Material and glazing comprising said material

MATERIAL AND GLAZING COMPRISING SUCH MATERIAL

The invention relates to the field of materials comprising a glass substrate coated with a photocatalytic layer.

Photocatalytic layers, in particular those based on titanium oxide, are known to confer self-cleaning and anti-fouling properties on the substrates which they coat. Two properties are at the origin of these advantageous characteristics. Titanium oxide is first of all photocatalytic, that is to say that it is capable, under adequate radiation, generally ultraviolet radiation, of catalyzing the degradation reactions of organic compounds. This photocatalytic activity is initiated within the layer by the creation of an electron-hole pair. In addition, titanium oxide exhibits an extremely pronounced hydrophilicity when it is irradiated with this same type of radiation. This strong hydrophilicity allows the evacuation of mineral soiling under water runoff, for example rainwater. Such materials, in particular glazing, are described for example in application EP-A-0 850 204.

There are glazings combining such self-cleaning and anti-fouling properties with solar control properties. By solar control is meant the ability to reduce the amount of solar energy likely to pass through the glazing and to heat the rooms of dwellings and the passenger compartments of vehicles. Glazing with such properties makes it possible to avoid excessive heating of the aforementioned rooms or compartments and, if necessary, to limit the energy consumption linked to their air conditioning. It is thus known from the application WO 03/050056 to deposit photocatalytic layers on tinted glasses. Tinted glasses, however, have a low selectivity, which corresponds to the ratio between light transmission and energy transmission. There are also glazings commonly called “dual coatings”, which include a photocatalytic layer on one side and a solar control coating on the other side. The advantage of such an arrangement is that the solar control coating, which often has poor climatic durability, is protected by being located opposite 2 of the glazing, therefore inside the building, while the photocatalytic coating is in side 1, outside the building, where it is most useful. However, such glazing poses processing difficulties because the layer or stack deposited on the underside risks being damaged during the conveying steps, in particular due to contact with the conveying rollers. It would therefore be useful to be able to offer glazings having on the same face, therefore on face 1, the solar control and self-cleaning functionalities. However, attempts to solve this problem have so far proved unsuccessful due to the poor climatic sustainability of the stacks obtained.

A first object of the invention is to propose photocatalytic materials which can be incorporated in solar control glazing, which do not have the abovementioned drawbacks. A second object of the invention is to provide solar control glazing having excellent climatic durability within the meaning of standard EN 1096-2: 2001. A third object of the invention is to propose materials having a neutral tint in transmission and / or in reflection.

These objects are achieved by a material comprising a glass substrate coated on at least one of its faces with a stack of thin layers comprising from said substrate at least one lower dielectric layer, at least one functional layer of metal or metallic nitride, at at least one upper dielectric layer, at least one layer of titanium oxide at least partially crystallized in anatase form, said metal or metal nitride being based on Nb, NbN, W, WN, Ta, TaN or any of their alloys or solid solutions.

The metals or nitrides chosen, in combination with the dielectric layers and the titanium oxide layer, surprisingly make it possible to obtain excellent climatic durability and to meet the requirements of standard EN 1096-2: 2001, even after 56 test days. Consequently, such glazing can be arranged so that the stack is located opposite 1, that is to say outside the building, where the photocatalytic layer can fully play its role vis-à-vis the dirt and air pollution. This combination therefore makes it possible to propose glazings having both self-cleaning and anti-fouling properties and solar control properties but which do not have the drawbacks of “dual coatings” known from the prior art.

Preferably, the substrate is a glass sheet. The sheet can be flat or curved, and have any type of dimension, in particular greater than 1 meter. The glass is preferably of the soda-lime-silica type, but other types of glass, such as borosilicate glasses or aluminosilicates can also be used. The glass can be clear or extra-clear, or even tinted, for example in blue, green, amber, bronze or gray. The thickness of the glass sheet is typically between 0.5 and 19 mm, in particular between 2 and 12 mm, or even between 4 and 8 mm.

The stack of thin layers preferably does not comprise silver or copper layers because these layers risk imparting poor climatic resistance to the glazing, which is in particular detrimental when the stack must be placed opposite 1 of the glazing.

The best results, in particular in terms of climatic durability, are obtained when the metal or the metal nitride is chosen from NbN, Nb, WN, W. These metals or nitrides also have good absorption properties in the visible range and infrared. The thickness of the metal or metallic nitride layer must be adapted according to the light transmission targeted. It typically varies between 3 and 50 nm, in particular between 5 and 30 nm, or even between 5 and 20 nm. The light transmission of the material is preferably between 5 and 70%, especially between 10 and 60%.

