2. FIELD OF INVENTION
This innovation relates to the preparation of nano calcium carbonate incorporated in conducting polymer matrix for finding its application in the protection of iron and mild steel in marine environment. Our innovation describes a process for the preparation of intelligent coatings of conjugated polymers incorporated with nano calcium carbonate which can be used for the protection of corrosion under sever corrosive conditions. Main objective of the innovation is to design conjugated polymer blend in a suitable polymerization medium so that these blends when incorporated in paint formulations can be used for the protection of iron and mild steel under corrosive conditions. Our process doesn’t use toxic heavy elements or toxic chromates in their designing and that makes our innovation quite innovative. Intelligent coatings, refer to coating systems capable of sensing the generation of corrosive environments, and self-responding to corrosion occurrence in demand. In this innovation, an intelligent coating technology based on conjugated polymer host pre-loaded with nano calcium carbonate - in an epoxy host coating was developed for effective corrosion protection of mild steel.

3. BACKGROUND OF INVENTION

Corrosion protection of metals and mild steel & iron in particular is conventionally carried out by various techniques like protective primers and coats, chromate layers, sacrificial zinc layers and paints. However, common paints don’t provide enough protection. Once on these metal surfaces coated with paints gets defects or scratch is formed, there is rapid deterioration of metal surface and corrosion starts taking place. Conventional paints contain lead, cadmium and even chomating of surfaces is carried out and these paints and processes have to be phased out. Even volatile organic compounds emission from the paints has to be low as natural resources have to be preserved.

Almost all of the organic coatings are susceptible to cracks formed deep within the structure because of changes in the mechanical properties of the coatings during their service life. The cracks propagate and expose the substrate to corrosive environments, finally leading to the failure of the coatings. Researchers all over the world are making efforts to find proper methods to improve the anticorrosion properties of the protective coatings. Intelligent coatings technology has evolved from a coating with a specialized resin, pigment, or other material that can respond to an environmental stimulus and react to it. This response can be used in various ways to protect materials from corrosion and other types of damage. There are two basic mechanisms by which intelligent coatings provide corrosion protection: i.e., blocking barrier and chemical inhibition. Organic coatings can retard corrosion through a barrier mechanism, which is achieved via a coating that effectively isolates the substrate from corrosive elements such as moisture, oxygen and ionic species that can react with the substrate. Organic coating with intelligent properties means that this coating can allows release of the inhibiting species into the aqueous environment present on the metal substrate to retard corrosion via barrier, chemical inhibition or sacrificial mechanism.
Conjugated polymers are a new class of materials with interesting potential applications in number of advanced technologies like EMI shielding, ESD, super capacitors and corrosion inhibition coatings. Deliberate modifications in the chemical structure and designing copolymers by copolymerizing two different monomers can lead to the formation of conjugated backbone with p & n characteristics which can be tailormade for the specific applications. Conjugated polymer technology will be useful to many industrial sectors due to their ability to fabricate and design new shapes and wide range of possible engineering solutions
Ordinary calcium carbonate is widely used in fields such as plastics, rubber, papermaking, printing ink, coating already as a kind of filler, its major function is to reduce product cost and improve product performance. In recent years the nano-calcium carbonate of being paid close attention to deeply because of it has nano level granularity, when using in above-mentioned field, can give product other functions again, for example changes product rheology, improves intensity, increases toughness etc. But, compare with ordinary calcium carbonate, undressed nano-calcium carbonate, be applied to exist in the organic medium two shortcomings, the first is in the thermodynamic instability state because of the particle surface energy height, and particle itself is very easily assembled agglomerating, be difficult to make its particle in applicating medium, to reach nano level granularity with conventional dispersing method, thereby influenced effect; It two is because of its surface hydrophilic oleophobic, is difficult to combine with organic medium, is evenly distributed in the organic medium, not only fails to realize its intended function. Cause original degradation on the contrary. So, usually adopt properties-correcting agent that Nano particles of calcium carbonate is carried out surface modification, its surface energy is reduced, improve its surperficial lipophilicity simultaneously. Adopt titanic acid ester, silane coupling agent, lipid acid etc. as properties-correcting agent at present, it is added to carries out the surface in the nano-calcium carbonate water slurry and coat, make nano-calcium carbonate can reach the good distribution effect by routine dispersion means, but the nano-calcium carbonate after this modification, be used for coating system and fail to give coating other functions, sometimes even can reduce some performance of coating. The intelligent coatings can sense the environment and provide an appropriate response. It can control at an early stage to prevent further corrosion and provide coatings with reliable corrosion protection properties during long service life.

Calcium carbonate is one of the most commonly used additives in the paper, paint and plastics industries. While naturally occurring ground calcium carbonate (GCC) is usually used as a filler in many applications, synthetically manufactured precipitated calcium carbonate (PCC) may be tailor-made with respect to its morphology and particle size allowing these materials to fulfil additional functions. However, commonly known PCC production processes including the steps of calcining crude calcium carbonate, slaking it with water, and subsequently precipitate calcium carbonate by passing carbon dioxide through the resulting calcium hydroxide suspension, need high quality starting materials as there is no reasonable method to separate impurities from the raw material during this process. Calcium carbonate is widely used in the production field of plastics, rubber, adhesives, sealants, paper, inks, cosmetics and medicine. By modifying the surface of calcium carbonate nanometric particles, it is possible to control the rheological and mechanical properties of the materials. For example, PVC with calcium carbonate has an extended glass transition temperature, an excellent heat stability, a low viscosity and good tensile strength.

