Glazing provided with a stack of thin layers for solar protection and/or heat insulation

Description of the invention

The present invention relates to a solar control and / or thermal insulation glazing which comprises at least one transparent substrate provided with an array of layers. A transparent substrate, especially made of a rigid inorganic material such as glass (or an organic material such as a rigid or flexible polymeric substrate), is covered with a thin layer system comprising at least one layer retaining a metallic type capable of being affected by solar radiation and / or long-wavelength infrared radiation.

The glazing according to the invention may be used for thermal insulation and / or sun protection. This glazing is intended for equipping both buildings and vehicles, in particular to reduce air conditioning loads and / or to reduce excessive overheating caused by an increasing degree of glazed surfaces in passenger compartments.

A known type of multi-layer system for imparting such properties to substrates consists of at least one metallic layer, such as a silver layer, which is sandwiched between two coatings of a metal oxide-type dielectric material. This arrangement is typically obtained by successive deposition steps performed using a vacuum technique such as sputtering, optionally assisted by a magnetic field. It is also possible to provide two very thin metal layers on each side with silver layers, the underlying layer acting as a binding layer for nucleation and the overlay layer as a protective or sacrificial layer, so as to prevent degradation of the silver if the oxide layer is on its top is deposited by sputtering in the presence of oxygen.

Systems of this type with one or two primary silver layers are known from EP-O 611 213, EP-O 678 484 and EP-O 638 528.

EP-O 847 965 also describes a system consisting of two silver layers, designed so that it can undergo heat treatment of the bending or hardening type without any substantial optical change, thanks to the use of an oxygen barrier layer of the silicon nitride type and a layer for stabilizing the silver layer.

Finally, a system consisting of two silver layers of very different thicknesses is known from EP-O 844 219, making it possible to obtain a glazing with a solar factor lowered to at least 32% (the solar factor SF is the ratio of the total energy entering the room through considered solar glazing).

Usually, but especially in the field of double glazing of buildings, it is advantageous to be able to select the level of light transmission of the glazing within a certain range without each time adequately reconfiguring the thin-layer system.

Solutions to achieve this goal have already been proposed: French patent FR-2 751 666 proposes to insert, between the glass and the first dielectric layer, an absorbent layer based on iron oxide. In French Patent FR-2 708 262 it is proposed to insert a layer of a titanium nitride type absorbent in contact with and above the silver layer. However, these solutions in both cases have a drawback if the thin layer system is subject to a heat treatment of the annealing, bending or quenching type: the absorbent layer will be optically significantly changed and / or will cause the multi-layer system to completely change optically.

This is because if the absorbent layer is in contact with glass or silver, it will, when exposed to heat, tend to oxidize, deteriorate or cause adjacent layers to deteriorate in a more or less controlled manner. Thus, when the absorbent layer is in direct contact with the silver layer, it tends to destabilize it by oxidation. If it is in contact with the glass, the layer will be modified by diffusion of alkali metal ions from the glass.

The object of the invention is therefore to select the light transmission level for a glazing provided with the thin-film systems described above without the above-mentioned drawback, namely without causing a significant optical change in the patterns in the event of heat treatment.

It is also an object of the invention to adjust the light transmission level and / or the glazing selectivity without correspondingly increasing the level of external light reflection too much, preferably by limiting this light reflection to less than 20%.

It is also an object of the invention to achieve this control of the level of light transmission in a relatively simple manner and sufficiently flexible for implementation on an industrial scale.

PL 200 037 B1

The subject of the invention is glazing for solar protection and / or thermal insulation, comprising at least one transparent substrate provided with a thin-layer system alternating with n functional layers with reflection properties in the range of infrared and / or solar radiation and n + 1 coatings composed of one or more layers made of dielectric so that each functional layer is sandwiched between two shells, and at least one coating comprises at least two layers made of dielectric, characterized in that at least one absorbent layer in the visible region is interposed between two dielectric layers of at least one of said coatings.

Preferably, the system comprises a single functional layer sandwiched between two coatings.

Preferably, the system comprises two functional layers alternating with three coatings.

