WO2022023685A1

WO2022023685A1 - Composition and use of this composition for forming a sol-gel coating on a metal surface

Info

Publication number: WO2022023685A1
Application number: PCT/FR2021/051430
Authority: WO
Inventors: Sylvain MARC
Original assignee: Arcane Industries
Priority date: 2020-07-31
Filing date: 2021-07-30
Publication date: 2022-02-03
Also published as: FR3113059B1; FR3113059A1

Abstract

The present invention relates to a composition for forming a sol-gel coating on a metal surface, to the use of this composition for forming a sol-gel coating for improving the corrosion resistance and adhesion of a metal surface composed of any type of metals, to a process for preparing the composition, and to a kit for preparing the composition.

Description

Title of the invention: Composition and use of this composition for the formation of a sol-gel type coating on a metal surface

Technical area

The present invention relates to the field of sol-gel type coatings on a metal surface which may be composed of any type of metal. More specifically, the present invention relates to a composition for the formation of a sol-gel type coating on a metal surface, the use of this composition for the formation of a sol-gel type coating to improve the resistance to corrosion and adhesion of a metal surface composed of any type of metal, a method for preparing the composition according to the invention and a kit for preparing the composition according to the invention.

The present invention finds its application in various fields in which there are parts whose metal surface is composed of all types of metals, which require anti-corrosion protection by application of an organic coating and / or improvement of the adhesion of the coating. organic. Reference can be made, for example, to the railway, naval, automotive, aeronautical, building, architecture fields.

State of the art

In the fields of transport such as the railway, automobile and aeronautical fields, the parts having a metallic surface are subjected during their use to a corrosive environment composed in particular of water, oxygen and various ions. The metal parts most often used in these fields are made of ferrous or non-ferrous metals.

Various anti-corrosion strategies and/or strategies for improving the adhesion of parts whose surface or the whole of the part is composed of non-ferrous metals have been proposed in the prior art, based on the application of one or more layers of a protective composition on the surface of said part. Reference may in particular be made to the application to said surface of a solution comprising hexavalent (Cr(VI)) or trivalent chromium as anti-corrosion agent.

However, due to the potential carcinogenic effects of hexavalent chromium and the negative effects for the environment linked to the implementation of compositions comprising this compound, which require the use of a large quantity of sometimes toxic organic solvents and water , its use is now strictly regulated in Europe by the REACH Directives and in the United States by the Environmental Protection Agency (EPA), and tends to be prohibited. Thus, alternative solutions had to be developed.

Among these alternative solutions, reference may be made to US Pat. No. 6,579,472 from the Boeing company, which describes a sol-gel solution comprising an organometallic salt, an organosilane, one or more compounds having a borate, zinc or phosphate function, preferably the triethylphosphate (0=P(0C H ₅ ) ₃ ), and an organic acid such as acetic acid as catalyst. This document indicates that this composition, after application, has anti-corrosion and adhesion-improving properties for metal surfaces composed of aluminum or titanium only.

US Patent 6,605,365 describes a solution for producing a sol-gel film on a metal surface, said solution comprising a stabilized alkoxyzirconium compound, such as tetra-i-propoxy-zirconium or tetra-n-propoxyzirconium and a organosilane coupling agent, such as 3-glycidoxypropyltrimethoxysilane or a corresponding primary amine, acetic acid as a catalyst, and water. This document recommends applying several layers of this composition to the metal surface. The composition proposed in this document makes it possible to obtain a limited anti-corrosion effect and only on metal surfaces composed of non-ferrous metals such as aluminum or other stainless metals. This composition therefore does not make it possible to obtain a significant anticorrosion effect on a metal surface composed of any type of metal and in particular of ferrous metals.

Thus, the solutions proposed in the prior art have low anticorrosive properties, described rather as accessories in comparison to the improvement of adhesion, and these properties are limited to the surface of metal parts composed of aluminum or alloys. metal comprising aluminum and / or magnesium, and / or titanium or composed of stainless metals. These solutions therefore do not make it possible to effectively prevent and/or reduce corrosion on a metal surface composed of any type of metal, in particular ferrous metals such as carbon steel, while improving the adhesion of said surface, in particular to organic coatings.

In fact, the compositions intended for the formation of a sol-gel film, which are generally acidic, are very sensitive and their stability can be easily altered by the nature of the compounds present, by the pH, by the concentration of the compounds present, by the nature of the active species such as a source of zirconium or else by the drying conditions after application. This is why the addition of components in addition to those necessary for the formation of a sol-gel film is often avoided so as to maintain a stable composition and make it possible to obtain a homogeneous, dense and low-permeability sol-gel film. . For example, anti-corrosion agents which are often alkaline in nature or of a metal-binding nature, tend to complex the active species, in particular a source of zirconium and to destabilize it, as well as to increase the pH of the composition. The consequences can be the precipitation of the active species and/or in fine the modification of the three-dimensional network of the sol-gel film to be formed and therefore of its properties/performances relating to corrosion and adhesion.

