Method for treating a metal surface

Abstract

A method for treating a metal surface, wherein the method comprises the steps of: a) preparing a product by mixing a silane-amine intermediate and an epoxydic resin; b) pre-treating the metal surface with the product of step a); c) painting the pre-treated metal surface.

Description

[0001] "Method for treating a metal surface"

[0002] DESCRIPTION

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to a method for treating a metal surface. Particularly, the present invention relates to a method for treating a metal surface in order to increase the resistance of the surface to corrosion.

[0005] BACKGROUND OF THE INVENTION

[0006] Metal surface corrosion presents as exfoliation or surface pitting or a combination of both. Corrosion is defined as an attack on a material as a result of chemical reaction with the surrounding medium. In many instances, corrosion initiates due to adverse environmental conditions, like salt water. Chemical corrosion occurs in an environment where there is no ion conductivity, so usually in the presence of exhaust gases, petroleum, certain organic substances, or gases such as hydrogen, hydrogen sulphide, carbon monoxide (II) or chlorine. Chemical corrosion is sometimes called dry corrosion. Usually, the entire surface of the corroding material comes in contact with the corrosive agent.

[0007] Environmental corrosion occurs in an environment capable of conducting electric charges (in electrolytes) and results in oxidation on metal surfaces and the formation of a brown deposit (rust). It involves an electrochemical reaction that proceeds uniformly over the entire exposed surface of the metal and is responsible for the greatest destruction of metal on a tonnage basis.

[0008] Because of the extent of damage that it can cause, corrosion represents one of the costliest issue faced by many industry sectors.

[0009] Since corrosion cannot be entirely eliminated, all anti-corrosion techniques are aimed to inhibit that process. Coatings are the most popular anticorrosion protection. They are applied by submerging the item in a molten metal (dip immersion) or by metal spraying, which is carried out with a spray gun. Despite applying coatings on a metal surface is an effective procedure to protect the metal surface against corrosion, its success can be limited by the incorrect application, which can compromise the integrity of the coating. Therefore, there remains the need to improve the way to apply the coating on a metal surface.

[0010] SUMMARY OF THE INVENTION

[0011] The present invention relates to a method for treating a metal surface. The method comprises the following steps: a) preparing a product by mixing a silane-amine intermediate and an epoxydic resin; b) pre-treating the metal surface with the product of step a); c) painting the pre-treated metal surface. According to the present invention, the step of pre-treating the metal surface with the product further comprises a step of degreasing the metal surface with a basic solution. The step of pre-treating the metal surface with the product also comprises a step of rinsing the metal surface. The step of pretreating the metal surface with the product further comprises a step of nebulising the product.

[0012] DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention relates to a method for treating a metal surface. The method may comprise a step of preparing a product. The product may be prepared by mixing a silane-amino intermediate and an epoxydic resin. The method may also comprise a step of pre-treating the metal surface with said product. The method may also comprise a step of painting the pre-treated metal surface.

[0014] The term "pre-treatment" indicates the act of treating something beforehand, preliminarily, such that it makes a subsequent process or stage more effective.

[0015] According to the method of the present invention, a silane-amino intermediate may be mixed to prepare the product. According to the method of the present invention, a silane intermediate may undergo a hydrolysis reaction to obtain a silanol. Advantageously, it has been found that the presence of the amine group on the silane increases the capability to hydrolase. It has been shown that the amino group catalyzes the hydrolysis reaction because it creates a basic medium.

[0016] According to some embodiments of the present invention, the silane intermediate may therefore be selected from the group consisting of aminopropyl silane, amino-ethylamine-propylmethoxy silane, and amino- ethylamino-propylethoxy silane.

[0017] Subsequently, according to the method of the present invention, the amino silanol obtained through the hydrolysis reaction may undergo a condensation reaction in order to create a chain of a certain length.

[0018] Preferably, the condensation reaction may be catalyzed using a chelating agent. The chelating agent may be added in an amount of between 0.1% to 10%, between 0.2% to 9.5%, between 0.3% to 9%, between 0.4% to 8.5%, between 0.5% to 8%, between 0.6% to 7.5%, between 0.7% to 7%, between 0.8% to 6.5%, between 0.9% to 6%, between 1% to 5.5%, between 1 .5% to 5%, between 2% to 4.5%, between 2.5% to 4%, between or 3% to 3.5%. More preferably, the chelating agent may be selected from a chelating agent of titanium or zirconium. In some certain embodiments of the present invention, colloidal silica may be further added to the chelating agent. The colloidal silica may be added in an amount of between 1 % to 5%, between 1 .25% to 4.75%, between 1.5% to 4.5%, between 1.75% to 4.25%, between 2% to 4%, between 2.25% to 3.75%, between 2.5% to 3.5%, or between 2.75% to 3.25%.

