Aqueous dispersion anti-corrosion protective coating composition

Abstract

The present invention relates to an aqueous dispersed particulate metal-based anticorrosive protective coating composition for metal parts, the composition comprising a monomer mixture consisting of silane, at least one silicate and at least one titanate.

Description

Technical Field

[0001] The present invention relates to an aqueous dispersed particulate metal-based anti-corrosion protective coating composition for metal parts, the composition comprising a monomer mixture consisting of a silane, at least one organic silicate and at least one titanate. Background Art

[0002] Recent environmental concerns have driven products across various application areas to reduce their carbon footprint. It's widely acknowledged that waterborne zinc-rich flake coatings offer a more environmentally friendly profile than 100% solvent-based products. However, to achieve comparable anti-corrosion performance, they must be cured at temperatures of 310°C, while solvent-based products only require a curing temperature of around 240°C, significantly increasing carbon emissions. Furthermore, the international energy landscape, particularly rising energy prices and fuel shortages, is driving industry to re-evaluate production processes and shift towards solutions that consume increasingly less energy.

[0003] Patent application number EP1713869 filed by Dacral relates to a water-dispersible, particulate, metal-based corrosion protection coating composition for metal parts. This composition contains titanium and / or an aqueous or organic-compatible organic zirconate, possibly a silane-based binder, and water. However, its curing temperature must reach 310°C to achieve good corrosion protection. If satisfactory mechanical properties are to be achieved at lower curing temperatures, the composition must be further improved. Furthermore, the sol-gel binder has an insufficient crosslinking speed and density, resulting in insufficient film density at 220°C, which results in substandard corrosion protection.

[0004] Patent application number US4224213 filed by COOK PAINT & VARNISH CO. relates to the use of alkyl silicates and alkyl titanates to achieve a zinc-rich protective coating. In this patent, the composition is water-free, and the film is formed by crosslinking monomers using atmospheric moisture as a reaction initiator.

[0005] Patent application number KR101541046 filed by Zincotec covers a zinc-rich protective coating composed of silane, titanate, alkaline silicate, water, and particulate metal. The coating composition contains only 20.9% to 35% water, and its curing temperature must reach 310°C to achieve good corrosion protection. Similarly, if satisfactory mechanical properties are to be achieved at a lower curing temperature, the composition must be further improved. Furthermore, the crosslinking speed and density of the sol-gel binder are not satisfactory. Furthermore, even with controlled water content, achieving low volatile organic compound (VOC) levels and long-term stability in the liquid composition is difficult.

[0006] Therefore, there is a need for a product that is produced in a low-pollution manner, contains a small amount of volatile organic compounds (VOCs), and can maintain its anti-corrosion performance through its sacrificial protection characteristics. Summary of the Invention

[0007] After years of effort, the inventors have unexpectedly succeeded in producing a water-dispersible, granular, metal-based anti-corrosion protective coating composition for metal parts. This composition has a lower ecological impact than existing protective coating compositions because it can produce a protective coating requiring a curing temperature below 310°C while maintaining its anti-corrosion properties. Furthermore, the composition according to the present invention contains a minimal amount of cosolvent, resulting in a volatile organic compound (VOC) content of less than 7%, preferably less than 5%.

[0008] The present invention relates to the use of a water-based organo-mineral sol-gel adhesive in which the ratio of silane / silicate / titanate monomers enables crosslinking at low temperatures while maintaining a long adhesive life. This ratio corresponds specifically to a 2:1:1 silane / silicate / titanate ratio, more specifically, a slightly higher content of silicate than titanate. The formulation parameters and raw materials can be optimized to achieve a formulation with minimal volatile organic compounds (VOCs) (<7%), crosslinking below low temperatures (220°C), and cathodic protection of the film at the same 220°C curing temperature for corrosion protection. The formulation can be free of methanol and raw materials containing carcinogenic, mutagenic, or reprotoxic (CMR) substances.