There are numerous approaches in the prior art to produce calcium carbonate having certain properties such as high purity, most of which however are focussing on this one property only, whereas the processes do not allow to fully control also other properties such as crystal shape, particle size etc., or high amounts of rejects are often produced by such known processes. In Chinese patent application No. 1757597, a process for preparing porous superfine calcium carbonate is described. This is achieved by preparing an aqueous solution of calcium chloride, as well as, separately, an aqueous solution of ammonium hydrogen carbonate and carbon dioxide, and reacting these solutions in a colliding reaction, being a rather complex reaction in practise, while controlling flow and temperature, resulting in the formation of porous superfine precipitated calcium carbonate having a high specific surface area. The mother liquid containing ammonium chloride is reused for solving calcium chloride therein, but the ammonium chloride is not used as a reactant as such. Thus, the process according to CN 1757597 starts with a high-quality starting material, wherein high porosity and high fineness particularly are achieved by the specific type of colliding reaction. The reject, inter alia ammonium chloride solution, is not reused as a reactant, but simply as a solvent, which will lead to an enrichment of ammonium carbonate not only in the solution, but also in the final product, until it is separated. No mention is made in this document as to obtaining precipitated calcium carbonate having a high purity and defined crystal structure.

Application ID 1539/MUM/2012 (2012-05-21) – Synthesis of Corrosion Inhibiting nano pigment comprising of nano container for corrosion inhibitive coating; Sameer Arvind Kapole, Sonawane Shirish Hari, Kulkarni Ravindra Dattatrya, Aniruddha Bhalchandra Pandit, Bharat Apparao Bhanvase, Dipak Vitthal Pinjari, Parag R. Gogate

The main objective of the invention is to study the ultrasound assisted synthesis of nano container by LbL method and its application in anticorrosive coatings. One of the objectives of an invention is use corrosion inhibitor in the preparation of nanocontainer by LbL method under ultrasonic irradiation. Synthesis of nano container particles, preparation of nanocontainer polyamide composite by in-situ method, preparation of 2K epoxy-polyamide coatings, application of coating on mild steel substrate, evaluation of the coated film for corrosion inhibition properties. In present investigation blend of Iron oxide and sodium zinc molybdate particles are taken in which Sodium zinc molybdate has been recommended as non-toxic anticorrosive pigment for marine coatings as molybdate compounds possess a low toxicity as compared to chromate/lead salts. Selection of sodium zinc molybdate pigment has been made due to the following reasons (1) zinc element gives the anti-corrosion performance by sacrificial mechanism, since it is more electronegative than substrate (mostly Fe) and (2) molybdate group partially dissolves in water and forms adsorbed inhibitive layer on the metal surface. While nano size of Iron oxide pigments has a porous structure which allows the adsorption of sodium zinc molybdate and results into coherent blend. The corrosion inhibitor has been incorporated in the nanocontainer by LbL deposition of corrosion inhibitor and polyelectrolyte layers. The common mechanism of such reservoir-based approaches is the slow release of inhibitor triggered by corrosion process. In this case, storage of inhibitor in nanoscale reservoirs with average dimension in the range of 100 to 1000 nm comprising a LBL polyelectrolyte shells. Inhibitor perform in coating and provide intelligent release of inhibitor due to permeability of reservoir when exposing it to external stimulus such as pH change, ionic strength, humidity, light temperature, chloride salt attack.

US 9233394 B2 (11.01.2016) – Hydrophobic-core microcapsule and their formation, Calle Luz M, Li Wenyan, Buhrow Jerry W & Jolley Scott T, Assignee: National Aeronautics and Space Administration Nasa

Hydrophobic-core microcapsules and methods of their formation are provided. A hydrophobic-core microcapsule may include a shell that encapsulates a hydrophobic substance with a core substance, such as dye, corrosion indicator, corrosion inhibitor, and/or healing agent, dissolved or dispersed therein. The hydrophobic-core microcapsules may be formed from an emulsion having hydrophobic-phase droplets, e.g., containing the core substance and shell-forming compound, dispersed in a hydrophilic phase. The shells of the microcapsules may be capable of being broken down in response to being contacted by an alkali, e.g., produced during corrosion, contacting the shell. method of forming hydrophobic-core microcapsules comprising: forming a hydrophobic phase including a pre-polymer or monomer, a cross-linking agent, at least one active substance, wherein said at least one active substance is a corrosion indicator, a corrosion inhibitor, or combination thereof, an optional co-solvent, and a hydrophobic substance; forming a hydrophilic phase; mixing the hydrophobic phase with the hydrophilic phase to create and disperse droplets of the hydrophobic phase within the hydrophilic phase to form an emulsion; initiating a reaction at an interface of the hydrophilic phase and the hydrophobic phase to form a solid shell encapsulating the hydrophobic phase forming hydrophobic-core microcapsules, wherein said solid shell includes a shell wall comprising a compound having one or more chemical bonds that are broken down when contacted with an alkali produced during a corrosion reaction causing the release of the hydrophobic phase, wherein said alkali has a pH above about 8.

US10011723 (03 July 2018) - Anti-corrosion coatings – Inventor – Pagona Papakonstantaninou, University of Ulster;

A coating comprising silicon-doped graphene layers wherein the graphene is in the form of horizontally-aligned graphene nanosheets. A coating comprising silicon-doped graphene layers wherein the graphene is in the form of horizontally-aligned graphene nanosheets, and wherein the silicon content of the silicon-doped graphene is in the range 2 to 60 at %. The present invention relates to protective coatings, specifically to protective silicon-doped graphene coatings for use on metals, their production and uses. The invention also relates to a method of inhibiting corrosion comprising the formation of said coatings and the use of said coatings in the inhibition of corrosion, particularly in the reduction of oxidative corrosion.