[0019] Advantageously, it has been shown that the combination of the hydrolysis and condensation reactions may form a grid through the formation of tridimensional structures. In certain specific embodiments of the present invention, such tridimensional structures are called silsesquioxanes. Silsesquioxanes may adopt cage-like or polymeric structures with Si-O-Si linkages and tetrahedral Si vertices. Silsesquioxanes may have a molecular form with 6, 8, 10, 12, or 24 Si vertices, as well as polymers. The cages may present a Si center bonded to three oxo groups, which in turn may connect to other Si centers. Silsesquioxanes may form polyoctahedral silsesquioxanes ("POSS"). Diverse substituents may be attached to the Si centers, such that the POSS may be functionalized.

[0020] According to the method of the present invention, such POSS may react with an epoxydic resin. In particular, the amino group of the silane-amine intermediate POSS may react with the oxydril group of the epoxydic resin. As used herein, the term “epoxydic resin” indicates a monomeric or oligomeric crosslinkable material that possess a reactive functional group, the epoxy or oxirane group. An epoxydic resin as used herein shows chemical and solvent resistance, capability to adhere to a broad range of substrates, fatigue resistance, flexibility, and electrical properties.

[0021] According to some embodiments of the present invention, an epoxydic resin may have a low or high molecular weight. Preferably, the epoxydic resin according to the present invention may have a high molecular weight.

[0022] More preferably, the epoxydic resin according to the present invention may have a molecular weight between 3000 Dalton and 7000 Dalton, between 3100 Dalton and 6900 Dalton, between 3200 Dalton and 6800 Dalton, between 3300 Dalton and 6700 Dalton, between 3400 Dalton and 6600 Dalton, between 3500 Dalton and 6500 Dalton, between 3600 Dalton and 6400 Dalton, between 3700 Dalton and 6300 Dalton, between 3800 Dalton and 6200 Dalton, between 3900 Dalton and 6100 Dalton, between 4000 Dalton and 6000 Dalton, between 4100 Dalton and 5900 Dalton, between 4200 Dalton and 5800 Dalton, between 4300 Dalton and 5700 Dalton, between 4400 Dalton and 5600 Dalton, between 4500 Dalton and 5500 Dalton, between 4600 Dalton and 5400 Dalton, between 4700 Dalton and 5300 Dalton, between 4800 Dalton and 5200 Dalton, or between 4900 Dalton and 5100 Dalton.

[0023] According to some embodiments of the present invention, the epoxydic resin may have a dynamic viscosity between 500 mPa / s and 1500 mPa / s, between 550 mPa / s and 1450 mPa / s, between 600 mPa / s and 1400 mPa / s, between 650 mPa / s and 1350 mPa / s, between 700 mPa / s and 1300 mPa / s, between 750 mPa / s and 1250 mPa / s, between 800 mPa / s and 1200 mPa / s, between 850 mPa / s and 1150 mPa / s, between 900 mPa / s and 1100 mPa / s, and between 950 mPa / s and 1050 mPa / s.

[0024] As used herein, the term “dynamic viscosity” indicates the forces or stresses involved in the deformation of a material. It is the tangential force per unit area required to move one horizontal plane with respect to an other plane - at an unit velocity - when maintaining an unit distance apart in the fluid.

[0025] According to some further embodiment of the present invention, the epoxydic resin may have an epoxy value selected from between 3000 g / mol and 7000 g / mol, between 3100 g / mol and 6900 g / mol, between 3200 g / mol and 6800 g / mol, between 3300 g / mol and 6700 g / mol, between 3400 g / mol and 6600 g / mol, between 3500 g / mol and 6500 g / mol, between 3600 g / mol and 6400 g / mol, between 3700 g / mol and 6300 g / mol, between 3800 g / mol and 6200 g / mol, between 3900 g / mol and 6100 g / mol, between 4000 g / mol and 6000 g / mol, between 4100 g / mol and 5900 g / mol, between 4200 g / mol and 5800 g / mol, between 4300 g / mol and 5700 g / mol, between 4400 g / mol and 5600 g / mol, between 4500 g / mol and 5500 g / mol, between 4600 g / mol and 5400 g / mol, between 4700 g / mol and 5300 g / mol, between 4800 g / mol and 5200 g / mol, or between 4900 g / mol and 5100 g / mol.

