, Description:TECHNICAL FIELD
The present disclosure relates to the field of metallic coatings. Particularly, the present disclosure relates to two component coating compositions for metallic substrates, methods for preparing said coating compositions, use of said coating compositions for coating metallic substrates and metallic substrates obtained therefrom.

BACKGROUND OF THE DISCLOSURE
Corrosion of metallic substrates is an unavoidable phenomenon which is mitigated by providing protective films, laminations, oil, grease, and similar coatings. Metallic coatings can be provided either in sacrificial form or barrier form.

Metals nails are made of stainless steel, aluminum, iron, copper and bronze. These nails, especially iron and copper nails, have the tendency of quick rusting during transportation and storage. There are several methods to protect iron nails from corrosion such as electroplating of copper, galvanizing, and the like. However, these methods make the iron nails very expensive.

US686654A describes a development of gum-arabic, rosin, and linseed-oil in the proportions of ten parts by weight of the rosin to one part each of the gum-arabic and linseed oil. This composition provides the corrosion protection. US3488202A discloses a linseed oil emulsion-based paints for water resistance comprising reduced levels of non-ionic emulsifiers.

EP0648485A1 discloses a cosmetic nail varnish comprising polyester-polyurethane particles in a dispersed state in the proportion of 3 -50 % by weight of the varnish, preferably in the proportion of 10 -50 % by weight of the varnish. Varnish contains at least one organic or inorganic pigment in the range of 0.01 to 5%, preferably 0.5 to 2% of total varnish, one water soluble fluorinated surfactant, wetting/dispersing agent, a dispersing agent, a defoamer, a sunscreen, a preservative, a drying accelerator, a wax, a silicone.

WO1999040893A1 relates to a cosmetic composition comprising a new thickening system comprising a non-ionic polyurethane and non-ionic polymers with fatty chains.

FR2782268A1 describes a waterborne nail varnish containing film-forming polymer particles that include associative polyurethane as a thickener. This is again useful in cosmetics. Here, associative polyurethane (0.5 to 5 %) comprises hydrophilic polyoxyethylenated sequence. The film forming polymer comprises radical polymers (1 to 50 %) such as vinyl polymers. This vinyl polymer is produced by polymerization of monomers such as a, ß-ethylenic unsaturated carboxylic acids, esters of these acids, amides of said acids, vinyl esters, styrenic monomers. Also, this semi glossy cosmetic composition is consisting of plasticizers, coalescers, dyes, pigments, pearlescent agents, lacquers, anti-UV agents, preservatives, surfactants, spreading agents, perfumes, moisturizing agents.

US5676935A describes a nail varnish based on epoxidized oil as plasticizer for cosmetic applications. This invention describes a nail varnish comprising a film-forming material (15-35 %) such as nitrocellulose, nitrocellulose combined with toluene sulphonamide-formaldehyde resin or an alkyd resin, epoxidized oil as plasticizer such as vernonia oil, pigment (0.1-2.5 %) and one solvent (50-82%) such as mixture of butyl acetate and ethyl acetate. As plasticizer (3-15%), dibutyl phthalate, tributyl acetylcitrate, neopentyl glycol ester, propylene glycol ester, glyceryl benzoate, and camphor.

There is a need in the art to provide coatings that can be applied easily on metallic substrates like bolts, nails, threaded parts of galvanized iron (GI) pipes, GI and galvalume sheets to provide effective corrosion resistance during transportation and storage of these substrates. The present application attempts to address this need.

STATEMENT OF THE DISCLOSURE
The present disclosure relates to a coating composition comprising: a) Component A, comprising an aliphatic polyurethane resin and an epoxy silane modified epoxidized linseed oil, and b) Component B, comprising a cross-linking agent selected from an aliphatic polyisocyanate based on hexamethylene diisocyanate (PHDI) or a methylated high imino melamine crosslinker (MIMC).

In some embodiments, the coating compositions of the present disclosure comprise an additional agent selected selected from the group consisting of: a surfactant, a rheological modifier, a viscosity reducing agent, demineralized water, a coalescing agent, a wetting agent, a corrosion inhibitor, a water resistance agent, an adhesion promoter, and a combination thereof.

The present disclosure relates to a method for preparing a coating composition, comprising preparing Component A, comprising mixing the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil; and adding Component B to the Component A to obtain the coating composition.

The present disclosure also relates to a method for preparing a metal substrate comprising a) preparing a coating composition, comprising preparing Component A and adding Component B to the Component A in an amount of about 4-5% by weight of the Component A; b) applying the coating composition to the metal substrate; and c) curing the coating composition at room temperature for about 30-45 minutes if PHDI is used as the Component B or at about 80? for about 5-10 minutes if MIMC is used as the Component B.

The present disclosure also relates to metal substrates comprising a coating composition comprising: a) Component A, comprising an aliphatic polyurethane resin and an epoxy silane modified epoxidized linseed oil, and b) Component B, comprising a cross-linking agent selected from PHDI or MIMC.

The present disclosure also relates to use of coating compositions comprising Component A and Component B for coating metal substrates to reduce or prevent corrosion.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1A shows an exemplary chemical structure for an aliphatic polyurethane dispersion employed in the coating compositions of the present disclosure.

Figure 1B shows an exemplary chemical structure for an epoxy silane modified linseed oil employed in the coating compositions of the present disclosure.

Figure 2 shows Tafel plots of coatings obtained from the coating compositions of Examples 1 and 2.

Figure 3 shows bode plots from electro impedance spectroscopic (EIS) analysis of coatings obtained from the coating compositions of Examples 1 and 2.

DETAILED DESCRIPTION OF THE DISCLOSURE
With respect to the use of any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results. Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising” or “containing” or “has” or “having” wherever used, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Reference throughout this specification to “one embodiment” or “an embodiment” or “some embodiments” means that a particular feature, structure or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” or “some embodiments” in various places throughout this specification may not necessarily all refer to the same embodiment. It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combinations.

The term “about” as used herein encompasses variations of +/-10% and more preferably +/-5%, as such variations are appropriate for practicing the present invention.

The present disclosure provides two component coating compositions comprising: Component A comprising an aliphatic polyurethane resin and an epoxy silane modified epoxidized linseed oil and Component B comprising a cross-linking agent selected from an aliphatic polyisocyanate based on hexamethylene diisocyanate (PHDI) or a methylated high imino melamine crosslinker (MIMC). The coating compositions of the present disclosure are water-based coatings, i.e., the solvent employed in preparing the coating compositions is water. The weight percentages for water are discussed in detail in later parts of the application.

