WO2024141515A1 - Glazing with low emissivity coating and color control - Google Patents

Abstract

The present invention falls in the field of glazing and, more particularly, it relates to low-emissivity coatings and preferably automotive glazing, such as automotive roof, with low-emissivity capabilities. The invention also relates to a method for manufacturing such glazing with low-emissivity capabilities.

Description

GLAZING WITH LOW EMISSIVITY COATING AND COLOR CONTROL

DESCRIPTION

FIELD OF THE INVENTION

The present invention falls in the field of glazing and, more particularly, it relates to low- emissivity coatings and preferably automotive glazing, such as automotive roofs, with low-emissivity capabilities. The invention also relates to a method for manufacturing such glazing with low-emissivity capabilities.

BACKGROUND OF THE INVENTION

Low-emissivity coatings, abbreviated ‘low-E’, are commonly known in the state of the art. Historically, the term ‘low-E’ has been used interchangeably for two types of coatings. First, in the architectural glass industry, this term is typically applied to solar-control (usually, silver-inclusive) coatings, while in the automotive glazing, ‘low-E’ typically implies a highly electrically conductive coating on the inner surface of the glass roof serving to prevent the absorption and consequent re-radiation of the heat energy from the environment on hot days into the passenger compartment. The more energy is transferred, the more fuel must be spent to keep the air conditioner working to provide passengers’ comfort. Besides, an automotive roof without a low-E coating can absorb sufficient solar radiation to get very hot on touch.

In winter, the situation is the opposite: automotive roofs with a higher emissivity lose more heat energy to the cold environment (outside the vehicle), thus putting more load on the vehicle's heater to keep passengers warm.

There is a steadily growing segment for opaque glazing with strict requirements for thermal insulation. Examples include automotive roofs with zero- or next-to-zero visible transmission (such as roofs with laminated photovoltaic panels, colored non-transparent roofs, etc.), opaque decorative architectural facades, etc.

Thermally insulating glazing employ two primary physical phenomena which can simultaneously be used in the same glazing:

1) Reflectance of near-IR portion of solar light using so-called solar control coatings, such as silver-based. These types of coatings are usually applied on surface 2 of the laminate in automotive windshields or roofs or on the inner surface of an architectural integrated glass unit. In a particular case of a laminated glazing having a first and a second glass layer, the first glass layer has an outer surface, also denoted surface 1 , and an inner surface, also denoted surface 2, wherein the inner surface of the first glass layer is facing the inner surface of the second glass layer. Furthermore, the inner surface of the second glass layer is denoted surface 3 and the outer surface of the second glass layer, also denoted surface 4, is facing towards the side where the first glass layer is not located. In automotive applications, surface 4 is the innermost surface of the glazing, i.e. the surface of the glass layer intended to face the interior of the vehicle in the operating position of the glazing.

2) Reflectance of mid-IR portion of the solar spectrum to prevent it from being reradiated by the glazing. This coating is called low-emissivity (Low-E) coating and is applied on the innermost surface of the glazing, thus preventing heat transfer by means of a combination of conduction and radiation, thus preventing heat energy absorption and subsequent re-radiation.

Traditional Low-E coatings used in automotive roofs use a layer of indium-tin-oxide (ITO), a transparent conductive oxide (TOO) with a sufficiently low sheet resistance to enable a low emissivity and, at the same time, be sufficiently transparent to provide daylight coming through the roof into the vehicle interior. The ITO, which is also a mechanically robust coating, is sandwiched between at least two dielectric layers serving as a blocker against sodium diffusion from the glass and as top scratch protection layer.

Emissivity (E) is a measure of how much thermal radiation a body, such as an automotive glass roof, emits to its environment. This characteristic is unitless and ranges between 0 and 1. It is proportionate to sheet resistance of a low-E coating. The lower the sheet resistance, the lower emissivity of the roof can be achieved. Emissivity with values less than 0.3, and more preferably lower than 0.2, are preferred for automotive roofs.

In a typical manufacturing cycle, a low-E coating is deposited by means of e.g. magnetron sputtering, on a surface of a predominantly flat glass pane (this surface becomes surface 4 of the glazing after the lamination).

ITO requires post-deposition activation for its crystallization to attain high levels of both electrical conductivity and optical transmission. The activation is usually achieved as a stand-alone thermal-assisted step or/and during high-temperature bending which is required to curve each of the two glass panes, including the ITO-coated one, to a desired shape before their lamination together by means of thermoplastic bonding layer, such as PVB. The lamination is done in such a way as to leave the low-E coating on surface 4 of the glazing after the lamination. Besides the layer of crystalline ITO, low-E coatings usually have an incorporated anti-reflective member consisting of a combination of several dielectric layers. The ITO is sandwiched between these layers. Layer thicknesses are adjusted according to optical simulation of the entire thin-film stack.

