WO2014170799A1

WO2014170799A1 - Crosslinkable varnish and method for applying same

Info

Publication number: WO2014170799A1
Application number: PCT/IB2014/060557
Authority: WO
Inventors: Olivier Renard; Stéphanie LEPKI; Thibaut MARTINI
Original assignee: Commissariat A L'energie Atomique Et Aux Energies Alternatives
Priority date: 2013-04-19
Filing date: 2014-04-09
Publication date: 2014-10-23
Also published as: FR3004720A1; FR3004720B1

Abstract

The invention concerns a crosslinkable varnish formulation and a method for depositing such a crosslinkable varnish, on a surface of a substrate. The crosslinkable varnish formulation according to the invention comprises a) at least one organosilane compound comprising two reactive silyl groups, b) at least one organosilane compound comprising three reactive silyl groups, c) optionally a catalyst for the polymerisation of at least compounds a) and b), d) at least two monomers having a (meth)acrylate function of which the vitreous transition temperature Tg is between -50°C and 70°C, inclusive, e) at least one surfactant, f) water, relative to the total volume of the formulation, and g) optionally at least one silanol stabilising agent. The invention is applicable in the field of protecting objects, in particular.

Description

CROSSLINKABLE VARNISH AND METHOD OF APPLICATION

The invention relates to a crosslinkable lacquer formulation and a method for depositing such a crosslinkable lacquer on a surface of a substrate.

Protective varnishes are widely used to impart strength properties to outdoor exposure conditions of many objects.

For reasons of mechanical properties, stability to exposure to sunlight, and flexibility in the formulation, organic / inorganic hybrid coatings are particularly suitable.

Some are obtained by sol-gel type processes, based on silica, for example. The reagents used in these types of processes are of great chemical diversity. They thus make it possible to adjust the final properties of the coating by modifying the nature of the reaction groups.

It is also known to use an inkjet process to form these coatings.

In this case, the "ink" is the crosslinkable lacquer formulation.

The inkjet process, a digital printing process, is mainly used for large format digital printing. Large format digital printing is generally done by "inks" drying by UV radiation, typically wavelengths between 200 and 400 nm.

The constraints on the properties of the "ink" are very important. For a "ink" containing a pigment, dispersion of the pigment particles without agglomeration ensures that there is no clogging of the nozzle of the ink jet apparatus.

Certain physicochemical properties of "ink" are essential for a quality impression.

Indeed, according to the heads of the inkjet devices, the surface tension, the density and the viscosity of the "ink" are critical parameters of the ejection.

Depending on these parameters, the volume of the ejected drop as well as its speed and the repeatability of the printing process may vary and degrade the quality of printing. The protective varnishes used outdoors are generally based on organic (co) polymers such as polyurethane-acrylates, polyesters, polyepoxy emulsion viscosity generally greater than 100 Cp deposited by spraying.

This viscosity appears necessary to obtain sufficient protective properties after crosslinking of the varnish, because the length of the pre-polymer chains used determines the final properties of the polymer obtained after crosslinking.

The crosslinking of the varnish can be carried out in various ways: the formulation of the crosslinkable varnish can be, for example, a two-component formulation containing a chemical catalyst, or a single-component formulation whose polymerization is carried out under UV using a photosensitive polymerization initiator .

The varnishes and inks crosslinkable by insolation by one of the wavelengths of the range of UV (λ between 200 and 400 nm) and the visible range (λ between 400 and 700 nm) can be set up by means of different photochemical mechanisms.

The two main families of varnishes and UV inks are, on the one hand, inks and varnishes using a radical polymerization mechanism and, on the other hand, varnishes and inks using a cationic polymerization mechanism.

Inks and varnishes of the sol-gel type are a class of alternative protective coatings for inks and varnishes based on organic (co) polymers.

Their inorganic nature gives them an excellent chemical resistance to multiple reagents such as solvents, acids, bases, and a high hardness, of the order of 125, when measured by the Buchholz method (NF EN ISO 2815 standard). .

Nevertheless, one of the main defects of these materials is their sensitivity to cracking phenomena that may occur at the time of their crosslinking - drying or aging, this aging can be evaluated by tests in climatic chamber. This sensitivity comes from the fact that the inorganic network is very constrained. Indeed the evaporation of solvents during drying leaves pores which are the seat of these constraints. The inorganic network not having enough degrees of freedom to accommodate these constraints, these are released by the cracking of the network. This is one of the reasons why this type of coating is limited to thin thickness, less than one micrometer, because, in this case, the adhesion of the coating to the support can contain these constraints.

Mehner et al, "Journal of Sol-Gel Science and Technology" 36, 25-32, 2005 have proposed using inorganic / organic hybrid formulations to limit the occurrence of such cracks.

This solution, even if it reduces the initial properties of these coatings, makes it possible to obtain coatings that are less sensitive to cracking after drying thanks to the flexibility of the polymer network provided by the functional groups of organic nature. This improvement can also be combined with the successive realization of thin layers with a thickness of about 200 to 300 μm. This class of hybrid materials thus makes it possible to obtain materials and coatings that combine the properties of inorganic materials (good aging, chemical resistance, mechanical characteristics) with the simplicity of implementation of organic materials.

These materials are thus used in many industrial fields such as the manufacture of materials with interesting optical properties (optical index, reflection coefficient) or anti-corrosive treatment of metal sheets for aeronautics or the automobile.

Thus, patent F 2 886 309 B1 proposes a sol for the sol-gel coating of a surface comprising, on the one hand, an organometallic compound of zirconium, aluminum or titanium and, on the other hand, an organosilane compound.

The sol-gel process is based on the high reactivity of the precursors, generally of an alkoxide nature, with respect to water; there then occurs a hydrolysis reaction continuing by a condensation process of the hydrolysed monomers leading to the formation of a polymer network. When the precursor is a silicon alkoxide, these hydrolysis reactions and polyaddition condensation can be catalyzed by the addition of a base or an acid. It then becomes possible to generate the polymerization directly on the substrate to be treated using the humidity of the air.

The patent application FR 2,843,205 A1 proposes to accelerate this reaction by the use of a photosensitive initiator of cationic nature which can thus locally release the acidic species required for the catalysis of the polymerization reaction. This flexibility thus makes it possible to produce inks with a high solids content, that is to say containing a small amount of solvent and thus making it possible to deposit, after drying, more than 50%, by weight, relative to the total mass of the ink before drying, of material, necessary for obtaining thick layers, with a thickness greater than 200 nm, preferably at 500 nm, in a minimum layer deposition, while maintaining a relatively low viscosity, typically less than 20 Cp.

Thus such inks can be compatible with an inkjet type application method.

In the case of hybrid sol-gel coatings, two types of polymerization reaction take place and take place simultaneously or consecutively, and optionally followed by a heat treatment to evaporate the solvents: the formation of the organic network generated by photocatalysis (radical or cationic) or chemical initiation; and formation of the inorganic lattice generated by cationic photocatalysis or chemical initiation. However, the kinetics of hydrolysis / condensation and polyaddition are different. But the control of the formation of the different networks is essential for the quality and performance of the final material.

It thus appears that the layers deposited by the sol-gel process and formed from sol-gel, particularly those based on silicon alkoxide, photopolymerizable or otherwise, exhibit a very significant shrinkage during drying and are therefore limited to layers of a few hundred nanom beings if the coating obtained is hard.

Indeed, the adhesion with the support then limits the removal of the coating.

The use of hybrid sol-gel precursors of silicon makes it possible to overcome part of this problem. In such hybrids, the silicon atoms carry one or more non-hydrolyzable functional groups. They correspond to the general formula (R) _x Si (OR) _y with x + y = 4, R representing a grouping organic whose bond with silicon is not hydrolyzable and R ² an organic group which leads to the release of an alcohol following the hydrolysis of Si-O bonds.

The presence of the groups R ¹ makes it possible to give some degrees of freedom to the inorganic Si-O-Si network and thus to reduce the stresses that may occur there.

Moreover, the groups R ¹ may comprise functional groups capable of forming chemical bonds with a neighboring group R ¹ , thus improving the three-dimensional crosslinking of the final hybrid polymer, without adding mechanical stresses within the network.

Such a mixture of siloxane precursors of different natures may also make it possible to better control the voltages within the network, and thus to limit the appearance of cracks and thus to make it possible to obtain coatings of greater thickness, greater than 200 nm, preferably greater than 500 nm, and even greater than 1 μιη, or even greater than 5 μηι and even 10 μηι. Formulations of this type can be made, for example, by mixing precursors of the R-Si - (- O - R ') 3 type with (R ³ ) 2 - Si - (- O - R ⁴ ) ₂ precursors such as described in EP 1 238 024.

However, such formulations do not prevent the appearance of cracks within a coating of several microns thick. In addition, when the coating obtained is subjected to an aging test under UV-visible light, the cracking phenomenon only intensifies.

Thus, it appears that up to now, there is no sol-gel-based ink formulation that makes it possible to obtain a non-cracking thick coating or after crosslinking (by UV and / or thermal), or after aging under UV-visible light.

The aim of the invention is to provide a sol-gel varnish, with a viscosity typically less than 70 cp, preferably less than 20 cp, more preferably less than 15 cp, measured with a Brookfield model DVII + Pro rotational viscometer using an axis (" Spindle "in English) S-18 with a low volume SSA adapter and a rotational speed of 180 rotations per minute (rpm), at room temperature, which can lead to the formation of a homogeneous coating, crosslinkable by heat treatment and / or a UV treatment, and that does not show cracking neither after its formation nor during its use, ie for at least 24 hours in accelerated xenon aging under irradiation at 760 W / m. (Viscometer model: DVII + Pro, Spindle S- 18 with low volume SSA adapter Rotation speed: 180rpm)

By ambient temperature is meant a temperature between

17 and 40 ° C.

For this purpose, the invention provides a crosslinkable lacquer formulation comprising:

a) at least one organosilane compound comprising two reactive silyl groups,

b) at least one organosilane compound comprising three reactive silyl groups,

c) optionally a polymerization catalyst of at least compounds a) and b),

d) at least two monomers having an acrylate or methacrylate function,

e) at least one surfactant,

f) water, and

g) optionally at least one silanol stabilizing agent, characterized in that the monomers having a function

(meth) acrylate or methacrylate d) are selected from lauryl acrylate, tetra (ethylene glycol) diacrylate, tnmethylol propane triacrylate, and mixtures thereof.

In the formulation of the invention, the surfactant is selected from a silicone acrylate and glycerol and mixtures thereof, preferably is a silicone acrylate.

Preferably, the monomers d) are identical and are chosen from monomers tetra (ethylene glycol) diacrylate and trimethylol propane triacrylate.

As for the silanols stabilizing agent g), it is chosen from organic or inorganic carboxylic acids having a pka of between 2 and 5. included, preferably selected from acetic acid, valeric acid, stearic acid and methacrylic acid, most preferably methacrylic acid.

The organosilane compound comprising two reactive silyl groups a) has the generic formula Z ^! Z ² SiZ ³ Z ⁴ in which:

Z and Z are identical or different and represent non-reactive silyl groups, and

Z ³ and Z ⁴ are identical or different and represent reactive silyl groups.

Z ¹ and Z ² are chosen from R ² groups. Z ³ and Z ⁴ are chosen from a halogen, in particular chlorine, and a group OR ³ , R ² and R ^J preferably representing linear or branched, optionally substituted, possibly cyclic, C-C 50 alkyls, optionally containing unsaturations of the double type, or triple bond or aromatic group.

By reactive silyl group means a group whose covalent bond with silicon is hydrolyzable in contrast to a non-reactive silyl group.

