Formulations for surface pretreatment and methods of using the same

Abstract

The present disclosure relates to liquid formulations for treating metal surfaces prior to coating, more specifically to formulations for pre-treating metal surfaces for subsequent coating processes, the formulations comprising at least one mild organic acid or a salt, complex or derivative thereof dissolved in at least one carrier liquid.

Description

Technical Field

[0001] This disclosure relates to formulations for treating metal surfaces prior to coating, and more specifically to formulations for pretreating metal surfaces for subsequent coating processes. Existing background technology

[0002] The following is a list of references considered relevant as background information to the currently published topic: - U.S. Patent Publication No. 5,868,820 -PCT patent application publication number WO 2010077901 The acknowledgment of the above references in this document should not be construed as implying that these references are related in any way to the patentability of the currently disclosed subject matter. Background Technology

[0003] Currently, several technologies for coating metal surfaces with durable coatings are commercially available. For many applications, such as industrial components in machinery, transportation, wire, or building parts, electrophoretic coating and powder coating technologies are used to coat metal surfaces exposed to corrosive conditions during their service life. Water-based or solvent-based coatings are also commonly used on various metal objects.

[0004] To achieve good adhesion between the coating and the metal surface, and to ensure a durable and continuous coating coverage, surface treatment is usually required before coating. Such treatment can involve, but is not limited to, removing various contaminants from the surface (e.g., through degreasing, cleaning, pickling, sandblasting). wait The process involves removal, conditioning (such as depositing substances intended to serve as seed crystals for the next treatment layer), and the formation of a binder layer (such as phosphating, for example with zinc phosphate), which provides a suitable surface structure to increase adhesion to the coating material and allow the coating to be mechanically trapped on the surface. Other materials intended for bonding subsequent layers (including topcoats) may also be applied to the surface. To date, surface treatments for pretreating surfaces for coating, especially powder coating and / or electrophoretic coating, involve complex multi-step methods that often utilize highly toxic and environmentally unfriendly materials, such as corrosive and highly toxic acids. Furthermore, some stages of the treatment require high energy input (e.g., heating the surface and / or the liquid used for the treatment).

[0005] Therefore, there is a need for a more cost-effective and environmentally friendly method for pretreating metal surfaces for coating. Summary of the Invention

[0006] This disclosure provides formulations for pretreating metal surfaces for coating (particularly electrophoretic coating and / or powder coating), which are environmentally friendly, applicable to a wide variety of metal surfaces, and achieve a significant reduction in the complexity and energy / cost input of surface pretreatment methods prior to coating.

[0007] The formulation disclosed herein is designed to alter the surface chemistry of metals and / or increase surface roughness and / or surface area, while achieving this with a relatively short treatment time. For example Within minutes, it simultaneously removes (at least partially removes) various metal oxides and / or other contaminants present on the metal surface that may hinder coating adhesion. This results in a suitable surface for effective adhesion of the treated metal surface to various techniques such as spraying, brushing, dipping, powder coating, and electrophoretic coating. wait The coating formulation is applied. Compared to standard techniques used to date for surface pretreatment, the formulation disclosed herein allows for significant simplification and a reduction in the number of method steps and their energy input, while substantially avoiding the use of toxic and / or hazardous formulation components.

[0008] According to one aspect thereof, this disclosure provides a liquid formulation for treating a metal surface prior to coating, the formulation comprising at least one mild organic acid or its salt, complex or derivative thereof dissolved in at least one carrier liquid.

[0009] Within the context of this disclosure, the terminology coating (or Coating layer ) is intended to indicate the treated surface applied to the metal. Right now A layer or multiple layers of material or formulation applied after treatment with the formulation disclosed herein to impart desired properties to the treated surface. Coating especially Including coating layer, binder layer ( For example (Applied before the coating layer), adhesives, sealants, topcoats wait The coating can be applied to a portion of the surface of the treated metal part or to the entire surface.

[0010] In the formulations disclosed herein, at least one mild organic acid (with or without additional active ingredients) is used to achieve a variety of effects upon its application to a metal surface. Upon contact with the metal surface, the organic acid reacts with metal oxides (and sometimes other generally organic contaminants) present on the metal surface to achieve at least partial decomposition or removal of such metal oxides, thereby at least partially cleaning the metal surface of pre-existing contaminants that are detrimental to subsequent coatings. Furthermore, once the surface metal oxides (and other contaminants) are removed, the mild organic acid and / or its reaction products with the removed oxides (optionally with additional components in the formulation) mildly etch the metal surface, potentially causing an increase in the surface area and roughness of the metal. Such changes in surface area and roughness give the surface a suitable topology to allow for effective mechanical interlocking of coating materials or formulations subsequently applied to the surface. Complexes or transformation products that remain bound to the surface may also contribute anchoring sites and / or suitable morphology to later-stage coating materials applied to the treated surface. Anchoring sites can be achieved through surface adsorption of the active components of the formulation. Anchoring points can also be achieved by altering the chemical properties of the treated surface, thus now incorporating materials suitable for chemical bonding with subsequently applied topcoats. For example Hydrogen-bonded chemical groups.

