BE1024950B1 - Glass substrate coated with an anti-reflective layer - Google Patents

Abstract

The present invention relates to a coated glass substrate, in particular a glass substrate comprising an anti-reflective layer (AR) with improved opto-energetic performances and having good mechanical and chemical durability. The glass substrate according to the invention comprises a glass sheet provided with a porous AR layer which mainly comprises silicon oxide present in the form of (i) a sol-gel type matrix and (ii) particles. Advantageously, the AR layer further comprises aluminum oxide in an amount, expressed as Al 2 O 3, greater than or equal to 2.0% by weight and less than or equal to 5.0% by weight and in it also comprises at least 55% by weight of particles and at most 80% by weight of particles relative to the total weight of silicon oxide.

Description

(73) Holder (s):

AGO GLASS EUROPE

1170, BRUXELLES / WATERMAEL-BOITSFORT Belgium

ASAHI GLASS COMPANY 100-8405, TOKYO Japan

AGC FLAT GLASS NORTH AMERICA GA30022, ALPHARETTA GEORGIA United States (72) Inventor (s):

LECOLLEY François - AGC Glass Europe - R&D Center

6040 JUMET

Belgium

OUDARD Jean-François - AGC Glass Europe - R&D Center

6040 JUMET

Belgium (54) Glass substrate coated with an anti-reflective layer (57) The present invention relates to a coated glass substrate, in particular a glass substrate comprising an anti-reflective layer (AR) with improved opto-energy performance and having good mechanical and chemical durability. The glass substrate according to the invention comprises a glass sheet provided with a porous AR layer which mainly comprises silicon oxide present in the form (i) of a matrix of sol-gel type and (ii) of particles. Advantageously, the AR layer further comprises aluminum oxide in quantity, expressed in the form of Al2O3, greater than or equal to 2.0% by weight and less than or equal to 5.0% by weight and which it also comprises at least 55% by weight of particles and at most 80% by weight of particles relative to the total weight of silicon oxide.

Fig. i

BELGIAN INVENTION PATENT

FPS Economy, SMEs, Middle Classes & Energy

Publication number: 1024950 Filing number: 2011/0519

Intellectual Property Office

International Classification: C03C 17/00 C03C 17/34 G02B 1/11 Date of issue: 08/23/2018

The Minister of the Economy,

Having regard to the Paris Convention of March 20, 1883 for the Protection of Industrial Property;

Considering the law of March 28, 1984 on patents for invention, article 22, for patent applications introduced before September 22, 2014;

Given Title 1 “Patents for invention” of Book XI of the Code of Economic Law, article XI.24, for patent applications introduced from September 22, 2014;

Having regard to the Royal Decree of 2 December 1986 relating to the request, the issue and the maintenance in force of invention patents, article 28;

Considering the patent application received by the Intellectual Property Office on August 31, 2011.

Whereas for patent applications falling within the scope of Title 1, Book XI of the Code of Economic Law (hereinafter CDE), in accordance with article XI. 19, §4, paragraph 2, of the CDE, if the patent application has been the subject of a search report mentioning a lack of unity of invention within the meaning of the §ler of article XI.19 cited above and in the event that the applicant does not limit or file a divisional application in accordance with the results of the search report, the granted patent will be limited to the claims for which the search report has been drawn up.

Stopped :

First article. - It is issued to

AGC GLASS EUROPE, Chaussée de la Hulpe 166, 1170 BRUXELLES / WATERMAEL-BOITSFORT Belgium;

ASAHI GLASS COMPANY, Shin-Marunouchi Building 1-5-1, Chyioda-Ku, 100-8405 TOKYO Japan;

AGC FLAT GLASS NORTH AMERICA, 11175 Cicero Drive Suite 400, GA30022 ALPHARETTA GEORGIA United States;

represented by

LARANGE Françoise, Rue de l'Aurore 2, 6040, JUMET;

a Belgian invention patent with a duration of 20 years, subject to payment of the annual fees referred to in article XI.48, §1 of the Code of Economic Law, for: Glass substrate coated with an anti-reflective layer.

INVENTOR (S):

LECOLLEY François - AGC Glass Europe - R&D Center, Rue de l'Aurore 2, 6040, JUMET;

OUDARD Jean-François - AGC Glass Europe - R&D Center, Rue de l'Aurore 2, 6040, JUMET;

PRIORITY (S):

DIVISION:

divided from the basic application: filing date of the basic application:

Article 2. - This patent is granted without prior examination of the patentability of the invention, without guarantee of the merit of the invention or of the accuracy of the description thereof and at the risk and peril of the applicant (s) ( s).