[0026] As used herein, the term “epoxy value” indicates the Epoxy Equivalent Weight (EEW) or Weight Per Epoxide (WPE) that is a measure of the epoxy content and corresponds to the number of grams of epoxydic resin required to give one mole of epoxy group. Such epoxy values represent the physical properties of resins such as flexibility, brittleness, permeability, and adhesion.

[0027] According to some embodiments of the present invention, the epoxydic resin may have a oxydril number selected from no more than 200 mg KOH / g, no more than 225 mg KOH / g, no more than 250 mg KOH / g, no more than 275 mg KOH / g, no more than 300 mg KOH / g, no more than 325 mg KOH / g, no more than 350 mg KOH / g, no more than 375 mg KOH / g, no more than 400 mg KOH / g, no more than 425 mg KOH / g, no more than 450 mg KOH / g, no more than 475 mg KOH / g, no more than 500 mg KOH / g, no more than 525 mg KOH / g, no more than 550 mg KOH / g, no more than 575 mg KOH / g, no more than 600 mg KOH / g, no more than 625 mg KOH / g, no more than 650 mg KOH / g, no more than 675 mg KOH / g, or no more than 700 mg KOH / g.

[0028] As used in the present document, the term "oxydril number" indicates the milligrams of potassium hydroxide (KOH) necessary to neutralise the acetic acid that forms during the acetylation of one gram of a chemical substance containing a free hydroxyl group.

[0029] According to some embodiments of the present invention, the epoxydic resin may have a non-volatile content of between 20% and 50%, between 21 % and 49%, between 22% and 48%, between 23% and 47%, between

[0030] 24% and 46%, between 25% and 45%, between 26% and 44%, between

[0031] 27% and 43%, between 28% and 42%, between 29% and 41%, between

[0032] 30% and 40%, between 31% and 39%, between 32% and 38%, between

[0033] 33% and 37%, or between 34% and 36%.

[0034] As used herein, the term “non-volatile content” indicates the quantity of residual soluble, suspended, and particulate matter remaining after the controlled evaporation of a volatile liquid at a specific temperature, to determine the purity of a substance.

[0035] According to some further embodiments of the present invention, the epoxydic resin may have a density of no more than 5 g / cm3, no more than 4.5 g / cm3, no more than 4 g / cm3, no more than 3.5 g / cm3, no more than 3 g / cm3, no more than 2.5 g / cm3, no more than 2 g / cm3, no more than 1.5 g / cm3, no more than 1 .45 g / cm3, no more than 1 .4 g / cm3, no more than 1.35 g / cm3, no more than 1 .3 g / cm3, no more than 1 .25 g / cm3, no more than 1 .2 g / cm3, no more than 1.15 g / cm3, no more than 1.1 g / cm3, no more than 1.09 g / cm3, no more than 1.08 g / cm3, no more than 1.07 g / cm3, no more than 1.06 g / cm3, no more than 1.05 g / cm3, no more than 1.04 g / cm3, no more than 1.03 g / cm, no more than 1.02 g / cm3, no more than 1.01 g / cm3, or no more than 1 g / cm3.

[0036] As used herein, the term “density” indicates the substance’s mass per unit volume.

[0037] According to the present invention, the product may have a silane-amine intermediate to epoxydic resin ratio selected from 1 to 10, from 1 to 9, from 1 to 8, from 1 to 7, from 1 to 6, from 1 to 5, from 1 to 4, from 1 to 3, from 1 to 2, and from 1 to 1.

[0038] According to some further embodiments of the present invention, the product may further comprise a polyol. Preferably the polyol may be a polyether. Advantageously, the polyol may act as rheological addictive through the hydroxyl groups that favors hydrogen bonding. More advantageously, such polyol may improve the flowability and easiness of applicability of the prepared product.

[0039] According to some embodiments of the present invention, the amount of polyol may be selected from 0.1% to 5%, from 0.2% to 4.5%, from 0.3% to 4%, from 0.4% to 3.5%, from 0.5% to 3%, from 0.6% to 2.5%, from 0.7% to 2%, from 0.8% to 1.5%, and from 0.9% to 1%.

