Improved corrosion inhibiting coatings with epithio ethane crosslinkers and methods thereof

Abstract

The invention relates to an improved corrosion inhibiting coating with an epithio ethane crosslinker and a method thereof. Specifically, a corrosion inhibitor coating composition comprises a polymerized thiosemicarbazone and an epithio ethane crosslinker, where the epithio ethane crosslinker is a bifunctional molecule. The corrosion inhibitor coating composition may include the case that the episulfide ethane crosslinker may include aliphatic episulfide ethane, trifunctional episulfide ethane, bisphenol episulfide ethane, or a combination thereof. The corrosion inhibitor coating composition may be metal-free and catalyst-free. Also disclosed are articles utilizing the corrosion inhibitor coating composition and methods of making the corrosion inhibitor coating composition, which may include adding thiourea to a bifunctional epoxy-terminated molecule in a solution in the presence of a catalyst, converting the bifunctional epoxy-terminated molecule to an epithio ethane-terminated bifunctional molecule, removing the epithio ethane-terminated bifunctional molecule from the bifunctional molecule, and removing the epithio ethane-terminated bifunctional molecule from the epithio ethane-terminated bifunctional molecule. And purifying the ethane episulfide terminated bifunctional molecule to produce ethane episulfide.

Description

[0001] Statement of Government Interest

[0002] This invention was made with government support under Contract No. W912HQ21C0067 awarded by the U.S. Army Corps of Engineers (USACE). The government has certain rights in this invention. Technical Field

[0003] The present invention relates generally to corrosion inhibiting coatings and, more particularly, to corrosion inhibiting coatings containing ethylene sulfide crosslinks. Background Art

[0004] Chromium-containing corrosion inhibitors have been widely used for decades due to their performance and durability in preventing corrosion on steel, aluminum and other alloys used in aerospace manufacturing. Recently, the use of chromium-containing corrosion inhibitors has been restricted by global regulations. New organic corrosion inhibitor molecules have been developed to replace the use of chromium in some applications. These organic corrosion inhibitor molecules need to be reacted with multifunctional resins to produce durable coatings containing these inhibitors. Due to the chemical structure of organic corrosion inhibitor molecules, they do not readily react with epoxy resins that are typically used for coatings of this nature.

[0005] In embodiments, existing epoxy-based systems are not sufficiently reactive with these organic-based corrosion inhibitor system molecules and the reactions required for crosslinking cannot be performed within the constraints of possible application methods. Therefore, high temperatures and long reaction times are required to achieve complete reaction to provide adequate coating properties and adhesion.

[0006]

[0006] Therefore, there is a need to provide corrosion inhibiting compositions that react readily within acceptable processing limits while providing acceptable or improved adhesion and corrosion inhibition. Summary of the invention

[0007] A simplified overview is provided below to provide a basic understanding of some aspects of one or more embodiments of the present invention. This overview is not a broad overview, nor is it intended to confirm the key or key elements of the present invention, nor is it intended to explain the scope of the present invention. On the contrary, its main purpose is only to present one or more concepts in a simplified form as a prelude to the detailed description provided subsequently.

[0008] A corrosion inhibitor coating composition is disclosed, comprising a polymerized thiosemicarbazone and an ethylene sulfide crosslinker, wherein the ethylene sulfide crosslinker is a bifunctional molecule. In an embodiment of the corrosion inhibitor coating composition, the ethylene sulfide crosslinker may include an aliphatic ethylene sulfide, a trifunctional ethylene sulfide, a bisphenol ethylene sulfide, or a combination thereof. The corrosion inhibitor coating composition may not contain a metal. The corrosion inhibitor composition may not include a catalyst. The ethylene sulfide is present in an amount of about 0.1% to about 5.0% of the total weight of the corrosion inhibitor coating composition.

[0009] An article comprising a substrate is disclosed, the article comprising a corrosion inhibitor coating composition disposed on a surface of the substrate, the corrosion inhibitor coating composition may comprise a polymerized thiosemicarbazone and an ethylene sulfide crosslinker, and the ethylene sulfide crosslinker may comprise an aliphatic ethylene sulfide, a trifunctional ethylene sulfide, a bisphenol ethylene sulfide, or a combination thereof. Embodiments of the article may include the following: the corrosion inhibitor coating composition may not comprise a metal. The corrosion inhibitor composition may not comprise a catalyst. The corrosion inhibitor coating composition may have a thickness of about 100 nm to about 10 microns. The substrate may comprise a metal, a polymer, a polymer composite, or a combination thereof. The substrate may comprise nickel-plated steel. The substrate may comprise a transition metal. In the article, there is no adhesive or primer between the substrate and the corrosion inhibitor coating composition. The article may be a component of an aerospace vehicle or a watercraft. The component of an aerospace vehicle or a watercraft may be an outer surface thereof.