Recently, one of the modern automotive trends is to use more ‘aggressive’ shapes of glazing with reduced curvature radii of glass. This is done for both a better aesthetics and to improve aerodynamic characteristics of the vehicle. However, polycrystalline layers such as crystalline ITO for low-E coatings has the disadvantage of being cracked when it undergoes high-temperature bending to ‘aggressive’ shapes. This is caused by the fact that the ITO quickly crystallizes at high temperature and becomes brittle when bent. Bending the constituents of a low-E coating, especially brittle polycrystalline layers such as ITO, to such ‘aggressive’ 3D shapes.

Therefore, there is a need in the art for a low-E coating capable of being disposed on already bent (i.e. 3D shape) glass surface with reduced radius of curvature of glass or even a completed laminated glazing without the risk of cracking. It would also be desirable to avoid post-deposition heat activation (required for known low-E coating based on ITO) of such a coating applied on a glazing.

There is also a need in the art for glazing having said low-E coating, wherein the glazing is suitable for being installed in a vehicle.

Finally, there is also a need in the art for a method for manufacturing such glazing having the low-E coating with the aforementioned needs. DESCRIPTION OF THE INVENTION

The present invention provides a solution for the above-mentioned issues by a low- emissivity coating according to independent claim 1 , a glazing with low-emissivity capabilities according to claim 13, and a method for manufacturing a glazing with low- emissivity capabilities according to claim 14. In dependent claims, preferred embodiments of the invention are defined.

In a first inventive aspect, the present invention provides a coating comprising: a first electrically conductive layer; a first phase-control layer; and a second electrically conductive layer, wherein the first phase-control layer is disposed between the first and the second electrically conductive layer; wherein the first electrically conductive layer: is a metal or metal alloy, and has a physical thickness of less than or equal to 100 nm, preferably less than or equal to 40 nm; wherein the first phase-control layer: has an optical thickness that shifts % wavelength the phase of a light wave passing through the first phase-control layer, and has a refractive index of at least 2.0 at a wavelength reference of 550 nm; and wherein the second electrically conductive layer: has a physical thickness less than the physical thickness of the first electrically conductive layer; and wherein the coating has a sheet resistance less than 100, preferably less than or equal to 40 Q/sq.

The coating according to the invention is a low-emissivity coating which allows, among other options, to be disposed on already bent (i.e. 3D shape) glass surface with reduced radius of curvature of glass or even on a completed laminated glazing without the risk of cracking. The coating can also be deposited on a flat glass and then bent to a required shape.

Furthermore, this coating has the further advantage that, unlike ITO-based low-E coating, it does not require post-deposition heat activation when applied on a glass layer to form a glazing.

The first phase-control layer has these combined features: has an optical thickness that shifts % wavelength the phase of a light wave passing through the first phase-control layer, and has a refractive index of at least 2.0 at a wavelength reference of 550 nm.

The coating operates in such a way that when a light wave coming from the interior side of the glazing (i.e. in automotive applications, the interior side corresponds to the side facing the interior of the vehicle in the operating position of the glazing) is incident to the coating, the light wave firstly interacts the top layer of the coating, which is the second electrically conductive layer. Part of the light wave (R2) is reflected backwards from the second electrically conductive layer and another part of the light wave goes through the second electrically conductive layer and also through the first phase-control layer until it reaches the first electrically conductive layer. The optical thickness of the first phase control layer is in the same order of magnitude, preferably within ± 70 % of a quarter wavelength of the optical thickness of the material it is made of at a reference wavelength of 550 nm of incident light. Preferably, the optical thickness of the first phase control layer is of a quarter wavelength of the optical thickness of the material it is made of at a reference wavelength of 550 nm of incident light. In the case when the thickness of the first phase-control layer is exactly a quarter wavelength optical thickness of the material it is made of, the light wave that goes through the first phase-control layer has its phase shifted by 180 degrees. (. Part of the light wave that is incident the first electrically conductive layer is reflected (R1) backwards from the first electrically conductive layer. Therefore, the reflected light wave (R1) and (R2) are phase shifted 180 degrees from each other.

The refractive index of the first phase-control layer is at least 1 .95, and preferably at least 2.0 at a wavelength reference of 550 nm. Due to these combined features of the first phase-control layer along with the rest of layers of the coating, the first light wave (R1) reflected from the first electrically conductive layer and the second light wave (R2) reflected from the second electrically conductive layer are phase shifted 180 degrees between them, so the first and second reflections (R1 , R2) of a light wave which impacts the coating are cancelled out due to destructive optical interference. When two optical waves come together, they interact, and their amplitudes may either be added - if, e.g., the crests of the ways align, or subtracted from each other. In the latter case, if the crests are shifted to be completely out phase, the interference is called destructive, and if the amplitudes are equal in values, the waves will cancel each other. The total intensity in this case comes to zero. In optical terms, this means no reflection. Destructive optical interference allows to counteract high reflectivity of the first and second electrically conductive layer. The emissivity control is provided by the first and second electrically conductive layers, whereas the provision of the first phase-control layer in combination with the electrically conductive layers provides a reflectivity control. This means that, the first phase-control layer also has an additional effect of allowing the interior reflectance of the coating to be minimised, thus achieving a low interior reflectance.

