FIELD OF INVENTION
The present invention relates to the preparation of smart coatings of conducting polymers which can be used for preventing corrosion of iron under hostile environmental conditions. The aim of the invention is to design conducting co-polymer composites by incorporating filler materials and suitably selecting a medium for polymerization sothat the resultant epoxy coatings can be used for prevention of corrosion in saline water conditions.
More particularly the invention relates to synthesis of conducting co-polymer by selecting specific co-monomer which on mixing with epoxies are powder coated, the corrosion inhibition response is observed which is the novelty of the invention.
BACKGROUND OF INVENTION
Conducting polymers have attracted immense importance because of their versatile processing applications. These polymers are reported as corrosion inhibitors for some active metals and alloys. The mechanism of corrosion protection by conducting polymers involves anodic protection of the underlying metal, by raising its potential to passive region. Polyanilines and polypyrrole are the most studied conducting polymers because of its environmental stability, biocompatibility, physical and electrical properties. Recently, polypyrrole and polyanilines are reported as effective material for corrosion protection purposes. Polypyrrole based anti corrosive coatings can be prepared either by chemical synthesis or it may be electrochemically deposited on the metal surface. Electrochemical deposition of polypyrrole coatings are reported to be carried out on steel substrates using aqueous media. These coatings show good adherence to metal surface and thickness of the coatings can be controlled precisely. Schaftinghen et.al. have reported that the surface per-treatment of steel surface prior to electrochemical deposition of polypyrrole coatings has strong influence on corrosion

protection performance of the coatings. However, mechanical integrity and thermal stability of these polymeric coatings in harsh climatic conditions are still questionable.
Following are the works done so far in the field of conductive polymers based anti corrosive coatings
US patent- 20080305341 A1: Process for Coating Metallic Surfaces With an Anti-Corrosive Coating.
The patent relates to coating of metallic surfaces with an anti corrosive coatings containing conductive polymers in particulate form with a binder. The conductive polymers used were polyphenylene, polyfuran, polyimidazole, polyphenanthrene, polypyrrole, polythiophene and polythiophenylene. The conductive polymers were doped with anti corrosive mobile anions say, ZrF62", Ce04 4~, Mn04 ", Mn04 2_, Mo04 2~, Mo04 4", V04 2", W04 2". The conductive polymer coats the metallic surface and is also dried. A second composition containing a binder system is then applied as a dispersion (solution, emulsion and/or suspension) to the precoated metallic surface and is dried and optionally also polymerized with conductive polymers charged with anti-corrosive mobile anions. The binders are pblycarbonate-polyurethane, polyester-polyurethane, styrene, styrene-vinyl acetate.vinyl acetate, vinyl ester and/or vinyl ether. The limitation of these coatings lie in the use of toxic mobile anions and the use of polymer first on the surface followed by coating with binders.
EP1542240 A2 (2005) & US7141184 B2 (2006) - Polymeric electrically conductive
composition containing zirconia for films and coatings with high wear A resistive composition for screen-printing onto a substrate to form a cured film. The resistive composition, based on total composition, has a) 5 -30 wt. % of polymer resin, b) 10-30 wt. % conductive particles selected from the group consisting of carbon black, graphite and mixtures thereof and c) 0.1-10 wt. % zirconia particles, wherein all of (a), (b), and (c) are dispersed in a 60-80 wt. % organic solvent. A cured resistive film composition is also disclosed.
US20090078153 A1 (2009) - Corrosion inhibiting pigment comprising nano reservoirs of corrosion inhibitor
A corrosion inhibiting pigment includes nanoscale reservoirs (nanoreservoirs) of corrosion inhibitor for active corrosion protection of metallic products and structures, wherein the nanoreservoirs include a polymer or polyelectrolyte shell which is sensitive to a specific trigger and capable of releasing the inhibitor after action of the trigger. An anti-corrosive coating with self-healing properties includes the pigment, methods for

