COATING COMPOSITION FOR A METAL SURFACE

TECHNICAL FIELD
[0001] The present disclosure, in general, relates to the field of preventive coatings and, in particular, relates to a coating composition for a metal surface and a coated steel having the coating composition on its surface.
[0002] The coating has been developed for galvannealed steel (GA) to prevent the corrosion during exposure in fuel medium. This coating on GA not allowing the corrosive ions and fuel to interact with metal surface. The coating is applied after galvannealing and it can be applied online and offline both way

BACKGROUND
[0003] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0004] Steel consumption in automobile industry steel is around 60%. It is used in body structure, panels, doors, trunk closures, drive train, suspension, wheels, tyres, fuel tank, steering and breaking systems. The material requirement for fuel tank needs to be fuel resistance from internal side while external side it needs paintability for corrosion protection from environment. The following main properties are required for a material to be used as fuel tank a). inner side: solvent/fuel resistance b) Outer side: environment corrosion protection c) weldability (MIG, SEAM and Soldering) d) Forming. The Pb-Sb-alloy-coated steel (terne sheet) was used as fuel tank material in automobile industry. The terne coat sheet has poor fuel resistance in methanol blended fuels. The terne sheet had good corrosion, fabrication and welding properties required for fuel tank manufacturing. Since the use of Pb in terne sheet had environmental pollution issues therefore it is not in present use. The use of lead was banned in automobile industry in 2000 in EU.
[0005] After the terne sheet restriction of use in automobile industry lead free coating steel sheets are in use for fuel tank application. These are:
1. Sn-Zn coated steel (ECOKOTE-S)
2. Aluminium coated sheet
3. Electrogalvanised material (Zn-Ni)
4. Galvannealed material (GA)
5. Chromate passivation with all (1-4)
6. Chrome free passivation with all (1-4)
7. Epoxy coated combination with all (1-6)
8. Polymer coated with all (1-6)
[0006] In present scenario, different types of metallic and polymer coatings with different combination were developed for fuel tank application. To get higher life of fuel tank, it is imperative to use coated metal sheets with better fuel resistance. The internal surface of the fuel tank is exposed to fuel which produces rust/corrosion product/particles which can chock the fuel injection system of vehicle. This problem has complaint claim during warranty period.
[0007] JP5989049 discloses polyolefin based resin coating with cross linking agent which has poor solubility in fuel.
[0008] JP3977756 disclosed coating on the zinc or aluminium based plated steel for the fuel tank application. The thickness of the film in range of .001-5 micron. The coating mainly contains epoxy resin, amine functionality, Polyuretahne resin, phosphoric acid and silane coupling agent.
[0009] JP2007162089 discloses the surface treated steel sheet for high formable and high strength for automobile fuel tank. In this invention, the chemical conversion treatment was done over the galvanized sheet. Afterwards, amine modified epoxy resin containing metallic powder on onside of surface while on other side acrylic emulsion containing silica based coating was applied.
[0010] JP2007254796 disclosed two layer of coating on zinc plated steel for fuel tank application. The one layer of composite film composed of metallic powder of Al and Ni in amine modified resin. The other layer(passivation) contains mainly Al, Mn metal phosphate and phosphoric acid.
[0011] JP4151228 discloses coating for zinc plated steel for fuel tank use. The zinc plated layer was first chromated and afterthat amine modified epoxy resin with Al and Ni metal powder based coating was applied on one side. Other sider on chromating the acrylic emulsion applied.
[0012] JP2002307011 discloses aquous coating composition for gasoline tank. The coating comprises epoxy modified alkyd resin, melamine resin, rust preventive pigment and aluminium phosphate.
[0013] KR101400659 discloses resin coated steel plate for fuel tank of vehicle with higher life. The coating was applied on base steel plate. The coating comprises mainly acryl resin, epoxy resin, silica, metallic compound, aromatic triazole, titanium coupling agent, ammonium phosphate, hardening agent, wetting agent and solvent.
[0014] JP2002363500 discloses rust proof coating material composition for fuel tank. The coating contains water based resin, pigment, rust proofing agent, fillers and additives.
[0015] KR100544725 discloses resin coated steel plate for fuel tank. It comprises water soluble phenoxy resin, melamine resin, colloidal silica,chromic acid and wax. Thickness of the film is 1-10 micron. The calcining of the steel coated plate at 160-250 deg C and cooling afterthat.
[0016] KR100928834 discloses resin coated steel sheet for fuel tank in automobile. The resin coating contains melamine resin, colloidal silica, acryl modified styrene butadiene rubber, acrylic acid, phenoilc resin. This coating were precisely applied on Zn or Zn-Ni chromate treated steel. The thickness of the film was 1-10 micron.
[0017] KR100643355 discloses Zn and Zn alloy plated steel with polymer coating for fuel tank fabrication. The polymer layer composed of phosphoric ester, silicate compound, titanium compound, acryl resin, phenoxy resin and melamine resin.