[0009] Therefore, compared to existing commercially available compositions, the present invention can lower the curing temperature of corrosion protection coating compositions for metal parts by 90°C, significantly reducing energy consumption and process costs. These systems can also be equipped with lower-power curing ovens, reducing investment in these equipment. The amount of volatile organic compounds (VOCs), particularly degradation products, released is significantly reduced (VOC content is reduced from approximately 25% to below 7%, preferably below 5%). Consequently, this has a very positive ecological and economic impact. Implementation Method

[0010] The present invention relates to an aqueous dispersed granular metal-based anti-corrosion protective coating composition for metal parts, wherein the composition comprises the following components in the following proportions (by weight):

[0011] - 2% to 50% of a monomer mixture, wherein the monomer mixture comprises a silane, at least one silicate and at least one organic titanate;

[0012] - between 10% and 40% of at least one particulate metal or a mixture of particulate metals;

[0013] - Water: replenish to 100%;

[0014] Wherein, the monomer mixture comprises the following components in proportions (percentage by weight):

[0015] - silane in an amount between 40% and 70% by weight, preferably between 40% and 60% by weight, more preferably between 50% and 60% by weight;

[0016] - between 10% and 40% by weight, preferably between 15% and 30% and more preferably between 20% and 30% by weight of at least one silicate; and

[0017] - 10% to 40% by weight, preferably 15% to 30% by weight, more preferably 15% to 25% by weight of at least one titanate.

[0018] The silicate is preferably a non-alkaline silicate.

[0019] The silicate may be or contain an organosilicate of the formula Si(OR)4, wherein R1, R2, R3 and R4 each independently represent an optionally substituted C1-C8 alkyl group, preferably tetraethoxysilane (TEOS), of the formula Si(OEt)4. Therefore, in this context, tetraethoxysilane (TEOS) is considered a silicate rather than a silane. In alternative embodiments containing a mineral silicate mixed with an organosilicate, the proportion of the organosilicate is significantly higher than the proportion of the mineral silicate.

[0020] The titanate may be selected from the group consisting of organic phase compatible organotitanates and aqueous phase compatible organotitanates.

[0021] In the context of the present invention, the term "organic phase-compatible titanate" is intended to mean any organic titanate that is incompatible with water, ie highly reactive in aqueous compositions and sensitive to humidity and water (hydrolysis reaction).

[0022] In the present invention, the term "water-compatible titanate" refers to any water-compatible titanate, i.e., a titanate that is soluble, emulsifiable, or dispersible in aqueous compositions. These are typically organic titanates stabilized by chelation. They are also known as "chelated (organic) titanates." Organic-compatible organic titanates can be used in anhydrous compositions as catalysts, crosslinkers, surface treatment agents, adhesion promoters, or preservatives.

[0023] The organic phase compatible titanate is preferably a tetraalkyl titanate having C1-C8 residues, which can be represented by the following molecular formula (I):

[0024] [Chemical Formula 1]

[0025] Wherein, R1, R2, R3 and R4 independently represent an alkyl group of C1-C8, which may be substituted. The tetraalkyl group of C1-C8 titanate is preferably selected from tetraethyl titanate (TET, Ti(OC2H5)4), tetrabutyl titanate (TET, Ti(OC2H5)4), tetrabutyl titanate (TET, Ti(OC2H5)4), tetraethyl ... n BT, Ti(OC4H9), tetraisopropyl titanate (TPT, Ti[(OCH(CH3)2]4) and octanediol titanate (OGT, TI(O2C8H 17 )4), and a group consisting of mixtures thereof.

[0026] Organic phase compatible organic titanates can also be in the form of chelated organic titanates that are incompatible with water. AA (titanium acetylacetonate) and The product DC (diisopropyl bis(ethyl acetoacetate) titanate) can be taken as an example of a chelated form of an organic titanate that is incompatible with water (compatible with organic phases).

[0027] The water-compatible titanate is preferably a chelated titanate, which can be represented by the following general formula (II):

[0028] [Chemistry 2]

[0029] Where R and R' represent a C1-C 10 Alkyl (which may be substituted), X and X' independently represent a functional group containing an oxygen or nitrogen atom, Y and Y' independently represent a hydrocarbon chain containing 1 to 4 carbon atoms. X and X' preferably represent an amino group or lactate.

