Formulation for the production of Anti-corrosive ternary nanocomposite coating and bulk material with high performance properties

Abstract

The present invention relates to a ternary nanocomposite coating having high- performance anti-corrosive properties when applied to metal surfaces. In particular, the invention relates to an anti-corrosive coating for metals which, due to its composition, is applied in a fast, efficient, highly safe and environmentally friendly manner. The invention also relates to a bulk material for the production of elements and objects with anti-corrosive properties.

Description

“FORMULATION FOR THE PRODUCTION OF ANTI-CORROSIVE TERNARY NANOCOMPOSITE COATING AND BULK MATERIAL WITH HIGH PERFORMANCE PROPERTIES”DESCRIPTIONTECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a formulation for the production of a ternary nanocomposite coating having high-performance anti-corrosive properties, when applied to metal surface. In particular, the invention relates to an anti-corrosive coating for metals which, due to its composition, is applied in a fast, efficient, highly safe and environmentally friendly manner. Furthermore, the invention relates to a bulk material with mechanical, thermal, water-repellent and surface scratch-resistant properties.STATE OF THE PRIOR ART

[0002] In order to protect metals from corrosion, there are currently used various technologies, the most common of which are galvanic treatments and polymer resinbased coatings.

[0003] Galvanic treatments in general, such as zinc plating, chromium plating, nickel plating and others, consist of coating a metal with a thin layer which ranges from 1 to 10 pm by means of electrolytic deposition. This technology, which has been widely used and known for a long time, offers a fairly effective solution against corrosion. However, it has a number of application limitations, such as the treatment of rather small workpieces, the inability to process the joints between different workpieces, a rather short durability unless complemented by a surface passivation based on chromium VI which improves its resistance to atmospheric agents. In general, galvanic treatments pose safety and environmental problems because they involve the use of toxic and hazardous metals such as cadmium, chromium (VI), lead, mercury in the various process steps. The disposal of carcinogenic reaction products such as chromic acid (approx. 80-90 % in the treatment which uses electrolyte based on chromic acid CR6+and sulfuric acid) has led to the development of alternative techniques, such as electrodeposition of chromium from trivalent chromium-based solutions. These alternatives solve environmental problems, but they are still reserved for a niche market because they require skilled labour and sophisticated deposition processing equipment. However, the replacement of chromium is a critical point for the metallurgical industry in accordance with the current restriction irule for hazardous substances such as hexavalent chromium (Directive 2002 / 95 / EC). As a matter of fact, marketing electrical and electronic equipment that does not comply with the European Directive on eco-compatibility (RoHS) (2002 / 95 / EC) has been prohibited since first July 20026. Subsequent amendments / repeals, such as the most recent D.L.27 / 2014 (RoHS III), have increased the list of substances to be banned. Currently, the directive does not specify a deadline for compliance for companies. However, this deadline must be adopted in the legislation of the Member States of the European Union and applied to products sold in Europe, irrespective of their place of manufacture.

[0004] As regards polymer resin coatings, various organic systems, such as epoxy resin, acrylic, polyaniline, polyurethane, alkyd, polymethyl methacrylate, polystyrene, polyamide, polypropylene, polydopamine, silane and polydimethylsiloxane, are widely used in the anti-corrosion of metals due to their exceptional properties to act as a physical barrier. However, during application, micro-cracks and holes are generated due to the high cross-linking density of organic coatings, which lead to a certain permeability to H2O, O2 and Cl’ in corrosive media. The invasion of these substances obviously affects the anti-corrosive performance of the coating and accelerates the corrosion of metals.

[0005] Therefore, conventional coatings cannot provide long-term protection.

[0006] Furthermore, polymer coatings currently used as anti-corrosive in several areas are usually multi-layer systems that require an adhesion primer (generally organic silane / epoxy primers, inorganic primers with Zn / silica phosphates combined with epoxy and / or polyethylene and / or polyurethane and / or polypropylene and / or polyvinyl substances). Zinc plating treatments are sometimes also combined with a polymer coating to replace the chemical passivation treatment with chromium. Therefore, these systems require the application of two or more layers of different products to achieve effective anti-corrosive properties, resulting in a low yield in terms of time and therefore high costs, as well as expensive production processes which require toxic reagents and resulting in inhomogeneous dispersions at microscopic level at most.

[0007] For example, document US2020 / 0121562 describes a resinous composition and biomedical restoration including glass fibre fillers on whose surface bioactive hydroxyapatite particles are deposited. The filler is used in a resinous system, which is only of organic nature and hardens so as to restore damaged bone or dental tissue. Therefore, the filler is functionalised with ceramic particles before being embedded into the resinous matrix for a specific biomedical purpose. In these materials, there is a clearmacroscopic separation between the organic phase (resin) and the inorganic phase (ceramic-filler).

[0008] Document US2005 / 0191480 describes a method for applying support catalyst coatings on ceramic supports, in particular a method for coating ceramic substrates with coating catalysts. The purpose of this method is to produce ceramic filters for the abatement of harmful emissions of exhaust gases from diesel engines.

[0009] Document W024002950 describes a method for preparing a composite material specifically based on graphene nanotubes. The proposed preparation method lies in the mechanical grinding (by means of a ball mill) without or with optional use of solvents. The nature of the preparation process is such to allow to obtain composite materials can be obtained in a single step which is based on grinding, but not on specific chemical reactions. Furthermore, thermoplastic polymers with highly toxic reagents are used and which must be removed under vacuum and at high temperatures.

[0010] Document US2019 / 0338146 describes a functionalised graphene-based coating composition for the anti-corrosive treatment of metal materials. In particular, the composition is a suspension comprising multiple sheets of graphene, particles of an anticorrosive pigment or sacrificial metal, in which sheet graphene has a single layer or has a few layers selected from of a graphene material as is (pristine graphene), or a functionalised graphene. Furthermore, the coating composition does not contain any siliceous binder or microbeads dispersed therein.

[0011] Document WO2019217514 describes a graphene-based coating suspension such as an anti-corrosive, comprising multiple sheets of graphene each with two parallel opposite surfaces, a thin layer coated with an anti-corrosive pigment or sacrificial metal covering at least part of said surfaces, and a bonding resin dissolved or dispersed in a liquid medium, wherein graphene is selected graphene as is (pristine graphene) or functionalised graphene or combination thereof. The suspension does not contain any glass, ceramic or polymer microbeads.SUMMARY OF THE INVENTION

[0012] Therefore, the technical problem underlying the present invention lies in overcoming the drawbacks of the prior art.