OBJECTS OF THE DISCLOSURE
[0018] In view of the foregoing limitations inherent in the state of the art, some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed hereinbelow.
[0019] It is a general object of the present disclosure to provide a material was developed for fuel tank application for automobile sector. This material has all three properties required for fuel tank a) Internal and external corrosion resistance, b) weldability, and c) press formability. The internal corrosion resistance includes resistance to petrol, diesel, biofuels, formic acid, ethanol, isooctane and methanol and combination thereof.
[0020] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.

SUMMARY
[0021] This summary is provided to introduce concepts related to a coating composition for a metal surface and a coated steel having the caoting composition on its surface. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0022] In an embodiment, the present disclosure relates to a coating composition for a metal surface, comprising 4-25 a water based poly condensed silane solution comprising of one or more organo-functional silanes, 0.01-2 a hydrolysing agent, 0.1-3 a flash rust inhibitor, 0.05-5 a curing agent, 0.5-30 film forming agent, 0.5-20 a pigment, 0-2 a defoamer and leveling agent, 0-15 a solvent, 0-3 a corrosion inhibitor (all in wt.%); and the balance being water based upon 100 percent by weight of the total coating composition.
[0023] In an aspect, the hydrolysing agent is selected from the group consisting of phosphoric acid, nitric acid, and acetic acid.
[0024] In an aspect, the one or more organofunctional silanes is at least one of glycidoxypropyltrimethoxysilane (GPTMS) 0.5-20, tetraethylorthosilicate (TEOS) 0-5, vinyl trimethoxy silane (VTMS) 0.1-20, mercaptopropyl trimethoxy silane 0.5-10, and aminopropyl triethoxy silane 0.1-10 (all in wt.%)
[0025] In an aspect, the water based poly condensed silane solution comprising one or more organo-functional silanes is hydrolised at pH 2-6.5 for 1-16 hours at room temperature with continuous stirring at a speed of 200-600 rpm.
[0026] In an aspect, the flash rust inhibitor is selected from the group consisting of sodium nitrite, benzotriazole, 10-25% of C12-C14 (2-benzothiazolylthio) succinic acid tertiary amine salts, 10-25% of ethoxylated tridecylalcohol phosphate-comprising monoethanolamine salts, 10-25% of zinc salts of branched (C6-C19) fatty acids, <2.5% of zinc salts of naphthenic acid, 10-25% morpholine benzoate, and mixtures thereof.
[0027] In an aspect, the curing agent is butyl diethanol amine or a derivative of butyl diethanol amine.
[0028] In an aspect, the film forming agent is selected from the group consisting of ethylene glycol, poly ethylene glycol, ethyl silicate, and mixtures thereof.
[0029] In an aspect, the defoamer and leveling agent is a silicon solution or a derivative of a silicon solution.
[0030] In an aspect, the pigment is selected from the group consisting of zinc oxide, silica, alumina, cerium nitrate, cerium dibutyl phosphate, zirconium nitrate, lanthanum nitrate, and a combination thereof.
[0031] In an aspect, the corrosion inhibitor is Aluminium salt or urea or a combination thereof.
[0032] In an aspect, the Aluminum salt is inhibitor is Aluminum nitrate.
[0033] In an aspect, the solvent is ethoxy ethanol.
[0034] In an aspect, pH of the coating is 3 to 9.
[0035] In an embodiment, the present disclosure relates to a coated steel comprising a steel substrate; and a coat of 500 nm to 200 microns over the steel substrate, the coat comprising 4-25 a water based poly condensed silane solution comprising of one or more organo-functional silanes, 0.01-2 a hydrolysing agent, 0.1-3 a flash rust inhibitor, 0.05-5 a curing agent, 0.5-30 film forming agent, 0.5-20 a pigment, 0-2 a defoamer and leveling agent, 0-15 a solvent, 0-3 a corrosion inhibitor (all in wt.%), the balance being water based upon 100 percent by weight of the total coating composition.
[0036] In an aspect, the steel substrate is fuel tank.
[0037] In an aspect, the steel substrate is a galvannealed steel.
[0038] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
[0039] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
[0040] FIG. 1 illustrates an Electrochemical Impedance Spectroscopy (EIS) on nyquist plot of the examples 1, 2, 3 and 4, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0041] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0042] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0043] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes”, “consisting” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0044] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0045] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0046] Embodiments explained herein pertain to a coated steel product developed for fuel tank application for automobile industry. The coated steel product is more specifically polymer coated galvannealed (GA) sheets. The coated GA material is evaluated for corrosion property for fuel tank application. This material has good corrosion resistance in salty atmosphere and exhibited superior paintability. This material was evaluated for fuel resistance. It exhibited excellent resistance to petrol, diesel, biofuels, formic acid, ethanol, isooctane and methanol and combination thereof. This coating is only few microns in thickness therefore material is weldable and press formable.