WO1995003136A1 (February 2, 1995) - Corrosion inhibiting multilayer coating - Patrick John Kinlen, David Charles Silverman, Christopher John Hardiman

Corrosion resistant metal laminates having, in series, a metal layer, a non-metal conductive layer and a non-conducting layer. The non-metal conductive layer comprises inherently conducting polymer, e.g., polyaniline or polypyrrole, in a non-conducting matrix, e.g., an inorganic matrix such as a silicate, a thermoplastic polymer matrix such as a polyolefin or a vinyl polymer or a thermoset polymer matrix such an epoxy, a polyurethane or a polyimide. Preferred intrinsically conductive polymers include sulfonic acid doped polyaniline. The inherently conducting polymer-containing matrix is preferably strongly adhesive to metal and provides enhanced corrosion resistance to the metal in a variety of corrosive environments such as acidic, alkaline, and salt environments. This invention provides corrosion resistant metal laminates and methods of providing such laminates •employing coatings of a mixture of inherently conducting polymer in a non-conducting matrix.

WO2013083293A1, June 13, 2013 - Anti-corrosion system for steel, Inventor: Tapan Kumar Rout, Anil Vilas Gaikwad, Theo Dingemans, Mikhail Zheludkevich, Joao TEDIM, Kiryl YASAKAU;

The present invention relates to a method of manufacturing a coated steel substrate which comprises the steps of: (i) providing a steel substrate; (ii) preparing a first coating mixture comprising nanocontainers with nanoscale corrosion inhibitors contained therein; (iii) preparing a second coating mixture comprising a curable organic component; (iv) combining the first coating mixture and the second coating mixture; (v) applying the combined mixture on the steel substrate; (vi) curing the combined mixture so as to produce a dense network structure of the coating for barrier and active corrosion protection of the steel substrate. Method of manufacturing a coated steel substrate according to any one of the preceding claims wherein the nanoscale corrosion inhibitors comprise anionic corrosion inhibitors and cationic corrosion inhibitors, preferably one or more of Sodium molybdate Na2Mo04, Cerium molybdate Ce2(MoO4)3, Cerium nitrate Ce(NO3)3, Calcium nitrate Ca(N03)2, Zinc sulfate ZnSO4, Sodium tungstate NaW03, Sodium phosphomolybdate hydrate, Na3Mo12O40P, Sodium phosphate Na3PO4, Sodium hydrophosphate Na2HPO4, Sodium dihydrophosphate NaH2PO4, Sodium carbonate Na2CO3, sodium polyphosphate NaPO3x, Sodium Gluconate, 2-Mercaptobenzothiazole, Benzimidazole, Quinaldic acid, Sodium Citrate, Glycine, 8-hydroxyquinoline, Sodium Salycilate, Sodium benzoate, 1- hydroxy ethylidene diphosphonic acid (Etidronic acid) , Nitrilo-tris-phosphonic acid , N,N dimethylamine , Di-azo compounds , Cu-thalocyanine, dyes tartrazine (TZ)). The present invention relates to a method of manufacturing a coated steel substrate, the coated steel substrate thus produced and to the use of the coated substrate in automotive, building or construction applications.

US Patent 6054514, April 25, 2000; Assignee: Americhem, Inc. (Cuyahoga Falls, OH), Inventor: Vaman G. Kulkarni (Charlotte, NC)

A corrosion inhibiting paint composition comprises from about 1 to 20 parts by weight of a corrosion inhibiting additive mixture comprising 1 to 25 parts by weight of an organic sulfonic acid in a mixture of 75 to 99 parts by weight of butyrolactone; from about 10 to 99 parts by weight of film forming polymer; and from about 0 to 89 parts by weight of a liquid medium selected from the group consisting of water, organic solvents for the film forming polymer and mixtures thereof. Another corrosion inhibiting paint composition comprises from about 1 to 20 parts by weight of a corrosion inhibiting additive mixture comprising 1 to 25 parts by weight of an organic sulfonic acid in a mixture of 75 to 99 parts by weight of butyrolactone; from about 10 to 98.5 parts by weight of film forming polymer; from about 0.5 to 20 parts of an intrinsically conductive polymer; and from about 0 to 89 parts of liquid medium selected from the group consisting of water and organic solvents for the film forming polymer and mixtures thereof. Metal substrates containing a coating composition comprise an organic film forming matrix and an additive mixture comprising organic sulfonic acid and butyrolactone. A method for imparting corrosion resistance to metal substrates comprises providing a layer of a coating composition on at least one surface of the substrate, formed from an organic film forming matrix and an additive mixture comprising an organic sulfonic acid and butyrolactone. The present invention relates to corrosion protection of metals. Specifically, the invention relates to additives that enhance the corrosion protection offered by conventional organic coatings. More specifically, the invention relates to additives that enhance the corrosion protection of conductive polymer coatings. Metal substrates, protected from corrosion are provided based upon the use of coating compositions containing additives according to the present invention. A method for imparting corrosion protection to metal substrates is also provided.

