Field of the Invention:
The present invention reveals the composition of a temporary rust preventive coating. It is essentially designed to protect the surface of steel from the damaging effects of the environment and handling during transportation and storage.
Background of the Invention: In steel plant Precision Tubes are produced from CRCA sheets for various applications like automotive, boiler and general engineering. For all precision tubes products, rust preventive guarantee of six months is one of the major technical delivery conditions. The current practice being followed in tubes plant is post production oiling with rust preventive oil. Excess oil is drained out by keeping the tube bundles at an angle and finally the oiled tubes are docked for dispatch to the customer. This process apart from being very expensive also causes dent by additional handling, which damage the tube bundle. To eliminate oiling a suitable rust preventive coating with a suitable application technique is developed under this work.

Temporary protective coatings are widely used to protect the surfaces of various products parts, or components during manufacture, assembly, shipping, installation, or refinishing operations. The temporary protective coatings are used to prevent the damage from scratching, corrosion, sticking, or discoloration. The protective coatings are also used to simplify or enhance cleaning operations whereby surface contamination is eliminated by removal of temporary coatings.
The coating comprises of a base solution, anti rust oil and a phosphate salt as inhibitor. Further to this composition the newly invented application process is also incorporated in this invention.
US 2004/0009354A1 to Krepski etal describes a dry strippable coating composition which can be incorporated into a composite article and comprises dried water borne polyurethane dispersion including a release additive consisting of a releasing co-solvent or other selected release material. Dry stripping the coating composition from the substrate provides a thermoformed substrate and a thermoformed protective layer. The dry strippable coatings provide temporary protection for the surface of the various products and components during the manufacture, assembly, shipping, installation, painting and refinishing operations.

US 2008/0268140 Al to Akhtar et al. teach a composition of clear pigmented coating that is temporary and removable. It is especially designed to protect the surface of an automobile from damaging effects of the environment and also the damage caused by daily normal use. The coating composition is of 40 to 80% of cellulose acetate butyrate ester, 15 to 60% of an acrylic polymer and 2 to 10% of a sucrose acetate isobutyrate. The remover is a combination of tetrahydrofurfuryl alcohol, dibasic ester, diacetone alcohol, ethyl 3 ethoxypropionate; 2,2,4 trimethyl-1,3 pentanildiol monoisobutyrate, and white mineral oil.
US 2010/0183901 Al to Van Ginneken et al teaches an aqueous coating composition for forming a peelable temporary coating on a substrate, said aqueous coating composition comprising one water based film forming polymer, characterized in that the composition additionally comprises solid particles of amino based polymer.
Such coatings are suitable for temporary protection and/or decoration of motor vehicles and components thereof. The surface paint finishes of a new vehicle subjected to various types of damages both during assembly process and during transportation from the assembly plant to retail locations. Typical sources Includes acid rain, bird droppings

and rail dust, a cloud of hard, abrasive particles which rises from rail bed as trail passes over the rails, or from the electrical pickups scraping on the overhead power lines.
Examples of suitable water based film forming polymers are polyurethanes, polyesters, polycarbonates, and polymers prepared by polymerization of olefenically unsaturated monomers, such as poly (meth)acrylates or copolymers of vinyl acetate. It is also possible to use mixtures and/or hybrids of these types of film forming polymers. The solid particles of an amino based polymer are generally present in the coating composition in an amount of at least 1, or at least 2, or even at least 4% by weight, calculated on total weight of composition. The upper limit of the amount of the particles suitably is 25%, or 20%, or 14% by weight, calculated on total weight of the composition. The average particle size generally is in the range of 1pm to 150pm.
US Patent 5495462 to Salamon et al describes an aqueous base coating composition for forming strippable, protective coating for protecting surfaces, such as glass, metal, ceramic, plastic or other materials of construction. More specifically, the composition and coatings formed therefrom of this invention are particularly useful in connection with protecting the precision surfaces, such as optical lenses, including but not limited to ophthalmic lenses, telescopic lenses, microscopic lenses and the like, which protection is desirably only of a temporary nature.