More particularly, the organosilane compound comprising two reactive silyl groups a) is chosen from alkoxy and / or hydroxy-terminated polydimethylsiloxanes having a molecular weight of 400 to 150,000; alkoxy and / or hydroxy terminated diphenylsiloxane dimethylsiloxane copolymers; alkoxy and / or hydroxy terminated polydiphenylsiloxanes; hydroxysilyl and / or alkoxysilyl terminated poly (thiotrifluoropropylmethylsiloxanes, polyesters, polyurethanes, and polyacrylates; dialkyl-substituted dialkyl- and dialkoxy-silanes, such as diethyldiethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane, diisobutyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, bis (3-cyanopropyl) dimethoxysilane, (2-chloroethyl) methyldimethoxysilane, the chlorométhylméthyldiéthoxysilane, (2-chloroethyl) méthyldiisopropoxysilane, the (3-chloropropyl) methyldimethoxysilane, (3-cyanopropyl) méthyldiméthoxysiîane the cyclohexyléthyldiméthoxysilane the dodécylméthyldiéthoxysilane, isobutylmethyldimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, diethylsilane mercaptométhylméthyl the méthacryioxypropylméthylidiéthoxysiiane, the methacryloxypropylmethyldimetoxysilane, methyldiethoxysilane, methyldimethoxysilane, n-octadecylmethyldiethoxysilane; n-octylmethyldiethoxysilane, dicyclopentyldimethoxysilane; substituted aryl and diaryl alkoxysilanes, such as diphenyldimethoxysilane, phenyldiethoxysilane, phenylmethyldiethoxysilane, phenylmethane dimethoxysilane; substituted hydroxysilyl and alkoxysilyl arenes such as 1,4-bis (hydroxydimethylsilyl) benzene, 1,3-bis (methoxydimethylsilyl) benzene; substituted trialkylsilyl alkoxysilanes, such as bis (trimethylsilylmethyl) dimethoxysilane, trimethylsilylmethyl-dimethoxysilane; cyclic alkoxysilanes, such as 1,1-diethoxy-1-silacyclopent-3-ene; substituted acyloxy silanes such as dimethyldiacetoxysilane, vinylmethyldiacetoxysilane, diethylbenzoyloxyacetoxysilane; geminal silanediols, such as diphenylsilanediol, dicyclohexylsilanediol; substituted alkyl and / or aryl substituted cyclic siloxanes, such as 3- (3,3,3-trifluoropropyl) heptamethyltrisiloxane, hexamethyltrisiloxane, octamethyltetrasiloxane; Substitutes alkenyl alkoxysilanes, such as vinylmethyldiethoxysilane, vinylmethyldimethoxysilane, the vinylphényldiéthoxysilane, 3-glycidoxypropyldiméthoxyméthylsiîane, dimethyldichlorosilane, dichlorotetraméthyldisiloxane the dichlorohexaméthyltrisiloxane, bis (trimethylsiloxy) dichlorosilane, the éthylniéthyldichlorosilane the propylmethyldichlorosilane, the hexaméthyldichlorosilane, the heptylniéthyldichlorosilane the octylmethyldichlorosilane, the décylméthyldichlorosilane the dodecylmethyldichlorosilane the octadécylméthyldichlorosilane, isopropylméthyldichlorosilane, t-butylméthyldichlorosilane the cyclohexylméthyldichlorosilane, phenylmethyldichlorosilane, the phènéthylméthyldichlorosilane, (3-phenylpropyl) methyldichlorosilane, 4- phénylbutyîméthyldichlorosilane the phénoxypropylméthyldichlorosiîane, 3 (p-methoxyphenyl) propylmethyldichlorosilane, diethyldichlorosilane, diisopropyldichlorosilane, i-n-butyldichlorosilane, dicyclopentyldichiorosilane, di-n-hexyldichlorosilane and di-n-octyldichlorosilane, and mixtures thereof, preferably is vinylmethyldiethoxysilane. The organosilane compound comprising three reactive silyl groups b) has the formula Z'SiZ ³ Z ⁴ Z ⁵ in which Z ¹ is a non-reactive silyl group and Z ³ , Z ⁴ and Z ⁵ , which are identical or different, are silyl groups reagents. Z ¹ is chosen from R ⁴ groups. Z ³ , Z ⁴ and Z ⁵ are chosen from a halogen, in particular chlorine, and a group OR ⁵ , R ⁴ and R ⁵ preferably representing linear or branched, optionally substituted, optionally cyclic C1-C50 alkyls, optionally having unsaturations of the double type, or triple bond or aromatic group.

More particularly, the organosilane compound comprising three reactive silyl groups b) is chosen from isobutyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, octyltriethoxysilane, propyltrimethoxysilane, phenyltrimethoxysilane, chloropropyltriethoxysilane, chloroproyltrimethoxysilane, mercaptopropyltrimethoxysilane, glycidyloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and mixtures thereof, preferably is glycidyloxypropyltrimethoxysilane.

The polymerization catalyst c) is chosen from triphenylsulfonium tetrafluoroborate; triphenylsulfonium tetrakis (pentafluorobenzyl) borate; methyldiphenylsulfonium tetrafluoroborate; methyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; dimethylphenylsulfonium hexafluorophosphate; triphenylsulfonium hexafluorophosphate; triphenylsulfonium hexafluoroantimonate; diphenylnaphthylsulfonium hexafluoroarsenate; tritolysulfonium hexafluorophosphate; anisyldiphenylsulfonium hexafluorantimonate; 4-butoxyphenyldiphenylsulfonium tetrafluoroborate; 4-butoxyphenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; 4-chlorophenyldiphenylsulfonium hexafluoroantimonate; tris (4-phenoxyphenyl) sulfonium hexafluorophosphate; di (4-ethoxyphenyl) methylsulfonium hexafluoroarsenate; 4-acetylphenyldiphenylsulfonium tetrafluoroborate; 4-acetylphenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; the fris (4-thiomethoxyphenyl) sulfonium hexailuorophosphate; di (methoxysulfonylphenyl) methylsulfonium hexafluoroantimonate; di (methoxynaphthyl) methylsulfonium tetrafluoroborate; di (methoxynaphthyl) methylsulfonium tetrakis (pentafluorobenzyl) borate; di (carbomethoxyphenyl) methylsulfonium hexailuorophosphate; (4-octyloxyphenyl) diphenylsulfonium tetrakis (3,5-bis-trifluoromethylphenyl) borate; tris (dodecylphenyl) sulfonium tetrakis (3,5-bis-trifluoromethylphenyl) borate; 4-acetamidophenyldiphenylsulfoniran tetrafluoroborate; 4-acetamidophenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; dimethylnaphthylsulfonium hexailuorophosphate; trifluoromethyldiphenylsulfonium tetrafluoroborate; trifluoromethyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; phenylmethylbenzylsulfonium hexailuorophosphate; 10-methylphenoxathiinium hexailuorophosphate; 5-methylthianthrenium hexailuorophosphate; 10-phenyl-9,9-dimethylthioxanthenium hexailuorophosphate; 10-phenyl-9-oxothioxanthenium tetrafluoroborate; 10-phenyl-9-oxothioxanthenium tetrakis (pentafluorobenzyl) borate; 5-methyl-10-oxothianthrenium tetrafluoroborate; 5-methyl-10-oxothiantenium tetrakis (pentafluorobenzyl) borate; (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexailuorophosphate; 5-methyl-10,10-dioxothianthrenium hexailuorophosphate, di (dodecylphenyl) iodonium hexafluoroantimonate, di (dodecylphenyl) iodonium trifiate; diphenyliodonium bisulfate, 4,4'-dichlorodiphenyliodonium bisulfate; 4,4'-dibromodiphenyliodonium bisulfate; 3,3'-dinitrodiphenyliodonium bisulfate; 4,4'-dimethyldiphenyliodonium bisulfate; ^4,4, -bissuccinimidodiphényliodonium bisulfate; 3-nitrodiphenyliodonium bisulfate; 4,4'-dimethoxydiphenyliodonium bisulfate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate; (4-octyloxyphenyl) phenyliodonium tetrakis (3,5-bis-trifluoromethylphenyl) borate: (tolylcumyl) iodonium tetrakis (pentafluorophenyl) borate (CH ₃ C ₆ H ₄ ) ₂ I- (SO ₂ CF ₃ ) _3> methyltrichlorosilane, trimethylsiloxytrichlorosilane, ethyltrichlorosilane, propyltrichlorosilane, n-butyltrichlorosilane, pentyltrichlorosilane, hexyltrichlorosilane, heptylirichlorosilane, octyltrichlorosilane, decyltrichlorosilane, undecylirichlorosilane, dodecyltrichlorosilane, tetradecyltrichlorosilane, hexadecyltrichlorosilane, octadecyltrichlorosilane, Feicosyltrichlorosilane, isobutyltrichlorosilane the cyclopentyltrichlorosilane, the (3,3-dimethylbutyl) trichlorosilane, bicycloheptyltrichlorosilane, isooctyltrichlorosilane, adamantyléthyltrichlorosilane, (di-n-octylméthylsilyl) ethyltrichlorosilane, phenyltrichlorosilane, benzyltrichlorosilane the the phènéthyltrichlorosilane, 4- phénylbutyltrichlorosilane the phénoxypropyltrichlorosilane phenoxyundecyltrichlorosilane, (1-naphthylmethyl) trichlorosilane, preferably is (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate.

The preferred proportions of each of the components a) to g), in% by weight, relative to the total weight of the formulation are the following:

between 10% and 90%, preferably between 30% and 80% of organosilane compound comprising two reactive silyl groups a),

between 10% and 90%, preferably between 30 and 80% of organosilane compound comprising three reactive silyl groups b),

between 0 and 10%, preferably between 0 and 7%, and more preferably between 0 and 5%, of polymerization catalyst c),

between 0.1% and 30%, preferably between 0.1% and 20%, more preferably between 0.1% and 10% of monomers having a (meth) acrylate function,

between 0.1% and 10%, preferably between 0.1% and 5%, more preferably between 0.1% and 3% of at least one surfactant e),

between 15% inclusive and 35% excluded, preferably between 15 and 25% inclusive, of water f), and

between 0 and 30%, preferably between 0 and 10%, more preferably between 0 and 5% of silanols stabilizing agent g).

The formulation according to the invention may further comprise an organosilane compound comprising from 4 to 6 reactive silyl groups and / or an organosilane compound comprising a single reactive silyl group.

The invention also proposes a method of depositing a layer of varnish on the surface of a substrate, characterized in that it comprises the following steps:

A) mixture of at least one organosilane compound comprising two reactive silyl groups a), at least one organosilane compound comprising three reactive groups b), optionally at least one polymerization catalyst of compounds a), b) and c), water (f)), at least one surfactant e), at least two monomers having a function acrylate d), and optionally at least one silanols stabilizing agent g), for at least 1 hour, preferably for 24 to 48 hours at room temperature,

B) depositing, preferably by ink jet, the mixture obtained in step A) on the surface of a substrate,

C) crosslinking of the mixture deposited in step B) by exposure to the stress at which the catalyst c) is sensitive,

characterized in that the at least two monomers having (meth) acrylate function d) are preferably selected from lauryl acrylate, tetra (ethylene glycol) diacrylate, trimethylol propane triacrylate, and mixtures thereof. Preferably, the monomers are identical and are chosen from tetra (ethylene glycol) diacrylate and trimethylol propane triacrylate.

In the process of the invention, the surfactant e) is selected from silicone acrylate, glycerol and mixtures thereof. Preferably it is a silicone acrylate.

The stabilizing agent silanols, it is selected from acetic acid, valeric acid, stearic acid and methacrylic acid, most preferably is methacrylic acid. Preferably, it is methacrylic acid.

The organosilane compound comprising two reactive silyl groups a) has the generic formula Z ¹ Z ² SiZ Z ⁴ in which:

Z ¹ and Z ² are identical or different and represent non-reactive silyl groups, and

Z ³ and Z ⁴ are identical or different and represent reactive silyl groups.