Brussels, 08/23/2018, By special delegation:

BE 2011/0519

2011/0519

Glass substrate coated with an anti-reflective layer

The present invention relates to a coated glass substrate, in particular a glass substrate comprising an anti-reflective layer (AR) with opto-energetic performance improved in transmission and having good mechanical and chemical durability.

Anti-reflective layers are widely used to increase light and energy transmission and eliminate reflections from glass. Reducing the reflection of light on the surface of a glass substrate is desired for many applications such as display cases, frames, photovoltaic devices (e.g. solar cells), senes, etc. In particular, in the case of solar applications of photovoltaic type, it is obviously very advantageous to reduce the amount of radiation which is reflected by the venous substrate of a solar cell, thus increasing the amount of radiation which makes its way to the layer. active (for example, a photoelectric transfer film such as a semiconductor such as amorphous silicon, microcrystalline silicon or else a photoelectrically active layer chosen from CdTe, a copper-indium-gallium-selenium alloy, the concentration of indium and gallium which can vary from pure copper and indium selenide to pure copper and gallium selenide, or a copper-indium-selenium alloy, these alloys being known to those skilled in the art under the acronym CIGS or CIS .

In the case of anti-reflective layers intended to reduce or eliminate reflections from glass, the most commonly used material is silica or silicon oxide, in the form of a monolayer or stack. In particular, porous silicon monolayers give good performance in terms of anti-reflective properties. In general, the higher the porosity, the lower the refractive index of the coating. Thus, it has been shown that by acquiring sufficient porosity,

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2011/0519 silica coatings with refractive indices from 1.2 to 1.3 can be produced. As an indication, a layer of non-porous (dense) silica typically has a refractive index of the order of 1.45.

Such porous layers are typically obtained by introducing a pore-forming agent into the precursor intended for the deposition of said layer. This blowing agent can be organic in nature, its subsequent combustion then creates the pores in the layer. It can also be mineral in nature, in the form of particles, and therefore remains in the layer even after a heat treatment step. In particular, it has been shown that it is possible to generate a porous layer of silica by combining colloidal silica particles and silica originating from a silane precursor in a sol-gel type process.

However, such anti-reflective layers of porous silica have drawbacks. Indeed, increasing the porosity of a coating in general leads to a decrease in their mechanical and chemical resistance, which is why there are problems of durability to the external environment, of degradation due to the effects of abrasion during , for example, cleaning coatings.

To reduce this phenomenon of reduction in the mechanical and / or chemical resistance of the coating of porous silica, it can be doped, for example via the incorporation of elements such as Al, Zr, B, Sn or Zn in the form of oxide. In particular, aluminum is known to give good results in this context. Unfortunately, due to the significantly higher refractive index of aluminum oxide compared to silica (of the order of 1.67 in a dense layer) and even that of glass (1.51), this incorporation results in an increase in the refractive index of the doped layer and a decrease in its antireflection performance.

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The invention particularly aims to overcome these latter drawbacks by solving the technical problem, namely to provide a porous anti-reflective layer which has sufficient mechanical and chemical resistance, while not adversely affecting the light transmission through of the glass substrate that it covers, or even improving it.

The invention, in at least one of its embodiments, also aims to provide a solution to the disadvantages of the prior art which is simple, rapid and economical.

Another objective of the invention, in at least one of its embodiments, is to implement a method of manufacturing a glass substrate comprising an anti-reflective layer, said method being easy and flexible.

In accordance with a particular embodiment, the invention relates to a glass substrate comprising a glass sheet provided on at least part of at least one of its faces with a porous anti-reflective layer, said layer mainly comprising silicon oxide, SiO ₂ present in the form of (i) a sol-gel type matrix and (ii) of particles.

According to the invention, the porous anti-reflective layer further comprises aluminum oxide in quantity, expressed in the form of A1 ₂ O ₃ , greater than or equal to 2.0% by weight, preferably greater than or equal to 2, 5% and less than or equal to 5.0% by weight, preferably less than or equal to 4.1% by weight and in that it also comprises at least 55% by weight of particles, preferably at least 60% by weight of particles and at most 80% by weight of particles, preferably at most 75% by weight of particles, more preferably at most 70% by

BE 2011/0519

2011/0519 weight of particles, most preferably at most 65% by weight of particles relative to the total weight of silicon oxide.