US Patent 5081174 to VanBuskirk et al discloses a formable, weldable, removable protective coating composition for use on metals, said coating comprising a combination of a base neutralized acid functional copolymer wax lubricant, and further comprising a removability enhancing means such as phosphoric acid as an additive to coating composition.
Patent Publication WO2009004684 in the name of Nihon Parkerizing Co.Ltd. teaches an aqueous fluid for treatment of zinc plated steel sheets. The composition comprises: a) ammonium zirconium carbonate, b) tetravalent vanadium compound, c) organophosphonic acid or its ammonium salt, d) anionic water dispersible acrylic resin and water. The solid content of anionic water dispersible acrylic resin is 1-60 mass% based on the total solid content of components. The steel sheet treated with aqueous fluid is excellent in corrosion resistance, alkali resistance, appearance, condensed dew resistance, and temporary coating.
US2002120056 to Denovus LLC describes an environmentally benign and water dispersible corrosion inhibitor which comprises: a) water dispersible polymer(s), water and additive(s). b) the polymer consists of vinyl acetate, vinyl acetate copolymers, vinyl acetate emulsion, polyvinyl acetate, or polyvinyl alcohol. The invention provides an environmentally benign and water dispersible corrosion inhibitor.

US 5292549 to Armco Inc. discloses a method of thin siloxane coating on steel plates. The process involves: a) washing the sheet with a mixture of silane and 0.1-1.0vol.% of cross linking agent, b) curing the silane below the decomposition temperature to form the siloxane film, the process is useful for suppressing the white rust on metalized, especially steel while awaiting processing or during transport to customer.
JP3115473 to Nippon Paints Co. Ltd. teaches water base anticorrosive paint for galvanized steel which comprises: a) water soluble, water-suspendible or water emulsifiable resin (pH of 8 to 9, from amony acrylic, vinyl ester, epoxy modified polyester resins), b) 0.1 2 vol% pigment (from chromium pigment and a calcium plumbate pigment) to give a water base anti corrosive paint for galvanized steel. The invention provides temporary white rust prevention during storage or transportation of galvanized steel products such as drinking water pipes, lightning poles, guard rails, steel towers and steel bridges.
US 2002026882 to Henkel Corporation discloses a temporary protective coating composition which comprises: a) water, b) 5-20% by weight polyvinyl alcohol, c) 0.05%-0.6% by weight Surfactant (perfluoroalkyl polyether non ionic surfactants, fluoroalipahtic polymeric ester non ionic surfactants, fluoroaliphatic sulfate surfactants,

fluoroaliphatic sulfonate surfactants, amine perfluoroalkyl sulfonate surfactants, alkoxylated phenol surfactants, and acetylenically unsaturated non surfactants), d) 0.1-5% by weight alkanolamine, e) 0.1-5% by weight corrosion inhibitor (alkanolamines, adducts of carboxylic acids and amines, and nitrogen containing heterocycles). It is used to protect the surface of metals articles from corrosion and contamination during the formation.
EP 162611 to Imperial Chemical Industries PLC provides an aqueous composition (an addition copolymer which is dissolved or dispersed in the aqueous liquid medium in the form of salt) for producing an alkali soluble temporary protective coating. The copolymer contains carboxyl groups to give an acid value of 25-150 mg KOH/g and comprises 2-20 wt % (meth)acrylamide, N-(1-8C alkyl) acrylamide, vinyl pyrollidone, vinyl pyridine or a monomer having a polyoxyethylene chain of molecular weight 100. The coating is applied 10-20 microns thick to give temporary protection to a surface liable to deteriorate on exposure to the atmosphere or to be damaged by abrasion.
PL 128054 to Instytut Mechaniki Precyzyjnej provides a temporary corrosion protection for ferrous metals containing: a) synthetic tanning agents 0.2-25, b) natural tanning extensions (especially from oak, mimosa or quebracho) 0.2-25, c) pyrogallol, resorcinol,

hydroquinone and/or ascorbic acid 0.5-15 d) aqueous butadiene styrene copolymer, methacrylic butadiene copolymer, and/or poly(vinylacetae) latexes containing acrylate esters, e) optionally styrene 5-82 parts. The composition provides non toxic, non flammable, coating composition.
JP 59059886 to Mitsubishi Heavy Ind. Ltd. provides a temporary rust preventive method and rust preventive for iron and steel materials including tubes. The solution is prepared by heating (>=30°C) an aqueous solution which contains: a) 0.5-3% sodium nitrite and potassium nitrite, b) 0.5-2% sodium carbonate or potassium carbonate, 0.05-0.5% gelatin. This invention is useful to form easily a temporary rust preventive film which is easily strippable.
JP 201181558 to Takeda Chemical Industries Ltd. provides a temporary protective coating composition which comprises: a) a copolymer emulsion obtained by reacting a monomer mixture comprising: (1) 1-60% wt. conjugate diene monomer (1,3-butadiene), (2) 40-99% wt. polymerizable monomer (alkyl(meta) acrylate or an aromatic vinyl compound of the carbon numbers 1-20 which is copolymerize with monomer. Coating composition forms a temporary protection film excellent in adhesion to coated plates or members even at low temperatures an removability in wide temperature range and such as high mechanical strength that is caused no breakage during removal.