[0013] Such problem is overcome by a formulation for the production of a dispersion for the coating for metal surfaces that are highly performing as anti-corrosive, safe and recyclable, or for a bulk material with high mechanical properties.

[0014] Therefore, a first object of the present invention is a formulation for the production of a ternary nanocomposite dispersion for coating metal surfaces with increased anticorrosive capabilities.

[0015] A second object is a formulation for the production of a ternary nanocomposite dispersion comprising substances that bind together in a synergistic and highly effective manner.

[0016] A third object is a ternary nanocomposite coating obtained by applying a dispersion comprising environmentally friendly and recycled substances.

[0017] A further object is a method for the treatment of metal surfaces including the use of the anti-corrosive coating of the invention.BRIEF DESCRIPTION OF THE FIGURES

[0018] Further characteristics and advantages of the ternary nanocomposite formulation and the method for producing a high-performance dispersion of the invention will be more apparent from the following description provided purely by way of non-limiting example, with reference to the attached figures, wherein:- figure 1 shows a chart relating to a potentiostatic test on metal substrates: untreated metal, galvanized metal and coated metal according to the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0019] The idea underlying the present invention is to try to formulate a composition that can take the advantages of each of the aforementioned prior art techniques while avoiding the negative aspects. As a matter of fact, the anti-corrosive coating has been developed by synergistically combining the advantages of organic polymers with the advantages of inorganic substances. In particular, epoxy resins have important properties of adhesion to different types of substrates and ease of application; by contrast, as explained, crosslinking the resins can easily form micro-cracks and need to be applied in multiple layers. Inorganic materials, on the other hand, have good coating properties, but involve methods processed using substances that are very harmful for the environment and highly toxic for humans.

[0020] In order to combine the advantages while avoiding the problems of each of the aforementioned components, it has been thought to formulate a hybrid composition with organic and inorganic components in a ternary system in which the organic component is closely interconnected in nanometric, and not microscopic, scale to the inorganic component. The ternary system basically consists of a natural or recyclable or syntheticderived polymeric organic component for the adhesion of the system to the substrate to be coated, an inorganic component forms a sol-gel with an organic component and an additional inorganic component which imparts specific chemical / physical properties to the coating.

[0021] It has been observed that through the sol-gel method there may be developed coatings that can change the properties of the surfaces. The invention is based on this type of method and it was modified so to lead to the formation of hybrid organic-inorganic coatings with a nanocomposite structure capable of overcoming the aforementioned drawbacks. In particular, the sol-gel technology relies on liquid phase precursors typically comprising alkoxides, metal chlorides or metalloids that take part in the hydrolysis and condensation reactions to form a colloidal solution of solid particles with dimensions comprised between 1 nm and 1000 nm in a liquid phase, that is a sol. The sol is then thermally treated to remove the liquid phase trapped in its reticulum in order to stabilize the structure and obtain the desired properties.

[0022] Therefore, the organic component of the formulation is represented by an epoxy resin preferably of natural origin with a cross-linking agent, while the inorganic component is given by a metal alkoxide precursor which reacts by hydrolysis and condensation to form the colloidal solution of solid particles, an organic silane precursor and a filler. In addition, the formulation also comprises an aqueous component and an alcohol such as solvents and a pH regulator to promote reaction conditions between the above components.

[0023] The formulation of the invention, called COATING WM-A, therefore, comprises the following substances present as percentages of the total liquid phase weight of the formulation:- 15-85% of epoxy monomers or oligomers of natural and / or recyclable origin;- 5-20% of inorganic silane precursor;- 1 -10% of an organic silane precursor;- 1 -6% of an alcohol;- 0.5-8% of water;- 3-40 % of a cross-linking agent for epoxy monomers or oligomers;- 0.1 -1 % of a pH regulator;- 0.01 -6% of a filler.

[0024] The combination of an organic silane with an inorganic silane has proved particularly important given that in obtaining a sol-gel, resulting from reacting the twosilanes, the organic silane acts as a coupling agent facilitating the interaction with the organic monomers which will be added subsequently and that will then undergo a cross- linking / cure process. Inorganic silane, on the other hand, confers to the nanometric silicious component that remains dispersed in the liquid solution and does not compact into a solid, like it instead happens in the compositions of the prior art described above containing ceramic components.

[0025] In general, epoxy resins are a family of thermosetting polymeric materials, which when hardened do not give rise to reaction by-products and achieve their final performance characteristics. The resin hardening process is carried out by hardening agents. Epoxy resins are also a class of materials that are very important and are exploited due to their good mechanical, thermal and chemical properties. These properties can be summarised in: high rigidity and strength, low hardening shrinkage, excellent chemical resistance, outstanding processability, good electrical insulation properties, strong adhesion / affinity to heterogeneous materials, barrier effect.

[0026] Commercial epoxy resins are mainly based on diglycidyl bisphenol A ether (DGEBA) consisting of bisphenol A (BPA) and epichlorohydrin. In particular, the epoxy resin according to the present invention is the organic component of the above-mentioned ternary system, whose molecules or precursors of natural and / or synthetic origin but with recyclable capacities. Therefore, these molecules preferably derive from non-petroleum or fossil sources.

[0027] The natural resin according to the present invention originates from vegetable oils or carbohydrates, preferably selected from those obtained from epoxy processes of simple carbohydrates, fatty acids or their esters, or saccharides, or phenols and polyphenols, or natural resins produced by trihydroxybenzoic acid, vegetable resins produced from glycerine-based ligneous extracts, from plant bark, flowers o buds, and by lignin and derivatives, that is the vegetable resins produced by resin acids such abietic acid or dihydroabietic acid or dehydroabietic acid, isosorbide-based natural resins or the vegetable resins produced by itaconic acid, vegetable resins produced by furfural.

[0028] Among the carbohydrates used, the most common are monosaccharides and disaccharides, as limonene derivatives, maltitol, sorbitol and sucrose, which through etherification and subsequent epoxidation processes for example, originate epoxy allyl sucrose (EAS) resin, epoxy crotyl sucrose (ECS) resin and epoxy methallyl sucrose (EMS) resin, as well as analogues of sorbitol and maltitol.