[0010] A method of preparing a corrosion inhibitor coating composition is disclosed, the method may include forming a solution including polymerized thiosemicarbazone and a solvent, adding an ethylene sulfide crosslinker that may include ethylene sulfide-terminated bifunctional molecules to the solution, and mixing the ethylene sulfide crosslinker with the solution. An embodiment of the method of preparing a corrosion inhibitor coating composition may include adding thiourea to bifunctional epoxy-terminated molecules in the solution in the presence of a catalyst, converting the bifunctional epoxy-terminated molecules to ethylene sulfide-terminated bifunctional molecules, and purifying the ethylene sulfide-terminated bifunctional molecules before adding the ethylene sulfide-terminated bifunctional molecules to the solution.

[0011] The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen in the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. In the drawings:

[0013] Figure 1A A schematic diagram of a carrier of the present invention is shown.

[0014] Figure 1B Depicted is the use of a structural component comprising a corrosion inhibiting composition applied to an aerospace vehicle of the present invention.

[0015] It should be noted that some details of the drawings have been simplified and are drawn to facilitate understanding of the invention rather than maintaining strict structural accuracy, detail, and scale. DETAILED DESCRIPTION

[0016] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same, similar or similar parts.

[0017] The present invention provides a corrosion inhibiting composition comprising an epoxy resin having a sulfur analog that replaces the epoxy ring. These sulfur analogs are called thioethanes or episulfides. The reactivity of the corrosion inhibiting composition is improved, which allows the coating to cure faster at lower temperatures. This reduces processing time and reduces the unit cost of each component. Corrosion inhibitors currently include thioamides, which are components that react with epoxy groups. Thioamides are poor nucleophiles for epoxy ring opening. Thioethane analogs are more reactive than the corresponding epoxy groups. By adding thioethane analogs, the system cures faster. Another benefit is that the ring opening reaction step generates secondary thiol groups (similar to the epoxy ring opening reaction that produces secondary hydroxyls), which can enhance adhesion to metal surfaces or other substrates.

[0018] The coating compositions of the present invention avoid the need for high temperatures and extended heating times to initiate the reaction between the inhibitor system and the crosslinking resin to proceed to full cure. These compositions also avoid the need to add catalysts that may interfere with adhesion because catalysts are smaller molecules that remain in the coating after curing and may migrate or leach out during the life of the coating.

[0019] In some examples, a corrosion inhibitor coating composition or formulation may be applied to protect the substrate and other layers or portions of the vehicle 100 from environmental influences. Figure 1AA schematic diagram of a vehicle 100 according to an embodiment is shown. As shown, the vehicle 100 may include an aircraft. The vehicle 100 may also or alternatively include other types of aircraft, spacecraft, ships, etc., such as helicopters, unmanned aerial vehicles (UAVs), etc. In other embodiments, the vehicle 100 may be or include a car, a ship, a train, etc. In other embodiments, the systems and methods described below may not be implemented in a vehicle, but may be implemented in a building. The vehicle 100 may include more than one bathroom (one is shown: 110). The bathroom 110 may include a sink 112, a toilet 114, and a sensor 116. The sensor 116 may sense / determine whether the bathroom 110 is occupied (e.g., occupied by a passenger). For example, the sensor 116 may be or include a motion sensor. The vehicle 100 may also include more than one kitchen or onboard kitchen (one is shown: 120). The kitchen 120 may include a sink 122, a dishwasher 124, and an ice maker 126. A corrosion inhibitor coating composition 128 may be applied to one or more exterior surfaces or components of the vehicle 100 to prevent or resist corrosion when exposed to various harsh environmental conditions.

[0020] Figure 1B Depicted is the application of a structural component comprising a corrosion inhibiting composition of the present invention applied to an aerospace vehicle. The application of the coating composition or method of the present invention is shown on an aerospace vehicle 100, whereby a vehicle substrate 130 is coated with the coating composition of the present invention. Exploded view 1C shows a vehicle substrate surface 130 having a substrate surface layer 132 and a corrosion inhibitor coating composition layer 134 to impart corrosion resistance or corrosion inhibition to the surface of the substrate 130 and / or a structural component of the vehicle or a portion of the vehicle. In one example, the application of the coating composition of the present invention is directed to an exterior surface of an aerospace vehicle 100. In an example, an additional coating, such as a paint, coating, or other protective coating, may be applied over the corrosion inhibitor coating composition layer 134.

[0021] The corrosion inhibitor coating composition of the present invention includes polymerized thiosemicarbazone and ethylene sulfide crosslinker, wherein the ethylene sulfide crosslinker is a bifunctional molecule. In an example, the polymerized thiosemicarbazone includes a thiosemicarbazone having the following structure:

[0022]

[0023] The corrosion inhibitor coating composition may include the following: the ethylene sulfide crosslinking agent includes ethylene sulfide having the following structure:

[0024]

[0025] In other examples, the ethylene sulfide crosslinking agent may include aliphatic ethylene sulfides, trifunctional ethylene sulfides, bisphenol ethylene sulfides, or combinations thereof. In examples, the corrosion inhibitor coating composition does not contain metals, and is substantially free of metals or metal-based compounds, thereby producing a completely organic, metal-free passivating or corrosion inhibiting coating composition. In examples, the corrosion inhibitor composition does not contain a catalyst because the ethylene sulfide crosslinking agent 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 in cases where it is desired to have a more rapid crosslinking reaction during the application or use of the corrosion inhibitor coating composition. In examples, the ethylene sulfide crosslinking agent is present in an amount of about 0.1% to about 5.0% of the total weight of the corrosion inhibitor coating composition.