[0040] According to some other embodiments of the present invention, the amount of polyol may be no more than 5%, no more than 4.5%, no more than 4%, no more than 3.5%, no more than 3%, no more than 2.5%, no more than 2%, no more than 1.5%, no more than 1%, no more than 0.9%, no more than 0.8%, no more than 0.7%, no more than 0.6%, no more than 0.5%, no more than 0.4%, no more than 0.3%, no more than 0.2%, no more than 0.1%, or no more than 0.05%.

[0041] According to the present invention, the product may be diluted. According to some embodiments of the present invention, the product may be diluted with water. Preferably, according to some embodiments of the present invention, the product may be diluted with demineralized water.

[0042] According to the present invention, the concentration of dilution may be selected from 0.05% to 10%, from 0.1% to 9%, from 0.15% to 8%, from 0.2% to 7%, from 0.25% to 6%, from 0.3% from 5%, 0.35% from 4%, from 0.4% to 3%, from 0.45 to 2%, and from 0.5% to 1 %.

[0043] According to some further embodiments, the concentration of dilution may be no more than 10%, no more than 9.5%, no more than 9%, no more than 8.5%, no more than 8%, no more than 7.5%, no more than 7%, no more than 6.5%, no more than 6%, no more than 5.5%, no more than 5%, no more than 4.5%, no more than 4%, no more than 3.5%, no more than 3%, no more than 2.5%, no more than 2%, no more than 1.5%, no more than 1 %, no more than 0.9%, no more than 0.85%, no more than 0.8%, no more than 0.75%, no more than 0.7%, no more than 0.65%, no more than 0.6%, no more than 0.55%, no more than 0.5%, no more than 0.45%, no more than 0.4%, no more than 0.35%, no more than 0.3%, no more than 0.25%, no more than 0.2%, no more than 0.15%, no more than 0.1%, or no more than 0.05%.

[0044] According to some preferred embodiment of the present invention, there is provided a method for treating a metal surface, wherein the step of pretreating the metal surface with the product may comprise the step of degreasing of the metal surface with a basic solution. The step of pretreating the metal surface with the product may further comprise the step of rinsing the metal surface. The step of pre-treating the metal surface with the product may further comprise the step of nebulizing the product.

[0045] According to some embodiments of the present invention, the metal surface may be selected form the group comprising ferrous alloys from earthen, steel alloys 300 - 400, galvanized alloys, electro-galvanized alloys, hot-dip galvanized alloys, galvanized material, coil, or aluminum alloys.

[0046] According to the present invention, the basic solution for degreasing the metal surface may comprise sodium hydroxide, potassium hydroxide, silicate, carbonate, borate, or alkaline phosphate, or a combination thereof. According to the present invention, the metal surface may be rinsed 4, 3, 2, or 1 time. Preferably, according to the present invention, the metal surface may be rinsed with water. More preferably, according to the present invention, the metal surface may be rinsed with demineralized water.

[0047] Advantageously, according to the present invention, the product may be nebulised.

[0048] According to the present invention, the particles of the nebulised product may have a size that depends on the size of the nebulising nozzle.

[0049] In the present document, the term "nebulising nozzle" indicates a device designed for the purpose of breaking down a liquid into droplets, generating a jet with a defined shape.

[0050] The nebulising nozzle according to the present invention may have an opening ranging from 5 pm to 100 pm, from 10 pm to 95 pm, from 15 pm to 90 pm, from 20 pm to 85 pm, from 25 pm to 80 pm, from 30 pm to 75 pm, from 35 pm to 70 pm, from 40 pm to 65 pm, from 45 pm to 60 pm, or from 50 pm to 55 pm. As a consequence, advantageously, the nebulised particles according to the present invention may have a size of from 1 pm to 50 pm, from 5 pm to 45 pm, from 10 pm to 40 pm, from 15 pm to 35 pm, or from 20 pm to 30 pm. Preferably, the nebulised particles according to the present invention may have a size of from 1 pm to 30 pm.

