Patent Description:
Protective metal coating which is also referred to as conversion coating is a common practise that involves metal surface treatment to enhance the corrosion resistance. The metalworking fluid (MWF) technology utilizes various phosphates, sulphonates or silicates which primarily function as corrosion inhibitor in the formulations. However, phosphorus or sulfur containing compounds have inherent shortcomings of accumulating excessive nutrients in the aqueous systems causing microbial proliferation. Although silicates do not cause microbial growth, low hydrocarbyl silicates have gelling or precipitation issues due to their tendency to form insoluble three-dimensional networks in the aqueous systems. The phosphate treatments to the metallic surfaces have been applied traditionally to impart corrosion. However, phosphate treatment has a problem of sludge formation as a by-product.

In the state of the art, metal treatment composition and methods are known and described, for instance, in the following references.

<CIT> discloses a chrome free rinse process and solutions for treating metal surfaces such as iron, zinc, steel, aluminum, and alloys thereof by contacting the metal surface with an aqueous composition consisting of a soluble zirconium containing compound.

<CIT>, <CIT> discloses a process to treat steel, aluminum, aluminum alloys, zinc, zinc alloys with an aqueous solution of a flurophosphate salt to passivate the metal surface.

<CIT> discloses a non-chrome post-rinse composition comprising the reaction product of an epoxy-functional material containing at least two epoxy groups, an alkanolamine, or a mixture of alkanolamines for treating phosphate metal substrates.

Aqueous compositions or emulsions comprising a cationic polyurethane polymer and at least one water-soluble metal salt which are used for treating metal substrates to form protective coating thereon are disclosed in <CIT>, <CIT>, <CIT> and <CIT>.

The methods and compositions disclosed in the prior arts have limitations. The compositions described in the prior arts disclose non-chromium pre-treatment that are more sensitive to different intermetallic composition of metal alloys in terms of the performance. The organic oligomers and polymers known in the prior-art to treat intermetallic compositions have limitations with respect to solubility and stability in the final product.

There is a need for an improved metal pre-treatment composition and a method that can overcome the above-mentioned drawbacks.

Hence, it is an object of the presently claimed invention to provide a metal pre-treatment composition that is stable and shows improved performance such as adhesion, T-bend, reverse impact and corrosion resistance on various different substrates such as aluminium and cold rolled sheet.

Surprisingly, it was found that a metal pre-treatment composition comprising aminosalicylic acid-functionalized polyurethane oligomers demonstrated good stability and improved performance such as adhesion, stability, T-bend, reverse impact and corrosion resistance on various different substrates such as aluminium and cold rolled sheet. In addition, aminosalicylic acid- functionalized polyurethane oligomers easily blends into the metal pre-treatment composition and is less sensitive to metal alloy variation and can be used in a multi-metal or metal alloy composition.

Accordingly, in one aspect, the presently claimed invention is directed to a polyurethane polymer which is obtainable by.

In another aspect, the presently claimed invention is directed to an aqueous composition comprising at least one polyurethane polymer described herein and water.

In yet another aspect, the presently claimed invention is directed to a metal pre-treatment composition comprising the aqueous composition described herein and at least one water-soluble metal-salt or metal.

In another aspect, the presently claimed invention is directed to the use of the metal pre-treatment composition described herein for coating a metal substrate.

In yet another aspect, the presently claimed invention is directed to a method for pre-treating a metal substrate comprising at least the step of contacting a metal substrate with the metal pre-treatment composition described herein.

In another aspect, the presently claimed invention is directed to a coated metal substrate obtainable by a method for pre-treating a metal substrate described herein.

The presently claimed invention is associated with at least one of the following advantages:.

Other objects, advantages and applications of the presently claimed invention will become apparent to those skilled in the art from the following detailed description.

<FIG>: FTIR of oligomer A indicated the overlapping of OH O-H Stretch, (broad, s) with Urea N-H stretch <NUM>-<NUM> (M) at wavenumber range (<NUM> to <NUM>).

The following detailed description is merely exemplary in nature and is not intended to limit the presently claimed invention or the application and uses of the presently claimed invention. Furthermore, there is no intention to be bound by any theory presented in the preceding technical field, background, summary or the following detailed description.