Furthermore, the provision of a metallic material in the first electrically conductive layer permits to have a comparable or lower sheet resistance than a traditional ITO layer, which is one of the objectives for, for example, low-E automotive roofs.

The following terminology is used throughout the whole document to describe features of the invention.

The term “layer”, as used in this context, shall include the common definition of the word, i.e.: a sheet, quantity, or thickness, of material, typically of some homogeneous substance.

The term “index of refraction”, “refractive index” (or “refraction index”), or its acronym “Rl” are synonyms and may be used interchangeably. It should be understood as a dimensionless number that gives the indication of the light bending ability of that medium (i.e. the material). The refractive index determines how much the path of light is bent, or refracted, when entering a material. The refractive index may vary with wavelength. This causes white light to split into its constituent colors when refracted. This is called dispersion. Light propagation in absorbing materials can be described using a complex-valued refractive index. The imaginary part then handles the attenuation, while the real part accounts for refraction. For most materials the refractive index changes with wavelength by several percent across the visible spectrum. Refractive indices for materials are commonly reported using a single value, for example measured at 633 nm or at 550 nm. In the case of the present invention, the refractive index of the layer of the first phase-control layer is measured at a wavelength reference of 550 nm.

As has already been mentioned, the term “emissivity” or its acronym “E” is a measure of how much thermal radiation a material's surface, such as an automotive glass roof, emits to its environment. Thermal radiation is electromagnetic radiation that may include both visible radiation (light) and infrared radiation, which is not visible to human eyes. The thermal radiation from very hot objects is easily visible to the eye. Quantitatively, emissivity is the ratio of the thermal radiation from a surface to the radiation from an ideal black surface at the same temperature as given by the Stefan-Boltzmann law. This characteristic is unitless and ranges between 0 and 1. It is proportionate to sheet resistance of a low-E coating. The lower the sheet resistance, the lower emissivity of the roof can be achieved. A low-E should be understood as below or equal to 0.3; and preferably below or equal to 0.2.

The term “optical thickness” means the geometric thickness of the material multiplied by the refractive index of the material at a reference wavelength of 550 nm. For example, a material having a geometric thickness (also called physical thickness) of 5 nm and a refractive index of 2.0 at a reference wavelength of 550 nm would have an optical thickness of 10 nm.

Thickness values, unless indicated to the contrary, are geometric thickness values.

The term “glass substrate” or “glass pane” should be understood as a sheet, quantity, or thickness of material, typically of some homogeneous substance. The “glass substrate or pane” may comprise one or more layers. The glass substrate can be, for example, clear float glass or it can be tinted or colored glass. The glass substrate can be of any desired dimension, e.g., length, width, shape, or thickness.

The terms “glass pane” and “laminated glass pane” refer respectively to a glazing having one glass layer and to a laminated glazing having at least two glass layers respectively.

“Laminates”, in general, are products comprised of multiple sheets of thin, relative to their length and width, material, with each thin sheet having two oppositely disposed major faces and typically of a relatively uniform thickness, which are permanently bonded to each other across at least one major face of each sheet.

The term “stack” refers to the arrangement in a pile manner of a plurality of layers. When describing the coating stack, the convention of numbering the coating layers in the order of deposition upon the glass substrate should be used.

Also, throughout this document, when two layers of the coating are described, the one which is the closest to the substrate shall be referred to the bottom layer or the first layer and the subsequent layers shall be referred to second layer, and so on. Likewise, the top layer is the very last layer applied to the coating stack.

As for one individual layer of the coating, the top of an individual layer has to be understood as the side of the layer furthest from the substrate while the bottom has to be understood as the side of the layer which is either in contact with the substrate or oriented towards the substrate in case this layer is not the first layer of the coating stack.

With respect to a second layer located on a first layer in the coating, the term “on” should be understood as including both the option of the first and second layers being in direct contact (i.e. physical contact) and the option of having one or more additional layers located between the first layer and the second layer.

The term “glass” can be applied to many organic and inorganic materials, including many that are not transparent. From a scientific standpoint, “glass” is defined as a state of matter comprising a non-crystalline amorphous solid that lacks the long-range ordered molecular structure of true solids. Glasses have the mechanical rigidity of crystals with the random structure of liquids.

The term “glazing” should be understood as a product comprised of at least one layer of a transparent material, preferably glass, which serves to provide for the transmission of light and/or to provide for viewing of the side opposite to the viewer and which is mounted in an opening in a building, vehicle, wall or roof or other framing member or enclosure.

Among the elements of a valuable appearance is the color of for example a vehicle roof laminate. Color can be described mathematically. Cl ELAB is one of the many color spaces and is normally used in automotive and architectural industries. The advantage of the Cl ELAB is that color shifts on the Cl ELAB diagram are perceived proportionally by the human eye. The Cl ELAB L*, a*, b* color space mathematically describes all perceivable colors in three dimensions: L* for perceptual lightness, a* for green-red, and b* for blue-yellow. See Hunter Lab, Applications Note, "Insight on Color," Vol. 8, No. 7 (2008). In the CIELAB color space, the L* axis runs from top to bottom. The maximum L* value is 100, which indicates a perfect reflecting diffuser (i.e., the lightest white). The minimum L* value is 0, which indicates a perfect absorber (i.e., the darkest black). Positive a* is red. Negative a* is green. Positive b* is yellow. Negative b* is blue. CIELAB a* or b* values equal to 0 indicate no red-green or blue-yellow color appearance, in which case the article would appear pure white. In contrast, a* or b* values that deviate far from 0 indicate that light is non-uniformly absorbed or reflected. As a* or b* values deviate from 0, the color may no longer appear as bright white. One of the most important attributes of the CIELAB model is device independence, which means that the colors are defined independent of their nature of creation or the device they are displayed on.