Z ¹ and Z ² are chosen from R ² groups. Z ³ and Z ⁴ are chosen from a halogen, in particular chlorine, and a group OR ³ , R ² and R ³ preferably representing linear or branched, optionally substituted, optionally cyclic CC ₅ 0 alkyls, optionally having unsaturations of the double type, or triple bond or aromatic group. More particularly, the organosilane compound comprising two reactive silyl groups a) is selected from alkoxy and / or hydroxy terminated polydimethylsiloxanes having a molecular weight of 400 to 150,000; alkoxy- and / or hydroxy-terminated diphenylsiloxane-dimethylsiloxane copolymers; alkoxy and / or hydroxy terminated polydiphenylsiloxanes; hydroxysilyl and / or alkoxysilyl terminated polytrifluoropropylmethylsiloxanes, polyesters, polyurethanes, and polyacrylates; dialkyl-substituted dialkyl- and dialkoxy-silanes, such as diethyldiethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane, diisobutyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, bis (3-cyanopropyl) dimethoxysilane, (2-chloroethyl) methyldimethoxysilane, the chlorométhylméthyldiéthoxysilane, (2-chloroethyl) méthyldiisopropoxysilane, the (3-chloropropyl) methyldimethoxysilane, (3-cyanopropyl) methyldimethoxysilane, cyclohexyléthyldiméthoxysilane the dodécylméthyldiéthoxysilane, isobutylmethyldimethoxysilane, 3-mercaptopropylméthyîdiméthoxysilane, diethylsilane mercaptométhylméthyl the méthacryloxypropylméthylidiéthoxysilane, methacryloxypropylmethyldimethoxysilane, methyldiethoxysilane, methyldimethoxysilane, n-octadecylmethyldiethoxysilane; n-octylmethyldiethoxysilane, dicyclopentyldimethoxysilane; aryl and diaryl substituted alkoxysilanes, such as diphenyldimethoxysilane, phenyldiethoxysilane, phenylmethyldiethoxysilane, phenylmethyldimethoxysilane; substituted hydroxysilyl and alkoxysilyl arenes such as 1,4-bis (hydroxydimethylsilyl) benzene, 1,3-bis (methoxydimethylsilyl) benzene; trialkylsilyl substituted alkoxysilanes, such as bis (trimethylsilylmethyl) dimethoxysilane, trimethylsilylmethyl-dimethoxysilane; cyclic alkoxysilanes, such as 1,1-diethoxy-3-silacyclopent-3-ene; substituted acyloxy silanes such as dimethyldiacetoxysilane, vinylmethyldiacetoxysilane, diethylbenzoyloxyacetoxysilane; geminal silanediols, such as diphenylsilanediol, dicyclohexylsilanediol; substituted alkyl and / or aryl substituted cyclic siloxanes, such as 3- (3,3,3-trifluoropropyl) heptamethyltrisiloxane, hexamethyltrisiloxane, octamethylketrasiloxane; the substituted alkoxysilanes alkenyl, such as vinylmethyldiethoxysilane, the vinylmé yldiméthoxysilane the vinylphényldiéthoxysilane, 3-glycidoxypropyldiméthoxyméthylsilane the diméthyldichîorosilane the dichîorotetramét yldisiloxane the dichlorohexaméthyltrisiloxane, bis (trimethylsiloxy) dichlorosilane, éthylméthyldichlorosilane the propylmethyldichlorosilane, the hexaméthyldichlorosilane the heptylniéthyldichlorosilane, the 'octylmethyldichlorosilane, the décylméthyldichlorosilane the dodecylmethyldichlorosilane, roctadécylméthyldichlorosilane the isopropylniéthyldic lorosilane, t-butylméthyldichlorosilane the cyclohexylméthyldichlorosilane, phenylmethyldichlorosilane, the phènéthylméthyldichlorosilane, (3-phényIpropyl) methyldichlorosilane, 4- phénylbutylméthyldichlorosilane the phénoxvpropylméthyldichlorosilane, 3- ( p-methoxyphenyl) propylmethyldichlorosilane, diethyldichlorosilane, diisopropyldichlorosilane, di-n-butyldichlorosilane, dicyclo pentyldichlorosilane, di-n-hexyldichlorosilane and di-n-octyldichlorosilane, and mixtures thereof. Vinylmethyldiethoxysilane is preferably used.

The organosilane compound comprising three reactive silyl groups b) has the formula Z'SiZ ³ Z ⁴ Z ⁵ in which Z ¹ is a non-reactive silyl group and Z ³ , Z ⁴ and Z ⁵ , which are identical or different, are silyl groups reagents. Z ¹ is chosen from R ⁴ groups. Z ³ , Z ⁴ and Z ⁵ are chosen from a halogen, in particular chlorine, and a group OR ³ , R ⁴ and R ⁵ preferably representing linear or branched, optionally substituted, optionally cyclic Ci-C ₅₀ alkyls. , optionally having unsaturations of the double type, or triple bond or aromatic group.

The organosilane compound having three reactive silyl groups b) is selected from risobutyltriméthoxysilane, methyltriethoxysilane, methyltrimethoxysilane, octyltriethoxysilane, propyltrimethoxysilane, phenyltrimethoxysilane, chloropropyltriethoxysilane, chloroproyltriméthoxysilane, mercaptopropyltrimethoxysilane, glycidyloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, dimethyldichlorosilane, dichlorotetraméthyldisiloxane the dichlorohexaméthyltrisiloxane, bis (trimethylsiloxy) dichlorosilane, Γ éthylméthyldichlorosilane the propylmethyldichlorosilane, the hexaméthyldichlorosilane, heptylméthyldichlorosilane the octylmethyldichlorosilane, the décylméthyldichlorosilane the dodecylmethyldichlorosilane, roctadécylméthyldichlorosîlane, Tisopropyln ethyldichlorosilane, t butylméthyldichlorosilane the cyclohexylméthyldichlorosilane, phenylmethyldichlorosilane, phenethylmethyldichlorosilane, (3-phenylpropyl) methyldichlorosilane, 4-phenylbutylmethyldichlorosilane, phenoxypropylmethyldichlorosilane, 3- (p-methoxyphenyl) propylmethyldichlorosilane, diethyldichlorosilane, diisopropyldichlorosilane, di-n-butyldichlorosilane, dicyclopentyldichlorosilane, di-n- hexyldichlorosilane and di-n-octyldichlorosilane, methyltrichlorosilane, trimethylsiloxytrichlorosilane, ethyltrichlorosilane, propyltrichlorosil ane, n-butyltrichlorosilane, pentyltrichlorosilane, hexyltrichlorosilane, heptyltrichlorosilane, octylirichlorosilane, decyltrichlorosilane, undecyltrichlorosilane, dodecyltrichlorosilane, tetradecyltrichlorosilane, hexadecyltrichlorosilane, octadecyltrichlorosilane, eicosyltrichlorosilane, sobutyltrichlorosilane, cyclopentyltrichlorosilane, (3,3-dimethylbutyl) trichlorosilane, bicycloheptylchiorosilane, risooctytrichlorosilane, adamantylethyltrichlorosilane, (di-n-octylmethylsilyl) ethyltrichlorosilane, phenyltrichlorosilane, benzyltrichlorosilane, phenethyltrichlorosilane, 4-phenylbutyltrichlorosilane, phenoxypropyltrichlorosilane, phenoxyundecyltrichlorosilane, naphthylmethyl) trichlorosilane, and mixtures thereof. Preferably, glycidyloxypropyltrimethoxysilane is used.

The polymerization catalyst c) is chosen from triphenylsulfonyltetrafluoroborate; triphenylsulfonium tetrakis (pentafluorobenzyl) borate; methyldiphenylsulfonium tetrafluoroborate; methyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; dimethylphenylsulfonium hexafluorophosphate; triphenylsulfonium hexafluorophosphate; triphenylsulfonium hexafluoroantimonate; diphenylnaphthylsulfonium hexafluoroarsenate; tritolysulfonium hexafluorophosphate; anisyldiphenylsulfonium hexafluorantimonate; 4-butoxyphenyldiphenylsulfonium tetrafluoroborate; the

butoxyphenyldiphenyl sulphonium tetrakis (pentafluorobenzyl) borate;

chlorophenyldiphenyl sulphonium hexafluoroantimonate; the

phenoxyphenyl) sulfonium hexafluorophosphate; the

ethoxyphenyl) methyl sulphonium hexafluoroarsenate; the

acetylphenyldiphenyl sulphonium tetrafluoroborate; 4-acetylphenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; tris (4-thiomethoxyphenyl) sulfonium hexafluorophosphate; di (methoxysulfonylphenyl) methylsulfonium hexafluoroantimonate; di (methoxynaphthyl) methylsulfonium tetrafluoroborate; di (methoxynaphthyl) methylsulfonium tetrakis (pentafluorobenzyl) borate; Di (carbomethoxyphenyl) methylsulfonium hexafluorophosphate; (4-octyloxyphenyl) diphenylsulfonium tetrakis (3,5-bis-trifluoromethylphenyl) borate; tris (dodecylphenyl) sulfonium tetrakis (3,5-bis-trifluoromethylphenyl) borate; 4-acetamidophenyldiphenylsulfonium tetrafluoroborate; 4-acetamidophenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; dimethylnaphthylsulfonium hexafluorophosphate; trifluoromethyldiphenylsulfonium tetrafluoroborate; trifluoromethyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; phenylmethylbenzylsulfonium hexafluorophosphate; 10-methylphenoxathiinium hexafluorophosphate; 5-methylthianthrenium hexafluorophosphate; 10-phenyl-9,9-dimethylthioxanthenium hexafluorophosphate; 10-phenyl-9-oxothioxanthenium tetrafluoroborate; 10-phenyl-9-oxothioxanthenium tetrakis (pentafluorobenzyl) borate; 5-methyl-10-oxothianthrenium tetrafluoroborate; 5-methyl-10-oxothiantenium tetrakis (pentafluorobenzyl) borate; (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate; 5-methyl-10,10-dioxothianthrenium hexafluorophosphate, di (dodecylphenyl) iodonium hexafluoroantimonate, di (dodecylphenyl) iodonium triflate; diphenyliodonium bisulfate, 4,4'-dichlorodiphenyliodonium bisulfate; ^4,4, -dibromodiphényliodonium bisulfate; 3,3'-dinitrodiphenyliodonium bisulfate; 4,4'-dimethyldiphenyliodonium bisulfate; 4,4'-bisuccimmidodiphenyliodonium bisulfate; 3-nitrodiphenyliodonium bisulfate; 4,4'-dimethoxydiphenyliodonium bisulfate, bis (dodecylphenyl) iodonium tetrakis (pentafruorophenyl) borate; (4-octyloxyphenyl) phenyliodonium tetrakis (3,5-bis-trifluoromethylphenyl) borate: (tolylcumyl) iodonium tetrakis (pentafluorophenyl) borate (CH ₃ C ₆ H ₄ ) 21- (SO ₂ CF ₃ ) 3, Preferably, (4-metbylpienyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate.

In one embodiment of the process of the invention, the mixture of stage A comprises, in% by weight relative to the total mass of said mixture:

between 0.1% and 30%, preferably between 0.1% and 20%, more preferably between 0.1% and 10%, of monomers having a (meth) acrylate function,

between 15% inclusive and 35% excluded, preferably between 15% and 25% inclusive of water f), and

between 0 and 30%, preferably 0 and 10%, more preferably between 0 and 5% silanol stabilizing agent g).

In addition, the mixture of step A may also comprise at least one organosilane compound comprising from 4 to 6 reactive silyl groups and / or at least one organosilane compound comprising a reactive silyl group.

The invention will be better understood and other advantages and characteristics thereof will appear more clearly on reading the explanatory description which follows.

The appearance of cracks in a coating obtained from a curable varnish, being formed, is related to two phenomena appearing together: the shrinkage and the evaporation of the solvent (s). Sol-gel coatings are particularly sensitive to these two phenomena, due to the inflexible nature of the inorganic network that is formed.

Furthermore, another cause of cracking such coatings is the nature of the polymer (s) constituting them, including its (their) temperature (s) glass transition.

The lower the vitreous transition temperature of the polymer formed, the better the stretch of the varnish obtained, but if the glass transition temperature is too low, the polymer will be too soft.

The greater the flexibility within the formed inorganic network, the lower the risk of cracking.

This flexibility is conferred, in the case where the varnish is formed by polymerization of silicon alkoxide monomers, by the nature of silicon-bonded alkoxy groups.

In order to carry out the polymerization of the inorganic network with a sol-gel coating, it is necessary to carry out the hydrolysis of the alkoxide groups and then to cause their condensation.

In the case of silicon alkoxides, the kinetics of these reactions is slow: it is generally necessary to catalyze them.

In the case of coatings, the catalysis is carried out in acidic medium so as not to densify the inorganic network too much, otherwise particle formation will occur.

In order to minimize the problems of capillarity related to the evaporation of the solvents and therefore the risks of cracking of the coating, it is preferable to formulate inks with a high solids content, that is to say at least 50%, even greater than 70%.

The alkoxides can be hydrolysed by the humidity of the air: the use of acid-generating photoinitiators can trigger the hydrolysis-condensation of the inorganic part directly on the substrate where the ink is deposited by the UV exponents. .

The crosslinkable lacquer formulation of the invention therefore comprises: a) at least one organosilane compound comprising two reactive silyl groups of formula (R) ₂ Si (OR); in which R represents a grouping whose bond with Si is not hydrolyzable and R ³ represents a group whose bond with silicon is hydrolysable, due to the presence of oxygen. This compound makes it possible to reduce the viscosity of the crosslinkable lacquer formulation and thus increases the ejectability of the varnish.

b) at least one organosilane compound comprising three reactive silyl groups, of formula R ⁴ Si (OR ⁵ ) ₃ in which R ⁴ represents a group whose bond with Si is not hydrolysable and R ⁵ represents a group whose bond with the silicon is hydrolysable, because of the presence of oxygen. This compound makes it possible to increase the chemical and mechanical resistance of the coating but thereby increases the stresses generated during the drying of the varnish,

The formulation of the invention may furthermore comprise c) a catalyst for catalyzing the polymerization reaction of the organosilane compounds.

The crosslinkable lacquer formulation of the invention further comprises f) water. Indeed, it has been unexpectedly found that in order to limit the occurrence of cracking-crosslinking, including over time, it is necessary to pre-hydrolyze the alkoxides, if they are not already, and the stabilize in the form of silanols, then condense them once the varnish is deposited. The addition of water also makes it possible to reduce the viscosity of the crosslinkable lacquer formulation of the invention and thus allow its application by inkjet.