[0026] As previously described, the article or component may include a substrate, a corrosion inhibitor coating composition disposed on the surface of the substrate, the corrosion inhibitor coating composition comprising a polymerized thiosemicarbazone and an ethylene sulfide crosslinker, wherein the ethylene sulfide crosslinker comprises an aliphatic ethylene sulfide, a trifunctional ethylene sulfide, a bisphenol ethylene sulfide, or a combination thereof. The composition of the corrosion inhibitor coating composition may include ingredients similar to those described herein. In some instances, the thickness of the corrosion inhibitor coating composition included in the article is from about 50 nm to about 1 micron, or from about 50 nm to about 500 nm, or from about 100 nm to about 10 microns. In an example, the article comprises a substrate comprising a metal, a polymer, a polymer composite, or a combination thereof. In some instances, the substrate comprises nickel-plated steel or a coating comprising one or more transition metals, the 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 a combination thereof. In other instances, the article does not include an adhesive or primer between the substrate and the corrosion inhibitor coating composition. The article may be or include a component of an aerospace vehicle or a watercraft, or the article may be or include an exterior surface thereof.

[0027] A method of preparing a corrosion inhibitor coating composition comprises: forming a solution comprising polymerized thiosemicarbazone and a solvent; adding to the solution an ethylene sulfide crosslinker comprising an ethylene sulfide terminated difunctional molecule; and mixing the ethylene sulfide crosslinker with the solution. The method of preparing a corrosion inhibitor coating composition may further comprise the intermediate steps of adding thiourea to the difunctional epoxy terminated molecules in the solution in the presence of a catalyst so as to prepare ethylene sulfide by converting the difunctional epoxy terminated molecules to ethylene sulfide terminated difunctional molecules, and purifying the ethylene sulfide terminated difunctional molecules prior to adding the ethylene sulfide terminated difunctional molecules to the solution. Purification may be accomplished by drying, filtering, evaporating, washing, or any number of separation procedures known to those skilled in the art.

[0028] A difunctional ethylene sulfide molecule is a compound containing two functional groups identified as ethylene sulfide groups. Ethylene sulfide is a three-membered ring consisting of a sulfur atom and two R groups. The two R groups, R and R', represent different substituents or groups attached to the ethylene sulfide ring. Depending on the specific substituents and the reactions they can undergo, difunctional ethylene sulfide molecules can have a variety of chemical properties and applications. Ethylene sulfides are highly reactive species and exhibit characteristic properties that are different from alkyl and aryl sulfides that do not contain three-membered rings. The properties of ethylene sulfides are also different from ethylene oxide or three-membered rings containing oxygen atoms.

[0029] Examples of difunctional ethylene sulfide molecules include molecules based on difunctional, trifunctional or tetrafunctional ethylene sulfides, as well as molecules based on acetophenone, phenolic, aniline resins. Any type of polyepoxide can be converted from having epoxy groups to having ethylene sulfide groups at any level. Epoxides include those based on triols such as glycerol or trishydroxyethyl triisocyanurate. A common tetraol is pentaerythritol. Other polyols include sugars (all types), i.e. monosaccharides (glucose, fructose, etc.), disaccharides (e.g. sucrose) or polysaccharides. Dextrins can also be used. Polyols derived from the condensation of phenol with ketones such as acetone provide bisphenol A. Other substances in this family include bisphenol F (from formaldehyde), bisphenol C (from cyclohexanone), 6F-bisphenol (from hexafluoroacetone), etc. The phenol part of the molecule can also be substituted, such as 2,6-dimethylphenol, or only 2-methylphenol (also known as cresol). Ciba-Geigy MY 720 family epoxy resins can also be used to convert to ethylene sulfides, which are derived from MDA (methylene dianiline) where the two NH2 groups react with excess epichlorohydrin to give a mixture of tri- and tetra-epoxy derivatives. As described herein, in addition to use as a cross-linking agent or to form bridges between polymer chains, possible uses and applications of the bifunctional ethylene sulfide molecules may include chemical synthesis, curing agents, chemical sensing applications, or pharmaceuticals.

[0030] The polymerized thiosemicarbazone molecule can be or include a polymer or macromolecule containing repeating units derived from thiosemicarbazone monomers. Thiosemicarbazones are compounds characterized by the presence of thiosemicarbazone (-C(NH2)(NHR)-S-) functional groups. The polymerization of thiosemicarbazone monomers involves linking these units together to form long chains or networks, thereby producing polymeric materials. Applications of polymerized thiosemicarbazone molecules can be or include metal ion chelation, sensors, catalysis, drug delivery, antimicrobial materials, etc.