Preferably, the functional layer (s) is / are made of silver or an alloy of metals containing silver.

Preferably, the absorbent layer (s) in the visible region is / are selected to be based on a metal or metal alloy such as Ti, Nb, Zr or NiCr, based on a metal oxide such as chromium oxide, iron oxide or substoichiometric titanium or zinc oxide, or based on a metal nitride such as titanium nitride, niobium nitride, zirconium nitride, chromium nitride or NiCr nitride.

Preferably, the thickness of the layer or each of the absorbent layers in the visible region is less than or equal to 7 nm, in particular less than or equal to 5 nm or 3 nm, preferably between 1 and 2 nm.

Preferably, at least one of the two layers between which the absorbent layer (s) is inserted in the visible region is made of an aluminum nitride and / or silicon nitride dielectric.

More preferably, the absorbent layer (s) in the visible region is / are interposed between two layers based on aluminum nitride and / or silicon nitride.

More preferably, the visible absorbent layer (s) is deposited between the metal oxide (s) layer and the silicon nitride and / or aluminum nitride layer.

Preferably, at least one of the coatings comprises an oxide layer selected from zinc oxide, tin oxide, titanium oxide, silicon oxide, tantalum oxide, niobium oxide, zirconium oxide, or a mixture of at least two of them.

Preferably, the or each functional layer is above the coating, the final layer of which is based on zinc oxide.

Preferably, the or each functional layer is under a coating, the first layer of which is based on zinc oxide.

Preferably, each of the coatings comprises at least one layer based on silicon nitride and / or aluminum nitride.

Preferably, a thin layer of metal or metal suboxide is interposed between each functional layer and at least one of the coatings that surround it, especially a sacrificial layer based on titanium, niobium or nickel-chromium, and preferably less than 2 nm thick.

Preferably, the system comprises two silver-based functional layers between the three coatings, with the absorbent layer (s) in the visible region inserted into an intermediate coating disposed between the two functional layers and / or within an upper coating placed above the second functional layer.

Preferably, the substrate-side layer arrangement comprises the following layers:

Si3N4 / ZnO / Ag / ZnO / Si3N4 / TiN / Si3N4 / ZnO / Ag / ZnO / Si3N4 or

Si3N4 / ZnO / Ag / ZnO / Si3N4 / NbN / Si3N4 / ZnO / Ag / ZnO / Si3N4 or

Si3N4 / ZnO / Ag / ZnO / Si3N4 / ZnO / Ag / ZnO / TiN / Si3N4 or

Si3N4 / ZnO / Ag / ZnO / Si3N4 / ZnO / Ag / ZnO / NbN / Si3N4 or

Si3N4 / ZnO / Ag / Ti / ZnO / TiN / Si3N4 / ZnO / Ag / Ti / ZnO / TiN / Si3N4 optionally with thin layers of partially or fully oxidized metal which are located on at least one of the faces of each of the silver layers.

Preferably the glazing is in the form of laminated glazing, asymmetric glazing or multiple glazing of the double glazing type.

Preferably, the absorbent layer (s) has / have an intrinsic light absorption of at least

3%, especially between 4 and 15% or between 6 and 12%.

PL 200 037 B1

Preferably, the system comprises two silver-based functional layers, with a light transmission TL of at most 65%, in particular between 40 and 65%, an external light reflection RL of less than or equal to 20%, in particular at most 17%, and values ​​of a 'and b' for external reflection. lights less than or equal to 1, preferably negative values.

Preferably, the absorbent layer (s) in the visible region and / or the multilayer system in its entirety do not change optically in the case of heat treatment such as annealing, bending or toughening.

It is also advantageously provided with at least one other coating of different functionality, in particular an anti-fouling coating, a hydrophobic coating, a hydrophilic coating or an anti-reflective coating.