[0030] The organic titanate in chelated form compatible with the aqueous phase is preferably selected from triethanolamine titanate (sold by Dorf Ketal TE and TEP). The name sold by Dorf Ketal is TA (chelated form of alcoholamine titanate) and LA (titanate and lactic acid chelate) products are examples of organic titanates in a chelated form that is compatible with the aqueous phase.

[0031] In some embodiments, the organic titanate is selected from the group consisting of tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and mixtures thereof, preferably selected from the group consisting of tetraethyl titanate (TET).

[0032] The particulate metal or mixture of particulate metals of the protective coating composition can be selected from the group consisting of metallic pigments such as aluminum, manganese, nickel, titanium, stainless steel, zinc, alloys thereof, and mixtures thereof. The particulate metal is preferably selected from zinc and aluminum, alloys thereof, mixtures thereof, or alloys thereof with manganese, magnesium, tin, or silicon.

[0033] The particulate metal present in the composition is preferably in powder form and has different homogeneous or heterogeneous geometric structures, in particular spherical, lamellar, lens-shaped or other specific shapes. The particle size of the particulate metal is preferably less than 100 μm, more preferably less than 40 μm.

[0034] When the particulate metal is an alloy or mixture of zinc and aluminum, the aluminum content can, if desired, be very small, such as only 0.1% to 5% by weight of the particulate metal, while still providing a protective coating having a lustrous appearance.

[0035] The protective coating composition should contain no more than about 40% particulate metal by weight of the total composition to maintain the optimal appearance of the protective coating and should contain at least 10% particulate metal by weight of the composition to provide a glossy protective coating.

[0036] The metal can be formulated in small amounts or as a paste in one or more solvents, such as dipropylene glycol and / or white spirit, particularly when the metal is prepared in a layered form. Typically, the particulate metal with the solvent is in a paste form and can be applied directly to the other components of the composition. However, the particulate metal can also be used in a dry form in the protective coating composition.

[0037] The silane preferably contains a functional group with at least one hydrolyzable hydroxyl group, which should be selected from alkoxy radicals in the C1-C4 range, preferably alkoxy radicals in the C1-C2 range. The silane preferably has three functional groups that can be hydrolyzed into hydroxyl groups, preferably three identical functional groups.

[0038] Silanes may also have epoxy (ethylene oxide) functional groups which may promote crosslinking and adhesion to the substrate. "Hydrolyzable to hydroxyl functional groups" refers to all chemical functional groups that are capable of reacting with water to be converted into hydroxyl -OH functional groups.

[0039] Silanes act as binders in the monomer mixture of the present invention to improve the adhesion and corrosion resistance of the protective coating.

[0040] The silane is part of a monomer mixture comprising 2% to 50% of the composition according to the invention, preferably comprising between 40% and 70% by weight of the total weight of the monomer mixture, preferably between 40% and 60% by weight, more preferably between 50% and 60% by weight.

[0041] The silane is preferably readily dispersible in aqueous media and preferably soluble in such media after hydrolysis. The silane used is preferably an epoxy-functional silane selected from epoxy-functional dimethoxysilane or trimethoxysilane or epoxy-functional diethoxysilane or triethoxysilane, and mixtures thereof, in particular γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexane)ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane or 4-(trimethoxysilyl)butane-1,2-epoxide.

[0042] The liquid medium of the protective coating composition is almost always water or a combination of water and an organic solvent. Other solvents may be used, but are preferably used in minimal amounts. Typically, the composition contains water in an amount of 28% to 65% by weight based on the total weight of the composition.

[0043] According to a suitable alternative embodiment of the present invention, the protective coating composition further comprises an organic solvent or a mixture of multiple organic solvents in an amount of 1% to 7%, preferably 1% to 5%, based on the total weight of the composition. Thus, the amount of volatile organic compounds (VOCs), especially degradation products, released is very limited.