[0031] The present invention provides a method of adding epoxy resin and catalyst to the corrosion inhibitor formulation based on thiosemicarbazone, and includes the use of another resin system, for example, a sulfur analog of the same epoxy resin system, which can react with the thioamide of the corrosion inhibitor formulation faster than the original epoxy resin composition. Such improvements allow for reduction of undesirable reactions, lower cure temperatures and reduced demand for catalysts. Conventional catalysts (which can be avoided when using the present invention) may include organotin compounds or small organics such as 2-ethyl-4-methylimidazole or other tertiary amines that may subsequently volatilize and cause coating defects. These common amine catalysts also promote yellowing of some coatings. The composition of the corrosion inhibitor described herein eliminates this problem.

[0032] In the present invention, the use of ethylene sulfide instead of epoxy resin as exemplified by the following chemical formula is the key difference. The three-membered sulfur-containing ring has a lower ring opening barrier than similar molecules with ethylene oxide or epoxy rings.

[0033]

[0034] Other methods for improving the reaction of epoxy resins with some reactive substances require higher temperatures, longer reaction times, and the use of catalysts. These listed concepts have the disadvantage of causing higher production costs, lower productivity, and higher material costs. The composition described herein can also be used in formulations for coating metal parts. The composition can be applied by spraying, dipping, rolling, or other methods known to those skilled in the art. The coated parts can then be dried in a heated oven in an intermittent process or in a heated channel in a continuous process, thereby curing the parts and removing the solvent. Depending on the coating equipment used, the ingredients can be mixed as needed. In addition to aviation aluminum or steel, the corrosion inhibitor coating of the present invention can also be used or coated on a wide range of similar metal surfaces. From small parts to other transport vehicles, containers, and components of rail vehicles or cargo ships can benefit from this coating composition. The application of corrosion inhibitors may cost millions of dollars in both materials and labor, but the exhausted or used coatings will also be discarded after stripping. Creating more durable and more effective coatings can reduce the frequency of maintenance cycles, which results in less labor, less material sent to landfills, and reduces the impact on the global environment. In some examples, remote sensing methods using NIR (near infrared) frequency devices can be used to non-destructively sense coating properties such as thickness or coverage uniformity from 10 to 20 meters away from the test surface.

[0035] The coating composition comprising oligomeric Schiff base corrosion inhibitor (thioamide) as described herein utilizes the alternative means of using or comprising epoxy resin and catalyst, and comprises the use of other resin system, for example, the sulfur analog of identical epoxy resin system, compared with original epoxy resin, it can react with thioamide faster.Although do not wish to be bound by any particular theory, this is considered to allow to reduce undesirable reaction, reduce curing temperature and reduce the demand for catalyst.Sulfur ring opening is faster and opening can lead to the formation of polymer.When used for coating composition, after opening, sulfide group can be well combined and reacted with metal, and has better adhesion.As pointed out, this system is considered to react faster and more completely than epoxy resin, but has similar physical properties and performance.This coating composition can be used for landing gear and other aerospace metals, specifically, Zn-Ni surface, and other materials as described herein.

[0036] Other methods of forming or producing such oligomeric Schiff base corrosion inhibitors (also known as thioamides, thiosemicarbazones or polymeric 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 invention provides similar oligomeric compositions using ethylene sulfide resins or ethylene sulfide crosslinkers in the formation of continuous coatings, wherein the reactive species is combined with a multifunctional resin such as an epoxy resin to form a film having good adhesion to the metal surface, thereby providing a durable corrosion inhibiting composition. In some examples where ethylene sulfide crosslinkers are not used, thiosemicarbazones react slowly and require high temperatures of up to 190°C for curing. Previously known crosslinkers include difunctional epoxy molecules such as diglycidyl bisphenol A, commonly referred to as DGEBA. A typical structure is shown below:

[0037]

[0038] The reactive end groups on the corrosion inhibitor composition of the present invention include, but are not limited to, thioamides. These thioamides, for example, are weakly reactive in nucleophilic attacks on epoxy groups. In some previously considered methods, the addition of a catalyst can be employed, typically at a level of up to 5% by weight of the solids portion of the coating composition. The catalyst used can be or include small, mobile molecules that remain in the coating, which may subsequently migrate or leach out of the coating over time and during use. This catalyst migration may produce defects in the coating, thereby destroying the integrity of the coating. Although the examples of the present coating composition do not contain a catalyst, a certain level of catalyst may be used alternatively in some examples. In other examples, an adhesive may be used in combination with the coating of the present invention or as a pre-treatment step for applying the coating composition of the present invention. In other examples, the coating composition may be applied without a primer or without using a primer.

[0039] An alternative approach is to use another resin system that can react with the thioamide faster than the epoxy functional material.

[0040] The present invention provides sulfur analogs of epoxy resin systems, such as shown in the schematic representation shown below.

[0041]

[0042] The energy barrier for the ring opening of ethylene sulfide is lower than that of any corresponding epoxy resin. This difference is exploited to provide a coating that cures at a lower temperature to provide a coating formulation with lower viscosity, less or no catalyst, and can provide improved adhesion. In addition, the present invention provides a method for converting epoxy functional molecules to produce the corresponding ethylene sulfide using a sulfur donor such as thiourea or potassium thiocyanate. The reagent can be thiourea or potassium thiocyanate, which are readily available and inexpensive. The reaction conditions depend on the system, but can be accomplished by stirring at room temperature (25°C), for example, at reflux for several hours. As illustrative examples, the solvent used can be acetonitrile or a mixture of water and ethanol. All of these are common laboratory reagents and require only a conventional level of safety procedures when used in a laboratory or industrial environment.