[0029] Among the natural fatty acids, the most studied are derived from soybean oil, coconut oil, sunflower oil, rapeseed oil, palm oil, olive oil, cashew nut shell extract, cardanol, linseed oil. These oils are known to have a variable content of fatty acids, the most common of which include stearic, palmitic, oleic, linoleic and linolenic acid. Basically, the fatty acids which can be epoxidized for use in the present invention are preferably those with hydrocarbon chain with length comprised between C12-C24.

[0030] Other resins can be obtained starting from tannic acid.

[0031] Another widely available, environmentally friendly and economical material is cellulose, which thanks to its fibrous polysaccharide nature is a biomaterial with high strength and other superior mechanical properties, which make it suitable also in the field of nanotechnologies.

[0032] Synthetic epoxy resins suitable for the invention are in particular aromatic epoxy resins, preferably glycidylation products of: bisphenol A, bisphenol F or bisphenol A / F, where A is acetone and F is formaldehyde, which served as starting materials for the preparation of these bisphenols. In the case of bisphenol F, there may also be present position isomers, in particular derived from 2,4'- or 2,2'-hydroxyphenyl methane. Other derivatives are those of dihydroxybenzene such as resorcinol, hydroquinone or pyrocatechin; further bisphenols or polyphenols such as bis (4-hydroxy-3-methylphenyl) methane, 2,2-bis (4-hydroxy-3-methylphenil) propane (bisphenol-C), bis (3,5-dimethyl-4- hydroxyphenil) methane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, 2,2-bis (3,5- dibromo-4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3 ter-butylphenyl) propane, 2,2- bis (4-hydroxyphenyl) butane (bisphenol B), 3,3-bis (4-hydroxyphenyl) pentane, 3,4-bis (4-hydroxyphenyl) hexane, 4,4- bis (4-hydroxyphenyl) heptane, 2,4-bis (4-hydroxyphenyl) -2-methyl butane, 2,4-bis (3,5-dimethyl-4-hydroxyphenyl) -2-methyl butane, 1 ,1 -bis ( 4- hydroxyphenyl) cyclohexane (bisphenol-Z), 1 ,1 -bis (4-hydroxyphenyl) -3,3,5-trimethyl cyclohexane (bisphenol TMC), 1 ,1 -bis (4-hydroxyphenyl) -1 -phenyl ethane, 1 ,4-bis [2- (4-hydroxyphenyl) -2-propyl] benzene (bisphenol-P), 1 ,3-bis [2- (4-hydroxyphenyl) -2- propyl] benzene (bisphenol-M), 4 ,4'-dihydroxy diphenyl (DOD), 4,4'-dihydroxy benzophenone, bis (2 -hydroxynapht-1 -yl) methane, bis (4-hydroxynapht-1 -yl) methane, 1 ,5-dihydroxynaphthalene, tris (4- hydroxyphenyl) methane, 1 ,1 ,2,2-tetrakis (4- hydroxyphenyl) ethane, bis (4-hydroxyphenyl) ether or bis (4-hydroxyphenyl) sulphone. Further substances are the condensation products of phenols with formaldehyde obtained under acidic conditions, such as phenol novolacs or cresol novolacs, also called bisphenol novolacs F; aromatic amines such as aniline, toluidine, 4,4'-methylene diphenyldiamine, 4,4'-methylene diphenyl-di (N-methyl) amine, 4,4'- [1 ,4-phenylene-bis (1 - methyl ethylidene )] bisaniline (bisaniline-P) or 4,4'- [1 ,3-phenylene-bis (1 -methyl ethylidene)] bisaniline (bisaniline-M). Further suitable epoxy resins are in particular aliphatic or cycloaliphatic polyepoxide glycidyl ethers of alcohols C2 -C30 that are saturated or unsaturated, branched of unbranched, cyclic or with open chain, di-, tri- or tetra-functional C2 -C30, in particular ethylene glycol or, propylene glycol, butylene glycol, hexanediol, octanediol, polypropylene glycols, dimethylcyclohexane, neopentyl glycol, dibromo neopentyl glycol, castor oil, trimethylolpropane, trimethyl ethane, pentaerythrol, sorbitol or glycerol, or glycerol alkoxylate or trimethylolpropane alkoxylate; a bisphenol liquid resin A, F or hydrogenated A / F, or glycidylation products of bisphenol A, F or -hydrogenated A / F; an N-glycidyl derivative of amides or heterocyclic nitrogenous bases, such as triglycidyl cyanurate or triglycidyl isocyanurate, or reaction products of epichlorohydrin with idantoine. There may also be used epoxy resins obtained from the oxidation of olefins, in particular vinylcyclohexene, dicyclopentadiene, cyclohexadiene, cyclododecadiene, cyclododecatriene, isoprene, 1 ,5-hexadiene, butadiene, polybutadiene or divinylbenzene. A bisphenol-based liquid resin, particularly a diglycidyl bisphenol A ether-A, bisphenol-F or bisphenol-A / F, is preferred as synthetic epoxy resin.

[0033] Further materials which can also be used combined with the epoxy resins are acrylic resins, such as for example 1 ,4-bis(ethenyl)benzene, 2-(phenyl methoxy methyl)oxirane, styrene poly hydroxyethyl methacrylate (pHEMA) 2-hydroxyethyl acrylate(2-HEA) and 2-hydroxypropyl acrylate (2-HPA) methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, butyl methacrylate, n-propyl, isopropyl ester of acrylic acid, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n- pentyl ester of acrylic acid, 1 ,4-butanediol dimethacrylate, 1 ,3-butanediol dimethacrylate, 1 ,6-hexanediol dimethacrylate, 1 ,9-nonanediol dimethacrylate, 1 ,10-decanediol diacrylate, pentaerythritol tetraacrylate, urethane acrylate resin, urethane acrylate methacrylate resine, isobornyl acrylate, acrylic acid-2-ethyl butyl ether, acrylic acid-2- ethyl caproite, acrylic methyl cyclohexyl, pentyl ester, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, n propyl methacrylate, n- BMA, isopropyl propionate, isobutyl methacrylate, n-amyl methacrylate, isopentyl methacrylate, secondary butyl ester of methacrylic acid, tert-butyl methacrylate, methacrylic acid -2- ethyl butyl ester, methyl methacrylate cyclohexyl base, cinnamic ester of methacrylic acid, cyclohexyl methacrylate, methacrylic acid pentylester ring, isobornyl methacrylate and combinations thereof.

[0034] Preferably, the epoxy resin is present in the formulation in amounts comprised between 35-65%, more preferably between 40-60%.