The subject of the invention is, first of all, glazing comprising at least one transparent substrate provided with a thin-layer system consisting of alternately n functional layers with reflection properties in the range of infrared and / or solar radiation and n + 1 coatings composed of one or more layers made of dielectric so that each functional layer is sandwiched between two coatings. Moreover, at least one absorbent layer in the visible region is interposed between two dielectric layers of at least one of said coatings. In this configuration, the absorbent layer is neither in direct contact with the glass (which reduces the problems of diffusion of oxygen and alkali metal due to heat) nor in direct contact with silver (which reduces the problems with spoilage of the silver layer caused by oxidation of the absorbent layer when in contact with him, also under the influence of heat).

When n = 1, the system comprises a single functional layer sandwiched between two coatings.

When n = 2, the system includes two functional layers placed alternately with three coatings.

Preferably, the functional layer or layers are based on silver or a metal alloy containing silver.

The absorbent layer (or absorbent layers; the invention is not limited to the insertion of a single absorbent layer) may be selected to be made of various materials: it may be a metal or metal alloy of the type Ti, Nb, Zr or NiCr. It may also be a metal oxide such as chromium oxide, iron oxide, or substoichiometric zinc or titanium oxide. Finally, it may be a metal nitride such as titanium nitride, niobium nitride, zirconium nitride, chromium nitride or NiCr nitride.

Preferably, the thickness of the absorbent layer in the visible region according to the invention is limited to small values: its thickness is preferably less than or equal to 7 nm, or even less than 5 or 3 nm. Typically, a thickness between 1 and 3 nm is chosen: the first feature of the absorbent layer mentioned above is that it does not come into direct contact with the glass or the silver layer. The second feature is its thinness: it is very thin, which basically serves not to reduce the transition, but rather to adjust it to a few percent.

According to a preferred embodiment of the invention, the absorbent layer in the visible region lies between two dielectric layers, at least one of which is based on silicon nitride and / or aluminum nitride.

When n = 1, it lies between two layers of one of these nitrides. This is, in fact, the optimal configuration for the best envelope of the absorbent layer to isolate it from interactions with species that risk oxidizing it or degrading it (oxygen from the air or from glass or from an adjacent oxide layer, individuals diffusing from the silver layer by heat, etc. ). This is because silicon nitrides and / or aluminum nitrides are known to be highly chemically inactive, even at high temperatures. Not only do they fulfill their usual function of a dielectric with an optical function and a silver layer protection function (with a refractive index of about 2), but they also act as shield layers against the absorbent layer in the visible region.

In this configuration, an annealing, bending or quenching type heat treatment will have no (or very little) effect on the absorbent layer, with the nitride layers forming an oxygen barrier and preventing its oxidation. Consequently, the change in the light transmission in the overall system will not be more substantial than that observed in the absence of an absorbent layer (e.g. a change of at most 3%).

When n = 2, the visible absorbent layer is interposed in the coating between the one or more metal oxide (or silicon oxide) based layer and the aluminum nitride and / or silicon nitride layer. The preferred configuration consists of one in which the oxide layer lies beneath the absorbent layer and the nitride layer on top. According to this variation, there is direct contact

Between the absorbent layer and the oxide layer. Consequently, in the case of heat treatment, the absorbent layer may undergo oxidation but, on the one hand, it is limited (especially when there is a nitride above the layer isolating it from oxygen from the atmosphere) and, on the other hand, this oxidation may prove beneficial in in the sense that the absorbent layer traps oxygen and thus preserves other layers of the system from oxidation. In this case, the usually observed change in the transmission of the light of the system is slightly greater than that of the first variant, which may be as high as, for example, up to 4 or up to 5%.

At least one of the coatings of the system comprises at least one oxide layer selected from at least one of the following oxides: zinc oxide, tin oxide, titanium oxide, silicon oxide, tantalum oxide, niobium oxide and zirconium oxide. As explained in the above-mentioned EP-O 847 965, it is preferred that the coatings comprise both metal oxide layers and silicon nitride or aluminum nitride layers.

Thus, underneath at least one of the functional layers it is preferable to have a zinc oxide based layer which tends to facilitate the adhesion and crystallization of the silver based functional layer and increases its quality and high temperature durability.

It is also preferred that the functional layer or at least one of the functional layers is underneath the zinc oxide based layer to increase adhesion.