[0044] The organic solvent is preferably selected from the group consisting of glycol solvents, such as glycol ethers, in particular diethylene glycol, triethylene glycol and dipropylene glycol, acetates, propylene glycol, polypropylene glycol, nitropropane, alcohols, ketones, propylene glycol methyl ether, 2,2,4-trimethylpentanediol monoisobutyrate (alcohol ester film-forming aid), white spirit, and mixtures thereof. Dipropylene glycol is particularly advantageous, particularly in terms of economics and environmental protection.

[0045] When the metal particles are prepared in a lamellar form in a solvent, the resulting particulate metal may be in the form of a paste, which may form part of the organic solvent of the composition according to the invention.

[0046] According to a suitable alternative, the protective coating composition further contains one or more corrosion inhibiting pigments, such as aluminum triphosphate or aluminum polyphosphate, phosphates, molybdates, zinc silicate, strontium silicate, calcium silicate, barium silicate, zirconium silicate and mixtures thereof, the weight of the corrosion inhibiting pigments accounting for 0.2% to 4% of the total weight of the protective coating composition.

[0047] The protective coating composition according to the present invention may also contain a thickener. The thickener is preferably selected from the group consisting of cellulose derivatives, such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, cellulose acetate butyrate, xanthan gum, associative thickeners of the polyurethane or acrylic type, silica, silicates, such as magnesium and / or lithium silicates, which may have been treated, or organoclays, and mixtures thereof. The thickener is preferably present in an amount of less than 7% by weight of the composition, more preferably between 0.005% and 7% by weight of the composition.

[0048] The protective coating composition according to the present invention may further comprise one or more wetting agents, preferably in an amount less than 4% by weight of the composition, and preferably between 0.1% and 4% by weight of the composition, relative to the total weight of the composition. The wetting agent is preferably selected from C11 to C20 fatty alcohol alcoholates, such as fatty alcohol methoxylates, fatty alcohol ethoxylates, and fatty alcohol propoxylates, and C8 to C12 alkyl glycosides, such as D-pentose alkyls, D-glucose alkyls, and polyglycoside alkyls.

[0049] The protective coating composition according to the present invention may further comprise one or more antifungal agents, preferably comprising less than 4% by weight of the total composition, and more preferably between 0.05% and 4% by weight of the composition. The antifungal agent is preferably selected from the group consisting of polysiloxanes and polyethersiloxanes.

[0050] The protective coating composition according to the present invention may also include one or more pH adjusters, preferably present in an amount less than 4% by weight of the composition, and preferably between 0.05% and 4% by weight of the composition, relative to the total weight of the composition. The pH adjuster is preferably selected from oxides and hydroxides of alkali metals (preferably lithium and sodium), and oxides and hydroxides of metals belonging to Groups IIA and IIB of the Periodic Table, such as compounds of calcium, barium, magnesium, and zinc. The pH adjuster may also be a carbonate or nitrate of a noble metal. The pH adjuster may also be selected from amines, such as triethylamine, methyldiethylamine, methyldiethanolamine, and dimethylethylamine.

[0051] The protective coating composition according to the present invention may further comprise one or more passivating agents, preferably in an amount less than 4% by weight of the composition, preferably between 0.1% and 4% by weight of the composition, compared to the total weight of the composition.

[0052] The composition of the present invention may further contain phosphates, phosphorus-containing substitutes, such as aluminum triphosphate and iron phosphate (pigment), and inorganic salts, the weight of which accounts for less than 3% of the weight of the composition.

[0053] The present invention also relates to a process for producing the protective coating composition. The process comprises the following steps:

[0054] (a) preparing an adhesive by adding silane, organic silicate and titanate into an aqueous solution;

[0055] (b) reducing the rate of alcohol produced during evaporation by compensating with the addition of water; and

[0056] (c) adding metal particles and additives to the composition obtained in step (b).

