Anti-reflective varnish composition, method for forming an Anti-reflective varnish, transparent substrate covered with an Anti-reflective varnish, and motor vehicle comprising such a substrate

Abstract

The invention relates to a varnish composition for forming an anti-reflective varnish, the composition containing the following ingredients: (A) a condensate of alkoxysilanes; (B) a colloidal suspension of metal oxide nanoparticles functionalised by at least one alkoxysilane; (C) an alkoxysilane; and (D) at least two organic solvents having different boiling points, the condensate of alkoxysilanes being obtained by hydrolysis and condensation of one or more trialkoxysilane(s) in an acidic aqueous-alcoholic medium. The composition can be applied by spraying, in particular via a rotating bowl and an electrostatic charge, or by immersion.

Description

DESCRIPTION Anti-reflective varnish composition, method of forming an anti-reflective varnish, transparent substrate coated with an anti-reflective varnish and motor vehicle comprising such a substrate The present invention relates to a varnish composition for producing an anti-reflective varnish, as well as to a method for forming an anti-reflective varnish on a transparent substrate. The invention also relates to a transparent substrate coated with an anti-reflective varnish, as well as to a motor vehicle comprising such a substrate. Technological background: Anti-reflective coatings for UV / Visible or Near-IR wavelength ranges find applications in many fields such as precision optics, cameras, ophthalmic and solar lenses, laser components, displays, solar power generation systems, etc. The anti-reflective function actually brings many advantages and makes it possible to optimize the operation of optical or photonic devices in which the anti-reflective treated components are integrated. They reduce parasitic reflections and the resulting damaging effects: Low contrast, visual discomfort and ghosting for ophthalmic glasses, LCD screens, OLED screens. Risk of damage to laser cavities in the case of untreated components in a laser transmission chain. Creation of ghost images for viewing optics (cameras). Decrease in efficiency and energy production for solar collectors. Anti-reflective functions are of particular interest in on-board systems equipping transport vehicles (cars, autonomous buses, aircraft, trains, etc.). In particular, for passenger vehicles, lighting and driver assistance functions are increasingly associated with complex and intelligent optical systems whose reliability and efficiency are major issues for the safety of road users. Sol-gel processes are used for the implementation of monolayer anti-reflective coatings for air / substrate interfaces, where the substrate is a material transparent to UV / Visible and near-IR wavelengths, such as mineral glasses (soda-lime, float glass, etc.), plastics such as polycarbonate (PC), polymethacrylate methyl (PMMA), polycycloolefins such as Zeonex®, etc. Sol-gel chemistry makes it possible to produce thin layers with a low refractive index, typically between 1.22 and 1.45, by formulating varnishes from suspensions of colloidal silicas, possibly functionalized. Several examples of sol-gel anti-reflection produced from colloidal nanoparticles are described. Thus, patent application LIS20130034722 describes a glass coated with a sol-gel layer formed from a formulation in alcoholic solution containing silica nanoparticles, silanes as a binder, and an acid or basic catalyst. The binder represents a mass percentage of 30 and 70% in the dry film obtained. Application methods for sol-gel anti-reflective coatings are traditionally based on coating techniques such as spin coating, dip coating, roll coating, slot die coating and, more rarely, spray coating. Single-layer anti-reflective treatments are characterized by thicknesses of around 80 to 150 nm for anti-reflective coatings in the visible range, thicknesses of around 150 nm to 250 nm for anti-reflective effects around 905 nm in the near IR and thicknesses of around 300 to 400 nm for anti-reflective effects around 1500 nm. The homogeneity of these deposits is an essential issue for many photonic applications, both for the operating efficiency of optical devices (such as LiDAR “Light Detection And Ranging” and sensors) and for aesthetic reasons.Thus, we obtain very different reflection curves between a single-layer anti-reflective coating with an index of 1.32 on PC and a thickness of 110 nm and thickness treatments with deviations of 20 nm around the target value of 110 nm (modeling for a zero angle of incidence, according to Fresnel's laws, one treated face). Similarly, in a chromaticity diagram, we can easily see the major impact on the reflected color for thickness deviations of plus or minus 20 nm versus a deviation of 12.5 nm, resulting on average in a deviation of approximately 50 nm in wavelength on the optical centering of the reflection minimum. The optical centering corresponds to the wavelength at which the reflection minimum is obtained.Similarly, the reflection level at 582 nm (optical centering of a 110 nm anti-reflective layer) will be affected by approximately 0.15 points (pt) if the deviations are of the order of 12.5 nm or less, while it will be affected by at least 0.4 pt if the deviations are of the order of 20 nm. This optical performance issue is therefore particularly acute for systems such as LiDARs that scan the environment because these devices are closed by an optical window in a material transparent to the laser wavelength, this transparent material can be polycarbonate (Makrolon® 2407 IR) or other times special glass. Dipping application techniques are not the most adapted to the need for treatment on only one of the faces of these windows, the other face usually receiving an anti-scratch treatment. It is therefore necessary to be able to propose new techniques allowing the application on an industrial scale and in a repeatable manner, with very good homogeneity, of an anti-reflective monolayer having a refractive index typically lower than 1.45. Beyond thickness homogeneity, optical quality will also be influenced by other characteristics related to the application process and the evolution of the chemistry during the application and subsequent drying / baking stage, but also with the environment in which the application is carried out. There are few descriptions of the application of anti-reflective coatings (typically <1 pm thick, or preferably <500 nm) using a spray (or aerosol) type technique, which is compatible with the optical and aesthetic quality requirements and productivity expected by certain industries such as the automotive industry. Aerosol applications of anti-reflective multilayers have been described by M. Langlet et al. (Thin Solid Films 299 (1997) 25-32). The authors used an aerosol generated using an ultrasonic nozzle, in an atmosphere saturated with ethanol. Homogeneous deposits, with thicknesses characteristic of those targeted for anti-reflective coatings, are thus obtained. But this is a complex technique, with a treatment time of a part of a few cm 2 very long, around 60 to 80 seconds, and incompatible with the covering technique, classically used in the field of industrial spray painting. Overlaying is a method for homogenizing the superposition of deposits to form a layer. It is usual to carry out a spray deposition by moving the nozzle along a line (I) in a direction (x), and then moving the nozzle in the same direction (x) in the opposite direction along a line (I') parallel to (I) and spaced by a distance dT (pitch) from (I). The nozzle passes thus generate deposits characterized by a thickness profile e, essentially in the direction (y) perpendicular to (x), e(y). In order to homogenize the thickness over the entire surface, the pitch is chosen so as to have the most homogeneous distribution of material. In other embodiments, the passes can also be made in a direction (x), then in a direction (y).The profile of a deposit using pneumatic gun technology, rotating bowl technology, or even electrostatic rotating bowl technology, is obtained by combining an operating point (liquid product flow rate, robot speed, application distance) and specific spraying parameters to atomize and convey the liquid to the substrate. The energy transmitted to the liquid comes from the air flows and, in the case of a rotating bowl, the rotation speed of the latter is added. This. energy defines sizes, speeds of droplets and their spatial distribution which can take, for example, the form of Gaussian curves. US patent 20140161980 aims to provide solutions to the problems of homogeneity in spray application of sol-gel anti-reflective coatings. The method involves the use of a mixture of solvents, in particular a solvent having, under normal temperature and pressure conditions, a boiling point above approximately 140°C or even above 175°C such as dipropylene glycol monomethyl ether (

[0020] to

[0029] ). However, under the described conditions of use of an ultrasonic nozzle, the leveling and desolvation times of each layer are at least 10 min (Examples 1 & 2), which is incompatible with mass production needs. Finally, this application mentions a target for the anti-reflective coating, in terms of RMS roughness (Roughness Squared by a Profilometer), which is not sufficiently specified to constitute technical teaching. The patent indicates that coatings, having thicknesses of the order of 200 nm or even 100 nm or less, must be characterized by RMS less than 10 nm, or even less than 1 nm. However, this characteristic is insufficient to characterize the homogeneity of an anti-reflective layer since the roughness at a micrometric scale will be largely influenced by the structure of the anti-reflective layer. On the other hand, it is mentioned in the description (