[0051] According to the present invention, the product may be nebulised, wherein the nebulisation may have a flow of 10 l / h to 500 l / h, 20 l / h to 490 l / h, 30 l / h to 480 l / h, 40 l / h to 470 l / h, 50 l / h to 460 l / h, 60 l / h to 450 l / h, 70 l / h to 440 l / h, 80 l / h to 430 l / h, 90 l / h to 420 l / h, 100 l / h to 410 l / h, 110 l / h to 400 l / h, 120 l / h to 390 l / h, 130 l / h to 380 l / h, 140 l / h to 370 l / h, 150 l / h to 360 l / h, 160 l / h to 350 l / h, 170 l / h to 340 l / h, 180 l / h to 330 l / h, 190 l / h to 320 l / h, 200 l / h to 310 l / h, 210 l / h to 300 l / h, 220 l / h to 290 l / h, 230 l / h to 280 l / h, 240 l / h to 270 l / h, or 250 l / h to 260 l / h. Preferably, the nebulisation may have a flow of between 60 l / h and 250 l / h; more preferably the nebulisation may have a flow of between 60 l / h and 120 l / h.

[0052] According to one embodiment of the present invention, the product may be nebulised by means of a 150 bar to 50 bar high-pressure pump with nozzles that may be made of brass, nickel-plated, stainless steel or aluminium. According to certain other embodiments of the present invention, the product may be nebulised by means of a high-pressure pump of from 145 bar to 55 bar, from 140 bar to 60 bar, from 135 bar to 65 bar, from 130 bar to 70 bar, from 125 bar to 75 bar, from 120 bar to 80 bar, from 115 bar to 85 bar, or from 110 bar to 90 bar.

[0053] More advantageously, it has been found that by nebulizing the product the pre-treating step results in a homogeneous application, particularly when compared with the standard method of application of dip immersion and spray. Such way of applying the product via nebulization allows for the product to reach every part of the metal surface, even the more hindered ones. Even more advantageously, it has also been found that the presence of the rheological additive allows for an even more homogeneous application of the product such that the accumulation in the drainage spots is reduced and the subsequent painting step results in a better adhesion of the paint with less mechanical and aesthetic defects. Surprisingly, it has been found that when the product is applied via nebulization, the entire manufacturing process produces less waste, which consequently allows for a more sustainable process, such that the overspray amount of the nebulized solution can be recovered and reused. More surprisingly, it has been shown that when the metal surface is pretreated with the product of the present invention, the metal surface does not show any degradation sign when undergo accelerated cyclic electrochemical technique (ACET). This was particularly evident when compared to the degradation of the metal surface treated with a silane, that show a decrease in the impedance when subjected to ACET. The Accelerated Cyclic Electrochemical Technique (ACET), which has been adopted as the ISO 17463 standard, allows for the assessment of paints on metal surfaces. The protocol consists of Electrochemical Impedance Spectroscopy (EIS) and Relaxation Voltammetry (RV) to observe the gradual degradation of a coated sample. The test particularly consists in the use of cathodic polarization (CP) as a major stress factor allowing a strong acceleration of failure and the quantitative evaluation of both water uptake and coating adhesion. According to the present invention, it has been demonstrated that both the water uptake and the delta Z (AZ) are close to a value of 0 when the product of the present invention is nebulised onto a metal surface. As used herein, the delta Z indicates the percentage of to what degree the metal surface has degraded from the beginning to the end of the test and a value close to 0 indicates that the surface has not undergone degradation.

[0054] The nebulisation system according to the present invention comprises an external module consisting of a canister of about 200 litres, that allows for continuous feeding of the product to be sent to the outlets, for the nebulisation of a predefined volume. Such system allows all the volume that is not nebulized to fall and be collected in a tank ready to be relaunched and reused through a pump. Advantageously, the tank of the system is construed such the product never gets in contact with pollutants such that the composition of the product is maintained of the same quality for each nebulization cycle.

[0055] Advantageously, while recovering the product for the reusage, the process allows for an automatic cleaning that guarantees a more effective management of the rinsing tubs.

[0056] According to the method of the present invention, the volume of nebulised product may be between 1 and 200 l / h, between 5 and 190 l / h, between 10 and 180 l / h, between 15 and 170 l / h, between 20 and 160 l / h, between 25 and 150 l / h, between 30 and 140 l / h, between 35 and 130 l / h, between 40 and 120 h / l, between 45 and 110 l / h, between 50 and 100 l / h, between 55 and 90 l / h, or between 60 and 80 l / h.