It may be necessary to stabilize the silanols formed in order to avoid their condensation before the application of the varnish, otherwise the viscosity of the varnish will be increased and thus its possibilities of application will be reduced.

In this case, generally, the silanols products are stabilized by carrying out the hydrolysis in an acid medium, that is to say at a pH of between 1 and 4. For example, when using the acid The pH of the hydrolysis can vary depending on the nature of the silicon alkoxides.

The acids that can be used are organic and inorganic carboxylic acids having a pka of between 2 and 5 inclusive. Acetic acid, valeric acid and methacrylic acid may be mentioned.

But, in the context of the formulation of the invention, when their use is necessary, it is preferable to use silanol stabilizers which will be integrated, during the polymerization, in the structure of the final coating. Indeed, the varnish formulation of the invention further comprises d) at least two monomers having a function (méfh) acrylate to improve the tension and gloss of the final varnish. These monomers must form a polymer having a Tg between -50 ° C and 70 ° C. Indeed, if the Tg (glass transition temperature) of the polymer is too low, the varnish will have a hardness too low corresponding to incomplete polymerization. If the Tg is too high, the varnish formed will be too friable and cracking will occur.

Due to the use of such monomers having (meth) acrylate functions, it will therefore preferably be used as stabilizer silanols g) methacrylic acid.

The crosslinkable lacquer formulation of the invention further comprises at least one surfactant e) incorporated in the network to reduce and homogenize the pores related to the evaporation of the solvent. It will also provide the proper surface tension for ejection of the ink jet ink.

According to a variant of the invention, the formulation may, in addition, comprise inorganic particles conferring mechanical or UV-resistant properties such as micro- or nanometric fabric particles of Si (½, TiO 2, ZnO or mixtures thereof.

The organosilane compound comprising two reactive silyl groups a) is preferably selected from alkoxy- and / or hydroxy-terminated polydimethylsiloxanes having a molecular weight of 400 to 150,000; alkoxy and / or hydroxy terminated diphenylsiloxane dimethylsiloxane copolymers; alkoxy and / or hydroxy terminated polydiphenylsiloxanes; hydroxysilyl and / or alkoxysilyl terminated polytrifluoropropylmethylsiloxanes, polyesters, polyurethanes, and polyacrylates; dialkyl-substituted dialkyl and dialkyl silanes, such as difhyldiethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane, diisobutyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, bis (3-cyanopropyl) dimethoxysilane, (2-chloroethyl) methyldimethoxysilane, chloromethylmethyldiethoxysilane, (2-chloroethyl) methyldiisopropoxysilane, (3-chloropropyl) methyldimethoxysilane, (3-cyanopropyl) methyldimethoxysilane, cyclohexylethyldimethoxysilane, dodecylmethyldiethoxysilane, risobutylmethyldimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, mercaptomethylmethyl diethylsilane, methacryloxypropylmethylidiethoxysilane, methacryloxypropylmethyldimethoxysilane, methyldiethoxysilane, methyldimethoxysilane, n-octadecylmethyldiethoxysilane; n-octylmethyldiethoxysilane, dicyclopentyldimethoxysilane; substituted aryl and diaryl alkoxysilanes, such as diphenyldimethoxysilane, phenyldiethoxysilane, phenylmethyldiethoxysilane, phenylmethyldimethoxysilane; substituted hydroxysilyl and alkoxysilyl arenes such as 1,4-bis (hydroxydimethylsilyl) benzene, 1,3-bis (methoxydimethylsilyl) benzene; alkoxysilanes Substitutes trialkylsilyl, such as bis (trimethylsilylmethyl) dimethoxysilane ₅ the triméthylsilylméthyl- dimethoxysilane; cyclic alkoxysilanes such as 1,1-diethoxy-1-silacyclopent-3-ene; substituted acyloxy silanes such as dimethyldiacetoxysilane, vinylmethyldiacetoxysilane, diethylbenzoyloxyacetoxysilane; geminals, such as diphenylsilanediol, dicyclohexylsilanediol; substituted alkyl and / or aryl substituted cyclic siloxanes, such as 3- (3,3,3-trifluoropropyl) heptamethyltrisiloxane, hexamethyltrisiloxane, octamethyltetrasiloxane; Substitutes alkenyl alkoxysilanes, such as vinylmethyldiethoxysilane, vinylmethyldimethoxysilane, the vinylphényldiéthoxysilane, 3-glycidoxypropyldiméthoxyméthylsilane, dimethyldichlorosilane, dichlorotetraméthyldisiloxane the dichlorohexaméthyltrisiîoxane, bis (trimethylsiloxy) dichlorosilane, the éthylméthyldichlorosilane the propylmethyldichlorosilane, rhexaméthyîdichlorosilane the heptylméthyldichlorosilane, roctylmethyldichlorosilane, decylmethyldichlorosilane, dodecylmethyldichlorosilane, octadecylmethyldichlorosilane, isopropylmethyldichlorosilane, t-butylmethyldichlorosilane, cyclohexylmethyldichlorosilane, phenylmethyldichlorosilane, phenethylmethyldichlorosilane, (3-phenylpropyl) methyldichlorosilane _; 4-phenylbutylmethyldichlorosilane, phenoxypropylmethyldichlorosilane, 3- (p-methoxyphenyl) propylmethyldichlorosilane, diethyldichlorosilane, diisopropyldichlorosilane, di-n-butyldichlorosilane, dicyclopentyldichlorosilane, di-n-hexyldichlorosilane and di-n-octyldichlorosilane, and mixtures thereof. Of these, vinylmethyldiethoxysilane is preferred.

As the organosilane compound having three reactive silyl groups b), it may be selected from risobutyltriméthoxysilane, methyltriethoxysilane, methyltrimethoxysilane, octyltriethoxysilane, the propyltriméfhoxysilane, phenyltrimethoxysilane, chloropropyltriethoxysilane, chloroproyltriméthoxysilane, mercaptopropyltrimethoxysilane, glycidyloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, the vinyltriétïioxysilane the vinyltriméthoxysiîane, 3- glycidoxypropyldiméthoxyméthylsilane, dimethyldichlorosilane, dichlorotetraméthyldisiloxane the dichloroliexaméthyltrisiloxane, bis (trimethylsiloxy) dichlorosilane, the éthylméthyldichlorosilane the propylmethyldichlorosilane, the hexaméthyldichlorosilane the heptylméthyldichlorosilane, i'octylméthyldichlorosilane the décylméthyldichlorosÎlane, the dodecylmethyldichlorosilane, octadecylmethyldichlorosilane, isopropylmethyldichlorosilane, t-butylmethyl dichlorosilane, cyclohexylmethyldichlorosilane, phenylmethyldichlorosilane, phenethylmethyldichlorosilane, (3-phenylpropyl) methyldichlorosilane, 4-phenylbutylmethyldichlorosilane, phenoxypropylmethyldichlorosilane, 3- (p-methoxyphenyl) propylmethyldichlorosilane, diethyldichlorosilane, diisopropyldichlorosilane, di-n-butyldichlorosilane. , dicyclopentyldichlorosilane, di-n-hexyldichlorosilane and di-n-octyldichlorosilane, and mixtures thereof. Of these, glycidyloxypropyltrimethoxysilane is preferred.

Monomers having (meth) acrylate functions d) are monomers comprising at least one acrylate or methacrylate function. They will also be noted in the present text "monomers comprising at least one acrylate function".

Examples of such monomers include 1,3-butylene glycol dimethacrylate (BDMA), 1,6-hexanediol diacrylate (Tg 43 ° C), 1,6-hexanediol dimethacrylate (HXMA), 1 , 9-nonaediol diacrylate, 2- [3- (2H-Benzotriazol-2-yl) -4-hydroxyphenyl] ethyl methacrylate, 2-ethoxyethyl acrylate (Tg -50 ° C), 2-ethylbutyl acrylate (Tg -50 ° C), 2-ethylbutyl methacrylate (Tg 11 ° C),

2-ethylhexyl acrylate (Tg -50 ° C), 2-ethylhexyl methacrylate (EHMA) (Tg -10 ° C), 2-heptyl acrylate (Tg -38 ° C), 2-hydroxyethyl methacrylate (EHMA) ( Tg 55 ° C), 2-hydroxypropyl methacrylate (HPMA) (Tg 26 ° C), 2-methacryloyloxyethyl phthalic acid (PA) (Tg 75 ° C), 2-methacryloyloxyethyl succinic acid (SA) (Tg 20 °) C), 2-methoxyethyl acrylate (2-MTA) (Tg -50 ° C), 2-phenoxy acrylate (Tg -22 ° C),

3- (Trimethoxysilyl) propyl methacrylate, 3-ethyl-3-oxetanylmethyl acrylate, 4-hydroxybutyl acrylate (4HBA) (Tg -32 ° C), allyl methacrylate (AMA) (Tg 52 ° C), diethylaminoethyl methacrylate (DEMA) (Tg 20 ° C), dimethylaminoethyl methacrylate (DMMA) (Tg 18 ° C), dioloxane acrylate (Tg -7 ° C), ethoxyethoxyethyl acrylate (# 190) (Tg -67 ° C) , ethoxyethyl methacrylate (Tg -31 ° C), ethoxylate bis phenol diacrylate (V-700), ethylene glycol dimethacrylate (EDMA), ethylthioethyl methacrylate (Tg -20 ° C), gamma butyrolactone acrylate, glycidyl methacrylate (GMA) (Tg 46 ° C), methoxypolyethylene glycol acrylate, octafluoropentyl acrylate, octafluoropentyl methacrylate, ortho hexahydrophthalic acid, mono methacryloxy ethyl ester (HH) (Tg 70 ° C), pentaerythritol tetraacrylate, pentaerythritol triacrylate, polybutylene glycol dimethacrylate (PBOM), tetraethylene glycol diacrylate (TEGDA) (Tg -40 ° C), tetraethylene glycol ethylene glycol diacrylate (TEGDA) (Tg -30 ° C), tetrahydrofurfuryl acrylate (THFA) (Tg -12 ° C), tetrahydrofurfuryl methacrylate (THFMA) (Tg 60 ° C), triethylene glycol dimethacrylate (3 EDMA), trifluoroethyl acrylate (Tg -10 ° C), trifluoroethyl methacrylate (Tg 80 ° C), trimethylolpropane triacrylate (TMPTA) (Tg 62 ° C), trimethylolpropane trimethacrylate (TMPMA) and tripentaerythritol octaacrylate.

The monomers having (meth) acrylate functions d) are preferably chosen from lauryl acrylate (forming a polymer having a Tg equal to 3 ° C.), tetra (ethylene glycol) di acrylate (forming a polymer having a Tg equal to -40 ° C), trimethylolpropanetriacrylate (forming a polymer having a Tg of 62 ° C), and mixtures thereof.

Of these, lauryl acrylate and tetra (ethylene glycol) diacrylate are preferred. In all cases, it is preferred that the monomers d) are identical.

As for the surfactant e), it is preferably selected from silicone acrylate and glycerol, and mixtures thereof.

Preferably, a silicone acrylate and glycerol will be used.

The stabilizing agent of the silanols g), when present, is chosen from organic and inorganic carboxylic acids having a pka of between 2 and 5 inclusive.

Preferably, the stabilizing agent for silanols is methacrylic acid.

As for the catalyst c), when it is present, it is preferably a photo-catalyst, that is to say a catalyst acting by exposing to UV the formulation containing it.