The L*, a*, and b* values of the CIELAB color scale can be obtained using any CIELAB color measurement instrument and are calculated from known formulas. See Hunter Lab, Applications Note, "Insight on Color," Vol. 8, No. 7 (2008).

Thus, the uniqueness of the CIELAB space is in its perceived uniformity. A change in the numerical difference between two color coordinates is proportionate difference in color perceived by the eye.

The terms “metal” and “metal alloy” include the traditionally recognized metals and metal alloys. Silicon and silica are non-metallic materials. By saying that the first electrically conductive layer is a metal or metal alloy it follows that the first electrically conducting layer cannot be an ITO. Due to the fact that an ITO is a n-type semiconductor with a large bandgap of around 4 eV, it is not strictly metallic. When a range is of values is provided in the application, it should be understood that the two limiting values of the range are also included. For example, if a range of 20 to 100 nm is provided, the values 20 and 100 nm are also included within the range.

In an embodiment, the preferred range of the physical thickness of the first electrically conductive layer is from 5 to 100 nm.

The fact that the second electrically conductive layer has a physical thickness less than the thickness of the first electrically conductive layer allows to create a second reflective wave which, when combined with the reflective wave from the thicker reflective layer, advantageously creates destructive optical interference which cancels out the total reflection.

In a particular embodiment, the second electrically conductive layer has a physical thickness in a range between 10 and 80% the thickness of the first electrically conductive layer, preferably in a range between 20 and 60% the thickness of the first electrically conductive layer, and more preferably in a range between 30 and 40% the thickness of the first electrically conductive layer. Thus, for example, if the physical thickness of the first electrically conductive layer is 10 nm, the physical thickness of the second electrically conductive layer is in the range of 1 to 8 nm.

In an embodiment, the coating of the present invention only comprises these layers: the first electrically conductive layer; the first phase-control layer; and the second electrically conductive layer.

In a preferred embodiment, the first phase-control layer has a refractive index from 2.0 to around 4.0 at a wavelength reference of 550 nm. In a more preferred embodiment, the first phase-control layer has a refractive index from 2.0 to around 4.0 at a wavelength reference of 550 nm.

In an embodiment, the coating is disposed on a glass substrate. In another embodiment, the coating of the present invention further comprises, apart from the first phase-control layer, the first electrically conductive layer and the second electrically conductive layer: a second phase-control layer disposed on the second electrically conductive layer.

Said second phase-control layer has the same characteristics as the first phase-control layer, i.e. the second phase-control layer: has an optical thickness that shifts % wavelength the phase of a light wave passing through the first phase-control layer, and has a refractive index of at least 2.0 at a wavelength reference of 550 nm.

In an embodiment, the coating comprises a third electrically conductive layer disposed on the second phase-control layer, wherein the combined thickness of the second and third electrically conductive layers is smaller compared to the thickness of the first electrically conductive layer. The combined thickness of the second and third electrically conductive layers should be understood as the sum of the thicknesses of both layers.

In a preferred embodiment, the first electrically conductive layer and the first phasecontrol layer of the coating of the present invention are in physical contact with each other, and the first phase-control layer and the second electrically conductive layer are also in physical contact with each other.

In an alternative embodiment, the first electrically conductive layer of the coating of the present invention is separated from the first phase-control layer by an intermediate layer; and the first phase-control layer is in physical contact with the second electrically conductive layer.

In an embodiment of the coating having a second phase-control layer disposed on the second electrically conductive layer and a third electrically conductive layer.

In some embodiments, at least one of the first and second phase-control layer of the coating comprise a non-metallic material, such as a dielectric or a semiconductor material. Therefore, the first or the second phase-control layer or both is/are a dielectric layer or a semiconductor layer.

In some embodiments of the coating, the phase-control layer or layers can comprise a single material. Alternatively, the phase-control layer/s can comprise multiple materials and/or multiple films. The phase-control layers can comprise a stratified sequence of films of chemically distinct materials or phases or may comprise one or more composites of one or more chemically distinct materials or phases. The different phase-control layers can comprise the same or different materials. The phase-control layers can have the same or different thicknesses.

Examples of suitable materials for the first and/or second phase-control layers include: NiCrOx, CrOx, CrOxSi, TiOx, ZrOx, AITiOx, ZrSiOx, ZrTiOx and NbOx.