[0057] In another embodiment, the manufacturing process includes the following steps:

[0058] (a) preparing an adhesive by adding silane, organic silicate and titanate into an aqueous solution;

[0059] (b) preparing a solvent composition containing metal particles and additives; and then

[0060] (c) adding the composition obtained in step (a) to the composition obtained in step (b) and allowing the composition obtained in step (b) to fully dissolve.

[0061] The present invention also relates to applying the protective coating composition according to the present invention on a substrate by spraying, dipping-draining or dipping-centrifuging to obtain a protective coating, and then curing the protective coating by providing thermal energy, such as by thermal convection, infrared or induction. This step is preferably completed in the temperature range of 180°C to 250°C, and more preferably in the temperature range of 180°C to 220°C. When thermal energy is provided by thermal convection or infrared, this step must last for 10 to 60 minutes, or when thermal energy is provided by induction, this step must last for 30 seconds to 5 minutes.

[0062] According to a suitable embodiment, the anti-corrosion protective coating is generated by a relevant application operation before the curing operation, and then the metal part to which the protective coating composition is applied is dried by applying heat energy (for example, by convection, infrared or induction), with the drying temperature being between 30°C and 250°C, preferably around 70°C. When the heat energy is provided by convection or infrared, the drying operation should last for 10 to 30 minutes, and when the heat energy is provided by induction, the drying operation should last for about 30 seconds to 5 minutes. In most cases, it is recommended to remove foreign matter from the substrate surface before applying the protective coating, mainly by careful cleaning and degreasing.

[0063] Under these conditions, the dry film thickness of the protective coating applied in this way is between 3 μm (approximately 11 g / m2 ) and 30μm (about 110g / m 2 ), preferably between 4 μm (about 15 g / m 2 ) and 12μm (about 45g / m 2 ), more preferably between 5 μm (about 18 g / m 2 ) and 10μm (about 40g / m 2 )between.

[0064] The invention can also be extended to metallic substrates, preferably steel, galvanized steel or steel coated with a zinc base layer deposited by different application methods including mechanical deposition, cast iron and aluminum, to provide them with an anticorrosion protective coating according to the invention obtained using the above-mentioned composition.

[0065] The metal substrate may be pretreated, for example with chromates or phosphates, etc. Thus, the substrate may be pretreated to obtain a protective coating of 0.1 to 1 gram per square meter of iron phosphate or 1.5 to 4 grams per square meter of zinc phosphate.

[0066] The invention also relates to the use of the composition according to the invention as a corrosion protection coating for metal parts.

[0067] The present invention also relates to an aqueous composition consisting of a monomer mixture comprising a silane, at least one silicate and at least one titanate, which is used to prepare the aqueous dispersed particulate metal-based protective coating composition for metal parts according to the present invention, comprising (in weight percentage):

[0068] - between 0% and 7% by weight, preferably between 0% and 5% by weight, of a water-soluble organic solvent;

[0069] - silane in an amount between 40% and 70% by weight, preferably between 40% and 60% by weight, more preferably between 50% and 60% by weight;

[0070] - between 10% and 40% by weight, preferably between 15% and 30% and more preferably between 20% and 30% by weight of at least one silicate; and

[0071] - 10% to 40% by weight, preferably 15% to 30% by weight, more preferably 15% to 25% by weight of at least one titanate;

[0072] - Water: replenish to 100%; BRIEF DESCRIPTION OF THE DRAWINGS

[0073] [ Figure 1Corrosion performance of commercially available protective coatings. AS IS = Parts directly subjected to the salt spray test (BS) according to ISO 9227; CTV = Mechanical damage caused by five drops from a height of 1 meter plus a vibratory bowl feed at approximately 100 Hz for 5 minutes prior to the salt spray test (BS); CTH = Thermal shock at 180°C for 96 hours prior to the salt spray test (BS). Rating @5 = No red rust was observed during the salt spray test. Rating @4.8 = During the salt spray test, one of the five test samples tested exhibited a red rust rate between 0.1% and 5%.