The acid-generating catalyst that can be used in the invention is chosen from triphenylsulfonium tetrafluoroborate; triphenylsulfonium tetrakis (pentafluorobenzyl) borate; methyldiphenylsulfonium tetrafluoroborate; methyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; dimethylphenylsulfonium hexafluorophosphate; triphenylsulfonium hexafluorophosphate; triphenylsulfonium hexafluoroantimonate; diphenylnaphthylsulfonium hexafluoroarsenate; tritolysulfonium hexafluorophosphate; Panisyldiphenylsulfonium hexafluorantimonate; 4-butoxyphenyldiphenylsulfonium tetrafluoroborate; 4-butoxyphenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; 4-chlorophenyldiphenylsulfonium hexafluoroantimonate; tris (4-phenoxyphenyl) sulfonium hexafluorophosphate; di (4-ethoxyphenyl) methylsulfonium hexafluoroarsenate; 4-acetylphenyldiphenylsulfonium tetrafluoroborate; 4-acetylphenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; tris (4-thiomethoxyphenyl) sulfonium hexafluorophosphate; di (methoxysulfonylphenyl) methylsulfonium hexafluoroantimonate; di (methoxynaphthyl) methylsulfonium tetrafluoroborate; di (methoxynaphthyl) methylsulfonium

tetrakis (pentafluorobenzyl) borate; di (carbomethoxyphenyl) methylsulfonium hexafluorophosphate; (4-octyloxyphényi) diphenylsulfonium tetrakis (3 ₅ 5-bis- trifluoromethylphenyl) borate; tris (dodecylphenyl) sulfonium tetrakis (3,5-bis-trifluoromethylphenyl) borate; 4-acetamidophenyldiphenylsulfonium tetrafluoroborate; 4-acetamidophenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; dimethylnaphthylsulfonium hexafluorophosphate; trifluoromethyldiphenylsulfonium tetrafluoroborate; trifluoromethylidiphenylsulfonium tetrasulfides (pentafluorobenzylborate), phenylmethylbenzylsulfonium hexafluorophosphate, 10-methylphenoxathiinium hexafluorophosphate, 5-methylthianthrenium hexafluorophosphate, 10-phenyl-9,9-dimethylthioxanthenium hexafluorophosphate, 10-phenyl-9-oxothioxanthenium tetrafluoroborate; 10-phenyl-9-oxomioxanmenium tetrakis (pentafluorobenzyl) borate, 5-methyl-10-oxothianthrenium tetrafluoroborate, 5-methyl-10-oxothiantenium tetrakis (pentafluorobenzyl) borate, 4- (4-methylphenyl) 4- (2- methylpropyl) phenyl] iodonium hexafluorophosphate, 5-methyl-0.10-dioxothianthremum hexafluorophosphate, di (dodecylphenyl) iodonium hexafluoroantimonate, di (dodecylphenyl) iodonium triflate, diphenyliodonium bisulfate, 4,4'-dichlorodiphenyliodonium bisulfate, 4 , 4'-dibromodiphenyliodonium bisulfate, 3,3'-dinitrodiphenyliodoniurn bisulfate, 4,4'-dimethyldiphenyliodonium bisulfate; 4,4'-bisulfinimidodiphenyliodonium bisulfate; 3-nitrodiphenyliodonium bisulfate; 4,4'-dimethoxydiphenyliodonium bisulfate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate; (4-octyloxyphenyl) phenyliodonium tetrakis (3,5-bis-trifluoromethylphenyl) borate: (tolylcumyl) iodonium tetrakis (pentafluorophenyl) borate (CH ₃ C ₆ H ₄ ) ₂ I- (S0 ₂ CF ₃ ) 3.

Preferably, (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate is used.

between 10% and 90%, preferably between 30 and 80% of organosilane compound comprising three reactive silyl groups b), between 0 and 10%, preferably between 0 and 7%, and more preferably between 0 and 5%, of polymerization catalyst c),

between 0.1 and 30%, preferably between 0.1 and 20%, more preferably between 0.1 and 10% of monomers having a (meth) acrylate function,

between 15% inclusive and 35% excluded, preferably between 15 and 25%, inclusive, of water f), and

The formulation of the invention may also include organosilane compounds having four, five or six reactive silyl groups and / or a single reactive silyl group.

Organosilane compounds having four hydrolysable silyl groups are, for example, tetraethoxysilane (TEOS) and tetramethoxysilane (TMOS).

Organosilane compounds comprising five or six reactive silyl groups are compounds comprising two silicon atoms to which alkoxide groups are attached.

The organosilane compound having a single reactive group is, for example, 3-glycidoxypropyldimethylethoxysilane (CAS No. 17963-04-1) or methoxytrimethylsilane. (CAS No. 1825-61-2).

It may also include organometallic compounds, metal nanoparticles and other additives as known in the art.

The varnish formulation of the invention makes it possible to obtain a crosslinkable varnish with a high solids content of 50% or even 70%, while maintaining a viscosity typically of less than 10 Cp at room temperature, thanks to the use of specific additives. both at the level of the monomers constituting the matrix of the varnish (formed by the organosilane compounds) that surfactants.

In addition, the surface tension of the varnish remains low, that is to say typically less than 35 mN / m, measured by the method of the D Nouy ring. Thus it is possible to use the crosslinkable lacquer formulation of the invention in a digital ink jet printing process. This was verified on a Dimatix brand printer (model DMP 2800 series) where the 16 injection nozzles were in operation. The ejection of the drops was good and a rectilinear and homogeneous net was formed in the absence of satellite drops.

This printability allows the crosslinkable varnish formulation of the invention to be used for applications where it is necessary to selectively apply to treat certain areas.

Furthermore, the chemical nature of the coating formed by the crosslinkable lacquer formulation of the invention makes it possible to ensure good transparency in the visible range, good chemical resistance, good adhesion to various substrates such as glass, aluminum, polymers such as polycarbonate or polymethylmethacrylate, and good resistance to climatic aging (resistance to UV and moisture).

The invention also provides a method of forming a coating on a surface of a substrate which first comprises hydrolyzing the various previously described components of the varnish formulation.

This hydrolysis is carried out in the water contained in the formulation, by mixing these various components for 48 hours at room temperature.

Then, this mixture is deposited by an ink jet machine, or by any other means such as coating, vaporization, etc. which will occur to those skilled in the art on the surface of the substrate to be coated. Once the desired layer thickness has been obtained, the varnish formulation is crosslinked by exposure to the stress at which the catalyst is sensitive.

In the case where the acid generating catalyst is tetra (ethylene glycol) diacrylate, the stress is exposure to light whose wavelength is the wavelength of the UV.

To better understand the invention, will now be described by way of purely illustrative and non-limiting several modes of implementation. Example 1

A varnish formulation according to the present invention has been formulated by mixing the following compounds:

1 g of methylvinyl diethoxysilane (VMDES, CAS No. 5507 ~ 44 ~ 8 from ALDRICH) (organosilane compound comprising two reactive silyl groups a)),

3.5 g of glycidoxypropyltrimethoxysilane (GPTMS, CAS No. 2530-83-8 from the company ALDRICH) (organosilane compound comprising three reactive silyl groups b)),

- 0,049g Irgacure ^® 250 (CAS No. 344562-80-7 from Ciba) (photocatalyst acid generator c)): (reagent photocatalyst UV, liquid, cationic): (4-methylphenyl) [4 - (2-methylpropyl) phenyl] iodonium hexafluorophosphate,

0.4 g of tetra (ethylene glycol) diacrylate (TEGDA, CAS No. 17831-71-9 from the company ALDRICH) (at least two monomers having acrylate functions d)),

2 g of deionized water (compound f)), acidified with 0.1 g of methacrylic acid (MAA, CAS No. 79-41-4 from the company ALDRICH) (stabilizing agent silanols g)),

- 0,049g TEGO RAD 2100 ^® (from Evonik): silicone acrylate (surfactant e)),

This mixture was placed in a beaker and homogenized with a magnetic stirrer for 48 hours at room temperature.

The obtained varnish formulation was applied to a surface of an aluminum test piece by coating with an Elcometer 4043 film applicator apparatus at a wet thickness of 200 micrometers.

The test piece was photocrosslinked for 10 minutes in a UVACUBE 100 UV irradiator of the Hoenle ^® brand equipped with a 100W mercury vapor lamp (UVA flux 7.3mW / cm ² - UVC 4mW / cm ² ).

At the end of the photocrosslinking, the coating had a thickness of about 30 microns and showed no cracks. In addition, the coating was exposed in an accelerated light aging test in an ATLAS ^® brand enclosure, model SU TEST CPS +, at a light intensity of 760 W / m ² (300-wavelength range). 800nm) for 168 hours.

At the end of this test no crack is observed on the coating.

Finally the application of the varnish of this example by inkjet technology was also evaluated on a printer Dimatix ^® brand, model DMP 2800 series.

All 16 nozzles worked without problems, neither clogging nor formation of satellite drops, the ejection speed of the drops was between 6 and 8m / s.

Example 2

In this example, the weight ratio of organosilane compounds a) and b) was changed from Example 1.

Thus, the mixture of:

2.5 g of methylvinyl diethoxysilane (V DES, CAS No. 5507-44-8 from the company ALDRICH), (organosilane compound comprising two reactive silyl groups a)),

- 1.0 g glycidoxypropyltrimethoxysilane (GPTMS, CAS No. 2530-83-8 from ALDRICH), (organosilane compound comprising three reactive silyl groups b)),

0.039 g of Irgacure 250 (CAS No. 344562-80-7 from the company Ciba) (photocatalyst acid generator c)),

- 0,039g TEGO RAD 2100 ^® (from Evonik): silicone acrylate (surfactant e)) ₅ This mixture was placed in a beaker and homogenized with a magnetic stirrer for 48 hours.

The crosslinkable varnish according to the invention obtained was applied to a surface of an aluminum specimen by coating (Elcometer 4043 film applicator) at a wet thickness of 200 microns.

The varnish was photocrosslinked for 10 minutes in a UV insolator (UVACUBE 100 brand Hoenle ^® ) equipped with a mercury vapor bulb of 100W (UVA flow 7.3mW / cm ² - UVC 4mW / cm ² ).

At the end of the photocrosslinking, the coating had a thickness of about 30 microns and showed no cracks.

The specimen was then exposed, for the coating part at least, to an accelerated light aging test in an ATLAS ^® brand enclosure, model SU TEST CPS +, at a light of 760 W / m ² (length range 300-800nm) for 168 hours.

No crack was observed on the coating at the end of this test.

Example 3

In this example, various organosilane compounds comprising two reactive silyl groups were used.

We mixed in a beaker:

1.0 g of dimethyldimethoxysilane (DMDMS, CAS No. 11-12-39-6 by the company ALDRICH) (organosilane compound having two reactive silyl groups a)),

1.0 g of methylvinyl diethoxysilane (VMDES, CAS No. 5507-44-8 from the company ALDRICH), (organosilane compound having two reactive silyl groups a)),

3.5 g of glycidoxypropyltrimethoxysilane (GPTMS, CAS No. 2530-83-8 from the company ALDRICH), (organosilane compound having three reactive silyl groups b)),

0.070 g of Irgacure 250 (CAS No. 344562-80-7 from the company Ciba) (photocatalyst acid generator c)),

2 g of deionized water ((component f)),

- 0.1 g of methacrylic acid (MAA, CAS No. 79-41 -4 ALDRICH) (stabilizer silanol _g))} 0.070 g of TEGO RAD 2100 (from the company Evonik) (surfactant e)) (silicone acrylate),

0.4 g of trimethylol propane triacrylate (TMPTA, CAS No. 15625-89-5 from the company ALDRICH) (at least two monomers having acrylate functions d)),

The mixture was placed in a beaker and homogenized with a magnetic stirrer for 48 hours.

The resulting varnish formulation was applied to a surface of an aluminum test specimen by coating (Elcometer 4043 film applicator) at a wet thickness of 200 micrometers.

The formulation was photocrosslinked for 10 minutes in a UV insolator (UVACUBE 100 brand Hoenle ^® ) equipped with a mercury vapor bulb of 100W (flow UVA 7.3mW / cm ² - UVC 4mW / cm ² ).

The specimen was then exposed for the coating portion to an accelerated light aging test in an ATLAS ^® SUNTEST CPS + brand enclosure at a light intensity of 760 W / m ² (300-wavelength range). 800nm) for 168 hours.

No crack was observed on the coating at the end of this test.

Example 4

This example shows the effect of the Tg of the polymer corresponding to the organic monomers on the cracking.

Several varnish formulations according to the present invention have been formulated by mixing the following compounds:

1 g of dimethyldimethoxysilane (DMDMS, CAS No. 112-39-9 from the company ALDRICH) (organosilane compound comprising two reactive silyl groups a)),

1 μg of methylvinyl dimethoxysilane (VMDMS, CAS No. 16753-62-1 from the company ALDRICH) (organosilane compound comprising two reactive silyl groups a)), 3.5 g of glycidoxypropyltrimethoxysilane (GPTMS, CAS No. 2530-83-8 from the company ALDRICH) (organosilane compound comprising three reactive silyl groups b)),

acrylate monomer or monomer mixture having an acrylate function a): different compositions have been tested to demonstrate the effect of the glass transition temperature of the corresponding polymer on the cracking of the varnish),

- 0,070g Irgacure ^® 250 (CAS No. 344562-80-7 from Ciba) (photocatalyst acid generator c)): (reagent photocatalyst UV, liquid, cationic) ((4-methylphenyl) [4 (2-methylpropyl) phenyl] iodonium hexafluorophosphate),

2 g of deionized water (compound f)), acidified with methacrylic acid (MAA, CAS No. 79-41-4 from the company ALDRICH) (stabilizing agent silanols g)),

0.070 g of TEGO RAD 2100 (from the company Evonik): silicone acrylate (surfactant e)) ₅

These mixtures were placed in a beaker and homogenized with a magnetic stirrer for 48 hours at room temperature.