[0011] Generally, liquid formulations are suitable for treating ferrous metals and alloys (including pure iron, wrought iron, cast steel, carbon steel, and ferro-based alloys that are neither stainless nor stainless steel), aluminum and aluminum alloys. For example 5083, 6061, 5XXX series, 6XXX series wait (This refers to) surfaces of other metals or metal alloys. The metal surface may be galvanized or non-galvanized.

[0012] the term mild organic acids This refers to organic molecules with a typical pKa (in water or aqueous solvents) higher than 0.5 and more typically higher than 2.5. For polyprotic acids, the above values ​​refer to the first (lowest) pKa.

[0013] According to some embodiments, the mild organic acid is selected from: carboxylic acids having one or more carboxyl groups (such as acetic acid, citric acid, oxalic acid, folic acid, and tartaric acid); ethylene glycols and their tautomers, optionally conjugated with a carbonyl group (e.g., ascorbic acid); optionally conjugated carboxylic acids; acidic polymers (“polyacids”), such as organic polymers having sulfonic acid, boric acid, or phosphonic acid side groups; organic compounds having sulfonic acid, boric acid, or phosphonic acid functional groups; acidic polysaccharides, such as alginates or hyaluronic acid conjugated with a carbonyl group, carboxymethyl cellulose, chitosan; phenolic acids with or without electron-withdrawing groups; thiols with or without electron-withdrawing groups; and mixtures thereof.

[0014] According to some embodiments, the mild organic acid is an ethylene glycol conjugated with a carbonyl group.

[0015] According to some preferred embodiments, the mild organic acid is ascorbic acid or a derivative thereof (such as methyl-13-(2-(3,4-dihydroxy-5-oxo-2,5-dihydrofuran-2-yl)-2-hydroxyethoxy)propionate).

[0016] According to other embodiments, the formulation comprises at least one organic antioxidant ( Right now The formulation may contain both mild organic acids and organic antioxidants, provided that the mild organic acid is different from the organic antioxidant.

[0017] the term Organic antioxidants This refers to an organic molecule or substance that interferes with or slows down redox reactions between at least two other materials (e.g., between a reactive oxygen species and its oxidized substrate) and / or acts as an inhibitor of free radical reactions. In the formulations disclosed herein, the organic antioxidant is selected to have a significantly higher standard reduction potential than that of a mild organic acid. For example The difference is at least about 20 mV. According to some embodiments, the difference between the standard reduction potential of the organic antioxidant and the standard reduction potential of the mild organic acid is at least about 50 mV, at least about 100 mV, at least about 150 mV, at least about 200 mV, at least about 250 mV, at least about 300 mV or even higher.

[0018] According to some embodiments, at least one organic antioxidant is selected from polyphenols (including quercetin, catechins, flavonoids), tocopherols (including water-soluble derivatives, such as 6-hydroxy-2,5,7,8-tetramethyl-2-carboxylic acid (Trolox)). TM )), carotenoids ( For example β-carotene, lutein, astaxanthin), terpenes, curcuminoids ( For example Curcumin), saponins, steroids (such as estradiol and estriol), biomolecules (such as bilirubin, uric acid, glutathione), chemicals with π-conjugation along the aromatic and / or polyene molecular structures, and / or chemicals that can make highly stable free radicals formed at sites where chemical bonds are prone to homolytic cleavage.

[0019] When applied to a metal surface, a mild organic acid assists in the destruction of metal oxides on the surface. Metal ions can then be used for complexation, which can be carried out by an antioxidant (in its original or oxidized form), an acid in its neutral or anionic form (in a formulation where the acid and antioxidant are dissimilar components), or with a complexing agent (if present in the formulation, as further described below). With the destruction of the pre-existing metal oxides on the surface, the surface can be accessed by an organic antioxidant and / or a mild acid, which can now react with the metal surface. Such reactions can include mildly etching the metal surface to a desired level of roughness and / or altering the properties of the surface material. Such alterations include the formation of reaction products ( For example (New metal oxides, substances with hydroxyl groups, and complexed organic substances) allow the components of the topcoat to adhere better to the reaction products compared to untreated surfaces.

[0020] The liquid formulation is acidic, with a pH below 7. According to some examples, the formulation is prepared at room temperature (…). Right now It has a pH between about 0.5 and about 6, generally between about 2 and 6, at about 25°C.

[0021] According to some embodiments, the liquid formulation contains at least one auxiliary acid, such as a carboxylic acid (e.g., acetic acid, propionic acid), a phenolic acid (e.g., polyphenolic acid, hydroxybenzoic acid), a hydroxycinnamic acid (e.g., ferulic acid), and other acids, the auxiliary acid being different from the mild organic acid.

[0022] In some embodiments, the liquid formulation comprises at least about 0.1% by weight of the at least one mild organic acid.

[0023] In other embodiments, the liquid formulation contains between about 0.3% by weight and 30% by weight of the at least one mild organic acid.

[0024] In some embodiments, the liquid formulation comprises at least about 0.1% by weight of the at least one organic antioxidant.

[0025] In other embodiments, the liquid formulation contains between about 0.3% by weight and 30% by weight of the at least one organic antioxidant.

[0026] carrier liquid Typically, the carrier liquid is a polar and / or protic solvent, allowing at least one mild organic acid and / or organic antioxidant to dissolve therein. According to some embodiments, at least one carrier liquid is selected from water, alcohols, amines, polymers such as polyethers (optionally further functionalized) that have sufficient fluidity at ambient temperature, liquid ions, and mixtures thereof.