JP 2269781 to Yushiro Chemical Industries discloses a process to manufacture water based acrylic polymer compositions for surface protection. Aqueous protecting composition comprises: a) copolymerizing alpha, beta-monoethylenic unsaturated acid, b) ester if methacrylic acid in an alcohol solvent containing surface active agent and then add volatile alkali and water at the same time while distilling out the alcohol. It is used as primary anti corrosion of automobile, vehicles and mechanical parts.
JP 10157003 to Sumitomo Metal Ind. Ltd. discloses a steel material coated with temporary rust preventive coating agent. The agent consists of a solvent and a resin based preventive material. The boiling point for 60-90% by weight of solvents contained in the agent is less than 150° Celsius. The solvent enables low temperature hardening and self-recovering property. The coating protects the steel material from damage during the storage and shipment until usage and also protects steel pipes reliability for reuse.
JP 62149386 to Nippon Steel Corp. discloses a temporary rust preventive treatment of metallic pipes. Method includes: metal tube is coated with UV curable paint after thinly coating with alkyl or acrylic resin rust preventive. UV paint is mainly composed of acrylic

acid or methacrylic acid derivatives used for temporary rust prevention of steel. UV irradiation energy is approximate 1000W.sec/m2 or more. The rust preventive is of a solvent type or is water soluble or water dispersible. This method improves the performance of UV curable paint.
JP 60197888 to Ikunaga Kastumi provides a method and a composition for temporarily preventing rusting of steel material. A composition consists of: 0.1-20 wt% zinc powder or mixture of zinc powder with zinc oxide powder is added to the abrasive material. A very small amount of zinc is stuck to the surface of the steel material to prevent temporarily the rusting of the steel material. The method is effective in temporary prevention of rust for iron and steel materials.
JP 55038939 to Mitsubishi Heavy Ind. Ltd. provides temporary rust preventive method for iron and steel material. Methods include: surface of the iron and steel material is applied with a thin film of hydrogen di-ammonium citrate is prepared and heated to about 80°C. The iron or steel material heated to about 50°C is immersed in the solution.

Currently articles are oiled for achieving the surface protection and corrosion resistant properties but some problems are associated with oiling process such as sticking, slipping and cost.
US Patent 5453459 to Roberts et al discloses a composition for providing a temporary coating to protect the surface of an article and a solvent free composition for rapidly removing the coating from the article. The invention also includes a method for protecting the surface of an article and a system for carrying out the process.
Accordingly, there is a need for the protective coating which can be quickly applied with little effort, is resistant to environmental damage and can be removed easily after weathering for extended period.
Objects of the Invetion
It is therefore an object of the invention to propose an anti-rust coating applicable to steel substrates for temporary protection of steel during transit storage.
Another object of the invention is to propose an anti-rust coating applicable to steel substrates for temporary protection of steel during transit storage, which eliminates the disadvantages of prior art oiling system for temporary rust prevention.

A still another object of the invention is to propose an anti-rust coating applicable to steel substrates for temporary protection of steel during transit storage, which allows an easy application process on steel substrates.
A further object of the invention is to propose an anti-rust coating applicable to steel substrates for temporary protection of steel during transit storage, which is removable from the coated surface in a simple manner.
Description of the invention
The present invention provides water based rust preventive coating which is expected to have high corrosion resistant properties during transit and storage. It is desirable and often necessary to protect the articles form environmental damages to preserve its smooth and shiny surface.
The inventive coating is effective in protecting the surfaces of various products by reducing additional handling damage taking place in the prior art protective method of oiling the steel surfaces post production.