[0035] The inorganic silane precursor is preferably an alkoxysilane selected from molecules that can give a sol-gel reaction with organic silane to provide a support crosslink. This precursor may for example be: tetraethoxysilane (TEOS); tetramethoxysilane (TMOS), methyltrimethoxysilane. Furthermore, preferably it is present in the formulation in an amount comprised between 7-15%, more preferably between 10-13%.

[0036] The organic silane precursor reacting with the inorganic silane precursor is preferably selected from silanes containing organic functions, for example of vinyl, epoxy, methacryl oxide, amino nature. In particular, the precursor is selected from: 3- methacryloxypropyl trimethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3- glycidoxypropylethoxysilane, (3-glycidyloxypropyl)trimethoxysilane (GPTMS). Preferably, the organic silane is present in an amount comprised between 2-8%, more preferably between 4-7%.

[0037] The cross-linking agent or hardener for the epoxy resin can be a nucleophile agent, for example of an amino nature such as aliphatic or aromatic amines such as diethylenetriamine, tetraethylenepentamine or polyamides. Particularly suitable polyamines are 1 ,2-ethylenediamine, 1 ,2-propylenediamine, 1 ,3-propylenediamine, 1 ,2- butanediamine, 1 ,3-butanediamine, 1 ,4-butanediamine, 2,3-butanediamine, 2-methyl-1 .3-propanediamine, 2,2-dimethyl-1 ,3-propanediamine, 1 ,3-pentanediamine (DAMP), 1 ,5-pentanediamine, 1 ,5-diamino-2-methylpentane (MPMD), 1 ,6- hexanediamine, 2,5- dimethyl-1 ,6-hexanediamine, 2,2 (4), 4-trimethyl hexamethylenediamine (TMD), 1 ,7- heptanediamine, 1 ,8-octanediamine, 1 ,9-nonanediamine, 1 ,10- decanediamine, 1 - amino-3-aminomethyl-3,5,5-trimethylcyclohexane (isophorone diamine IPDA), 1 ,2- diaminocyclohexane, 1 ,3-diaminocyclohexane, 1 ,4-diaminocyclohexane, 2- or 4-methyl-1 . 3-diaminocyclohexane or mixtures thereof, 1 ,3-bis (aminomethyl) cyclohexane, 1 ,4-bis (amminomethyl) cyclohexane, 2,5 (2,6) -bis (aminomethyl) bicycle [2.2.1 ] heptane (NBDA) , 1 ,4-diamino-2,2,6-trimethyl cyclohexane (TMCDA), 1 ,8-menthane diamine, 1 ,3- bis (aminomethyl) benzene (MXDA), 1 ,4 Bis (aminomethyl) benzene, bis (2- aminoethyl) ether, 3,6-dioxaotane-1 ,8-diamine, 4,7-dioxadecan-1 , 10-diamine, 4,7-dioxadecan-2,9- diamine, 3- (2-aminoethyl) aminopropyl amine, bis (hexamethylene) triamine (BHMT), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), dipropylene triamine (DPTA), N- (2-) Aminoethyl) -1 ,3-propanediamine (N3- amine), N, N'-bis (3-aminopropyl)ethylenediamine (N4-amine), N, N'-bis (3-aminopropyl) -1 ,4-diaminobutane, N5- (3- aminopropyl) -2-methyl -1 ,5-pentanediamine o N3- (3-aminopentyl) -1 ,3-pentanediamine. There may also be used other addition cross-linking agents such as polyacids, polymercaptans and polyphenols, or specifically amine-based photopolymerizable resins, benzyl ether derivatives, hydroxyalkylphenones, a-aminoketones. Preferably, the crosslinking agent is present in an amount comprised between 5-30%, more preferably between 10-20%.

[0038] The alcohol may be selected from methanol, ethanol, 1 -propanol, 2-propanol 2- methyl-2-propanol, cyclohexanol, phenol, butanol, pentanol, hexanol, 2-methoxyethanol, dimethoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-isopropoxyethanol, 2- butoxyethanol, 2-phenoxyethanol, 2-benzyloxyethanol, benzyl alcohol, ethylene glycol. Preferably, alcohol is present in an amount comprised between 2-5%.

[0039] The water is preferably distilled, bi-disti lied or deionised and present in an amount comprised between 1 -6%, more preferably between 2-4%.

[0040] The filler is preferably of carbonaceous nature, for example selected from nanofillers derived from industrial waste products such as carbon black, char, biochar, carbon fibres, or graphite, expanded graphite, graphene, graphene oxide, carbon nanotubes, carbon dots.

[0041] A further filler is nanocellulose, which measures about 100 nm and it has useful characteristics such as high surface-to-volume ratio, high Young's modulus and high tensile strength, low coefficient of thermal expansion, ability to form hydrogen bonds, biocompatibility, eco-compatibility, renewability and non-toxicity. Due to these properties, it can be used in the coating to impart durability, adhesion and stability. Preferably, the filler is present in an amount comprised between 0.05-4%, more preferably between 0.07- 2%.

[0042] The pH regulator is an acid or base that adjusts the pH value of the coating film formation reaction optimally depending on the specific mixed components. The kinetics of hydrolysis and condensation reactions in the sol-gel process depend on several specific parameters, including pH. By changing the pH, that is, by creating acidic or basic conditions, the sol can be destabilized facilitating the formation of the continuous network, affecting its growth and final morphology. A basic environment promotes the formation of more or less spherical particles (with dimensions comprised between 1 -30 nm), branched and with high connectivity to allow the formation of particular aggregates. Acidic conditions, on the other hand, tend to form statistically branched lattice structures withless connectivity. Therefore, the person skilled in the art will be able to choose from time to time which acid or basic substance is best depending on the other components described above. Such regulator will therefore have a pH comprised between 1 and 14, preferably between 1 and 8, more preferably between 1 and 5. In particular, for this purpose, there may be used both a strong acid in aqueous solution at a concentration of 1 -5%wt, among the most common hydrochloric acid, sulfuric acid, nitric acid, and a pure weak acid, such as acetic acid, citric acid, oxalic acid, carbonic acid. Preferably, the regulator is present in an amount comprised between 0.3-0.8%, more preferably between 0.4-0.7%.