To ensure that the system can undergo heat treatment such as annealing, quenching or bending without undue optical alteration, it is preferred that each of the coatings comprises at least one layer made of silicon nitride and / or aluminum nitride.

Optionally, a thin layer of metal or sub-stoichiometric metal oxide (optionally nitrided) may be inserted between each functional layer and a coating placed above it and / or a coating placed beneath it. It may consist of layers of titanium, niobium or nickel-chromium alloy which are possibly partially oxidized during the deposition of the system (where the next layer is deposited by reactive sputtering in the presence of oxygen). They are usually referred to as tie layers (in the case of a layer below) or sacrificial or blocking layers (in the case of a layer on top).

The system also includes two silver-based functional layers with three coatings, and the visible-area absorbent layer is inserted into an intermediate coating, i.e. sandwiched between the two functional layers. It was found that in this configuration the absorbent layer appears to be the most stabilized / insulated and gives the best appearance in the external reflection of the glazing. An example of a system according to the invention is as follows:

- transparent substrate / Si3N4 / ZnO / Ag / ZnO / Si3N4 / TiN / NiN4 / ZnO / Ag / ZnO / Si3N4 or transparent substrate / Si3N4 / ZnO / Ag / ZnO / Si3N4 / NbN / NiN4 / ZnO / Ag / ZnO / Si3N4 optionally with thin metal layers (optionally partially oxidized) of the titanium type on at least one of the faces of the silver layers.

The invention relates to any glazing provided with the following systems: laminated glazing (wherein the system is deposited on one of a rigid substrate or a flexible polyethylene terephthalate (PET) substrate that is bonded to two rigid substrates by thermoplastic sheets); so-called asymmetric laminated glazing; and multiple-glazing of the double-glazed type, preferably with an arrangement on the 2 faces or on the 3 faces of the glazing (typically the faces of the substrates are numbered from the outermost face to the innermost face of the glazing when installed in the room). The invention relates in particular to double glazing which exhibits the following properties:

* Light transmission TL of at most 75%, in particular at most 70% or 65%, in particular at least 40%, or between 55 and 65% or between 45 and 55%, especially in the area of ​​50% and 60%, and / or * external Light reflectance RL less than or equal to 20%, in particular not more than 17%, and / or * values ​​of a 'and b' in external light reflection a less than or equal to 1, preferably negative values, even after treatment hardening type), especially in the case of systems consisting of two silver layers.

It is therefore essential that the absorbent layer in the visible region, inserted in particular in conventional systems, makes it possible to adjust the light transmission through them without any optical change in the event of heat treatment and / or without disturbing the appearance of the substrate upon reflection.

PL 200 037 B1

Preferably, the absorbent layer (s) according to the invention has an intrinsic light absorption of at least 3%, in particular between 4 and 15% or between 6 and 12% (each or all of said absorbent layers, if several of them are used in the invention). .

The invention will be described in more detail with the aid of the following examples.

In all of the examples, the arrays are deposited on a 6 mm thick substrate made of transparent soda-lime-quartz glass. The substrate is then deposited as double glazing with a second substrate of identical glass such that the array is on the 2 faces, the cavity between the 2 glass panes is filled with argon and is 12 mm thick. Such glazing is generally intended for buildings as thermal insulation and / or solar control glazing.

In all the examples, a first arrangement (arrangement) is made of double glazing with glass provided with un-toughened layers, and then a second arrangement (arrangement) is made in which the glass, after being provided with a multi-layer arrangement, is subjected to a toughening operation under standard conditions including range (including heating the glass to 640 ° C for several minutes).

All layers of the systems are deposited by magnetic field assisted sputtering: (oxide layers by reactive sputtering in the presence of oxygen using metal targets or possibly sub-stoichiometric ceramic targets, nitride layers by reactive sputtering in the presence of nitrogen).