[0047] Further, aluminium metal of fuel tank application in automobile industry corrodes and form aluminium oxide passivation layer. The aluminium oxide layer protects aluminium from further corrosion (self protection layer). It is impervious and adhere strongly to parent metal.
[0048] In this present disclosure, in-situ alumina is formed in coating network. As such dissolution or making stable emulsion is difficult for alumina. Therefore, aluminium salt and and organic reducing agent (Urea) are utilized in the present disclosure. Since coating solution proposed in the present disclosure is acidic in nature so in an acidic medium, aluminium nitrate forms a complex with urea via a reaction of the NO3 anion with the urea amino group, as shown below:
2Al(NO3)3 . 9H2O + 5CH4N2O = Al2O3 + 8N2 + 5CO2 + 28H2O
[0049] This reaction leads to formation of alumina type of material which helps to reduce the porosity of the coating. Also, this material is chemically inert.
[0050] In the below description all the chemical ingredients were used as such. The coating composition and process of synthesizing the coating was given below. The said coating can be applied by dip or spray method. The coated samples were cured at elevated temperature of 80-200 °C. The thickness of coating was maintained up to 25 micron precisely in the range of 0.1 to 10 micron preferably 0.1-3 micron. The benefit of coating can be used by having one sided and both sided coating on the steel sheet.
[0051] In an embodiment, the present disclosure relates to a coating composition for a metal surface, comprising 4-25 a water based poly condensed silane solution comprising of one or more organo-functional silanes, 0.01-2 a hydrolysing agent, 0.1-3 a flash rust inhibitor, 0.05-5 a curing agent, 0.5-30 film forming agent, 0.5-20 a pigment, 0-2 a defoamer and leveling agent, 0-15 a solvent, 0-3 a corrosion inhibitor (all in wt.%); and the balance being water based upon 100 percent by weight of the total coating composition.
[0052] In an aspect, the hydrolysing agent is selected from the group consisting of phosphoric acid, nitric acid, and acetic acid.
[0053] In an aspect, the one or more organofunctional silanes is at least one of glycidoxypropyltrimethoxysilane (GPTMS) 0.5-20, tetraethylorthosilicate (TEOS) 0-5, vinyl trimethoxy silane (VTMS) 0.1-20, mercaptopropyl trimethoxy silane 0.5-10, and aminopropyl triethoxy silane 0.1-10 (all in wt.%)
[0054] In an aspect, the water based poly condensed silane solution comprising one or more organo-functional silanes is hydrolised at pH 2-6.5 for 1-16 hours at room temperature with continuous stirring at a speed of 200-600 rpm.
[0055] In an aspect, the flash rust inhibitor is selected from the group consisting of sodium nitrite, benzotriazole, 10-25% of C12-C14 (2-benzothiazolylthio) succinic acid tertiary amine salts, 10-25% of ethoxylated tridecylalcohol phosphate-comprising monoethanolamine salts, 10-25% of zinc salts of branched (C6-C19) fatty acids, <2.5% of zinc salts of naphthenic acid, 10-25% morpholine benzoate, and mixtures thereof.
[0056] In an aspect, the curing agent is butyl diethanol amine or a derivative of butyl diethanol amine.
[0057] In an aspect, the film forming agent is selected from the group consisting of ethylene glycol, poly ethylene glycol, ethyl silicate, and mixtures thereof.
[0058] In an aspect, the defoamer and leveling agent is a silicon solution or a derivative of a silicon solution.
[0059] In an aspect, the pigment is selected from the group consisting of zinc oxide, silica, alumina, cerium nitrate, cerium dibutyl phosphate, zirconium nitrate, lanthanum nitrate, and a combination thereof.
[0060] In an aspect, the corrosion inhibitor is Aluminium salt or urea or a combination thereof.
[0061] In an aspect, the Aluminum salt is inhibitor is Aluminum nitrate.
[0062] In an aspect, the solvent is ethoxy ethanol.
[0063] In an aspect, pH of the coating is 3 to 9.
[0064] In an embodiment, the present disclosure relates to a coated steel comprising a steel substrate; and a coat of 500 nm to 200 microns over the steel substrate, the coat comprising 4-25 a water based poly condensed silane solution comprising of one or more organo-functional silanes, 0.01-2 a hydrolysing agent, 0.1-3 a flash rust inhibitor, 0.05-5 a curing agent, 0.5-30 film forming agent, 0.5-20 a pigment, 0-2 a defoamer and leveling agent, 0-15 a solvent, 0-3 a corrosion inhibitor (all in wt.%), the balance being water based upon 100 percent by weight of the total coating composition.
[0065] In an aspect, the steel substrate is fuel tank.
[0066] In an aspect, the steel substrate is a galvannealed steel.