Lu et al., (Lu. W. K. Elsenbaumer. R. L., and B. Wessling, Synthetic Metals, 71(1995) 2163, and Wei-Kang Lu, Sanjoy Basak and Ronald L. Elsenbaumer. "Corrosion Inhibition of Metals by Conductive Polymers" HANDBOOK OF CONDUCTING POLYMERS, edited by Terje A. Skotheim, Ronald L. Elsenbaumer and John R. Renyolds, Marcell Dekker (1998), reported corrosion protection of mild steel in acidic and saline atmosphere using neutral and doped polyaniline coatings, with a epoxy top coat. Neutral polyaniline was applied from NMP solutions, which were further doped with p-toluene sulfonic acid. Both the neutral and doped polyanilines showed corrosion protection. Corrosion protection provided by doped polyaniline was more significant in acid conditions than saline conditions. Very recently, Sitaram et al (S. P. Sitaram, J. O. Stoffer and T. J. O'Keefe, Journal of Coatings Technology, 69(866), 1997,65) have reported corrosion protection of untreated steel using Versicon, a doped polyaniline, neutral polyaniline and PANDA, a soluble form of polyaniline manufactured by Monsanto. They reported PANDA exhibited significant improvement in corrosion protection, when used as a base coat, with a conventional top coat. It was interesting to note that both Versicon and PANDA did not exhibit significant protection, when formulated in to conventional coatings such as epoxy or acrylics. They concluded that polyaniline/PANDA does not function as a pigment.

Smart Coatings - Plating & Surface Finishing - October 2007, 24-29; Eric W. Brooman, Ph.D. Consultant Materials & Processes Professional Services (M&PPS)

Smart coatings do not have any innate “intelligence,” but they can, and do respond in predictable ways to changes in the environment, providing functionality that is “well beyond simple protection or decoration.” In fact, the definition used in this reference1 is that “materials, which are capable of adapting dynamically their properties to an external stimulus, are called responsive, or smart.” Smart coatings have been devised for corrosion prevention, detection and control. In the area of detection, agar-based gels containing pH indicators, such as phenolphthalein, have been used as temporary coatings to identify areas of corrosion on the surfaces of original components and equipment, and on the surfaces of components or equipment that have been prepared for maintenance, overhaul or repair. Such indicators also have been proposed for use in paints, wherein the indicating chemicals are microencapsulated and react with the change in chemistry when localized corrosion occurs. With respect to control and prevention, smart coatings include those that contain phosphate or chelating chemicals to convert the rust formed on steel structures, especially cruise ships, to control the amount of rust formation and provide an opaque film that “aids in color retention.” This technology has been adapted by the U.S. Navy for use on their ships. Other examples include the previously mentioned use of microencapsulated inhibitors, and the use of “release on-demand” inhibitors attached to nanoparticles, or in nano porous additives to form stable barrier films in damaged coatings. Both approaches were reported as being promising. Other researchers have tried a similar approach by incorporating silicon or cerium oxide nanoparticles into silane coatings on galvanized steel substrates. The results obtained with CeO2 particles were the most encouraging. Filiform corrosion on aluminum alloy substrates can be controlled with the use of hydrotalcite-like anion exchange additives because they are effective halogen scavengers and also neutralize the aqueous acid formed at the head of the filiform structures. Conductive polymers, such as polyaniline, containing anionic inhibitors also have been investigated to prevent corrosion on AA2024- T3 aluminum alloy surfaces. Here the mechanism is different in that damage exposing the substrate metal polarizes the polyaniline film and releases the inhibitor, allowing a protective film to form. Similar work has been done at the University of Sao Paulo for copper, silver and iron substrate materials. The effectiveness of the passivating film that is formed depends on the relative galvanic activity (driving force) of the substrate metal.

US-9816189-B2 (14.11.2017)-Corrosion inhibiting compositions and coatings including The Same, Fitz Todd Andrew, Berg Mariko Elaine, Assignee: Honda Motor Co Ltd. (JP)

A corrosion inhibiting composition includes a first plurality of carriers and a second plurality of carriers. The first plurality of carriers has a first carrier body which encapsulates a film-forming compound. The second plurality of carriers has a second carrier body encapsulates a corrosion inhibitor. Each of the first and second carrier bodies is formed of a degradable material. Coatings and methods for inhibiting corrosion on a metal substrate are also described herein. In yet another embodiment, a method for inhibiting corrosion on a metal substrate includes applying a coating to a metal substrate. The coating includes a coating base and a corrosion inhibiting composition. The coating base includes an organic matrix. The corrosion inhibiting composition is dispersed in the coating base. The corrosion inhibiting composition includes a first plurality of carriers and a second plurality of carriers. Each of the first plurality of carriers includes a first carrier body and a film-forming compound. The first carrier body encapsulates the film-forming compound. The first carrier body has a first average diameter and is formed of a first degradable material. Each second plurality of carriers includes a second carrier body and a corrosion inhibitor. The second carrier body encapsulates the corrosion inhibitor. The second carrier body is formed of a second degradable material and has an average diameter that is larger than the first average diameter.

277928 – (9th December 2016) CONDUCTING POLYMER PAINTS AND COATING COMPOSITION FOR THE CORROSION PROTECTION OF IRON, Dhawan Sundeep Kumar, Sadagopan Sathiyanarayanan, Sulthan Syed Azim, Saini Parveen, S Rahdakrishnan
A process for the preparation of conducting polymer acrylic resin which can be used by applying to the surface of steel a coating of acrylic paint containing conducting polymer as pigments along with other constituents. The invention relates to synthesis of copolymer of aniline and substituted aniline comprising of sec. butyl aniline, o-phenetidine, o-ethyl aniline and o-toluidine. The copolymer of aniline and substituted aniline are synthesized in the presence of acid free environment and are embedded on fillers titanium oxide and are mixed with resin in appropriate ratio. In the present case a coating of copolymer mixed with other materials acrylic resin which is applied on the surface for the corrosion protection of iron and mild steel against hostile environment like saline water comprising NaCI, MgCl2, BaCl2 and so on. The main objective of the present invention is to provide a process for the
preparation of conducting polymer coating composition useful for corrosion
protection of iron and mild steel, which obviates the drawbacks as, mentioned
above. Another objective of the present invention is to provide a process for the
preparation of conducting polymer coating composition in acid free condition.
Another objective of the present invention is to provide a process for the
preparation of copolymer of aniline and substituted aniline synthesized in the
absence of acidic conditions which can be useful for the prevention of corrosion
of iron and mild steel in hostile saline atmosphere. Yet another object of the present invention is to provide a single coat of conducting polymer coating for the anti-corrosive coating.