In one preferred embodiment, the first phase-control layer disposed between the two electrically conductive layers is NiCrOx with the extinction coefficient and thickness tuned in such a way as to attain the intensity of the light wave reflected from the second electrically conductive layer (at the reference wavelength of 550 nm) be 35% of that reflected from the first electrically conductive layer. The extinction coefficient determines how strongly a material absorbs or reflects light. It is often written as lm(ni) - the imaginary part of the complex refractive index and is used along with the Re(ni) - the real part of the complex refractive index - as a set of optical constants specific for each material.

The first (and optionally second) phase-control layers allow adjustment of the constructive and destructive optical interference of electromagnetic radiation partially reflected from, or partially transmitted by, the various interface boundaries of the layers of the low emissivity coating. Varying the thicknesses and/or compositions of at least the first phase-control layer may change the overall reflectance, transmittance, and/or absorptance of the low emissivity coating, which can alter the solar control performance, thermal infrared insulating performance, color, and/or aesthetics of the low emissivity coating. Additionally, at least the first phase-control layer provides chemical and/or mechanical protection for other layers of the low emissivity coating, such as the first and second electrically conductive layers. In a preferred embodiment, the second electrically conductive layer is a metal or a metal alloy. By saying that the second electrically conductive layer is a metal or metal alloy it follows that the second electrically conducting layer cannot be an ITO. Due to the fact that an ITO is a n-type semiconductor with a large bandgap of a range comprised between 3.8 and 4.2 eV, it is not strictly metallic.

In a particular embodiment, the first, second and/or optional third electrically conductive layer comprises a layer which is: a Ni-based layer, a Cr-based layer, an Inconel-based layer, or a Ti-based layer or a combination thereof. Inconel is a family of alloys of Ni, Or, Fe, and other elements in different proportions. In a preferred embodiment, the first, second and/or optional third electrically conductive layer is a layer of NiCr. This means that the first electrically conductive layer is NiCr, or the second electrically conductive layer or the optional third electrically conductive layer is NiCr or all electrically conductive layers are NiCr.

In a particular embodiment, both the first and second electrically conductive layers comprise: a Ni-based layer, a Cr-based layer, an Inconel-based layer, or a Ti-based layer or a combination thereof. In a preferred embodiment, both the first and second electrically conductive layers are a layer of NiCr.

In another particular embodiment, all the electrically conductive layers (first, second, third, and/or other electrically conductive layers) comprise: a Ni-based layer, a Cr-based layer, an Inconel-based layer, or a Ti-based layer or a combination thereof.

In a particular embodiment, the first electrically conductive layer has a physical thickness comprised in the range between 20 and 100 nm.

In a particular embodiment, the second and/or the optional third electrically conductive layer has a physical thickness comprised in the range between 2 and 20 nm, preferably between 2 and 15 nm.

In some embodiments, further phase control layer/s and "thin" electrically conductive layer/s, such as the second or third electrically conductive layer, can be also included. In a particular embodiment, the first phase-control layer has a physical thickness comprised in the range between 20 and 120 nm, preferably between 30 and 90 nm, and more preferably between 50 and 80 nm.

In a particular embodiment, the coating further comprises a bottom dielectric barrier layer disposed on the free side of the first electrically conductive layer, so that the first electrically conductive layer is located between the bottom dielectric barrier layer and the first phase-control layer. Preferably, the bottom dielectric barrier layer comprises a Si- based dielectric layer, preferably based on a compound selected from SiOxNy, SiNx, or a combination of these two compounds. The silicon-based bottom dielectric advantageously acts as a Na diffusion blocking layer. In a particular embodiment, the bottom dielectric barrier layer has a physical thickness comprised in a range between 5 and 70 nm.

In a particular embodiment, the coating further comprises at least one anti-reflective layer disposed on the second electrically conductive layer or on the third electrically conductive layer. The anti-reflective layer serves to minimize the interior reflection in the visible part of the spectrum as well as to optimize the reflected color.

In a particular embodiment of the coating which includes at least one anti-reflective layer, preferably the at least one anti-reflective layer comprises either: a single layer of SiOx, or a combination of at least two adjacent dielectric layers, wherein the at least two adjacent dielectric layers have alternating high and low refractive indices, wherein the at least two adjacent dielectric layers comprises a first dielectric layer, preferably a NbOx anti-reflective layer, and a second dielectric layer, preferably a SiOx anti-reflective layer, and wherein the first dielectric layer is disposed between the second dielectric layer and the second electrically conductive layer. The NbOx layer has a “high refractive index”, while the SiOx layer a “low index of refraction”. In the present application, a “high index of refraction” is considered equal or above 1.8 and “low refractive index” equal or below 1 .6 measured at a wavelength reference of 550 nm. In a first particular example where the at least one anti-reflective layer of the coating is composed of a single layer of SiOx, the single layer of SiOx has a physical thickness comprised in a range between 10 and 120 nm and preferably between 30 and 100 nm, and more preferably between 50 and 80 nm.

In a second particular example, the at least one anti-reflective layer of the coating is composed of a single thicker layer of SiOx with a physical thickness comprised in a range between 90 and 140 nm and preferably between 100 and 115 nm.