Thus, the invention is based on a completely new and inventive approach because it makes it possible to solve the drawbacks of the prior art and to solve the technical problem posed. The inventors have indeed demonstrated that it was possible, by combining

- a matrix of sol-gel type of silicon oxide;

- particles of silicon oxide in a very precise quantity; and

- aluminum oxide in a very precise quantity also;

to obtain an anti-reflective layer having good mechanical and chemical resistance but above all showing improved anti-reflective properties. This result is very surprising in that, as mentioned previously, aluminum oxide (or alumina) intrinsically has a higher refractive index than silica. In addition, the inventors have determined that, surprisingly, an anti-reflective layer comprising at least 55% by weight of particles, preferably at least 60% by weight of particles and at most 80% by weight of particles, preferably at most 75% by weight of particles, more preferably at most 70% by weight of particles, most preferably at most 65% by weight of particles, relative to the total weight of silicon oxide makes it possible to obtain a compromise between, on the one hand , the improvement of the antireflection properties of the layer and, on the other hand, the mechanical resistance of the layer. Furthermore, the inventors have also determined that, surprisingly, the addition of a large amount of aluminum oxide, expressed as Al ₂ O ₃ , greater than or equal to

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2.0% by weight, preferably greater than or equal to 2.5% and less than or equal to 5.0%% by weight, preferably less than or equal to 4.1% by weight, makes it possible to improve the antireflection properties of the layer while keeping the amount of colloidal silica constant, this improvement in the optical performance of the anti-reflective layer not being accompanied by a deterioration in the mechanical durability of the anti-reflective layer.

According to a preferred embodiment, the glass substrate according to the invention comprises, consists of, consists essentially of a glass sheet provided on at least part of at least one of its faces with a porous anti-reflective layer, said layer mainly comprising silicon oxide, SiO ₂ present in the form (i) of a solgel type matrix and (ii) of particles, such that the porous anti-reflective layer also comprises aluminum oxide in amount, expressed as A1 ₂ O ₃ , ranging from 2.0% to 5.0%, preferably ranging from 2.0% to 4.1% by weight, more preferably ranging from 2.5% to 4.1 % by weight, and such that it also comprises between 55% and 80% by weight of particles, 60% and 75% by weight of particles, preferably between 60% and 70% by weight of particles, most preferably between 60% and 65% by weight of particles, relative to the total weight of silicon oxide.

According to the invention, the glass substrate comprises a glass sheet. The glass according to the invention can belong to various categories. The glass can thus be a soda-lime type glass, a boron glass, a glass comprising one or more additives distributed homogeneously in its mass, such as, for example, at least one inorganic dye, an oxidizing compound, a viscosity regulating agent and / or an agent facilitating fusion. Preferably, the glass of the invention is of the soda-lime type. The glass of the invention can be a float glass, a drawn glass or a glass

BE 2011/0519

2011/0519 printed or textured for example by a roller or by acid or alkaline attack. It can be clear, extra-clear, sandblasted and / or matt, preferably the glass is an extra-clear glass. The expression soda-lime glass is used here in its broad sense and relates to any glass which contains the following basic components (expressed as percentages by total weight of glass):

SiO ₂ 60 to 75% Na ₂ O 10 to 20% CaO 0 to 16% κ, ο 0 to 10% MgO 0 to 10% A1 ₂ O ₃ 0 to 5% BaO 0 to 2% BaO + CaO + MgO 10 to 20% K ₂ O + Na ₂ O 10 to 20%.

It also designates any glass comprising the above basic components which may also comprise one or more additives.

The glass sheet of the invention may have a thickness varying, for example, from 2 to 10 mm.

According to a preferred embodiment, in particular in the case of solar applications, the glass sheet is a printed or textured glass sheet, that is to say one which has a macroscopic relief, for example in the form of patterns of the pyramid or cone type, the patterns can be convex (protruding from the general plane of the printed face) or concave (recessed in the mass of the glass). Preferably, the glass sheet is printed or textured on at least one of its faces. Such a glass substrate, both textured and coated with an anti-reflective layer, combines the light trapping effect and the anti-reflective effect.

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According to this preferred embodiment, the face of the glass substrate which is coated with the porous layer is, advantageously, that which is not textured.

Preferably, in the case of solar applications, the glass sheet is made of an extra-clear glass. By extra-clear glass is meant a glass whose composition comprises less than 0.06% by weight of total iron, expressed in the form of Fe ₂ O ₃ , and preferably less than 0.02% by weight of total iron , expressed as Fe ₂ O ₃ .

According to the invention, and in the absence of precision, by layer is understood either a single layer (monolayer) or a superposition of strata (multilayer). According to an advantageous embodiment, the layer may be in the form of a superposition of strata. We may prefer in particular to manufacture increasingly porous strata away from the carrier substrate, and / or strata of different thicknesses, this in order to further improve the anti-reflective effect.

According to the invention, the glass substrate is coated with the porous anti-reflective layer on at least part of at least one of its faces. The layer can extend continuously over substantially the entire surface of the substrate, for example over more than 90% of its surface, preferably over more than 95% of its surface. Alternatively, the layer may partially cover the surface of the substrate. The substrate can also be coated on each of its faces, partially or completely with said layer.