US Patent 5658649, (19.08.1997); Corrosion resistant coating, Wrobleski, D A; Benicewicz, B C; Thompson, K G; Bryan, C J; USDOE, Washington, DC (United States)

A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

Development of a smart coating based on hollow nanoparticles for corrosion detection and protection, Pierre Loison, HAL Id: tel-02475624 https://tel.archives-ouvertes.fr/tel-02475624 Submitted on 12 Feb 2020

Developing a new and innovative coating for corrosion protection, respecting general technical specifications, is often tricky due to the numerous possible pathways and very high interest of many industries. Continuous progress and research for efficient and cost-effective solutions to a world affecting problem make the field of smart coatings both incredibly exciting and competitive. Since corrosion of metals will lead to their progressive dissolution and important losses of their physical properties, numerous applications are threatened by its development. Encapsulation is widely studied and has applications in many fields such as the food industry, cosmetics, pharmaceutics and materials science. Due to the different requirements in terms of size, function, compatibility etc. a staggering number of architectures exists and providing an exhaustive list is not useful and almost impossible. Therefore, we here deal with particles formed using colloids for two main reasons: it is a quite simple process that does not require an heavy equipment, and this kind of syntheses can be carried out at lab scale and transferred to industrial scale. Although they are sometimes considered as encapsulation techniques and reported in the literature for similar applications, hollow fibers209,210 and Layered Double Hydroxides149,211 (LDH) are beyond the scope of this literature review. In order to be as clear as possible, the terms we use hereafter are based on a IUPAC recommendation from 2012212. This means that are called nanoparticles and microparticles particles whose size ranges from 1 to 100 nm and 0.1 to 100 µm respectively. When speaking about spherical particles, “capsules” designs hollow particles with a solid shell and an inner space whereas “spheres” mean there is no distinction between the inner and outer parts of the particle. The terms particles and containers are used without distinction. Nature of the containers is naturally linked to their reactivity, release and applications, hence dissociating each parameter can be meaningless. In order to structure this part, we will first deal with the containers’ formations, i.e., the formation technique, how to achieve loading and the nature of the particle or shell, before looking at the release mechanisms that can be used. Since we want to use containers as reservoirs in a host matrix, we will then identify the similar coatings that exist in order to see how capsules or spheres are incorporated in a polymeric matrix and the consequences of this addition.

CN1297613C (2007-01-31) Surface modified nano calcium carbonate for corrosion resistance paint, CNOOC Changzhou Paint & Coatings Industry Research Institute
The present invention relates to surface modified nano calcium carbonate for corrosion resistance paint. A used modifying agent is titanate containing pyrophosphate groups and hydroxyacetate groups and has a structural formula as (I), wherein R1 and R2 are paraffin hydrocarbon groups from C5 to C10. The dosage of the modifying agent is 0.5 to 3.0% of the weight of untreated nano calcium carbonate solid. The nano calcium carbonate can be used for enhancing the corrosion prevention performance of the corrosion resistance paint. The object of the present invention is to provide a kind of surface modified nano calcium carbonate that improves anticorrosion with coat erosion sexual function that has, be used to improve the Corrosion Protection of coating.

US-9879349-B2 2018/01/30: Method for coating metallic surfaces with an aqueous composition, Kolberg Thomas, Walter Manfred, Schubach Peter

The invention relates to a process for coating metallic surfaces with a composition containing at least one of a silane, silanol, siloxane or polysiloxane that is capable of condensation, water and optionally an organic solvent. The composition also contains compound containing Ti, Hf, Zr, Al or B; and at least one type of cation or an organic compound d) selected from monomers, oligomers, polymers, copolymers and block copolymers. The coating freshly applied with this composition is rinsed with a fluid and is not dried thoroughly before this rinsing step so that the compound capable of condensation does not condense substantially before the rinsing step. The invention relates to a process for coating metallic surfaces with an aqueous composition containing at least one silane and/or related silicon-containing compound and optionally other components, which is treated further, e.g., at temperatures above 70° C., without drying the coating. The processes most commonly employed hitherto for the treatment of metallic surfaces, especially parts, coil or coil, portions made of at least one metallic material, or for the pre-treatment of metallic surfaces prior to lacquering are frequently based on the one hand on the use of chromium (VI) compounds, optionally together with diverse additives, or on the other hand on phosphates, e.g., zinc/manganese/nickel phosphates, optionally together with diverse additives.
Because of the toxicological and ecological risks associated especially with processes using chromate or nickel, alternatives to these processes in all the areas of surface technology for metallic substrates have been sought for many years, but it has repeatedly been found that, in many applications, completely chromate-free or nickel-free processes do not satisfy 100% of the performance spectrum or do not offer the desired safety.
EP2632855A1 - Production of high purity precipitated calcium carbonate, Inventor - Bahman Tavakkoli, Jörg Sötemann, Michael Pohl, Thomas Schmölzer; Current Assignee Omya International AG

The present invention relates to a process for the preparation of precipitated calcium carbonate comprising the steps of a) providing and calcining calcium carbonate comprising material; b) slaking the reaction product obtained from step a) with an aqueous ammonium chloride solution; c) separating insoluble components from the calcium chloride solution obtained from step b); d) carbonating the calcium chloride solution obtained from step c); e) separating the precipitated calcium carbonate obtained from step d); the precipitated calcium carbonate obtained by this process, as well as uses thereof.