The resulting varnish formulations were applied to the surface of aluminum test pieces by coating with an Elcometer 4043 film applicator apparatus at a wet thickness of 200 micrometers.

The test pieces were photocrosslinked for 10 minutes in a UVACUBE 100 UV irradiator of the Hoenle ^® brand equipped with a 100W mercury vapor bulb (UVA flux 7.3mW / cm ² - UVC 4mW / cm ² ).

At the end of the photocrosslinking, the coatings had a thickness of about 30 micrometers

In addition, the coatings were exposed in an accelerated light aging test in an ATLAS ^® brand SUNTEST CPS + cabinet, at a light intensity of 760 W / m ² (300-800nm wavelength range). ) for 168 hours.

The table below summarizes for each acrylate monomer composition the appearance or not of cracks on the specimens: No. Organic monomers Tg of the polymer Presence of cracks after corresponding test aging SU TEST

1 TEDGA - 0.4g -40 ° C No

2 TEGDA - 0.2g -40 ° C No

LA - 0.2g + 15 ° C

3 LA - 0.4g + 15 ° C No

4 TMPTA - 0.4g + 62 ° C No

5 TEGDA - 0.2g -40 ° C No

TMPTA - 0.2g + 62 ° C

6 MAA - 0.4g + 228 ° C Yes

with:

TEGDA = tetra (ethylene glycol) diacrylate (CAS No. 17831 -71-9 from the company ALDRICH)

LA = Lauryl acrylate (CAS No. 2156-97-0 from the company ALDRICH)

TMPTA = trimethylolpropane triacrylate (CAS No. 15625-89-5 from the company ALDRICH)

MAA = methacrylate acid (CAS No. 79-41-4 from the company ALDRICH)

Example 5

In this example, an organosilane compound comprising four reactive silyl groups was used.

We mixed in a beaker:

1 g dimethyldimethoxysilane (DMDMS, CAS No. 112-39-6 from the company ALDRICH) (organosilane compound having two reactive silyl groups a)),

1 μg of methylvinyl dimethoxysilane (VMDMS, CAS No. 16753-62-1 of ALDRICH), (organosilane compound having two reactive silyl groups a))

- lg of tetraethoxysilane (TEOS, CAS No. 78-10-4 of the company

ALDRICH)

0.070 g of Irgacure 250 (CAS No. 344562-80-7 from Ciba) (photocatalyst acid generator c)), - 2 g of deionized water (component f)) _s

0.1 g of methacrylic acid (MAA, CAS No. 79-41-4 from the company ALDRICH) (stabilizing agent silanols g)),

0.070 g of TEGO RAD 2100 (from the company Evonik) (surfactant e)) (silicone acrylate),

At the end of the photocrosslinking, the coating had a thickness of about 30 microns and showed no cracks. Its appearance was always colorless transparent.

The specimen was then exposed for the coating portion to an accelerated light aging test in an ATLAS ^® SUNTEST CPS + brand enclosure at a light intensity of 760 W / m ² (300-wavelength range). 800nm) for 96 hours.

No crack was observed on the coating at the end of this test.

Example 6

This example shows that it is possible to incorporate nanoparticles in the varnish without altering its properties. The purpose of the latter is to provide complementary properties: improvement of hardness, improvement of resistance to aging (using UV absorbers).

We mixed in a beaker:

1.0 g of dimethyldimethoxysilane (DMDMS, CAS No. 112-39-6 from the company ALDRICH) (organosilane compound having two reactive silyl groups a)), 1.0 g of methylvinyl diethoxysilane (VMDES, CAS No. 5507-44-8 from the company ALDRICH), (organosilane compound having two reactive silyl groups a)),

1 g of deionized water (component f)),

1 g of an aqueous solution of ZnO nanoparticles

(monodisperse granulometry around 20nm, dialyzed solution with 13% by mass in nanoparticles)

The specimen was then exposed for the coating part to an accelerated light aging test in an ATLAS ^® brand enclosure. model SUNTEST CPS +, at a light of 760 W / m ² (range of wavelength 3O0-8O0nm) for 168 hours.

No crack was observed on the coating at the end of this test.

Example 7

In this example, the procedure was as in Example 1 except that there was further introduced an organosilane compound comprising a single reactive silyl group, 3-glycidoxypropyldimethylethoxysilane.

Thus, a varnish formulation according to the present invention has been formulated by mixing the following compounds:

1 g of methylmethyl dimethoxysilane (VMDMS, CAS No. 16753-62-1 from the company ALDRICH) (organosilane compound comprising two silyl groups (a)),

3.5 g glycidoxypropyltrimethoxysilane (GPTMS, CAS No. 2530-83-8 from the company ALDRICH) (organosilane compound comprising three reactive silyl groups b)),

0.5 g of dimethyldimethoxysilane (DMDMS, CAS No. 112-39-6 from the company ALDRICH) (organosilane compound comprising a reactive silyl group),

0.5 g of 3-glycidoxypropyldimethylethoxysilane (GPDMES, CAS No. 17963-04-1) (organosilane compound comprising a reactive silyl group),

0.07 g of Irgacure 250 (CAS No. 344562-80-7 from the company Ciba)

(photo acid generating catalyst c)): (photocatalyst UV reactive, liquid, cationic): (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate,

2 g of deionized water (compound f) acidified with 0.1 g of methacrylic acid (MAA, CAS No. 79-41 -4 from the company ALDRICH) (stabilizing agent silanols g)). This mixture was placed in a beaker and homogenized with a magnetic stirrer for 48 hours at room temperature.

The resulting varnish formulation was applied to a surface of an aluminum specimen by coating with an Elcometer 4043 film applicator apparatus at a wet thickness of 200 micrometers.

In addition, the coating was exposed in an accelerated light aging test in an ATLAS ^® brand SUNTEST CPS + cabinet at a light output of 760 W / m ² (300-800nm wavelength range). ) for 600 hours.

At the end of this test, no crack was observed on the coating.

Comparative Example 1

For comparison, a varnish formulation according to EP 1 238 024, but also containing the acrylate monomers a), was formulated and tested.

For this, we mixed in a beaker:

1 g of methylvinyl diethoxysilane (VMDES, CAS No. 5507-44-8 from the company ALDRICH) (organosilane compound comprising two reactive silyl groups a)), 3.5 g of glycidoxypropyltrimethoxysilane (GPTMS, CAS No. 2530-83-8 from the company ALDRICH) (organosilane compound comprising three reactive silyl groups b)),

0.049 g of Irgacure 250 (CAS No. 344562-80-7 from Ciba) (acid-generating catalyst c)),

0.4 g of lauryl acrylate (CAS No. 2156-97-0 from the company ALDRICH) (at least two monomers having an acrylate function d)),

The mixture was homogenized using a magnetic stirrer. The resultant formulation was applied to a surface of an aluminum test piece by coating (Eicometer 4043 film applicator) to a wet thickness of 200 microns.

The specimen was placed in a UV collector (UVACUBE 100 brand Hoenle ^® ) equipped with a mercury vapor bulb of 100W (UVA flux 7.3mW / cm2 - UVC 4mW / cm) to photocreat the coating. This sunstroke lasts 10 minutes.

At the end of this photocrosslinking, the coating had a thickness of about 30 microns and already had many cracks.

It can be seen from Example 1 and Comparative Example 1 that the presence of a surfactant and the pre-hydrolysis (presence of water) of organosilane compounds having two or three reactive silyl groups, and the presence of stabilizing agent silanols, can significantly improve the properties of the coating obtained.

Comparative Example 2

In this example, a formulation according to the invention was used but without silane compounds having two reactive silyl groups a).

For this, we mixed in a beaker:

5 g of glycidoxypropyltrimethoxysilane (GPTMS, CAS No. 2530-83-8 from the company ALDRICH) (organosilane compound comprising three reactive silyl groups b)),

2 g of deionized water (component f)), and acidified with methacrylic acid (MAA, CAS No. 79-41-4 from the company ALDRICH) (stabilizing agent silanols g)), 0.4 g of tetra (ethylene glycol) diacrylate (TEGDA, CAS No. 17831 ~ 71-9 from the company ALDRICH) (minus two monomers having acrylate functions d)),

0.054 g of Irgacure 250 (CAS No. 344562-80-7 from the company Ciba) (acid-generating catalyst c)),

0.054 g of TEGO RAD 2100 (from the company Evonik) (surfactant e)).

This mixture was homogenized for 48 hours at room temperature using a magnetic stirrer.

The formulation was applied to a surface of an aluminum specimen by coating (Eicometer 4043 film applicator) to a wet thickness of 200 microns.

The test piece was photocrosslinked for 10 minutes in a UV insolator (UVACUBE 100 brand Hoenle *) equipped with a mercury vapor bulb of 100W (UVA flux 7.3mW / cm2 - UVC 4mW / cm2).

At the end of the photocrosslinking, the coating had a thickness of about 30 microns and showed no crack.

This coating was exposed to an accelerated light aging test in an ATLAS ^® brand enclosure, model SU TEST CPS +, at a light of 760 W / m2 (range 30O-800nm) for 168h.

The presence of several cracks was observed at the end of this test. Comparing this Comparative Example 2 with Example 1, it is seen that it is necessary to use in combination an organosilane compound comprising two reactive silyl groups and an organosilane compound comprising three reactive silyl groups so that the coating has a good performance at aging in the light.

Comparative Example 3

Compared to Example 1, this example aims to show that it is necessary to formulate a varnish with a surfactant not to cause cracking of the coating. The formulation below is identical to that of Example 1, but does not include surfactant. We mixed in a beaker: 3.5 g of glycidoxypropyltrimethoxysilane (GPTMS, CAS No. 2530-83-8 from the company ALDRICH) (organosilane compound comprising three reactive silyl groups b)),

1.0 g of methylvinyl diethoxysilane (VMDES, CAS No. 5507-44-8 from the company ALDRICH) (organosilane compound comprising two reactive silyl groups a)),

2 g of deionized water (component d)), and acidified with methacrylic acid (MAA, CAS No. 79-41-4 from the company ALDRICH) (stabilizing agent silanols g)),

- 0 _; 4 g of tetra (ethylene glycol) diacrylate (TEGDA, CAS No. 17831-71-9 from the company ALDRICH) (at least two monomers having acrylate functions f)),

0.049 g of Irgacure 250 (CAS No. 344562-80-7 from Ciba) (acid-generating catalyst c)).

This mixture was homogenized with a magnetic stirrer for 48 hours at room temperature.

The formulation was applied, on a green aluminum test, by coating (Elcometer 4043 film applicator) to a wet thickness of 200 micrometers.

The coating of the test specimen was photocrosslinked for 10 minutes in a UV insoluator (UVACUBE 100 brand Hoenle ^® equipped with a mercury vapor bulb of 100W (UVA flux 7.3mW / cm 2 - UVC 4mW / cm 2).

The coating was exposed to an accelerated light aging test in an ATLAS ^® brand SUNTEST CPS + chamber at a light of 760 W / m2 (300-800nm range) for 168 hours.

The presence of several cracks was observed at the end of this test.

Comparative Example 4

Formulations made on the basis of the formulation of Example 3, replacing the VMDES by methylvinyl dimethoxysilane (VMDMS, CAS No. 1 6753-62-1 by the company ALDRICH) as an organosilane compound having two reactive silyl groups a). In these formulations, the weight% of water, relative to the total mass of the crosslinkable varnish was adjusted to evaluate its influence on the cracking of the varnish. The formulations were applied and tested under the same conditions as those described in Example 3: the results are summarized in the table below.

Comparative Example 5

A formulation according to the French patent application No. 2,886,309, that is to say containing an acrylate polymer already formed has been manufactured.

This formulation was developed on the basis of Example No. 3 keeping identical the molar number of acrylate units had the following composition:

1.0 g dimethyldimethyloxysilane (DMDMS, CAS No. 1112-39-6 from the company ALDRICH) (organosilane compound having two reactive silyl groups a)),

1.0 g of methylvinyl dimethoxysilane (VMDMS, CAS No. 16753-62-1 from the company ALDRICH), (organosilane compound having two reactive silyl groups a)),

- 3.5 g of glycidoxypropyltrimethoxysilane (GPTMS, CAS No. 2530-83-8 from the company ALDRICH), (organosilane compound having three reactive silyl groups b)),

- 2g of deionized water ((component f)) _} 0.1 g of methacrylic acid (MAA, CAS No. 79-41-4 from the company ALDRICH) (stabilizing agent silanols g)),

- 0.4g of polyacrylic acid (PAA, CAS No. 9003-01-4 of the company

Aldrich).