According to the invention, the porous anti-reflective layer mainly comprises silicon oxide present in the form of (i) a matrix of sol-gel type and (ii) of particles.

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By a layer mainly comprising silicon oxide, it is meant that the layer according to the invention consists of silicon oxide, SiO ₂ at a rate of at least 80% by weight relative to the total weight of the layer , and preferably at least 90% by weight.

According to the invention, the SiO ₂ matrix is an essentially continuous and amorphous solid phase. It is obtained by the well-known sol-gel process. This matrix will constitute the “binder” of the silica particles also present in the layer. It is the association of the matrix resulting from a sol-gel process with the particles (pore-forming agent) which will generate the porous structure of the layer of the invention.

The particles of the invention can be solid or hollow. They can, for example, be of almost spherical or elongated shape (in the form of sticks, for example). Preferably, the particles have an elongated shape, more preferably have a rod shape, the inventors having determined that this type of particles makes it possible to obtain a porosity of up to 50% by volume of trapped air and therefore the using this type of particle ensures an increased anti-reflective effect. In comparison, a random stack of spherical particles makes it possible to obtain a maximum porosity of around 36% and a compact hexagonal stack of these same spherical particles a maximum porosity of around 24%.

According to a preferred embodiment of the invention, the particles are nanoparticles.

Preferably, the particles of the invention have a size which is not less than 2 nm and, preferably, which is not less than 5 nm. In addition, the particles have a size which is not more than 500 nm and preferably which is not more than 250 nm. By size is meant

BE 2011 / 05X9

2011/0519 designate the largest dimension of the particles (the diameter for a sphere, the length for an elongated particle, etc.).

The layer according to the invention may include particles of different or similar sizes and / or shapes, preferably said particles forming chains.

According to a preferred embodiment of the invention, the porous anti-reflective layer has a thickness which is between 50 nm and 300 nm, preferably between 70 nm and 250 nm, more preferably between 80 nm and 200 nm, the more preferably between 80 nm and 150 nm. The inventors have determined that, surprisingly, such thicknesses of anti-reflective layer make it possible to obtain improved opto-energy performance, particularly in the field of wavelengths ranging from 400 to 1100 nm.

According to another preferred embodiment, a substantially non-porous sublayer is interposed between the glass sheet and the anti-reflective layer. By substantially non-porous sublayer is meant a so-called "dense" layer, in other words a sublayer having a higher density than the porous anti-reflective layer. The sublayer of the invention can, for example, act as a barrier to alkalis.

According to this embodiment, the sublayer preferably comprises at least one compound chosen from zirconium oxide, titanium oxide, aluminum oxide, silicon oxide and silicon oxynitride. Preferably, the sublayer mainly comprises a compound chosen from zirconium oxide, titanium oxide, aluminum oxide, silicon oxide and silicon oxynitride. More preferably, the sub-layer mainly comprises silicon oxide. By a sub-layer mainly comprising one of the compounds from the list above,

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2011/0519 means a sub-layer consisting of said compound in an amount of at least 80% by weight relative to the total weight of the layer, and preferably at least 90% by weight. Preferably, the sublayer comprises a compound chosen from zirconium oxide, titanium oxide, aluminum oxide, silicon oxide and silicon oxynitride, said compound being associated with a compound additional selected from zirconium oxide, titanium oxide, aluminum oxide, silicon oxide. The additional oxide or oxides may represent at most 10% by weight of the whole and preferably at most 5%. Most preferably, the sublayer is based on silicon oxide, said silicon oxide being associated with at least one other oxide selected from the group comprising zirconium oxide, titanium oxide, oxide d 'aluminum. The respective proportions of silicon oxide and of the other oxides being such that the value of the refractive index of the undercoat is between the values of the refractive index of the glass sheet and the refractive index of the porous anti-reflective layer, said refractive indices being measured at a wavelength of 550 nm. Preferably, the sub-layer has a thickness which is between 5 nm and 200 nm, preferably between 50 nm and 150 nm.

The undercoat according to the invention can also be deposited by the sol-gel method but also by the vapor phase deposition (CVD) method or by sputtering. Preferably, the undercoat is deposited by sol-gel method, the inventors having determined that surprisingly an undercoat deposited by sol-gel method allows to obtain a better adhesion of the porous anti-reflective layer, more particularly when said undercoat is subjected, after application of the sol-gel solution at the origin of said undercoat on the glass sheet and preferably before application of the sol-gel solution at the origin of the anti-reflective layer porous, to a heat treatment less than or equal to a temperature of 200 ° C. Furthermore, the inventors have determined that in a manner

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2011/0519 surprisingly an undercoat deposited by sol-gel method although less dense has a sufficient alkali barrier property.