[0044] ), a standard deviation of the thickness characterized, over the entire coated surface, by optical spectroscopy, ideally less than 5, without having the methodology to give it meaning. Patent application EP3772133 presents a device for protecting a LiDAR system comprising a wall acting as a protective window from the outside, treated with anti-reflection on the inner face by a spray process. However, no mention is made of a precise method for controlling the homogeneity of the anti-reflection layer. Thickness inhomogeneities obtained during spray application can notably come from a poor definition of the impact width and the associated trajectory. These poor settings induce a disparity in the process of depositing the drops on the substrate and in their drying, resulting in a heterogeneous film with degraded optical quality. One of the most common defects with spraying is the orange peel effect. The most obvious origin is a lack of stretching or leveling of the liquid film after spraying, linked to the use of a product that is too viscous or to drying too quickly (spraying too far from the surface, too high compressed air pressure, too high ambient temperature, etc.). A well-tensioned liquid film can also deform after application due to surface tension gradients.In fact, heterogeneous spraying with a significant dispersion of droplet size will create zones. localized with a high surface tension which will attract peripheral areas with a lower surface tension. This phenomenon also occurs when fresh droplets, loaded with solvents, fall on a film which has started to evaporate. These homogeneity problems usually encountered in spray are therefore all the more impactful in the case of an anti-reflective layer and it is therefore essential to be able to control the thickness deviations compared to a target thickness defining a target optical centering. Another issue to take into account is the speed of production of an anti-reflective layer (from deposition to drying) with a view to efficient industrial production. Summary of the invention: The present invention provides a varnish composition and a method for applying this composition, making it possible to overcome the drawbacks and shortcomings of the prior art. It makes it possible in particular to treat flat or 3D anti-reflective surfaces by liquid means, on a localized surface with good homogeneity. Preferably, said varnish composition according to the invention makes it possible to overcome the drawbacks and shortcomings of the prior art whether the application method is by spraying or by immersion. Homogeneity is defined from the standard deviation o to the average of the optical centerings and the minimum reflectances over the considered wavelength range. Reflectance is defined here as the specular reflection level AOI 0° (AOI = angle of incidence) of the anti-reflective treated surface R m in % and the optical centering is the wavelength  o(nm) at which the minimum reflectance is obtained. An OR is thus defined as the standard deviation on the reflectance level and o% as the standard deviation on the optical centering. In the case of the interference and transparent anti-reflective layers of the invention, the thickness is determined from the measurement of the reflectivity of the anti-reflective surface using a UV / Visible / Near IR spectrometer and the modeling of the anti-reflective layer / substrate stack according to an optical model drawn in particular from Fresnel's laws which highlight that the spectral reflection obtained from the surface of a transparent substrate covered with a transparent layer (whose absorption at the wavelength considered is negligible) varies periodically as a function of e / X, where X is the wavelength of the light. A determination of these thicknesses can be obtained with a Filmetrics device of the F20 or F-10AR or F10-HC type.The approach and the models in reference are for example explained in the document "Thin Film Measurement - Filmetrics" available from the company Filmetrics Inc. (USA). Thus, to a homogeneity. also corresponds to a homogeneity in thickness e . The homogeneity targeted in the invention is o% < 60 nm, better < 50 nm and typically corresponding to homogeneities o e <12.5 nm, better at <10 nm. These homogeneities are obtained, according to the invention, with a very rapid processing time (typically about at least 1 m 2 approximately every 30 seconds), and very good optical quality. A methodology for determining homogeneity c A e to RIt consists of measuring the reflectance and the optical centering at 25 points, typically on a representative anti-reflective treated surface of 25 cm x 15 cm (with several spray coating passes). The optical quality will be notably attested by an optical diffusion in the visible range which is characterized according to the ASTM 1003 standard (illuminant C or A) using a Byk Gardner Haze Gard I type apparatus. Thus, the Δhaze in %, the difference between the haze of the substrate coated with the anti-reflective layer and the haze due to the substrate alone, is considered for the optical applications of the invention, and substrates having a haze % in the visible range less than or equal to 0.35% are generally preferred. The optical quality will also be characterized by the value of the minimum reflectance and / or the transmission gain in the UV / Visible / NIR range around the sought optical centering wavelength (compared to the untreated substrate). A first subject of the invention is therefore a varnish composition containing in particular the following ingredients: (A) an alkoxysilane condensate, (B) a colloidal suspension of metal oxide nanoparticles functionalized with at least one alkoxysilane, (C) an alkoxysilane or a solution containing an alkoxysilane, and (D) at least two organic solvents with different boiling points, or a mixture comprising two organic solvents with different boiling points. The composition is of the hybrid sol-gel type (inorganic-organic) in a hydro-alcoholic medium. A second subject of the invention is a method for applying this varnish composition to the surface of a substrate, generally transparent, which may be flat or 3D, and the formation of a continuous or discontinuous layer of varnish on the surface of this substrate. The substrate may be made of plastic or glass. It is in particular transparent in the UV / Visible and near infrared (N IR “Near InfraRed” or SWIR “Short-Wave InfraRed”) ranges. This application method may in particular use electrostatic deposition, preferably using an electrostatic rotating bowl. In one embodiment, a sprayer equipped with a rotating bowl is used for the spray. This rotating bowl may have a circular edge with a diameter of between approximately 35 and approximately 65 mm. The rotating bowl is driven in rotation by means of a turbine. The turbine may operate over a rotation speed range of between approximately 20,000 and approximately 80,000 rpm. The sprayer may be supplied from a varnish composition reservoir, through an adjustable feed pump and making it possible to supply the sprayer with a flow rate of varnish composition which is adjustable, for example between approximately 20 and approximately 150 cc / min. Other applicable characteristics, which may be combined with these, are described later, in particular in connection with the figures. This method and this composition allow in particular the production of an anti-reflective treatment, preferably with a thickness of 70 to 500 nm, on a localized surface. Advantageously, this method makes it possible to produce an anti-reflective treatment or coating, preferably by spray, meeting at least two, at least three, at least four, at least five or at least six of the following criteria: Achieving anti-reflective treatment with homogeneity less than or equal to 65 nm, preferably 60 nm, in particular 50 nm; and / or A treatment-induced AHaze of less than or equal to 0.5%, 0.4% or 0.3%, in particular measured according to ASTM 1003 (illuminant C or A), in particular using a Byk Gardner device of type Haze Gard I; and / or A refractive index between 1.22 and 1.45, preferably 1.22 and 1.44; and / or A minimum reflectance over the wavelength range considered AGI 0° less than or equal to 3%, 2% or 1.7%, preferably less than or equal to 1.5%, better still less than or equal to 1.2%, even better still less than or equal to 0.9% at the minimum reflection; and / or An OR homogeneity less than or equal to 0.20%, preferably less than or equal to 0.15%, preferably less than or equal to 0.1%, in particular 0.07%; and / or Very short processing time, typically 1m 2 every 30s. The level of minimum reflectance, however, remains linked to the values ​​of the refractive indices of the substrate and the deposited anti-reflective layer. Generally speaking, the means of the lowest reflectance will be sought and of a value very close for a spray application to what it is in dipping-removal on one side of a substrate (the opposite side being protected so as not to apply treatment). The droplet coalescence mechanism is inherent in any spray application process. Mastering it is essential to hope to form a uniform film. Among the parameters that are difficult to control, the inventors have identified the evaporation rate of the droplets formed and the polymerization process (or sol-gel transition). In a preferred embodiment, the method uses an electrostatic rotating bowl applicator. This may notably be composed mainly of: a bowl rotating at an adjustable rotation speed, an air injection skirt for shaping the cloud of droplets, with a controlled flow rate, a High Voltage unit whose voltage and current consumption are controlled. The bowl, due to its shape and rotation speed, allows the liquid film to be atomized into a cloud of droplets, the size distribution of which is controlled. The air of the skirt participates in transporting the cloud of droplets towards its target while respecting an impact width on the substrate. This air injection is obtained via a combination of several vents (angles, orientation, diameter of the injection holes, ...) in order to obtain an aerodynamic balance associated with the atomization of the bowl. The High Voltage unit enables the droplets created at the outlet of the bowl to be electrically charged. The advantage of the electrostatic principle, applied to the sprayed cloud, is reflected in a better homogeneity of the cloud and a better deposition efficiency. The combined use of these elements, especially in combination with the characteristics of the anti-reflective varnish composition of the invention, allows, with a good configuration of the control parameters, to ensure that the deposition of the sol-gel film corresponds well to the required quality after drying. A third subject of the invention relates to an anti-reflective coating of the sol-gel type (or obtained by a sol-gel process), capable of being obtained from the varnish composition according to the invention, preferably deposited by implementing the process of the invention. The term "coating" refers to the layer or "coating" obtained after at least drying and hardening of the varnish composition, and notably involves polymerization. The varnish can be described as an inorganic-organic hybrid glassy material or polymer. The invention also relates to a substrate, which may be flat or 3D, in particular a substrate transparent to visible or N IR wavelengths, coated over its entire surface or only part of it, with such an anti-reflective varnish. This substrate may in particular be made of plastic (PC, PMMA, COP, PET, PMMI, etc.), glass, or sapphire. In particular, the choice of the varnish composition and its method of deposition, including a spraying phase under conditions avoiding drying of the varnish composition droplets before reaching the receiving substrate, followed by a phase in which the composition of the wet deposit freezes on the surface of the substrate, then finally the actual baking or drying phase, together make it possible to solve the multiple technical problem mentioned above. In another aspect, the invention relates to a method of forming an anti-reflective varnish on a transparent substrate, comprising spraying, preferably by means of an electrostatically charged rotating bowl sprayer, a varnish composition as mentioned above, and then drying the composition to form the varnish. According to another aspect, the invention relates to a transparent substrate coated on one side in whole or in part with a dried anti-reflective varnish obtained by the process as mentioned above or with the dried varnish resulting from the composition mentioned above. In one aspect, this coated transparent substrate constitutes a protective device for an automotive front or rear headlight, a LiDAR, a camera. It can also be an optical lens of an automotive front and rear headlight device, a LiDAR, a camera. In one aspect, the substrate is polycarbonate or polymethyl methacrylate (PMMA) or glass, especially float glass. According to another aspect, the invention relates to a motor vehicle comprising at least one substrate as described herein. Introduction of figures: The present invention will now be described in more detail with the aid of exemplary embodiments referring to the Figures. Figure 1 schematically represents a method, in accordance with the invention, of applying the varnish composition of the invention to a substrate; Figure 2 schematically represents, on two inserts A) and B), an impact disc and layers applied to the substrate, due to the implementation of the method of figure 1. Detailed description: The varnish composition comprises (A) a condensate (or hydrolyzate-condensate, the two names being used interchangeably in the present application) of alkoxysilanes, (B) a colloidal suspension of metal oxide nanoparticles functionalized by an alkoxysilane, (C) an alkoxysilane or a solution of at least one alkoxysilane, and (D) at least two organic solvents of different boiling points, or a mixture of at least two organic solvents of different boiling points. According to a characteristic of the invention, the varnish composition is such that obtained by the addition of the alkoxysilane condensate (A) to the other components. In other words, the condensate (A) present in the composition has been condensed prior to its incorporation. As will be explained later, it has at its incorporation and in the varnish composition before the formation of the varnish, a condensation rate within a certain range, but it is not 100% condensed. In addition to a controlled degree of condensation, its pre-condensation is carried out on the basis of the mixture of its constituent alkoxysilanes, in this sense also it is controlled. The condensate is in particular essentially constituted or constituted by the condensation of the alkoxysilanes entering into its composition before incorporation into the varnish composition. (A) Alkoxysilane condensate: The alkoxysilane condensate (A) can in particular be obtained from a trialkoxysilane (1) or from several different trialkoxysilanes (1), such as those which will be described in more detail below. It can also be obtained from one or more of these trialkoxysilanes (1), and one or more other silanes, in particular a tetraalkoxysilane (2) or several different tetraalkoxysilanes (2), and / or a dialkoxysilane (3) or several dialkoxysilanes (3), and / or a bisilane (4) or several different bisilanes (4). Such suitable silanes (1), (2), (3), (4) will be described in more detail below. The condensate (or more precisely the hydrolysate-condensate due to its method of preparation) of alkoxysilanes (A) can be obtained by hydrolysis-condensation in an acidic medium, in particular hydroalcoholic, of the species retained, and therefore comprising at least one or more trialkoxysilane(s) (1). The trialkoxysilane (1) may in particular be of formula R 1 -If(OR 2 )a where: -GOLD 2 is a hydrolyzable group, in particular an alkoxyl radical having in particular from 1 to 4 carbon atoms, such as a methoxy, ethoxy, propoxy, iso-propoxy, or butoxy group, R 1 is an organic radical chosen from H; a linear or branched organic radical of alkyl type (in particular from 1 to 30 C, preferably from 1 to 12 C), cycloalkyl (in particular from 5 to 7 C), alkenyl (in particular from 1 to 30 C, preferably from 1 to 12 C), and optionally comprising heteroatoms such as O, S, N, this radical possibly being: an oxypropyl or thiopropyl group, for example methacryloyloxypropyl or glycidoxypropyl; allyl (H2C=CH-CH2-); vinyl (-Ch ChL); aromatic or polyaromatic cycle such as for example phenyl, bi-phenyl, naphthyl or phenanthrene, optionally substituted; these radicals possibly being substituted or not. The trialkoxysilane(s) (1) may in particular be chosen from: triethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, propyl trimethoxysilane, propyltriethoxysilane, butyltriethoxysilane, methyldiethoxyvinylsilane, phenyltrimethoxysilane, phenantrene-9-triethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, acryloxypropyltrimethoxysilane, allyltrimethoxysilane, epoxycyclohexylethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, , 1 H, 1 H, 2H, 2H- perfluorodecyltriethoxysilane, nonafluoro hexyltriethoxysilane, trimethoxy (3,3,3-trifluoropropyl)silane, 3-chloropropyltriethoxysilane, chloromethyltriethoxysilane. A combination or mixture of two or more of these compounds may be used. As trialkoxysilanes, the following are preferably used: methyltriethoxysilane, methyltrimethoxysilane, propyltriethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, or a combination or mixture of at least two of these compounds. The hydrolyzate-condensate (A) can be obtained, in a preferred embodiment, by the hydrolysis-condensation in an acid medium of at least one trialkoxysilane (1) and at least one alkoxysilane of tetraalkoxysilane type (2). The tetraalkoxysilane (2) may in particular be chosen from tetramethoxysilane and tetraethoxysilane. The hydrolyzate-condensate (A) can be obtained, in another preferred embodiment, by the hydrolysis-condensation in an acid medium of at least one trialkoxysilane (1) and at least one alkoxysilane of dialkoxysilane type (3). Dialkoxysilane (3) can be of formula R 3 2-If(OR 2)2 where -OR 2 is a hydrolyzable group, in particular an alkoxyl radical having from 1 to 4 carbon atoms, such as a methoxy, ethoxy, propoxy, iso-propoxy, butoxy group; R 3 is an organic radical chosen from H; a linear or branched organic radical of the alkyl type (in particular from 1 to 30 C, preferably from 1 to 12 C), cycloalkyl (in particular from 5 to 7 C), alkenyl (in particular from 1 to 30 C, preferably from 1 to 12 C), and optionally comprising heteroatoms such as O, S, N, this radical possibly being: an oxypropyl or thiopropyl group, for example methacryloyloxypropyl or glycidoxypropyl; allyl; vinyl; aromatic or polyaromatic cycle, such as for example phenyl, bi-phenyl, naphthyl or phenanthrene, optionally substituted; these radicals may be substituted or not. The dialkoxysilane(s) may in particular be chosen from: dimethyldiethoxysilane, dimethyldimethoxysilane, 