Furthermore, the terms "(a)", "(b)", "(c)", "(d)" etc. and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the subject matter described herein are capable of operation in other sequences than described or illustrated herein. In case the terms "(A)", "(B)" and "(C)" or "(a)", "(b)", "(c)", "(d)", "(i)", "(ii)" etc. relate to steps of a method or use or assay there is no time or time interval coherence between the steps, that is, the steps may be carried out simultaneously or there may be time intervals of seconds, minutes, hours, days, weeks, months or even years between such steps, unless otherwise indicated in the application as set forth herein above or below.

Furthermore, the ranges defined throughout the specification include the end values as well, i.e. a range of <NUM> to <NUM> implies that both <NUM> and <NUM> are included in the range. For the avoidance of doubt, the applicant shall be entitled to any equivalents according to applicable law. For the purposes of the presently claimed invention, the term 'aqueous' is defined as a system which comprises a significant fraction of water as the main dispersion medium.

Reference throughout this specification for compound names starting with 'poly' designate substances, which formally contain per molecule, two or more of the functional groups. The compound itself can be monomeric, oligomeric or polymeric compound. For instance, a polyol is a compound having two or more hydroxy groups, a polyisocyanate is a compound having two or more isocyanate groups.

Reference throughout this specification to the term 'prepolymer' refers to a monomer or system of monomers that have been reacted to an intermediate molecular mass state. This material is capable of further polymerization by reactive groups to a fully cured high molecular weight state.

Reference throughout this specification to the term 'oligomer' denotes a molecule that consists of <NUM>-<NUM> monomers but does not necessarily have a molecular mass distribution.

For the purposes of the presently claimed invention, a cation is defined as a positively charged ion and has a natural ability to move toward the negative electrode in electrolysis.

For the purposes of the presently claimed invention, aliphatic isocyanates are defined as isocyanates, in which the NCO group is not directly attached to an aromatic ring.

For the purposes of the presently claimed invention, functional polymers/oligomers or functionalized polymers/oligomers are defined as polymers/oligomers whose properties are determined by the functional groups present in the polymers/oligomers that are dissimilar to the backbone chains.

For the purposes of the presently claimed invention, 'metal pre-treatment' is defined as the treatment of metal surfaces or metal parts before preparing the metal workpiece for end use such as painting.

For the purposes of the presently claimed invention, the term "curing" denotes the heat-initiated crosslinking of a coating film, with either self-crosslinking binders or else a separate crosslinking agent, in combination with a polymer as binder, (external crosslinking), being used in the parent coating material.

For the purposes of the presently claimed invention, the hydroxyl number or OH number indicates the amount of potassium hydroxide, in milligrams, which is equivalent to the molar amount of acetic acid bound during the acetylation of one gram of the constituent in question.

For the purposes of the presently claimed invention, unless otherwise indicated, the hydroxyl number is determined experimentally by titration in accordance with DIN <NUM>-<NUM>.

For the purposes of the presently claimed invention, the mass-average (Mw) and number-average (Mn) molecular weight is determined by means of gel permeation chromatography at <NUM>° C, using a high-performance liquid chromatography pump and a refractive index detector. The eluent used was tetrahydrofuran with an elution rate of <NUM>/min. The calibration is carried out by means of polystyrene standards.

For the purposes of the presently claimed invention, '% by weight' or 'wt. % 'as used in the presently claimed invention is with respect to the total weight of the coating composition. Further, the sum of wt. -% of all the compounds, as described herein, in the respective components adds up to <NUM> wt.

The measurement techniques described hereinabove and herein are well known to a person skilled in the art and therefore do not limit the presently claimed invention.

An aspect of the presently claimed invention describes a polyurethane polymer which is obtainable by.

In a preferred embodiment of the presently claimed invention, the molar ratio of the at least one isocyanate-functional prepolymer (A) to the at least one compound of general formula (I) described herein is in the range of ≥<NUM> to ≤ <NUM>. In a more preferred embodiment of the presently claimed invention, the molar ratio of the at least one isocyanate-functional prepolymer (A) to the at least one compound of general formula (I) described herein is in the range of ≥<NUM> to ≤<NUM>.