The glass substrate according to the invention may also comprise an overlay, deposited on the anti-reflective layer. Such an overcoat can, for example, further reinforce the chemical durability of the anti-reflective layer in the case of applications outdoors or in a humid environment, for example.

Another object of the invention relates to the method of manufacturing the glass substrate comprising an anti-reflective layer according to the invention. Said method is such that it comprises the steps of forming the following anti-reflective layer, in order:

a) the preparation of a "sol" of a silicon-based precursor in a particularly aqueous and / or alcoholic solvent at acid pH;

b) adding an aluminum-based precursor to the soil prepared in step (a);

c) mixing the "soil" with silica particles;

d) depositing on a glass sheet the soil / particle mixture; and

e) the heat treatment of the coated glass sheet, advantageously said treatment corresponds to the tempering treatment of the glass sheet when thermal tempering of said sheet is necessary;

the first two steps can be carried out simultaneously or alternatively. The silicon-based precursor is preferably a hydrolyzable compound such as a silicon alkoxide. The precursor based

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2011/0519 of aluminum can be chosen in particular from alkoxides, nitrate or acetylacetonate.

Advantageously, the silica particles are added to the soil in the form of a dispersion in a liquid (for example, water).

The deposition of the soil / particles mixture on the substrate can be carried out by spraying, by immersion and drawing from silica sol {dip coating}, by centrifugation {spin coating}, by casting {flow-coating} or by roller {rollcoating }.

The process may preferably comprise a step of drying or removing the solvent (s), at a temperature below about 200 ° C, preferably below about 150 ° C, occurring just after the deposition step and before the heat treatment of the coated glass sheet of step (e)).

According to an advantageous implementation, the method of manufacturing the glass substrate according to the invention is such that it comprises, before depositing the anti-reflective layer, the following steps, in order:

1) the preparation of a "sol" of a silicon-based precursor in a particularly aqueous and / or alcoholic solvent at acid pH;

2) adding a precursor based on aluminum and / or zirconium in the soil prepared in step (1);

3) the deposition on a glass sheet of the mixture of the solution resulting from steps 1) and 2) by spraying, by immersion and drawing from the silica solution (dip coating), by centrifugation (spin coating), by casting (flow-coating) or by roll (roll coating); and

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4) the heat treatment for drying or removing the solvent (s) from the coated glass sheet at a temperature less than or equal to 200 ° C., preferably less than or equal to 150 ° C., the first two steps can be carried out simultaneously or well successively. The silicon-based precursor is preferably a hydrolyzable compound such as a silicon alkoxide. The aluminum and / or zirconium precursor can be chosen in particular from alkoxides, nitrate or acetylacetonate.

The heat treatment of the glass sheet coated with all of its layers can be carried out at temperatures of the order of 300 ° C to 720 ° C, preferably of the order of 300 ° C to 680 ° C, for example of 'order from 300 ° C to 650 ° C or for example from 300 ° C to 550 ° C and allows the condensation / formation of the porous layer based on silica and alumina.

The glass substrate coated according to the invention can also subsequently be heat treated for tempering or for bending. Advantageously, the last step of the process of the invention (condensation / formation of the layer) can also correspond to a heat treatment with a view to quenching or bending the substrate, if it is carried out under conditions suitable respectively for these two operations (typically at temperatures which are not lower than 500 ° C and even of the order of 600-700 ° C). The porous layer according to the invention can indeed withstand such heat treatment without significant alteration of its opto-energetic properties.

Glass substrates according to the invention can have various applications. These substrates can be used as glazing for aquariums, display cases (interior or exterior), greenhouses, frames or tables, etc. They can also be used

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2011/0519 in areas such as aeronautical, maritime, land transport (eg windshields), for the building industry, or for household appliances. Very advantageously, they can be used in applications of the solar type. These include solar panels, in particular thermal solar collectors or photovoltaic cells.

Thus, the invention also relates to a solar cell comprising the glass substrate coated with an anti-reflective layer according to the invention.

Other characteristics and advantages of the invention will appear more clearly on reading the following description of preferred embodiments, given by way of simple illustrative and nonlimiting examples, and of the appended figures, among which:

Figure 1 shows a cross section of a glass substrate according to the invention (1) comprising a glass sheet (10) and a porous anti-reflective layer (12).

FIG. 2 represents a cross section of a glass substrate according to the invention (1) comprising a glass sheet (10), an under layer (11) and a porous anti-reflective layer (12).

FIG. 3 represents a graph showing the transmission profiles of a glass substrate according to the invention (B), of a glass substrate coated with a porous anti-reflective layer not in accordance with the invention containing no oxide aluminum (C), a glass substrate coated with a porous anti-reflective layer not in accordance with the invention containing an amount of aluminum oxide of 6.0% by weight (D) and a Uncoated glass substrate of the same kind (A).