preparing the pigment, in particular by layer-by-layer deposition, as well as methods of use of the pigment.
US Patent 6756123 B2: Anti-corrosion paint for steel with polyaniline.
Present patent relates an anticorrosion paint for preventing steel materials from corrosion by using polyaniline as an anticorrosion pigment. The anticorrosion paint has an excellent anticorrosion effect, long persistence of the anticorrosion effect, high durability and superior coating property controlling the anticorrosion effect, without using metal causing environmental pollution as an anticorrosion pigment, the present invention provides a coated steel substrate comprising an anticorrosion paint system, wherein the paint system comprise a primer coat paint layer and a top coat paint layer: a primer coat paint layer including 3 to 49 weight percent (wt %) of the polyaniline, 40 to 86 wt % of the matrix resin, 1 to 47 wt % of the additives and 10 to 56 wt % of the mixed solvent; and a top coat paint layer for protecting for protecting the primer coat paint layer and improving the anticorrosion effect, the top coat paint layer including 40 to 89 wt % of matrix resin, 5 to 54 wt % of colored pigment, 1 to 50 wt % of additives and 5 to 54 wt % of mixed solvent. Epoxy resin or acrylic urethane resin may be employed as the resins. Titanium oxide, iron oxide (reddish brown, yellow or black), phthalocyanine blue or phthalocyanine green, may be used as inorganic or organic pigments. Xylene, toluene, methyl isobutyl ketone, butyl acetate, ethyl acetate, cellosolve acetate, ethyl cellosolve, n-butanol, iso-butanol, iso-propylalcohol, methyl ethyl ketone, cyclohexanone, methanol or diacetone alcohol may be used as solvents. The anticorrosion paint plays a role in exerting persistently the excellent anticorrosion effect without causing environmental problem. Herein the polymer polyaniline used has been synthesized in HCI medium or H2S04 medium and authors claim to use the leucoemeraldine form. But a loading of higher concentration of polyaniline with higher concentration of dopant is a limiting factor for its practical application. Moreover these coatings does not show self healing characteristic.
CN 102702920 A: .A water dispersible polyaniline anti-corrosive coating and preparation method thereof Aqueous polyaniline anti-corrosive paint and preparation method thereof.
The present invention relates to development of polyaniline anti corrosive coatings to solve the problem of that the present polyaniline anti-corrosive coating causes environment pollution and harmful to human body. The invention claims a water dispersible polyaniline anti-corrosive coating is a green environmental friendly anticorrosion coating and it has excellent antiseptic property. The invention provides an aqueous polyaniline anti-corrosive paint and a preparation method thereof, belongs to

the technical field of paint, and is used for solving the problem that the traditional polyaniline anti-corrosive paint causes pollution to the environment and harms the human body. The paint comprises a component A and a component B, wherein the component A comprises of epoxy resin, aqueous film-forming co solvent, deionized water, polyaniline nano fiber powder, filler, non-ionic surfactant, defoaming agent, aqueous dispersant; and the component B comprises aqueous curing agent, deionized water and leveling agent. The aqueous polyaniline anti-corrosive paint is a green and environment-friendly type anti-corrosive paint and has an excellent anti-corrosive property. The polyaniline is showing anti corrosive property in the above invention and does not show self healing characteristic.
CN102101962 B: A polyaniline epoxy anticorrosive dope and preparation method thereof .
The invention claims a polyaniline epoxy anticorrosive dope and its preparation method comprises component a, Epoxy resin, mixed solvent, polyaniline nanometer composite material. Component b is comprised of amine firming agent, ethanol without water. The toluene and xylene the invention claims a n-butyl alcohol isobutyl alcohol and tertiary butyl alcohol the invention claims a mixed into mixing solvent the component a and b according to weight ratio of 1: 0.5-1.2 mixing and stirring 0.5-1 h can. Whole coating material system the mechanical property of the aging resistant performance corrosion resistant performance is improved obviously the metal surface passivation form a layer of compact stable oxidation film it prevents the metal is further oxidized. The polymer used in this patent do show anti corrosive property as claimed in patent but does not show self healing characteristic.
CN 102352179 A: Metal surface of the polypyrrole anti-corrosive coating layer preparation method of Preparation method of polypyrrole anticorrosion coating on metal surface.
The invention relates to a preparation method of a polypyrrole anticorrosion coating on the metal surface. The method is characterized in that: a monomolecular film of a pyrrole derivative with two functional groups is self-assembled on the metal material surface, one functional group pyrrole of the monomolecular film is polymerized with pyrrole, and an obtained polypyrrole film which is chemisorbed on the metal material surface and is not easy to peel has an anticorrosion effect. The method, which allows the film which is compacter than common synthesized polypyrrole films to be generated on the metal material surface, allows the penetration of corrosion ions to the coating to be effectively obstructed in a long term, the metal corrosion potential to be improved and the corrosion current to be reduced; and the preparative coating which has the advantages of high adhesion, uneasy peeling, and uneasy scratch because of