[0043] In examples, it has been demonstrated that thiourea is used as a reagent to synthesize ethylene sulfide from epoxides in the presence or absence of ethanol as a solvent. In the absence of ethanol, only certain aromatic or heteroaromatic epoxides react with thiourea, producing ethylene sulfide in a lower yield compared to procedures including the use of potassium thiocyanate (KSCN). The reaction using KSCN is exothermic and may lead to the formation of olefins in some cases. In the presence of weakly hydrated ethanol, the reactivity of thiourea becomes similar to that of KSCN, and olefins will not be formed by furanic epoxides. By these methods, aliphatic and cyclic epoxides can be effectively converted into ethylene sulfide in high yields. Various solvents can affect the reaction results differently, and stable epoxides produce improved results. In some instances, the presence of ethanol can stabilize certain epoxides, prevent desulfurization and help ethylene sulfide to form.

[0044] Substrates for corrosion protection

[0045] The substrate that can be protected from corrosion by the corrosion inhibitor coating composition including the Schiff base oligomer or its combination can be any suitable substrate, such as a metal substrate or a plastic substrate. The metal substrate can include any substrate material whose surface is at least a portion of a metal, such as a portion of a metal on its outer surface. The metal substrate can include any metal that needs to be protected from corrosion. The metal substrate can include a metal or alloy selected from aluminum, such as an aluminum alloy. The metal substrate can be an aluminum alloy, such as an alloy of aluminum and one or more metals selected from the group consisting of copper, magnesium, manganese, silicon, tin, zinc and combinations thereof. The aluminum alloy can be an alloy containing copper. The metal substrate can be a copper-containing alloy, such as a copper-containing aluminum alloy. The amount of copper in the alloy can be about 1% by weight to about 20% by weight, about 1% by weight to about 18% by weight, about 1% by weight to about 10% by weight, or about 1% by weight to about 6% by weight. The aluminum alloy can be an aerospace alloy, such as AA2XXX and AA7XXX types. For example, the aluminum alloy can be AA2024 and AA7075 types. The aluminum alloy can be an automotive alloy, such as AA6XXX types. The aluminum alloy may be a naval alloy, such as type AA5XXX.In an example, the surface metal (eg, the surface metal found in a coating or plating) may be composed of one or more of the foregoing compositions.

[0046] In other substrate examples, metals such as nickel-plated steel, other nickel-plated metals, cadmium-plated metals, or zinc-plated metals may be used, or combinations of any of the described substrate materials may be used. Other transition metal-plated metals or other surfaces may also be suitable substrates. Other examples of suitable substrates may include titanium, aluminum, epoxy resins, or composite panel materials containing metals that would corrode or require a passivating coating in the absence of such coating compositions described herein.

[0047] Composition

[0048] The composition of the present invention may further include a solvent to provide the solubility / dispersibility of the Schiff base oligomer. The solvent may be water, a glycol or a ketone. The glycol may include glycol acetate, such as glycol ether acetate. The ketone may include acetone or pentanone. In some aspects, the solvent may include 1-methoxy-2-propanol acetate, 4-methyl-2-pentanone, acetone, butoxyethanol, dimethylcarbamate or a combination thereof.

[0049] The concentration of the Schiff base oligomer can be from about 0.001 wt % to about 20 wt %, such as from about 0.1 wt % to about 10 wt %, such as from about 1 wt % to about 5 wt %, or from about 5 wt % to about 10 wt %, all relative to the weight of the total solids, and it can provide solubility / dispersibility of the Schiff base oligomer.

[0050] In some aspects, due to the presence of multiple groups capable of interacting with metals in the Schiff base oligomer, the molar ratio of metal in the composition (e.g., metal salt: Schiff base oligomer) provides an excess of metal (e.g., metal salt) compared to the Schiff base oligomer. 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 can 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 can 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 to corrosion inhibitor in the composition can be about 1.1: 1 to about 45: 1, about 1.2: 1 to about 40: 1, about 1.3: 1 to about 35: 1, about 1.4: 1 to about 30: 1, about 1.5: 1 to about 25: 1, about 1.6: 1 to about 20: 1, about 1.7: 1 to about 15: 1, about 1.8: 1 to about 10: 1, about 1.9: 1 to about 9: 1, or about 2: 1 to about 8: 1. In the examples provided herein, the compositions of the present invention are free of metal or substantially free of metal.

[0051] The corrosion inhibitor composition is suitable for use and application to various substrates, such as metal substrates, and can be provided, for example, as a coating composition. The composition can include one or more other additives or corrosion inhibitors suitable for use with the substrate of interest.