Electrically Conductive polymers for the use as novel pigments in Advanced Coatings - Joseph Byrom (April 2017) - A Dissertation Submitted to the Graduate Faculty of the North Dakota State University of Agriculture and Applied Science
With the push to more environmentally friendly materials to solve some of the biggest challenges in the coatings industry, electrically conductive polymers (ECPs) are seen as a flexible solution due to their unique properties. ECPs are seen as an attractive substitute to the current metallic materials used in applications such as printable electronics, anti-static protection, and corrosion mitigation. Polypyrrole (PPy) is seen as a popular class of ECPs due to its inherent high electrical conductivity, resistance to environmental degradation, and ease of synthesis. The first part of this work was to study the ability of polypyrrole to be synthesized through a novel photochemical process. This method eliminated the need to stabilize particles in a suspension and deposit an electrically conductive film onto a variety of substrates. The second part of this work was to synthesize functional versions of PPy that could further be crosslinked into the coating matrix to improve bulk physical properties through better interaction between the functional filler and the organic coating matrix. The last part of this work is based off prior work at NDSU on AL-flake/PPy composites. This study took the development of these pigments further by incorporating organic anions known to inhibit corrosion and study their efficacy. Advanced analytical methods such as Conductive Atomic Force Microscopy was used to study the electrical properties of PPy. In addition, advanced electrochemical tests such as Electrical Impedance Spectroscopy (EIS), Scanning Vibrating Electrode Technique (SVET), Linear Polarization (LP), and Galvanic Coupling (GP) were conducted alongside traditional accelerated weathering techniques such as ASTM B117 and GM 9540 to determine the corrosion resistance of the synthesized coatings.

US Patent US8987352B1 (24.03.2015) – Phase separated self-healing polymer coatings;
Inventor: Runqing Ou, Kenneth Eberts, Ganesh Skandan; Assignee NEI Corp

Phase separated self-healing polymer coatings having a “biphasic” thermoset/thermoplastic morphology to achieve self-healing. The biphasic structure has: (i) a major “load-bearing” thermoset phase that has superior strength and performs major mechanical and structural functions, and (ii) a “self-healing” phase of a thermoplastic healing agent to repair the material and restore its mechanical and structural integrity after being damaged. The phase-separated morphology is achieved through phase separation via a reaction process. A self-healing polymer coating comprising: a) polyurethane thermoset resin; b) polycaprolactone (PCL) thermoplastic present as sub-micron generally spherical particles formed in situ by phase separation via reaction and dispersed in a matrix of the thermoset resin; and c) the thermoplastic and thermoset forming a transparent structure wherein the thermoset is a load-bearing phase performing major mechanical and structural functions and wherein the thermoplastic serves as a self-healing phase to repair cracks and other damages in the material to restore its mechanical and structural integrity after damage, wherein the polyurethane comprises 80-90 wt. % and the PCL is 10 to 20 wt. %.

US Patent 8664298B1(04.03.2014) - Self-healing polymer nanocomposite coatings for use on surfaces made of wood; Inventor - Runqing Ou, Kenneth Eberts, Ganesh Skandan, Sau Pei Lee, Robert Iezzi, Daniel E. Eberly, Assignee: NEI Corp

Phase separated self-healing polymeric wood coatings having a “biphasic” thermoset/thermoplastic morphology to achieve self-healing. The biphasic structure has: (i) a major “load-bearing” thermoset phase that has superior strength and performs major mechanical and structural functions, and (ii) a “self-healing” phase of a thermoplastic healing agent to repair the material and restore its mechanical and structural integrity after being damaged. The phase-separated morphology is achieved through phase separation via a reaction process. Methodologies for achieving the above mentioned “biphasic” structure in solvent borne thermally cured resin, waterborne resin, and solvent borne UV-curable resin are described. A method for providing a self-healing polymeric water borne wood coating comprising the steps of: a) mixing a water incompatible polycaprolactone (PCL) thermoplastic with at least one polyol monomer of a thermoset; b) adding a dihydroxyl carboxylic acid and a crosslinker to the mixture; c) adding an isocyanate monomer to the mixture; d) forming a thermoset prepolymer with terminating isocyanate groups by heating the mixture; e) adding a tertiary amine to the mixture to neutralize the acid groups from the dihydroxyl carboxylic acid; f) pouring the neutralized hot prepolymer/PCL thermoplastic mixture into water with agitation to form an emulsion; g) adding a chain extending amine to the emulsion: h) coating the emulsion unto a wood surface; and i) curing the coated emulsion so as to form a transparent coating on the wood surface having a unique thermoset and thermoplastic phase separated structure formed by phase separation during the curing reaction with the phase separated features being under 1 micron in size, wherein the thermoset forms a load-bearing phase performing major mechanical and structural functions and wherein the PCL thermoplastic forms a self-healing phase to repair cracks and other damages in the material to restore its mechanical and structural integrity after damage.

4. Objective of the Invention:
The objective of this innovation is to develop a high-performance intelligent coating technology for effective corrosion protection of mild steel in corrosive environment. The aim was to design multi-layered conjugated polymer, nano calcium carbonate composites and investigated their compatibility with an epoxy coating to check their performance as corrosion preventive system for mild steel and to determine the appropriate mechanism to trigger self-releasing of the inhibitors from the nanoparticles. The purpose was to develop an intelligent coating by doping conjugated polymer with specific dopant encapsulated with nanoparticles in an epoxy coating, and to characterize the corrosion protection of the mild steel in corrosive environments.