3-(glycidoxypropyl)methyldiethoxysilane, diisobutyldiethoxysilane, dodecylmethyldiethoxysilane, vinylmethyldiethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-chloropropyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, chloromethylmethyldiethoxysilane, (2-diethylphosphatoethyl)methyldiethoxysilane, (mercaptomethyl)methyldiethoxysilane, (3-(N-ethylamino)isobutyl)methyldiethoxysilane, (3-isocyanatopropylmethyldiethoxysilane), n-(aminoethyl)3-(aminopropylmethyldiethoxysilane), diethyldiethoxysilane, (methacryloxymethyl)methyldiethoxysilane, n-octadecylmethyldiethoxysilane, n- octylmethyldiethoxysilane, phenylmethyldiethoxysilane, methyldiethoxysilane, (3-acryloxypropyl)methyldiethoxysilane, methacryloxypropylmethyldiethoxysilane, diphenyldiethoxysilane, (3,3-dimethylbutyl)methyldiethoxysilane, phenyldiethoxysilane, vinylphenyldiethoxysilane, bis(pentafluorophenyl)dimethoxysilane, (3- glycidoxypropyl)methyldimethoxysilane, diisobutyldimethoxysilane, diisopropyldimethoxysilane, vinylmethyldimethoxysilane, (o- methacryloxyethoxy)carbamoylpropylmethyldimethoxysilane, phenylmethyldimethoxysilane, 3-chloropropylmethyldimethoxysilane, n-methylaminopropylmethyldimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, di-n-octyldimethoxysilane, (methacryloxymethyl)methyldimethoxysilane, isobutylmethyldimethoxysilane, di-n-butyldimethoxysilane, allylmethyldimethoxysilane, diphenyldimethoxysilane, vinylmethyldimethoxysilane, bis(pentafluorophenyl)dimethoxysilane, methyldimethoxysilane, cyclohexylmethyldimethoxysilane, 1,2-bis(trimethoxysilyl)ethane. A combination or mixture of two or more of these compounds may be used. As dialkoxysilanes, the following are preferably used: dimethyldiethoxysilane, dimethyldimethoxysilane, 3-(glycidoxypropyl)methyldiethoxysilane, diisobutyldiethoxysilane, vinylmethyldiethoxysilane, diethyldiethoxysilane, (methacryloxymethyl)methyldiethoxysilane, phenylmethyldiethoxysilane, methyldiethoxysilane, vinylmethyldimethoxysilane, diphenyldimethoxysilane, 1,2-bis(trimethoxysilyl)ethane. The hydrolyzate-condensate (A) can be obtained, in another preferred embodiment, by the hydrolysis-condensation in an acid medium of at least one trialkoxysilane (1) and one bisilane (4). Bisilane (4) can respond to the formula: (OR 5 )3Si — Y — Si(OR 6 )3 in which OR 5 and -OR 6 are hydrolyzable groups, identical or different, preferably identical, in particular chosen from an alkoxyl radical having from 1 to 4 carbon atoms, such as methoxy, ethoxy, propoxy, iso-propoxy, butoxy; Y is a spacer skeleton, namely an unsubstituted or substituted aliphatic group having from 1 to 12 carbon atoms, such as alkylene, arylene, — O-alkylene-O —; — O-arylene-O —; alkylene-O-alkylene, arylene-O-arylene; alkylene-Z 1 C(=O)Z 2 -alkylene, arylene-Z 1 C(=O)Z 2 -arylene, — O-alkylene- Z 1 C(=0)Z 2 -alkylene-0 — ; — 0-arylene-Z 1 C(=0)Z 2 -arylene-0 — , alkylene-SS-alkylene, alkylene-SSSS-alkylene, and where Z 1 and Z 2are independently a direct bond or -O-, or aromatic, such as for example phenyl, bi-phenyl, naphthyl or phenanthrene, optionally substituted. Examples of bisilanes include, but are not limited to, 1,2-bis(trimethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethane, 1-(dimethoxymethylsilyl)-1-(trimethoxysilyl)methane, 1-(diethoxymethylsilyl)-1-(triethoxysilyl)methane, 1-(dimethoxymethylsilyl)-2- (trimethoxysilyl)ethane, 1-(diethoxymethylsilyl)-2-(triethoxysilyl)ethane, bis(dimethoxymethylsilyl)methane, bis(diethoxymethylsilyl)methane, 1,2-bis(dimethoxymethylsilyl)ethane, 1,2-bis(diethoxymethylsilyl)ethane, 1,2-bis(trimethoxysilyl)benzene, 1,2-bis(triethoxysilyl)benzene, 1,3-bis(trimethoxysilyl)benzene, 1,3-bis(triethoxysilyl)benzene, 1,4-bis(trimethoxysilyl)benzene, 1,4-bis(triethoxysilyl)benzene, 4,4'-Bis(triethoxysilyl)-1,1'-biphenyl; 1,4- Bis(triethoxysilyl)benzene; 1, 3- Bis(triethoxysilyl) benzene, bis[3- (triethoxysilyl)propyl]tetrasulfide, bis[3-(triethoxysilyl)propylsulfide A combination or mixture of two or more of these compounds may be used. As bisilanes, the following are preferably used: 1,2-bis(trimethoxysilyl)ethane, 1,2-bis(dimethoxymethylsilyl)ethane, 1,2-bis(trimethoxysilyl)benzene, 4,4'-Bis(triethoxysilyl)-1,1'-biphenyl; 1,3-Bis(triethoxysilyl)benzene, bis[3-(triethoxysilyl)propyl]tetrasulfide, bis[3-(triethoxysilyl)propylsulfide. A combination or mixture of at least two of these compounds can be used. The following silane combinations are preferably used: methyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, dimethyldiethoxysilane methyltrimethoxysilane, diisobutyldiethoxysilane methyltriethoxysilane, tetraethoxysilane, 3-(glycidoxypropyl)methyldiethoxysilane methyltrimethoxysilane, tetraethoxysilane, phenyltrialkoxysilane methyltriethoxysilane, methacryloxypropyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, 3-(glycidoxypropyl)methyldiethoxysilane, dimethyldiethoxysilane 1,2-bis(trimethoxysilyl)ethane, methyltriethoxysilane, 3-glycidoxy propyltrimethoxysilane, dimethyldiethoxysilane methyltrimethoxysilane, methacryloxypropyltrimethoxysilane, dimethyldiethoxysilane methyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, dimethyldiethoxysilane, methacryloxypropyltrimethoxysilane tetraalkoxysilane, phenyltrimethoxysilane, dimethyldiethoxysilane tetraethoxysilane, phenyltrimethoxysilane,dimethyldiethoxysilane or 3-glycidoxypropyltrimethoxysilane, tetraethoxysilane., For the preparation of the hydrolyzate-condensate comprising several types of silanes, the silane(s) of type (1) are mixed with at least one silane of type (2), (3) or (4) in a hydro-alcoholic medium in a molar ratio [(2) or (3) or (4)] / (1) of less than about 50%, preferably between about 0.5% and about 50%, preferably between about 1 and about 20%, preferably between about 2 and about 15%. In the case of mixing 2 or 3 of the categories of silanes (2), (3), (4), these molar ratios are expressed as [mixture] / (1) of less than about 50%, preferably between about 0.5% and about 50%, preferably between about 1 and about 20%, preferably between about 2 and about 15%. The varnish composition for forming an anti-reflective varnish therefore more particularly relates to a composition containing the following ingredients: (A) an alkoxysilane condensate, (B) a colloidal suspension of metal oxide nanoparticles functionalized by at least one alkoxysilane, (C) an alkoxysilane, and (D) at least two organic solvents with different boiling points, the alkoxysilane condensate (A) being obtained by hydrolysis and condensation, in an acidic hydroalcoholic medium, of at least one or more trialkoxysilane(s) (1) and, optionally, in addition, of at least one other silane chosen from tetraalkoxysilanes (2), dialkoxysilanes (3), bi-silanes (4) or one of their mixtures, the molar ratio [(2) and / or (3) and / or (4)] / (1) being less than 50%. The hydro-alcoholic medium is composed of a mixture comprising or consisting of water, in particular distilled water, and alcohol. The alcohol may be chosen in particular from: methanol, ethanol, 1-propanol (propan-1-ol), 2-propanol (propan-2-ol), 1-butanol, isobutanol, 1-hexanol, 1-methoxy-2-propanol, isopropoxy-ethanol or a mixture of at least two of these alcohols. The mass proportion of alcohol relative to the total mixture of hydro-alcoholic medium is from 0.001 to approximately 50%, preferably between 0.01 and approximately 25%. The alcohol may be added to the reaction medium during the synthesis of the hydrolyzate-condensate and / or be produced by the hydrolysis-condensation reaction. The hydrolysis-condensation reaction is typically carried out in an acidic medium, at a pH between 1 and 7, preferably between 1.5 and 6, preferably between 2 and 5.5. The acidity acts as acid catalysis for the hydrolysis-condensation reaction. The hydro-alcoholic medium then additionally comprises an acid, preferably a mineral acid, such as for example HCl, HNO3, H2SO4, H3PO4, or an organic acid, such as for example acetic acid, propanoic acid, butanoic acid, citric acid, oxalic acid, lactic acid, maleic acid, fumaric acid, itaconic acid; the medium may also comprise a mixture of at least two of these acids. The quantity of acid is adapted according to its nature to obtain the acidified hydro-alcoholic medium having a pH in the indicated range. Acid catalysis is preferably implemented by adding to the reaction mixture (silanes and hydro-alcoholic medium) an aqueous acid solution with the appropriate acid concentration to obtain the pH retained for the complete solution; in this case the quantity of water added to the medium will preferably be reduced by the quantity of aqueous acid solution; in the case of the use of strong acid, the molar ratio [H+] / [silane] is in particular between 10' 7 and 10' 2 , preferably between 10' 5 and 10' 2 ; in the case of the use of weak organic acid, the acid catalysis is the ratio [acid] / [silane] will be in particular between 0.1 and 0.5, preferably between 0.25 and 0.45. The hydrolysis-condensation reaction is preferably carried out by mixing the selected silanes (1) to (4) as well as the alcohol(s), water (especially distilled water) and the acid. The mixture is stirred by usual means allowing good homogenization. The hydrolyzate-condensate according to the invention can be characterized in particular by its condensation rate after concentration. A high condensation rate is targeted. The condensation rate Te is typically greater than or equal to approximately 60%, preferably greater than or equal to approximately 70 or 75%. Te is in particular between 60 and 97.5%, in particular between 65 and 95%, in particular between 70 and 92%, more particularly between 75 and 90%, preferably between 77.5% and 87.5%. Condensation leads to the formation of polysiloxanes. NMR 29Si is a technique that allows quantification of the proportion of each type of unit in the polysiloxane skeleton(s) thus obtained, in particular the Ti, T2 and T3 type units associated with different types of condensation state. The nomenclatures of the different condensation units in a sol-gel skeleton are described in the thesis "Organosilanes / Precipitation Silica Interaction - From the Hydro-Alcoholic to the Aqueous Medium" by Sophie de Monredon-Senani (Pierre and Marie Curie University - Paris VI, 2004. French, fftel-00012113f, page 59). The most condensed units are of type T3. The condensation rate T c can be defined from the relative proportion of each unit, as follows: In the case of the contribution of units of type Q n (n from 1 to 4), we will count each contribution by a term of the type: Similarly in the case of the use of di-alkoxysilane with D-type unitsn (n from 1 to 2), we will count each contribution by a term of the type: The duration, temperature and pressure during the condensation reaction make it possible to obtain a high condensation rate. Preferably, the reaction can be carried out over a period of about 4 hours to about 48 hours, for a temperature between room temperature (between about 20 and about 25°C) and about 100°C, preferably between about 15°C and about 100°C, better still between about 25°C and about 90°C, preferably between about 50°C and about 85°C and a pressure between about 200 mbar and about 2 bar, preferably between about 500 mbar and about 1.5 bar, typically about 1 bar. The hydrolyzate-condensate or polysiloxane resin thus obtained is then isolated and / or a modification / change of solvent can be carried out to prepare an anti-reflective formulation according to the invention. To isolate the resin, the reaction medium obtained can be extracted in a liquid / liquid biphasic extraction method according to techniques known to those skilled in the art. This can be done, for example, by diluting the reaction mixture in an aqueous medium, followed by extraction, generally in several stages, using a solvent immiscible with water, such as diethyl ether, ethyl acetate, butyl acetate, or chloroform. The organic phases containing the polysiloxanes, resulting from the successive extractions, are then combined and optionally concentrated, in particular under reduced pressure. To isolate the resin, it can also be done by modifying or changing the solvent. A solvent transfer is carried out so as to disperse the hydrolyzate-condensate resin. The resin obtained after reaction of the silanes in an alcoholic medium can be extracted with a solvent immiscible with water, such as diethyl ether, ethyl acetate, butyl acetate, or chloroform. The extracted medium is then made up with a volume of a solvent having a boiling point substantially higher than that of the solvent used for the extraction, the volume being advantageously chosen to be equal to or less than the total volume of organic solvent + water added at the start of the hydrolysis. The medium is preferably concentrated, in particular under reduced pressure, so as to obtain a solution of hydrolyzate-condensate in the transfer solvent (majority transfer solvent).Said solvent may be chosen from: 2-isopropoxyethanol (CAS 109-59-1) with a boiling point of 143°C, propylene glycol methyl ether acetate (PGMEA) with a boiling point of 146.4°C, 2-butoxyethanol (CAS 111-76-2) with a boiling point of 171°C, di(propylene glycol) dimethyl ether (CAS 111109-77-4) with a boiling point of 175°C, ethyl-2-hexanol-1 (CAS 104-76-7) with a boiling point of 186°C. Using the above two approaches, a concentrated organic phase or solution of resin is obtained, which has a high viscosity. The resin is present in the form of a macromolecule or an oligomer in a little solvent, after an incomplete reaction or gelation of the silanes. The resin is further specified by its Ti, T2 and T3 units and by NMR. 29 Yes, and therefore by his Te. The organic solution containing the hydrolyzate-condensate obtained with these two methods can be characterized in dry extract in order to then allow the preparation of an anti-reflective formulation. The dry extract of the alkoxysilane condensate (A) in the concentrated phase or solution is in particular between approximately 65% ​​and approximately 90%, more specifically between 80 and 90%, preferably between 82.5% and 87.5%. This dry extract (SE) % by weight is in particular measured as follows. At least 2 g of the organic solution containing the hydrolyzate-condensate - designated miiq) are taken into an aluminum cup. The cup is placed in a thermostatically controlled oven at 180°C for 30 minutes. The mass of the cup is weighed empty (mvide), then after pouring the solution to be characterized (mii q ), and again after steaming (dry). The value of the dry extract is given by the formula: ES % = ((m S arrow -m V ide) / mii q )x100. The same method of measuring ES is used to measure the dry extract of the colloidal solution or suspension (B) or of the varnish composition. In this case, the temperature of the thermostatically controlled oven is set at 120°C. The structure of the obtained sol-gel / polysiloxane resin is typically characterized by NMR 29 Yes. The spectrogram obtained shows in particular peaks associated with units of type Ti, T2 and T3, characteristic of condensation units of trialkoxysilane or of a mixture of trialkoxysilanes as defined previously. The characterization methods are described for example in the thesis of Eveny Borovin (“NMR Characterization of solgel derived hybrid nanomaterials: Insight on organic-inorganic interfaces, pages 80 & 93, Published in Trento (Italy) - by University of Trento). The spectrum may also exhibit peaks characteristic of units of type D1 and D2 resulting from the condensation of a dialkoxysilane or a mixture of dialkoxysilanes; finally, it may comprise units of types Qi, Q2, Q3 and C characteristic of the condensation of a tetraalkoxysilane or a mixture of tetraalkoxysilanes as defined above. Under suitable experimental conditions allowing a quantitative measurement of the different units, it is easy to quantify the relative proportions of each type of unit. The sol-gel resin of the invention will in particular be characterized by a percentage of T2+T3 at least equal to 45%, preferably at least equal to 70%, preferably greater than 85%. The sum of the units D1+D2 will be at least equal to 0.5%, preferably at least equal to 2.5%, preferably at least equal to 5%. The Qi+Ch+Ch+C units will preferably be less than 5%, preferably less than 2.5%, preferably less than 1%. Peaks assigned to T1 / T2 / T3 type units are preferably, without limitation, trialkoxysilanes substituted with a methyl-, ethyl-, propyl-, isobutyl-, methacryloxypropyl-, glycidoxypropyl-, phenyl-type group. Peaks assigned to D1 / D2 type units are preferably, without limitation, di-alkoxysilanes substituted with a dimethyl-, diethyl-, diphenyl, di-isobutyl type group. (B) Colloidal suspension or dispersion of functionalized metal oxide nanoparticles: This colloidal suspension (B) is in particular formed, or prepared from, colloidal suspensions of metal oxides. These suspensions can be of different types, chosen from: aqueous suspensions; suspensions in an organic solvent; suspensions in mixtures of solvents (aqueous and organic, or only organic); suspensions in reactive diluents. It can be a mixture of at least two of these different types, forming a stable suspension for the concentration range desired mass, which can be determined by particle size measurements using a Dynamic Light Scattering method, i.e. with invariant particle size characteristics (typically size changes of less than 10%). In this presentation, the terms suspension and dispersion will be used interchangeably. Colloidal suspensions of metal oxides may typically be suspensions of silica or hybrid silica. Hybrid silica is understood to mean in particular SiC>2 carrying one or more organic components, in particular one or more organosilanes, preferably linked by covalent bonding. This includes in particular the functionalized silicas cited below. The mass concentrations or dry extract may be between approximately 1.5 and approximately 65%, in particular between approximately 3 and approximately 50%, preferably between approximately 5% and approximately 45%, more preferably between approximately 10 or 15 and approximately 45%, or between approximately 10 or 15 and approximately 40%, expressed relative to the colloidal suspension. The metal oxide nanoparticles used for implementing the invention will preferably have suspended particle sizes of between approximately 2 nm and approximately 250 nm, in particular between approximately 5 nm and approximately 150 nm, in particular between approximately 8 and approximately 100 nm, more particularly between approximately 10 and approximately 100 nm, preferably between approximately 12 and approximately 80 nm. These particle sizes can be measured according to various techniques known to those skilled in the art. For direct measurement on suspended particles, suitable methods are dynamic light scattering techniques that can be implemented on VASCO equipment marketed by CORDOUAN or equipment from the Zetasizer range of MALVERN (Zetasizer pro device, for example). Examples of implementation of the methods are described in Glass Physics and Chemistry, 2016, Vol. 42, No. 4, pp. 414-420 (page 416), NA Shabanova et al. For measurement on solid-state particles after deposition, the methods described in RSC Adv., 2017, 7, 54986-54994 (page 54988), Ji Hu et al. The solvents or mixtures of solvents, in particular water or organic solvent(s), used for the dispersion of the colloids will be chosen, in addition to their ability to stabilize the colloidal suspension, so as to be able to evaporate easily at atmospheric pressure and room temperature, typically between approximately 18 and approximately 30°C, after application of the final varnish to a