[0027] According to some embodiments, at least one carrier liquid is an aqueous liquid. According to other embodiments, at least one carrier liquid is water.

[0028] Liquid formulations may further comprise at least one auxiliary antioxidant according to some embodiments. Without being bound by theory, the auxiliary antioxidant can function to modify the rate and / or yield of the organic antioxidant reaction and to adapt the formulation to various substrate types and / or final surface reaction products. It can also function to extend the shelf life of the formulation during storage.

[0029] According to some embodiments, at least one auxiliary antioxidant is selected from tocopherols (including water-soluble derivatives, such as 6-hydroxy-2,5,7,8-tetramethylchromo-2-carboxylic acid), carotenoids ( For example β-carotene, lutein, astaxanthin), terpenes, curcuminoids ( For example Curcumin), saponins and steroids (such as estradiol and estriol), other biomolecules (such as bilirubin, uric acid, glutathione), chemicals with π-conjugation along aromatic and / or polyene molecular structures and / or chemicals that can highly stabilize free radicals formed at sites where chemical bonds are easily formed, and combinations thereof, provided that the auxiliary antioxidant is different from organic antioxidants and different from mild organic acids.

[0030] According to some embodiments, the formulation comprises at least about 0.01% by weight of the at least one auxiliary antioxidant. According to other embodiments, the liquid formulation comprises between about 0.1% by weight and about 30% by weight of the at least one auxiliary antioxidant.

[0031] According to some embodiments, the weight ratio (w / w) of the mild organic acid to the auxiliary antioxidant is between about 1:100 and about 100:1.

[0032] According to some embodiments, the weight ratio (w / w) of the organic antioxidant to the auxiliary antioxidant is between about 1:100 and about 100:1.

[0033] Liquid formulations may further comprise at least one complexing agent according to some embodiments. The complexing agent reacts with and / or binds to one or more of metal ions or metal oxides to facilitate changes in surface morphology and / or assist in the decomposition of metal-containing substances on untreated surfaces and / or the formation of anchoring sites on the surface. Anchoring sites can also be achieved through surface adsorption of the complexing agent. Anchoring sites are sites on the surface where materials in the topcoat can bind to achieve the desired adhesion between the topcoat and the metal surface. While the complexing agent may possess some antioxidant activity, it should be noted that within the scope of this disclosure, the complexing agent exhibits significantly lower antioxidant activity compared to mild organic acids and / or organic antioxidants, while possessing increased complexing ability with ionic metal substances or neutral metal surfaces.

[0034] According to some embodiments, at least one chelating agent is selected from polyphenols (including quercetin, catechins, flavonoids, tannins), tocopherols (including water-soluble derivatives, such as 6-hydroxy-2,5,7,8-tetramethylchromo-2-carboxylic acid), carotenoids ( For example β-carotene, lutein, astaxanthin), terpenes, curcuminoids ( For example Curcumin), saponins, steroids (such as estradiol and estriol), other biomolecules (such as bilirubin, uric acid, glutathione), other chemicals with π-conjugation along the aromatic and / or polyene molecular structures and / or chemicals capable of highly stabilizing free radicals formed at sites where chemical bonds are readily cleaved, polyethers (including crown ethers) and polyvinyl alcohol, polysaccharides, polyamines, polyureas, polyvinyl alcohol, acrylates, polyepoxides, polysulfones, polystyrene, polyesters, polyamides, polyphenols, and / or small chelating molecules such as: amino polycarboxylates (most notably EDTA), iminodisuccinic acid (IDS), S,S-ethylenediamine-N,N'-disuccinic acid (EDDS), L-glutamic acid N,N-diacetic acid (GLDA), methylglycine diacetic acid (MGDA), amino polycarboxylates, nitrotriacetic acid (NTA), polyaspartic acid, combinations thereof, or derivatives thereof, provided that the chelating agent is different from the said mild organic acid and / or the said organic antioxidant.

[0035] According to some embodiments, the formulation comprises at least about 0.01% by weight of the at least one complexing agent. According to other embodiments, the liquid formulation comprises between about 0.1% by weight and about 30% by weight of the at least one complexing agent.

[0036] Depending on the desired application method, the viscosity of a liquid formulation can be modified by adding one or more viscosity modifiers. Viscosity modifiers function to increase or decrease the viscosity of the liquid formulation.

[0037] According to some embodiments, the formulation comprises at least one gelling agent. gelling agentA gelling agent is an agent capable of changing the viscosity of a liquid formulation to a desired viscosity. Generally, gelling agents form a thin film when applied to a metal surface, thereby increasing the residence time of the formulation on the metal surface and / or aiding in achieving the desired surface modification. Gelling agents can form 3D networks of macromolecules, such as viscoelastic networks of polymer chains, thereby trapping mild organic acids and other components (if present) within the network structure. This physical trapping prolongs the contact time of mild organic acids with the metal surface and thus increases the efficiency of the formulation. Furthermore, gelling agents can act to increase the stability of the formulation (…). For example This prevents the precipitation of antioxidants during storage, thereby increasing the shelf life of the formulation. Furthermore, the 3D network or film formed with the assistance of a gelling agent can serve as a substrate for bonding the desired coating.