The present invention provides aqueous based coating composition useful for forming temporary protective coatings, such as for use on precision surfaces. The coating compositions include: A silicate based solution, anti rust solution and a phosphate salt as inhibitor. Silicate based salt solution is in the range of about 35% up to less than 70% by volume of the total composition, anti rust solution is in the range of about 1 to 3% by volume of the total composition and a phosphate salt of 0.5 to 2.0% by weight based on the total weight of the composition. 30 to 65% by volume of aqueous roll coolant is mixed with coating composition during application.
The coating is easy to remove without the need of any aqueous or non aqueous washing solution. According to the invention, the coating is mixed with roll coolant for an easy application method and to replace the prior art oiling of components during shipment and storage.
Methodology: adapted by the inventors
a) Extensive literature survey on temporary rust preventive coating.
b) Preparation of coating.
c) Application of coating on the article.
d) Characterization of coating.
e) Optimization of coating formulation.

Experimentation
a) Preparation of sample: Metal articles were cut into small dimension of 5cm in length. Irregular edged and other metal fines were removed by debris removing. Finally the samples were drilled with through hole at one end and cleaned with jute cloth to provide dirt free metal article surface for coating.
b) Formulation of Coating: Temporary rust preventive coating described in present invention comprises base solution and an anti rust solution. This composition additionally comprises solid particles of phosphate based inhibitor. pH of the coating was 9 to 11.
c) Application of coating: Metal articles were dipped into the formulated coating solution for predetermined dip time and were cured at room temperature.

Results
Articles coated with formulated coating as described in this invention were exposed to Salt Spray Test (SST), Atmospheric test, Cyclic Corrosion Test (CCT), Electrochemical Impedance Spectroscopy (EIS), Tafel, Scanning Electron Microscopy (SEM), and X-Ray Diffraction (EDAX) for evaluation of coating performance.
a) Articles exposed in SST chamber for 200 hrs and 2-5% brown rust was associated with the surface of article.
b) Articles exposed in atmosphere lasted for more than 120 days without rusting.
c) CCT was conducted on the sample according to the standard cycle SAEJ2334 and were found to be unaffected with brown rust for 10 cycles.
d) EIS and Tafel tests conducted on the coated articles showed that coating composition has greater corrosion resistance and less corrosion rate after being exposed in corrosive media.

WE CLAIM
1. An anti-rust coating applicable to steel substrates for temporary protection of steel
during transit storage, comprising:
• a silicate based solution, anti rust solution and a phosphate salt as inhibitor.
• silicate based salt solution is in the range of about 35% up to less than 70% by volume of the total composition, wherein the anti rust solution is in the range of about 1 to 3% by volume of the total composition, wherein the phosphate salt of 0.5 to 2.0% by weight based on the total weight of the composition; and
wherein 30 to 65% by volume of aqueous roll coolant is mixed with coating
composition during application.
2. The coating composition as claimed in claim 1, wherein the coating composition
is mixed with the coolant before application on the substrate.

3. The coating composition as claimed in claim 1, wherein the coating is applied on the substrate in the form of a thin layer, and wherein the thickness of the coating is 4-10 microns.
4. The coating composition as claimed in claim 1, wherein the corrosion resistance property of the coating when coated on the substrate and heated to 100°C remains unaltered.
5. The coating composition as claimed in claim 1, which is applied on the substrate surface by means of spraying or dipping.
6. The coating composition as claimed in claim 1, wherein the coated substrate is tested after 48 hrs at room temperature to obtain desired corrosion resistance.
7. The coating composition as claimed in any of the preceding claims, wherein the coating after application on the substrate can be removed merely by abrasion with cloth.

8. An anti-rust coating applicable to steel substrates for temporary protection of steel during transit storage, substantially as herein described.
9. The coating composition as claimed in claim 1, wherein the composition is non inflammable.
10. The coating composition as claimed in claim 1, wherein the pH range of the composition is between 9 and 11

An anti-rust coating applicable to steel substrates for temporary protection of steel during transit storage, comprising: a silicate based solution, anti rust solution and a phosphate salt as inhibitor, silicate based salt solution is in the range of about 35% up to less than 70% by volume of the total composition, wherein the anti rust solution is in the range of about 1 to 3% by volume of the total composition, wherein the phosphate salt of 0.5 to 2.0% by weight based on the total weight of the composition; and wherein 30 to 65% by volume of aqueous roll coolant is mixed with coating composition during application.