The polyurethane polymer of the presently claimed invention is obtainable by (i) preparation of at least one isocyanate-functional prepolymer (A). The at least one isocyanate-functional prepolymer (A) is obtained by reacting a mixture comprising at least one polyisocyanate (B) and at least one alkanolamine (C).

In an embodiment of the presently claimed invention, the polyisocyanate (B) is an aliphatic polyisocyanate. In another embodiment of the presently claimed invention, the aliphatic polyisocyanate (B) is modified by an at least one group selected from an allophanate group, a biuret group, an uretdione group, an isocyanurate group and/or an iminooxadiazinedione group.

In a preferred embodiment of presently claimed invention, the polyisocyanate (B) is selected from the group consisting of <NUM>,<NUM>-hexamethylene diisocyanate (HDI), methylene dicyclohexyl diisocyanate, tetramethylene diisocyanate, <NUM>,<NUM>-pentamethylene diisocyanate, <NUM>,<NUM>,<NUM>- (or <NUM>,<NUM>,<NUM>-) trimethyl-<NUM>,<NUM>-hexamethylene diisocyanate, hydrogenated methylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI). In another preferred embodiment of presently claimed invention, the polyisocyanate (B) is selected from the group consisting of <NUM>,<NUM>-hexamethylene diisocyanate (HDI), methylene dicyclohexyl diisocyanate, tetramethylene diisocyanate, <NUM>,<NUM>-pentamethylene diisocyanate, <NUM>,<NUM>,<NUM>- (or <NUM>,<NUM>,<NUM>-) trimethyl-<NUM>,<NUM>-hexamethylene diisocyanate, hydrogenated methylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI) modified by one allophanate group, biuret group, uretdione group, isocyanurate group and/or iminooxadiazinedione group. In a more preferred embodiment of presently claimed invention, the polyisocyanate (B) is selected from the group consisting of <NUM>,<NUM>-hexamethylene diisocyanate (HDI), hydrogenated methylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI) or <NUM>, <NUM>-hexamethylene diisocyanate (HDI), hydrogenated methylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI) all of which are unmodified or modified by at least one group selected from an allophanate group, a biuret group, an uretdione group, an isocyanurate group and/or an iminooxadiazinedione group.

In another preferred embodiment of presently claimed invention, the polyisocyanate (B) is selected from the group consisting of <NUM>,<NUM>-hexamethylene diisocyanate (HDI), and <NUM>,<NUM>-pentamethylene diisocyanate, all of which are unmodified or modified by at least one group selected from an allophanate group, a biuret group, an uretdione group, an isocyanurate group and/or an iminooxadiazinedione group.

In another embodiment of the presently claimed invention, the alkanolamine (C) is selected from the group consisting of triethanolamine, triisopropanolamine, N-methyl-ethanolamine, N-ethyl-ethanolamine, N-butyl-ethanolamine, N-methyl-diethanolamine, N-ethyl-diethanolamine, N-butyl-diethanolamine and N,N-dimethylethanolamine.

In a preferred embodiment of the presently claimed invention, the alkanolamine (C) is selected from the group consisting of N,N-dimethylethanolamine, N-butyl-diethanolamine, N-methyl-ethanolamine, N-ethyl-ethanolamine, N-butyl-ethanolamine, N-methyl-diethanolamine and N-ethyl-diethanolamine.

In an embodiment of the presently claimed invention, the mixture comprises at least one hydroxy-functional polymer (D) selected from the group consisting of polyethylene glycol monoalkyl ether and polypropylene glycol monoalkyl ether.

In another embodiment of the presently claimed invention, the hydroxy-functional polymer (D) has a weight average molecular weight in the range of ≥ <NUM>/mol to ≤ <NUM>/mol, determined according to gel permeation chromatography against a polystyrene standard. In a preferred embodiment of the presently claimed invention, the hydroxy-functional polymer (D) has a weight average molecular weight in the range of ≥<NUM>/mol to ≤<NUM>/mol.