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FIG. 4 represents a graph showing the evolution of the gain in transmission of a glass substrate according to the invention as a function of the amount of alumina present in the anti-reflective layer of said glass substrate relative to an uncoated glass substrate of the same nature and this for a porous anti-reflective layer in which the quantity of silica particles constitutes 60% by weight of the total silica.

FIG. 5 represents a graph showing the evolution of the gain in transmission of a glass substrate according to the invention as a function of the percentage by weight of colloidal silica and this at a constant amount of alumina (2.5% by weight) in the anti-reflective layer of said glass substrate with respect to an uncoated glass substrate of the same nature.

The following examples illustrate the invention without intending to limit its coverage in any way.

Examples

- Formulation for the undercoat: A solution was prepared by mixing nitric acid (0.090 kg) with distilled water (11.850 kg) and ethanol (80.180 kg). Tetraethylorthosilicate (7.670 kg) was added to this mixture, then the solution was allowed to react for one hour at room temperature with stirring. Then add zirconium acetylacetonate (0.180 kg). The solution was stirred for an additional 30 minutes.

- Mixture 1 (comparative): A formulation is prepared by mixing ethanol (53.230 kg), butanol (24,000 kg), 4-hydroxy-4-methylpentan-2-one (16,000 kg). To this mixture was added nitric acid (0.015 kg) and distilled water (1.980 kg). Then, tetraethylorthosilicate (TEOS - 1.280 kg) was added and the solution was allowed to react with stirring for one hour at room temperature to allow

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2011/0519 hydrolysis of the silicon precursor. After this stirring period, particles of silica dispersed in water (Snowtex OUP colloidal silica from Nissan Chemical Industries Ltd. - 3.430 kg) were finally added to the "soil" obtained in the previous step. Snowtex colloidal silica

OUP consists of elongated particles of silica having characteristic dimensions of the order of 9-15 nm and 40-100 nm and forming chains of particles linked together.

This formulation corresponds to an amount of silica particles of 59% by weight of total silica.

- Mixture 2 (comparative): A formulation is prepared by mixing ethanol (52.920 kg), butanol (24,000 kg), 4-hydroxy-4-methylpentan-2-one (16,000 kg). To this mixture was added nitric acid (0.015 kg) and distilled water (1.930 kg). Then, tetraethylorthosilicate (TEOS - 1.250 kg) was added and the solution was left to react with stirring for one hour at room temperature in order to allow the hydrolysis of the silicon-based precursor. Aluminum acetyiacetonate, Al (acac) 3 (0.360 kg) was then added and the solution was again stirred for an additional 30 minutes. After this stirring period, dispersed silica particles in water (Snowtex OUP colloidal silica from Nissan Chemical Industries Ltd. 3,490 kg) were finally added to the "soil" obtained in the previous step. Colloidal silica Snowtex OUP consists of elongated particles of silica having characteristic dimensions of the order of 9-15 nm and 40100 nm and forming chains of particles linked together.

This formulation corresponds to an amount of silica particles of 60% by weight of total silica and to an amount of aluminum oxide, expressed in the form of A1 ₂ O ₃ , of 6.0% by weight.

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- Mixture 3 (according to the invention): A formulation was prepared by mixing ethanol (53.040 kg), butanol (24,000 kg), 4hydroxy-4-methyl-pentan-2-one (16,000 kg) . To this mixture was added nitric acid (0.0150 kg) and distilled water (1.930 kg). Then, tetraethylorthosilicate (TEOS, 1.250 kg) was added and then the solution was allowed to react with stirring for one hour at room temperature to obtain a "sol". Aluminum acetylacetonate, Al (acac) ₃ (0.240 kg) was then added and the solution was again stirred for an additional 30 minutes. After that, Snowtex OUP colloidal silica (3,490 kg) from Nissan Chemical Industries Ltd. was finally added.

This formulation corresponds to an amount of silica particles of 60.0% by weight of total silica and to an amount of aluminum oxide, expressed in the form of Al ₂ O ₃ , of 4.0% by weight.

- Deposit on the glass: The formulation for the undercoat was deposited on one side of three sheets of extra-clear glass 10 cm x 10 cm by a "dip coating" process (immersion then drawing). The substrates thus obtained were dried in an oven at 120 ° C for 10 minutes. In a second step, the mixture 1, 2 or 3 was deposited on one of the substrates obtained, also by a “dip coating” process under identical experimental conditions for each. The heat treatment of the final glass sheet / undercoat / layer assembly was carried out during a thermal tempering process of the glass, carried out under conventional conditions (680 ° C. for 180 seconds).