[0043] A further object of the invention is a process for the preparation of a nanocomposite dispersion. In particular, the method comprises the following steps in succession: a) mixing inorganic silane precursor, organic silane precursor, alcohol, water by means of a magnetic stirrer at a speed comprised between 50 and 600 rpm for a period of time comprised between 5 and 30 minutes at a temperature comprised between 15 and 30 °C; b) adding acid drop by drop with progressive pH measurement until there is reached a pH comprised between 1 and 14, preferably between 1 and 8, even more preferably between 1 and 5, mixing under the same conditions above and for a period of time comprised between 5 and 50 minutes; c) adding powdered fillers while continuing to mix under the same conditions above and for a period of time comprised between 5 and 30 minutes; d) sonicating the mixture after step c) by means of ultrasonic bath at a power comprised between 20 and 100% for a period of time comprised between 1 and 20 minutes; e) repeating steps c) and d) at least twice; f) adding epoxy monomers or oligomers of natural or recyclable origin by mixing under the same conditions above for 24h; g) adding a cross-linking agent mixing under the same conditions above for a period of time between 1 and 10 minutes.

[0044] The above steps shall be carried out using the substances and their respective amounts of the formulation specified above. In addition, the stirring speeds, temperatures and times described are selected from time to time within the indicated ranges accordingto the characteristics of each specific combination of substances and depending on the common knowledge of the person skilled in the art.

[0045] In particular, it should be noted that in order to achieve the optimum nanometric dispersion, the filler is added to the inorganic silane / organic silane mixture before mixing with the epoxy resin.

[0046] As a matter of fact, it has been observed that the use of different known processes such as polymer intercalation from solution, direct intercalation of the molten polymer (for thermoplastic polymers), direct intercalation by synthesis have a negative impact on the final characteristics of the product in terms of performance, most likely due to the failure to obtain the optimal nanometric dispersion.

[0047] It has been observed that specifically the step for adding the nanomolecular filler prior to adding the epoxy resin somehow allowed an excellent nanometric distribution of the components, which would then facilitate mixing with the resin itself.

[0048] The result of the method is a high-performance anti-corrosive ternary nanocomposite coating, comprising the above formulation. The coating is characterised by being a ternary nanocomposite in which an organic matrix, a nonometric inorganic filler in the form of a sol-gel and an organic filler are combined stably.

[0049] A further object of the invention is a process for the anti-corrosive coating of metal materials comprising the deposition of a film produced based on the formulation and process described above on a metal surface in a single step. In particular, the process comprises the application of the formulation by dip-coating (holding time in the mixture comprised between 2 and 20 minutes), spray coating (spray pressure comprised between 1 and 5 bar), spin coating (rotation speed comprised between 1000 and 12000 rpm) or brush depending on the geometry of the surface to be coated.

[0050] Once applied, regardless of the technique used, the product dries at room temperature creating a soul high performance anti-corrosive film within 24-72h. For applications that allow or need to accelerate the time, the film can be formed by heating to a temperature comprised between 40 and 80°C for a time interval of 1 -3 h. There can be obtained the formation of the coating in a short time also by means of light radiation if the cross-linking is carried out by means of a photoinitiator. The cross-linking, thus the formation of the coating, is carried out by radiation with wavelength radiation comprised in the UV-visible field (200 nm-780 nm) for a period of time comprised between 1 and 6h.

[0051] According to a further object of the invention, a method for the production of a bulk material comprises the aforementioned steps a)-g) followed by a -1000 bar degassingstep (vacuum-venting repetition for at least 2 times) and applied by casting in moulds, with simple or complex geometry depending on the shape intended to be conferred to the finished product. Once applied, the product dries at room temperature in 24-72h. For applications that allow or need to accelerate the time, the bulk can be formed by heating to a temperature comprised between 40 and 80°C for a time interval of 1 - 3h.

[0052] Therefore, yet another object of the invention is a bulk material which can be obtained by means of the formulation described above.

[0053] It should be noted that the combination of the aforementioned components with the respective ranges of amounts in the formulation and the mixing method have resulted in a surprising synergistic effect given that the drawbacks of each of the aforementioned technologies have been overcome. In particular, from the combination of the two prior art technologies based on one polymeric coating and the other on inorganic coating, one would have expected a final result in which the epoxy resin and the inorganic phase could not be combined, that is mixed / dispersed into each other, in a non-perfectly homogeneous way. This results in a clear macroscopic separation between the two phases resulting in a lack of significant interactions which in turn results in increased density, decreased processability, alteration of the impact resistance and surface appearance properties of the polymer. At most, the maximum dispersion can be achieved up to the microscopic level by processes of surface chemical modification of the inorganic material. The surprising and unexpected effect of the combination of the aforementioned components in the formulation and the mixing method is then demonstrated by the experimental data of the embodiments of the invention reported below.

[0054] At this point, using the sol-gel technology, it has been observed that the inorganic nanodomains that are formed are included in the molecular chains. Therefore, the organic-inorganic hybrid that is formed starting from the formulation of the invention results from the close interconnection between the organic and inorganic phases on the nanometric scale. This can be obtained through hydrolysis and condensation chemical reactions that take place in the “sol-gel method”. In particular, starting from low molecular weight precursors (metal alkoxides or derivatives), through hydrolysis and condensation reactions, there is obtained the formation of an inorganic cross-link on a nanometric scale. In conventional composites, on the other hand, the charge has a microscopic size and form factor that varies over a wide range of values: as a matter of fact, there are used particles, strips or fibres.

[0055] Nanocomposites are the result of this specific formulation and its processing process to obtain a new class of materials characterised by ultra-fine phase dispersion, typically in the order of a few nanometres. Due to this dispersion, the nanocomposites are characterised by unique properties not shared by conventional composites or microcomposites and offer new technological and economic opportunities.

[0056] In addition, the use of nanofillers would drastically reduce the amount to be added to the polymer (a maximum of 5-6% by weight of nanofillers compared with percentages greater than 20% by weight of a classic filler), minimising the unwanted effects caused by the addition of the conventional inorganic additives specified above. The nanocomposites are obtained by using nanoparticles, nanofibres, nanotubes, fullerenes, nanolamellas, carbon black, and silica nanoparticles.

[0057] Furthermore, the properties of the nanocomposites are influenced not only by the size of the reinforcement used, but also heavily depend on the degree of mixing of the two phases. Depending on the nature of the materials and the preparation methods used, large differences can be achieved in terms of the properties of the material produced, as explained above.