In a yet another embodiment of the presently claimed invention, the hydroxy-functional polymer (D) has a hydroxyl number in the range of ≥ <NUM> KOH/g to ≤ <NUM> KOH/g, determined according to DIN <NUM>-<NUM>. In a preferred embodiment of the presently claimed invention, the hydroxy-functional polymer (D) has a hydroxyl number in the range of ≥ <NUM> KOH/g to ≤ <NUM> KOH/g, determined according to DIN <NUM>-<NUM>.

The polyurethane polymer of the presently claimed invention is obtainable by (i) preparation of at least one isocyanate-functional prepolymer (A) by reacting a mixture comprising at least one polyisocyanate (B) and at least one alkanolamine (C) and (ii) subsequent reaction of the at least one isocyanate-functional prepolymer (A) with at least one compound of general formula (I),
<CHM>
wherein,.

In an embodiment of the presently claimed invention, R1, R2, R3 and R4 in formula (I), independent of each other, are selected from the group consisting of hydrogen, -F, -Cl, -CN, -Br, -NH2, -NHR and -NRR', wherein at least one of R1, R2, R3 and R4 is selected from the group consisting of -NH2 and-NHR.

In another embodiment of the presently claimed invention, the compound of general formula (I) is selected from the group consisting of <NUM>-aminosalicylic acid, <NUM>-aminosalicylic acid, <NUM>-aminosalicylic acid and <NUM>-aminosalicylic acid, and sodium salts thereof.

In a preferred embodiment of the presently claimed invention, a polyurethane polymer is obtainable by.

In another preferred embodiment of the presently claimed invention, a polyurethane polymer is obtainable by.

Another aspect of the presently claimed invention describes an aqueous composition comprising at least one polyurethane polymer described herein and water. For the purposes of the presently claimed invention, the aqueous composition is a dispersion or colloidal solution.

In an embodiment of the presently claimed invention, the aqueous composition comprises at least one acid selected from the group consisting of inorganic acids and organic acids.

In a preferred embodiment of the presently claimed invention, the inorganic acid is selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, phosphorous acid, phosphinic acid, polyphosphoric acid, perchloric acid, nitric acid, nitrous acid, sulphurous acid, chloric acid, chlorous acid and hypochlorous acid.

In another preferred embodiment of the presently claimed invention, the organic acid is selected from the group consisting of acetic acid, formic acid, propionic acid, butanoic acid, benzoic acid, phthalic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, lactic acid, citric acid, uric acid and malic acid. In a most preferred embodiment of the presently claimed invention, the at least one acid is selected from the group consisting of phosphorous acid, polyphosphoric acid and acetic acid.

In another embodiment of the presently claimed invention, the aqueous composition comprises at least one organic solvent (E). In a preferred embodiment of the presently claimed invention, the at least one organic solvent (E) is selected from the group consisting of n-methyl-<NUM> pyrrolidone, ethylene glycol dimethyl ether, diethylene glycol methyl ether, propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol butyl ether and tripropylene glycol butyl ether.

In a preferred embodiment of the presently claimed invention, an aqueous composition is provided comprising at least one polyurethane polymer described herein, water and at least one acid selected from the group consisting of inorganic acids and organic acids. In another preferred embodiment of the presently claimed invention, an aqueous composition is provided comprising at least one polyurethane polymer described herein, water, at least one acid selected from the group consisting of inorganic acids and organic acids, and at least one organic solvent (E).

In a more preferred embodiment of the presently claimed invention, an aqueous composition is provided comprising at least one polyurethane polymer described herein, water and at least one acid selected from the group consisting phosphorous acid, polyphosphoric acid and acetic acid.

For purposes of the presently claimed invention, the aqueous composition is preferably produced by mixing of the components described hereinabove. The mixing may take place by means of mixers or stirrers known to a skilled person at ambient temperature conditions. The mixing can be carried out either batch-wise or continuously.

An aspect of the presently claimed invention is directed to a metal pre-treatment composition comprising the aqueous composition described herein and at least one water-soluble metal salt or metal.