To form a thin and dense film necessary for good adhesion and the anticorrosion barrier effect, the sol-gel solutions are preferably acidic in nature. However, the application of such compositions to ferrous and corrosion-sensitive metals immediately leads to the rapid formation of rust (known as “flash rusting”), making the application of an organic coating impossible and the surface unusable. When the solutions are basic, the material formed during the evaporation of the solvent is less adherent and more porous for this type of application. Thus, to date there is no solution of sol-gel type, in particular acid, for promoting adhesion and anti-corrosion properties, in particular on ferrous metals.

The few sol-type compositions described in the prior art in which anti-corrosion agents have been added are most of the time not very stable over time so that they are no longer usable or at least have diminished properties after 24 hours after preparation. These compositions must therefore be prepared shortly before their implementation. These unstable compositions lead to the formation of an inhomogeneous, sparse and permeable coating or film whose properties of resistance to corrosion and improvement of adhesion conferred on the surface to which they are applied are reduced. Other solutions have been proposed in the prior art to improve the adhesion and to prevent and/or reduce the corrosion of a metal surface composed of ferrous metals, one can for example refer to phosphating treatments. However, these techniques require complex installations, the implementation of restrictive monitoring, high energy consumption and generate waste for which a treatment chain must be set up. As regards the improvement of the adhesion to the organic coatings of the surface of a metal part composed of ferrous metals, mechanical treatments have been proposed such as sanding, abrasion by sandblasting of the surface. However, these techniques are also restrictive to implement, require high energy and labor consumption and also produce waste.

Thus, there is a need to have a composition for the formation of a coating of the sol-gel type which is stable, in particular over a period of time greater than 24 hours, and which makes it possible to easily form a thin film, dense, stable, homogeneous, of low porosity and conferring high anti-corrosion properties, on a metal surface composed of any type of metal and in particular of ferrous metals, in particular providing an improvement in the adhesion of this surface in particular to organic coatings.

There is also a need to have a composition for forming a sol-gel type coating on a metal surface composed of any type of metal which is stable, easy to implement, inexpensive, environmentally friendly. environment.

Finally, there is a need to have a composition for forming a coating on a metal surface composed of any type of metal which is simple and quick to implement, while respecting the environment and whose implementation work can be easily integrated into existing surface treatment processes without requiring major modifications or the installation of complex installations.

Summary of the invention

The Applicant has noticed that it is possible to have a composition for forming a coating of the sol-gel type on a metal surface composed of any type of metal, which gives said surface both properties high in terms of corrosion resistance but also improved adhesion vis-à-vis organic coatings in particular.

To do this, the Applicant proposes, according to a first object, an aqueous composition free of chromate for the formation of a coating of the sol-gel type, comprising a source of zirconium, an organosilane, an anticorrosion compound, an alcohol containing a acetylenic acid, a quaternary ammonium salt and a polyamine. A second object of the invention relates to the use of the composition defined above for the formation of a sol-gel type coating on a metal surface.

A third object of the invention relates to a method for preparing said composition.

Description of the invention

For the reasons indicated above, it is desirable to be able to have a composition for the formation of a sol-gel type coating having high anticorrosion properties as well as better adhesion to organic coatings to a metal surface composed of all types of metals. It is with this in mind that the Applicant has developed a composition meeting these specifications.

The present invention therefore relates, according to a first object, to an aqueous composition free of chromate for the formation of a coating of the sol-gel type, comprising a source of zirconium, an organosilane, an anticorrosion compound, an alcohol containing an acetylenic function, a quaternary ammonium salt and a polyamine.

The composition proposed by the Applicant is advantageously stable, easy to implement, inexpensive, respectful of the environment and allows the formation of a sol-gel type coating on a metal surface composed of any type of metal, in particular ferrous metals, which is stable, homogeneous, dense, thin, of low porosity and conferring high anti-corrosion properties on said surface as well as improved adhesion in particular to organic coatings.

The composition provided by the invention has good stability over time, in particular for several weeks after its preparation, preferably from 24 hours to 6 weeks, more preferably from 24 hours to 2 weeks, thus allowing easier and deferred implementation if necessary with respect to the time when it is manufactured unlike the compositions of the prior art. The composition proposed by the invention also makes it possible to have a single and same solution making it possible to improve not only the resistance to corrosion but also the adhesion of any metal surface without having recourse to chemical treatments of the phosphating type or to treatments mechanics such as sanding or shot-blasting, each of which has the aforementioned drawbacks such as difficulties in implementation, restrictive monitoring, production of waste, etc. The present invention thus advantageously provides a universal chemical treatment making it possible to confer on a metallic surface composed of any type of metal, high properties of resistance to corrosion and of improvement of adhesion in particular to an organic coating.