[0058] Reported below are some examples of some applications of the formulation according to the present invention and comparisons with the properties of the commercial resin.EXAMPLE 1 COATING

[0059] In the present example, the formulation for the production of the anti-corrosive coating of the invention is reported in Table 1 below.TABLE 1

[0060] The formulation of Table 1 has been processed according to the method described in paragraphs

[0037] -

[0038] and in particular: a) mixing in a flask 4 ml of TEOS, 2.5 ml of (3-glycidyloxypropyl)trimethoxysilane, 2 ml of ethyl alcohol, 2 ml of bi-distilled water using magnetic stirrer at 500 rpm for 20 minutes at 17°C; b) adding acetic acid drop by drop with progressive pH measurement until pH 4 is reached under magnetic agitation at a speed of 500 rpm at 17°C for 10 minutes; c) Adding 0.5 g of natural carbon powder to the mixture under magnetic stirring at a speed of 500 rpm at 17°C for 20 minutes; d) sonicating the mixture obtained in step c) with an ultrasonic bath at a power equal to 60% for 10 minutes. e) repeating steps c) and d) at least twice; f) adding 31 ml of epoxy resin under magnetic stirring at 500 rpm at 17°C for 24h; g) adding 7.5 ml of amine under magnetic stirring at 600 rpm at 17°C for 10 minutes. COMPARISON OF WM-A COATING WITH COMMERCIAL RESIN

[0061] Reported below are the main experimental data obtained from the characterisation of the WM-A COATING of the invention, compared with the data obtained on a commercial epoxy resin DGEBA (Bisphenol diglycidyl ether), also used as an anticorrosive coating. Table 2 below shows the analytical data for all properties of WM-A COATING measured and compared to those of commercial epoxy resin-based coatings, which are most commonly used as top-coats in multi-layer anti-corrosive coatings for metals. The data basically shows a lower viscosity of WM-A COATING, thus easier applicability by spraying, brush, or immersion; higher corrosion resistance, greater water repellency and comparable scratch resistance compared to DGEBA. The coating formulation of the invention and the commercial coating formulation were applied by dipcoating (immersion for approximately 15 min) on aluminium, copper and zinc, steel and non-zinc-coated magnesium-based metal alloys. The tests were performed 72 hours after the treatment.

[0062] Water repellency tests (UNI EN 828:2013 Determination by measurement of contact angle and surface free energy of solid surface); tensile test (UNI EN ISO 527- 3:2019 determination of tensile properties - Part 3: Test conditions for films and sheets);scratch resistance (UNI EN 15186:2012 Evaluation of the resistance of surfaces to scratch); electrochemical corrosion resistance (ASTM G5-94 (201 1 ) -Standard Reference Test Method for Making Potentiostatic and Potentiodynamic Anodic Polarization Measurements).

[0063] The electrochemical tests, which provide the current density (measured in mA / cm2) detected on the raw metal sample (aluminium, copper and zinc, steel and magnesium-based metal alloys) treated with WM-A COATING or with commercial epoxy resin (DGEBA) immersed in the electrolyte (NaC1 1 M), allowed to evaluate the exceptional effectiveness of WM-A COATING, given that greater resistance by the coating currents to lower density values. As a matter of fact, if commercial resin has current density values around 8.5mA / cm2, the WM A coating shows current density values <0.5mA / cm2. The corrosion resistance of galvanized and raw samples (without any treatment), which showed a current density of around 25 mA / cm2 and 36 mA / cm2, respectively, was also measured for comparison purposes. This highlights the extraordinary anti-corrosive capacity of the coatings subject of the invention.TABLE 2

[0064] Furthermore, with reference to the graph in Figure 1 , there are compared the recorded current density values for three samples: untreated metal substrate, metal with zinc plating and metal with the coating of the invention (WM-A coating). The test was conducted using a three-electrode cell in an aqueous solution of NaCI at a concentration of 1 m. A platinized titanium electrode was used as a counter electrode and an Ag / AgCI electrode was used as a reference electrode, with respect to which potential values are reported. The working electrode is represented by the sample. Open circuit potential (OCP) measurements were carried out for 60 minutes and potentiostatic polarization measurements were carried out for 60 at a selected potential (-0.8 v).

[0065] Lower current density values correspond to increased resistance to electrochemical corrosion in aqueous NaCI solution. The WM-A coating is found to have excellent electrochemical corrosion resistance showing current density values close to zero.EXAMPLE 2 WM-A BULK

[0066] In the present example, the formulation for the bulk production of a material according to the invention is identical to the one described above with reference to Table 1 . Only the method of application to obtain the finished sample, which is not a film / coating but an object taking the shape of the mould used, changes.

[0067] The formulation was processed according to the method described above with reference to example 1 .

[0068] In accordance with the application methodology described in paragraph

[0044] , the BULK formation was then degassed in a beaker at -1000 bar (repeating a vacuumvent cycle for at least 2 times) and subsequently cast into moulds, both with simple and complex geometry, with thicknesses of about 0.5mm of the bulk layer, at a temperature of around 20°C and with a time to obtain the final bulk sample in 24-72h. In the present example, the shape is a bar.COMPARISON OF WM-A BULK WITH COMMERCIAL RESIN

[0069] Table 3 shows the main experimental data obtained from the characterisation of the invention (WM-A BULK), compared with the data obtained on a commercial epoxy resin DGEBA, also used as bulk system. The liquid product for both mixtures was cast into moulds with standard geometry corresponding to the type of test carried out. Specifically, after 72h, the BULK product for each starting mixture was tested by means of a three-point bend tests (ISO 178 - ASTM D790-2017 3-point bend tests on plastics); thermal tests (differential scanning calorimetry; thermogravimetric analysis); Shore A hardness (ASTM D2240 / 152021 Standard Test Method for Rubber Property — Durometer Hardness).