In the two component coating compositions of the present disclosure, Component A is considered 100% and Component B is taken according to Component A. For example, in one embodiment, if Component B is present in an amount of 4% by weight of Component A, it is meant that 4 g of Component B is added to 100 g of Component A.

The aliphatic polyurethane resin of the Component A forms the coating or film on metallic substrates. In some embodiments, the aliphatic polyurethane resin employed in the compositions of the present disclosure has formula I: (C9H11O10N4R2)n(R1)2n, where R1 is -C11H15, R2 is -C9H22N+, and n is 5-20, and the number average molecular weight (Mn) of the resin is > 1,000 Dalton. In some embodiments, n ranges from 5-20, 5-18, 5-15, 5-14, 8-20, 8-18, 8-16, 10-20, 10-18, 10-15, 12-20, 12-18, including values and ranges therebetween. In some embodiments, n is 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. In some embodiments, the aliphatic polyurethane resin has a predominantly linear or unbranched structure. In some embodiments, the aliphatic polyurethane resin has a branched structure. A chemical structure of an exemplary aliphatic polyurethane resin is shown in Figure 1A. In an exemplary embodiment, the aliphatic polyurethane resin shown in Figure 1A has the following R1 and R2 groups:

In some embodiments, the epoxy silane modified epoxidized linseed oil employed in the compositions of the present disclosure has formula II: (C57O13H97)3n’[(C6H11O2)SiO2-]n’, where n’ is 1-7. In some embodiments, n’ is 1, 2, 3, 4, 5, 6, or 7. In some embodiments, about 0.5 to 2 g/mol of epoxy silanes occupy about 10-15 g/ml of epoxidized linseed oil. In some embodiments, about 1 g/mol of epoxy silane groups occupy about 13 g/mol of epoxidized linseed oil. The epoxy silane modified epoxidized linseed oil provides additional oxidative crosslinking during curing of the coating composition and improves flexibility of the coating.

A chemical structure of an exemplary epoxy silane modified epoxidized linseed oil where n’ is 6 is shown in Figure 1B. The formula for the epoxy silane modified epoxidized linseed oil shown in Figure 1B is (C57O13H97)18[(C6H11O2)SiO2]6 – (Formula III).

The amount of the aliphatic polyurethane resin ranges from about 25 to 66% by weight of the Component A, including values and ranges therebetween. In some embodiments, the amount of the aliphatic polyurethane resin ranges from about 25 to 66%, about 25 to 63%, about 25 to 60%, about 25 to 57%, about 25 to 55%, about 25 to 53%, about 25 to 50%, about 25 to 45%, about 25 to 40%, about 30 to 66%, about 30 to 63%, about 30 to 60%, about 30 to 55%, about 30 to 50%, about 30 to 45%, about 35 to 66%, about 35 to 63%, about 35 to 60%, about 35 to 55%, about 35 to 50%, about 40 to 66%, about 40 to 63%, about 40 to 60%, about 40 to 55%, about 45 to 66%, including values and ranges therebetween, by weight of the Component A.

The amount of the epoxy silane modified epoxidized linseed oil ranges from about 5 to 11% by weight of the Component A, including values and ranges therebetween. In some embodiments, the amount of the epoxy silane modified epoxidized linseed oil ranges from about 5 to 8%, about 6 to 10%, about 7 to 11%, or about 8 to 11% by weight of the Component A, including values and ranges therebetween.

In some embodiments, the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil are present in the Component A at a ratio of about 5:1 to about 6:1, including values therebetween. For example, in some embodiments, the ratio of the aliphatic polyurethane resin to the epoxy silane modified epoxidized linseed oil in the composition is about 5:1, 5.1:1, 5.2:1, 5.25:1, 5.3:1, 5.4:1, 5.5:1, 5.6:1, 5.7:1, 5:75:1, 5.8:1, 5.9:1, or 6:1, including values therebetween. It would be clear to one of ordinary skill in the art that fractional values falling within the range but not explicitly disclosed here are also encompassed by the present disclosure.

In some embodiments, the Component A comprises one or more additional agents selected from the group consisting of: a surfactant, a rheological modifier, a viscosity reducing agent, demineralized water, a coalescing agent, a wetting agent, a corrosion inhibitor, a water resistance agent, an adhesion promoter, and a combination thereof. That is, in some embodiments, the Component A comprises the aliphatic polyurethane resin, the epoxy silane modified epoxidized linseed oil, and an additional agent listed above, or any combination of the additional agents listed above.

In some embodiments, the Component A comprises a surfactant to dissolve the epoxy silane modified epoxidized linseed oil in demineralized water. In some embodiments, the surfactant is present in an amount of about 0.1-0.3% by weight, including values therebetween. In some embodiments, the surfactant is present in an amount of about 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, or 0.3% by weight of the Component A. In some embodiments, the surfactant is selected from the group consisting of: Bis(2-ethylhexyl)sulfosuccinate sodium salt, docusate potassium salt, and a combination thereof.

In some embodiments, the component A comprises a rheological modifier in an amount of about 0.1-0.5% by weight, including values and ranges therebetween. In some embodiments, a rheological modifier is present in an amount of about 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, or 0.5% by weight of the Component A. In some embodiments, a rheological modifier is present in an amount of about 0.1-0.3%, 0.1-0.4%, 0.2-0.4%, 0.2-0.5% by weight of the component A.

In some embodiments, the rheological modifier is selected from the group consisting of alkylphenol ethoxylate free pure associative polyurethane thickener, hydrophobically modified cellulose ethers, and a combination thereof. In some embodiments, an alkylphenol ethoxylate free pure associative polyurethane thickener having a molecular weight of approximately 104 g/mol or a hydrophobically modified cellulose ether having a molecular weight of approximately 106 g/mol is used as a rheological modifier.

The Component A comprises demineralized water as a solvent. In some embodiments, demineralized water is present in an amount of about 15-40% by weight of the Component A, including values and ranges therebetween. In some embodiments, the Component A comprises demineralized water in an amount of about 15-40%, 15-35%, 15-30%, 15-25%, 20-40%, 20-35%, 20-30%, 25-40%, 25-35%, or 30-40% by weight, including values and ranges therebetween. In some embodiments, the Component A comprises demineralized water in an amount of about 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40% by weight.