EXAMPLES
[0067] The present disclosure is described hereinafter with the help of the following examples. These examples are provided only for illustrating the present disclosure and should not be construed as limiting the scope of the present disclsoure. In an aspect, the galvannealed steel material is used for application of the coating solution of present disclosure. In another aspect, the Aluminum nitrate is used as corrosion inhibitor and the urea used as catalyst for corrosion inhibitor.
Example 1:
Coating chemicals Composition wt%
Condensed sol-gel product 4-25
Corrosion inhibitor AlNO3 1
Corrosion inhibitor catalyst (Urea) 1
Flash rust inhibitor 0.5
Curing agent 0-3
Solvent 0-10
Film forming agent 5
Wetting additive 0.25-2
Hydrolyzing catalyst 0-1
Water remaining

Example 2:
Coating chemicals Composition wt%
Condensed sol-gel product 4-25
Corrosion inhibitor AlNO3 2
Corrosion inhibitor catalyst (Urea) 1
Flash rust inhibitor 0.5
Curing agent 0-3
Solvent 0-10
Film forming agent 5
Wetting additive 0.25-2
Hydrolyzing catalyst 0-1
Water remaining

Example 3
Coating chemicals Composition wt%
Condensed sol-gel product 4-25
Corrosion inhibitor AlNO3 3
Corrosion inhibitor catalyst (Urea) 1
Flash rust inhibitor 0.5
Curing agent 0-3
Solvent 0-10
Film forming agent 5
Wetting additive 0.25-2
Hydrolyzing catalyst 0-1
Water remaining

Example 4
Coating chemicals Compostion wt%
Condensed sol-gel product 4-25
Corrosion inhibitor AlNO3 0
Corrosion inhibitor catalyst (Urea) 0
Flash rust inhibitor 0.5
Curing agent 0-3
Solvent 0-10
Film forming agent 5
Wetting additive 0.25-2
Hydrolyzing catalyst 0-1
Water remaining

[0068] The coating formulation of examples 1, 2, 3 and 4 are applied on Galvannealed (GA) steel substrate which provides uniform coating thickness in the range of 0.5 to 10 micron. The coated GA, as per examples, above are then evaluated for salt resistance in salt spray chamber and showed more than 100h white rust resistance life as per ASTM B117 standard.
[0069] The formed coated galvannealed steel sheet is then evaluated for foul fuel resistance for 200 days in petrol and diesel. The coated material showed excellent aggressive fuel protection.
[0070] The composition of the aggressive ethanol, aggressive methanol and foul fuel test were given below:
Composition of 1 liter of foul fuel test (CE10A):
900 ml of Petrol obtained from Petrol pump station + 100 ml of aggressive ethanol
Composition of 1 liter of foul fuel test (CE15A):
850 ml of Petrol obtained from Petrol pump station + 150 ml of aggressive ethanol
Composition of 1 liter of foul fuel test (CE40A):
600 ml of Petrol obtained from Petrol pump station + 400 ml of aggressive ethanol
Composition of 1 liter of foul fuel test (CE85A):
150 ml of Petrol obtained from Petrol pump station + 850 ml of aggressive ethanol
Composition of 1 liter of foul fuel test (100A):
1000 ml of aggressive ethanol
Composition of M20 : 800 ml petrol +200 ml aggressive methanol
Composition of M100 : 100 ml aggressive methanol
Composition of aggressive ethanol: 816.0 gm. (1.034 liters) of denatured ethanol, CDA 20 + 8.103 gm. (8.1 ml) ASTM D1193- type II water + 0.004 gm of sodium chloride + 0.021 gm. (11 microliters) of sulphuric acid + 0.061 gm.( 58 microlitre) of glacial acetic acid
Composition of aggressive methanol : 792.4 gm methanol commercial grade + 2.33 gm reagent water + 0.004 gm sodium chloride + 0.046 gm formic acid

[0071] FIG. 1 illustrates an Electrochemical Impedance Spectroscopy (EIS) on nyquist plot of the examples 1, 2, 3 and 4, in accordance with an embodiment of the present disclosure. Also, the following Table 1 shows a comparison of impedance of the examples 1, 2, 3 and 4 coating solution over GA substrate.