The or each lower dielectric layer is intended to protect the metal or nitride layer against the diffusion of alkaline ions from the substrate, against oxidation and delamination. Preferably, one or two upper dielectric layers are used. The or each upper dielectric layer is intended to reduce the intrinsic reflection of the metal or nitride layer and to protect the latter against corrosion and mechanical attack (scratches, abrasion, etc.). The at least one lower dielectric layer and / or the at least one upper dielectric layer is preferably chosen from silicon or aluminum oxide, nitride or oxynitride, tin oxide or mixed oxide of tin and zinc. Silicon nitride is preferred because it provides excellent mechanical and quench resistance, and can be easily deposited by magnetron sputtering. Each of these layers can be pure or doped. It is thus frequent to dop the layers of silica or silicon nitride with an atom such as aluminum in order to facilitate their deposition by sputtering. The thickness of the or each lower dielectric layer and / or the or each upper dielectric layer is preferably between 5 and 100 nm, in particular between 10 and 50 nm.

When the functional layer is metallic, in particular made of niobium or based on niobium, it is preferable to interpose a blocker layer between the functional layer and the upper dielectric layer closest to the functional layer, or even also between the functional layer and the lower dielectric layer closest to the functional layer. This blocker layer is intended to prevent oxidation or nitriding of the functional metal layer during possible heat treatments, for example quenching. This blocker layer is very thin, preferably between 1 and 5 nm thick. It is preferably made of a metal chosen from titanium or chromium or an alloy of nickel and chromium. The presence of blocker layer (s) makes the stack quenchable when the functional layer is made of metal, in the sense that the stack has similar optical properties before and after quenching.

The functional layer, in particular when it is made of nitride, can itself be surmounted by an additional layer of nitride, for example of niobium, titanium, zirconium or chromium nitride. This additional layer optionally makes it possible to more easily adjust the reflection properties, in particular the chromatic values.

Preferably, at least one layer of silica is interposed between the at least one upper dielectric layer and the at least one layer of titanium oxide at least partially crystallized in anatase form and / or between the substrate and the lower most dielectric layer. close to the substrate. This additional layer improves the photocatalytic activity of the coating. In the second alternative, the variations in color in reflection of the stack linked to possible variations in thickness of the silica layer are minimized. In the first alternative, however, the thickness and uniformity of the silica layer must be perfectly controlled for good control of the color in reflection of the stack. The or each layer of silica preferably has a thickness of between 5 and 100 nm, in particular between 10 and 40 nm. The silica layer can be pure or doped, for example with aluminum atoms.

The preferred stacks are:

- Glass / Si₃NOT₄ / NbN / Si₃NOT₄ / Ti0₂

- Glass / Si₃NOT₄ / NbN / Si₃NOT₄ / Si0₂ / Ti0₂

- Glass / Si0₂ / Yes₃NOT₄ / NbN / Si₃NOT₄ / Ti0₂

- Glass / Si0₂ / Yes₃NOT₄ / NbN / Si₃NOT₄ / Si0₂ / Ti0₂

- Glass / Si₃NOT₄ / WN / Si₃NOT₄ / Ti0₂

- Glass / Si₃NOT₄ / WN / Si₃NOT₄ / Si0₂ / Ti0₂

- Glass / Si0₂ / Yes₃NOT₄ / WN / Si₃NOT₄ / Ti0₂

- Glass / Si0₂ / Yes₃NOT₄ / WN / Si₃NOT₄ / Si0₂ / Ti0₂

- Glass / Si₃NOT₄ / Ti / Nb / Ti / Si₃NOT₄ / Ti0₂ - Glass / Si₃NOT₄ / Ti / Nb / Ti / Si₃NOT₄ / Si0₂ / Ti0₂

- Glass / Si0₂ / Yes₃NOT₄ / Ti / Nb / Ti / Si₃NOT₄ / Ti0₂

- Glass / Si0₂ / Yes₃NOT₄ / Ti / Nb / Ti / Si₃NOT₄ / Si0₂ / Ti0₂

In these nonlimiting examples of stacks according to the invention, the titanium blocker layer can be replaced by a chromium layer. The ranges of thicknesses for the different layers of the stack are those described above and are not repeated here so as not to make the text cumbersome.

Titanium oxide can be pure or doped, for example with transition metals (for example W, Mo, V, Nb), lanthanide ions or noble metals (such as for example platinum, palladium), or also by nitrogen or carbon atoms. These different forms of doping make it possible either to increase the photocatalytic activity of the material, or to shift the gap of the titanium oxide towards wavelengths close to the visible range or included in this range.