[0074] [ Figure 2 ]: Anti-corrosion performance of the anti-corrosion protective coating composition according to the present invention. AS IS (as is) = Parts directly subjected to the salt spray test (BS) according to ISO 9227 standard; CTV = Mechanical damage caused by 5 drops from a height of 1 meter + 5 minutes of vibrating bowl feeding before the salt spray test (BS); CTH = Thermal shock at a temperature of 180°C for 96 hours before the salt spray test (BS). ACT: Cyclic corrosion resistance test according to the manufacturer standard "STD423-0014" of VOLVO. Score @5 = No red rust was observed during the salt spray test. Score @4.8 = During the salt spray test, one of the five test samples subjected to the salt spray test had a red rust rate between 0.1% and 5%. DETAILED DESCRIPTION

[0075] Example

[0076] Example 1: Properties of the composition according to the present invention

[0077] The formulations of layered zinc type anti-corrosion protective coating compositions for metal parts currently sold on the market, e.g. When cured at 310°C, it has very good corrosion resistance even after mechanical damage and after 4 days of thermal shock at 180°C (salt spray resistance in accordance with ISO9227 - salt spray test>>720 hours). However, when cured at temperatures below or equal to 220°C, the corrosion resistance will decrease (see Figure 1 The inventors concluded that the performance degradation of these formulations after curing at 220°C is related to their chemical composition, primarily the binder content. Furthermore, these formulations may contain high levels of volatile organic compounds (VOCs).

[0078] The usage ratios of various raw materials in the current market are summarized as follows:

[0079] [Table 1] A B C Silane 9.9 13.8 12.2 Titanate 3.8 4.3 4.3 Silicate (tetraethoxysilane) 0.0 0.7 0.9 additive 4.7 5.0 4.8 corrosion inhibitors 1.7 1.9 1.9 water 40.9 46.4 36.8 solvent 13.5 2.3 14.3 zinc 22.4 23.9 21.8 aluminum 3.2 1.6 3.0

[0080] The composition according to the present invention is a choice of raw materials with very low levels of volatile organic compounds (VOCs) and a specific choice of monomers that form a sol-gel network through polycondensation. Surprisingly, this sol-gel network achieves sufficient crosslinking density at low temperatures (220°C) to effectively penetrate the layered zinc particles in the film and promote electron circulation within the protective coating. If excessive crosslinking occurs, removing the binder can significantly reduce the barrier effect of the film and allow the electrolyte to penetrate too quickly, without leaving time for corrosion mechanisms, including the sacrificial effect of zinc.

[0081] The monomers used to synthesize the sol-gel binder in the examples cited herein include 3-glycidoxypropyltriethoxysilane, tetraethoxysilane (TEOS) and tetraethyl titanate (TET), with the following proportions:

[0082] [Table 2]

[0083] As in Figure 2 As shown in , the examples of the composition according to the present invention show that it has better corrosion protection performance than the existing composition which is cured at a temperature of only 220°C.

[0084] The results showed that the coating showed good performance on the screw substrate, with a coating weight of 27-33 g / m2 after application, and maintained this performance after mechanical damage. After a thermal shock test at 180°C for 4 days, the performance level decreased slightly, but the corrosion resistance was still maintained for about 800 hours.

[0085] In the ACT cycle test (cyclic corrosion test according to VOLVO's manufacturer standard "STD423-0014"), no loss of salt spray resistance was found after mechanical and thermal shock: a performance improvement of more than 100% was found between the AS IS (as is) system and mechanical damage (CVT) + thermal shock (CTH).

[0086] Additives such as metallic aluminum can also have a positive impact on salt spray performance.

[0087] like Figure 2 As shown in the results of the present study, the addition of aluminum (Examples 2 and 3) improves the corrosion resistance of the product (salt spray (BS)), especially after thermal shock, without significantly affecting the viscosity of the product, while also modulating the activity of the upstream zinc. These observations can be verified by electrochemistry (potentiokinetics).

[0088] From the results, it is clear that a 2:1:1 ratio of silane / silicate / titanate gives surprising results, unlike the ratios of previous examples presented in the art, which are quite different from the ratios presented in the present invention.