compactness allows the metal material corrosion to be avoided. The inventors claim the coating to be anticorrosive but the coating does not have the formulation as detailed in our patent application.
CN 101864239 B: A hyper-branched epoxy resin and the polypyrrole composite anticorrosive paint and preparation method thereof
The invention claims a hyper-branched epoxy resin and the polypyrrole composite anticorrosive paint and preparation method thereof. Hyper-branched epoxy resin and the polypyrrole composite anticorrosive coating material comprises the following substances a component: Hyper-branched epoxy resin 50 to 80 wt% pyrrole 3 to 50 wt% diluting agent d 0 to 20% by weight; Component b: Fecl3 20 wt % to 80 firming agent 10 wt% 70wt by diluting agent 1wt wt%; A and component b the weight ratio of 1-3 1; The raw materials according to a component b and its mixing proportion is simple it can be used in the 80 centigrade and solidifying hyper-branched epoxy resin and the polypyrrole composite anticorrosive paint. Prepared by this invention has anticorrosive coating has excellent antiseptic property and physical and mechanical property it is friendly to environment. The invention discloses a hyperbranched epoxy resin/polypyrrole composite anticorrosive paint and a preparation method thereof. The raw materials of the hyperbranched epoxy resin/polypyrrole composite anticorrosive paint comprise a component A and a component B, wherein the component A comprises 50-80 wt% of hyperbranched epoxy resin, 3-50 wt% of pyrrole and 0-20 wt% of diluent, the component B comprises 20-80 wt% of FeCI3, 10-70 wt% of curing agent and 1-10 wt% of diluent, and the weight ratio of the component A and the component B is (1-3):1. The hyperbranched epoxy resin/polypyrrole composite anticorrosive paint is prepared by simply mixing the component A and the component B according to the proportion and curing at 80 DEG C when in use. The anticorrosive paint prepared in the invention has excellent anticorrosive performance as well as physical and mechanical properties and is environment-friendly. The patent does not report the life of the coating under sever conditions.
EP 1723270 A2: Method of using intrinsically conductive polymers with inherent lubricating properties, and a composition having an intrinsically conductive polymer, for protecting metal surfaces from galling and corrosion
A method for protecting a metal surface from galling and corrosion includes a step of providing a protective dry film on the metal surface. The film includes a solid lubricant and a conducting polymer, the conducting polymer having lubricant properties and being capable of binding the solid lubricant to the metal surface. Threaded metal joint surfaces coated with the film are capable of resisting galling under high pressure and

high torque conditions, even after several fastening and unfastening operations or over a long period of time. Protection from corrosion is also provided by the film. The method and film are economical in that only a single layer of protective compound need be applied in order to provide meti>l surfaces with both lubrication and protection against corrosion, and problems such as removal or leakage, which are associated with protective compounds that u$e oils, are avoided. Additionally, the dry film is advantageous because it does not contain heavy metals that are harmful to the environment. The patent does not report how the coating of conducting polymer with lubricant will behave in hazardous toxic conditions and does not show any smart action.
EP 1779392 BY. Pvoreas tor crcp&vg *•'&& partitas, »«tth cwductwfc VM^WM^
A process is disclosed for coating fine particles, in which the feed mixture contains: at least one monomer and/or at least one oligomer selected from monomers and/or oligomers of aromatic compounds and/or unsaturated hydrocarbon compounds suitable for forming an electroconductive oligomer, polymer, copolymer, block copolymer or graft copolymer; at least one type of anions which (1) are and/or can be incorporated as doping ions into the structure of the conductive polymer; (2) can be discharged from said structure in the event of a potential fall of the conductive polymer (reduction); and (3) can have an anti-corrosive effect in the presence of a metallic surface; at least one type of particles; if necessary, at least one oxidising agent and water and/or at least another solvent. A coating is formed from the feed mixture on the particle surface, the feed mixture being converted by oxidation into a conductive polymer in the presence of at least one type of mobile anti-corrosive anions. Alternatively, the fine particles are coated with a product mixture that contains a conductive polymer. The patent application does not speak about the suitability of coatings on metal surface in critical conditions and its mechanism.
US 6762238 B1: Water-borne polymeric complex and anti-corrosive composition. A coating composition which contains a polymeric complex between polyaniline and a polymeric ion. In addition to the said polymeric complex, the composition contains a water-dispersable binder. The composition is useful as a water-borne paint to be applied onto a metal substrate electrophoretically or non-electrophoretically. The limitation of this patent application is the use of water borne polymeric complex which may lose its adherence to the metal surface under vigorous salt spray conditions.
US 8298350 B2: Chromium-free conversion coating
The patent describes preparation of chromium-free conversion coating by the addition of inorganic salts to dispersions of conducting polymers which are then exposed to alloys of aluminum or other metals. Advantageously, the performance of the coating is