surface, to form a dry film, preferably in less than approximately 3 minutes, in particular in a period of between 10 and 300s, preferably between 30s and 200s, preferably between 50s and 180s. Alternatively, evaporation may be forced by placing the coated surface in a heated atmosphere using an oven or stove, at a temperature and duration compatible with the coated material or substrate (typically approximately 190°C for a PET material for a time of the order of a few minutes, a temperature of approximately 120°C or less for a polycarbonate material for a typical duration of approximately 10 minutes to approximately 240 minutes, a temperature of approximately 80°C or less for a PMMA material for a typical duration of approximately 5 minutes to approximately 480 minutes). The solvents or dispersion media are preferably chosen from: water, 1,4-dioxane, acetone, acetonitrile, cyclohexane, cyclohexanone, cyclopentanone, dichloromethane, diethyl acetate, diethyl ketone, dimethyl carbonate, dimethylformamide, dimethylsulfoxide, ethanol, methanol, ethyl acetate, m-cresol, substituted mono- and di-alkyl glycols, N,N-dimethylacetamide, 1,2-propanediol, 1-pentanol, 1-propanol, 2-hexanone, 2-methoxyethanol, 2-methyl-2-propanol, 1-methoxy-2-propanol, 2-octanone, 2-propanol (isopropanol or propan-2-ol), 3-pentanone, 4-methyl-2-pentanone, methyl acetate, methyl acetoacetate, methyl ethyl ketone, methyl propyl ketone, n-methylpyrrolidone-2, n-pentyl acetate, phenol, tetrahydrofuran, toluene, xylene. Preferably, the following are used: water, 1,4-dioxane, dimethylsulfoxide, ethanol, methanol, ethyl acetate, 1,2-propanediol, 1-propanol, 2-methoxyethanol, 2-methyl-2-propanol, 1-methoxy-2-propanol, 2-propanol, 4-methyl-2-pentanone, methyl ethyl ketone, methyl propyl ketone, n-methylpyrrolidone-2, or tetrahydrofuran. The dispersion medium may also comprise, or be composed of, a reactive solvent (or reactive diluent) or monomer comprising at least one polymerizable group, thermally or UV-conductive, in particular of the vinyl unsaturation type. Examples of monomers having a polymerizable group: N-vinyl pyrrolidone, N-vinyl caprolactam, vinyl imidazole, vinyl pyridine; isobornyl (meth) acrylate, bornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 4-butylcyclohexyl (meth) acrylate, acryloyl morpholine, methacrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, caprolactone acrylate,isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, tridecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol (meth) acrylate, ethoxyethyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, isobutoxymethyl (meth) acrylamide, N,N-dimethyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, hydroxybutyl vinyl ether, lauryl vinyl ether, 2-ethylhexyl vinyl ether; and compounds of formula (I) CH2=C(R 6 )-COO(R7 O) m R 8 , where R 6 is a hydrogen atom or a methyl group; R 7 is an alkylene group containing from 2 to 8, preferably from 2 to 5, carbon atoms; m is an integer from 0 to 12, and preferably from 1 to 8; R 8 is a hydrogen atom or an alkyl group containing from 1 to 12, preferably from 1 to 9, carbon atoms; or R 8 is a tetrahydrofuran group with 4 to 6 carbon atoms, optionally substituted with alkyl groups having 1 or 2 carbon atoms; or R 8 is an aromatic group, of the alkylphenyl type, optionally substituted with alkyl groups having from 1 to 12 carbon atoms, preferably alkyl groups of 1 to 8 carbon atoms. Preferably, the following are used: N-vinyl pyrrolidone, N-vinyl caprolactam, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, methacrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate, caprolactone acrylate, octyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, or 2-ethylhexyl vinyl ether. The dispersion medium may also comprise, or be composed of, a mixture of components containing reactive diluents or monomers having more than one polymerizable group, thermally or UV, of the vinyl unsaturation type.Examples of reactive monomers and diluents comprising several polymerizable groups, such as vinyl unsaturations, are for example: trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polybutanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, glycerol tri(meth)acrylate, phosphoric acid mono- or di(meth)acrylates, C7-C20 alkyl di(meth)acrylates, trimethylolpropanetrioxyethyl (meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxy pentacrylate, dipentaerythritol hexacrylate, and alkoxylated versions of the preceding examples, preferably ethoxyl or propoxyl as well as. di(meth)acrylates of diols derived from the adduct of ethylene oxide or propylene oxide chains with bisphenol A or bisphenol F groups, epoxy (meth)acrylate corresponding to an adduct of bisphenol A with diglycidyl ether, polyoxyalkylated bisphenol A diacrylate, hydroxyethyl acrylate adduct, isophorone diisocyanate and hydroxyethyl acrylate. Preferably, the following are used: trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, or pentaerythritol tetra(meth)acrylate. Examples of colloidal suspensions include suspensions supplied, for example, by Nissan Chemical, which markets suspensions or dispersions of silica nanoparticles under the brand name ORGANOSILICASOL®. Commercial grades useful for the invention include, for example: - MA-ST, MA-ST-M, MA-ST-L having particle sizes of 12 to 45 nm dispersed in methanol; - IPS-ST, IPA-ST-L, IPS-ST-ZL having particle sizes of 12 to 80 nm dispersed in isopropyl alcohol; and - PGM-ST, PGM-ST-ZL, PGM-ST-UP with particle size of 12 to 80 nm in propylene glycol methyl ether. It may also be suspensions or dispersions in ketone-type solvents, for example, such as MEK-ST40, MEK-ST-L, MEK-ST-ZL or MEK-ST-UP having a particle size of 12 to 80 nm, or dispersions in acetates such as EAC-ST, EAC-ST-ZL having particle sizes of 12 to 80 nm, or dispersions in toluene such as TOL-ST with a particle size of 12 nm. These suspensions or dispersions may in particular be used at mass concentrations of approximately 15 to approximately 40%. Surface-modified silica nanoparticle grades are also available, such as those marketed by NISSAN CHEMICAL under the references MEK-EC-2140Z or MEK-AC-2202 or MEK-AC-4130Y, functionalized to be compatible with acrylate or methacrylate monomers and oligomers, with particle sizes from 12 to 50 nm. These references are dispersions in methyl ethyl ketone, but other references offer dispersions in isopropanol, for example. BYK also markets products of this nature, for example the reference NANOBYK®-3652, which is available in a mixture of methoxypropylacetate / methoxypropanol solvents. Examples of aqueous colloidal suspensions are also marketed by NISSAN CHEMICAL in the SNOWTEX® range. Dispersions of silica nanoparticles are thus available in alkaline aqueous suspensions such as the ST-XS, ST-S, ST-30, ST-50-T references with particle sizes from 5 to 22 nm and spherical shapes for mass concentrations of approximately 20 to approximately 48%. Non-spherical nanoparticle references are also available such as the ST-LIP reference with a size of approximately 12 nm, an elongated shape, and a mass concentration of 20%. These dispersions are characterized by Na counterions. Other ammonia suspension dispersions are available with reference ST-NXS, ST-NS, ST-N and ST-N-40 having particle sizes from about 5 to about 22 nm, mass concentration from 15 to 40%.Silica nanoparticles in acidic aqueous media are also available through the Snowtex® O and Snowtex® AK ranges. Aqueous colloidal silica dispersions are also available at 40% mass concentration with the reference LUDOX® AS-40, typically of basic pH (in alkaline NaOH medium). Apart from supplies of commercial products, the person skilled in the art may also refer to preparation protocols described in the literature. Protocols for the preparation of colloidal suspensions are thus described in "Colloidal Silica Particle Synthesis and Future Industrial Manufacturing Pathways: A Review" (Ind. Eng. Chem. Res., 2016, 55, 33, 8891-8913, Emily DER Hyde et al.) or in "Preparation of Stable Colloidal Silica with Controlled Size Nano Spheres from Sodium Silicate Solution" (IOP Conf. Series: Materials Science and Engineering 395 (2018) 012017, S. Winardi et al). These protocols make it possible to have colloidal silica suspensions stabilized with different counterions such as Na + , K + , NH4 + , etc. Silica nanoparticles are advantageously used in a functionalized form. In one embodiment, the suspension of silica nanoparticles is chosen from dispersions in aqueous phase or in alcoholic medium, preferably in an alcohol chosen in particular from methanol or ethanol or isopropanol or a mixture of the 3. Advantageously, the mass percentage of SiC>2 in this dispersion is between approximately 1.5% and approximately 65%, in particular between approximately 3% and approximately 50%, preferably between approximately 15 and approximately 45%. The dispersion solvent of the nanoparticles may be methanol, ethanol or isopropanol, or preferably a mixture of water and methanol, ethanol or isopropanol. In particular, the functionalization of the nanoparticles is carried out with a water:alcohol mass ratio of between approximately 0.01 and approximately 4, preferably between approximately 0.05 and approximately 2, preferably between approximately 0.15 and approximately 1. The desired balance between the share of the different solvents is obtained either directly from the conditions of preparation of the suspensions or dispersions of silica nanoparticles or from the characteristics of commercial products having the specified characteristics, or from dilution to achieve the desired solvent ratios, or from solvent exchange carried out by concentrating the colloidal suspension prepared in a given solvent to then transfer by addition into a solvent mixture with the desired ratios. In all cases, a solvent composition or a solvent change procedure will ensure that the stability of the nanoparticles is guaranteed. The functionalization of the nanoparticles is carried out in the presence of a functionalizing agent of alkoxysilane type, notably chosen from the list below and, in particular, at a mass ratio [functionalizing agent]: SiC>2 of between approximately 0.01 and approximately 20, preferably between approximately 1 and approximately 15%, advantageously between approximately 2 and approximately 10%. The functionalizing agent may be an alkoxysilane of trialkoxysilane type, in particular of formula R 1 -If(OR 2 )a where R 2 is typically a hydrolyzable group such as methoxy, ethoxy, propoxy, iso-propoxy, butoxy; R 1 is a radical or an organic chain chosen from H, a linear or branched organic radical of alkyl type (in particular from 1 to 30 C, preferably from 1 to 12 C), cycloalkyl (in particular from 5 to 7 C), alkenyl (in particular from 1 to 30 C, preferably from 1 to 12 C), optionally comprising heteroatoms such as O, S, N; R 1may in particular be: an oxypropyl or thiopropyl group, for example methacryloyloxypropyl or glycidoxypropyl, an allyl group, a vinyl group, an aromatic or polyaromatic cycle, such as for example phenyl, bi-phenyl, naphthyl or phenanthrene; all of the groups may be substituted or not.Examples of these silanes: triethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, propyl trimethoxysilane, propyltriethoxysilane, n-butyl trimethoxysilane, n-butyl-triethoxysilane, dodecyltrimethoxysilane, dodecyltrimethoxysilane, decyltrimethoxysilane, octa-decyltrimethoxysilane, methyldiethoxyvinylsilane, phenyltrimethoxysilane, phenantrene-9-triethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, acryloxypropyltrimethoxysilane, allyltrimethoxysilane, epoxycyclohexylethyltrimethoxysilane, , 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, nonafluorohexyltriethoxysilane, trimethoxy (3,3,3-trifluoropropyl)silane, 3-chloropropyltriethoxysilane, chloromethyltriethoxysilane, y-mercaptopropyltrimethoxysilane and combinations of these compounds. Preferably, the following are used: triethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, n-butyl trimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, or mercaptopropyltrimethoxysilane. The functionalizing agent may be an alkoxysilane of the dialkoxysilane type, in particular of formula R 3 2-If(OR 2 )2 where R 2 is typically a hydrolyzable group such as methoxy, ethoxy, propoxy, iso-propoxy, butoxy, R 3 is a radical or an organic chain chosen from H, a linear or branched organic radical of the alkyl type (in particular from 1 to 30 C, preferably from 1 to 12 C), cycloalkyl (in particular from 5 to 7 C), alkenyl (in particular from 1 to 30 C, preferably from 1 to 12 C), optionally comprising heteroatoms such as O, S, N; R 3may in particular be: an oxypropyl or thiopropyl group, for example methacryloyloxypropyl or glycidoxypropyl, an allyl group, a vinyl group, an aromatic or polyaromatic cycle, such as for example phenyl, bi-phenyl, naphthyl or phenanthrene; all of the groups may be substituted or not. Examples of these silanes: dimethyldiethoxysilane, dimethyldiethoxysilane, 3- (glycidoxypropyl)methyldiethoxysilane, diisobutyldiethoxysilane, dodecylmethyldiethoxysilane, vinylmethyldiethoxysilane, 3-aminopropylmethyldiethoxysilane, (mercaptomethyl)methyldiethoxysilane, (3-isocyanopropylmethyldiethoxysilane), n-(-aminoethyl)3-(aminopropylmethyldiethoxysilane), diethyldiethoxysilane, (methacryloxymethyl)methyldiethoxysilane, n-octadecylmethyldiethoxysilane, n-octylmethyldiethoxysilane, phenylmethyldiethoxysilane, methyldiethoxysilane, (3-acryloxypropyl)methyldiethoxysilane, methacryloxypropylmethyldiethoxysilane, diphenyldiethoxysilane, (3,3- dimethylbutyl)methyldiethoxysilane, phenyldiethoxysilane, vinylphenyldiethoxysilane, diphenyldiethoxysilane, bis(pentafluorophenyl)dimethoxysilane, (3-glycidoxypropyl)methyldimethoxysilane, diisobutyldimethoxysilane, diisopropyldimethoxysilane, vinylmethyldimethoxysilane, phenylmethyldimethoxysilane, 3-chloropropylmethyldimethoxysilane, n-methylaminopropylmethyldimethoxysilane, 3-mercaptopropylmethyldimethoxysilane,di-n-octyldimethoxysilane, (methacryloxymethyl)methyldimethoxysilane, isobutylmethyldimethoxysilane, di-n-butyldimethoxysilane, allylmethyldimethoxysilane, dimethyldimethoxysilane, diphenyldimethoxysilane, bis(pentafluorophenyl)dimethoxysilane, methyldimethoxysilane, cyclohexylmethyldimethoxysilane, or a combination of these products. Preferably, the following are used: dimethyldiethoxysilane, dimethyldiethoxysilane, 3- (glycidoxypropyl)methyldiethoxysilane, vinylmethyldiethoxysilane, 3- aminopropylmethyldiethoxysilane, (mercaptomethyl)methyldiethoxysilane, diethyldiethoxysilane, phenylmethyldiethoxysilane, methacryloxypropylmethyldiethoxysilane, diphenyldiethoxysilane, 3-mercaptopropylmethyldimethoxysilane, cyclohexylmethyldimethoxysilane. The functionalizing agent may be an alkoxysilane of monoalkoxysilane type, in particular of formula R 3 3-SiOR 2 where R 2is typically a hydrolyzable group such as methoxy, ethoxy, propoxy, iso-propoxy, butoxy, R 3 is a radical or an organic chain chosen from H, a linear or branched organic radical of the alkyl type (in particular from 1 to 30 C, preferably from 1 to 12 C), cycloalkyl (in particular from 5 to 7 C), alkenyl (in particular from 1 to 30 C, preferably from 1 to 12 C), optionally comprising heteroatoms such as O, S, N; R 1may in particular be: an oxypropyl or thiopropyl group, for example methacryloyloxypropyl or glycidoxypropyl, an allyl group, a vinyl group, an aromatic or polyaromatic cycle, such as for example phenyl, bi-phenyl, naphthyl or phenanthrene; all of the groups may be substituted or not. Examples of these silanes: trimethylmethoxysilane, trimethoxyethoxysilane, vinyldimethylethoxysilane, 3- (glycidoxypropyl)dimethylethoxysilane, phenyldimethylethoxysilane, methacryloylpropyldimethylethoxysilane, dimethylethoxysilane, 1-amino-2(- dimethylethoxysilyl)propane, y-mercaptopropylmethyl monomethoxysilane. Preferably, the following are used: trimethylmethoxysilane, trimethoxyethoxysilane, 3-(glycidoxypropyl)dimethylethoxysilane, methacryloylpropyldimethylethoxysilane, dimethylethoxysilane. The functionalizing agent may also be a product of the silazane family, such as hexamethyldisilazane (HMDS), tetramethyldilazane, disilazane, alone or in combination. Several (at least 2) different agents can be used for functionalization. According to this preferred mode of functionalization, the dispersion of nanoparticles is optionally modified so as to be composed of solvents with the ratios indicated previously. The functionalizing agents are reacted with the colloidal suspension and the functionalization can be carried out in acidic conditions, by adding organic or mineral acids, or in basic conditions by adding mineral or organic bases. The acids used are strong acids or weak acids. Suitable acids are typically mineral acids, such as HCl, HNO3, H2SO4, H3PO4, or organic acids, such as, for example, acetic acid, propanoic acid, butanoic acid, citric acid, oxalic acid, lactic acid, maleic acid, fumaric acid, itaconic acid or a mixture of these acids. The bases used are typically NaOH, KOH, NH4OH, triethylamine, tripropylamine, tributylamine, nucleophilic agents such as fluorides (KF, NH4F). In the case of weak acids, molar ratios of acid: mol (functionalizing agent) + mol SiOH of between 2 and 100%, preferably between 15 and 75%, are used. In the case of strong or basic acids, molar ratios of acid: mol (functionalizing agent) + mol SiOH of between 0.01 and 15%, preferably between 0.1% and 10%, preferably between 1% and 8% will be used. The functionalization reaction can be carried out at a temperature between approximately 10°C and approximately 120°C, preferably between approximately 20°C and approximately 90°C. The duration of the functionalization reaction can be between 3 and 96 h, preferably between 7 and 20 h, for example for a duration of approximately 15 h. The reaction mixture can then be brought back to room temperature and the pH can be advantageously stabilized between 4 and 8, preferably between 4 and 6 by adding, if necessary, the acids or bases among those mentioned above. Functionalization protocols are provided in particular in the Senani thesis, 2004 (Organosilanes / Precipitation Silica Interaction, from hydro-alcoholic medium to aqueous medium, https: / / theses.hal. science / tel-00012113), but also in W020041041131, EP147934, US6025455 following functionalization protocols in acidic route or in the presence of dehydrating agents such as trimethylorthoformate. Basic route functionalization protocols are finally described in W02009133264 in the presence of hexamethyl disilazane. (C) Alkoxysilane: The alkoxysilane (C) can in particular be of the tetraalkoxysilane, trialkoxysilane or dialkoxysilane type. One or more silanes of each of these three categories can be used, or mixtures of silanes of several categories: tetraalkoxysilane and trialkoxysilane, dialkoxysilane and tetraalkoxysilane, trialkoxysilane and dialkoxysilane, tetraalkoxysilane, trialkoxysilane and dialkoxysilane. These silanes in particular meet the same definitions as those given under (A). Examples of silanes are in particular chosen from: tetramethoxysilane, tetraethoxysilane, triethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, propyl trimethoxysilane, propyltriethoxysilane, butyltriethoxysilane, methyldiethoxyvinylsilane, phenyltrimethoxysilane, vinyltrimethoxysilane, 3 - glycidoxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, 1H, 1H, 2H, 2H - perfluorodecyltriethoxysilane, methacryloxypropyltriethoxysilane, acryloxypropyltrimethoxysilane, dimethyldiethoxysilane, dimethyldiethoxysilane, 3- (glycidoxypropyl)methyldiethoxysilane, dodecylmethyldiethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-mercap(mercaptomethyl)methyldiethoxysilane, 3-isocyanotopropylmtriethoxysilane, 3-isocyanotopropylmethyldiethoxysilane, n-octadecylmethyldiethoxysilane, (acryloxypropyl)methyldiethoxysilane, methacryloxypropylmethyldiethoxysilane, phenyldiethoxysilane, vinylphenyldiethoxysilane, diphenyldiethoxysilane, (glycidoxypropyl)methyldimethoxysilane, bis(pentafluorophenyl)dimethoxysilane, cyclohexylmethyldimethoxysilane or any mixture of these compounds. Preferably, the following are used: tetramethoxysilane, tetraethoxysilane, triethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, methacryloxypropyltriethoxysilane, acryloxypropyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, (3-Mercaptopropyl)trimethoxysilane, dimethyldiethoxysilane, 3-(glycidoxypropyl)methyldiethoxysilane. The alkoxysilane(s) are added pure, in particular with typical purities of more than 97%, or previously dissolved in a solvent or mixture of solvents. The solvent(s) are in particular chosen from 1,4-dioxane, dimethylsulfoxide, ethanol, methanol, ethyl acetate, 1,2-propanediol, 1-propanol, 2-methoxyethanol, 2-methyl-2-propanol, 1-methoxy-2-propanol, 2-propanol, 4-methyl-2-pentanone, methyl ethyl ketone, methyl propyl ketone, n-methylpyrrolidone-2, tetrahydrofuran, 2-isopropoxyethanol, propylene glycol methyl ether acetate, 2-butoxyethanol, Di(propylene glycol) dimethyl ether, Ethyl-2-hexanol-1, preferably ethanol, ethyl acetate, 1-propanol, 1-methoxy-2-propanol, 2-propanol, 4-methyl-2-pentanone, 2-isopropoxyethanol, 2-butoxyethanol. (D) Solvent mixture: In order to ensure good suitability for spray application on flat or 3D geometry surfaces, at least one mixture (D) of two organic solvents having different boiling points at atmospheric pressure (typically at 1013.25 mmPa or 760 mmHg) is advantageously added to the condensate hydrolyzate (A) and to the colloidal suspension (B). The solvent mixture preferably comprises at least one solvent having a boiling point between 110°C and 140°C, inclusive, and at least one solvent having a boiling point above 140°C, typically above 140°C and less than or equal to 190°C. The boiling point of the solvents is typically evaluated at atmospheric pressure. atmospheric preferably by calorimetry, more particularly by DSC (differential scanning calorimetry). Preferably, two solvents having a boiling point difference greater than or equal to approximately 20°C, in particular between approximately 20 and approximately 70°C, are used. As examples, solvents suitable for the anti-reflective composition, having a boiling point above 140°C are (without being exhaustive): ethylene glycol monoisopropyl ether (CAS 109-59-1) with a boiling point of 143°C propylene glycol methyl ether acetate (PGMEA) (CAS 108-65-6) with a boiling point of 146.4°C 2-butoxyethanol (CAS 111-76-2) boiling point 171 °C di(propylene glycol) dimethyl ether (CAS 111109-77-4) boiling point 175°C ethyl-2-hexanol-1 (CAS 104-76-7) boiling point 186°C Suitable solvents for anti-reflective composition, having a boiling point between 110°C and 140°C are, for example (without being exhaustive): 1-butanol (CAS 71-36-3) boiling point 117.7°C 1-methoxy-2-propanol (CAS 107-98-2) with a boiling point of 120°C. The combination of solvents used in composition (D) can be adapted, in terms of surface tension, to the surface energies of the substrates to avoid wettability problems, as well as in terms of chemical compatibility (degradation of the substrate). The solvents used are also compatible with an objective of stability of the colloids over a period of 48 hours. In one embodiment, one or more solvents are added to facilitate dispersion or stability, such as methanol, ethanol, 1-propanol, 2-propanol or water, without this being exhaustive. In one embodiment, ethylene glycol monoisopropyl ether and 1-butanol are used, optionally with such an additional solvent, such as propanol (eg 1-propanol) or ethanol. Advantageously, for a spray application, the mass proportion of solvents having a boiling point between 110 and 140°C is in particular between 7 and 40%, preferably between 15 and 30%. In the case of an application by dipping or immersion ("dip-coating"), this is between 50 and 99%, preferably between 60 and 90%. In spray, the mass proportion of solvents having a boiling point between 140°C and 190°C is in particular between 10% and 55%, preferably between 15% and 50%. In dip coating, the latter will be between 2 and 50%, preferably between 5 and 30%. The additional solvent(s) will have mass proportions between 0.01% and 70%, more particularly from 0.01% to 15% in the case of water, from 0.5% to 65% in the case of ethanol, from 0.01 to 20% in the case of 1-propanol. The mass proportion of solvents is given in relation to the total mass of solvent. The varnish composition is therefore preferably such that: - the mass proportion of solvents having a boiling point of between 110 and 140°C, relative to the total mass of solvents, is between 7 and 40%, and the mass proportion of solvents having a boiling point of between 140°C and 190°C, relative to the total mass of solvents, is between 10% and 55%; in particular for application by spraying, or - the mass proportion of solvents having a boiling point between 110 and 140°C, relative to the total mass of solvents, is between 50 and 99%, and the mass proportion of solvents having a boiling point between 140°C and 190°C, relative to the total mass of solvents, is between 2% and 50%, in particular for an application by immersion (dip). As will be seen, by playing the role of diluent of the varnish composition, the quantity of these solvents is a means to adjust the dry extract of this composition. Dry extract (ES%) In this presentation, the terms "dry extract" and "dry mass" are used interchangeably. The colloidal suspension (B), the hydrolyzate-condensate (A) and the alkoxysilane(s) (C) are the essential or sole basis of the dry extract of the varnish composition. The value of the latter is compatible with the preparation of an anti-reflective varnish formulation or composition according to the invention having a dry extract adapted to the desired final application and in particular to the application parameters in the spray method (spraying). The organic solvents of the mixture (D) can be used to adjust the final dry extract in the anti-reflective varnish formulation or composition to be applied, in particular with regard to the spray application parameters. Generally speaking, the final dry extract ES% of the anti-reflective composition to be applied may be between approximately 0.4 and approximately 10%. For the spraying process, an ES% of about 1 to about 10%, in particular about 1.9 to about 6%, preferably between about 2.2 and about 5% is preferred. Such a dry extract makes it possible to obtain a single-layer anti-reflection coating whose optical centering is between about 150 nm and about 3000 nm. In a suitable spray head diagram whose movement is controlled by a robot (Cartesian robot, 6-axis robot, etc.), the speed of The robot's movement will, for example, be a simple parameter to adapt the quantity of material deposited on the surface to be coated. Depending on the intended application, the desired optical performance in terms of the level of reflection obtained at the minimum reflection will meet different specifications. The minimum will be lower as the porosity in the layer is increased. To this end, the contribution to the final dry mass (dry extract) in the anti-reflective formulation resulting from the colloidal suspension (B) will be favored to the detriment of the contribution of component (A). Preferably, the ratio of mass of dry matter from (A) to the mass of dry matter from (B) may be more particularly between approximately 5% and approximately 50%, preferably between approximately 8% and approximately 45%; and / or the ratio of dry matter from the alkoxysilane or the mixture of alkoxysilanes (C) to the dry matter from (A) is more particularly between approximately 1% and approximately 150%, ideally between approximately 3 and approximately 30%. This is particularly well suited to application by spray. In dip-coating, an ES% of between about 2% and about 10% is preferred, preferably between about 2.5% and about 8.5%, preferably between about 2.9 and about 6.5%. Preparation of the composition and its application: The method for preparing the anti-reflective composition comprises mixing the various components. Preferably, in a first step, the hydrolyzate-condensate (A), the colloidal suspension (B) and the solvent mixture (D) are mixed. The medium is stirred so as to obtain a homogeneous mixture of the various dissolved components and the suspended particles. Typically, stirring or mixing may require a duration of a few minutes to 1 hour. In a second step, the alkoxysilane or the mixture of alkoxysilanes (C) is added. Optionally, it may be envisaged to add other useful additives or components, for example to improve the wetting of the varnish composition and / or, for example, to catalyze the polymerization reaction after deposition.When all the components are added, the mixture is stirred, in particular for several hours, preferably for at least 24 h, for example between 24 and 48 h, optionally under vacuum for part of the reaction time, typically between 1 bar and 50 mbar, preferably between 800 and 200 mbar, preferably between 600 and 300 mbar, before carrying out the application on the substrate. The application on the substrate is preferably carried out at a thermostatically controlled temperature, in particular between approximately 10°C and approximately 80°C, preferably between approximately 20°C and approximately 50°C. In one embodiment, just before spray application, the dry extract of the varnish composition can again be checked and / or adjusted, typically with the aim of the dry extract targets specified above. In a preferred embodiment of the invention, an anti-reflective varnish composition of the invention with a compliant dry extract, in particular between 5 and 10%, is prepared in the following manner: a hydrolyzate-condensate (A) is prepared according to the protocol described and has dry extract characteristics of between approximately 65% ​​and approximately 90%. This hydrolyzate-condensate may also have a condensation rate Te > approximately 75%; a colloidal suspension (B) is prepared according to the protocol described and has dry extract characteristics of between approximately 5% and approximately 20%; a mixture of solvents (D) having, for at least one of the solvents, a boiling point between 110 and 140°C and, for at least one other of the solvents, a boiling point above 140°C, and a boiling point difference greater than or equal to approximately 20°C, in particular between approximately 20 and approximately 70°C, according to the rule described above, is prepared. Components (A), (B) and (D) are mixed, preferably at a thermostatically controlled temperature between about 20 and about 30°C. The mixing can be easily carried out with standard means, for example a stirring paddle. The proportions can be as follows: for (A): mass proportion in the composition between about 0.4% and about 5%, preferably between 0.75 and 3.5% for (B): mass proportion in the composition between about 5 and about 75%, preferably between 15% and 35% for (D): mass proportion in the composition between about 25 and about 75%. Component (C), namely the alkoxysilane or the mixture of alkoxysilanes, and any possible additive relevant to the intended application, are then added to the mixture obtained, and the mixture is stirred preferably at a thermostatically controlled temperature between 20°C and 40°C for several hours, preferably at least 24 hours. The quantity of component (C) is adjusted to achieve the target extracts, in particular the dry extracts mentioned above. According to one method, after having carried out the mixing at thermostatic temperature presented above, a measurement of the dry extract is carried out on a sample, and said extracts are adjusted as needed by adding sufficient quantities of the solvents from the mixture (D). Preferably, the aim is to produce a dry extract that makes it easy to adjust the composition to the application conditions. It is better to have a higher dry extract, and to carry out a dilution, rather than having to concentrate a composition having too low a dry extract. Application by spraying or spraying, using an electrostatic rotating bowl A method according to the invention is shown schematically in Figures 1 and 2. It comprises the application of a varnish composition as mentioned above on a transparent substrate 2. This substrate is advantageously of the type mentioned above and made of an electrically insulating material, such as glass or polycarbonate. This substrate may be formed by a flat plate, as shown in Figure 1, or, alternatively, have one or more kinked surfaces. Advantageously, the substrate 2 is placed on a conductive table 4 which is connected to ground by a conductive cable 42. The substrate 2 and the table 4 are fixed during the implementation of the method of applying the varnish composition. The method is implemented with a sprayer 6 which projects the varnish composition towards a surface S2 of the substrate 2 which is turned towards this sprayer. The sprayer 6 is mounted at the end of the arm of a multi-axis robot (not shown). The robot's function is to move the sprayer relative to the substrate 2. In a variant not shown, the sprayer 6 is fixed and the substrate 2 is mounted at the end of the arm of a multi-axis robot which moves it during the implementation of the method of applying the varnish composition. In all cases, there is a relative displacement between the substrate 2 and the sprayer 6, during the application of the varnish composition. In the example, the sprayer 6 is equipped with a rotating bowl 8 whose edge is denoted 82. This edge 82 is circular and its diameter D82 is preferably between 35 and 65 mm. The rotating bowl is driven in rotation, around an axis of rotation A6 defined by the sprayer 6, by means of a turbine not shown which is integrated into the sprayer 6 and which can operate over a range of rotation speeds between 20,000 and 80,000 rpm. The sprayer is supplied from a reservoir 10 of varnish composition, through a supply pump 12 inserted on a conduit 14 which connects the reservoir 10 to the sprayer 6. The pump is adjustable and makes it possible to supply the sprayer with a flow rate of varnish composition which is adjustable, for example between 20 and 150 cc / min. The sprayer 6 is also supplied with high voltage from a voltage generator 20 whose output voltage has an absolute value adjustable between 40 and 100 kV. A high voltage cable 24 connects the voltage generator 10 to the sprayer 6. Thus, the sprayer 6 is of the electrostatic type and makes it possible to apply a high voltage to the cloud N of droplets of varnish composition leaving the edge 82 of the bowl 8. In the example, the sprayer is also equipped with a shaping air skirt 62 which makes it possible to direct a flow F62 of shaping air onto the cloud of droplets N. This flow of air makes it possible to control the shape of the cloud N. The shaping air skirt is supplied from a source of pressurized air 30 via a conduit 34. By way of non-limiting example, the sprayer 6 may comply with the technical teaching of WO-A-2010 / 037972. Advantageously, the air from the air source 30 can be used to rotate the rotor of the turbine, which is then an air turbine type. The bowl 82 is rotationally fixed to the rotor of the air turbine. The ES% of the varnish composition is preferably adapted to the type of the spray gun, for example on the order of 1.9% when the spray gun 6 has no rotating bowl and on the order of 3% when the spray gun 6 has a rotating bowl. With the rotating bowl, the dry extract is in particular between 1.5 and 6%, preferably between 1.8 and 4%, more preferably between 1.9 and 3.8%. In a manner known per se, the high voltage supplied by the generator 20 makes it possible to electrostatically charge the cloud N of droplets leaving the edge 82 of the bowl 8. The electrostatic charge can be transmitted to the cloud N directly, by bringing the bowl to the high voltage, or indirectly, by means of electrodes not shown which charge the cloud N by the Coanda effect. The high voltage applied is preferably negative. The applied high voltage has the effect of homogenizing the distribution of the varnish composition droplets in the N cloud. Indeed, in the absence of high voltage, the droplets can be of very variable sizes, the largest droplets tending to burst, while the finest droplets do not tend to recombine. The high voltage applied to the N cloud is chosen with an absolute value between 30 and 70 kV, which allows effective homogenization of the N cloud droplets, without deforming this cloud, nor disturbing the expected aeraulic phenomena. We note d6 a distance measured parallel to the axis of rotation A6, between the edge 82 of the bowl 8 and the surface S2. Advantageously, to limit the risks of premature drying of the varnish composition, the distance d6 is chosen to be less than 20 cm, preferably less than 18 cm. A problem to be solved when applying the varnish composition to the substrate 2 is the evacuation of the electrostatic charges deposited on the surface S2 with the droplets of varnish composition, taking into account the fact that the material of the substrate 2 is electrically insulating. To do this, the substrate is deposited on a conductive metal structure (for example, the support 4 is conductive) or is connected to ground, which is shown with the numerical reference 42. The trace of the axis A6 in the plane of the surface S2 is represented by a broken line in axis lines in Figure 1 and represents the trajectory T of the sprayer in the reference frame of the substrate 2. This trajectory comprises successive passages PT parallel to each other and which are separated two by two by a distance dT, measured perpendicular to these passages. Each passage PT of the trajectory T induces the deposition of a band B of varnish composition on the surface S2, these bands being parallel to each other (Figure 2). We consider the impact surface of the cloud N of varnish composition on the surface S2. In the example of the figures, this impact surface is an impact disk of which we note <t>l the diameter, as shown in insert A) of figure 2. W50 is the width of a strip of varnish composition deposited on the surface S2, this width being measured at mid-thickness of the strip in question, before drying. The width W50 is visible on the insert B) of figure 2 which is a partial section of the principle of the substrate 2, during the implementation of the method of the invention, this section being taken perpendicular to the direction of the passages PT, therefore to the length of the strips B of varnish composition, before drying of these strips. The width W50 is approximately equal to the diameter <t>L. The distance dT is chosen to be equal to 25% of the width W50. Thus, the application of the