This formulation (PAA-1) had a very high viscosity and quickly became en masse in the container. Another formulation was obtained by decreasing the amount of polyacrylic acid to 0.2 g in the above formula. This latter formulation (PAA-2) had a very high viscosity of 385cP which made it unsuitable for use with an ink jet printer. Indeed, for the ink to be used in inkjet printing, it is very important that it has a maximum viscosity of 70cP.

Furthermore, after photocrosslinking and drying, the porosity measurements made ("ethanol porosimetry" method) on the PAA-2 sample show a greater porosity (21%) than that obtained on the same formula by replacing the polyacrylic acid with trimethylol propane triacrylate (CAS No. 5625-89-5) (13%). The use of preformed acrylate polymer thus risks rendering the varnish more sensitive to aging in climatic conditions, the moisture thus being able to infiltrate more easily into the coating and thus cause hydrolysis reactions to weaken it.

Claims

1. Crosslinkable lacquer formulation comprising:

a) at least one organosilane compound comprising two reactive silyl groups,

b) at least one organosilane compound comprising three reactive silyl groups,

c) optionally a polymerization catalyst of at least compounds a) and b),

d) at least two monomers having a (meth) acrylate function, e) at least one surfactant,

f) water, and

g) optionally at least one silanol stabilizing agent, characterized in that the monomers having a (meth) acrylate function d) are chosen from lauryl acrylate, tetra (ethylene glycol) diacrylate, trimethylolpropane triacrylate, and mixtures of these, preferably monomers d) are identical and are selected from the monomers tetra (ethylene glycol) diacrylate and trimethylol propane triacrylate.

2. Formulation according to claim 1, characterized in that the surfactant is selected from a silicone acrylate and glycerol and mixtures thereof, preferably is a silicone acrylate.

3. Formulation according to claim 1 or 2, characterized in that the silanols stabilizing agent g) is chosen from organic or inorganic carboxylic acids having a pKa of between 2 and 5 inclusive, preferably the stabilizing agent silanols g. ) is selected from acetic acid, valeric acid, stearic acid and methacrylic acid, most preferably methacrylic acid.

4. Formulation according to any one of the preceding claims, characterized in that the organosilane compound comprising two reactive silyl groups a) has the generic formula Z ^] Z ² SiZ ³ Z ⁴ in which:

Z and Z are identical or different and represent non-reactive silyl groups, preferably chosen from linear or branched, optionally substituted, optionally cyclic, Ci-Cso alkyls having optionally double or triple bond unsaturations or aromatic groups, and

Z ³ and Z ⁴ are identical or different, and represent reactive silyl groups, preferably chosen from halogen, in particular chlorine, and a group OR, in which R preferably represents linear or linear C 1 -C 5 alkyl; branched, optionally substituted, optionally cyclic, optionally having unsaturations of the double type, or triple bond or aromatic group,

preferably the organosilane compound a) is selected from alkoxy and / or hydroxy terminated polydimethylsiloxanes having a molecular weight of 400 to 150,000; alkoxy and / or hydroxy terminated diphenylsiloxane dimethylsiloxane copolymers; alkoxy and / or hydroxy terminated polydiphenylsiloxanes; hydroxysilyl and / or alkoxysilyl terminated polytrifluoropropylmethylsiloxanes, polyesters, polyurethanes, and polyacrylates; dialkyl-substituted dialkyl- and dialkoxy-silanes, such as diethyldiethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane, diisobutyldimethoxysilane, dimfldiethoxysilane, diisopropyldimethoxysilane, bis (3-cyanopropyl) dimethoxysilane, (2-chloroethyl) methyldimethoxysilane, chlorométhylméthyldiéthoxysilane, (2-chloroethyl) méthyldiisopropoxysilane, the (3-chloropropyl) methyldimethoxysilane, (3-cyanopropyl) methyldimethoxysilane, cyclohexyléthyldiméthoxysilane the dodécylméthyldiéthoxysilane, risobutylméthyldiméthoxysilane, 3-mercaptopropylmethyldimethoxysilane, diethylsilane mercaptométhylméthyl the méthacryîoxypropylméthylidiéthoxysilane, the methacryloxypropylmethyldimethoxysilane, methyldiethoxysilane, methyldimethoxysilane, n-octadecylmethyldiethoxysilane; n-octylmethyldiethoxysilane, dicyclopentyldimethoxysilane; substituted aryl and diaryl alkoxysilanes, such as diphenyldimethoxysilane, phenyldiethoxysilane, phenylmethyldiethoxysilane, phenylmethyldimethoxysilane; substituted hydroxysilyl and alkoxysilyl arenes such as 1,4-bis (hydroxydimethylsilyl) benzene, 1,3-bis (methoxydimethylsilyl) benzene; substituted trialkylsilyl alkoxysilanes, such as bis (trimethylsilylmethyl) dimethoxysilane, trimethylsilylmethyl- dimet oxysilane; cyclic alkoxysilanes, such as 1,1-diethoxy-1-silacyclopent-3-ene; substituted acyloxy silanes such as dimethyldiacetoxysilane, vinylmethyldiacetoxysilane, diethylbenzoyloxyacetoxysilane; geminal silanediols, such as diphenylsilanediol, dicyclohexylsilanediol; substituted alkyl and / or aryl substituted cyclic siloxanes, such as 3- (3,3,3-trifluoropropyl) heptamethyltrisiloxane, hexamethyltrisiloxane, octamethyltetrasiloxane; Substitutes alkenyl alkoxysilanes, such as vinylmethyldiethoxysilane, vinylmethyldimethoxysilane, the vinylphényldiéthoxysilane, 3-glycidoxypropyldiméthoxyméthylsilane the diméthyldiclilorosilane the dichlorotetramétbyldisiloxane the dichlorohexaméthyltrisiloxane, bis (triméthylsiIoxy) dichlorosilane, the éthylméthyldichlorosilane the propylmethyldichlorosilane,

1 'hexaméthyldichlorosilane the heptylniéthyldichlorosilane the octylmethyldichlorosilane, the décylméthyldichlorosilane the dodecylmethyldichlorosilane the octadécylméihyldichlorosilane, risopropylméthyldichlorosïlane, t-butylméthyldichîorosilane the cyclohexylméthyldichlorosilane, phenylmethyldichlorosilane, the phènéthylméthyldichlorosilane, (3-phenylpropyl) méthyldichîorosilane, 4- phénylbutylméthyldichlorosilane phenoxypropylmethyldichlorosilane, 3- (p-methoxyphenyl) propylmethyldiillosilane, diethyldichlorosilane, diisopropyldichlorosilane, di-n-butyldichlorosilane, dicyclopentyldichlorosilane, di-n-hexyldichlorosilane and di-n-octyl dichlorosilane, and mixtures thereof. it is preferably vinylmethyldiethoxysilane.

5. Formulation according to any one of the preceding claims, characterized in that the organosilane compound comprising three reactive silyl groups b) has the formula Z ¹ SiZ ³ Z ⁴ Z ⁵ in which Z ¹ is a non-reactive silyl group, preferably a linear or branched, optionally substituted, optionally cyclic C1-C50 alkyl group, optionally comprising double or triple bond type or aromatic group unsaturations, and ZZ ⁴ and Z ⁵ are identical or different, and are reactive silyl groups; , preferably chosen from halogen, in particular chlorine, and a group OR ⁵ in which R ⁵ is preferably linear or branched C ⁵ -C ⁵ alkyl, optionally substituted, optionally cyclic, optionally comprising unsaturations of the double type, or triple bond or aromatic group,

preferably the organosilane compound having a reactive silyl group b) is selected from risobutyltriméthoxysilane the méthytriéthoxysilane the méthytriméthoxysilane, octyltriethoxysilane, propyltrimethoxysilane, phenyltrimethoxysilane, chloropropyltriethoxysilane, chloroproyltriméthoxysilane, mercaptopropyltrimethoxysilane, glycidyloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, the vinyltriéthoxysiîane, the vinyltrimethoxysilane, methyltrichlorosilane, triméthylsiloxytrichlorosilane the éthyrtrichlorosilane, propyltrichlorosilane, n- butyltrichlorosilane, the pentyltrichlorosilane the hexyltrichlorosilane, heptyltrichlorosilane, octyltrichlorosilane, the décyltrichlorosilane, rundécyltrichlorosilane the dodécyltrichlorosilane the tétradécyltrichlorosilane, rhexadécyltrichlorosilane, roctadécyltrichlorosilane, the eicosylirichlorosilane, isobutyltrichlorosilane, cyclopentyltrichlorosilane, (3,3-dimethyl thylbutyl) trichlorosilane, bicycloheptyltrichlorosiiane, risooctyltrichlorosilane, radamantyléthyltrichlorosilane, (di-n-octylméthylsilyl) éthyltrichlorosiiane, phenyltrichlorosilane, benzyltrichlorosilane the the phènéthyltrichlorosilane, 4- phénylbutyltrichlorosilane the phénoxypropyltrichlorosilane the phénoxyundécyltrichlorosilane, the (l-naphthylmethyl) trichlorosilane and mixtures thereof, preferably is glycidyloxypropyltrimethoxysilane.

6. Formulation according to any one of the preceding claims, characterized in that the polymerization catalyst c) is selected from triphenylsulfonium tetrafluoroborate; triphenylsulfonium tetrakis (pentafluorobenzyl) borate; methyldiphenylsulfonium tetrafluoroborate; methyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; dimethylphenylsulfonium hexafluorophosphate; triphenylsulfonium hexafluorophosphate; triphenylsulfonium hexafluoroantimonate; diphenylnaphthylsulfonium hexafluoroarsenate; tritolysulfonium hexafluorophosphate; anisyldiphenylsulfonium hexafluorantimonate; 4-butoxyphenyldiphenylsulfonium tetrafluoroborate; 4-butoxyphenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; the 4- chlorophenyldiphenylsulfonium hexafluoroantimonate;

phenoxyphenyl) sulfonium hexafluorophosphate;

oxyphenyl) ethylsulfonium hexafluoro arsenate;

acetylphenyldiphenylsulfonium tetrafluoroborate; 4-acetylphenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; tris (4-thiomethoxyphenyl) sulfonium hexafluorophosphate; di (methoxysulfonylphenyl) methylsulfonium hexafluoroantimonate; di (methoxynaphthyl) methylsulfonium tetrafluoroborate; di (methoxynaphthyl) methyl sulfonium tetrakis (pentafluorobenzyl) borate; di (carbomethoxyphenyl) methylsulfonium hexafluorophosphate; (4-octyloxyphenyl) diphenylsulfonium tetrakis (3,5-bis-trifluoromethylphenyl) borate; tris (dodecylphenyl) sulfonium tetrakis (3,5-bis-trifluoromethylphenyl) borate; 4-acetamidophenyldiphenylsulfomuretetrafluoroborate; 4-acetamidophenyl diphenyl sulfonium tetrakis (pentafluorobenzyl) borate; dimethylnaphthylsulfonium hexafluorophosphate; trifluoromethyldiphenyl sulfonium tetrafluoroborate; trifluoromethyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; phenylmethylbenzylsulfonium hexafluorophosphate; 10-methylphenoxathiinium hexafluorophosphate; 5-methylthianthrenium hexafluorophosphate; 10-phenyl-9,9-dimethylthioxanthenium hexafluorophosphate; 10-phenyl-9-oxothioxanthenium tetrafluoroborate; 10-phenyl-9-oxothioxanthenium tetrakis (pentafluorobenzyl) borate; 5-methyl-10-oxothianthrenium tetrafluoroborate; 5-methyl-10-oxothiantenium tetrakis (pentafluorobenzyl) borate; (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate; 5-methyl-10,10-dioxothianthrenium hexafluorophosphate, di (dodecylphenyl) iodonium hexafluoroantimonate, di (dodecylphenyl) iodonium triflate; diphenyliodonium bisulfate, 4,4'-dichlorodiphenyliodonium bisulfate; 4,4 '= dibromodiphenyliodonium bisulfate; the 3 _? 3'-diniti diphenyliodonium bisulfate; 4,4'-dimethyldiphenyliodonium bisulfate; 4,4'-bisuccinimidodiphenyliodonium bisulfate; 3-nitrodiphenyliodonium bisulfate; 4,4'-dimethoxydiphenyliodonium bisulfate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate; (4-octyloxyphenyl) phenyliodonium tetrakis (4-bis-trifluoromethylphenyl) borate: (tolylcumyl) iodonium tetrakis (pentafluorophenyl) borate (CH ₃ C ₆ H ₄ ) ₂ 1- (SO ₂ CF ₃ ) _3, Preferably, it is (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate.

7. Formulation according to any one of the preceding claims, characterized in that it comprises in mass%, relative to the total mass of the formulation:

8. Formulation according to any one of the preceding claims, characterized in that it further comprises at least one organosilane compound comprising from 4 to 6 reactive silyl groups and / or at least one organosilane compound comprising a reactive silyl group.