comparable to that of known Cr (chromium)-based methods for a number of aluminum alloys having particular significance in the manufacture of aircraft. Herein patent a conversion coating composition for treatment of metallic surfaces, the conversion coating composition consisting of a conducting polymer dispersion consisting of a conducting polymer selected from the group consisting of polyaniline (PANI), polyethylenedioxythiophene (PEDOT) and polypyrrole (PPY) is used along with using different salt compositions like K2ZrF6. The limitation of the patent is the specific application to Aluminum and its alloys but does not provide smart action under vigrous conditions.
US 5993695 A: Aqueous coating dispersion, process for the preparation thereof and use thereof in anticorrosive paint.
The invention relates to an aqueous coating dispersion comprising at least electrically conductive particles, which particles comprise at least a first binder, a conductive polymer and a non-ionic stabilizer, characterized in that the coating dispersion contains 50 to 99 wt. %, relative to the total amount of solids present, of a second binder, which second binder does not form part of the electrically conductive particles. The invention also relates to a process for the preparation of the aqueous coating dispersion and to the use thereof in an anticorrosive paint, to the anticorrosive paint based on the aqueous coating dispersion according to the invention and to the metals protected herewith. The limitation of this patent is the use of aqueous coatings of polymers which is dispersed in polyurethane in water which is stabilized by incorporating methoxypolyethylene glycol chains. These were applied to a standard steel plate with the aid of a coating knife, after which it was cured for 10 minutes at 80° C. and conditioned for 1 week. The process tells about corrosion prevention but does not have any self healing mechanism.
R. J. Racicot and S. C. Yang describe and compare the corrosion resistance performance of a polyaniline based conductive polymer coating versus a chromate conversion coating on two aluminum alloys in a paper entitled, "CORROSION PROTECTION COMPARISON OF A CHROMATE CONVERSION COATING TO A NOVEL CONDUCTIVE POLYMER COATING ON ALUMINUM ALLOYS", which was presented at CORROSION 97, paper 531, pp. 531/1-531/7, Houston, Tex., 1997. As disclosed by the authors, the double strand polyaniline exhibited limited corrosion protection for aluminum alloys AA2024-T3 and AA7075-T6 in salt-spray and salt and acid immersion tests.
Objective of the Invention:

The main objective of the present invention is to synthesis conjugated copolymers embedded with filler materials like zirconium oxide and silica oxide and synthesized in a specific medium. These formulation when embedded with epoxy and powder coated on mild steel surfaces acts as barrier for corrosion and gives a corrosion inhibition efficiency of the order of > 99 % when exposed to highly saline conditions like 3.5 % NaCI.
Summary of the invention:
Accordingly, the present invention provides a process of synthesizing conducting polymers on filler materials like zirconium oxide and silica in a specific medium of inorganic/organic acid medium consisting of phosphoric acid and the like. The method comprising:
(a) Synthesis of conducting co-polymer Poly (aniline co pentafluoroaniline) and the like on zirconium oxide and silica particles by oxidative polymerization in the presence of phosphoric acid and the like.
(b) Mixing the copolymer in different ratios of epoxy and doing powder coating on mild steel substrates by powder coating technique.
(c) Testing the copolymer coated mild steel surfaces under hostile conditions of 3.5 %,NaCI
(d) Checking the performance of the coating by Tafel plots and polarization studies
(e) Testing the coating under accelerated conditions as per ASTM standards
In one embodiment of the invention, the monomers chosen for study are aniline and
pentafluoroaniline
In another embodiment of the invention, the filler material taken for polymerization is
selected from zirconium oxide, silica and the like.
In another embodiment of the invention, the medium of polymerization is chosen from
phosphoric acid and the like.
In another embodiment of the invention, the oxidant chosen for above study was
ammonium persulphate or potassium persulphate, ferric chloride and the like.