[0038] Gelling agents can be selected from water-soluble or colloidal water-soluble polymers (hydrocolloids), such as modified cellulose ( For example Hydroxyethylcellulose, methylcellulose, hydroxypropylmethylcellulose) and other polysaccharides, polyvinyl alcohol, polyquaternium-10, guar gum, hydroxypropyl guar gum, xanthan gum, gellan gum, aloe vera gel, amia, carrageenan, oat flour, starch and modified starch, gelatin, solanum, gum arabic, inulin, konjac gum, locust bean gum, fenugreek gum, marshmallow root, pectin and modified pectin, solagum, astragalus gum (TG). wait .

[0039] The gelling agent can be selected from one or more polymers, such as acrylic acid / ethyl acrylate copolymers, carboxylated vinyl polymers (... For example Carbomer resin, polyethylene, polyolefin polyether crosslinked acrylic polymer, hydrophobically modified crosslinked acrylic polymer, etc.

[0040] According to some embodiments, the gelling agent may be selected from xanthan gum, gellan gum, sodium alginate, pectin, low- or high-methoxyl pectin, chitosan, polyvinyl alcohol, and mixtures thereof.

[0041] According to some embodiments, the formulation contains at least one gelling agent at a concentration ranging from about 0.001% by weight to about 10% by weight.

[0042] According to some embodiments, the formulation has a viscosity between about 0.5 and 1500 mPa·s.

[0043] According to some embodiments, the formulation further comprises at least one functional additive selected from the following: surfactants, emulsifiers, dispersants, defoamers, surface binders, antimicrobial agents, bactericides, binders, colorants, flavor enhancers, odor masking agents, UV stabilizers, flame retardants, and other agents.

[0044] According to another aspect, this disclosure provides a method for treating a metal surface prior to coating, the method comprising applying the liquid formulation disclosed herein to the metal surface for a period of time sufficient to achieve desired surface properties.

[0045] According to some embodiments, this time period is sufficient to at least partially remove the metal oxide from the metal surface.

[0046] According to other embodiments, this time period is sufficient to increase the roughness of the metal surface and / or to form the minimum amount of chemical substances required for adequate adhesion between the topcoat and the surface.

[0047] According to other embodiments, this time period is sufficient to allow the components in the formulation to undergo a chemical reaction with the metal surface in order to form beneficial reaction products (such as certain metal oxides or other chemical substances (whether inorganic or organic) or their complexes) to a degree sufficient to bond the desired topcoat.

[0048] According to some embodiments, this time period is between about 5 seconds and about 600 seconds. Therefore, compared with known methods, the method of this disclosure allows one or more of the following to be achieved within a relatively short contact time between the formulation and the metal surface: increasing the surface area of ​​the metal surface, at least partially removing metal oxides from the metal surface, and increasing the roughness of the metal surface to form a beneficial surface substance.

[0049] According to some embodiments, the liquid formulation is maintained at a temperature between about 1°C and about 80°C during the application. According to some embodiments, the liquid formulation is applied to the metal surface by dipping, brushing, or spraying.

[0050] According to some embodiments, the method is a continuous method.

[0051] According to some embodiments, this method is an industrial method. Such methods can be standalone methods or can be incorporated as process steps into large-scale production lines for producing treated metal parts.

[0052] According to some embodiments, the method is tailored to provide successive pre-coating processes for multiple metal objects in a sequential manner.

[0053] According to some embodiments, after the stated time period, the formulation is typically removed from the metal surface by dripping the formulation and / or blowing it off with or without auxiliary heating (such as with an air knife) and / or washing it off with water or an aqueous liquid. This washing can be performed by immersion in a liquid bath, or one or more successive baths.

[0054] According to some embodiments, after the formulation has been applied to the metal, the treated metal is heated to a temperature suitable for electrophoretic coating and / or powder coating processes. Typical temperatures are in the range of about 60°C to about 280°C.

[0055] Since the metal parts or components to be treated are typically machined or molded prior to surface treatment, it may be desirable to remove any lubricant or other treatment residues, particularly oily or greasy residues, from the metal surface before surface treatment. Therefore, in some embodiments, the method further includes degreasing the metal surface prior to the application of a liquid formulation.

[0056] According to some embodiments, the liquid formulation is suitable for use on various metal parts of structural components with different finishes or surface properties, such as rolled oxide scale, galvanized steel, aluminum parts, weld areas, and soft solder areas. wait .

[0057] According to some embodiments, the liquid formulation is applied to the surface of the metal once before coating with a coating formulation or coating material.

[0058] According to other embodiments, the formulation may be applied two or more times, wherein excess formulation or byproducts are optionally washed away or removed between applications. In each such application cycle, the liquid formulation is allowed to remain in contact with the metal surface or the previously applied layer for the duration stated. When performing such cyclic applications, the liquid formulation applied in each cycle may be the same (…). Right now (having the same composition) or different ( Right now In each cycle, different liquid formulations of this disclosure are applied, for example, in mild organic acids and / or organic antioxidants, at varying concentrations and in the presence of co-antioxidants. wait (Different aspects).

[0059] According to another aspect, a method for treating a metal surface prior to coating is provided, the method comprising: (a) Degreasing a metal surface by applying one or more degreasing compositions; (b) Cleaning the metal surface to remove one or more degreasing compositions; (c) Applying a liquid formulation as disclosed herein to the metal surface for a duration sufficient to produce a sufficiently high concentration of the desired surface substance as a product of the chemical reaction between the formulation and the surface and / or to modify the topology of the metal surface; and (d) After the time period, the liquid formulation is removed to obtain a metal surface ready for coating.