In a preferred embodiment of the presently claimed invention, the amount of the at least one polyurethane polymer in the metal pre-treatment composition is in the range of ≥<NUM> wt. % to ≤ <NUM> wt. %, based on the total weight of the metal pre-treatment composition. In a more preferred embodiment of the amount of the at least one polyurethane polymer in the metal pre-treatment composition is in the range of ≥<NUM> wt. % to ≤<NUM> wt. %, based on the total weight of the metal pre-treatment composition.

In a preferred embodiment of the presently claimed invention, the at least one water soluble metal salt is selected from the group consisting of titanium salts, iron salts, zirconium salts and manganese salts.

In another preferred embodiment of the presently claimed invention, the at least one metal is selected from the group consisting of titanium, iron, zirconium and manganese.

In yet another preferred embodiment of the presently claimed invention, the amount of the at least one water soluble metal salt or metal in the metal pre-treatment composition is in the range of ≥<NUM> wt. % to ≤ <NUM> wt. %, based on the total weight of the metal pre-treatment composition. In a more preferred embodiment of the presently claimed invention, the amount of the at least one water soluble metal salt or metal in the metal pre-treatment composition is in the range of ≥<NUM> wt. % to ≤ <NUM> wt. %, based on the total weight of the metal pre-treatment composition.

In another preferred embodiment of the presently claimed invention, the amount of water in the metal pre-treatment composition is in the range of ≥<NUM> wt. % to ≤ <NUM> wt. %, based on the total weight of the metal pre-treatment composition. In a more preferred embodiment of the presently claimed invention, the amount of water in the metal pre-treatment composition is in the range of ≥<NUM> wt. % to ≤ <NUM> wt. %, based on the total weight of the metal pre-treatment composition.

In another preferred embodiment of the presently claimed invention, the pH of the metal pre-treatment composition is in the range ≥<NUM> to ≤ <NUM>, In a more preferred embodiment of the presently claimed invention, the pH of the metal pre-treatment composition is in the range ≥<NUM> to ≤ <NUM>.

In a preferred embodiment of the presently claimed invention, a metal pre-treatment composition is provided comprising an aqueous composition described herein and at least one water-soluble metal salt selected from the group consisting of titanium salts, iron salts, zirconium salts and manganese salts. In another preferred embodiment of the presently claimed invention, a metal pre-treatment composition is provided comprising an aqueous composition described herein and at least one metal selected from the group consisting of titanium, iron, zirconium and manganese.

In a preferred embodiment of the presently claimed invention, a metal pre-treatment composition is provided comprising an aqueous composition described herein and at least one water-soluble metal salt or metal, wherein the pH of the metal pre-treatment composition is in the range ≥<NUM> to ≤ <NUM>.

The pH of the metal pre-treatment composition is acidic. The pH value of the metal pre-treatment composition may be adjusted with addition of pH regulators. The pH regulators or adjusting agents is selected preferably from acetic acid and phosphonic acid. The amount of the pH regulator in the metal pre-treatment composition is in the range of ≥<NUM> wt. % to ≤ <NUM> wt. %, based on the total weight of the metal pre-treatment composition. Optionally water dispersible or water soluble resins are added to the metal pre-treatment composition to provide toughness and sealing. The amount of the water soluble resin in the metal pre-treatment composition is in the range of ≥<NUM> wt. % to ≤ <NUM> wt. %, based on the total weight of the metal pre-treatment composition.

For the purposes of the presently claimed invention, the metal pre-treatment composition may further comprise additives such as surfactants, emulsifiers, lubricity enhancers, fungicides, stability enhancers, levelling agents, anti-friction agents, lubricants, dry lubes, rust preventives and cleaners. The amount of the additives in the metal pre-treatment composition is in the range of ≥<NUM> wt. % to ≤ <NUM> wt. %, based on the total weight of the metal pre-treatment composition. The metal pre-treatment compositions of the presently claimed invention may be used for permanent coating of metal surfaces. The use of the metal pre-treatment composition as metalworking fluid is especially preferred.

For the purposes of the presently claimed invention, the metal surface to be treated preferably comprises aluminum, an aluminum alloy, steel and/or galvanized steel. The preferred metal to be treated includes but are not limited to aluminum alloys, Cu, Si, Mg and/or Zn and the galvanized steel that may be hot-dipped or electrolytically galvanized steel. More preferably, the surface to be treated comprises a mix of different metals, e.g. areas of aluminum / an aluminum alloy as well as areas of (galvanized) steel.