In another embodiment of the invention, the temperature of the polymerization condition
was kept between 0 to 5°C.
In further embodiment of the invention, the filler to monomer ratio was kept between 1 to
15%.
In another embodiment of the invention, oxidant to monomer ratio was kept between 0.1
mole to 0.2 mole.
In another embodiment of the invention, the medium for the study was phosphoric acid
whose ratio to monomer was kept between 0.1 to 0.5 mole.
In one embodiment of the invention, the polymerization reaction time was kept between
2-6 hours.
In another embodiment of the invention, the powder obtained after filtration was dried in
vacuum oven at 50-60°C.
In another embodiment of the invention, polymer obtained after drying was mixed with
epoxy in the range of 1 to 6 %.
In another embodiment of the invention, the mild steel surfaces was coated with epoxy
mixed with polymers by powder coating technique.
In another embodiment of the invention, the powder coated samples were kept in oven
at140-160°C.
In another embodiment of the invention, the powder epoxy mild steel samples were
tested by Tafel plots in saline water(3.5 % NaCI) and under accelerated conditions as
per ASTM standards.
DESCRIPTION OF DRAWINGS
In the drawings accompanying this specification
Fig. 1: Schematic of the synthesis of poly(aniline-co-Penta fiuoro aniline/ ZrC"2 nano composite by chemical oxidative polymerization process
Fig. 2: Tafel plots of epoxy coated mild steel and epoxy with copolymer (Poly(AN-co-PFA) Zr02 nanocomposite coated mild steel substrate exposed to 3.5 wt.% NaCI solution for 1 day at room temperaturein 3.5% NaCI solution

Fig. 3: Tafel plots of epoxy coated mild steel and epoxy with copolymer (Poly(AN-co-PFA) Zr02 nanocomposite coated mild steel substrate exposed to 3.5 wt.% NaCl solution for 10 days at room temperature in 3.5% NaCl solution
Fig. 4: Tafel plots of epoxy coated mild steel and epoxy with copolymer (Poly(AN-co-PFA) Zr02 nanocomposite coated mild steel substrate exposed to 3.5 wt.% NaCl solution for 30 day at room temperaturein 3.5% NaCl solution
Fig. 5: Photographs of Composite Epoxy Coated Panels on 1st Day after exposure to 5.0 % NaCl in Salt Spray Chamber
.Fig. 6: Photographs of Copolymer composite panels exposed to Salt Spray Chamber for 80 days in 5.0 % NaCl as per ASTM Bl 17 (a) only epoxy coated mild steel panel (b) 1 % composite coated mild steel panel (c) 2 % composite coated panel (d) 3 % composite coated panel (e) 4 % composite coated panel and (f) 5 % epoxy coated mild steel panel
Fig. 7: Photographs of mild steel panels coated with epoxy after 1 day, 20 days and 45 days exposure to 5.0 & NaCl in Salt Spray Chamber as per ASTM Standards
Fig. 8: Bend Test Studies of Composites panels
Fig 9: SEM micrographs showing morphology of (a) Zr02 nanoparticles, (b) poly (aniline-pfluoroaniline)/Zr02 composite. Zr02 particles embedded inside the polymer matrix are visible in the micrograph.
Fig. 10: Taber Abrasion Test Results of poly(AN-co-PFA)/Zr02 -epoxy coated panel
Table 1. Different electrochemical parameters obtained from Tafel extrapolation method for the specimens exposed to 3.5% NaCl solution

We claim:
1. A process for synthesizing conducting copolymers of aniline and
pentafluoroaniline in the presence of filler materials like zirconium oxide or silica
or mica in the presence of suitable medium like o-phosphoric acid and the like.
The method comprises:
(a) Synthesizing polyanilines in the presence of specific filler material like zirconium oxide/silica/mica
(b) Mixing the polymer in different ratios of epoxy and doing powder coating on mild
steel substrates by powder coating technique.
(c) testing the polymer coated mild steel surfaces under hostile conditions of 3.5 % NaCI
(d) Checking the performance of the coating by Tafel plots and polarization studies
(e) Testing the coating under accelerated conditions as per ASTM standards

2. A process as claimed in claim 1 wherein the polymer chosen for coating was selected from copolymers of aniline and pentafluoroaniline and the like
3. A process as claimed in claim 1-2, wherein the medium of polymerization was chosen from o-phosphoric acid and the like.
4. A process as claimed in claims 1-3, wherein the oxidant for polymerization was chosen from ammonium persulphate, ferric chloride, ferric phosphoate and the like
5. A process as claimed in claims 1-4, wherein monomer aniline & [entafluoroaniline and the like are first encapsulated on zirconium oxide/silica/mica particles and then polymerization was initiated by oxidant in the temperature range of 0-5°C +1.0°C.
6. A process as claimed in claims 1-5, wherein the epoxy for the powder coating was thoroughly mixed with polymer in 1 to 6 wt. % ratio.
7. A process as claimed in claims 1 to 6, wherein epoxy mixed with polymer was powder coated on mild steel substrates using powder coating technique.
8. A process as claimed in claims 1-7, wherein the coated samples were kept in the oven at 140-160°C for 2-4 hours.
9. A process as claimed in claims 1-8, wherein the epoxy:polymer coated samples were evaluated by Tafel Plot methods and by salt spray technique in 3.5 % NaCI.