In some embodiments, the Component A comprises a viscosity reducing agent in an amount of about 2-5% by weight, including values and ranges therebetween. In some embodiments, the viscosity reducing agent is present in an amount of 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5% by weight of the Component A. In some embodiments, the viscosity reducing agent is present in an amount of about 2-4% or 3-5% by weight of the Component A.

In some embodiments, the viscosity reducing agent is a glycidyl ether of a fatty alcohol. In some embodiments, the glycidyl ether of a fatty alcohol that is employed as a viscosity reducing agent in the present compositions is selected from the group consisting of: lauryl glycidyl ether, stearyl glycidyl ether, oleyl glycidyl ether, cetyl glycidyl ether, and a combination thereof. Any of these viscosity reducing agents can be present in any of the amounts described above.

In some embodiments, the Component A comprises a coalescing agent to lower the minimum temperature for film formation. In some embodiments, the coalescing agent is present in an amount of about 4-10% by weight of the Component A, including values and ranges therebetween. In some embodiments, the coalescing agent is present in an amount of about 4-8%, 4-6%, 5-10%, 5-8%, 6-10%, 7-10%, or 8-10% by weight of the Component A, including values and ranges therebetween. In some embodiments, the coalescing agent is present in an amount of about 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10% by weight of the Component A. In some embodiments, the coalescing agent is selected from the group consisting of butyl cellosolve, diethylene glycol mono-n-butyl ether, and a combination thereof. Any of these coalescing agents can be present in any of the amounts described above.

In some embodiments, the Component A comprises a wetting agent in an amount of about 0.3-1% by weight, including values and ranges therebetween. In some embodiments, the wetting agent is present in an amount of about 0.3-1%, 0.3-0.8%, 0.3-0.6%, 0.3-0.5%, 0.4-1%, 0.4-0.8%, 0.4-0.6%, 0.5-1%, 0.5-0.8%, 0.6-1%, 0.6-0.8%, or 0.7-1% by weight of the Component A, including values and ranges therebetween. In some embodiments, the wetting agent is present in an amount of about 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1% by weight of the Component A. In some embodiments, the wetting agent is selected from the group consisting of a polyether modified polysiloxane, a siloxane based gemini surfactant, and a combination thereof. Any of these wetting agents can be present in any of the amounts described above.

In some embodiments, the Component A comprises an adhesion promoter in an amount of about 0.5-2% by weight, including values and ranges therebetween. In some embodiments, the adhesion promoter is present in an amount of about 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2% by weight of the Component A. In some embodiments, the adhesion promoter is present in an amount of about 0.5-1%, 0.5-1.5%, or 1-2% by weight of the Component A.

In some embodiments, the adhesion promoter is glycidyl propyl trimethoxy silane (GPTMS) or a combination of GPTMS and triethylamine. In some embodiments, the adhesion promoter is a combination of GPTMS and triethylamine, wherein the GPTMS and triethylamine are present at a ratio of about 5:1.

In some embodiments, the Component A comprises a corrosion inhibitor in an amount of about 3-10% by weight, including values and ranges therebetween. In some embodiments, the corrosion inhibitor is present in an amount of about 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10% by weight of the Component A, including values and ranges therebetween. In some embodiments, the corrosion inhibitor is present in an amount of about 3-10%, 3-9%, 3-8%, 3-7%, 3-6%, 3-5%, 4-10%, 4-9%, 4-8%, 4-7%, 4-6%, 5-10%, 5-9%, 5-8%, 5-7%, 6-10%, 6-9%, 6-8%, or 7-10% by weight of the Component A, including values and ranges therebetween.

In some embodiments, the corrosion inhibitor is selected from the group consisting of a water-free sol gel inhibitor, a calcium phosphate-based inhibitor, and a combination thereof. In some embodiments, the corrosion inhibitor is a combination of a calcium phosphate-based inhibitor and a water-free sol gel inhibitor mixed in a ratio of about 3:2.

In some embodiments, the Component A comprises a water resistance agent in an amount of about 0.5-5% by weight, including values and ranges therebetween. In some embodiments, the water resistance agent is present in an amount of about 0.5-5%, 0.5-4.5%, 0.5-4%, 0.5-3.5%, 0.5-3%, 0.5-2.5%, 1-5%, 1-4.5%, 1-4%, 1-3%, 1.5-5%, 1.5-4.5%, 1.5-4%, 1.5-3.5%, 1.5-3%, 2-5%, 2-4.5%, 2-4%, 2.5-5%, 2.5-4.5%, 2.5-4%, 3-5%, or 3-4.5% by weight of the Component A. In some embodiments, the water resistance agent is present in an amount of about 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5% by weight of the Component A. In some embodiments, the water resistance agent is a polyether modified hydroxy-functional polydimethylsiloxane.

In some embodiments, the Component A comprises the aliphatic polyurethane resin, the epoxy silane modified epoxidized linseed oil, and an additional agent selected from the group consisting of: a) a surfactant in an amount of about 0.1-0.3% by weight; b) a rheological modifier in an amount of about 0.1-0.5% by weight; c) demineralized water in an amount of about 15-40% by weight; d) a viscosity reducing agent in an amount of about 2-5% by weight; e) a coalescing agent in an amount of about 4-10% by weight; f) a wetting agent in an amount of about 0.3-1% by weight; g) an adhesion promoter in an amount of about 0.5-2% by weight; h) a corrosion inhibitor in an amount of about 3-10% by weight; i) a water resistance agent in an amount of about 0.5-5% by weight; and j) any combination thereof.

In some embodiments, the Component A comprises the aliphatic polyurethane resin, the epoxy silane modified epoxidized linseed oil, and an additional agent selected from the group consisting of: a) a surfactant, selected from the group consisting of Bis (2-ethylhexyl)sulfosuccinte sodium salt, docusate potassium salt, and a combination thereof, in an amount of about 0.1-0.3% by weight; b) a rheological modifier, selected from the group consisting of alkylphenol ethoxylate free pure associative polyurethane thickener, hydrophobically modified cellulose ethers, and a combination thereof, in an amount of about 0.1-0.5% by weight; c) demineralized water in an amount of about 15-40% by weight; d) a viscosity reducing agent, selected from the group consisting of lauryl glycidyl ether, stearyl glycidyl ether, oleyl glycidyl ether, cetyl glycidyl ether, and a combination thereof, in an amount of about 2-5% by weight; e) a coalescing agent, selected from the group consisting of butyl cellosolve, diethylene glycol mono-n-butyl ether, and a combination thereof, in an amount of about 4-10% by weight; f) a wetting agent, selected from the group consisting of a polyether modified polysiloxane, a siloxane based gemini surfactant, and a combination thereof, in an amount of about 0.3-1% by weight; g) an adhesion promoter, selected from GPTMS or a combination of GPTMS and triethylamine, in an amount of about 0.5-2% by weight; h) a corrosion inhibitor, selected from the group consisting of a water-free sol gel inhibitor, a calcium phosphate-based inhibitor, and a combination thereof, in an amount of about 3-10% by weight; i) a polyether modified hydroxy-functional polydimethylsiloxane as a water resistance agent in an amount of about 0.5-5% by weight; and j) any combination of these additional agents.