5. Summary of the invention:

The present invention describes a process of synthesizing conducting polymers encapsulated with nano calcium carbonate in a specific doping medium. The method comprising:
• Preparation of nano calcium carbonate and encapsulation of these nano particles on conjugated polymer matrix like PEDOT, polyaniline, poly (o-methyl aniline), poly (o-ethoxy aniline), poly phenoxy aniline and copolymers of ethylene dioxythiophene with aniline and its analogues.
• Coating of these blends along with specific epoxy and paint formulations and testing and evaluation the panels under saline environment as per ASTM B117, ASTM D3359-09 & ASTM D522M/D522-93a.
6. Detailed Description of the invention:
Majority of industries are intrinsically faced with the problem of corrosion and steps for protection of materials from corrosion has been of great attention to them. Although many corrosion prevention techniques are in process, it is required to increase the life of the components further. Use of protective coating has been one of the most efficient methods for protection of metals from corrosion. Chromates based coating are considered to be highly most adorable technology for the protection of iron, but these coating are found to be very hazardous as Cr (VI) is very toxic and is considered dangerous due to its carcinogenic nature. Moreover, other metal rich primers such as lead or zinc require high pigment volume concentration and have adverse effect on environmental. Taking into consideration, the limitations of existing coating system along with speedily growing industrializations and increasing pollutants, there is an urgent need to discover environmentally intelligent coatings to protect the metals from corrosion having excellent corrosion inhibitive property.
Conjugated 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.
The present innovation describes a process of designing Intelligent coatings by encapsulating nano calcium carbonate in conjugated polymer matrix in the presence of specific doping medium and these nano composite blends can be used in epoxy and paint formulation for the protection of mild steel surface from corrosion. For evaluating the performance of the blended composition, various electrochemical and salt spray tests were carried out to examine the performance of the designed conjugated polymer nano calcium carbonate blend encapsulated in epoxy and powder coated on mild steel surface.

7. Brief Description of the Drawings:
In the drawings accompanying the specification, Fig 1 is flow chart of the of encapsulation of nano particles of calcium carbonate embedded in copolymer matrix of EDOT & AN matrix giving different steps for evaluation & characterization

In the drawings accompanying the specification, Fig 2 is a schematic representation of copolymer synthesis encapsulated with nano particles in the presence of doping medium

In the drawings accompanying the specification, Fig 3 are the images of (A) cross cut adhesion test (B) Mandrel Bend test and (c) Taber Abrasion Test of (a) Epoxy coating (b) epoxy with Poly (EDOTAN) and (C) epoxy with Poly (EDOTAN)/CaCO3 blend coating

In the drawing accompanying the specification, Fig 4 the XRD of (a) nano calcium carbonate obtained using ball milling and (b) nanocomposite of Poly (EDOTAN) blended with nano calcium carbonate.

8. The following examples are given to illustrate the process of the present invention and should not be construed to limit the scope of the present invention:

Example 1: Synthesis of nano calcium carbonate

50 gms of conventional calcium carbonate are ball milled in a Retsch ball mill PM 400/2 where tungsten carbide balls are taken in a jar containing isopropanol and ball milled for a period of 8 hours so that nanoparticles of calcium carbonate are formed. The powder is then taken for XRD and crystallite size was found to be 50 nm. In a second approach, 13.125 gms of sodium bicarbonate and 10.33 gms of calcium chloride are taken in 1.0 litre of distilled water and mixed with thorough stirring in a temperature of 120-160oC; precipitate is filtered and dried and kept in isopropanol solvent so that no agglomeration of nano calcium carbonate nano particles takes place. These nanoparticles are then used for blended with conjugated polymers.

Example 2: Synthesis of Co-polymer of EDOT and Aniline

0.1 M of ethylene dioxythiophene (EDOT) was mixed with 0.1 M of aniline are taken in 1.0 lt. of distilled water containing 0.2 M of lauryl sulphonic acid and 0.2 M of phosphoric acid in a double walled reactor which has been kept at 2-5oC and stirred continuously. To this mixture, 0.2 M of ammonium persulphate is added dropwise in a period 0f 2 hours so that the copolymerization starts initially with the formation of cation radicals leading to the formation of di-cations and finally formation of the copolymer. The stirring was continued for 4-6 hours. After polymerization was complete, the precipitate of copolymer was filtered and washed thoroughly with distilled water and finally the copolymer was dried at 50-60oC in an oven.

Example 3: Synthesis of Co-polymer of EDOT and Aniline on nano calcium carbonate
0.1 M of ethylene dioxythiophene (EDOT) was mixed with 0.1 M of aniline are taken on 2 % of nano calcium carbonate and mixed thoroughly so that EDOT and aniline are completely absorbed on nano calcium carbonate. This mixture is then taken in 1.0 lt. of distilled water containing 0.2 M of lauryl sulphonic acid and 0.2 M of phosphoric acid in a double walled reactor which has been kept at 2-5oC and stirred continuously. To this mixture, 0.2 M of ammonium persulphate is added dropwise in a period of 2 hours so that the copolymerization starts initially with the formation of cation radicals leading to the formation of di-cations and finally formation of the copolymer. The stirring was continued for 4-6 hours. After polymerization was complete, the precipitate of copolymer was filtered and washed thoroughly with distilled water and finally the copolymer containing nano calcium carbonate was dried at 50-60oC in an oven.