[0060] According to another aspect, a method for obtaining a coated metal surface is provided, the method comprising: (A) Degreasing a metal surface by applying one or more degreasing compositions; (B) Cleaning the metal surface to remove one or more degreasing compositions; (C) Applying a liquid formulation as disclosed herein to the metal surface for a period of time sufficient to produce a sufficiently high concentration of the desired surface substance as a product of the chemical reaction between the formulation and the surface and / or to modify the topology of the metal surface. (D) After the said time period, remove the liquid formulation to obtain a metal surface ready for coating; and (E) Apply one or more coatings to the metal surface of step (D).

[0061] According to another aspect, a method for obtaining a coated metal surface is provided, the method comprising: (A') Degreasing a metal surface by applying one or more degreasing compositions; (B') Clean the metal surface to remove one or more degreasing compositions; (C') Applying the liquid formulation as disclosed herein to the metal surface for a period of time sufficient to modify the topology of the metal surface; and (D') Apply one or more coatings to the metal surface of step (C').

[0062] As used herein, unless the context clearly indicates otherwise, the singular form "a," "an," "a," "a" is used in the sense of a singular form. A sort of "as well as" The / described "Including plural indicators."

[0063] As used herein, terminology about This is intended to cover deviations of ±10% from the specifically mentioned values ​​of parameters (such as concentration, temperature, pH, etc.).

[0064] Whenever a range of numbers is indicated in this document, that range is intended to include any referenced numbers (fractions or integers) within the indicated range. The phrase "first indicating number" and "second indicating number" are used interchangeably. Range of variation / scope The terms “from the first indicated digit to the second indicated digit” and “range of variation” are used interchangeably herein and are intended to include the first indicated digit, the second indicated digit, and all fractions and integers therebetween. It should be noted that in the use of given ranges to describe various embodiments, such ranges are given merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention. Therefore, the description of the ranges should be considered as having specifically disclosed all possible subranges and the individual values ​​within those ranges.

[0065] Throughout this specification and the appended claims, unless the context otherwise requires, the term "..." Include (comprise) "and variations (such as " Includes "and" Comprising "" should be understood as implying the inclusion of the integer or step or a group of integers or steps, but not excluding any integer or step or a group of integers and steps.

[0066] Generally, it should be noted that the terms used in any component of the formulations, processes, and / or methods described in this disclosure are subject to change. "...at least one..." It should be understood that this includes one, two, three, four or even more different appearances of the components described in the formulations, processes and / or methods of this disclosure.

[0067] It should be understood that, for clarity, certain features of this disclosure described in the context of a single embodiment may also be provided in combination in a single embodiment. Conversely, for brevity, various features of this disclosure described in the context of a single embodiment may also be provided individually or in any suitable sub-combination or, where appropriate, in any other described embodiment. Certain features described in the context of different embodiments should not be considered as essential features of those embodiments unless the embodiments would not function without those elements.

[0068] This is publicly available. method This involves numerous methodological steps, which may or may not be associated with other common physicochemical processes to achieve the desired result. Unless otherwise indicated, such methodological steps (if present) may be arranged in a different order without affecting the feasibility of the method or its effectiveness in achieving the desired end result. Attached Figure Description

[0069] To better understand the subject matter disclosed herein and to illustrate how it is implemented in practice, the implementation scheme will now be described by way of non-limiting example only, with reference to the accompanying drawings, in which: Figures 1A to 1B To compare the steel treated with the formulation of this disclosure with a reference electrophoretic coating sample ( Figure 1A ) and aluminum ( Figure 1B A thermogram of the degree of rust on the electrophoretic coated test samples. The range is 5 (rust) to 10 (no rust observed). Results are shown for 60 CCT cycles.

[0070] Figures 2A to 2C For steel treated with the formulation disclosed herein ( Figure 2A ), galvanized steel ( Figure 2B ) and aluminum ( Figure 2C A thermal map of the degree of rust on powder-coated test samples. The range is 5 (rust) to 10 (no rust observed). Results are shown for 60 CCT cycles.

[0071] Figures 3A to 3D Images of powder-coated steel samples treated with the formulations of this disclosure after immersion testing: front and back images at room temperature for 96 hours. Figures 3A to 3B ), and front and back images after 120 hours at 49°C ( Figures 3C to 3D ).

[0072] Figures 4A to 4D SEM image of carbon steel: untreated surface ( Figure 4A ), surfaces treated with organic antioxidants in acidic solutions ( Figure 4B The image shows the newly formed submicron structure and the etching of both, on a surface treated with two organic antioxidants in an acidic solution. Figure 4C ), and surfaces treated in acidic solutions with solutions containing antioxidants and dispersants ( Figure 4D ).

[0073] Figures 5A to 5B For the electrochemical impedance spectroscopy results of pickled steel surfaces treated with the formulations disclosed herein: Figure 5A The effect of drying time (0, 30, 90, and 120 seconds) is shown. Figure 5B The effects of different test formulations are shown.