Comparative example 1

The multilayer system was as follows (the table below gives the layer thicknesses in nanometers):

<td></td><td>Comparative Example 1</td>

<td>Glass</td><td>nm</td>

<td>Si3N4</td><td> 31,0</td>

<td>ZnO</td><td> 10,0</td>

<td>Ag</td><td> 9,5</td>

<td>Ti</td><td> 0,8</td>

<td>ZnO</td><td> 10,0</td>

<td>Si3N4</td><td> 64,0</td>

<td>ZnO</td><td> 10,0</td>

<td>Ag</td><td> 17,5</td>

<td>Ti</td><td> 0,8</td>

<td>ZnO</td><td> 10,0</td>

<td>Si3N4</td><td> 21,5</td>

This example is comparative as it lacks an absorbent layer in the visible region between the two dielectric layers. The two titanium layers above the silver layer are very thin and will oxidize (at least partially) when depositing the next layer made of ZnO (as in the following examples).

Examples 2 and 3 according to the invention

These examples repeat the setup of Example 1, with the addition of a titanium nitride layer in the center of the Si3N4 layer of the dielectric coating lying between the two silver layers. This is the first embodiment of the invention in which the absorbent layer is protected against oxidation by two layers surrounding it.

The table below gives the thicknesses in nm of each layer.

<td></td><td>Example 2</td><td>Example 3</td>

<td> 1</td><td> 2</td><td> 3</td>

<td>Glass</td><td> -</td><td> -</td>

<td>Si3N4</td><td> 31,0</td><td> 31,0</td>

<td>ZnO</td><td> 10,0</td><td> 10,0</td>

PL 200 037 B1 cont. table

<td> 1</td><td> 2</td><td> 3</td>

<td>Ag</td><td> 9,5</td><td> 9,5</td>

<td>Ti</td><td> 0,8</td><td> 0,8</td>

<td>ZnO</td><td> 10,0</td><td> 10,0</td>

<td>Si3N4</td><td> 32,0</td><td> 32,0</td>

<td>TiN</td><td> 0,7</td><td> 1,4</td>

<td>Si3N4</td><td> 32,0</td><td> 32,0</td>

<td>ZnO</td><td> 10</td><td> 10,0</td>

<td>Ag</td><td> 17,5</td><td> 17,5</td>

<td>Ti</td><td> 0,8</td><td> 0,8</td>

<td>ZnO</td><td> 10,0</td><td> 10,0</td>

<td>Si3N4</td><td> 21,5</td><td> 21,5</td>

The table below gives, for each of Examples 1 to 3, the following data:

- light transmission TL in% with D65 illuminator;

- AD dominant wavelength in transmission, in nm;

- value of the external light reflection RL, ext in%;

- values ​​of a * and b * for light reflection according to the colorimetric system (L *, a *, b *); and

- solar factor SF in accordance with DIN.

The values ​​are given for double glazing without toughening multi-layered glass ("no toughening) and for double glazing with multi-layered toughened glass (" toughened) ".

<td>Examples</td><td>Tl</td><td>AD</td><td>RL, ext</td><td>and*</td><td>b *</td><td>SF</td>

<td>Comparative example 1</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td rowspan="2">Without hardening With hardening</td><td> 63,4</td><td> 516</td><td> 17,1</td><td> -4,4</td><td> -3,5</td><td> 34</td>

<td> 65,3</td><td> 508</td><td> 21,1</td><td> -3,8</td><td> -4,7</td><td> 34</td>

<td>Example 2</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td rowspan="2">Without hardening With hardening</td><td> 60,2</td><td> 496</td><td> 16,4</td><td> -3,9</td><td> 0,7</td><td> 33</td>

<td> 62,3</td><td> 493</td><td> 17,4</td><td> -0,6</td><td> -2,5</td><td> 33</td>

<td>Example 3</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td rowspan="2">Without hardening With hardening</td><td> 57,6</td><td> 501</td><td> 13,4</td><td> -4,6</td><td> -5,0</td><td> 31</td>

<td> 59,5</td><td> 497</td><td> 14,5</td><td> -2,7</td><td> -7,8</td><td> 31</td>

The following conclusions can be drawn from the above data:

- with an additional layer of TiN according to the invention, it is possible for the TL to be lowered in a controlled manner from 2 to 7 or 8% in order to consequently adjust its thickness, keeping a moderate level of external reflection, clearly less than 20% (same reduction TL could be obtained by thickening the silver layer, but to the detriment of external light reflection which then increases significantly);

- such matching can be made using a very thin layer: less than 2 nm of TiN, thus without significantly increasing the unit time to fabricate the system and without significantly increasing neither cost nor complexity;

the addition of this absorbent layer also has, as a direct consequence, a reduction of SF of at least 1 to 3 points;

- even without quenching, the absorbent layer according to the invention has a favorable effect on external reflection by reducing it by at least 1 to 4% (for comparable TL levels) and this

The PL 200 037 B1 allows the preservation of negative a * and b * values ​​(i.e. the residual color in the reflection in a cyan color, which is currently the most desirable shade); and

- all these benefits are retained even when the system is quenched: of course there are slight variations in TL or RL but the light reflection remains well below 20% (unlike the comparative example where there is an increase of almost 4% and the 20% threshold is exceeded). This is evidence that the TiN layer is stable and has not changed optically (or only slightly) because it is encapsulated between two nitrides.

It should also be noted that it may be advantageous for the two nitride layers surrounding the TiN layer not to be of the same thickness, and the layer furthest from the substrate may be thicker, e.g. by one third (about 20, 30 or 40%) than the other layer. (or vice versa).

Moreover, it should be noted that the TiN layer may be replaced with an NbN layer or a metal layer of the Ti, Nb or Zr type.

Finally, a large asymmetry in the thickness of the two silver layers must be noted, which is especially the case when following the description of the aforementioned EP-O 844 219.

Examples 4, 5 and 5a

These examples are similar to Example 3, with an NbN layer (Example 4) and a TiN layer (Example 5) as absorbent layers. They are again in accordance with the first variant of the invention.

The table below gives the thicknesses in nm of each layer of the system:

<td></td><td>Example 4</td><td>Example 5</td><td>Example 5a</td>

<td>Glass</td><td> -</td><td> -</td><td> -</td>

<td>Si3N4</td><td> 31,0</td><td> 31,0</td><td> 29,0</td>

<td>ZnO</td><td> 10,0</td><td> 10,0</td><td> 10,0</td>

<td>Ag</td><td> 8,5</td><td> 8,5</td><td> 8,5</td>

<td>Ti</td><td> 0,8</td><td> 0,8</td><td> 0,8</td>

<td>ZnO</td><td> 10,0</td><td> 10,0</td><td> 10,0</td>

<td>Si3N4</td><td> 31,0</td><td> 31,0</td><td> 30,0</td>

<td>Absorbent layer</td><td>NbN: 1.4</td><td>TiN: 1.4</td><td>TiN: 2</td>

<td>Si3N4</td><td> 31,0</td><td> 31,0</td><td> 30,0</td>

<td>ZnO</td><td> 10,0</td><td> 10,0</td><td> 10,0</td>

<td>Ag</td><td> 17,0</td><td> 17,0</td><td> 20,2</td>

<td>Ti</td><td> 0,8</td><td> 0,8</td><td> 0,8</td>

<td>ZnO</td><td> 10,0</td><td> 10,0</td><td> 10,0</td>

<td>Si3N4</td><td> 23,0</td><td> 23,0</td><td> 20,0</td>

It should be noted that Examples 2 to 5a according to the invention have, after quenching, a good optical quality, in particular without the presence of corrosion pits or small wetting defects.

The table below gives the same photometric data for these three examples as for the previous Examples 1 to 3 under the same conventions, and in addition:

- PT transition purity as a percentage; and

- the value of Δ E in reflection (without titer), which in the colorimetric system (L *, a *, b *) is calculated according to the formula [(a * f -a * i)² + (b * f-bi)² + (L * fL * i)²]^1/2, where a^*i, b * i and L * j are the values ​​before quenching, aa * f, b * f and L * f - after quenching.