In the following description, the different embodiments of the invention and the different aspects of these embodiments can be combined with one another.

In the context of the present invention, the term “aqueous composition” means a composition which comprises at least 70% by weight of water.

The term “free of chromate” means the fact that the composition does not comprise deliberately added chromate; the composition may however comprise up to 0.1% by mass of chromate originating from the various reagents used to prepare the composition.

The term "sol-gel", a contraction of "solution-gelling", designates a series of reactions in which a soluble metal species (typically a metal alkoxide or a metal salt) hydrolyzes to form a metal hydroxide. Soluble metal species usually contain suitable organic ligands to match the resin in the bonded structure. The metal hydroxides formed condense in solution to form an organic/inorganic hybrid polymer. Depending on the reaction conditions, the metallic polymers can condense into colloidal particles or expand to form a network gel.

In the context of the present invention, the term "sol-gel type coating" or "sol-gel type film" or even "xerogel" is used to refer to the product obtained after application of the composition according to the invention to the surface. one-piece metal. The sol-gel type coating or film according to the invention comprises a hybrid three-dimensional network of metal oxides of zirconium and functionalized silicon, is stable, homogeneous, of low porosity and of low thickness.

Preferably, the sol-gel type film formed on the surface of a part has a thickness comprised between 5 nanometers and 5 micrometers, preferably between 20 nanometers and 1 micrometer and more preferably between 50-300 nanometers.

The term "metallic surface composed of all types of metals" means a metallic surface composed in whole or in part of ferrous metals of non-ferrous metals, of ferrous and/or non-ferrous metal alloys, of precious metals or of a mixture of some of these materials. One can for example refer in a non- exhaustive and limited to iron, steel, cast iron, galvanized steel, aluminum and alloys, copper, bronze, brass and alloys or stainless metals such as stainless steel, titanium, nickel, precious metals (platinum, palladium, rhodium, gold and silver) or mixtures of some of these metals. Preferably, the metallic surface targeted by the present invention is composed wholly or partly of ferrous metals, sensitive to corrosion, such as iron, steel, cast iron and preferably of ferrous metals comprising less than 2.0% by mass carbon such as extra-soft steels (whose carbon content is less than 0.1% by mass), so-called soft steels (whose carbon content is 0.1% to 0.2% by mass) , medium-soft steels (with a carbon content of >0.2% to 0.3% by mass), medium-hard steels (with a carbon content of >0.3% to 0.4 % by mass), hard steels (whose carbon content is >0.4% to 0.5% by mass), or even extra-hard steels (whose carbon content is >0.5% at 2.0% by mass). According to a particular aspect, the metallic surface considered in the present invention is not composed of non-ferrous metals, is not made of stainless steel, is not made of aluminum or titanium.

The present invention can be applied equally to a part of which one or more surfaces is composed of metals of any type or else of which one or more surfaces as well as the rest of the part is composed of metals of any type, or else whose whole part is made of metals of any type.

In the context of the present invention, the term “anti-corrosion property” or even “anti-corrosion effect” or “corrosion resistance” is understood to mean the ability of the composition according to the invention to prevent and/or reduce, diminish the appearance of corrosion on the metal surface of a part made of any type of metal after application of the composition to said surface. This property can be evaluated by the visual detection of the appearance of points or areas of corrosion on the metal surface, characterized by an orange, red, ocher color. The ability of the composition according to the invention to improve the corrosion resistance conferred by an organic coating on the surface of a part composed of metals of any type can also be evaluated by performing a so-called "salt spray" test, for example. .

The term "improve adhesion" is understood to mean the ability of the composition according to the invention to improve or increase the adhesion of the metal surface of a part after application of the composition to said surface, in particular to a coating organic, for example of the paint type or adhesives of epoxy nature. This capacity can for example be evaluated by carrying out a so-called “pull-off traction” test or “crossover test” characterized in that the composition is applied to the metal surface of a part, followed by a drying time. in ambient air for approximately 30 minutes to 24 hours, followed by the application of an organic paint-type coating, followed by a drying step for a time determined according to the type of coating applied, followed by the " traction pull-off” or “cross fit test”. For the “pull-off traction” test (standard in ISO 4624-2003) it consists of sticking a stud on the paint, trimming the stud then exerting a force to tear off the stud. The measurement of the force necessary to tear off the stud and the tearing profile (cohesive, adhesive, mixed) characterizes the adhesion of the paint on the support.... For the "cross cut test" (EN ISO 2409 standard 2007), depending on the thickness of the paint, a claw is used to square the paint, then using a piece of tape, the squared area is glued and then torn off. The condition of the scratches and the number of squares removed are then evaluated to characterize the adhesion of the paint according to a reference system.

The composition according to the present invention advantageously makes it possible to improve the adhesion of the metal surface of a part for different types of coatings, in particular organic coatings, the nature of the binders of which may, for example, be of the epoxy, polyurethane, alkyd, polyester type. , vinyl, diol and polyol, acrylate, glycerophthalic. Among the organic coatings, mention may be made, for example, of liquid paints, powder paints, glues, adhesives, mastics.