varnish composition at a point P2 of the surface S2 takes place in several passes, in the example four passes. In other words, each point P2 of the surface S2 is covered by four strips B, which guarantees total coverage of the surface S2, without gaps, and a constant thickness of the varnish deposited. Alternatively, the distance dT is chosen equal to 33% of the width W50. In this case, each point P2 of the surface S2 is covered by three bands B, which is also satisfactory. If each point on the surface S2 is covered by less than three stripes, there is a real risk of missing or irregular anti-reflective varnish deposited on the surface S2. After applying the layers of varnish composition, they are left to dry, in particular by placing the substrate 2 coated with the varnish composition in an oven whose temperature is between 40°C and 130°C depending on the nature of the substrate for a duration of between 5 and 240 min. The method of the invention can be implemented to cover all or part of the surface S2. After applying the anti-reflective varnish by spraying onto a plastic or glass surface, the wet layer is desolventized (desolvation) and, generally, subjected to a baking step in an oven or thermal furnace or to infrared or UV / Visible radiation. The desolvation step can typically be carried out in a spray booth whose typical conditions include, in particular, vertical or horizontal movement of filtered air, at a temperature of between 18°C ​​and 26°C, preferably between 20°C and 24°C, preferably between 20 and 22°C and at a relative humidity level greater than 40%, preferably between 45% and 75%, preferably between 55 and 70%. The desolvation time is in this case typically between 10 s and 5 minutes depending on the thickness of the deposited layer and the desired optical centering. Desolvation can also be carried out in "hot" conditions, typically between 50°C and 130°C, the upper limit being limited by the thermal resistance of the material (typically the glass transition temperature for thermoplastics). The temperatures reached at the surface of the material will preferably be between 50°C and 90°C, preferably between 60 and 80°C so as to limit exposure times to approximately 5 minutes or less. Infrared drying equipment can be equipped with short infrared, medium infrared, long infrared radiants, such as those marketed by the companies Tl FLEX, Sunkiss Matherm or Dr Fischer. The curing step will be carried out using various methods known to those skilled in the art. Thus, for plastic materials such as polycarbonate and PMMA, curing can be carried out in a convection oven at temperatures not exceeding the glass transition temperatures (approximately 120°C for PC, approximately 80°C for PMMA) for typical durations of 10 to 90 minutes. The treated parts can also be placed in an infrared oven, for example those offered by the manufacturers mentioned above. Those skilled in the art will be able to quantify the progress of the polymerization of the deposited layers by FTIR-type analyses to correlate the power of the required radiants and the time spent in the oven compared to the conditions in a conventional convection oven. Typically, an electric radiant of 20 kW / m 2 allows for a cooking time divided by 2 to 3 compared to the exposure time in a forced convection oven. For photopolymerizable anti-reflective varnish formulations, the layers after desolvation can be exposed to UV radiation produced by Mercury or Xenon lamps, such as those marketed by the company 1ST Metz, or LED lamps typically irradiating at 382 or 395 nm with typical irradiation energies in the UVA range of 0.5 to 3 J / cm 2 . Application by dip-coating or immersion: The anti-reflective formulations according to the invention can be applied by dip-coating, with the solvent and ES% conditions described above. To carry out a deposit by dip coating, the substrate to be covered will be immersed in a bath preferably using a 1-axis robot (vertical axis) and using tools (such as pliers, hooks, belts, etc.) and raised from the bath at a controlled speed in order to control the thickness of the deposit. Equipment such as those sold by the company Nadetech with reference ND-DC-150 can be used or any equipment of the type described in HardwareX (Volume 12, October 2022, e00364), by Christy Dunlap et al. Withdrawal speeds between 0.5 mm / s and 5 mm / s are generally applied, preferably between 1 and 4 mm / s depending on the knowledge of the person skilled in the art.The environmental conditions (temperature, humidity), desolvation of solvents after application by dip-coating and baking are similar to those described for spray application. In order to characterize the thickness homogeneities on the deposits made according to the methods of the invention, we will use a quadratic roughness defined either from the following formula: where Rq is the quadratic roughness (or RMS), Z(x) is the variation in depth of the surface according to a scan in the x axis (axis in the plane of the characterized surface), measured for example using an Atomic Force Microscope. We can also use a quadratic roughness defined from the following formula R ,= J n where zi is the thickness or optical centering, as measured using a fiber spectrophotometer, measured at a set of points crisscrossing the characterized surface. These notions of roughness will appear in the examples in particular. Examples 1 A, 1 B and 2: The preparation of anti-reflective formulations is based on the preparation of two sub-components (MSG1 and SC1) before mixing them. Preparation of the anti-reflective composition ART 1 The preparation of the subcomponents and composition ART 1 is carried out with the following quantities of reagents (Table 1) and according to the following protocols. [Table 1] Preparation of MSG1 matrix (hydrolyzate-condensate): In a 500 mL flask, the following products are successively introduced: MTEOS, DMDEOS. The mixture, while stirring, is thermostated for 5 min at 40°C. Then the Hydrochloric Acid HCl solution at pH 3.5 is added. Stirring is continued for 2 hours and then the mixture is brought to 80°C for 13 hours. The mixture is then brought to room temperature. 250 mL of NaCl saline solution (8 wt% CAS No. 7647-14-5) is added to the mixture and stirred. Extraction is then carried out using a separating funnel with 3 equivalent volumes of diethyl ether (CAS No. 60-29-7), which are then combined. The diethyl ether solution is concentrated using a rotary evaporator. The ES% is checked at the end of this step. Following the method explained above, a dry extract of 80% is obtained for the hydrolyzate-condensate. Preparation of SC1 matrix (colloidal suspension): In a 250 mL flask equipped with a condensation column, immersed in a bath at 25°C, ethanol, water and AcOH are added successively, then left stirring for 10 minutes. The SiO2 NP suspension (40%) is then introduced and left stirring again for 15 minutes. Finally, the MTMS is added and the mixture is then brought to reflux at 70°C for 20 hours. The temperature is then lowered to 25°C. The ES% of the suspension is characterized and is measured at 8.5% Formulation of ART 1 composition: In a 1 L flask, the MSG1 material is introduced. Then, at room temperature, SC1, EGME, butanol and propanol are added successively. The mixture is left stirring until the MSG1 is completely dissolved. GPTS and MTMS are then added and left stirring for 10 minutes, then AcOH is added. The flask is thermostated at 35°C and stirred for 24 hours. The reaction mixture is then evacuated to 400 mbar for 90 minutes. The contents are then transferred into a white polypropylene jar and stored for 10 days. The ES% is then measured at 6.5%. Formulation of ART1 B composition The ART1 B formulation is a variant of the ART1 formulation, more specifically dedicated to dip coating applications. The components required for the preparation of ART1 B formulation are described in Table 2. [Table 2] The preparation is carried out as follows: The MSG1 material is introduced into a 1 L flask. Then, butanol and propanol are added successively at room temperature. The mixture is left stirring until the MSG1 is completely dissolved. GPTS and MTMS are then added and stirred for 10 minutes. AcOH is then added to the mixture. The flask is thermostated at 30°C and stirred for 14 hours. The reaction mixture is then evacuated to 40°C at 400 mbar for 60 minutes. The mixture is stored in a white polypropylene jar and stored for 6 days. The ES% is measured at 6.21%. The ES% is then adjusted to 4.5% by adding butanol. Application of spray varnish on PC support In the 2 spraying examples below, the spraying conditions and parameters were determined to seek optical centering around 905 nm. • Application by pneumatic spray (Example No. 1A) ART 1 varnish is diluted to bring its dry extract to 1.9% with a mixture of EGME / Propanol / Butanol 15 / 25 / 60 (in mass %). The support is a 2 mm thick extruded PC Vindulex polycarbonate plate. An A3 PC plate is cleaned using a viscose cloth soaked in isopropanol (CAS: 67-63-0). In a humidity and temperature controlled environment (T 22°C + / -2°C and RH 60% + / -5%), the PC plate is placed on a table covered with a sheet of aluminum foil. The PC plate to be treated is raised by 4 mm using a PC contour. A pneumatic spray equipped with a 1.5 mm diameter nozzle is attached to a multi-axis robot. The sprayer is positioned vertically to the PC plate at 20 cm and is programmed to start a stroke at 20 cm from the side in the length of the A3 plate. After application, the plate is desolventized for 3 minutes in the same environment before being placed in an oven at 120°C for 1 hour. • Application by pneumatic spray (Example No. 1 B) This example is carried out in the same way as example 1A but by connecting the pneumatic equipment to a High Voltage unit (GRACO XP60 type equipment, 60kV) positioned 20 cm from the PC substrate and by carrying out a manual application, ensuring the electrical isolation of the assembly. The conditions are determined for optical centering around 905 nm. • Application by electrostatic rotating bowl spray with 35 mm bowl (Example no. 2) The ART1 varnish is diluted to bring its ES% to 3% with a mixture of EGME / Propanol / Butanol 15 / 20 / 65 (in mass %). The support is an extruded PC Vindulex polycarbonate sheet with a thickness of 2 mm. An A3-sized PC sheet is prepared similarly to Example 1. In a controlled environment in humidity and temperature (T 22°C + / -2°C and RH 60% + / -5%), and with a vertical air movement with a speed of 0.3 m / s, the PC plate is positioned on a table covered with a sheet of aluminum foil. The PC plate to be treated is raised by 4 mm using a PC contour. Finally, the plate is connected to an electrical ground. The spray nozzle is typically positioned at a distance of 15 cm normal to the surface of the part to be treated. The treatment is carried out using a 35 mm bowl. The parameters are determined to achieve a centering around 905 nm. The characteristics of the deposits obtained are collected in General Table 3, grouping the results for all the examples presented. The measured characteristics are: Optical centering in nm over the wavelength range of 400 to 1100 nm Homogeneity in optical centering o% (nm) The minimum reflectance of the surface R m in over a wavelength range of 400 to 1000 nm in % Homogeneity in R m in on an OR surface The AHaze in %. The gain in UV / Visible / NIR Transmission at targeted optical centering. Centering measures, R m in and AHaze measurements are made at 25 points regularly distributed over a surface of 20 cm x 25 cm and the values ​​indicated in the table are arithmetic means of these 25 measurements. In the case of centering at 1550 nm, the centering indicated in the table corresponds to the minimum reflectance over the 400 nm / 1100 nm range (see values ​​marked with an * in Table 3), the operating zone of the Filmetrics F20 spectrometer used. The gain in UV / Visible / NIR transmission was measured relative to the untreated substrate measured using a UV / Visible / NIR spectrometer. [Table 3] These results show that Example No. 2 is characterized by better homogeneity both in terms of centering and the reflectance level obtained compared to a conventional pneumatic spraying or electrostatic pneumatic spraying. Indeed, a conventional pneumatic spraying such as in Example 1A leads to high centering inhomogeneities of 165 nm which will not be acceptable for the targeted optical applications. In addition, the reflectance level is altered compared to Example 2 where the same formulation is applied by electrostatic spinning bowl, at different ES%. The reflectance level R m It is thus 1.48% in % for Example 1A while it is 1.01% for Example 2, which indicates a better integrity of the ART 1 anti-reflective composition under the conditions of electrostatic spinning bowl, the corollary of which is also a lower AHaze in the case of Example 2 compared to Example 1A. With a lower ES %, required in Example 1A compared to the example, a higher number of passes are required in Example 1A, which alters the optical qualities of the anti-reflective composition. If an electrostatic component is added to the pneumatic spraying (Example 1B), a much better homogeneity is found however outside the characteristics of the composition and the application processes of the invention but the values of AHaze and R m in % are very altered, outside the characteristics of the invention, for a composition similar to Example 2. Furthermore, example no. 2 also leads to a reflectance closest to that obtained by dip-coating (example no. 3), a method characterized by the best homogeneity and the best optical characteristics of the ART1 formulation. This is the anti-reflective layer with the characteristics to be approached. Conversely, example No. 4, based on an anti-reflective composition ART2 not comprising hydrolyzate (A) such as MSG1 prepared according to the characteristics of the anti-reflective composition of the invention but comprising the same reagents as MSG1 reacted directly in the ART2 formulation, is characterized by homogeneity characteristics R m in%, OR, degraded compared to example no. 2 and outside the characteristics of the invention The contribution of a hydrolyzate such as MSG1 is a better stability of the sol-gel composition ART 1 compared to comparative example no. 4 under the same application conditions, the composition ART2 developing more optical diffusion (Haze). Examples 5, 6, 7, 8A, 8B, 9, 10 and 11 give examples of implementations of compositions making it possible to achieve anti-reflective layers with very good homogeneity, for compositions with thermal or UV crosslinking. Example 3 (dip-withdrawal application) of the ART1 B formulation: Application of ART 1 B varnish by dipping-removal on PC support The conditions were determined in order to achieve a deposit with an optical centering around 905 nm. The support is a 2 mm thick extruded PC Vindulex polycarbonate sheet with a surface area of ​​20 cm x 25 cm. The sheet is protected on the back by a protective film, typically made of polyethylene. An adhesive film such as polypropylene adhesive tape is applied along the outer edges of the back to prevent varnish from seeping onto the back. The PC sheet is cleaned in the same way as in examples 1 and 2 on each side. In a humidity and temperature controlled environment (T 22°C + / -2°C and RH 50% + / -5%), the PC plate is positioned vertically, in the height direction on a clamp attached to a 1-axis robot in z above a tank filled with varnish with a volume of 8.75 L and dimensions 25 cm x 10 cm x 35 cm. The tank is thermostatically controlled at 20°C + / - 2°C. The plate is immersed in the bath at a speed of 10 mm / s. The tool (clamp) is not immersed. The plate is left in the bath for 10 seconds before being raised at a constant speed of 1.6 mm / s. When the plate is completely raised out of the bath, it is left suspended for 2 minutes and then placed in a forced convection oven, suspended from a support, and left at 120°C for 1 hour 30 minutes. The tape and protective film on the back are removed after returning to room temperature. The optical characteristics of the PC plate are gathered in Table No. 3 and indicate very good homogeneity in soaking-shrinking with the ART 1 B formulation. Characterization of surface roughness. In order to compare the roughness characteristics of anti-reflective layers obtained on spray-extruded polycarbonate using the electrostatic rotating bowl technique and by dip-shrinking, the plates obtained, for example, in example 2 and example 3 were characterized by: Atomic force microscopy (AFM) using a Digital Instrument DI dimension 3100 (inverted) Optical microscopy using a Mitutoyo Vision Unit microscope equipped with QSPAK processing software according to ISO 4287. These two methodologies allow to characterize the mean square roughnesses on surfaces at different orders of magnitude, at the nanometer scale for AFM and for typical scanned surfaces of 5 pm 2 and at a scale of 500 pm 2 for surfaces scanned for optical microscopy. [Table 4] These characterizations show the good suitability of these methods for obtaining homogeneous layers with good optical characteristics in relation to very similar surface topographies. Example 4 (comparative): Preparation of ART2 composition: In Example 4, the preparation of the anti-reflective formulation is modified compared to Examples 1 and 2. There is no condensate hydrolyzate, only the addition of alkoxysilanes in the general composition. The preparation is carried out with the following quantities of reagents (Table 5) and according to the following protocols. [Table 5] Preparation of the SC1 matrix (colloidal suspension): The SC1 matrix is ​​prepared following the protocol described in examples 1 and 2 Formulation of ART2 composition: In a 1 L flask, MTEOS, DMDEOS and then SC1 are successively introduced. The mixture is left to homogenize while stirring for 5 minutes at room temperature, then the hydrochloric acid solution is added and the mixture is brought to 80°C for 13 hours. The reaction medium is then allowed to return to room temperature and stirred for 18 hours. EGME, butanol, ethanol, GPTS, MTMS and acetic acid are then successively added. The flask is thermostated at 35°C and stirred for 24 hours. The reaction mixture is then evacuated to 400 mbar for 90 minutes. The propanol is then added and the contents are transferred into a white polypropylene jar and stored for 10 days. The ES% is then checked and measured at 6.3%. Application of spray varnish on PC support In the spray example below, the conditions were determined to seek optical centering around 905 nm. • Application by electrostatic rotating bowl spray (Example no. 4) The ART2 varnish is diluted to bring its dry extract to 3% with a mixture of EGME / Propanol / Butanol 15 / 20 / 65 solvents (in mass %). The conditions are otherwise the same as in example 2. The optical characteristics of the PC plates are collected in Table 2. These characteristics indicate a lower homogeneity compared to the ART 1 formulation deposited under similar conditions and degraded optical characteristics. Example 5: Example 5 is based on electrostatic rotating bowl spraying of the ART 1 formulation, which aims to provide an anti-reflection centered around 905 nm with a 50 mm bowl on a Vindulex PC plate. • Application by electrostatic rotating bowl spray with 50 mm bowl: ART 1 varnish is diluted to bring its dry extract to 2.4% with a mixture of EGME / Propanol / Butanol 10 / 20 / 70 solvents (in mass %). The application is carried out with a 50 mm diameter bowl. The spray parameters are determined in a 50 mm bowl to achieve centering around 905 nm. The conditions for preparing the PC plate and drying after spray application are identical to example 2. The optical characteristics of the PC plate are also collected in Table 3. Example 6: Example 6 is based on electrostatic rotating bowl spraying of the ART 1 formulation and aims to provide an anti-reflection centered around 1550 nm with a 35 mm bowl. • Application by electrostatic rotating bowl spray: ART 1 varnish is diluted to bring its dry extract to 3.7% with EGME. The plate, its preparation and positioning, the drying conditions after application, the environmental conditions and the sprayer are identical to Example 2. The parameters applied for spraying and the robot are determined according to the expertise of the person skilled in the art to achieve optical centering at 1550 nm. The results are summarized in Table 3. Example 7: Preparation of the ARUV1 composition: In example 7, the preparation of the anti-reflective formulation is modified compared to the previous examples. It aims to prepare an anti-reflective composition whose cooking will be carried out by a UV process and for plastic substrates of the PC and PMMA type in order to produce an anti-reflective layer in the visible UV range with an optical centering around 530 nm. The preparation is carried out with the following quantities of reagents (Table 6 below) and according to the following protocols. [Table 6] Preparation of MSG2 matrix (hydrolyzate-condensate): In a 500 mL flask, the following products are successively introduced: MTEOS, DMDEOS, GPTS and MPTS. The mixture, while stirring, is thermostated for 5 min at 40°C. The HCl solution at pH 4.5 is then added. Stirring is continued for 30 min and the mixture is then brought to 85°C for 11 h. The mixture is then cooled to room temperature. 