In a third particular example, the at least one anti-reflective layer of the coating is composed of a combination of two adjacent dielectric layers: a first NbOx and a second SiOx anti-reflective layer, wherein the first NbOx anti-reflective layer has a physical thickness comprised in a range between 10 and 25 nm; and/or the second SiOx anti- reflective layer has a physical thickness comprised in a range between 10 and 120 nm.

In some embodiments, more than two adjacent dielectric layers may be included in the at least one anti-reflective layer, wherein each adjacent dielectric layer has alternating high and low refractive indices. For example, a possible example may be a tetra layer of NbOx first layer plus SiOx layer plus NbOx layer plus SiOx layer.

In some embodiments, the coating may comprise an ITO layer disposed between the first electrically conductive layer and the first phase-control layer, wherein the ITO layer has a physical thickness comprised in the range between 40 and 80 nm. Due to the fact that an ITO is a TOO (transparent conductive oxide) it has the function of helping to improve solar control of the coating. Furthermore, the optional ITO layer is an additional conductive layer which advantageously contributes to lowering the total emissivity. In this case, the at least one first phase-control layer can accommodate ITO (or IZO, AZO, etc.), thinner than used now to optimize emissivity, reflectance, and reflected color.

In some embodiments, the layers of the coating are continuous layers.

When it is mentioned that the coating has a sheet resistance less than 100 Q/sq, preferably less than or equal to 40 Q/sq, it is to be understood as having a total sheet resistance of the complete coating stack. Other layers than the first and second electrically conductive layers (such as conductive oxides) that may be present in the coating stack also contribute to total sheet resistance of the coating stack.

Preferably, the coating defined in any one of the preceding embodiments has a sheet resistance less than 100 Q/sq, preferably less than or equal to 40 Q/sq, more preferably less than 30 Q/sq, and even more preferably less than 20 Q/sq.

Preferably, the coating defined in any one of the preceding embodiments has an emissivity less than 0.3, preferably less than 0.2, and more preferably less than 0.1.

In an alternative first inventive aspect, the present invention provides a coating comprising: a first electrically conductive layer; a first phase-control layer; and a second electrically conductive layer, wherein the first phase-control layer is disposed between the first and the second electrically conductive layer; wherein the first electrically conductive layer: is a metal or metal alloy, and has a physical thickness of less than or equal to 100 nm, preferably less than or equal to 40 nm; wherein the first phase-control layer: has an optical thickness that shifts wavelength the phase of a light wave passing through the first phase-control layer, and has a refractive index of at least 1.95 at a wavelength reference of 550 nm; and wherein the second electrically conductive layer: has a physical thickness less than the physical thickness of the first electrically conductive layer; and wherein the coating has a sheet resistance less than 100, preferably less than or equal to 40 Q/sq.

All described features disclosed for the first inventive aspect apply to the alternative first inventive aspect. In a second inventive aspect, the present invention provides a glazing with low-emissivity capabilities, comprising: at least one glass layer having an outer surface and an inner surface, wherein the outer surface is opposite to the inner surface, and a coating according to any of the previous defined embodiments disposed on at least one portion of the inner or outer surface of the at least one glass layer, wherein: the first electrically conductive layer is disposed between the inner or outer surface of the at least one glass layer and the first phase-control layer; or the first phase-control layer is disposed between the inner surface of the least one glass layer and the first electrically conductive layer.

The glazing of the present invention is intended for vehicles, and more particularly for automobiles (automotive roof) such as passenger cars.

When describing the coating stack, the convention of numbering the coating layers in the order of deposition upon the glass substrate should be used.

The at least one glass layer can be a single glass layer or a multiple glass layers.

In a first embodiment where the glazing has a single glass layer (so-called monolithic glazing), the single glass layer has two opposed major surfaces (or sides), an outer and an inner surface; and to comply with regulatory requirements, the single glass layer glazing is preferably tempered. In this first embodiment where the glazing has a single glass layer, the inner surface corresponds to the innermost surface of the glazing facing the interior of a vehicle in an automotive application and the outer surface corresponds to the outermost surface of the glazing facing the exterior.

In said first embodiment of the at least one glass layer having a single glass layer, the glazing with low-emissivity capabilities, comprises: a single glass layer having two opposed major surfaces (or sides), an outer and an inner surface, and a coating according to any of the embodiments of the first inventive aspect disposed on at least one portion of the inner surface of the single glass layer, wherein the first electrically conductive layer is disposed between the inner surface of the single glass layer and the first phase-control layer.

In a second embodiment of the at least one glass layer, it is a laminate, which is configured by at least two glass layers, namely a first glass layer, a second glass layer and a bonding layer disposed between the first and the second glass layer. In this second embodiment of the at least one glass layer, the bonding layer, such as a thermoplastic interlayer (e.g., PVB), has the primary function of bonding the major faces of adjacent glass layers to each other. These major faces of the at least first and second glass layers can also be called inner surfaces of the first glass layer and the second glass layer, respectively. In other words, the inner surface of the first glass layer is bonded with the inner surface of the second glass layer.