Another aspect of the presently claimed invention is directed to a use of a metal pre-treatment composition described herein for coating a metal substrate.

For the purposes of the presently claimed invention, the metal surface may also be a metal surface coated with a conversion or passivation layer. Preferably, however, it is not coated with a conversion or passivation layer.

For the purposes of the presently claimed invention, the aqueous composition or the metal pre-treatment composition described herein can preferably be applied as a coating to a metal substrate. Representative examples of the application methods include, but are not limited to, rolling, spraying, spreading, pouring dipping, electroplating. embedding and impregnating.

For the purposes of the presently claimed invention, a metal surface treatment process comprises at least one of the following steps:.

wherein the temperature for curing is in the range of from ≥<NUM> to ≤ <NUM>, preferably in the range of from ≥<NUM> to ≤ <NUM>.

The degreasing step (i) is performed to remove dirt and oil attached onto the surface and a dipping treatment is performed with a degreasing agent which is phosphorous free and nitrogen free for about several minutes at a temperature of <NUM> to <NUM>. The rinsing step (ii) is performed by spraying a huge amount of washing water at least once to wash the degreasing agent after the degreasing step. The metal pre-treatment conditions are not particularly limited and may be performed by contacting the metal pre-treatment composition with the metal surface under standard conditions. The pre-treatment is carried out at a temperature in the range of from ≥<NUM> to ≤ <NUM>, preferably in the range of from ≥<NUM> to ≤ <NUM>. The metal surface treatment time is preferably in the range of from <NUM> second to <NUM> seconds, preferably in the range of from <NUM> seconds to <NUM> seconds. The method by which the metal pre-treatment composition and the metal surface is brought into contact is selected from, but is not limited to dipping method, spraying method, roll coating method and flow mechanism method. The curing can be carried by thermal curing and has no peculiarities in terms of method, but instead takes place in accordance with the customary and known methods, such as heating in a forced air oven or irradiation with IR lamps. This thermal curing may also take place in stages. Another preferred curing method is that of curing with near infrared (NIR radiation). The curing preferably takes place advantageously at lower temperatures from ≥ <NUM> to ≤ <NUM>, more preferably from ≥ <NUM> to ≤ <NUM>, and enables protection of heat sensitive components.

An aspect of the presently claimed invention is directed to a method for pre-treating a metal substrate comprising at least the step of contacting a metal substrate with the metal pre-treatment composition described herein.

In a preferred embodiment of the presently claimed invention, the method for pre-treating a metal substrate further comprises subsequently contacting the metal substrate with at least one paint.

In a preferred embodiment of the presently claimed invention, a method for pre-treating a metal substrate is provided comprising at least the step of contacting a metal substrate selected from the group consisting of cold rolled sheet, aluminum, aluminum alloys, galvanium hot dip zinc galvanized steel, electrolytically galvanized steel, Al-Zinc magnesium steel, iron and zinc and multi-metal alloys with the metal pre-treatment composition described herein.

In an embodiment of the presently claimed invention, the metal substrate is selected from the group consisting of cold rolled sheet, aluminum, aluminum alloys, galvanium hot dip zinc galvanized steel, electrolytically galvanized steel, Al-Zinc magnesium steel, iron and zinc and multi-metal alloys.

Another aspect of the presently claimed invention is directed to coated metal substrate obtainable by a method for pre-treating a metal substrate described herein.

The aqueous composition or the metal pre-treatment composition of the presently claimed invention advantageously provide corrosion protection, humidity resistance, stability. The metal pre-treatment composition of the presently claimed invention also enable coagulation of metals for treatment. For the purposes of the presently claimed invention, the polyurethane polymer described herein is less sensitive to metal alloy variation in an intermetallic composition and are stable by incorporating the solubility groups into the oligomers. The polymer described herein has strong affinity to the metals and enables strong binding to the metals under metal treatment application conditions. Depending on the intended metal surface treatment, the properties of the composition according to the invention may be tailored by adding different kinds of additives. Representative examples of additives include but are not limited to neutralizers, emulsifiers, lubricity enhancers, metal deactivators and/or stability enhancers for freeze/thaw cycles. Further on, the additives may serve for anticorrosion, pH-control, coupling, wetting, antimicrobial, antifungal, and/or against foam formation.