An exemplary formulation for the Component A is shown in Table 1 below:
Table 1: Component A formulation
S.N. Ingredients Range (wt.%) Use
1 Aliphatic polyurethane dispersion 25-66 Film formation
2 Epoxy silane modified epoxidized linseed oil 5-11 Excellent intermolecular crosslinking during drying process and improves flexibility
3 Bis (2-ethylhexyl)sulfosuccinate sodium salt 0.1-0.3 Surfactant for dissolving epoxy silane modified epoxidized linseed oil in DM water
4 Alkylphenol ethoxylate free pure associative polyurethane thickener/ hydrophobically modified cellulose ethers 0.1-0.5 Rheological modifier
5 Butyl cellosolve/ diethylene glycol mono-n-butyl ether 4-10 Coalescing agent
6 Demineralized water 15-40 Solvent, medium for hydrolysis and lowering the viscosity of the solution
7 Glycidyl ether of fatty alcohol [lauryl glycidyl ether/stearyl glycidyl ether or oleyl glycidyl ether/lauryl gycidyl ether:steryl glycidyl ether (1:1)] 2-5 Viscosity reducing agents
8 Polyether modified polysiloxane/siloxane based gemini surfactant 0.3-1 Wetting agent /anticrater additive
9 Water-free sol gel inhibitor/calcium phosphate-based inhibitor: water-free sol gel inhibitor (3:2) 3-10 Corrosion inhibitor
10 Polyether modified hydroxy-functional polydimethylsiloxane 0.5 -5 Water resistance
11 Glycidyl propyl trimethoxy silane/ Glycidyl propyl trimethoxysilane :Triethylamine (5:1) 0.5-2 Adhesion promotor

The coating compositions of the present disclosure comprise two components: Component A and Component B. The Component A is described in detail above. The Component B comprises a cross-linking agent and is added to the Component A just prior to applying the coating composition to metallic substrates. In some embodiments, the Component B comprises a cross-linking agent selected from an aliphatic polyisocyanate based on hexamethylene diisocyanate (PHDI) or a methylated high imino melamine crosslinker (MIMC).

The term “aliphatic polyisocyanate based on hexamethylene diisocyanate” or “PHDI” refers to a polymer comprising “n” number of monomers of an isocyanate comprising hexamethylene diisocyanate. In some embodiments, n can range from 1-4.

The term “methylated high imino melamine crosslinker” or “MIMC” refers to a methylated melamine crosslinker resin containing imino groups. In some embodiments, the degree of methylation in MIMC is 3.

In some embodiments, the Component B is present in the composition in an amount of about 4-5% by weight of the Component A. In some embodiments, the Component B is present in the composition in an amount of about 4, 4.25, 4.5, 4.75, or 5%, including values therebetween, by weight of the Component A. As discussed above, if Component B is present in an amount of 4% by weight of Component A, it is meant that 4 g of Component B is added to 100 g of Component A.

The present disclosure also provides a method for preparing the coating composition, comprising: preparing the Component A comprising mixing the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil; and adding the Component B to the Component A to obtain the coating composition.

The formulas for the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil are as described above. In some embodiments, the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil are mixed at a ratio of from about 5:1 to about 6:1, including values therebetween. In some embodiments, the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil are mixed at a ratio of about 5:1, 5.1:1, 5.2:1, 5.25:1, 5.3:1, 5.4:1, 5.5:1, 5.6:1, 5.7:1, 5:75:1, 5.8:1, 5.9:1, or 6:1, including values therebetween. It would be clear to one of ordinary skill in the art that fractional values falling within the range but not explicitly disclosed here are also encompassed by the present disclosure.

In some embodiments, about 25-66% by weight of the aliphatic polyurethane resin is mixed with about 5-11% by weight of the epoxy silane modified epoxidized linseed oil.

In some embodiments, about 25 to 66%, about 25 to 63%, about 25 to 60%, about 25 to 57%, about 25 to 55%, about 25 to 53%, about 25 to 50%, about 25 to 45%, about 25 to 40%, about 30 to 66%, about 30 to 63%, about 30 to 60%, about 30 to 55%, about 30 to 50%, about 30 to 45%, about 35 to 66%, about 35 to 63%, about 35 to 60%, about 35 to 55%, about 35 to 50%, about 40 to 66%, about 40 to 63%, about 40 to 60%, about 40 to 55%, or about 45 to 66%, including values and ranges therebetween, of the aliphatic polyurethane resin is mixed with about 5 to 11%, about 5 to 8%, about 6 to 10%, about 7 to 11%, or about 8 to 11%, including values and ranges therebetween, of the epoxy silane modified epoxidized linseed oil keeping the ratio of the resin to the oil about 5:1 to 6:1.

In some embodiments, the step of preparing the Component A comprises adding a surfactant to the dispersion comprising the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil. The weight range for the surfactant and exemplary surfactants are described above.

In some embodiments, the aliphatic polyurethane resin, the epoxy silane modified epoxidized linseed oil, and the surfactant are added to a reaction vessel and this dispersion is stirred at about 45-55? for about 30 minutes followed by providing nitrogen for about 1 hour with stirring and heating the mixture at about 80? for about 15 minutes. In these embodiments, stirring at about 45-55? for about 30 minutes includes stirring at a temperature of about 45?, 46?, 47?, 48?, 49?, 50?, 51?, 52?, 53?, 54?, or 55? for about 30 minutes.

In some embodiments, the step of preparing the Component A further comprises adding to the dispersion comprising the aliphatic polyurethane resin, the epoxy silane modified epoxidized linseed oil, and the surfactant, an additional agent selected from the group consisting of: a rheological modifier, a viscosity reducing agent, demineralized water, a coalescing agent, a wetting agent, a corrosion inhibitor, a water resistance agent, an adhesion promoter, and a combination thereof.