[0052] After the composition is deposited on the substrate, the solvent (if used) may be partially, substantially or completely removed by any suitable curing process. For example, the coating composition may be applied to the substrate in a wet or "uncured" condition that dries or cures (i.e., the solvent evaporates) over time. The coating may be dried or cured at ambient temperature or by accelerated means such as ultraviolet light curing systems to form a film or "cured" coating. The coating may also be applied in a semi-cured or fully cured state, such as an adhesive.

[0053] 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 more than one resin, such as an epoxy resin. The coating composition may be a paint composition, such as an epoxy resin paint composition.

[0054] The coating composition may be a powder coating composition, such as a powder coating composition suitable for powder coating of various metal substrates including the aluminum alloys or steel described herein.

[0055] The compositions of the present invention may include more than one additive, such as pigments, fillers, and extenders. Examples of suitable additives that may be combined with the corrosion inhibitors described herein include, for example, adhesives, solvents, pigments (including soluble or insoluble extenders, fillers, corrosion inhibiting pigments, etc.), additives (such as curing agents, surfactants, dyes, amino acids, etc.), etc. Note that some additives may also be appropriately considered as pigments, and vice versa (e.g., matting agents). More specifically, these "additives" include, but are not limited to, glycine, arginine, methionine and amino acid derivatives, such as methionine sulfoxide, methyl sulfoxide and iodide / iodate, gelatin and gelatin derivatives (such as animal and fish gelatin), linear and cyclic dextrins (including α and β cyclodextrins), trifluoromethanesulfonic acid, trifluoromethanesulfonates, acetates, talc, kaolin, organic ion exchange resins (such as organic cation and anion exchange resins), organic ion exchange resins that have been 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, etc.), and combinations thereof.

[0056] The composition may also include other additives, such as rheology modifiers, fillers, toughening agents, heat or UV stabilizers, flame retardants, lubricants, surfactants. The content of additives is generally less than about 10% based on the total weight of the cured composition. Examples include:

[0057] (a) Rheology modifiers, such as hydroxypropylmethylcellulose (e.g., Methocell 311, Dow), modified ureas (e.g., BYK 411, 410) and polyhydroxycarboxamides (e.g., Byk 405);

[0058] (b) film formers, such as esters of dicarboxylic acids (e.g. Lusolvan FBH, BASF) and glycol ethers (e.g. Dowanol, Dow);

[0059] (c) wetting agents, such as fluorochemical surfactants (e.g., 3M Fluorad) and polyether-modified polydimethylsiloxanes (e.g., Byk 307, 333);

[0060] (d) surfactants, such as fatty acid derivatives (e.g. Bermadol SPS2543, Akzo) and quaternary ammonium salts;

[0061] (e) dispersants, for example nonionic surfactants based on primary alcohols (e.g. Merpol 4481, Dupont) and alkylphenol-formaldehyde-disulfide condensates (e.g. Clariants 1494);

[0062] (f) defoaming agents;

[0063] (g) preservatives, for example phosphates (e.g. ADD APT, Anticor C6), alkylammonium salts of (2-benzothiazolylthio)succinic acid (e.g. Irgacor 153CIBA) and triazine dithiol;

[0064] (h) Stabilizers, e.g. benzimidazole derivatives (e.g. Bayer, Preventol BCM, Biocidal Film Protect);

[0065] (i) leveling agents, such as fluorocarbon modified polymers (e.g. EFKA 3777);

[0066] (j) Pigments or dyes, such as fluorescent agents (Royale Pigment and chemicals);

[0067] (k) Organic and inorganic dyes, for example fluorescein;

[0068] (l) Lewis acids such as lithium chloride, zinc chloride, strontium chloride, calcium chloride and aluminum chloride.

[0069] (m) Suitable flame retardants that inhibit flame propagation, heat release and / or smoke generation, which may optionally include any one (or a combination thereof) of the following:

[0070] Phosphorus derivatives, such as molecules containing phosphate, polyphosphate, phosphite, phosphazene and phosphine functional groups, such as melamine phosphate, dimelamine phosphate, melamine polyphosphate, ammonium phosphate, ammonium polyphosphate, pentaerythritol phosphate, melamine phosphite and triphenylphosphine.

[0071] Nitrogen-containing derivatives, for example melamine, melamine cyanurate, melamine phthalate, melamine phthalimide, melam cyanurate, melem cyanurate, melon cyanurate, hexamethylenetetramine, imidazole, adenine, guanine, cytosine and thymine.

[0072] Molecules containing borate functional groups, such as ammonium borate and zinc borate.

[0073] Molecules containing more than two alcohol groups, such as pentaerythritol, polyethylene glycol, polyglycols, and carbohydrates, such as glucose, sucrose, and starch.

[0074] Molecules that absorb heat and release non-flammable decomposition gases, such as metal hydroxides, for example magnesium hydroxide and aluminum hydroxide.

[0075] Expandable graphite.