In this second embodiment where the glazing has more than one glass layer, i.e., multiple glass layers, to comply with regulatory requirements, the multiple layer glazing is preferably laminated.

In this particular case of a laminated glazing having two glass layers, a first and a second glass layer, the first glass layer has an outer surface, also denoted surface 1 , and an inner surface, also denoted surface 2, wherein the inner surface of the first glass layer is facing the inner surface of the second glass layer. Furthermore, the inner surface of the second glass layer is denoted surface 3 and the outer surface of the second glass layer (also being the interior surface of the glazing), also denoted surface 4, is facing towards the side where the first glass layer is not located.

In a particular case of the second embodiment of the at least one glass layer being a laminate having two glass layers, the glazing with low-emissivity capabilities, comprises: two glass layers having two outer surfaces and two inner surfaces, and a coating according to any of the embodiments of the first inventive aspect disposed on at least one portion of the inner surface of the second glass layer (surface 3) or the outer surface of the second glass layer (surface 4), wherein: when the coating is disposed on at least one portion of outer surface of the second glass layer (surface 4), the first electrically conductive layer is disposed between the outer surface of the second glass layer (surface 4) of the at least one glass layer and the first phase-control layer; and when the coating is disposed on at least one portion of the inner surface of the second glass layer (surface 3), the first phase-control layer is disposed between the inner surface of the second glass layer (surface 3) and the first electrically conductive layer.

In said particular case of the second embodiment of the at least one glass layer being a laminate with two glass layers, once the coating is disposed on at least one portion of the inner surface of the second glass layer (surface 3) or the outer surface of the second glass layer (surface 4), the first and second glass layers are laminated positioning the bonding layer in contact with both the inner surfaces (surfaces 2 and 3) of the respective two glass layers.

In an embodiment, the coating according to the embodiment of the first inventive aspect is disposed on at least one portion of the inner surface of the second glass layer (surface 3) or the outer surface of the second glass layer (surface 4), so that there is a physical contact between one of the first or second electrically conductive layer of the coating and one glass layer. However, in other embodiment, when a bottom dielectric barrier layer is provided in the coating stack, the coating is disposed on at least one portion of the inner surface of the second glass layer (surface 3) or the outer surface of the second glass layer (surface 4), so the first electrically conductive layer is located between the bottom dielectric layer and the first phase-control layer, so that any of the first or second electrically conductive layers of the coating according to the embodiment of the first inventive aspect is in physical contact with one glass layer.

In an embodiment, the type of glass for the at least one glass layer or for both glass layers of a laminate that may be used include, but are not limited to, common soda-lime variety typical of automotive glazing as well as aluminosilicate, lithium aluminosilicate, borosilicate, glass ceramics, and various other inorganic solid amorphous compositions which undergo a glass transition and are classified as glass including those that are not transparent. Preferably, the thickness of the at least one glass layer may vary widely and thus be ideally adapted to the requirements of the individual cases. In an embodiment, the thickness of the at least one glass layer of the glazing of the invention is lower than 5.0 mm, preferably comprised between 0.3 mm and 5.0 mm, such as between 0.5 mm and 4.0 mm or between 1.0 mm and 3.0 mm. Possible examples of thicknesses of the at least one glass layer are about 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm or 3.0 mm. More preferably, the glass layer is about 2.1 mm thick soda-lime glass layer, including ultra-clear, clear or green soda-lime.

Preferably, the material selected for the bonding layer is a clear thermoset plastic, also called polyvinyl butyral or PVB. Additionally, ethylene vinyl acetate (EVA) or thermoplastic polyurethane (TPU) may be used as bonding layers.

Additional embodiments of the present invention may include a plastic interlayer made of tinted PVB. Tinted PVB interlayers may have different levels of light transmission and can be of different thicknesses. Preferably, the thickness of the plastic bonding layer, clear or tinted is comprised between 0.3 mm and 2.0 mm, such as between 0.5 mm and 1.0 mm, e.g. about 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1.0 mm. Particular thicknesses for the plastic bonding layer, e.g. a - tinted - PVB interlayer, are for instance 0.38 mm, 0.631 mm and 0.76 mm.

In an embodiment, the PVB plastic interlayer is comprised of particles that absorb partially the infrared light of the sun. Preferably, the interlayer may have solar attenuating properties.

In the second embodiment of the glazing where the glazing has multiple glass layers, said glazing is preferably laminated.

In the second embodiment of the glazing with two glass layers, the coating can be located on the outer surface of the second glass layer (i.e., the so-called surface 4). In the embodiment where the coating is located on the outer surface of the second glass layer (surface 4), the two glass layers are laminated positioning the bonding layer in contact with both the inner surfaces (surfaces 2 and 3) of the respective glass layers. In this first position, the glazing achieves an optimum low-E.

Alternatively, the coating can be also located on the inner surface of the second glass layer (i.e. , the so-called surface 3).

In an embodiment of the glazing, where the coating is deposited on the at least one glass layer, the resulting product can be further bent. In another embodiment the glass can be bent firstly and then the coating being deposited on top.