9. Formulation according to any one of the preceding claims, characterized in that it further comprises particles of micrometric or nanometric size, of an oxide selected from TiO ₂ , SiO ₂ , ZnO and mixtures thereof. this.

10. A method of depositing a layer of varnish on the surface of a substrate, comprising the following steps:

A) mixture of at least one organosilane compound comprising two reactive silyl groups a), at least one organosilane compound comprising three reactive silyl groups b), a polymerization catalyst c), water f), at least one surfactant e), at least two monomers having a (meth) acrylate function d), and a silanol stabilizing agent (g) for 24 to 48 hours at room temperature,

B) deposit, preferably by ink jet, of the mixture obtained in step

A) on the surface of a substrate,

characterized in that the at least two monomers having a function (meth) acrylate d) are selected from lauryl acrylate, tetra (ethylene glycol) diacrylate, trimethylol propane triacrylate, and mixtures thereof, preferably the monomers are identical and are selected from tetra (ethylene glycol) diacrylate and trimethylol propane triacrylate.

11. A method of depositing a varnish layer according to claim 10, characterized in that the surfactant e) is selected from a silicone acrylate, glycerol and mixtures thereof, preferably is a silicone acrylate.

12. A method of depositing a varnish layer according to claim 10 or 1 1, characterized in that the silanols stabilizing agent is selected from organic or inorganic carboxylic acids having a pka of between 2 and 5 inclusive, preferably the stabilizing agent silanols g) is selected from acetic acid, valeric acid, stearic acid and methacrylic acid, most preferably methacrylic acid.

13. A method of depositing a varnish layer according to any one of claims 10 to 12, characterized in that the organosilane compound comprising two reactive silyl groups a) has the generic formula Z ^! Z ² SiZ ³ Z ⁴ in which:

Z and Z are identical or different and represent non-reactive silyl groups, preferably chosen from linear or branched, optionally substituted, optionally cyclic, C-C 50 alkyls, optionally having double or triple bond type unsaturations, or aromatic groups, and

Z ³ and Z ⁴ are identical or different and represent reactive silyl groups, preferably chosen from a halogen, in particular the chlorine, and a group OR ³ , in which R ³ represents preferably a linear or branched, optionally substituted, optionally cyclic C 1 -C 50 alkyl, optionally having unsaturations of the double type, or triple bond or aromatic group,

preferably the organosilane compound a) is selected from alkoxy and / or hydroxy terminated polydimethylsiloxanes having a molecular weight of 400 to 150,000; alkoxy and / or hydroxy terminated diphenylsiloxane dimethylsiloxane copolymers; alkoxy and / or hydroxy terminated polydiphenylsiloxanes; hydroxysilyl and / or alkoxysilyl terminated polytrifluoropropylmethylsiloxanes, polyesters, polyurethanes, and polyacrylates; dialkyl-substituted dialkyl- and dialkoxy-silanes, such as diethyldiethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane, diisobutyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, bis (3-cyanopropyl) dimethoxysilane, (2-chloroethyl) methyldimethoxysilane, the chlorométhylméthyldiéthoxysilane, (2-chloroéthyî) méthyldiisopropoxysilane, the (3-chloropropyl) methyldimethoxysilane, (3-cyanopropyl) methyldimethoxysilane, cyclohexyîéthyldiméthoxysilane the dodécylméthyldiéthoxysilane, risobutylméthyldiméthoxysilane, 3-mercaptopropylmétl yldiméthoxysilane, diethylsilane mercaptométhylméthyl the méthacryloxypropylméthylidiéthoxysilane, the methacryloxypropylmethyldimethoxysilane, methyldiethoxysilane, methyldimethoxysilane, n-octadecylmethyldiethoxysilane; n-octylmethyldiethoxysilane, dicyclopentyldimethoxysilane; substituted aryl and diaryl alkoxysilanes, such as diphenyldimethoxysilane, phenyldiethoxysilane, phenylmethyldiethoxysilane, phenylmethyldimethoxysilane; substituted hydroxysilyl and alkoxysilyl arenes such as 1,4-bis (hydroxydimethylsilyl) benzene, 1,3-bis (methoxydimethylsilyl) benzene; substituted trialkylsilyl alkoxysilanes, such as bis (trimethylsilylmethyl) dimethoxysilane, trimethylsilylmethyl-dimethoxysilane; cyclic alkoxysilanes, such as 1,1-diethoxy-1-silacydopent-3-ene; substituted acyloxy silanes such as dimethyldiacetoxysilane, vinylmethyldiacetoxysilane, diethylbenzoyloxyacetoxysilane; geminal silanediols, such as diphenylsilanediol, dicyclohexylsilanediol; substituted alkyl and / or aryl substituted cyclic siloxanes, such as 3- (3,3,3-trifluoropropyl) heptamethyltrisiloxane, hexamethyltrisiloxane, octamethylketrasiloxane; Substitutes alkenyl alkoxysilanes, such as vinylmethyldiethoxysilane, the vinylméthyldimétlioxysilane the vinylphényldiéthoxysilane, 3-glycidoxypropyldiméthoxyméthylsilane, dimethyldichlorosilane, dichlorotetraméthyldisiloxane the dichlorohexaméthyltrisiloxane, bis (trimethylsiloxy) dichlorosilane, éthylméthyldichlorosilane the propylmethyldichlorosilane, the hexaméthyldichlorosilane, rheptylméthyldichlorosilane, octylmethyldichlorosilane, the décylméthyldichlorosilane the dodecylmethyldichlorosilane the octadecyln ethyldichlorosilane, the isopropylméthyldichlorosilane, t-butylméthyldichlorosilane the cyclohexylméthyldichlorosilane, phenylmethyldichlorosilane, the phènéthylméthyldichlorosilane, (3-phenylpropyl) methyldichlorosilane ₅ 4- phénylbutylméthyldichlorosilane the phénoxypropylméthyldichlorosilane, 3- (p methoxyphenyl) propylmethyldichlorosilane, diethyldichlorosilane, diisopropyldichlorosilane, di-nb utyldichlorosilane, dicyclopentyldichlorosilane, di-n-hexyldichlorosilane and di-n-octyldichlorosilane, and mixtures thereof, preferably is vinylmethyldiethoxysilane.

14. A process for depositing a varnish layer according to any one of claims 10 to 13, characterized in that the organosilane compound comprising three reactive silyl groups b) has the formula Z ¹ SiZ ³ Z ⁴ Z ⁵ in which Z ¹ is a non-reactive silyl group, preferably a linear or branched, optionally substituted, optionally cyclic C ₁ -C 50 alkyl group, optionally comprising unsaturations of the double type, or triple bond or aromatic group, and Z ³ , Z ^4; and Z ⁵ are the same or different, and are reactive silyl groups, preferably selected from halogen, in particular chlorine, and a group OR ⁵ in which R ⁵ is preferably straight or branched C1-C10 alkyl, optionally substituted, optionally cyclic, optionally comprising unsaturations of the double type, or triple bond or aromatic group, preferably the organosilane compound having a reactive silyl group b) is selected from isobutyltrimethoxysilane, the méthytriéthoxysilane the méthytriméthoxysilane, octyltriethoxysilane, propyltrimethoxysilane, phenyltrimethoxysilane, chloropropyltriethoxysilane, chloroproyltriméthoxysilane, the mercaptopropyltrimethoxysilane, gîycidyloxypropyltriméthoxysilane, methacryloxypropyltrimethoxysilane, vinyltriethoxysilane vinyltrimethoxysilane, methyltrichlorosilane, trimethylsiloxytrichlorosilane, ethyltrichlorosilane, propyltrichlorosilane, n-butyltrichlorosilane, pentyltrichlorosilane, hexyltrichlorosilane, heptyltrichlorosilane, octylirichlorosilane, decyltrichlorosilane, undecyltrichlorosilane, dodecyltrichlorosilane, tetradecyltrichlorosilane, hexadecyltrichlorosilane, octadecyltrichlorosilane, eicosyltrichlorosilane, risobutyltrichlorosilane, cyclopentyltrichlorosilane, diméthylbutyî) trichlorosilane, bicycloheptyltrichlorosilane, risooctyltrichlorosilane the adamantyléthyltrichlorosilane, (di-n-octylméthylsilyl) ethyltrichlorosilane, phenyltrichlorosilane, benzyltrichlorosilane the the phènéthyltrichlorosilane, 4- phénylbutyltrichlorosilane the phénoxypropyltrichlorosilane the phénoxyundécyltrichlorosilane, the (l-naphthylmethyl) trichlorosilane and mixtures thereof, preferably is glycidyloxypropyltrimethoxysilane.

15. A method of depositing a varnish layer according to any one of claims 10 to 14, characterized in that the polymerization catalyst c) is selected from triphenylsulfonium tetrafluoroborate; triphenylsulfonium tetrakis (pentafluorobenzyl) borate; methyldiphenylsulfonium tetrafluoroborate; methyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; dimethylphenylsulfonium hexafluorophosphate; triphenylsulfonium hexafluorophosphate; triphenylsulfonium hexafluoroantimonate; diphenylnaphthylsulfonium hexafluoroarsenate; tritolysulfonium hexafluorophosphate; anisyldiphenylsulfonium hexafluorantimonate; 4-butoxyphenyldiphenylsulfonium tetrafluoroborate; 4-butoxyphenyldiphenylsulfonium tetrakis (pentafluorobenzyl) borate; 4-chlorophenyldiphenylsulfonium hexafluoroantimonate; tris (4-phenoxyphenyl) sulfonium hexafluorophosphate; the di (4- ethoxyphenyl) methylsulfonium hexafluoroarsenate; 4-acetylphenyldiphenylsulfonium tetrafluoroborate; 4-acetylphenyl diphenylsulfonium tetrakis (pentafluorobenzyl) borate; tris (4-thiomethoxyphenyl) sulfonium hexafluorophosphate; di (methoxysulfonylphenyl) methylsulfonium hexafluoroantimonate; di (methoxynaphthyl) methylsulfonium tetrafluoroborate; di (m ethoxynaphthyl) m ethylsulfonium

tetrakis (pentafluorobenzyl) borate; 1 di (carbomethoxyphenyl) methyl sulphonium hexafluorophosphate; (4-octyloxyphenyl) diphenylsulfonium tetrakis (3,5-bis-trifluoromethylphenyl) borate; tris (dodecylphenyl) sulfonium tetrakis (3,5-bis trifluorométhylphényiyborate; 4 ~ acétamidophényldiphénylsulfonium tetrafluoroborate; 4-acétamidophényldiphénylsulfonium tetrakis (pentafluorobenzyl) borate; hexafluorophosphate diméthylnaphthj'lsulfonium; tetrafluoroborate trifluorométhyldiphénylsulfonium; trifluorométhyldiphénylsulfonium tetrakis (pentafluorobenzyl) borate; phenylmethylbenzylsulfonium hexafluorophosphate, 10-methylphenoxathiinium hexafluorophosphate, 5-methylthianthrenium hexafluorophosphate, 10-phenyl-9,9-dimethylthioxanthenium hexafluorophosphate, 10-phenyl-9-oxothioxanthenium tetrafluoroborate, 10-phenyl-9-oxothioxanthenium tetrakis pentafluorobenzyl) borate; 5-methyl-10-oxotmanthrenium tetrafluoroborate; 5-methyl-10-oxothianthrenium tetrakis (pentafluorobenzyl) borate; (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate; 5-methyl-10,10-dioxothianthrenium hexafluorophosphate, di (dodecylphenyl) iodonium hexafluoroantimonate, di (dodecylphenyl) iodonium triflate; diphenyliodonium bisulfate, 4,4'-dichlorodiphenyliodonium bisulfate; 4,4'-dibromodiphenyliodonium bisulfate; 3,3'-dinitrodiphenyliodonium bisulfate; 4,4'-dimethyldiphenyliodonium bisulfate; 4,4'-bisuccinimidodiphenyliodonium bisulfate; 3-nitrodiphenyliodonium bisulfate; 4,4'-dimethoxydiphenyliodonium bisulfate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate; the (4-octyloxyphenyl) phenyliodonium tétj-akis (3,5-bis-trifluoromethylphenyl) borate (tolylcumyî) iodonium tetrakis (pentafluorophenyl) borate (CH ₃ C 6 H ₄₎ ₂ l- (S0 ₂ CF ₃₎ _3; preferably is (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate.

16. A method according to any one of claims 10 to 15, characterized in that in step A, said mixture comprises, in% by weight, relative to the total mass of said mixture:

17. Method according to any one of claims 10 to 16, characterized in that in step A, said mixture further comprises at least one organosilane compound comprising from 4 to 6 reactive silyl groups and / or at least one compound organosilane comprising a reactive silyl group.