The presently claimed invention is illustrated in detail by non-restrictive working examples which follow. More particularly, the test methods specified hereinafter are part of the general disclosure of the application and are not restricted to the specific working examples.

<NUM> of Bayhydur® <NUM> and <NUM> of n-methyl-<NUM> pyrrolidone were added into a reaction flask (<NUM>). The above mixture was heated to <NUM>. Then, <NUM> of dimethyl ethanol amine was added into the reaction flask as two shots at equal amount within <NUM> minutes under agitation. The exotherm was observed and reaction flask was cooled to maintain the temperature in the range of <NUM> to <NUM> for <NUM> hours. The NCO content was checked, and the NCO peak was measured at <NUM>-<NUM> using Fourier-transform infrared spectroscopy (FTIR). The reaction mixture was cooled to <NUM>. <NUM> of sodium amino salicylic acid was pre-dissolved with <NUM> of n-methyl-<NUM> pyrrolidone and was slowly added into the flask. The temperature was controlled below <NUM>. The temperature was maintained at <NUM> for <NUM> hour after addition of the components. The NCO peak was re-measured to ensure all the NCO has been reacted. The batch was cooled below <NUM>. <NUM> of <NUM>% of H<NUM>PO<NUM> was added under agitation and stirred for <NUM> minutes. Then <NUM> DI (deionized water) water was added under agitation and stirred again for <NUM> minutes.

<NUM> of Bayhydur® <NUM>, <NUM> of n-methyl-<NUM> pyrrolidone and <NUM> of MPEG350 were added into a reaction flask (<NUM>). The above mixture was heated to <NUM> for <NUM> minutes. Then, <NUM> of dimethyl ethanol amine was added into the reaction flask as two shots at equal amount within <NUM> minutes under agitation. The exotherm was observed and cooled to maintain at <NUM> to <NUM> for <NUM> hours. The NCO content was checked, and NCO peak was measured at <NUM>-<NUM> using FTIR. The reaction flask was cooled to <NUM>. <NUM> of sodium amino salicylic acid was slowly added into the flask and the temperature was controlled below <NUM>. The temperature was maintained at <NUM> for <NUM> hour after the addition of the components. The NCO peak was measured again to ensure all the NCO has been reacted. The batch was cooled below <NUM>. <NUM> of <NUM>% of H<NUM>PO<NUM> was added under agitation and stirred for <NUM> minutes. Then <NUM> of DI water was added under agitation and stirred again for <NUM> minutes.

<NUM> of Bayhydur® <NUM>, <NUM> of n-methyl-<NUM> pyrrolidone and <NUM> of MPEG350 were added into a reaction flask (<NUM>). The above mixture was heated to <NUM> for <NUM> minutes. Then <NUM> of dimethyl ethanol amine was added into the flask slowly within <NUM> minutes under agitation. The exotherm was observed and cooled to maintain at <NUM> to <NUM> for <NUM> hours. The NCO content was checked, and NCO peak was measured at <NUM>-<NUM> using FTIR. The flask was cooled to <NUM>. <NUM> of sodium amino salicylic acid was pre-dissolved with <NUM> of n-methyl-<NUM> pyrrolidone and was slowly added into the flask. The temperature was controlled below <NUM>. The temperature was maintained at <NUM> for <NUM> hour after the addition of the components. The NCO peak was measured again to ensure all the NCO has been reacted. The batch was cooled below <NUM>. <NUM> of acetic acid (<NUM>%) was added under agitation and stirred for <NUM> minutes. Then <NUM> of DI water was added under agitation and stirred again for <NUM> minutes.