[0057] According to some embodiments of the present invention, the nebulised volume of the product may be no more than 200 l / h, no more than 195 l / h, no more than 190 l / h, no more than 185 l / h, no more than 180 l / h, no more than 175 l / h, no more than 170 l / h, no more than 165 l / h, no more than 160 l / h, no more than 155 l / h, no more than 150 l / h, no more than 145 l / h, no more than 140 l / h, no more than 135 l / h, no more than 130 l / h, no more than 125 l / h, no more than 120 l / h, no more than 115 l / h, no more than 110 IZh, no more than 105 l / h, no more than 100 l / h, no more than 95 l / h, no more than 90 l / h, no more than 85 l / h, no more than 80 l / h, no more than 75 l / h, no more than 70 l / h, no more than 65 l / h, no more than 60 l / h, no more than 55 l / h, no more than 50 l / h, no more than 45 l / h, no more than 40 l / h, no more than 35 l / h, no more than 30 l / h, no more than 25 l / h, no more than 20 l / h, no more than 15 l / h, no more than 10 l / h, or no more than 5 l / h.

[0058] According to the present invention, the pre-treated metal surface may be painted with liquid or powder paint. According to some certain embodiments of the present invention, the metal surface may be painted with liquid paints selected from polyester paints, polyurethane paints, epoxy paints, acrylic paints, vinyl paints, or epoxy-polyester paints. Preferably, according to the present invention, the pre-treated metal surface may be painted with a polyester liquid paint. According to other embodiments of the present invention, the metal surface may be painted with powder paints selected from polyester paints, or epoxydic paints.

[0059] The present invention relates also to a substrate that may comprise two layers, wherein one layer may comprise a product comprising a silaneamino intermediate and an epoxydic resin; and the other layer may comprise a paint.

[0060] The present invention also relates to the use of a product that may comprise a silane-amino intermediate and an epoxydic resin for the treatment of a substrate, preferably a metal surface.

[0061] The present invention is further described but not limited to the following examples.

[0062] EXAMPLES

[0063] Example 1

[0064] The following metal surfaces were used for the tests:

[0065] ® Iron alloys; • Galvanised iron alloys;

[0066] • Aluminium alloys.

[0067] For the tests, all the metal surfaces were pre-treated with a product comprising gamma-aminopropyl silane, polysilicic acid (silanol), and high- molecular-weight epoxydic resin.

[0068] The pre-treatment was carried out via nebulisation using nebulising nozzles with a flow of 60 - 120 l / h.

[0069] The following tests were performed: o Neutral salt spray (NSS);

[0070] • Acetic acid salt spray (AASS).

[0071] The metal surfaces used for the NSS and AASS tests were painted with polyester powder paint, with and without cataphoresis.

[0072] The following tests were performed by way of comparison:

[0073] « accelerated cyclic electrochemical technique (ACET);

[0074] ® electrochemical impedance spectroscopy / l inear polarisation resistance (EIS / LPR).

[0075] The metal surfaces used for the ACET test were painted.

[0076] The metal surfaces used for the EIS / LPR test were not painted.

[0077] For the NSS and AASS tests, each metal surface underwent a cross engraving having an acute angle of 30°C, thickness 0.5 - 1 mm and length of maximum 10 cm. Post-tests evaluation was performed by applying jets of compressed air (3 - 5 Bar) along the entire length of the engraving followed by a tear test that used adhesive tape according to ISO 2409.

[0078] For the NSS and AASS tests, a 5% aqueous solution of NaCI (sodium chloride) was used. For the AASS test, a pre-defined amount of acetic acid was also added to ensure that the pH of the solution was between 3.0 and 3.1.

[0079] The results consisted in the evaluation of the proper functioning of the corrosion chamber by collecting the solution sprayed inside the chamber and by evaluating the weight loss of the metal surfaces. The results were collected after the maximum numberof hours when the maximum measured detachment of 2+2 mm was reached and after which the test was stopped. The results are shown in the Table 1 .

[0080] Table 1

[0081] For the EIS / LPR test, electric current was measured by varying the electrochemical potential.

[0082] During the tests, the following values were monitored:

[0083] - Jcorr (current density) expressed in A / cm2

[0084] - Corrosion rate expressed in mm / year

[0085] - Rp (polarisation resistance) expressed in ohms (0).

[0086] For the ACET test, a 3-electrode cell was used and the impedance values and the Bode diagram were evaluated.

[0087] The test lasted 24 hours, during which the following three steps were repeated six times:

[0088] 1. EIS

[0089] 2. Cathodic Polarization at -4V for 20 minutes

[0090] 3. Relaxation Voltammetry for 180 minutes.

[0091] For the ACET test, a 3.5% aqueous solution of NaCI was used. The samples, contrary to the NSS and AASS tests, were not engraved.