- Optical properties: The optical properties of glass substrates coated from mixtures 1, 2 and 3 (respectively, substrate 1, 2 and 3) are represented in the graph in Figure 3, representing the transmission T between 300 and 1200 nm ( curve (C) for the substrate 1 curve (D) for the

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2011/0519 substrate 2 and curve (B) for substrate 3). They are compared to those of an identical glass substrate, but not coated (reference, curve (A)). This optical properties are measured according to ISO 9050: 2003.

There is an increase of 2.2% in light transmission over the 300-1100 nm interval for the substrate obtained with mixture 1 compared to the reference.

There is an increase of 2.6% in light transmission over the 300-1100 nm range for the substrate obtained with mixture 2 compared to the reference.

There is an increase of 2.5% in light transmission over the interval 300-1100 nm for the glass substrate according to the invention produced with the mixture 3 compared to the reference.

Consequently, an increase in the performance of the anti-reflective layer according to the invention (increase in transmission by 0.3%) is obtained by combining alumina with a sol-gel matrix and silica particles, in given quantities. Such a gain is really significant, in particular in the field of solar applications where the slightest increase in light transmission can lead to a very significant increase in efficiency.

In addition, the glass substrates obtained from mixtures 1, 2 and 3 were subjected to tests intended to assess their chemical and mechanical durability. In particular, the maintenance of their opto-energetic performance during tests under severe conditions has been verified. The results obtained are shown in the table below.

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Substrate 1 (comparative) Substrate 2 (comparative) Substrate 3 Initial gain in transmission (before test) 2.2% 2.6% 2.5% Gain in transmission after test Abrasion test (500 cycles) (standard EN 1096-2) 1.4% 1.1% 1.4% Humidity test (1000h) (standard IEC 61215) 2.0% 2.3% Pressure test (9h) 1.8% - 2.0% Thermal cycles (1500h) (IEC61215 standard) 1.8% 2.5% Salt test (4 days) (IEC1701 standard) 2.1% - 2.4% Saline test (21 days) (standard EN1096-2) 2.1% - 2.2%

The improvement in the opto-energy performance of the substrate according to the invention (substrate 3) is therefore not accompanied by a deterioration in the mechanical or chemical durability of the anti-reflective layer. Overall, the chemical and mechanical durability properties of the layer

BE 2011/0519

2011/0519 according to the invention are similar to those of the anti-reflective layer of the comparative example (substrate 1) for all the conventional tests carried out. In addition, the comparison of the gain in transmission before and after abrasion shows the advantage of limiting the amount of aluminum oxide in the porous antireflective layer, the reduction in the gain in transmission after abrasion being greater for the substrate 2, not according to the invention, comprising an amount of aluminum oxide expressed in the form of A1 ₂ O ₃ , of 6.0% by weight than for the substrate 3 according to the invention, said substrate 3 comprising an amount of aluminum oxide, expressed as A1 ₂ O ₃ , of 4.1% by weight. This effect is exemplified in FIG. 4 which shows the evolution of the gain in transmission of the porous anti-reflective layer before and after abrasion, as a function of the amount of aluminum oxide present in the porous anti-reflective layer and this for a porous antireflective layer in which the quantity of silica particles constitutes 60% by weight of the total silica. It is observed that the best compromise between, on the one hand, the gain in transmission and, on the other hand, the abrasion resistance, is obtained for quantities of aluminum oxide, expressed in the form of A1 ₂ O ₃ , ranging from 2.0% to 5.0% by weight, preferably ranging from 2.0% to 4.1% by weight, more preferably from 2.5% to 4.1% by weight.

Furthermore, the comparison of the gain in transmission before abrasion shows the advantage of adding aluminum oxide to the porous anti-reflective layer, the increase in the gain in transmission before abrasion being greater for the substrate 3. according to the invention as for the substrate 1, not according to the invention, not comprising aluminum oxide.

FIG. 5 shows the evolution of the gain in transmission of the porous anti-reflective layer before and after abrasion, as a function of the amount of colloidal silica present in the layer and this for a layer

BE 2011/0519

2011/0519 porous anti-reflective containing an amount of aluminum oxide, expressed in the form of A, ₂ O ₃ equal to 2.5% by weight. It is observed that the best compromise between, on the one hand, the gain in transmission and, on the other hand, the abrasion resistance is obtained for quantities of silica particles comprised 55% and 80% by weight of particles, preferably between 60% and 75% by weight of particles, more preferably between 60% and 70% by weight of particles, most preferably between 60% and 65% by weight of particles, relative to the total weight of silicon oxide.