[0074] Figures 6A to 6B For the application of oxygen atoms to untreated and carbon steel samples treated with formulations according to this disclosure. Figure 6A ) and iron atoms ( Figure 6B XPS results. Detailed Implementation

[0075] The formulations disclosed herein are prepared by mixing an acidic organic antioxidant in an aqueous carrier liquid with one or more auxiliary antioxidants and optionally with one or more additives.

[0076] Table 1: Exemplary formulation

[0077] To demonstrate the efficacy of surface treatments using the formulations disclosed herein, comparative studies were performed relative to standard zinc phosphate and / or sandblasting standard treatments.

[0078] Sample pretreatment: Thin sheet samples of steel, galvanized steel, and aluminum alloy, measuring 75 mm × 150 mm, were used for testing. The samples were degreased by immersion in a degreasing solution, then rinsed with water and dried, followed by any of the following: (1) Immerse in the formulation according to this disclosure for 90 seconds. (2) Treated by standard zinc phosphate treatment, or (3) Sandblasting.

[0079] Samples treated with the formulations disclosed herein are either electrophoretically coated or powder coated. Reference electrophoretically coated samples were treated with zinc phosphate, while reference powder-coated steel and aluminum samples were sandblasted prior to coating. Both electrophoretically and powder coating were performed according to industry standard coating procedures.

[0080] Environmental testing The coated samples underwent cyclic corrosion testing (CCT) in an Ascott CC1000IP test chamber. The CCT procedure was based on SAE J2334 Method C, which simulates accelerated corrosion conditions. Each cycle included a sequence of the following steps: - Humid phase: 50℃, 100% humidity, 6 hours - Salt spray application phase: 15 minutes -Drying stage: 60℃, 50% RH, 17 hours and 45 minutes.

[0081] Samples were analyzed after 500, 1000, 1500, and 2000 hours. Samples were imaged before environmental testing and at each testing time point. All imaging was performed in a designated imaging chamber equipped with a 20MP industrial computer vision camera (Triton from LUCID Vision Labs).

[0082] Each coated sample was evaluated as follows (Table 2): Table 2: Sample evaluation metrics

[0083] result Electrophoretic coating samples Figures 1A to 1B The graphs showing the rust index are compared to a reference sample (zinc phosphate treatment) with the tested steel and aluminum samples treated with the formulation of this disclosure. It can be seen that no significant rust was observed after 60 CCT cycles (SAE J 2334), indicating that the formulation of this disclosure provides a surface finish at least as good as the standard zinc phosphate treatment.

[0084] The results of the cross-cut test, bubbling test, and rusting test are shown in Table 3.

[0085] Table 3: Cross-cut test, blistering, and rusting of electrophoretic coated samples, for 60 CCT cycles.

[0086] As can be seen, samples treated with the formulation of this disclosure exhibit the same results as reference samples surface-treated with standard zinc phosphate, demonstrating that the formulation of this disclosure can replace industry-standard zinc phosphate treatment to significantly simplify surface treatment methods prior to electrophoretic coating and potentially eliminate the use of such toxic components in this method. This formulation provides prevention of surface corrosion, blistering, cracking, peeling, and other defects while maintaining good adhesion of the topcoat to steel, aluminum, and galvanized steel surfaces.

[0087] Powder Coated Samples Figures 2A to 2C The graphs showing the rust index are compared to a reference sample (sandblasted) with test steel, galvanized steel, and aluminum samples treated with the formulation of this disclosure. It can be seen that no significant difference in rust was observed over 60 CCT cycles (SAE J 2334), indicating that the formulation of this disclosure provides good surface treatment with and without sandblasting.

[0088] The results of the cross-cut test, blistering test, and rusting test for 60 CCT cycles are shown in Table 4.

[0089] Table 4: Cross-cut test, blistering, and rusting of powder-coated samples, 60 CCT cycles

[0090] As shown in Table 4, the samples treated with the formulation of this disclosure exhibited the same results as the reference samples surface-treated by standard sandblasting. This demonstrates that the formulation of this disclosure can replace industrial standard sandblasting to significantly simplify the surface treatment method prior to electrophoretic coating and potentially eliminate the use of such toxic components in this method. The formulation provides prevention of surface corrosion, blistering, cracking, peeling, and other defects while maintaining good adhesion of the topcoat to steel, aluminum, and galvanized steel surfaces.

[0091] from Figures 2A to 2C As can be seen, the coating remains intact, with no evidence of blistering, rusting, or impact on adhesion. Therefore, the formulation disclosed herein provides a surface treatment at least equivalent to industry-standard pretreatments prior to coating. However, unlike the corrosive treatments currently performed on surface pretreatments for coating, the formulation disclosed herein is safer for the applicator and more environmentally friendly, while requiring less energy input for application and fewer steps in the pretreatment process compared to standard surface pretreatment methods such as sandblasting or zinc phosphate treatment.

[0092] Characterization of the treated samples The effect on the surface topology obtained on metal surfaces by the formulations disclosed herein was evaluated, such as... Figures 4A to 4DAs can be seen in these figures, they show scanning electron microscope (SEM) images of metal surfaces.

[0093] The steel samples were thoroughly cleaned with water and organic solvents and then vacuum dried. Each sample was then immersed in a different formulation from Table 1 for 100 seconds.