[0076] Example

[0077] Reaction mechanism of epoxide to ethylene sulfide:

[0078]

[0079] *For extraction

[0080] mechanism:

[0081]

[0082] program:

[0083] 1. In a 25 mL round bottom flask, add EPON828, 5 mL of acetonitrile and 0.152 g of thiourea under stirring. In the exemplary mechanism shown herein, n refers to the number of repeating units representing the specified structure of the EPON828 material, and should be understood as a non-limiting example of the conversion of epoxide to ethylene sulfide. In the non-limiting examples described herein, the average repeating unit is understood to be n=0.2.

[0084] 2. Then, 0.110 g of ammonium cerium nitrate was added under stirring and reflux. The progress of the reaction was monitored using TLC.

[0085] 3. For extraction, prepare a mixture of 10 mL of water and 10 mL of chloroform. Use a separatory funnel.

[0086] 4. The product should enter the chloroform phase, separate and rotary evaporate the chloroform to extract the product. You can add a drying agent such as anhydrous magnesium sulfate to the chloroform solution, then filter and remove the chloroform.

[0087] 5. Repeat the extraction process three times.

[0088] Reaction of ethylene sulfide with Schiff base:

[0089]

[0090] mechanism:

[0091]

[0092] program:

[0093] A 100mL three-necked round-bottom flask with a thermometer installed on the side neck is filled with ethylene sulfide polymer (3.7g). A PTFE stirrer is added and the flask is placed on a magnetic stirrer. 5.0mL MIBK is added and stirring is started. In a 50mL beaker, an inhibitor (1.4g, 0.005mol) is taken and dissolved in 4mL DMF. Under stirring, the inhibitor solution is added dropwise to the flask. Once the inhibitor solvent is added, the reaction mixture becomes yellow. Rinse the beaker with another 1.0mL DMF and add it to the flask. A solution of catalyst DMP-30 (0.014g, 0.000052mol) and 2.0mL MIBK is added to the flask and stirring is continued for 3 hours at room temperature.

[0094] The four active hydrogens from the two -NH2 groups of the inhibitor are believed to participate in the ethylene sulfide ring-opening reaction.

[0095] The catalyst was 1% of the inhibitor molar concentration.

[0096] In addition, the present invention also includes embodiments according to the following clauses:

[0097] 1. A corrosion inhibitor coating composition, comprising:

[0098] polymeric thiosemicarbazones; and

[0099] Ethylene sulfide crosslinker; and

[0100] Wherein, the ethylene sulfide cross-linking agent is a bifunctional molecule.

[0101] 2. The corrosion inhibitor coating composition of clause 1, wherein the polymeric thiosemicarbazone comprises a thiosemicarbazone having the following structure:

[0102]

[0103] 3. The corrosion inhibitor coating composition of any of the preceding clauses, wherein the ethylene sulfide crosslinking agent comprises ethylene sulfide having the following structure:

[0104]

[0105] 4. The corrosion inhibitor coating composition of any of the preceding clauses, wherein the ethylene sulfide crosslinker comprises an aliphatic ethylene sulfide, a trifunctional ethylene sulfide, a bisphenol ethylene sulfide, or a combination thereof.

[0106] 5. The corrosion inhibitor coating composition of any of the preceding clauses, wherein the corrosion inhibitor coating composition does not contain a metal.

[0107] 6. The corrosion inhibitor coating composition of any of the preceding clauses, wherein the corrosion inhibitor coating composition does not contain a catalyst.

[0108] 7. The corrosion inhibitor coating composition of any of the preceding clauses, wherein the ethylene sulfide is present in an amount of about 0.1% to about 5.0% by weight of the total weight of the corrosion inhibitor coating composition.

[0109] 8. An article, comprising:

[0110] Base material;

[0111] A corrosion inhibitor coating composition disposed on a surface of the substrate, the corrosion inhibitor coating composition comprising:

[0112] polymeric thiosemicarbazones; and

[0113] Ethylene sulfide crosslinker; and

[0114] The ethylene sulfide crosslinking agent includes aliphatic ethylene sulfide, trifunctional ethylene sulfide, bisphenol ethylene sulfide or a combination thereof.

[0115] 9. The article of claim 8, wherein the polymeric thiosemicarbazone comprises a thiosemicarbazone having the structure:

[0116]

[0117] 10. The article of clause 8 or 9, wherein the corrosion inhibitor coating composition does not contain a metal.

[0118] 11. The article of any one of clauses 8 to 10, wherein the corrosion inhibitor coating composition does not comprise a catalyst.

[0119] 12. The article of any one of clauses 8 to 11, wherein the corrosion inhibitor coating composition has a thickness of from about 100 nm to about 10 microns.

[0120] 13. The article of any one of clauses 8 to 12, wherein the substrate comprises a metal, a polymer, a polymer composite, or a combination thereof.

[0121] 14. The article of any one of clauses 8 to 13, wherein the substrate comprises nickel-plated steel.

[0122] 15. The article of any one of clauses 8 to 14, wherein the substrate comprises a transition metal.

[0123] 16. The article of any one of clauses 8 to 15, wherein no adhesive or primer is present between the substrate and the corrosion inhibitor coating composition.

[0124] 17. An article as claimed in any one of clauses 8 to 16, wherein the article is a component of an aerospace vehicle or a water vehicle.