In some embodiments, after heating the dispersion comprising the aliphatic polyurethane resin, the epoxy silane modified epoxidized linseed oil, and the surfactant to about 80?, a rheological modifier, a coalescing agent and demineralized water are added to the dispersion and the dispersion is heated up to 50? to facilitate cross-linking with the rheological modifier and the coalescing agent. The weight ranges for the rheological modifier, the coalescing agent and demineralized water are described above. Exemplary rheological modifiers and coalescing agents are described above.

In some embodiments, an alkylphenol ethoxylate free pure associative polyurethane thickener having a molecular weight of approximately 104 g/mol or a hydrophobically modified cellulose ether having a molecular weight of approximately 106 g/mol is used as a rheological modifier. Both rheological modifiers exhibit less spatter when the coating composition is applied using a roller or brush. If an alkylphenol ethoxylate free pure associative polyurethane thickener is used as a rheological modifier, it is first diluted with demineralized water to prevent coagulation of the dispersion. If a hydrophobically modified cellulose ether is used as a rheological modifier, it does not require any dilution prior to mixing with the dispersion.

With the addition of demineralized water, the dispersion changes into a solution. The solution is stirred for up to 10-15 minutes at about 1500 rpm. In some embodiments, to reduce the viscosity of the solution, a viscosity reducing agent is added. In some embodiments, a wetting agent and an adhesion promoter are added to the solution. The weight ranges for the viscosity reducing agent, the wetting agent, and the adhesion promoter are described above. Exemplary viscosity reducing agents, wetting agents and adhesion promoters are described above. After addition of the viscosity reducing agent, the wetting agent, and the adhesion promoter, the solution is stirred for about one hour at about 600 rpm. In some embodiments, a corrosion inhibitor and a water resistance agent are added to the solution and the solution is stirred for about 30 minutes at slow speed, e.g., about 220-250 rpm.

In some embodiments, a method for preparing the Component A comprises: preparing the Component A comprising mixing the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil; and adding the Component B to the Component A to obtain the coating composition.

In some embodiments, the step of preparing the Component A comprises: a) mixing the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil to obtain a dispersion; b) adding a surfactant to the dispersion of step a), stirring the dispersion at about 45-55? for about 30 minutes followed by providing nitrogen for about 1 hour with stirring and heating the dispersion at about 80?; c) adding a rheological modifier, a coalescing agent, and demineralized water to the dispersion and heating and stirring the dispersion to obtain a solution; d) adding a viscosity reducing agent, a wetting agent, and an adhesion promoter to the solution and stirring the solution; e) adding a corrosion inhibitor and a water resistance agent and stirring the solution to provide the Component A. The surfactant, the rheological modifier, the viscosity reducing agent, the coalescing agent, the wetting agent, the corrosion inhibitor, the water resistance agent, and the adhesion promoter are as described above. In some embodiments, addition of a wetting agent, an adhesion promoter, a corrosion inhibitor, and a water resistance agent is optional; i.e., all four of these agents are added or some of these agents are added or none of these agents are added.

In some embodiments, the step of preparing the Component A comprises: a) mixing about 25-66% by weight of the aliphatic polyurethane resin with about 5-11% by weight of the epoxy silane modified epoxidized linseed oil to obtain a dispersion; b) adding about 0.1-0.3% by weight of a surfactant to the dispersion of step a), stirring the dispersion at about 45-55? for about 30 minutes followed by providing nitrogen for about 1 hour with stirring and heating the dispersion at about 80? for about 15 minutes; c) adding about 0.1-0.5% by weight of a rheological modifier, about 4-10% by weight of a coalescing agent, and about 15-40% by weight of demineralized water to the dispersion, heating the dispersion to about 50? and stirring the dispersion for up to 15 minutes at about 1500 rpm to obtain a solution; d) adding about 2-5% by weight of a viscosity reducing agent, about 0.3-1% by weight of a wetting agent, and about 0.5-2% by weight of an adhesion promoter to the solution and stirring the solution for about an hour at about 600 rpm; e) adding about 3-10% by weight of a corrosion inhibitor and about 0.5-5% by weight of a water resistance agent and stirring the solution for about 30 minutes at about 200-250 rpm to provide the Component A. The surfactant, the rheological modifier, the viscosity reducing agent, the coalescing agent, the wetting agent, the corrosion inhibitor, the water resistance agent, and the adhesion promoter are as described above. In some embodiments, addition of a wetting agent, an adhesion promoter, a corrosion inhibitor, and a water resistance agent is optional; i.e., all four of these agents are added or some of these agents are added or none of these agents are added.

The above steps describe how the Component A is prepared. To prepare the coating composition, the Component B is added to the Component A in an amount of about 4-5% by weight of the Component A.

The Component B comprises a cross-linking agent. In some embodiments, the cross-linking agent is an aliphatic polyisocyanate based on hexamethylene diisocyanate (PHDI) or a methylated high imino melamine crosslinker (MIMC). To prepare the coating composition, the Component B is added to the Component A just prior to application of the coating composition to metallic substrates. In some embodiments, the Component B is added to the Component A about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 minutes minutes prior to application of the coating composition to a substrate. If MIMC is employed as Component B, it is diluted with polyethylene glycol before mixing with the Component A.

The coating composition comprising the Component A and the Component B is used for coating metallic substrates to provide corrosion resistance. Accordingly, the present disclosure provides use of the coating compositions described herein for reducing or preventing corrosion of metallic substrates.

The present disclosure also provides a method for preparing a metal substrate comprising the coating composition disclosed herein. The method comprises: a) preparing the coating composition; b) applying the coating composition to the metal substrate; and c) curing the coating composition at room temperature for about 30-45 minutes if PHDI is used as the Component B or at about 80? for about 5-10 minutes if MIMC is used as the Component B. The step of preparing the coating composition comprises preparing the Component A and adding the Component B to the Component A in an amount of about 4-5% by weight of the Component A. This is described in greater details above. In some embodiments, the coating composition is applied to metallic substrates by dip coating, roller coating or brush coating. After applying the coating composition to a metallic substrate, the coating composition is cured. The conditions for curing depend on the Component B of the composition.

When PHDI is used as the Component B, the composition applied to the metal substrate is cured at room temperature for about 30-45 minutes. The term “room temperature” as used herein refers to temperatures ranging from about 10? to 50?, including values and range therebetween. In some embodiments, the room temperature is about 10? to 45?, 10? to 40?, 10? to 35?, 10? to 30?, 15? to 50?, 15? to 45?, 15? to 40?, 15? to 30?, 15? to 25?, 20? to 50?, 20? to 45?, 20? to 40?, 20? to 35?, 20? to 30?, 25? to 50?, 25? to 45?, 25? to 40?, 25? to 35?, 25? to 30?, 30? to 50?, 30? to 45?, or 30? to 40?, including values and ranges therebetween. In some embodiments, the room temperature is about 15? to 45?, 20? to 45?, 20? to 40?, 25? to 45?, 25? to 40?, or 25? to 35?.