<NUM> of Bayhydur® <NUM>, <NUM> of n-methyl-<NUM> pyrrolidone, <NUM> of MPEG350 were added into a reaction flask (<NUM>). The above mixture was heated to <NUM> for <NUM> minutes. <NUM> of dimethyl ethanol amine was added into the flask slowly within <NUM> minutes under agitation. The exotherm was observed and cooled to maintain at a temperature in the range of <NUM> to <NUM> for <NUM> hours. A second flask (<NUM>) was loaded with <NUM> of butylethanol amine and the above mixture was slowly addition into a second flask and maintained at a temperature around <NUM> to <NUM> for additional <NUM> hour after the addition of the components. The NCO content was checked, and the NCO peak was measured at <NUM>-<NUM> with FTIR. <NUM> of sodium amino salicylic acid was pre-dissolved with <NUM> of n-methyl-<NUM> pyrrolidone and was slowly added into a second flask. The temperature was controlled below <NUM>. The temperature was maintained at <NUM> for <NUM> hour after the addition of the components. The NCO peak was measured again to ensure all the NCO has been reacted. The batch was cooled below <NUM>. <NUM> of H<NUM>PO<NUM> (<NUM>%) was added under agitation and stirred for <NUM> minutes. Then <NUM> of DI water was added under agitation and stirred again for <NUM> minutes.

FTIR of oligomer A indicated the overlapping of OH O-H Stretch, (broad, s) with Urea N-H stretch <NUM>-<NUM> (M) at wavenumber range (<NUM> to <NUM>) is shown in <FIG>. Free OH existed in Oligomer A.

The prepared formula was put inside oven at <NUM> C for <NUM> weeks. Stability was measured by observing the sludge formation and monitoring the solution viscosity change.

The Cross-Hatch adhesion was determined in accordance with the Standard Test Method ASTM D3359. This test is for assessing the adhesion of relatively ductile coating films to metallic substrates by applying and removing pressure-sensitive tape (<NUM> # <NUM> tape) over cuts made in the film. A rating is provided from 5B to 0B, where 5B is the best and 0B is the worst.

The T-Bend was determined in accordance with the Standard Test Method ASTM D4145. This test method describes a procedure for determining the flexibility and adhesion of organic coatings (paints) on metallic substrates that are deformed by bending when the sheet is fabricated into building panels or other products. No tape removal with #M # <NUM> tape is considered as pass.

The Reverse impact was determined in accordance with the Standard Test Method ASTM D2794. The weight loads (Ibs) 3X gauge was tested on all substrates except aluminum which was <NUM>. This method tests the flexible characteristics of the paint film and its ability to stretch. The deformed films are taped with <NUM> #<NUM> tape. No paint taping off is considered as pass.

The corrosion resistance was determined by Neutral Salt Spray (NSS) in accordance with the Standard Test Method ASTM D1654. According to ASTM D1654 protocol, <NUM> measurements along and across the scribe are measured, the scribe width is subtracted, and then divided by <NUM> to determine the creepage. The values in millimeter (mm) are averaged of creepage. The readings are validated only with specified testing hours.

Claim 1:
A polyurethane polymer which is obtainable by
(i) preparation of at least one isocyanate-functional prepolymer (A) by reacting a mixture comprising at least one polyisocyanate (B) and at least one alkanolamine (C);
(ii) subsequent reaction of the at least one isocyanate-functional prepolymer (A) with at least one compound of general formula (I),
<CHM>
wherein,
R1, R2, R3 and R4, independent of each other, are selected from the group consisting of hydrogen, -C(=O)-OH, -C(=O)-OM<NUM>, -OSO<NUM>H, -OSO<NUM>M<NUM>, -OH, -OM<NUM>, - C(=O)-H, -O-C<NUM>-<NUM>-alkyl, -F, -Cl, -CN, -Br, -NH<NUM>, -NHR and -NRR', wherein at least one of R1, R2, R3 and R4 is selected from the group consisting of -NH<NUM> and -NHR M<NUM> is selected from the group consisting of hydrogen and metal cations selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra),
M<NUM> is selected from the group consisting of hydrogen and metal cations selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra),
M<NUM> are, identical or different, a metal cation selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba),
and radium (Ra), and
R and R' are, identical or different, linear or branched, unsubstituted C<NUM>-C<NUM> alkyl.