BE 2011/0519

2011/0519

Claims (16)

1. Glass substrate (1) comprising a glass sheet (10) provided on at least part of at least one of its faces with a porous antireflective layer (12), said layer (12) mainly comprising oxide silicon, SiO ₂ present in the form of (i) a matrix of the sol5 gel type and (ii) of particles; characterized in that said layer (12) further comprises aluminum oxide in quantity, expressed in the form of A1 ₂ O ₃ , greater than or equal to 2.0% by weight, preferably greater than or equal to 2.5 % and less than or equal to 5.0% by weight, preferably less than or equal to 4.1% by weight And in that it also comprises at least 55% by weight of particles, preferably at least 60% by weight of particles and at most 80% by weight of particles, preferably at most 75% by weight of particles, more preferably at plus 70% by weight of particles, most preferably at most 65% by weight of particles, relative to the weight 15 total silicon oxide. 2. Glass substrate (1) according to the preceding claim, characterized in that the porous anti-reflective layer (12) comprises aluminum oxide, expressed in the form of A1 ₂ O ₃ , ranging from 2.0% to 5.0%, preferably from 2.0% to 4.1%, more preferably from 2.5% to 4.1% 20 by weight. 3. Glass substrate (1) according to any one of the preceding claims, characterized in that the layer (12) comprises between 55% and 80% by weight of particles relative to the total weight of silicon oxide, preferably between 60% and 75% by weight of the particles more Preferably between 60% and 70% by weight of particles, the most BE 2011/0519 2011/0519 preferably between 60% and 65% by weight of particles, relative to the total weight of silicon oxide. 4. Glass substrate (1) according to any one of the preceding claims, characterized in that the particles have an elongated shape, preferably have a shape of sticks. 5. Glass substrate (1) according to any one of the preceding claims, characterized in that the particles have a size which is between 2 and 500 nm. 6. Glass substrate (1) according to any one of the preceding claims, characterized in that the silica particles form chains. 7. Glass substrate (1) according to any one of the preceding claims, characterized in that the anti-reflective layer (12) has a thickness which is between 50 and 300 nm. preferably between 70 nm and 250 nm, more preferably between 80 nm and 200 nm, most preferably between 80 nm and 150 nm. 8. Glass substrate (1) according to any one of the preceding claims, characterized in that a sub-layer (11) substantially non-porous is interposed between said glass sheet (10) and said anti-reflective layer (12 ). 9. Glass substrate (1) according to the preceding claim, characterized in that the sublayer (11) comprises at least one compound chosen from zirconium oxide, titanium oxide, alumina oxide, l oxide and silicon oxynitride. 10. Glass substrate (1) according to the preceding claim, characterized in that the sub-layer (11) mainly comprises a BE 2011/0519 2011/0519 compound chosen from zirconium oxide, titanium oxide, alumina oxide, silicon oxide and silicon oxynitride, preferably silicon oxide. 11. Glass substrate (1) according to any one of claims 5 to 10, characterized in that the sublayer (11) has a thickness which is between 5 and 200 nm. 12. Glass substrate (1) according to any one of the preceding claims, characterized in that the glass sheet (10) is in a glass sheet of soda-lime type, preferably in a sheet of 10 extra clear glass. 13. A method of manufacturing the glass substrate (1) according to any one of the preceding claims, characterized in that said method is such that it comprises the steps of forming the following anti-reflective layer (12), in order: a) the preparation of a "sol" of a silicon-based precursor in a particularly aqueous and / or alcoholic solvent at acid pH b) adding an aluminum-based precursor to the soil prepared in step (a); c) mixing the "soil" with silica particles; d) depositing on a glass sheet (10) the soil / particle mixture; and e) heat treatment of the coated glass sheet (10), the first two stages can be carried out simultaneously or alternatively BE 2011/0519 2011/0519 14. The manufacturing method according to claim 13, characterized in that it includes the following steps, in order: 1. the preparation of a "sol" of a silicon-based precursor in 5, in particular an aqueous and / or alcoholic solvent at an acid pH; 2. adding a precursor based on aluminum and / or zirconium in the soil prepared in step (1); 3. depositing on a glass sheet (10) the mixture of the solution resulting from steps 1 and 2 by spraying, by immersion and 10 draw from the silica solution (dip coating), by centrifugation (spin coating), by casting (flow-coating) or by roller (roll coating); and 4. the heat treatment for drying or removing the solvent (s) from the coated glass sheet (10) at a temperature 15 less than or equal to 200 ° C. preferably less than or equal to 150 ° C, the first two steps can be carried out simultaneously or alternatively 15. Use of the glass substrate (1) according to any one of 20 preceding claims in applications of the solar type, in particular solar panels, solar thermal collectors or photovoltaic cells. BE 2011/0519 2011/0519