When MIMC is used as the Component B, the composition applied to the metal substrate is cured at about 80? for about 5-10 minutes.

The coating compositions of the present disclosure are applied to metal substrates such as bolts, nails, threaded parts of galvanized iron pipes, galvanized iron sheets and galvalume sheets. In some embodiments, bolts and nails are iron bolts and iron nails.

The present disclosure also provides metal substrates prepared by the method described above.

The present disclosure also provides metal substrates comprising the coating compositions described herein.

The coating compositions of the present disclosure, when applied to metal substrates, show one or more of the following properties:
Specific gravity (as measured by ASTM D 891-09): 0.95 -1.05
Thickness of dry films (as measured by ASTM E 376-11): 1 – 10 µ in one-time application.
Cross hatch adhesion test (as measured by ASTM D 3359 -09): 5B (No removal of coating)
Appearance (as measured by ASTM D 523-14): Satin finish (with PHDI as Component B) or Glossy finish (when polyethylene glycol diluted MIMC used as Component B)

The coating compositions of the present disclosure form a clear thin laminating coating on metal substrates. The present coating compositions exhibit fast drying upon applying to metal substrates. Coatings obtained from these compositions show good flexibility and excellent mechanical and chemical resistance. The coating compositions of the present disclosure are particularly useful for construction applications where temporary protection in required during storage and transportation such as that required for bolts, nails (fasten pieces of wood together, used in plastic, drywall, masonry, and concrete), threaded parts of galvanized iron pipes (plumbing application), galvalume and galvanized iron sheets.

It is to be understood that the foregoing descriptive matter is illustrative of the disclosure and not a limitation. While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. Those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. Similarly, additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based upon description provided herein.

Descriptions of well-known/conventional methods/steps and techniques are omitted so as to not unnecessarily obscure the embodiments herein. Further, the disclosure herein provides for examples illustrating the above described embodiments, and in order to illustrate the embodiments of the present disclosure certain aspects have been employed. The examples used herein for such illustration are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the following examples should not be construed as limiting the scope of the embodiments herein.

EXAMPLES

Example 1: Coating Composition
The Component A was prepared as follows: To prepare Component A, an aliphatic polyurethane dispersion having the formula (I) - (C9H11O10N4R2)n(R1)2n, where R1 is -C11H15, R2 is -C9H22N+, and n is 6 and epoxy silane modified epoxidized linseed oil having the formula (C57O13H97)3n’[(C6H11O2)SiO2-]n’, where n’ is 3 were used. 50 wt.% of aliphatic polyurethane dispersion was mixed with 10 wt.% of epoxy silane modified epoxidized linseed oil in 5:1 ratio (1 g/mol of epoxy silane occupied 13 g/mol of epoxidized linseed oil with free -OH functional groups to further react with other molecules and substrate). To solubilize the epoxidized linseed oil in demineralized water, 0.1 wt.% of bis(2-ethylhexyl) sulfosuccinate sodium salt was added as a surfactant to the above dispersion. The dispersion was stirred at 600 rpm on a magnetic stirrer at 50? for half an hour in a reaction vessel by providing nitrogen for 1 an hour with stirring followed by heating at 80? for 15 minutes. This solution was kept for 15 minutes to be cooled down. To this dispersion, 0.4 wt. % of hydrophobically modified cellulose ethers having a molecular weight of 106 g/mol (rheological modifier), 5 wt. % of butyl cellosolve (coalescing agent) and 25.9 wt.% of demineralized water were added and the dispersion was heated up to 50? to get crosslinking with these agents. The hydrophobically modified cellulose ethers do not require any dilution prior to mixing with the dispersion.. This solution was stirred up to 15 minutes at 1500 rpm. The consistency of the solution became thick; therefore, to reduce its viscosity, 2 wt.% of lauryl glycidyl ether was added as a viscosity reducing agent. To increase the wettability and adherence of the coating solution over a substrate, 0.5 wt. % of polyether modified polysiloxane and 0.6 wt. % of glycidyl propyl trimethoxy silane:triethylamine (0.5:0.1) were added to the solution. The solution was mixed for one hour at 600 rpm. To inhibit the corrosion reaction on a metal substrate, 3 wt. % of water-free sol gel inhibitor was added as a corrosion inhibitor and 2 wt.% of polyether modified hydroxy-functional polydimethylsiloxane was added as a water resistance agent. The addition of these agents increases the hydrophobicity, oleophobicity, dust repellence and water resistance of the coating films obtained from this coating composition. The above solution was stirred for half an hour at slow speed (240 rpm) to obtain the Component A.

To the Component A prepared above, PHDI was added as the Component B to obtain the coating composition. The coating composition was immediately applied to iron nails and the applied coating was allowed to dry at room temperature. The coating composition dried within 30 minutes.

To the Component A prepared above, MIMC diluted with polyethylene glycol was added as the Component B to obtain the coating composition. The coating composition was immediately applied to iron nails and the applied coating was cured at 80? for 5 minutes.