The titanium oxide layer is normally the last layer of the stack deposited on the substrate, in other words the layer of the stack furthest from the substrate. It is indeed important that the photocatalytic layer is in contact with the atmosphere and its pollutants. It is however possible to deposit on the photocatalytic layer a very thin layer, generally discontinuous or porous. It may for example be a layer based on noble metals intended to increase the photocatalytic activity of the material. It may also be thin hydrophilic layers, for example made of silica, as taught in applications WO2005 / 040058 or 2007/045805. The thickness of the titanium oxide layer is preferably between 5 and 50 nm, in particular between 5 and 20 nm.

The use of a stack on one side of the substrate makes it possible to considerably simplify the deposition process, to reduce the cost thereof, and to avoid the risks of damaging the layers during conveying or handling.

The material according to the invention preferably has an energy transmission (within the meaning of standard NF EN 410: 1998) of between 2 and 70%, in particular between 5 and 65%.

The invention also relates to a process for obtaining a material, in which the layers of the stack are deposited by magnetron sputtering or chemical vapor deposition (CVD).

In the sputtering process, in particular assisted by a magnetic field (magnetron process), excited species of a plasma tear off the atoms of a target located opposite the substrate to be coated. For the deposition of the titanium oxide layer, the target can in particular be made of metallic titanium or of TiO_x, the plasma must contain oxygen (we speak of reactive sputtering). It is also possible to deposit layers of S1₃NOT₄ or S1O₂ using a silicon target, doped with aluminum, in a plasma containing argon and nitrogen or oxygen respectively. The functional layer of metal or nitride can be deposited using a metal target, respectively in an inert atmosphere (for example argon) or in a reactive atmosphere containing nitrogen.

Chemical vapor deposition, generally designated by its English acronym CVD, is a pyrolysis process based on gaseous precursors which decompose under the effect of the heat of the substrate. In the case of titanium oxide, the precursors can be, for example, titanium tetrachloride, titanium tetraisopropoxide or titanium tetraorthobutoxide.

The deposition step is preferably followed by a heat treatment, in particular of the quenching, bending, annealing type, or of a rapid treatment using laser radiation or a flame, in particular when the layer d titanium oxide was deposited by sputtering. This heat treatment is intended to crystallize the titanium oxide in the anatase form. The rapid treatment is preferably a treatment as described in application WO2008 / 096089.

The invention also relates to a glazing unit comprising at least one material according to the invention. The glazing can be single or multiple (in particular double or triple), in the sense that it can comprise several sheets of glass providing a space filled with gas. The glazing can also be laminated and / or toughened and / or hardened and / or curved. In the case of single or multiple glazing, the solar control coating is preferably deposited on face 1.

The solar control glazing thus obtained also has self-cleaning, anti-fouling, anti-fogging and vision-improving properties in rainy weather. When the functional layer is a metal, for example Nb, the emissivity of the stack is reduced, typically to values ​​of 0.5 or less, or even 0.3. The stack therefore has both solar control and low emissivity properties. When the stack is placed on face 1, this latter property is particularly advantageous for limiting condensation (fogging and / or frost) on the surface of double glazing, in particular when they are inclined (for example when they are integrated into roofs or verandas). The presence of a low-emissive layer on face 1 makes it possible to limit heat exchanges with the outside during the night, and therefore to maintain a surface temperature of the glass above the dew point. The appearance of mist or frost is therefore greatly reduced or even completely eliminated.

In the case of simple glazing, the stack can also be deposited on face 2, providing properties of ease of cleaning and anti-fogging.

The other side of the coated substrate according to the invention, or if necessary one side of another substrate of the multiple glazing, can be coated with another functional layer or with a stack of functional layers. It may especially be another photocatalytic layer, for example another stack according to the invention. They can also be layers or stacks with a thermal function, in particular sunscreen or low-emissivity layers, for example stacks comprising a silver layer protected by dielectric layers. It may also be a mirror layer, in particular based on silver. Finally, it may be a lacquer or an enamel intended to opacify the glazing to make it a facade cladding panel called lighter. The sill is placed on the facade alongside the non-opaque glazing and allows to obtain fully glazed facades that are homogeneous from an aesthetic point of view.

The invention finally relates to the use of glazing according to the invention as solar control glazing for the building or vehicles (land, air, rail). The glazing according to the invention is preferably used on face 1, in the sense that the stack is placed outside the building or the vehicle. In the context of applications in the building sector, the glazing is preferably used in verandas, on the facade or on the roof. For automotive applications, the glazing may advantageously form roofs.