Claims

1. A water-based dispersed granular metal-based anti-corrosion protective coating composition for metal parts, comprising the following components in the following proportions (by weight): - 2% to 50% of a monomer mixture, wherein the monomer mixture comprises a silane, at least one silicate and at least one organic titanate; - between 10% and 40% of at least one particulate metal or a mixture of particulate metals; - Water: replenish to 100%; It is characterized in that the monomer mixture contains the following components in proportions (weight percentage): - 40% to 70% by weight, preferably 40% to 60% by weight, more preferably 50% to 60% by weight of said silane; - between 10% and 40% by weight, preferably between 15% and 30% and more preferably between 20% and 30% by weight of said at least one silicate; and - a weight percentage of between 10% and 40%, preferably between 15% and 30%, more preferably between 15% and 25% of the at least one titanate.

2. The composition according to claim 1, characterized in that The monomer mixture comprises the following components in proportions (by weight): - a weight percentage of between 40% and 60%, preferably between 50% and 60%, of said silane; - between 15% and 30% by weight, more preferably between 20% and 30% by weight, of the at least one silicate; and - a percentage by weight of between 15% and 30%, more preferably between 15% and 25%, of said at least one titanate.

3. The composition according to any one of claims 1 to 2, characterized in that The at least one silicate is an organic silicate of formula Si(OR)4, wherein R1, R2, R3 and R4 each independently represent an optionally substituted C1-C8 alkyl group, preferably tetraethoxysilane (TEOS) of formula Si(OEt)4.

4. The composition according to any one of claims 1 to 3, characterized in that The particulate metal is selected from zinc and aluminum, their alloys and mixtures thereof, or their alloys with manganese, magnesium, tin or silicon.

5. The composition according to any one of claims 1 to 4, characterized in that The silane comprises a silane having at least one hydrolyzable functional group to form a hydroxyl group, wherein the hydrolyzable functional group is selected from C1-C4 alkoxy groups.

6. The composition according to any one of claims 1 to 5, characterized in that The silane is selected from a dimethoxysilane or trimethoxysilane having an epoxy group or a diethoxysilane or triethoxysilane having an epoxy group, and mixtures thereof, in particular γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexane)ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane or 4-(trimethoxysilyl)butane-1,2-epoxide.

7. The composition according to any one of claims 1 to 6, characterized in that The titanate is selected from tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and preferably tetraethyl titanate (TET).

8. The composition according to any one of claims 1 to 7, characterized in that The composition further comprises an organic solvent or an organic solvent mixture in an amount of 1% to 7% by weight, preferably 1% to 5% by weight (relative to the total weight of the composition).

9. An anti-corrosion protective coating for metal parts, characterized in that: The protective coating is prepared by spraying, dipping-draining or dipping-centrifuging the protective coating composition according to any one of claims 1 to 8, and then curing the coating by inputting thermal energy, for example, by convection, infrared or induction heating, preferably at a temperature between 180°C and 250°C, more preferably between 180°C and 220°C, for about 10 to 60 minutes by convection or infrared heating, or for 30 seconds to 5 minutes by induction heating.

10. Use of the composition according to any one of claims 1 to 8 as an anti-corrosion protective coating for metal parts.

11. An aqueous composition of a monomer mixture, wherein the monomer mixture comprises a silane, at least one silicate and at least one titanate, for preparing an aqueous dispersed particulate metal-based protective coating composition for metal parts according to any one of claims 1 to 8, comprising the following components in the following proportions (by weight): - between 0% and 7% by weight, preferably between 0% and 5% by weight, of a water-soluble organic solvent; - silane in an amount between 40% and 70% by weight, preferably between 40% and 60% by weight, more preferably between 50% and 60% by weight; - between 10% and 40% by weight, preferably between 15% and 30% and more preferably between 20% and 30% by weight of at least one silicate; - between 10% and 40% by weight, preferably between 15% and 30% and more preferably between 15% and 25% by weight of at least one titanate; and - Water: Replenish to 100%.

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