, and aluminum chloride; (m) Suitable flame retardants to retard flame spread, heat release, and / or smoke generation, which may optionally include any of the following (or a combination thereof):

[0047] Phosphorus derivatives such as molecules containing phosphate, polyphosphate, phosphite, phosphazine, and phosphine functional groups, for example, melamine phosphate, dimelamine phosphate, melamine polyphosphate, ammonium phosphate, ammonium polyphosphate, pentaerythritol phosphate, melamine phosphite, and triphenylphosphine.

[0048] Nitrogen-containing derivatives such as melamine, melamine cyanurate, melamine phthalate, melamine phthalimide, melam cyanurate, melem cyanurate, melon cyanurate, hexamethylenetetraamine, imidazole, adenine, guanine, cytosine, and thymine.

[0049] Molecules containing boric acid functional groups such as ammonium borate and zinc borate.

[0050] Molecules containing two or more alcohol groups, such as pentaerythritol, polyethylene glycol, polyglycols, and carbohydrates, e.g., glucose, sucrose, and starch.

[0051] Molecules that endothermically release non-combustible decomposition gases, such as metal hydroxides, e.g., magnesium hydroxide and aluminum hydroxide.

[0052] Expandable graphite.

[0053] Working Example Reaction mechanism of epoxy to thiirane:

[0054] [Table 1] *Used for extraction

[0055] mechanism: [ka]

[0056] procedure: 1. EPON828, 5 mL of acetonitrile, and 0.152 g of thiourea are added in a 25 mL round bottom flask with stirring. In the exemplary scheme shown herein, n refers to the number of repeat units of the designated structure representing the EPON828 material, and is understood to be a non-limiting example of the conversion of an epoxide to a thiirane. In the non-limiting example described herein, the average repeat unit is understood to be n=0.2. 2. 0.110 g of cerium ammonium nitrate is then added with stirring and reflux. The progress of the reaction is monitored using TLC. 3. To extract, prepare a mixture of 10 mL of water and 10 mL of chloroform. Use a separatory funnel. 4. The product must be separated in the chloroform phase, and the chloroform must be removed by rotary evaporation to extract the product. A drying agent such as anhydrous magnesium sulfate can be added to the chloroform solution, followed by filtration, and then the chloroform can be removed. 5. Repeat the extraction process three times.

[0057] Reaction of thiiranes with Schiff bases:

[0058] [Table 2]

[0059] mechanism: [ka]

[0060] procedure: A 100 mL three-necked round-bottom flask with side neck fitted with a thermometer is charged with the thiirane polymer (3.7). A PTFE stir bar is added and the flask is placed on a magnetic stirrer. 5.0 mL of MIBK is added and stirring is started. In a 50 mL beaker, inhibitor (1.4 g, 0.005 mol) is added and dissolved in 4 mL of DMF. The inhibitor solution is added dropwise to the flask while stirring. Shortly after the inhibitor addition, the reaction mixture turns yellow. The beaker is rinsed with an additional 1.0 mL of DMF and added to the flask. A solution of catalyst DMP-30 (0.014 g, 0.000052 mol) in 2.0 mL of MIBK is added to the flask and stirring is continued for 3 h at room temperature.

[0061] The four active hydrogens from the two -NH2 groups of the inhibitor were considered to be involved in the thiirane ring-opening reaction.

[0062] Catalyst-inhibitor molar concentration 1%.

[0063] Although the present teachings have been illustrated with respect to one or more embodiments, changes and / or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. For example, while a process has been described as a series of acts or events, it will be understood that the present teachings are not limited by the ordering of such acts or events. Some acts may occur in different orders and / or simultaneously with other acts or events other than those described herein. Also, not all process steps are required to implement a methodology in accordance with one or more aspects or embodiments of the present teachings. It will be understood that structural objects and / or processing steps can be added, or existing structural objects and / or processing steps can be removed or modified. Furthermore, one or more of the acts depicted herein may be performed in one or more separate acts and / or steps. Furthermore, to the extent that the terms "including," "includes," "having," "has," "with," or variations thereof are used in any of the detailed description and claims, such terms are intended to be inclusive terms, similar to the term "comprising." The term "at least one of" is used to mean that one or more of the listed items may be selected. Additionally, in the description and claims herein, the term "on" as used with respect to two materials, one "on" the other, means at least some contact between the materials, while "over" means that the materials are in close proximity but may have one or more additional intervening materials that may, but need not, be in contact. As used herein, neither "on" nor "over" imply any directionality. The term "conformal" describes a coating material in which the angle of the underlying material is maintained by the conformal material.The term "about" indicates that the recited value may vary somewhat, but only to the extent that this variation does not result in incompatibility of the process or structure to the illustrated embodiment. The terms "couple," "coupled," "connect," "connection," "connected," "in connection with," and "connecting" refer to "in direct connection with" or "in connection with via one or more intermediate element or members." Finally, the term "exemplary" or "illustrative" indicates that the description is not ideal but is used as an example. Other embodiments of the present teachings may be apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the present teachings being indicated by the following claims. [Explanation of symbols]