Example 2: Coating Composition
The Component A was prepared as follows: 60 wt.% of aliphatic polyurethane dispersion was mixed with 10 wt.% of epoxy silane modified epoxidized linseed oil in 6:1 ratio (1 g/mol of epoxy silane occupied 13 g/mol of epoxidized linseed oil with free -OH functional groups to further react with other molecules and substrate). To solubilize the epoxidized linseed oil in demineralized water, 0.1 wt.% of bis(2-ethylhexyl) sulfosuccinate sodium salt was added as a surfactant to the above dispersion. The dispersion was stirred at 600 rpm on a magnetic stirrer at 50? for half an hour in a reaction vessel by providing nitrogen for an hour with stirring and heating at 80? for 15 minutes. This solution was kept for 15 minutes to be cooled down. To this dispersion, 0.4 wt. % of alkylphenol ethoxylate free polyurethane thickener having a molecular weight of approximately 104 g/mol (rheological modifier), 4 wt. % of diethylene glycol mono-n-butyl ether having a molecular weight of approximately 106 g/mol (coalescing agent), and 24.6 wt.% of demineralized water were added and the dispersion was heated up to 50? to get crosslinking with these agents. The alkylphenol ethoxylate free polyurethane thickener was diluted with demineralized water prior to mixing with the dispersion to prevent coagulation of the dispersion. The solution was stirred up to 15 minutes at 1500 rpm. The consistency of the solution became thick; therefore, to reduce its viscosity, 2 wt.% of lauryl glycidyl ether with steryl glycidyl ether in 1:1 ratio were added as viscosity reducing agents. To increase the wettability and adherence of the coating solution over a substrate, 1 wt. % of siloxane based gemini surfactant (wetting agent) and 0.5 wt. % of glycidyl propyl trimethoxy silane (adhesion promoter) were added to the solution. The solution was mixed for one an hour at 600 rpm. To inhibit the corrosion reaction on a metal substrate, 5 wt. % of calcium phosphate-based inhibitor with water-free sol gel inhibitor in 3:2 ratio was added as a corrosion inhibitor and 2 wt.% of polyether modified hydroxy-functional polydimethylsiloxane was added as a water resistance agent. This helps in increasing the hydrophobicity, oleophobicity, dust repellancy and water resistance. The addition of these agents increases the hydrophobicity, oleophobicity, dust repellence and water resistance of the coating films obtained from this coating composition. The above solution was stirred for half an hour at slow speed (240 rpm) to obtain the Component A.

To the Component A prepared above, PHDI was added as the Component B to obtain the coating composition. The coating composition was immediately applied to iron nails and the applied coating was allowed to dry at room temperature. The coating composition dried within 30 minutes.

To the Component A prepared above, MIMC diluted with polyethylene glycol was added as the Component B to obtain the coating composition. The coating composition was immediately applied to iron nails and the applied coating was cured at 80? for 10 minutes.

Example 3: Analysis of the coatings obtained from the compositions of Examples 1 and 2
The formulation of the Component A of Examples 1 and 2 is summarized in Table 2 below.

Table 2: Component A of Examples 1 and 2
S.N. Example 1 Example 2
1 50 wt. % of aliphatic polyurethane dispersion: 10 wt. % epoxy silane modified epoxidized linseed oil (5:1) 60 wt. % of aliphatic polyurethane dispersion: 10 wt. % epoxy silane modified epoxidized linseed oil (6:1)
2 0.1 wt.% of bis (2-ethylhexyl) sulfosuccinte sodium salt 0.1 wt. % of bis (2-ethylhexyl) sulfosuccinte sodium salt
3 0.4 wt. % of hydrophobically modified cellulose ethers 0.3 wt. % of alkylphenol ethoxylate free polyurethane thickeners
4 5 wt. % of butyl cellosolve 4 wt. % of diethylene glycol mono-n-butyl ether
5 25.9 wt. % of demineralized water 24.6 wt. % of demineralized water
6 2 wt. % of lauryl glycidyl ether 2 wt. % of lauryl glycidyl ether: steryl glycidyl ether (1:1)
7 0.5 wt. % of polyether modified polysiloxane 1 wt. % of siloxane based gemini surfactant
8 3 wt. % of water-free sol gel inhibitor 5 wt. % of calcium phosphate-based inhibitor: water free sol gel inhibitor (3:2)
9 2 wt.% of polyether modified hydroxy-functional polydimethylsiloxane 2 wt.% of polyether modified hydroxy-functional polydimethylsiloxane
10 0.6 wt. % of glycidyl propyl trimethoxysilane:triethylamine (0.5:0.1) 0.5 wt. % of glycidyl propyl trimethoxysilane

The coatings on iron nails obtained from the compositions of Examples 1 and 2 were examined through polarization tests [Tafel plot and Electro impedance spectroscopy (EIS)] and an environmental test. The results are shown in Table 3, Figure 2 (Tafel plot) and Figure 3 (EIS). The environmental test duration was kept for 100 days in rainy season.

Table 3: Properties of various coatings
Properties Example 1 - PHDI Example 1 - MIMC Example 2 - PHDI Example 2- MIMC
Environmental testing (<5 wt. % red rust in hours) > 2040 > 1920 > 2280 > 2088
Corrosion rate (mpy) 2.087 2.209 1.014 1.89
Ecorr (mv) -772 -644 -866 -752
Zmod (ohm cm2) 2.39 E+03 7.74 E+02 1.51 E+04 2.88E+03
mpy: Mils penetration per year;
mv: milli volt

High corrosion rate indicates lower corrosion resistance and high impedance value (Zmod) indicates higher corrosion resistance.

INCORPORATION BY REFERENCE
All references, articles, publications, patents, patent publications, and patent applications cited herein are incorporated by reference in their entireties for all purposes. However, mention of any reference, article, publication, patent, patent publication, and patent application cited herein is not, and should not be taken as, an acknowledgment or any form of suggestion that they constitute valid prior art or form part of the common general knowledge in any country in the world.