PL 200 037 B1

<td>Examples</td><td>Tl</td><td>AD</td><td>PT</td><td>^R L, ext</td><td>and*</td><td>b *</td><td>AE</td><td>SF</td>

<td>Example 4</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td rowspan="2">Before hardening After hardening</td><td> 58,5</td><td> 537</td><td> 3,4</td><td> 14,2</td><td> -1,0</td><td> -7,8 -</td><td></td><td> 32</td>

<td> 59,6</td><td> 521</td><td> 2,2</td><td> 15,7</td><td> -2,7</td><td> -9,0</td><td> 2,9</td><td> 33</td>

<td>Example 5</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td rowspan="2">Before hardening After hardening</td><td> 58,6</td><td> 542</td><td> 4,6</td><td> 14,4</td><td> -0,7</td><td> -9,0 -</td><td></td><td> 32</td>

<td> 60,4</td><td> 531</td><td> 2,8</td><td> 16,0</td><td> -2,1</td><td> -10,1</td><td> 2,7</td><td> 33</td>

<td>Example 5a</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td rowspan="2">Before hardening After hardening</td><td> 49,4</td><td> 500</td><td> 6,4</td><td> 16,2</td><td> -1,9</td><td> -5,3 -</td><td></td><td> 26</td>

<td> 50,6</td><td> 494</td><td> 2,8</td><td> 17,9</td><td> -1,6</td><td> -6,2 -</td><td></td><td> 26</td>

It should be noted that the increase in light transmission after quenching is very limited: about 1.5% for the NbN layer, about 2 or 1.2% for the TiN layer, depending on its thickness. In this case, too, the color in the external reflection changes little after quenching: the values ​​of a * and b * remain negative, with a decrease of a * around -2 and a change of b * ± 1. Example 5a is especially good in this regard with a * value that only changes by +0.3 and a b * value that only changes by 0.9.

Example 6

This example is in accordance with the second embodiment of the invention: the absorbent layer lies in the upper dielectric layer (above the second silver layer), between the oxide layer and the nitride layer.

The table below gives the thicknesses in nm of each layer of the system:

<td></td><td>Example 6</td>

<td>Glass</td><td>nm</td>

<td>Si3N4</td><td> 31,0</td>

<td>ZnO</td><td> 10,0</td>

<td>Ag</td><td> 8,5</td>

<td>Ti</td><td> 0,8</td>

<td>ZnO</td><td> 10,0</td>

<td>Si3N4</td><td> 62,0</td>

<td>ZnO</td><td> 10,0</td>

<td>Ag</td><td> 17,0</td>

<td>Ti</td><td> 0,8</td>

<td>ZnO</td><td> 10,0</td>

<td>TiN</td><td> 1,4</td>

<td>Si3N4</td><td> 23,0</td>

The glass was deposited as before as double glazing, without toughening and then after toughening. The optical change after quenching is as follows:

- aT_l = T._L.(after quenching) - T._L. (before quenching) = + 2.4%;

- Ab * in external reflection = b * (after quenching) - b * (before quenching) = 2

- RL, ext (after quenching) = 16.5%; and

- TL / SF ratio = approximately 62-63 / 33.

There are no corrosion pits, even if the deposition parameters are not very well chosen, and the dehumidification defects are very small and not numerous.

PL 200 037 B1

A number of configurations in which the absorbent layer lies between the oxide layer and the nitride layer were examined by assessing the optical quality of the systems after quenching. These are the variations corresponding to Example 6 listed below (the thicknesses of all layers, except the absorbent layer, are the same as those according to Example 6):

Example 6.1

Substrate / Si3N4 / ZnO / Ag / Ti / ZnO / TiN (1 to 3 nm) / Si3N4 / ZnO / Ag / Ti / ZnO / Si3N4;

Example 6.2

Substrate / Si3N4 / ZnO / Ag / Ti / ZnO / Si3N4 / TiN (1 to 3 nm) / ZnO / Ag / Ti / ZnO / Si3N4;

Example 6.3

Substrate / Si3N4 / ZnO / Ag / Ti / ZnO / Si3N4 / ZnO / Ag / Ti / ZnO / TiN (1 to 3 nm) / Si3N4;

Example 6.4

Substrate / Si3N4 / ZnO / Ag / Ti / ZnO / TiN (1 to 2 nm) / Si3N4 / ZnO / Ag / Ti / ZnO / TiN (1 to 2 nm) / Si3N4.