250 mL of NaCl saline solution is added to the mixture and extracted, then the diethyl ether solution is concentrated as in Example 2. The ES% is checked and 80.9% is obtained. Preparation of SC2 matrix (colloidal suspension): In a 250 mL flask equipped with a condensation column, immersed in a bath at 25°C, the IPS-ST colloidal solution (30%) is added. Then, ethanol is added successively, AcOH successively, then gradually, over 15 minutes, water. The mixture is left stirring for 10 minutes. Finally, the MPTS is added and the mixture is then brought to reflux at 85°C for 15 hours. The temperature of the mixture is then lowered to 25°C. The ES% of the suspension is characterized and is measured at 7.7%. Formulation of the ARUV1 composition: In a 1 L flask, the MSG2 material is introduced. Then, SC2, EGME, butanol and propanol are added successively at room temperature. Stirring is continued until the MSG2 is completely dissolved. GPTS and MTMS are then added and stirred for 10 minutes. Finally, AcOH is added to the mixture. The mixture is stirred and thermostated at 35°C for 12 h, then for an additional 24 h at 25°C. The ES% is then checked and measured at 3.60%. Application of spray varnish on PC support • Application by electrostatic rotating bowl spray (Example no. 7) The ARUV1 varnish is diluted to bring its dry extract to 2% with a mixture of EGME / Propanol / Butanol 15 / 30 / 55 solvents (in mass %). The support is a 2 mm thick extruded PC Vindulex polycarbonate plate prepared and positioned as in examples 1 and 2. The use of an electrostatic sprayer is also identical to examples 1 and 2. The application is carried out with a 50 mm diameter bowl. After spraying, the coated PC plate is kept under the same environmental conditions for 2 minutes. The plate is then placed in an oven at 80°C for 3 minutes and then exposed under a Mercury type UV lamp (Bulb-H). A dose in the UVA of 2.5 J / cm 2 is applied to the plate. The optical characteristics are listed in Table 3. Examples 8A and 8B: Preparation of the ART3 composition: The preparation of the ART3 formulation aims to prepare an anti-reflective composition for application on float glass and thermal baking. The preparation is carried out with the following quantities of reagents (Table 7) and according to the following protocols. [Table 7] Preparation of MSG3 matrix (hydrolyzate-condensate): In a 500 mL flask, the following products are successively introduced: MTMS, PhTEOS, TEOS. The mixture, while stirring, is thermostated for 5 min at 40°C. Then distilled water is added in which oxalic acid has been previously dissolved. Stirring is continued for 60 min and the mixture is then brought to 75°C for 20 h. The mixture is then brought to room temperature. 250 mL of saline solution is added to the mixture and the diethyl ether solution is extracted and concentrated as in Example 2. An ES% of 90% is measured. Preparation of SC3 matrix (colloidal suspension): In a 500 mL flask equipped with a condensation column, immersed in a bath at 25°C, ethanol, methanol and distilled water are successively introduced. The mixture is thermostated while stirring at 50°C. Ammonia is then added and stirred at 50°C for 5 minutes. TEOS is then added and stirred at 50°C for 10 hours. The flask is then equipped with a Vigreux column connected to a recovery flask filled with distilled water. Reflux is continued until the pH has reached a value of 6.2 + / - 0.5. The temperature is then allowed to drop back to 50°C and the MTEOS is added. The mixture is left stirring for 15 hours at 50°C. The ES% of the colloidal solution is then characterized and 9.88% is measured. Formulation of ART3 composition: In a 1 L flask, the MSG3 material is introduced. Then, at room temperature, EGME, butanol and propanol are added successively. Stirring is continued until the MSG3 is completely dissolved. GPTS and TEOS are then added and stirred for 10 minutes. Finally, AcOH is added to the mixture. The mixture is stirred and thermostated at 45°C for 2 hours, then for an additional 48 hours at 25°C. The ES% is then checked and measured at 6.8%. • Application by electrostatic rotating bowl spray The solution obtained is diluted to 2.8% with a mixture of propanol / butanol / EGME 10 / 18 / 72 (in mass %). It is applied by rotating bowl of 35 mm diameter on a glass plate, previously cleaned using a viscose cloth soaked in isopropyl alcohol and blown with compressed air. Example 8A: application on glass and implementation at low temperature. An anti-reflective deposit centered at 905 nm is obtained. The plate is then treated at 120°C for one hour. The optical properties are listed in Table 3. Example 8B: application on glass and implementation at high temperature. The plate obtained from Example 8A is then treated at 620°C for 15 minutes. The optical properties are shown in Table 2. Example 9: Preparation of ART4 composition: In Example 9, the preparation of the anti-reflective formulation is modified compared to Example 8. It aims to prepare an anti-reflective composition having a low surface energy for application, for example on Polycarbonate. The preparation is carried out with the following quantities of reagents (Table 8) and according to the following protocols. [Table 8] The preparation of condensed hydrolysates and colloidal solutions is similar to Example 1. Formulation of ART4 composition: In a 1 L flask, the MSG1 material is introduced. Then, at room temperature, SC1, EGME, butanol and propanol are added successively. The mixture is left stirring until the MSG1 is completely dissolved. Then, GPTS, MTMS and PFDTMS are added and stirred for 10 minutes. Finally, AcOH is added to the mixture. The mixture is then brought to 45°C and stirred for 24 hours. Aging is continued, without stirring, in a pot, for a further 72 hours. The reaction mixture is then evacuated to 400 mbar for 90 minutes. The contents are then transferred to a white polypropylene pot and stored for 10 days. The ES% is then checked and measured at 3.4%. • Application by electrostatic rotating bowl spray The resulting solution is diluted to 2.5% with a mixture of propanol / butanol / EGME 10 / 22 / 68 (in mass %). It is applied by rotating bowl on an extruded PC plate with a 50 mm bowl to target an anti-reflection around 905 nm. The plate is previously cleaned using a viscose cloth soaked in isopropyl alcohol and the plate is blown with compressed air. An atmospheric plasma treatment (gas = air) is then applied using a PlasmaTreat RD1004 type Plasma nozzle. An anti-reflective deposit centered at 905 nm is obtained. The plate is then treated at 120°C for one hour. The optical properties are listed in Table 2. Using a Kruss goniometer, a drop angle measurement is carried out on the surface of the resulting anti-reflective coating. A drop angle relative to water of 127° is measured. These characteristics give the anti-reflective coating low surface energy and good cleanability properties. Example 10: Preparation of the ARUV2 composition: In Example 10, the preparation of the UV anti-reflective formulation is modified compared to Example 7. It aims to prepare an anti-reflective composition for application in particular on PC or PMMA plastics for example, having a more pronounced hydrophobic character than Example 7. The preparation is carried out with the following quantities of reagents (Table 9 below) and according to the following protocols. [Table 9] Preparation of the MSG4 matrix (hydrolyzate-condensate): In a 500 mL flask, the following products are successively introduced: MTEOS and VTEOS. The mixture, while stirring, is thermostated for 5 min at 50°C. Then the Hydrochloric Acid HCl solution at pH 4.5 is added. Stirring is continued for 60 min and then the mixture is brought to 85°C for 14 h. The mixture is then brought to room temperature. 250 mL of NaCl saline solution is added to the mixture, then the diethyl ether solution is extracted and concentrated as in Example 2. An ES% of 89% is measured. Preparation of the SC4 matrix (colloidal suspension): In a 500 mL flask equipped with a condensation column, immersed in a bath at 25°C, ethanol, methanol, and distilled water are successively introduced. The mixture is thermostated while stirring at 60°C. Ammonia is then added and stirred at 60°C for 5 minutes. TEOS is then added and stirred at 0°C for 8 hours. VTEOS is then added and stirred for 12 hours. The flask is then equipped with a Vigreux column connected to a recovery flask filled with distilled water. Reflux is continued until the pH reaches a value of 6.2 + / - 0.5. The temperature is then allowed to drop back to 30°C and the MTEOS is added. The mixture is left stirring for 10 to 30°C. The ES% of the colloidal solution is then characterized and 5.01% is measured. Formulation of the ARUV2 composition: In a 1 L flask, the MSG4 material is introduced. Then, SC4, EGME, butanol and propanol are added successively at room temperature. The mixture is left stirring until the MSG4 is completely dissolved. GPTS and MTMS are then added and stirred for 10 minutes. Finally, AcOH is added to the mixture. The mixture is stirred and thermostated at 50°C for 2 hours, then at 30°C for a further 24 hours. The reaction medium then returns to room temperature. Finally, Omnirad 184 is added and stirred for 2 hours. The ES% is then checked and measured at 5.75%. Application of spray varnish on PC support • Application by electrostatic rotating bowl spray (Example no. 10) The ARUV2 varnish is diluted to bring its ES% to 2.7% with a mixture of EGME / Propanol / Butanol 5 / 22 / 73 solvents (in mass %). The support is a 2 mm thick extruded PC Vindulex polycarbonate plate prepared and positioned as in examples 1 and 2. The use of an electrostatic sprayer is also identical to examples 1 and 2. The application is carried out with a 50 mm bowl to obtain centering at 905 nm. After spraying, the coated PC plate is kept under the same environmental conditions for 2 minutes. The plate is then placed in an oven at 80°C for 3 minutes and then exposed under a Mercury type UV lamp (Bulb-H). A dose in the UVA of 3J / cm 2 is applied to the plate. The optical characteristics of the plate were then measured, as well as the homogeneity of the deposit. They are listed in Table 3. Example 11: Preparation of ARUV3 composition: In Example 11, the preparation of the anti-reflective formulation is modified compared to Examples 7 and 11. It aims to propose a solution for the production of sol-gel anti-reflective layers for the infrared range and plastic or PMMA films from reactive acrylate functionalized materials. The preparation is carried out from the MSG2 hydrolyzate-condensate and a new colloidal solution with the following quantities of reagents (Table 10) and according to the following protocols. [Table 10] Preparation of the SC5 matrix (colloidal suspension): In a 500 mL flask, immersed in a bath at 35°C, the colloidal solution MIBK-AC-21407 was introduced, and, with good stirring, the ethanol. TMPTA was then gradually added. The mixture was left stirring for 2 hours. The ES% was characterized and measured: 30.4%. Formulation of the ARUV3 composition: In a 1 L flask, the MSG2 material was introduced. EGME, butanol, propanol, and then SC5 were then added successively at room temperature. Stirring was continued until the MSG2 was completely dissolved. GPTS, MTMS, and AcOH were then added and stirring was continued for 10 minutes. The mixture was stirred and thermostated at 35°C for 24 hours, then Omnirad was added, and the reaction medium was stored at room temperature in a polypropylene pot for 5 days. The ES% was then characterized and found to be 9.08%. Application of spray varnish on PC support • Application by electrostatic rotating bowl spray (Example no. 11) The ARUV3 varnish is diluted to bring its dry extract to 2.7% with a mixture of EGME / Propanol / Butanol 12 / 30 / 58 solvents (in mass %). The support is a 375 μm thick PC Makrofol sheet from Covestro, fixedly deposited on two 2 mm thick PC Vindulex plates, themselves placed on a metal table. The PC sheet is electrically connected to ground. The application is carried out with a 35 mm bowl to obtain centering at 1550 nm. After spraying, the coated PC plate is kept under the same environmental conditions for 2 minutes. The plate is then placed in an oven at 80°C for 3 minutes, then exposed under a Mercury type UV lamp (Bulb-H). A dose in the UVA of 1 J / cm 2 is applied to the plate. The optical characteristics of the plate are then measured as well as the homogeneity of the deposit. They are listed in Table 3. Example 12 (comparative) The preparation of the ART7 formulation is based on the preparation of 2 sub-components (MSG7 and SC1) before their mixing. The condensate of the ART7 formulation is a tetraethoxysilane condensate (TEOS). Preparation of the ART7 anti-reflective composition The preparation of the MSG7 matrix and the ART7 composition is carried out with the quantities of reagents detailed in the following Table 11 and according to the following protocols. SC1 is carried out as in the application of the present invention. [Table 11] Preparation of MSG7 matrix (hydrolyzate-condensate): In a 500 mL flask, the following products are successively introduced: TEOS, EtOH. The mixture, while stirring, is thermostated for 5 min in a bath at 25°C. Then the previously mixed DI water and HCl are added. The heating bath is heated to 35°C and left stirring for 24 minutes, then the mixture is allowed to return to room temperature. The ES% is measured at 14.58%. Formulation of ART7 composition: In a 1 L flask, placed in a thermostatic bath at 25°C, the EGME is introduced, then successively with stirring the MTMS, the GPTS and AcOH. Then, after 5 minutes, the MSG7 material is added and 5 minutes after SC1. The bath temperature is brought to 35°C and stirred for 16°C and allowed to return to room temperature. The ES% is measured at 6.02%. Application of ART7 varnish by SPRAY: The ART7 varnish is diluted to bring its dry extract to 3% with a mixture of EGME / Propanol / Butanol 15 / 20 / 65 solvents (in mass %). The conditions are the same as in example 2. The optical characteristics of the treated extruded PC plate are shown in Table 3. With identical or substantially comparable dry extract, these characteristics are less good than those obtained in particular by spray with the formulations ART 1 (example 2) or ART3 (examples 8A and 8B) or ART 4 ​​(example 9). In particular, the homogeneity of the anti-reflective treatment, reflected by the standard deviation on the centering o% is 65 nm and the AHaze is 0.85%. Example 13 (comparative) The preparation of the ART6 formulation is based on the preparation of two sub-components (MSG6 and SC1) before mixing them. The condensate of the ART6 formulation has a tetraalkoxysilane / trialkoxysilane molar ratio greater than 50%. Preparation of the ART6 anti-reflective composition The preparation of the MSG6 matrix and the ART6 composition is carried out with the following quantities of reagents (Table 12) and according to the following protocols. SC1 is carried out as previously. [Table 12] Preparation of MSG6 matrix (hydrolyzate-condensate): In a 500 mL flask, the following products are successively introduced: TEOS, MTMS. The mixture, while stirring, is thermostated for 5 min in a bath at 25°C. The HCl solution at pH 3 is then added. The mixture is left to stir for 20 minutes and then the bath temperature is brought to 50°C for 5 hours. Stirring is then continued for 12 hours. for 48 hours. Distillation is carried out under vacuum (90 mbar) in a bath at 50°C. The ES% is measured at 43.0% Formulation of the ART6 composition: In a 1 L flask, placed in a thermostatic bath at 25°C, EGME and Butanol are introduced, then successively with stirring MTMS, GPTS and AcOH. Then after 5 minutes, MSG6 material is added and 5 minutes after SC1. The bath temperature is brought to 25°C and stirred for 12 hours, then 4 hours at 35°C and allowed to return to room temperature. The ES% is measured at 6.20%. Application of ART6 varnish by SPRAY: The ART6 varnish is diluted to bring its dry extract to 3% with a mixture of EGME / Propanol / Butanol 15 / 20 / 65 solvents (in mass %). The conditions are the same as in Example 2 of the application as filed. The optical characteristics of the treated extruded PC plate are shown in Table 3. With identical or substantially comparable dry extract, these characteristics are less good than those obtained in particular by spray with the formulations ART 1 (example 2) or ART3 (examples 8A and 8B) or ART 4 ​​(example 9). In particular, the homogeneity of the anti-reflective treatment, reflected by the standard deviation on the centering o% is 79 nm and the AHaze is 0.9%. Example 16 (Comparative) Synthesis of a MSG6B hydrolyzate-condensate We wish to prepare a variant of the ART6 type formulation but based on a more condensed hydrolyzate-condensate, according to a preparation method of the type of example 1 aimed at concentrating the hydrolyzate-condensate. The preparation is identical to that of MSG6. A vacuum distillation step (90 mbar) is added in a bath at 50°C. The ES% is measured at 52.0% but the material has gelled and cannot be used in a preparation of anti-reflective varnish according to the invention.< / t> < / t>