As indicated above, the composition according to the invention is a chromate-free aqueous composition for forming a sol-gel type coating, comprising a source of zirconium, an organosilane, an anticorrosion compound, an alcohol containing a acetylenic acid, a quaternary ammonium salt and a polyamine. The composition according to the invention is a composition of the sol type for the formation of a coating or film of the sol-gel type on a metal surface. The composition according to the present invention has an acidic pH, preferably a pH in the range of 2.0 to 6.0 and more preferably a pH in the range of 3.0 to 5.0. The pH is adjusted if necessary within the range of values mentioned above using an organic acid, for example acetic acid.

According to one embodiment, the source of zirconium present in the composition according to the invention is chosen from ammonium zirconium carbonate, hexafluorozirconic acid, zirconium acetate, zirconium carboxylate, zirconium propoxide, zirconium n-butoxide, zirconium oxalate, zirconium glycolate, ammonium zirconium lactate, ammonium zirconium citrate, zirconium nitrate or a mixture of between them. Preferably the source of zirconium is chosen from zirconium acetate, zirconium carboxylate, zirconium oxalate or a mixture of them. More preferably, the source of zirconium is zirconium acetate.

According to one embodiment, the composition according to the invention comprises from approximately 0.1% to approximately 10% by mass, preferably from approximately 0.5% to approximately 5.0% by mass, of zirconium source (by relative to the total mass of the composition).

According to one embodiment, the organosilane present in the composition according to the invention is chosen from 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldiisopropylethoxysilane, 3-glycidoxypropyldiisopropylmethoxysilane, (3-glycidoxypropyl) methyldiethoxysilane, 2- (3,4 epoxycyclohexyl) ethyl triethoxysilane, 3-mercaptopropyltrimethoxysilane, 3- mercaptopropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3 methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, the allytriméthoxysilane, the 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, n-phenylaminopropyltrimethoxysilane, p- or m-aminophenylsilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane or a mixture thereof. Preferably, the organosilane is chosen from 3-glycidoxy-propyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, (3-glycidoxypropyl)methyldiethoxysilane or a mixture of them. More preferably, the organosilane is 3-glycidoxypropyltrimethoxysilane.

According to one embodiment, the composition according to the invention comprises from approximately 0.1% to approximately 10% by mass, preferably from approximately 0.5% to approximately 5.0% by mass of organosilane (relative to to the total mass of the composition).

According to one embodiment, the anticorrosion compound is chosen from an acetate, borate, citrate, molybdate, nitrate, phosphate, plumbate, silicate or phosphate of one of the following elements: aluminium, ammonium, antimony, silver, barium, bismuth, boron , cadmium, calcium, cerium, cesium, chromium, cobalt, copper, dyprosium, europium, gallium, germanium, indium, iron, lanthanum, lead, lithium, magnesium, manganese, molybdenum, neodymium, nickel, potassium, praseodymium, rubidium, samarium , silicon, sodium, strontium, tellurium, terbium, thallium, uranium, yttrium and zinc, or a mixture of the aforementioned salts. Preferably, the anti-corrosion compound is an acetate, borate, molybdate, phosphate, nitrate or silicate of one of the following elements: ammonium, aluminum, silver, barium, calcium, cerium, cadmium, cobalt, copper, dysprosium, lead, lithium, magnesium, potassium, praseodymium, silicon, sodium, strontium, uranium, yttrium and zinc, or a mixture of the aforementioned salts. More preferably, the anticorrosion compound is chosen from an acetate or nitrate of chromium, cerium, yttrium, praseodymium, zinc, or a mixture of these salts. Very particularly preferably, the anticorrosion compound is chosen from zinc acetate, cerium nitrate or a mixture of these salts.

According to one embodiment, the composition according to the invention comprises from approximately 0.05% to approximately 5% by mass, preferably from approximately 0.1% to 2.0% by mass of anticorrosion compound (relative to the total mass of the composition).

According to a particularly preferred embodiment, the composition according to the invention comprises from 0.5% to 2.0% by mass of anti-corrosion compound (relative to the total mass of the composition).