[0125] 18. An article as claimed in any one of clauses 8 to 17, wherein the component of the aerospace or watercraft is an outer surface thereof.

[0126] 19. A method of preparing a corrosion inhibitor coating composition, the method comprising:

[0127] forming a solution comprising polymerized thiosemicarbazone and a solvent;

[0128] adding an ethylene sulfide crosslinker comprising ethylene sulfide terminated bifunctional molecules to the solution; and

[0129] The ethylene sulfide crosslinking agent is mixed with the solution.

[0130] 20. A method for preparing a corrosion inhibitor coating composition as described in Clause 19, further comprising:

[0131] Bifunctional epoxy-terminated molecules are added to the solution by thiourea in the presence of a catalyst;

[0132] converting the difunctional epoxy-terminated molecule to an ethylene sulfide-terminated difunctional molecule; and

[0133] The ethylene sulfide-terminated bifunctional molecule is purified and then added to the solution.

[0134] Although the present invention has been explained with respect to more than one embodiment, without departing from the spirit and scope of the appended claims, the illustrated examples may be changed and / or modified. For example, it is understood that although the process is described as a series of behaviors or events, the present invention is not limited by the ordering of these behaviors or events. Some behaviors may occur in different orders and / or occur simultaneously with other behaviors or events other than those described herein. In addition, all processing stages may not be required to implement the method of more than one aspect or embodiment of the present invention. It is understood that structural objects and / or processing stages may be added, or existing structural objects and / or processing stages may be removed or modified. In addition, more than one behavior described herein may be performed in more than one separate behavior and / or stage. In addition, if the terms "include", "comprise", "have" or their variants are used in the detailed description and claims, these terms are intended to be inclusive in a manner similar to the term "include". The term "at least one" is used to indicate that more than one of the listed items can be selected. In addition, in the discussion and claims herein, the term "on" used with respect to two materials, i.e., one material "on" another material, means that there is at least some contact between the materials, while "above" means that the materials are close, but there may be more than one other intervening material, so that contact is possible but not necessary. As used herein, neither "on" nor "above" implies any directionality. The term "conformal" describes a coated material whose angle of the material below is retained by a conformal material. The term "about" means that the listed values ​​can be slightly changed, as long as the change does not cause the process or structure to not conform to the illustrated embodiment. The terms "joined", "connected" and "connected" mean "directly connected" or "connected via more than one intermediate element or member". Finally, the term "exemplary" or "illustrative" means that the description is used as an example and does not mean that it is ideal. Other embodiments of the present invention may be obvious to those skilled in the art by considering the specification and practice of the present invention. It is intended that the description and embodiments be regarded as exemplary only, and the true scope and spirit of the present invention are indicated by the appended claims.

Claims

1. A corrosion inhibitor coating composition, comprising: polymeric thiosemicarbazones; and Ethylene sulfide crosslinker; and in, The ethylene sulfide crosslinking agent is a bifunctional molecule.

2. The corrosion inhibitor coating composition according to claim 1, wherein The polymeric thiosemicarbazones include thiosemicarbazones having the following structure:

3. A corrosion inhibitor coating composition as claimed in any one of the preceding claims, wherein: The ethylene sulfide crosslinking agent includes ethylene sulfide having the following structure:

4. A corrosion inhibitor coating composition as claimed in any one of the preceding claims, wherein: The ethylene sulfide crosslinking agent includes aliphatic ethylene sulfide, trifunctional ethylene sulfide, bisphenol ethylene sulfide or a combination thereof.

5. A corrosion inhibitor coating composition as claimed in any one of the preceding claims, wherein: The corrosion inhibitor coating composition contains no metal.

6. A corrosion inhibitor coating composition as claimed in any one of the preceding claims, wherein: The corrosion inhibitor coating composition does not include a catalyst.

7. A corrosion inhibitor coating composition as claimed in any one of the preceding claims, wherein: The ethylene sulfide is present in an amount of about 0.1% to about 5.0% by weight of the total weight of the corrosion inhibitor coating composition.

8. An article, comprising: Base material; A corrosion inhibitor coating composition disposed on a surface of the substrate, the corrosion inhibitor coating composition comprising: polymeric thiosemicarbazones; and Ethylene sulfide crosslinker; and in, The ethylene sulfide crosslinking agent includes aliphatic ethylene sulfide, trifunctional ethylene sulfide, bisphenol ethylene sulfide or a combination thereof.

9. A method for preparing a corrosion inhibitor coating composition, the method comprising: forming a solution comprising polymerized thiosemicarbazone and a solvent; adding an ethylene sulfide cross-linking agent comprising ethylene sulfide terminated bifunctional molecules to the solution; and The ethylene sulfide crosslinking agent is mixed with the solution.

10. The method for preparing a corrosion inhibitor coating composition according to claim 9, further comprising: Bifunctional epoxy-terminated molecules are added to the solution by thiourea in the presence of a catalyst; converting the difunctional epoxy-terminated molecule into an ethylene sulfide-terminated difunctional molecule; and The ethylene sulfide-terminated bifunctional molecule is purified and then added to the solution.

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