The invention will be better understood in the light of the following nonlimiting examples.

All the examples, comparative or according to the invention, are produced using a magnetron sputtering deposition on clear glass substrates sold under the trademark Planilux by the applicant.

The layers of silicon nitride are obtained from a target of silicon doped with 8% by weight of aluminum, under an atmosphere composed of 45% of argon and 55% of nitrogen. The niobium layers are obtained from a niobium target under an argon atmosphere. The niobium nitride layers use the same type of target, but under an atmosphere composed of 45% argon and 55% nitrogen. The titanium layers are obtained using a titanium target under an argon atmosphere. The titanium oxide layers are obtained either from a titanium target under an atmosphere composed of argon and oxygen, or from a sub-stoichiometric titanium oxide target under an atmosphere d argon enriched with 1% oxygen. The silica layers are obtained using a silicon target doped with 8% by mass of aluminum, under an atmosphere composed of 75 of argon and 25% of oxygen. l^time series of examples

Table 1 shows the composition and thickness of comparative example C1 and examples according to the invention 1 to 5. The stacking is carried out in the order of the table, the first line corresponding to the layer furthest from the substrate and the last line to that in contact with the substrate. As in the rest of the description, the thicknesses are physical thicknesses expressed in nm.

Table 1

<img file="WO2011030049A2_D0001.tif" />

Table 2 below indicates the optical properties of comparative example C1 and examples according to the invention 1 to 5. The following are reproduced:

light transmission (TL) and light reflections on the glass side (RL_V) and layer side (RL_VS), as well as energy transmission (TE) within the meaning of standard NF EN 410: 1998,

the corresponding chromatic values ​​L * a * b * (in transmission and in reflection on the glass side and on the layer side), calculated by taking into account the illuminant D65 and the reference observer CIE-1931. Table 2

<img file="WO2011030049A2_D0002.tif" />

The samples of Examples C1 and 1 to 5 are then subjected to an annealing treatment, at a temperature of 620 ° C. for 10 minutes.

Table 3 below indicates the optical properties of the comparative example C1 and of the examples according to the invention 1 to 5 after this annealing treatment. It also indicates the color variations in transmission and reflection induced by annealing. These variations are expressed by the quantity ΔΕ * (which corresponds to the square root of the sum of the squares of the differences in chromatic values ​​before and after annealing). The index t, v, or c corresponds respectively to the transmission, the reflection on the glass side and the reflection on the layer side.

Table 3

<img file="WO2011030049A2_D0003.tif" />

The low values ​​of ΔΕ * show that the stacks do not see their colorimetric properties evolve significantly due to the annealing treatment. The photocatalytic activity of the comparative samples C1 and according to the invention 1 to 5 was measured according to the following test.

An aqueous solution of methylene blue is placed in contact in a sealed cell with the coated substrate (the latter forming the bottom of the cell). After exposure to ultraviolet radiation for 30 minutes, the concentration of methylene blue is evaluated by a measurement of light transmission. The photocatalytic activity value, expressed in gl^_1.min^_1, corresponds to the decrease in the concentration of methylene blue per unit of exposure time.

Table 4 below reproduces the results obtained.

Table 4

<img file="WO2011030049A2_D0004.tif" />

The presence of a silica layer between the second dielectric layer and the photocatalytic layer therefore makes it possible to significantly increase the photocatalytic activity of the coating. Analysis by secondary ionization mass spectroscopy (SIMS) confirms that the amount of sodium within the photocatalytic layer is much lower when the silica layer is present.

2^eme series of examples

Table 5 shows the composition and thickness of comparative example C2 and examples according to the invention 6 and 7. The stacking is carried out in the order of the table, the first line corresponding to the layer furthest from the substrate and the last line to that in contact with the substrate. As in the rest of the description, the thicknesses are physical thicknesses expressed in nm.

Table 5

<img file="WO2011030049A2_D0005.tif" />

Samples C2 and 6 and 7 underwent a quenching treatment. The optical properties of the samples after quenching are summarized in Table 6. Table 6

<img file="WO2011030049A2_D0006.tif" />

The hardened C2, 6 and 7 samples have undergone the various climatic durability tests described in standard EN 1096-2: 2001. These are the tests:

resistance to condensation, according to annex B of standard EN 1096-2: 2001, noted "HH"

resistance to acid attack, according to appendix C of the above-mentioned standard, noted “SO₂ »,

- resistance to neutral salt spray, according to annex D of the above-mentioned standard, noted “BSN”.