Claims

CLAIMS 1. Varnish composition for forming an anti-reflective varnish, the composition containing the following ingredients: (A) an alkoxysilane condensate, (B) a colloidal suspension of metal oxide nanoparticles functionalized with at least one alkoxysilane, (C) an alkoxysilane, and (D) at least two organic solvents with different boiling points, the alkoxysilane condensate (B) being obtained by hydrolysis and condensation, in an acidic hydroalcoholic medium, of at least one or more trialkoxysilane(s) (1) and, optionally, in addition, of at least one other silane chosen from tetraalkoxysilanes (2), dialkoxysilanes (3), bi-silanes (4) or one of their mixtures, the molar ratio [(2) and / or (3) and / or (4)] / (1) being less than 50%.

2. Composition according to claim 1, in which the alkoxysilane condensate (A) is obtained by hydrolysis and condensation, in an acidic hydroalcoholic medium, of at least one or more trialkoxysilane(s) (1) and at least one other silane chosen from tetraalkoxysilanes (2), dialkoxysilanes (3), bi-silanes (4) or one of their mixtures, the molar ratio [(2) and / or (3) and / or (4)] / (1) being between 0.5% and 50%, preferably between 1% and 20%, preferably between 2% and 15%.

3. Composition according to claim 1 or 2, in which the alkoxysilane condensate (A) is the reaction product in an acidic hydroalcoholic medium of one of the following silane mixtures: methyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane and dimethyldiethoxysilane; methyltrimethoxysilane and diisobutyldiethoxysilane; methyltriethoxysilane, tetraethoxysilane and 3-(glycidoxypropyl)methyldiethoxysilane; methyltriethoxysilane and methacryloxypropyltrimethoxysilane; methyltriethoxysilane and vinyltrimethoxysilane; 3-(glycidoxypropyl)methyldiethoxysilane and dimethyldiethoxysilane; 1,2-bis(trimethoxysilyl)ethane, methyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane and dimethyldiethoxysilane; methyltrimethoxysilane, methacryloxypropyltrimethoxysilane and dimethyldiethoxysilane; methyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, dimethyldiethoxysilane and methacryloxypropyltrimethoxysilane; tetraethoxysilane, phenyltrimethoxysilane and dimethyldiethoxysilane;3-glycidoxypropyltrimethoxysilane and tetraethoxysilane; methyltrimethoxysilane, tetraethoxysilane and phenyltrialkoxysilane; methyltriethoxysilane and vinyltriethoxysilane.; 4. Composition according to any one of the preceding claims, in which the alkoxysilane condensate (A) is a polysiloxane with a condensation rate of between 60 and 97.5%, in particular between 65 and 95%, in particular between 70 and 92%, more particularly between 75 and 90%, preferably between 77.5% and 87.5%.

5. Composition according to any one of the preceding claims, in which the suspension (B) comprises silica, preferably in a mass concentration of 1.5 to 65%, in particular between 3 and 50%, preferably between 5% and 45%, more preferably between 10 or 15 and 45%, or between 10 or 15 and 40% in an organic solvent or water, and / or a particle size, evaluated according to a dynamic light scattering method, of between 2 and 250 nm, in particular between 5 nm and 150 nm, in particular between 8 and 100 nm, more particularly between 10 and 100 nm, preferably between 12 and 80 nm.

6. Composition according to any one of the preceding claims, in which the alkoxysilane (C) comprises one or more tetraalkoxysilane(s), trialkoxysilane(s), dialkoxysilane(s) or a mixture of several alkoxysilanes chosen from tetraalkoxysilanes, trialkoxysilanes and dialkoxysilanes.

7. Composition according to any one of the preceding claims, wherein in (D) the at least two organic solvents comprise at least one solvent having a boiling point between 110°C and 140°C, and at least one solvent having a boiling point between 140°C and 190°C, said solvents having a boiling point difference greater than or equal to 20°C, in particular between 20 and 70°C.

8. A composition according to any preceding claim, wherein in (D) one solvent is ethylene glycol monoisopropyl ether or propylene glycol methyl ether acetate or 2-butoxyethanol or di(propylene glycol) dimethyl ether or ethyl-2-hexanol or a mixture of these products and the other solvent is 1-butanol or 1-methoxy-2-propanol or a mixture of these products.

9. Composition according to claim 6, in which the mass proportion of solvents having a boiling point of between 110 and 140°C, relative to the total mass of solvents, is between 7 and 40%, and the mass proportion of solvents having a boiling point of between 140°C and 190°C, relative to the total mass of solvents, is between 10% and 55%.

10. Composition according to claim 6, in which the mass proportion of solvents having a boiling point of between 110 and 140°C, relative to the total mass of solvents, is between 50 and 99%, and the mass proportion of solvents having a boiling point of between 140°C and 190°C, relative to the total mass of solvents, is between 2% and 50%.

11. Composition according to any one of the preceding claims, the composition having a dry extract of between 0.4% and 10%.

12. Composition according to any one of the preceding claims, in which the ratio of mass of dry matter from (A) to the mass of dry matter from of (B) is between 5% and 50%, preferably between 8% and 45%; and / or the ratio of dry matter from the alkoxysilane or the mixture of alkoxysilanes (C) to the dry matter from (A) is between 1% and 150%, preferably between 3 and 30%.

13. A method of forming an anti-reflective varnish on a transparent substrate (2), comprising applying by spraying, preferably by means of a sprayer (6) with a rotating bowl (8) and electrostatic charge, or by immersion, a varnish composition according to any one of claims 1 to 12, then drying the composition to form the varnish.

14. Method according to claim 13, wherein, for a spray application, the mass proportion of solvents having a boiling point between 110 and 140°C is between 7 and 40%, and the mass proportion of solvents having a boiling point between 140°C and 190°C is between 10 and 55%; for a dipping application, the mass proportion of solvents having a boiling point between 110 and 140°C is between 50 and 99%, and the mass proportion of solvents having a boiling point between 140°C and 190°C is between 2 and 50%.

15. Method according to claim 13 or 14, in which, for a spray application, the dry extract of the composition during its application is between 1 and 10%, in particular between 1.9 and 6%, preferably between 2.2 and 5%; for an immersion application, the dry extract of the composition during its application is between 2 and 10%, preferably between 2.5 and 8.5%, more preferably between 2.9 and 6.5%.

16. Transparent substrate covered on one side in whole or in part with a dried anti-reflective varnish obtained by the process according to any one of claims 13 to 15, or with the dried varnish resulting from the composition according to any one of claims 1 to 12.

17. Substrate according to claim 16, characterized in that it constitutes a protection device or an optical lens of a headlight, a LiDAR, a camera.

18. Substrate according to claim 16 or 17, characterized in that the substrate is made of polycarbonate, polymethyl methacrylate, or glass, in particular float glass.

19. Motor vehicle comprising at least one substrate according to any one of claims 16 to 18.

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