According to one embodiment, the alcohol containing an acetylenic function (that is to say a compound containing both an alkyne function and at least one alcohol function) comprises from 3 to 12 carbon atoms. Preferably, said alcohol containing an acetylenic function is chosen from l-propyn-3-ol, l-butyn-3-ol, l-pentyn-3-ol, l-hexyn-3-ol, 1- hep tyn-3-ol, l-octyn-3-ol, l-nonyl-3-ol, l-decyn-3-ol, 1- phenyl-2-propyn-l-ol, 2- phenyl-3-butyn-2-ol, 2-methyl-l-pentyn-3-ol, 3-methyl-l-nonyn-3-ol, ethynylcyclohexanol, methylbutynol, 2-butyn-l, 4-diol, 2-methyl-3-butyn-2-ol, 2,5-dimethyl-3-hexyn-2,5-diol, 2,5-diphenyl-3-hexyne-2,5-diol , benzylbutynol, 4-ethynyl-benzyl alcohol, ethynyl-2,4,6-trimethylbenzyl alcohol, 5-decyne-4,7-diol, 4-ethyl-l-octyn-3-ol, 2-propyn-l-ol (propargyl alcohol), or mixtures thereof. More preferably, the alcohol containing an acetylenic function is propargyl alcohol.

According to one embodiment, the quaternary ammonium salt is chosen from a salt, preferably a chloride, of dialkyldimethylammonium or of alkyldimethylalkylbenzylammonium, each of these "ammonium" having a CrC ₃₀ alkyl chain, preferably C ₃ -C ₂₅ , and more preferably C ₆ -C ₂ 2 · Preferably, the quaternary ammonium salt is cocoalkyl dimethylbenzyl ammonium chloride. According to one embodiment, the polyamine is a tetramine such as hexamethylenetetramine.

According to one embodiment, the alcohol containing an acetylene function, the quaternary ammonium salt and the polyamine are used in a combined amount of about 0.1% to about 2% by weight, preferably about 0. 1% to about 1.0% by weight, based on the total weight of the composition.

In one embodiment, the composition according to the invention may also comprise an alcoholic solvent. The latter is advantageously chosen from methanol, ethanol, isopropanol, butanol, monomethyl propylene glycol, butyl glycol or a mixture of them. Preferably the alcoholic solvent is isopropanol or ethanol. The alcoholic solvent makes it possible to promote, if necessary, the dissolution of the source of zirconium and of the organosilane during the preparation of the composition and the wetting and drying during application.

According to one embodiment, the composition according to the invention comprises from approximately 0.1% to approximately 10.0% by mass, preferably from approximately 0.1% to approximately 5.0% by mass, more preferably from about 1.0% to about 5.0% by weight of alcoholic solvent (relative to the total weight of the composition) when the latter is present.

According to one embodiment, the composition according to the invention may also comprise a surfactant, which may be a nonionic, anionic or cationic surfactant or a mixture of them. Preferably, the surfactant is a nonionic surfactant, in particular a derivative of ethylene glycol and/or propylene glycol with or without a fatty or fluorinated chain, such as polyethylene glycol mono perfluoroalkyl ether, perfluoroalkyl ethers of polyalkylene glycol. Advantageously, the surfactant is a polyethylene glycol mono perfluoroalkyl ether.

According to one embodiment, the composition according to the invention comprises from approximately 0.1% to approximately 2.0% by mass, preferably from approximately 0.1% to approximately 1.0% by mass of surfactant (by relative to the total mass of the composition) when the latter is present.

It will have been understood that the composition is mainly composed of water which represents at least 70% by mass, for example at least 80% by mass, at least 85% by mass, or even at least 90% by mass, of the total mass of the composition. In other words, water represents 100% balance of the sum of the other constituents of the composition. Thus, according to one embodiment, the composition according to the invention comprises:

- about 0.1% to about 10% by mass, preferably about 0.5% to about 5.0% by mass of zirconium source;

- approximately 0.1% to approximately 10% by mass, preferably approximately 0.5% to approximately 5.0% by mass of organosilane;

- approximately 0.05% to approximately 5% by mass, preferably approximately 0.1% to 2.0% by mass of anti-corrosion compound;

- about 0.1% to about 2% by weight, preferably about 0.1% to about 1.0% by weight of a mixture (alcohol containing an acetylenic function + quaternary ammonium salt + polyamine);

- optionally, approximately 0.1% to approximately 10.0% by mass, preferably approximately 0.1% to approximately 5.0% by mass of alcoholic solvent;

- optionally, approximately 0.1% to approximately 2.0% by mass, preferably approximately 0.1% to approximately 1.0% by mass of surfactant;

- the balance being 100% made up of water.

According to a particularly preferred aspect of this embodiment, the composition comprises from 0.5% to 2.0% by mass of anti-corrosion compound (relative to the total mass of the composition).

According to one embodiment, in the composition according to the invention, the source of zirconium is zirconium acetate; the organosilane is 3-glycidoxypropyltrimethoxysilane; the anti-corrosion compound is zinc acetate, cerium nitrate or a mixture of these compounds; the alcohol containing an acetylenic function is propargyl alcohol, the quaternary ammonium salt is cocoalkyl dimethylbenzyl ammonium chloride; and the polyamine is hexa methylene tetramine. When present, the surfactant is preferably a polyethylene glycol mono perfluoroalkyl ether, and the alcoholic solvent, when present, is preferably ethanol or isopropanol.