[0094] It can be seen that the untreated surface ( Figure 4A ) exhibits a relatively smooth surface, with the defects and machining marks typically expected. Surfaces treated with organic antioxidants in an acidic solution ( Figure 4B The surface exhibits both newly formed submicron structures and etching. The surface treated with two organic antioxidants in an acidic solution ( Figure 4C Surfaces exhibited significantly less etching but more pronounced micron and submicron surface structures. Surfaces treated with a solution containing several antioxidants and a dispersant in an acidic solution showed significant surface coverage of submicron structures. Figure 4D Therefore, the formulations disclosed herein have been shown to effectively modify the surface structure of metal surfaces, making them suitable for subsequent coating processes.

[0095] Treatment with the formulations according to Table 1 and under different drying conditions ( Figure 5A Drying under different formulations disclosed herein ( ) and using different formulations disclosed herein ( ) Figure 5B Electrochemical impedance spectroscopy (EIS) was performed on pickled steel samples treated with [treatment name missing]. Measurements were taken between 1 Hz and 0.8 MHz. Figures 5A to 5B It can be seen that the treatment in the exemplary formulation reduces the resistivity of the metal surface, which in turn enables a shorter energizing duration in the electrostatic coating process and supports the finding that the surface properties have been altered by the treatment.

[0096] XPS Analysis To evaluate the effect of the agent on the metal surface immediately after application, X-ray photoelectron spectroscopy (XPS) was performed on treated and untreated metal samples as follows.

[0097] The carbon steel sample (without rolled oxide scale or rust, but with a protective grease layer) (accepted as is) was immersed in a standard commercial degreasing solution for 1 minute and then rinsed twice with distilled water.

[0098] Some samples were then immersed in the formulation according to Table 1 above for 3 minutes (“Samples”), while other samples were left untreated with the formulation (“Reference”). Both types of samples were then cleaned by immersion in a first distilled water container (30 seconds), immersion in a second distilled water container (30 seconds), followed by rinsing with ethanol and isopropanol streams and drying under pressurized gas flow for 2 minutes. Both types of samples were then transferred to a high vacuum (<10) -5(Continue for 16 hours to evaporate the residue of solvent or loosely bound substances from the surface.)

[0099] Then in the analysis chamber (UHV-210 during analysis) -10 The sample was analyzed by XPS using a Versaprobe III – PHI instrument (PHI, USA). A focused AlKα monochromatic X-ray source (1486.6 eV) was used to irradiate the sample using an X-ray beam (100 μm, 25 W, 15 kV). The emitted photoelectrons were guided to a spherical capacitor analyzer (SCA). Sample charge was compensated by dual-beam charge neutralization based on a combination of a conventional electron diffuser gun and a low-energy argon ion beam.

[0100] Table 5 details the surface investigation of the samples.

[0101] Table 5: Element percentage by type on the surface of the sample

[0102] It can be seen that treating metals with this formulation leads to an increase in the amount of oxygen atoms present on the surface and a decrease in the thickness of the organic layer on the metal surface—as evidenced by the high percentage of iron atoms exposed on the surface of the sample.

[0103] Figure 6A Analysis of oxygen atoms on the surface of the samples was provided. It can be seen that the samples treated with this formulation exhibited higher levels of iron oxides and hydroxides on their surfaces. These substances could act as potential sites for chemical bonding with materials in the topcoat.

[0104] Figure 6B Analysis of iron atoms on the sample surface was provided. It can be seen that the treated sample exhibits a higher presence of iron oxides formed on its surface compared to the untreated sample. Such substances could serve as potential sites for chemical bonding with materials in the topcoat.

[0105] The results clearly show that the surface of the treated sample was significantly altered compared to the untreated sample. This alteration was significant enough to withstand repeated washing and exposure to high vacuum, indicating that a chemical transformation had occurred on the surface.

[0106] The layer formed by treatment with the disclosed solution is apparently very thin, possibly on the order of several nanometers, as indicated by the observed signal of unoxidized iron, demonstrating the formulation's potential ability to assist in the removal of lubricating coatings from metal surfaces. Furthermore, as is known, residues of lubricating material can hinder topcoat coverage and adhesion to metal surfaces; replacing these with other organic components derived from the formulation could potentially promote rather than hinder the adhesion of the treated topcoat.

[0107] Treatment with this formulation has been shown to promote the formation of an iron oxide-rich layer, indicating that the formulation promotes metal oxidation. The layer formed by the treatment was found to be rich in oxygen atoms and hydroxide groups. Such layers provide surface binding sites that promote strong adhesion between the topcoat and the surface, for example, through hydrogen bonding between these sites and functional groups in the topcoat molecules / polymers. Furthermore, such layers can potentially provide protection against surface corrosion due to the formation of surface oxides and / or due to the binding of organic matter from the formulation to the metal surface.

Claims

1. A liquid formulation for treating a metal surface prior to coating, said formulation comprising at least one mild organic acid or its salt, complex or derivative thereof dissolved in at least one carrier liquid.

2. The liquid formulation according to claim 1, wherein the at least one mild organic acid is selected from: carboxylic acids having one or more carboxyl groups; olefinic alcohols and their tautomers, optionally conjugated with a carbonyl group; optionally conjugated carboxylic acids; sugars; acidic polymers; organic compounds having sulfonic acid, boric acid or phosphonic acid functional groups; acidic polysaccharides; phenolic acids with or without electron-withdrawing groups; and thiols with or without electron-withdrawing groups.