Table 7 shows the results in terms of visual control and colorimetric variations and light reflection and transmission after 56 days of testing. In the lines "visual inspection", "OK" indicates success - no fault, "NOK" indicates failure. Table 7

<img file="WO2011030049A2_D0007.tif" />

The soaked samples C2, 6 and 7 also underwent an accelerated aging test consisting of immersing them in boiling demineralized water for 2 hours. The colorimetric variations due to such a treatment are presented in table 8.

Table 8

<img file="WO2011030049A2_D0008.tif" />

The stacks according to the invention generally have better climatic resistance than the comparative stack, in particular to the accelerated boiling water test as well as to the tests for resistance to condensation and to neutral salt spray. The titanium oxide layer, in addition to imparting photocatalytic properties, therefore considerably improves the climatic durability of the glazings according to the invention, which makes it possible to position the stack in front 1.

In comparison, solar control layers comprising a layer of silver between several layers of silicon nitride and covered with a layer of titanium oxide do not pass the BSN, HH and SO tests.₂even after 21 days of testing.

3^eme series of examples

Table 9 presents the composition and the thickness of comparative example C3 and of the example according to the invention 8. The stacking is carried out in the order of the table, the first line corresponding to the layer furthest from the substrate and the last line to that in contact with the substrate, As in the rest of the description, the thicknesses are physical thicknesses expressed in nm.

Table 9

<img file="WO2011030049A2_D0009.tif" />

Table 10 summarizes the colorimetric and energy properties of Examples C3 and 8 after quenching. The term "TE" corresponds to energy transmission within the meaning of standard NF EN 410: 1998.

Table 10

<img file="WO2011030049A2_D0010.tif" />

The samples, as they were and soaked, underwent an accelerated aging test which consisted in immersing them in boiling demineralized water for 2 hours. The colorimetric variations due to such a treatment are presented in table 11.

As further on in the text, these variations are expressed by the quantity ΔΕ * (which corresponds to the square root of the sum of the squares of the differences in chromatic values ​​L * a * b * before and after annealing). The index t, v, or c corresponds respectively to the transmission, the reflection on the glass side and the reflection on the layer side. Table 11

<img file="WO2011030049A2_D0011.tif" />

The comparative sample has a very strong deterioration in appearance, in particular in reflection on the layer side, while the sample according to the invention does not see its optical properties modified.

The samples also underwent the BSN test (resistance to Neutral Salt Fog) described in Annex D of standard EN 1096-2: 2001. The colorimetric variation in reflection, glass side and layer side is indicated in Table 12.

Table 12

C3 8

ΔΕ *_ν 3,7 0,1

ΔΕ *_α 33, 4 0.7 Here again, the comparative sample has a very strong change in appearance, unlike the sample according to the invention.

The excellent climatic durability conferred by the photocatalytic layer makes it possible to use the solar control glazing on face 1, therefore by presenting the stack of layers towards the exterior of the building.

In addition, Example 8 has a normal emissivity within the meaning of standard EN 12898 of 0.2, whether before or after quenching. This low emissivity makes it possible to limit the cooling of the exterior surface of the glazing during the night and consequently to obtain an effect of reduction or elimination of the condensation (fogging and / or frost) when the stack is placed opposite 1 of the glazing. This effect is particularly marked in the case of inclined double glazing, for example on roofs or verandas.

4^eme series of examples

Table 13 shows the composition and thickness of Examples 9 to 12. The stacking is carried out in the order of the table, the first line corresponding to the layer furthest from the substrate and the last line to that in contact with the substrate. As in the rest of the description, the thicknesses are physical thicknesses expressed in nm. Table 13

<img file="WO2011030049A2_D0012.tif" />

Table 14 summarizes the colorimetric and energy properties of Examples 9 and 10. The terms "TE", "RE", "g" correspond respectively to energy transmission, energy reflection and the solar factor within the meaning of standard NF EN 410: 1998.

Table 14

<img file="WO2011030049A2_D0013.tif" />

The stacks 9 and 10 have a particularly neutral color in reflection on the layer side.

The optical properties of examples 11 and 12 can be found in table 15. The value ΔΕ * here corresponds to the variation in color in reflection on the layer side due to a variation in thickness of +/- 10% in relative of the layer of Si02. Table 15

<img file="WO2011030049A2_D0014.tif" />

It appears from the comparison of the values ​​of ΔΕ * that the positioning of the layer of silica in contact with the glass substrate makes it possible to minimize the variations in shade in reflection due to possible variations in thickness of this same layer of silica. On the contrary, when the silica layer is placed under the photocatalytic layer, any change in its thickness results in a significant shade variation.