[0070] The product obtained with the formulation of the invention, WM-A BULK, shows increased mechanical performance, such as for example increased mechanical flexibility, making it easily adaptable to stress, a maximum operating temperature comparable to the commercial resin, and good surface hardness.TABLE 3EXAMPLE 3

[0071] In the present example, the formulation of the invention comprises a synthetic epoxy resin and a synthetic carbonaceous filler. The process for obtaining the final product (both in the form of coating and in the form of bulk) is the same as the one shown in the examples above for WM-A COATING and WM-A BULK. The difference lies in the organic matrix used, in the filler and in the relative amounts of each substance. Therefore, the formulation comprises the following substances present as percentages of the total liquid phase weight of the formulation reported in Table 4:TABLE 4

[0062] According to the method described in paragraphs

[0036] -

[0038] , the formulation relating to Table 4 is processed as follows:- mixing in a flask 10 ml of TEOS, 4.5 ml of (3-glycidyloxypropyl)trimethoxysilane, 3 ml of ethyl alcohol, 4 ml bi-distilled water using a magnetic stirrer at 500 rpm for 20 minutes at 17°C;- adding hydrochloric acid (3%wt solution) drop by drop with progressive pH measurement until pH 4 is reached under magnetic agitation at a speed of 500 rpm at 17°C for 10 minutes;- adding 2.5 g of graphene powder to the mixture under magnetic stirring at a speed of 500 rpm at 17°C for 20 minutes;- sonicating the mixture obtained in step c) with an ultrasonic bath at a power equal to 60% for 10 minutes;- repeating steps c) and d) at least twice;- adding 19ml of resin under magnetic stirring at 600 rpm at 17°C for 24h;- adding 6.5ml of amine under magnetic stirring at 600 rpm at 17°C for 10 minutes.

[0063] On the COATING obtained from the formulation reported in Example 3 and deposited on the metal substrate according to the methodology reported in paragraph 53, there were carried out water repellency tests (UNI EN 828:2013 Determination by measurement of contact angle and surface free energy of solid surface); tensile test (UNI EN ISO 527-3:2019 determination of tensile properties - Part 3: Test conditions for films and sheets); scratch resistance (UNI EN 15186:2012 Evaluation of the resistance of surfaces to scratch); electrochemical corrosion resistance (ASTM G5-94 (201 1 ) - Standard Reference Test Method for Making Potentiostatic and Potentiodynamic Anodic Polarization Measurements). Table 5 shows the results relating to the COATING:TABLE 5

[0064] On the BULK samples obtained from the formulation reported in Example 3 according to the method reported in paragraph

[0044] and in 2 the following tests were carried out: a three-point bend tests (ISO 178 - ASTM D790-2017 3-point bend tests onplastics); thermal tests (differential scanning calorimetry; thermogravimetric analysis); Shore A hardness (ASTM D2240 / 15 2021 Standard Test Method for Rubber Property — Durometer Hardness). Table 6 shows the results relating to the BULK WM-A:TABLE 6EXAMPLE 4 PHOTOPOLYMERIZABLE COATING

[0065] A further example of the invention consists of a photopolymerizable synthetic epoxy resin and a synthesis carbonaceous filler. The method for obtaining the final product (both in the form of coating and in the form of bulk) is the same as the one shown for the WM-A COATING. The difference lies in the organic matrix used, which, being suitable to be photopolymerised, requires an appropriate photoinitiator as a cross-linking agent capable of activating photopolymerization reactions following absorption of light radiation in the UV and visible fields. Therefore, the formulation comprises the following substances present as percentages of the total liquid phase weight of the formulation reported in table 7.TABLE 7

[0066] According to the method described in paragraphs

[0037] -

[0038] , the formulation relating to Table 7 is processed as follows:- mixing in a flask 10 ml of TEOS, 4.5 ml of (3-glycidyloxypropyl)trimethoxysilane, 3 ml of ethyl alcohol, 4 ml of bi-distilled water using magnetic stirrer at 500 rpm for 20 minutes at 17°C;- adding hydrochloric acid (3%wt solution) drop by drop with progressive pH measurement until pH 4 is reached under magnetic agitation at a speed of 500 rpm at 17°C for 10 minutes;- adding 2.5 g of graphene powder to the mixture under magnetic stirring at a speed of 500 rpm at 17°C for 20 minutes;- sonicating the mixture obtained in step c) with an ultrasonic bath at a power equal to 60% for 10 minutes;- repeating steps c) and d) at least twice;- adding 24ml of resin under magnetic stirring at 600 rpm at 17°C for 24h;- adding 1 .5 g of cross-linking agent under magnetic stirring at 600 rpm at 17°C for 10 minutes.

[0067] The previously processed formulation was deposited on a metal substrate according to the methodology reported in paragraph 53 and subsequently activated by UV radiation (350-700 nm) for 30 minutes. The samples were kept in the dark and the tests were carried out 72 hours after the treatment to allow the “dark reaction”, typical of cationic systems whose photopolymerization reaction continues even in dark conditions with an improvement of the properties over time.

[0068] On the COATING obtained with the formulation reported in Example 4 there were carried out water repellency tests (UNI EN 828:2013 Determination by measurement of contact angle and surface free energy of solid surface); tensile test (UNI EN ISO 527- 3:2019 determination of tensile properties - Part 3: Test conditions for films and sheets); scratch resistance (UNI EN 15186:2012 Evaluation of the resistance of surfaces to scratch); electrochemical corrosion resistance (ASTM G5-94 (201 1 ) -Standard Reference Test Method for Making Potentiostatic and Potentiodynamic Anodic Polarization Measurements). Table 8 shows the results relating to the COATING:TABLE 8

[0069] In the light of the above, it is clear that the drawbacks and the limits of the coatings of the prior art have been overcome and significant advantages have been achieved at the same time.

[0070] Firstly, the formulation is completely eco-sustainable, as it does not comprise elements such as chromium that are harmful to the environment and humans. In addition, its application process does not involve the use of toxic solvents.

[0071] Secondly, multiple deposition steps are not required to apply multiple layers in order to achieve the desired efficacy, avoiding the aforementioned drawbacks related to oil-based epoxy resins.

[0072] In addition, the application time compared to polymer multi-layer systems is significantly advantageous given that the application time of at least 3-4 days typically required for primer and resin systems is drastically reduced to 1 -2 days at room temperature, a few hours by means of light radiation or 2 hours with thermal treatment at 60°C, with simple spraying or immersion at room temperature and drying.

[0073] The deposition yield, that is the amount of anti-corrosive product per cm2of surface, in the case of multi-layer products is obtained precisely by combining several layers, whereas with the present invention only one layer is sufficient.

[0074] The greater flexibility of the product that according to the invention results in a lower likelihood of breakage or cracking.

[0075] With respect to zinc plating, there is also the possibility of in-situ repairs even on large surfaces and of repairing any damage or joints of mechanical parts, by applying the product again where necessary, by spraying, after cleaning.

[0076] The possibility to use industrial waste allows recovery and recycling with reduction of industrial waste for a circular economy.