According to one embodiment, the composition according to the present invention may also comprise additives for rheology and a dyestuff chosen from dyes, pigments, nacres. The presence of rheological additives makes it possible to adapt the product according to the mode of application (spray or bath) and a coloring material within the composition advantageously makes it possible to ensure that its application is uniform on a metal surface. A second object of the present invention relates to the use of a composition according to the first object of the invention for the formation of a sol-gel type coating on a metal surface composed of any type of metals in which said composition is applied to the metal surface and then dried at room temperature. In the context of the present invention, the composition can for example be applied one or more times, preferably only once.

The use according to the present invention advantageously makes it possible to form on a metallic surface a coating of the sol-gel type or even a film of the sol-gel type which is stable, homogeneous, of low porosity, of low thickness and giving said surface high properties of resistance to corrosion and adhesion in particular to organic coatings.

The composition can be dried at a temperature between about 15 and about 35°C, preferably at a temperature between about 20 and about 30°C, more preferably the composition is dried at a temperature of about 25°C. The drying time of the composition varies according to the drying temperature and can be between about 15 minutes and about 5 hours, preferably between about 30 minutes and about 1 hour 30 minutes, more preferably the composition is dried for about 1 hour.

The present invention thus advantageously provides a composition which does not require a drying step at a high temperature after application to a metal surface in order to obtain the desired anti-corrosion properties. This thus makes it possible to limit the costs linked to the use of the composition, to be able to easily use the composition according to the invention but also to be able to easily implement the use of this composition within an already existing industrial process.

In particular, in the use according to the invention, the composition can be applied to the metal surface by spraying, by roller application, by spin coating, by application of impregnated wipes or by brush application or by immersion in a bath comprising said composition, preferably by spraying.

More particularly, in the use according to the invention, the metal surface is composed of at least one metal chosen from a ferrous metal, a non-ferrous metal, a ferrous and/or non-ferrous metal alloy, or a precious metal.

For example, reference can be made in a non-exhaustive and limiting manner to iron, steel, cast iron, galvanized steel, aluminum and its alloys, copper, bronze, brass and its alloys or stainless metals such as stainless steel, titanium, nickel, precious metals (platinum, palladium, rhodium, gold and silver) or mixtures of one or more of these metals. Preferably, the metallic surface targeted by the present invention is composed wholly or partly of ferrous metals, sensitive to corrosion, such as iron, steel, cast iron and preferably of ferrous metals comprising less than 2.0% by mass carbon as defined above. According to a particular aspect, the metallic surface considered in the present invention is not composed of non-ferrous metals, is not made of stainless steel, is not made of aluminum or titanium.

A third object of the present invention relates to a process for preparing the composition according to the first object of the invention comprising the following steps:

- the organosilane is mixed with an aqueous solution comprising a source of zirconium, optionally a surfactant, optionally an alcoholic solvent, an anticorrosion compound, an alcohol containing an acetylenic function, a quaternary ammonium salt and a polyamine, then

- the mixture is subjected to a maturation step for approximately 15 minutes minimum, at a temperature of between approximately 5 and approximately 35°C. According to one embodiment, the organosilane is dissolved in an alcoholic solvent before mixing it within the aqueous solution. According to one embodiment, the alcohol containing an acetylenic function, the quaternary ammonium salt and the polyamine are added to the aqueous solution in the form of a premix.

Preferably, in the process according to the invention, the source of zirconium, the organosilane, the anti-corrosion compound, the alcohol containing an acetylenic function, the quaternary ammonium salt, the polyamine and, where appropriate, the alcoholic solvent and the surfactant are as defined with reference to the first object of the invention.

A fourth object of the present invention relates to a kit for the preparation of a composition according to the first object of the invention comprising:

- a first compartment comprising a solution comprising an organosilane,

- a second compartment comprising an aqueous solution comprising a source of zirconium, optionally a surfactant, optionally an alcoholic solvent, an anticorrosion pigment, an alcohol containing an acetylenic function, a quaternary ammonium salt and a polyamine.

According to one embodiment, the solution comprising at least one organosilane can be an aqueous or alcoholic, preferably alcoholic, solution. Preferably, in the kit according to the invention, the source of zirconium, the organosilane, the anti-corrosion compound, the alcohol containing an acetylenic function, the quaternary ammonium salt, the polyamine and, where appropriate, the alcoholic solvent and the surfactant are as defined with reference to the first object of the invention.

The solutions present in each of the compartments have very good stability, in particular a stability of at least 6 months, preferably a stability of between 6 months and 2 years. Due to the stability of each of the solutions and their packaging in the form of a kit, the composition according to the first object can be prepared quickly, easily and subsequently to the preparation of each of said solutions for a subsequent use of the composition according to the invention. . The invention will be further illustrated by the following examples. However, these examples should in no way be interpreted as limiting the scope of the invention.