3. The liquid formulation according to claim 1 or 2, wherein the mild organic acid is an olefinic alcohol conjugated with a carbonyl group.

4. The liquid formulation according to any one of claims 1 to 3, wherein the mild organic acid is ascorbic acid or a derivative thereof.

5. The liquid formulation according to any one of claims 1 to 4, comprising at least about 0.1% by weight of the at least one mild organic acid.

6. The liquid formulation according to claim 5, comprising between about 0.3% by weight and 30% by weight of the at least one mild organic acid.

7. The liquid formulation according to any one of claims 1 to 6, wherein the formulation further comprises at least one organic antioxidant.

8. The liquid formulation according to claim 7, wherein the organic antioxidant is selected from polyphenols, tocopherols, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid, carotenoids, terpenes, curcuminoids, saponins, steroids, bilirubin, uric acid, glutathione, chemicals having π-conjugation along the aromatic and / or polyene molecular structure, chemicals capable of highly stabilizing free radicals formed at sites where homolytic cleavage of chemical bonds is likely to occur, and combinations thereof, provided that the organic antioxidant is different from the mild organic acid.

9. The liquid formulation according to 7 or 8, comprising at least about 0.1% by weight of the at least one organic antioxidant.

10. The liquid formulation according to claim 9, comprising between about 0.3% by weight and 30% by weight of the at least one organic antioxidant.

11. The liquid formulation according to any one of claims 1 to 10, wherein the at least one carrier liquid is a polar and / or proton liquid.

12. The liquid formulation of claim 11, wherein the at least one carrier liquid is selected from water, alcohol, amine, polymer having sufficient fluidity at ambient temperature, liquid ions, and mixtures thereof.

13. The liquid formulation according to claim 12, wherein the at least one carrier liquid is an aqueous liquid.

14. The liquid formulation according to claim 13, wherein the at least one carrier liquid is water.

15. The liquid formulation according to any one of claims 1 to 14, further comprising at least one auxiliary antioxidant.

16. The liquid formulation of claim 15, wherein the at least one auxiliary antioxidant is selected from tocopherol, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid, carotenoids, terpenes, curcuminoids, saponins, steroids, bilirubin, uric acid, glutathione, and chemical substances having π-conjugation along the aromatic and / or polyene molecular structure, chemical substances capable of highly stabilizing free radicals formed at sites where homolytic cleavage of chemical bonds is readily possible, and combinations thereof, provided that the auxiliary antioxidant is different from the organic antioxidant and different from the mild organic acid.

17. The liquid formulation according to claim 15 or 16, wherein the formulation comprises at least about 0.01% by weight of the at least one auxiliary antioxidant.

18. The liquid formulation of claim 17, comprising between about 0.1% and 30% by weight of the at least one auxiliary antioxidant.

19. The liquid formulation according to any one of claims 1 to 18, having a pH between about 0.5 and about 6.

20. A method for treating a metal surface prior to coating, the method comprising applying a liquid formulation according to any one of claims 1 to 19 to the metal surface for a period of time sufficient to modify the topology of the metal surface.

21. The method of claim 20, wherein the time period is sufficient to at least partially remove the metal oxide from the metal surface.

22. The method of claim 20 or 21, wherein the time period is sufficient to increase the roughness of the metal surface and / or to form the minimum amount of chemical substance required for adequate adhesion of the topcoat to the surface.

23. The method according to any one of claims 20 to 22, wherein the time period is between about 5 seconds and about 600 seconds.

24. The method according to any one of claims 20 to 23, wherein the liquid formulation is maintained at a temperature between about 1°C and about 80°C during the application.

25. The method according to any one of claims 20 to 24, wherein the application is performed by dipping, brushing, or spraying.

26. The method according to any one of claims 20 to 25, wherein the metal surface is degreased prior to the application.

27. The method according to any one of claims 20 to 26, wherein the formulation is removed from the metal surface after the said time period.

28. A method for treating a metal surface prior to coating, the method comprising: (a) Degreasing the metal surface by applying one or more degreasing compositions; (b) Clean the metal surface to remove the one or more degreasing compositions; (c) Applying the liquid formulation according to any one of claims 1 to 19 to the metal surface for a period of time sufficient to modify the topology of the metal surface; as well as (d) After the time period, the liquid formulation is removed to obtain a metal surface ready for coating.

29. A method for obtaining a coated metal surface, the method comprising: (A) Degreasing the metal surface by applying one or more degreasing compositions; (B) Clean the metal surface to remove the one or more degreasing compositions; (C) Applying the liquid formulation according to any one of claims 1 to 19 to the metal surface for a period of time sufficient to modify the topology of the metal surface; (D) Remove the liquid formulation after the time period to obtain a metal surface ready for coating; as well as (E) Apply one or more coatings to the metal surface of step (D).

30. A method for obtaining a coated metal surface, the method comprising: (A') Degreasing the metal surface by applying one or more degreasing compositions; (B') Clean the metal surface to remove the one or more degreasing compositions; (C') Applying the liquid formulation according to any one of claims 1 to 19 to the metal surface for a period of time sufficient to modify the topology of the metal surface; and (D') Apply one or more coatings to the metal surface of step (C').

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