[0077] The fields of application are also very wide and include, for example, pipe coatings for the transport of fuels, both fossil fuels and new generation bio-compatible fuels (biomass) as well as for H2 piping; protective coatings for high voltage components in electric vehicles (batteries for electric vehicles, power distribution units, inverters) or for the electrical grid in general; coatings for pylons and electrical cables in harsh environments; coating of metal parts in marine environments and shipyards; coating for aircraft and helicopter components; constructions and infrastructures; accumulators, batteries, distribution grids, HV piping.

[0078] The formulation and the anti-corrosive coating method of the present invention may be subjected - by a person skilled in the art - to numerous modifications and variants without departing from the scope of protection of the attached claims.

Claims

CLAIMS1. Formulation for the production of a nanocomposite mixture, comprising the following components present as a percentage of the total liquid weight of the formulation:15-85% natural and / or recyclable epoxy monomers or oligomers;5-20% inorganic silane precursor;1 -10% of an organic silane precursor;1 -6% of an alcohol;0.5-8% of water;3-40 % of a cross-linking agent for epoxy monomers or oligomers;0.1 -1 % of a pH regulator;0.01 -6% of a filler,2. Formulation according to claim 1 , wherein said natural epoxy monomers or oligomers are preferably of vegetable oil, carbohydrate, tannic acid, cellulose origin, said recyclable epoxy monomers or oligomers are preferably synthetic selected from aromatic epoxy resins, aliphatic polyepoxides or glycidyl ether cycloaliphatic of saturated or unsaturated, branched or unbranched, cyclic or open chain alcohols C2 -C30, of-, tri- or tetrafunctional C2 -C30, bisphenol liquid resin A, F or hydrogenated A / F, or glycidylation products of bisphenol A, F or -A / F hydrogenated, an N-glycidyl derivative of amides or heterocyclic nitrogenous bases, products of reaction of epichlorohydrin with hydantoin, epoxy resins obtained from the oxidation of olefins, acrylic resins, and combinations thereof.

3. Formulation according to claim 2, wherein said resins are selected from those obtained from methods for epoxidising simple carbohydrates, fatty acids or esters thereof, or saccharides, or phenols and polyphenols, that is natural resins produced by trihydroxybenzoic acid, vegetable resins produced by glycerine-based ligneous extracts, by the bark, flowers or buds of the plants and by lignin and derivatives, that is the vegetable resins produced by resin acids such as abietic acid or dihydroabietic acid or dehydroabietic acid, isosorbide-based natural resins, or vegetable resins produced by itaconic acid, vegetable resins produced by furfural, the resins derived from carbohydrates are selected from those derived from limonene, maltitol, sorbitol and sucrose obtained through etherification methods and subsequent epoxydation, those obtained from the natural fatty acids deriving from soybean oil, coconut oil, sunflower oil, rapeseed oil, palm oil, olive oil, cashew nut shell extract, cardanol, linseed oil, the synthetic ones are glycidylation products of bisphenol A, bisphenolF or bisphenol A / F, where A is acetone and F is formaldehyde, derivatives of dihydroxybenzene, the condensation products of phenols with formaldehyde obtained in acidic conditions, aromatic amines, an N-glycidyl derivative of amides or heterocyclic nitrogenous bases, an N-glycidyl derivative of amides or heterocyclic nitrogenous bases, epoxy resins obtained from the oxidation of olefin.

4. Formulation according to any one of claims 1 to 3, wherein the inorganic silane precursor is an alkoxysilane preferably selected from molecules capable of giving a sol-gel reaction with the organic silane to provide a supporting reticulum such as tetraethoxysilane (TEOS); tetramethoxysilane (TMOS), methyltrimethoxysilane.

5. Formulation according to any one of claims 1 to 4, wherein the organic silane precursor is selected from silanes containing organic functionalities, preferably of a vinyl, epoxy, methacryloxy, amino nature, such as 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3- glycidoxypropylethoxysilane (3-glycidyloxypropyl)trimethoxysilane.

6. Formulation according to any one of claims 1 to 5, where the cross-linking agent is a nucleophile agent, for example of an amino nature such as aliphatic or aromatic amines such as diethylenetriamine, tetraethylenepentamine or polyamides, polyacids, polymercaptans and polyphenols, or specifically of amine-based photopolymerizable resins, derivatives of benzyl ethers hydroxyalkylphenones, a- aminoketones.

7. Formulation according to any one of claims 1 to 6, wherein the filler is a nanofiller derived from industrial waste products such as carbon black, char, biochar, carbon fibres, or graphite, expanded graphite, graphene, graphene oxide, carbon nanotubes, carbon dots, nanocellulose.

8. Method for preparing a nanocomposite dispersion comprising the following steps in succession: a) mixing inorganic silane precursor, organic silane precursor, alcohol, water by means of a magnetic stirrer at a speed comprised between 50 and 600 rpm for a period of time comprised between 5 and 30 minutes at a temperature comprised between 15 and 30 °C; b) adding acid drop by drop with progressive pH measurement until there is reached a pH comprised between 1 and 14, mixing under the same conditions above and for a period of time comprised between 5 and 50 minutes;c) adding powdered fillers while continuing to mix under the same conditions above and for a period of time comprised between 5 and 30 minutes; d) sonicating the mixture after step c) by means of ultrasonic bath at a power comprised between 20 and 100% for a period of time comprised between 1 and 20 minutes; e) repeating steps c) and d) at least twice; f) adding epoxy monomers or oligomers of natural or recyclable origin by mixing under the same conditions above for 24h; g) adding a cross-linking agent mixing under the same conditions above for a period of time between 1 and 10 minutes.

9. Method for the anti-corrosive coating of metal materials comprising the one-step deposition of a film produced based on the formulation on metal surface and the method respectively according to any one of claims 1 to 7 and 8, comprising the application of the dispersion by dip-coating (holding time in the mixture comprised between 2 and 20 minutes), spray coating (spray pressure comprised between 1 and 5 bar.), spin coating (rotation speed comprised between 1000 and 12000 rpm) or brush as a function of the geometry of the surface to be coated.

10. Method for the production of a bulk material, comprising the above steps a) g) according to claim 8 followed by a degassing step at -1000 bar (vacuum-vent repetition for at least 2 times), application by casting in moulds, drying at room temperature in 24-72h.

11. Anticorrosive ternary nanocomposite coating in the form of a sol-gel that can be obtained from a formulation according to any one of claims 1 to 7.

12. Bulk material which can be obtained from a formulation according to any one of claims 1 to 7.

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