Example 4: Synthesis of Co-polymer of EDOT and Aniline on nano calcium carbonate
0.0.05 M of ethylene dioxythiophene (EDOT) was mixed with 0.05 M of aniline are taken on 2 % of nano calcium carbonate and mixed thoroughly so that EDOT and aniline are completely absorbed on nano calcium carbonate. This mixture is then taken in 1.0 lt. of distilled water containing 0.2 M of lauryl sulphonic acid and 0.2 M of phosphoric acid in a double walled reactor which has been kept at 2-5oC and stirred continuously. To this mixture, 0.1 M of ammonium persulphate is added dropwise in a period of 2 hours so that the copolymerization starts initially with the formation of cation radicals leading to the formation of di-cations and finally formation of the copolymer. The stirring was continued for 4-6 hours. After polymerization was complete, the precipitate of copolymer was filtered and washed thoroughly with distilled water and finally the copolymer containing nano calcium carbonate was dried at 50-60oC in an oven.

Example 5: Salt spray, Adhesion tests and bend test coatings of the nanocomposite
Mild steel specimens were polished metallographically by grinding with emery papers of 120, 600 and 800 grit size to attain a smooth finish, prior to the coating treatment. The powder coating formulations were blended with epoxy resin. A homogenous mixture of well dispersed nanocomposites in epoxy was obtained after ball milling. The coatings were applied on mild steel specimens using an electrostatic spray gun held at 67.4 KV potential with respect to the substrate (grounded). The powder coated mild steel specimens were cured at 150?C for 30 minutes. The adhesion of the coating was tested by cross cut adhesion test and bend test as per ASTM standards. The steel specimens coated with epoxy coating were designated as EC, epoxy with 1.0, 2.0 and 3.0 wt. % loading of nanocomposite obtained by copolymerizing EDOT with aniline which are encapsulated on nano particles of calcium carbonate. Salt spray, adhesion test and bend test of the nanocomposites blended with epoxy on mild steel surface was tested as per ASTM B117, ASTM D3359-09 & ASTM D522M/D522-93a. Mild steel specimens coated with epoxy and epoxy with nanocomposites were found to pass the cross-cut adhesion test as no detachment of the coating was observed during the test. Figure 3 illustrate the photographs of the coatings subjected to deformation by bending to 175?. The surface of the epoxy coating exhibited severe cracking that propagate from the edges to the center of the coating. However, a qualitative good adhesion was observed for epoxy coatings with 2.0wt.% (PEDOTAN) and 3.0wt.% (PEDOTAN) loading nano particles of calcium carbonate. Further, the coating produced with 3.0 wt. % loading of nano particles of calcium carbonate encapsulated in P(EDOTAN) conjugated polymer nanocomposite showed appearance of few cracks at the edges of the coating. This could be due to the higher loading of composite; that had detrimental effect on the adhesion of the coating to its substrate.

9. Advantages:
The present invention elaborates a novel method to encapsulate nano particles of calcium carbonate in conjugated polymer matrix in the presence of specific doping medium so that the designed nanocomposites when blended with bisphenol polyester epoxy in a specific ration gives excellent corrosion inhibition response. Nanocomposite coatings formulations have advantages over conventional paint formulations or coatings that these contain conjugated matrix which takes up electrons when corrosion initiates and the presence of oxygen in air coverts the reduced form again to oxidized form resulting in coating intact on the surface. Moreover, no volatile organic compounds (VOCs) are released when these nanocomposites are used.

We Claim:
1. Intelligent Smart Coating of Conjugated polymer blended with nano calcium carbonate and doped in a specific doping medium leading to the formation of nano composite which when blended with (bisphenol A) + polyester epoxy is used for the prevention of corrosion having (a) conjugated polymer made up from ethylene dioxy thiophene and aniline co-monomer leading to the formation of Poly co (EDOT-AN) copolymer encapsulated with (b)1 to 5 wt. % of nano calcium carbonate (c) the doping medium selected from lauryl sulphonic acid, phosphoric acid, dodecyl benzene sulphonic acid and combination of phosphoric acid with LSA and DBSA (d) blended composite mixed with selective epoxy in the ration of 1 to 5% and testing of the epoxy blended conjugated polymer matrix as per ASTM standards and electrochemical evaluation using Tafel plot measurements
2. A process for the preparation of Smart Intelligent Coatings as claimed in claim 1, wherein the conjugated polymer is designed using specific combinations of EDOT and Aniline monomers and copolymers were used for the designing of specific nano composites
3. A process for the preparation of Smart Intelligent Coatings as claimed in claim 1, wherein nano calcium carbonate was prepared by ball milling calcium carbonate in Retsch ball mill PM 400 for 8 hours at rpm of 400
4. A process for the preparation of Smart Intelligent Coatings as claimed in claim 1, wherein doping medium for the synthesis of copolymer of EDOT & An was selected from lauryl sulphonic acid, phosphoric acid and dodecyl benzene sulphonic acid and combination of different proportions of phosphoric acid with LSA & DBSA
5. A process for the preparation of Smart Intelligent Coatings as claimed in claim 1, wherein epoxy resin used for nanocomposite coating has the following composition: resin {epoxy (bisphenol A) + polyester} (70%), Flow agent (D-88) (2.3%), degassing agent (benzoin) (0.7%), fillers (TiO2 and BaSO4) (27%) which was used for powder coating on mild steel surface
6. A process for the preparation of Smart Intelligent Coatings as claimed in claim 1 wherein nano composite blended with epoxy was tested in saline water corrosive conditions as per ASTM B117 standard