This example therefore uses two absorbent layers.

The optical quality of these glasses after toughening was assessed by a defect density of less than 2 micrometers in size and by a defect density of at least 2 micrometers in size. The most preferred configurations are those of Example 6.3 and those of Example 6.4:

- in the case of Example 6.3, with a 2 nm and 3 nm absorbent layer, no defects greater than 2 micrometers or less than 2 micrometers;

- in the case of Example 6.4, there are few defects when the two absorbent layers are each 1 nm thick, and no defects if the first layer starting from the substrate is 1 nm thick and the second layer is 2 nm thick (configuration according to Example 6.3 can be considered better than that of Example 6.4 as any defects at 2 nm in one case and 2 + 1 nm at least in the other case are avoided);

- in the case of Example 6.2, the optimal configuration is observed with an absorbent layer of 3 nm (few defects); for Example 6.1, the optimal configuration is also observed with the 3 nm absorbent layer (no defects less than 2 microns, few defects of at least 2 microns); and

- for comparison, if Example 6.1 is repeated but omitting this absorbent layer, after quenching there is a high density of both defects less than 2 microns and defects of at least 2 microns - unacceptable density for a commercial product.

It can therefore be concluded that two parameters are taken into account to ensure a good optical quality of the systems according to the invention after quenching: the position of the absorbent layer or layers in the array (preferably within the outermost dielectric or within the intermediate dielectric of systems comprising two silver layers) and its thickness or thicknesses (which may vary according to the configurations, but which are preferably at least 1.5 or 2 nm, and even more in the 3 nm region when the absorbent layer is within the intermediate dielectric).

It can also be found that the presence of the absorbent layer improves overall the heat treatment behavior of the system.

Comparative example 7

This example is given for comparison to the extent that in this case the absorbent layer is in direct contact with the glass:

<td></td><td>Comparative example 7</td>

<td> 1</td><td> 2</td>

<td>Glass</td><td>nm</td>

<td>TiN</td><td> 1,4</td>

<td>Si3N4</td><td> 31,0</td>

<td>ZnO</td><td> 10,0</td>

<td>Ag</td><td> 8,5</td>

<td>Ti</td><td> 0,8</td>

<td>ZnO</td><td> 10,0</td>

<td>Si3N4</td><td> 62,0</td>

<td>ZnO</td><td> 10,0</td>

PL 200 037 B1 cont. table

<td> 1</td><td> 2</td>

<td>Ag</td><td> 17,8</td>

<td>Ti</td><td> 0,8</td>

<td>ZnO</td><td> 10,0</td>

<td>Si3N4</td><td> 23,0</td>

Again, the glass is deposited as double glazing, without toughening and then after toughening: AT_L. = + 4%, Ab * in external reflection = -2 to -3; very poor optical quality - extensive corrosion pitting.

This example shows that placing the layer in direct contact with the glass has a detrimental effect on the optical quality of the glass after toughening, with a significant increase in TL.

In summary, the insertion of an absorbent layer in the visible region (and beyond) between nitride-type and / or oxide-type dielectrics allows good light transmission control and SF reduction, without optical disturbance to be feared, most especially in external reflection, and especially when the layers subject to heat treatment: limited overall optical change in the system in case of toughening (less than +/- 3% or even +/- 2% of TL); maintain a moderate level of external reflection and a satisfactory external reflection colorimetric response; and a satisfactory optical quality after toughening.

Glazing consisting of a substrate provided with the system according to the invention may also include one or more other functionalities: it may include, e.g. more anti-reflective coatings. These coatings are preferably disposed on at least one outer face of the glazing (on the outward facing faces, as opposed to the inward facing faces of a thermoplastic sheet in the case of laminated glass or the faces facing an air cavity or gas cavity) or a vacuum cavity in the case of insulating glazing).

The system may also be a heating system, with appropriate electrical supply and connections.