[0092] During the tests, the following values were monitored:

[0093] - maximum impedance value (Z) measured from the beginning to the end of the test, expressed in (Q*cm2);

[0094] - minimum impedance value (Z) measured from the beginning to the end of the test, expressed in (Q*cm2)

[0095] - AZ, which represents the percentage of degradation of the metal surface from the beginning to the end of the test;

[0096] - water uptake, which represents the percentage of water absorbed by the coating.

[0097] The results are gathered together in Tables 2, 3, 4, 5, 6, 7, 8, 9.

[0098] Table 2

[0099] The results refer to the NSS and AASS tests carried out on iron alloys, prepared as described above. The data are expressed in mm of delamination.

[0100] Table 3

[0101] The results refer to the NSS and AASS tests carried out on galvanised iron alloys, prepared as described above. The data are expressed in mm of delamination.

[0102] Table 4

[0103] The results refer to the NSS and AASS tests carried out on aluminium alloys, prepared as described above. The data are expressed in mm of delamination.

[0104] Table 5

[0105] The results refer to the EIS / LPR tests carried out on iron alloys, prepared as described above. Table 6

[0106] The results refer to EIS / LPR tests carried out on galvanised iron alloys, prepared as described above.

[0107] Table 7

[0108] The results refer to ACET tests carried out on galvanised iron alloys, prepared as described above.

[0109] Table 8

[0110] The results refer to ACET tests carried out on galvanised iron alloys, prepared as described above.

[0111] Table 9 The results refer to ACET tests carried out on aluminium alloys, prepared as described above.

Claims

CLAIMS1. A method for treating a metal surface, wherein the method comprises the steps of: a. Preparing a product by mixing a silane-amine intermediate and an epoxydic resin; b. Pre-treating the metal surface with the product of step a); c. Painting the pre-treated metal surface.

2. The method according to claim 1 , wherein the product has a silaneamine intermediate to epoxydic resin ratio selected from 1 to 10, from 1 to 9, from 1 to 8, from 1 to 7, from 1 to 6, from 1 to 5, from 1 to 4, from 1 to 3, from 1 to 2, and from 1 to 1 .

3. The method according to claims 1 or 2, wherein the product further comprises a polyol, preferably wherein the polyol is a polyether.

4. The method according to claim 3, wherein the amount of polyol is selected from 0.1 % to 5%, from 0.2% to 4.5%, from 0.3% to 4%, from 0.4% to 3.5%, from 0.5% to 3%, from 0.6% to 2.5%, from 0.7% to 2%, from 0.8% to 1.5%, and from 0.9% to 1%.

5. The method according to any preceding claim, wherein the product is diluted with demineralized water.

6. The method according to claim 5, wherein the concentration of dilution is selected from 0.05% to 10%, from 0.1 % to 9%, from 0.15% to 8%, from 0.2% to 7%, from 0.25% to 6%, from 0.3% from 5%, 0.35% from 4%, from 0.4% to 3%, from 0.45 to 2%, and from 0.5%7. The method according to any preceding claim, wherein the step b) of pre-treating the metal surface comprises the steps of: a. Degreasing of the metal surface with a basic solution; b. Rinsing the metal surface; c. Nebulizing the product.

8. The method according to claim 7, wherein the basic solution comprises sodium hydroxide, potassium hydroxide, silicate, carbonate, borate, or alkaline phosphate, or a combination thereof.

9. The method according to claims 7 and 8, wherein the metal surface is rinsed 4, 3, 2, or 1 time.

10. The method according to the claim 9, wherein at least one of the rinse is performed with demineralized water.

11. The method according to claims 7 to 10, wherein the nebulized volume of product is between 1 to 200 l / h, between 5 to 190 l / h, between 10 to 180 l / h, between 15 to 170 l / h, between 20 to 160 l / h, between 25 to 150 l / h, between 30 to 140 l / h, between 35 to 130 l / h, between 40 to 120 h / l, between 45 to 110 l / h, between 50 to 100 l / h, between 55 to 90 l / h, or between 60 to 80 l / h.

12. The method according to claims 7 to 11, wherein the pre-treated metal surface is painted with a liquid paint or a powder paint.

13. A substrate comprising two layers, wherein one layer comprises a product comprising a silane-amino intermediate and an epoxydic resin; and the other layer comprises a paint.

14. Use of a product comprising a silane-amino intermediate and an epoxydic resin for the treatment of a substrate, preferably a metal surface.

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