Claims:We Claim:
1. A coating composition comprising:
a. Component A, comprising an aliphatic polyurethane resin and an epoxy silane modified epoxidized linseed oil, and
b. Component B, comprising a cross-linking agent selected from an aliphatic polyisocyanate based on hexamethylene diisocyanate (PHDI) or a methylated high imino melamine crosslinker (MIMC).
2. The coating composition as claimed in claim 1, wherein the aliphatic polyurethane resin has formula I: (C9H11O10N4R2)n(R1)2n, where R1 is -C11H15, R2 is -C9H22N+, and n is 5-20.
3. The coating composition as claimed in claim 1, wherein the epoxy silane modified epoxidized linseed oil has formula II: (C57O13H97)3n’[(C6H11O2)SiO2-]n’, where n’ is 1-7.
4. The coating composition as claimed in claim 1, wherein the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil are present at a ratio of about 5:1 to about 6:1.
5. The coating composition as claimed in claim 1, wherein the aliphatic polyurethane resin is present in an amount of about 25-66% by weight of the Component A and the epoxy silane modified epoxidized linseed oil is present in an amount of about 5-11% by weight of the Component A.
6. The coating composition as claimed in claim 1, wherein the Component A comprises an additional agent selected from the group consisting of: a surfactant, a rheological modifier, a viscosity reducing agent, demineralized water, a coalescing agent, a wetting agent, a corrosion inhibitor, a water resistance agent, an adhesion promoter and a combination thereof.
7. The coating composition as claimed in claim 6, wherein the Component A comprises a surfactant in an amount of about 0.1-0.3% by weight.
8. The coating composition as claimed in claim 0, wherein the surfactant is selected from the group consisting of: Bis (2-ethylhexyl)sulfosuccinate sodium salt, docusate potassium salt and a combination thereof.
9. The coating composition as claimed in claim 6, wherein the Component A comprises a rheological modifier in an amount of about 0.1-0.5% by weight.
10. The coating composition as claimed in claim 9, wherein the rheological modifier is selected from the group consisting of alkylphenol ethoxylate free pure associative polyurethane thickener, hydrophobically modified cellulose ethers and a combination thereof.
11. The coating composition as claimed in claim 6, wherein the Component A comprises demineralized water in an amount of about 15-40% by weight.
12. The coating composition as claimed in claim 6, wherein the Component A comprises a viscosity reducing agent in an amount of about 2-5% by weight.
13. The coating composition as claimed in claim 12, wherein the viscosity reducing agent is a glycidyl ether of fatty alcohol.
14. The coating composition as claimed in claim 13, wherein the viscosity reducing agent is selected from the group consisting of lauryl glycidyl ether, stearyl glycidyl ether, oleyl glycidyl ether, cetyl glycidyl ether and a combination thereof.
15. The coating composition as claimed in claim 6, wherein the Component A comprises a coalescing agent in an amount of about 4-10% by weight.
16. The coating composition as claimed in claim 15, wherein the coalescing agent is selected from the group consisting of butyl cellosolve, diethylene glycol mono-n-butyl ether and combination thereof.
17. The coating composition as claimed in claim 6, wherein the Component A comprises a wetting agent in an amount of about 0.3-1% by weight.
18. The coating composition as claimed in claim 17, wherein the wetting agent is selected from the group consisting of a polyether modified polysiloxane, a siloxane based gemini surfactant and combination thereof.
19. The coating composition as claimed in claim 6, wherein the Component A comprises an adhesion promoter in an amount of about 0.5-2% by weight.
20. The coating composition as claimed in claim 19, wherein the adhesion promoter is glycidyl propyl trimethoxy silane (GPTMS) or a combination of GPTMS and triethylamine.
21. The coating composition as claimed in claim 20, wherein the GPTMS and triethylamine are present at a ratio of about 5:1.
22. The coating composition as claimed in claim 6, wherein the Component A comprises a corrosion inhibitor in an amount of about 3-10% by weight.
23. The coating composition as claimed in claim 22, wherein the corrosion inhibitor is selected from the group consisting of a water-free sol gel inhibitor, a calcium phosphate-based inhibitor and a combination thereof.
24. The coating composition as claimed in claim 23, wherein the calcium phosphate-based inhibitor and the water-free sol gel inhibitor are mixed in a ratio of about 3:2.
25. The coating composition as claimed in claim 6, wherein the Component A comprises a water resistance agent in an amount of about 0.5-5% by weight.
26. The coating composition as claimed in claim 25, wherein the water resistance agent is a polyether modified hydroxy-functional polydimethylsiloxane.
27. The coating composition as claimed in claim 1, wherein the Component B is present in an amount of about 4-5% by weight of the Component A.
28. A method for preparing a coating composition of claim 1, comprising
preparing the Component A, comprising mixing the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil; and
adding the Component B to the Component A to obtain the coating composition.
29. The method as claimed in claim 28, wherein the aliphatic polyurethane resin has formula I: (C9H11O10N4R2)n(R1)2n, where R1 is -C11H15, R2 is -C9H22N+, and n is 5-20.
30. The method as claimed in claim 28, wherein the epoxy silane modified epoxidized linseed oil has formula II: (C57O13H97)3n’[(C6H11O2)SiO2-]n’, where n’ is 1-7.
31. The method as claimed in claim 28, wherein the aliphatic polyurethane resin and the epoxy silane modified epoxidized linseed oil are mixed at a ratio of from about 5:1 to about 6:1.
32. The method as claimed in claim 28, wherein about 25-66% by weight of the aliphatic polyurethane resin is mixed with about 5-11% by weight of the epoxy silane modified epoxidized linseed oil.
33. The method as claimed in claim 28, comprising adding to the Component A an additional agent selected from the group consisting of: a surfactant, a rheological modifier, a viscosity reducing agent, demineralized water, a coalescing agent, a wetting agent, a corrosion inhibitor, a water resistance agent, an adhesion promoter, and a combination thereof
34. The method as claimed in claim 33, comprising adding a surfactant to the Component A in an amount of about 0.1-0.3% by weight by stirring at about 45-55? for about 30 minutes followed by providing nitrogen for about 1 hour with stirring and heating at about 80?.
35. The method as claimed in claim 34, comprising heating the Component A to about 50?; adding to the Component A a rheological modifier in an amount of about 0.1-0.5% by weight, a coalescing agent in an amount of about 4-10% by weight, and demineralized water in an amount of about 15-40% by weight; and stirring the Component A for up to 15 minutes at about 1500 rpm.
36. The method as claimed in claim 34, comprising adding a viscosity reducing agent to the Component A in an amount of about 2-5% by weight.
37. The method as claimed in claim 34, comprising adding to the Component A, a wetting agent in an amount of about 0.3-1% by weight and an adhesion promoter in an amount of about 0.5-2% by weight; and stirring the Component A for about an hour at about 600 rpm.
38. The method as claimed in claim 34, comprising adding to the Component A, a corrosion inhibitor in an amount of about 3-10% by weight and a water resistance agent in an amount of about 0.5-5% by weight; and stirring the Component A for about 30 minutes at about 200-250 rpm.
39. The method as claimed in claim 28, wherein the Component B is added to the Component A in an amount of about 4-5% by weight.
40. The method as claimed in claim 28, wherein the Component B is added to the Component A about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 minutes prior to application of the coating composition to a substrate.
41. A method for preparing a metal substrate comprising the coating composition as claimed in claim 1, said method comprising:
a. preparing the coating composition, comprising preparing the Component A and adding the Component B to the Component A in an amount of about 4-5% by weight of the Component A;
b. applying the coating composition to the metal substrate; and
c. curing the coating composition at room temperature for about 30-45 minutes if PHDI is used as the Component B or at about 80? for about 5-10 minutes if MIMC is used as the Component B.
42. The method as claimed in claim 41, wherein the metal substrate is selected from the group consisting of: bolts, nails, threaded parts of galvanized iron pipes, galvanized iron sheets and galvalume sheets.
43. A metal substrate prepared by the method as claimed in claim 41.
44. A metal substrate comprising the coating composition as claimed in claim 1.