Table 1: Impedance of the examples 1, 2, 3 and 4 coating solution over GA substrate
Sample Impedance (kOhm)
Example 4 1.9
Example 1 6.6
Example 2 2.7
Example 3 1.95

[0072] Thus, the coating of the present disclosure has good adhesion with the galvannealed substrate. The coating application were done by roll coater, dip and spray method. The coating was applied on one or both side of galvannealed substrate. The coating cures within 30 seconds at 40-70 degees Celsius.
[0073] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0074] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
[0075] Furthermore, those skilled in the art can appreciate that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0076] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0077] While the foregoing describes various embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof. The scope of the present disclosure is determined by the claims that follow. The present disclosure is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

WE CLAIM:

1. A coating composition for a metal surface, comprising:
4-25 a water based poly condensed silane solution comprising of one or more organo-functional silanes, 0.01-2 a hydrolysing agent, 0.1-3 a flash rust inhibitor, 0.05-5 a curing agent, 0.5-30 film forming agent, 0.5-20 a pigment, 0-2 a defoamer and leveling agent, 0-15 a solvent, 0-3 a corrosion inhibitor (all in wt.%); and
the balance being water based upon 100 percent by weight of the total coating composition.
2. The coating composition as claimed in claim 1, wherein the hydrolysing agent is selected from the group consisting of phosphoric acid, nitric acid, and acetic acid.
3. The coating composition as claimed in claim 1, wherein the one or more organofunctional silanes is at least one of glycidoxypropyltrimethoxysilane (GPTMS) 0.5-20, tetraethylorthosilicate (TEOS) 0-5, vinyl trimethoxy silane (VTMS) 0.1-20, mercaptopropyl trimethoxy silane 0.5-10, and aminopropyl triethoxy silane 0.1-10 (all in wt.%)
4. The coating composition as claimed in claim 1, wherein the water based poly condensed silane solution comprising one or more organo-functional silanes is hydrolised at pH 2-6.5 for 1-16 hours at room temperature with continuous stirring at a speed of 200-600 rpm.
5. The coating composition as claimed in claim 1, wherein the flash rust inhibitor is selected from the group consisting of sodium nitrite, benzotriazole, 10-25% of C12-C14 (2-benzothiazolylthio) succinic acid tertiary amine salts, 10-25% of ethoxylated tridecylalcohol phosphate-comprising monoethanolamine salts, 10-25% of zinc salts of branched (C6-C19) fatty acids, <2.5% of zinc salts of naphthenic acid, 10-25% morpholine benzoate, and mixtures thereof.
6. The coating composition as claimed in claim 1, wherein the curing agent is butyl diethanol amine or a derivative of butyl diethanol amine.
7. The coating composition as claimed in claim 1, wherein the film forming agent is selected from the group consisting of ethylene glycol, poly ethylene glycol, ethyl silicate, and mixtures thereof.
8. The coating composition as claimed in claim 1, wherein the defoamer and leveling agent is a silicon solution or a derivative of a silicon solution.
9. The coating composition as claimed in claim 91, wherein the pigment is selected from the group consisting of zinc oxide, silica, alumina, cerium nitrate, cerium dibutyl phosphate, zirconium nitrate, lanthanum nitrate, and a combination thereof.
10. The coating composition as claimed in claim 1, wherein the corrosion inhibitor is Aluminium salt or urea or a combination thereof.
11. The coating composition as claimed in claim 11, wherein the Aluminum salt is inhibitor is Aluminum nitrate.
12. The coating composition as claimed in claim 1, where in the solvent is ethoxy ethanol.
13. The coating composition as claimed in claim 1, wherein pH of the coating is 3 to 9.
14. A coated steel comprising:
a steel substrate; and
a coat of 500 nm to 200 microns over the steel substrate, the coat comprising 4-25 a water based poly condensed silane solution comprising of one or more organo-functional silanes, 0.01-2 a hydrolysing agent, 0.1-3 a flash rust inhibitor, 0.05-5 a curing agent, 0.5-30 film forming agent, 0.5-20 a pigment, 0-2 a defoamer and leveling agent, 0-15 a solvent, 0-3 a corrosion inhibitor (all in wt.%), the balance being water based upon 100 percent by weight of the total coating composition.
15. The coated steel as claimed in 14, wherein the steel substrate is fuel tank.
16. The coated steel as claimed in claim 14, wherein the steel substrate ,