EXAMPLES

Example 1 Evaluation of the Anti-Corrosion Effect of Different Compositions on a Metal Surface Made of Carbon Steel To carry out this test, different compositions were applied to a metal surface made of carbon steel (Q-panel test panel in matt steel, model R-48), by application with a brush then left to dry at room temperature of about 20°C for about 10-20 minutes.

The appearance of corrosion on the metal surface was then assessed visually, by detecting points or orange-red areas.

The results are presented in Table 1 in which the percentages expressed are percentages by mass.

[Table 1]

6

* mixture of propargyl alcohol (based on prop-2-yn-1-ol), cocoalkyl dimethylbenzyl ammonium chloride and hexamethylenetetramine It can be seen that compositions 4, 5 and 6 which correspond to compositions according to this invention, make it possible to protect a metal surface composed of ferrous metal such as carbon steel from corrosion. In fact, after application of compositions 1, 2 or 3, the appearance of points or areas of corrosion (rust bloom) was observed whereas the corrosion could not be detected with compositions 4, 5 and 6 according to the 'invention. Thus, only the composition according to the present invention is capable of imparting an anticorrosion effect to a metal surface composed of ferrous metals after application of said composition.

This same test was carried out with composition 4 presented in Table 1 with different mixtures of propargyl alcohol.

The results are presented in Table 2 below: [Table 2]

^* mixture of propargyl alcohol, cocoalkyl dimethylbenzyl ammonium chloride and hexamethylenetetramine It can be seen that the presence of any of the mixtures based on propargyl alcohol, (conditions B, C, D) makes it possible to reduce or significantly reduce the appearance of corrosion on a metal surface made of ferrous metal such as carbon steel. In fact, after application of the composition without mixing based on propargyl alcohol, the appearance of points or areas of corrosion (rust bloom) is observed over the entire metal surface. Thus, only the compositions according to the present invention are capable of imparting an anticorrosion effect to a metal surface composed of ferrous metals after application of said composition. Example 2: Evaluation of the adhesion of a metal surface composed of mild steel to a paint

Composition 4 according to the invention was applied to a metallic surface composed of degreased mild steel and then said surface was dried at ambient temperature of approximately 20° C. for approximately 1 hour. After drying, the metal surface was painted with a primer of epoxy nature. Then, the paint was dried for 24 hours at an ambient temperature of approximately 20° C. then for 7 days in an oven at a temperature of 48° C., the film formed had a thickness of 50±10 μm. Then we measured the tearing force of a stud stuck to the surface of the paint using an automatic system of hydraulic pump and pressure sensor (Elcometer ^® 510 device), according to the ISO 4624 standard. Grid tests according to the ISO 2049 standard were also carried out. Briefly, two series of lines crossed perpendicularly are drawn on the paint using combs fitted with teeth, so as to obtain 100 squares of 1mm sides; the results are evaluated according to a rating grid ranging from 0 (edge of the cuts completely smooth, no square of the grid is detached) to 5 (a degree of peeling such that it cannot be classified in 4).

These same tests were repeated after aging of the epoxy paint under wet poultice conditions (7 days at 50°C). For comparison, the above protocol was repeated but without first applying the composition according to the invention to the metal surface. The results are shown in Table 2. [Table 3]

It can be seen that the paint adhesion remains good even after accelerated aging by wet poultice when the metal surface has been pretreated with a composition of the invention. On the other hand, in the absence of pretreatment, the adhesion of the paint drops very significantly after accelerated ageing. It should be noted that the tearing is of the adhesive type in the absence of pretreatment (the paint peels off from the support) and of the cohesive type with pretreatment (we observe breaks in the paint). Similarly, the performance in the grid test is excellent with pre-treatment of the surface, and more than mediocre in the absence of treatment. Example 3: Bonding tests on 304 and 316 stainless steel with an epoxy adhesive

The objective of this study was to investigate the performance of the treatment on the adhesion properties of different stainless steels with different roughnesses. Material and method :

Metal surfaces composed of type 304 (surface roughness Ra 0.15 and 0.46) and 316 (surface roughness Ra 0.43) stainless steel were degreased using ethanol (rinse + rubbing) then using a wipe soaked in isopropyl alcohol.

Composition 4 according to the invention was applied to the degreased metal surfaces and then said surfaces were dried at ambient temperature of approximately 20° C. for approximately lh. After drying, the metal surfaces were glued with a stud with an epoxy nature glue. Then, the glue was cured for 24 hours at an ambient temperature of approximately 20°C. Then we measured the tearing force of a pad stuck to the surface of the paint using an automatic system of hydraulic pump and pressure sensor (Elcometer ^® 510 device) according to the ISO 4624 standard. By way of comparison, the above protocol was repeated but without applying the composition according to the invention beforehand to the various metal surfaces. The results are shown in Table 3.

[Table 4]

NT = without treatment T = with treatment

The results show that the treatment clearly improves the adhesion of the adhesive by a greater tearing force and a fracture profile which does not yield to the metal/adhesive interface.