[0064] 100 Vehicles 110 Toilet 112 Sink 114 Toilet 116 Sensors 120 Kitchen 122 Sink 124 Dishwasher 126 Ice maker 128 Corrosion inhibitor coating composition 130 Substrate 132 Substrate surface layer 134 Corrosion inhibitor coating composition layer

Claims

1. a polymeric thiosemicarbazone; Thiirane crosslinker and Including, the thiirane crosslinker is a bifunctional molecule; Corrosion inhibitor coating composition (128).

2. The polymerized thiosemicarbazone has the following structure: 【Chemistry 1】 2. The corrosion inhibitor coating composition of claim 1, comprising a thiosemicarbazone having the formula:

3. The thiirane crosslinker has the following structure: 【Chemistry 2】 10. The corrosion inhibitor coating composition (128) of claim 1 comprising a thiirane having the formula:

4. 10. The corrosion inhibitor coating composition of claim 1, wherein the thiirane crosslinker comprises an aliphatic thiirane, a trifunctional thiirane, a bisphenol thiirane, or a combination thereof.

5. 10. The corrosion inhibitor coating composition of claim 1, wherein the corrosion inhibitor coating composition is metal-free.

6. 10. The corrosion inhibitor coating composition of claim 1, wherein the corrosion inhibitor coating composition is catalyst-free.

7. 10. The corrosion inhibitor coating composition (128) of claim 1, wherein the thiirane crosslinker is present in an amount of about 0.1% to about 5.0% of the total weight of the corrosion inhibitor coating composition (128).

8. A substrate (130); a corrosion inhibitor coating composition (128) disposed on a surface of the substrate (130), comprising: Polymeric thiosemicarbazones, and Thiirane Crosslinker A corrosion inhibitor coating composition (128) comprising Including, the thiirane crosslinker comprises an aliphatic thiirane, a trifunctional thiirane, a bisphenol thiirane, or a combination thereof; Goods.

9. The polymerized thiosemicarbazone has the following structure: 【Chemistry 3】 9. The article of claim 8, comprising a thiosemicarbazone having the formula:

10. The article of claim 8, wherein the corrosion inhibitor coating composition (128) is metal free.

11. The article of claim 8, wherein the corrosion inhibitor coating composition (128) is catalyst-free.

12. The article of claim 8, wherein the corrosion inhibitor coating composition (128) has a thickness of from about 100 nm to about 10 microns.

13. The article of claim 8 , wherein the substrate (130) comprises a metal, a polymer, a polymer composite, or a combination thereof.

14. The article of claim 8 , wherein the substrate (130) comprises nickel-plated steel.

15. The article of claim 8 , wherein the substrate (130) comprises a transition metal.

16. The article of claim 8, wherein there is no adhesive or primer between the substrate (130) and the corrosion inhibitor coating composition (128).

17. The article of claim 8 , wherein the article is a component or part of an aerospace vehicle (100) or a marine vehicle (100).

18. The article of claim 17, wherein the component or part of the aerospace vehicle (100) or the marine vehicle (100) is an exterior surface of the aerospace vehicle or the marine vehicle.

19. forming a solution comprising polymerized thiosemicarbazone and a solvent; adding a thiirane crosslinker comprising a thiirane-terminated bifunctional molecule to the solution; mixing the thiirane crosslinker and the solution; 2. A method for preparing a corrosion inhibitor coating composition (128), comprising:

20. adding thiourea to difunctional epoxy-terminated molecules in solution in the presence of a catalyst; converting the difunctional epoxy-terminated molecule to a thiirane-terminated difunctional molecule; purifying the thiirane-terminated bifunctional molecule prior to adding the thiirane-terminated bifunctional molecule to the solution; 20. The method of preparing the corrosion inhibitor coating composition (128) of claim 19, further comprising:

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