Claims

1. Chromate-free aqueous composition for forming a sol-gel type coating on a metal surface comprising: a source of zirconium, an organosilane, an anti-corrosion compound, an alcohol containing an acetylenic function, a quaternary ammonium salt , and a polyamine.

2. Composition according to claim 1, in which the source of zirconium is chosen from ammonium zirconium carbonate, hexafluorozirconic acid, zirconium acetate, zirconium carboxylate, zirconium n-propoxide, n- zirconium butoxide, zirconium oxalate, zirconium glycolate, ammonium and zirconium lactate, ammonium and zirconium citrate, zirconium nitrate or a mixture of them.

3. Composition according to claim 1 or claim 2, in which the organosilane is chosen from 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldiisopropylethoxysilane, 3-glycidoxypropyldiisopropylmethoxysilane, (3-glycidoxypropyl) methyldiethoxysilane, 2- (3,4 epoxycyclohexyl) ethyl triethoxysilane, 3-mercaptopropyltrimethoxysilane, 3- mercaptopropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3 methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, the allytriméthoxysilane, the 3-aminopropyltrimethoxysilane, 3-aminopropyl-triethoxysilane, n-phenylaminopropyltrimethoxysilane, p- or m-aminophenylsilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane or a mixture thereof.

4. Composition according to any one of the preceding claims, in which the anticorrosion compound is chosen from an acetate, borate, molybdate, nitrate, silicate or phosphate of one of the following elements: aluminum, ammonium, antimony, silver, barium, bismuth , boron, cadmium, calcium, cerium, chromium, cobalt, copper, dyprosium, gallium, indium, iron, lanthanum, lithium, magnesium, manganese, molybdenum, nickel, potassium, praseodymium, samarium, silicon, sodium, strontium, thallium, yttrium and zinc, or a mixture of the aforementioned salts.

5. Compound according to claim 4, in which the anticorrosion compound is chosen from zinc acetate, cerium nitrate or a mixture of these salts.

6. Composition according to any one of the preceding claims, in which the alcohol containing an acetylenic function is chosen from l-propyn-3-ol, l-butyn-3-ol, l-pentyn-3-ol, l-hexyn-3-ol, 1-hep tyn-3-ol, l-octyn-3-ol, l-nonyl-3-ol, 1-decyn-3-ol, l-phenyl -2-propyn-l-ol, 2-phenyl-3-butyn-2-ol, 2-methyl-l-pentyn-3-ol, 3-methyl-l-nonyn-3-ol, ethynylcyclohexanol, methylbutynol, 2-butyne-1,4-diol, 2-methyl-3-butyn-2-ol, 2,5-dimethyl-3-hexyn-2,5-diol, 2,5 -diphenyl-3-hexyne-2,5-diol, benzylbutynol, 4-ethynyl-benzyl alcohol, ethynyl-2,4,6-trimethylbenzyl alcohol, 5-decyne-4,7-diol, 4-ethyl-l-octyn-3-ol, 2-propyn-l-ol (propargyl alcohol), or mixtures thereof.

7. Composition according to any one of the preceding claims, in which the quaternary ammonium salt is a di( _CrC o)alkyldimethylammonium salt or a (CrC 3o)alkyldimethyl( _CrC 3o)alkylbenzylammonium salt.

8. A composition according to any preceding claim, which further comprises an alcoholic solvent.

9. A composition according to any preceding claim, which further comprises a surfactant.

10. Composition according to any one of the preceding claims, which comprises:

- 0.1% to 10% by weight of zirconium source;

- 0.1% to 10% by mass of organosilane;

- 0.05% to 5% by mass of anti-corrosion compound;

- 0.01% to 2% by mass of a mixture (alcohol containing an acetylenic function + quaternary ammonium salt + polyamine);

- optionally 0.1% to 10.0% by mass of alcoholic solvent;

- optionally 0.1% to 2.0% by mass of surfactant;

- the balance being 100% made up of water.

11. Use of a composition according to one of claims 1 to 10 for forming a coating of the sol-gel type on a metal surface composed of any type of metal, in which said composition is applied to the metal surface and then dried. at room temperature.

12. Use according to claim 11, in which the composition is applied to the metal surface by spraying, by roller application, by spin coating, by application of impregnated wipes, by brush application or by immersion in a bath comprising the said composition.

13. Use according to one of claims 11 or 12 wherein the metal surface is composed of at least one metal chosen from a ferrous metal, a non-ferrous metal, a ferrous and/or non-ferrous metal alloy, a precious metal .

14. Process for preparing a composition according to any one of claims 1 to 10 comprising the following steps:

- the mixture is subjected to a maturation step for a minimum of 15 minutes, at a temperature between 5 and 35°C.

15. Kit for the preparation of a composition according to one of claims 1 to 10 comprising:

- a first compartment comprising a solution comprising an organosilane,