In a particular embodiment, the at least one glass layer comprises two glass layers separated by at least one plastic bonding layer, thus resulting in a laminate, and further comprises a bottom dielectric barrier layer disposed on the bonding layer.

In a particular embodiment, the glazing further comprises at least one anti-reflective layer, wherein: a. when the coating is disposed on the inner surface of the at least one glass layer, the at least one anti-reflective layer is disposed on the outer surface of the second glass layer; and b. when the coating is disposed on the outer surface of the at least one glass layer, the at least one anti-reflective layer is disposed on the second electrically conductive layer.

In a particular embodiment, the glazing has an integrated interior reflectance R_vis in the visible region of the spectrum less than 10%, and preferably less than 5%. Advantageously, having the glazing with such a low interior reflectance minimizes visual distraction to the vehicle occupants.

Preferably, the glazing according to any of the defined embodiments has a reflection less than 10%, and preferable between 1.5 and 6%.

Some embodiments of the glazing have an outside reflected color (Cl ELAB) wherein: a* is between -5.0 and +1.0; and b* is between -2.0 and +7.0. In an embodiment, the glazing is a curved glazing. In a preferred embodiment, the curved glazing is one wherein the minimum curvature radius of it is less than or equal to 200 mm.

Preferably, the glazing according to any of the embodiments has a radius of curvature that infers to a complex shape or complex curvature.

In the context of the invention, to evaluate the complexity associated with the shape of a curved glass layer of the glazing, the inverse process of the bending process is considered. According to said inverse process, the glass layer is bent from target shape to flat. Thus, the inverse process is a flattening process. A finite element model can be implemented for the flattening process and solved by a structural non-linear solver such as Abaqus. The Maximal Compressive Strain (MCS) is defined herein as the maximal area strain that is generated on the mid-surface of the glass layer during the flattening process, that corresponds to the opposite (that is with a minus sign) of the minimal area strain for the bending process. For a point on the mid-surface, area strain corresponds to the sum of maximal and minimal in-plane principal components of the strain tensor for the same point. The finite element model is based on elastic properties of glass. Midsurface is formally defined as the imaginary surface that is equidistant from outer and inner surfaces of the glass layer.

In an embodiment, evaluation of the MCS value for an actual glass layer of the glazing can be made according to a method comprising the following steps:

(1) Scanning the glass layer surface to obtain a computer file including a cloud of points or a mesh that represents accurately the glass layer surface and size. Any surface of the glass layer may be scanned (i.e. any major surface of the glass layer), preferably a convex major surface of the glass layer, such as the surface intended to be an outer surface of the glazing when the glazing is in an operating position.

(2) Building a continuous surface that interpolates the cloud of points or mesh, for example using a CAD software. (3) Building a finite element mesh from the obtained surface, the finite element mesh comprising nodes and shell elements, for example triangular and/or quadrilateral shell elements, such as S3 and/or S4 elements in Abaqus. Preferably, the finite element mesh is fine enough for the MCS value to be unchanged if the mesh is further refined.

(4) Associating to the shell elements the elastic properties of glass. In an embodiment, the following properties are used: E-modulus = 70 Gpa and Poisson ratio = 0.22.

(5) Rotating the finite element mesh in a way that it be essentially horizontal in the initial state of the analysis.

(6) Defining a static non-linear analysis.

(7) Creating boundary conditions for z-coordinates that will displace each individual node from its original z-coordinate to z=0, wherein z-direction is perpendicular to the horizontal plane. No boundary conditions on x- and y-coordinates are defined, so the shape can unfold in a natural manner during the flattening process, without generating artificial strains. It is allowed to fix x- and y-coordinates for one single node in the center of the finite element mesh to constrain rigid body motion and help convergence.

(8) Running the static non-linear analysis.

(9) Building a field output that is defined as the sum of maximal and minimal in-plane principal strains. MCS value is the maximal value of this field output found in the midsurface of the glass layer.

In an embodiment, at least one glass layer of the glazing has a Maximal Compressive Strain (MCS) greater than 7.

In an embodiment, every glass layer of the glazing has a Maximal Compressive Strain (MCS) greater than 7. In an embodiment, the glazing has two glass layers and both glass layers have a Maximal Compressive Strain (MCS) greater than 7.

In an embodiment, the glazing is a laminated glazing for a vehicle, for example for a roof, a windshield or a sidelite of a vehicle. In another embodiment, the glazing is an architectural glazing.

In a third inventive aspect, the present invention provides a roof for a vehicle or similar, wherein the roof comprises at least one glazing according to any of the embodiments, or any suitable combination thereof, of the second inventive aspect of the invention. In a particular embodiment of the automotive roof, it comprises a laminated glazing having two or more bonded glass layers.

In a fourth inventive aspect, the present invention provides a vehicle, comprising at least one glazing according to any embodiment of the second inventive aspect.

The term “vehicle” in the present invention includes, but is not limited to, road vehicles (e.g. cars, busses, trucks, agricultural and construction vehicles, cabin motorbikes), railway vehicles (e.g. locomotives, coaches), aircraft (e.g. airplanes, helicopters), boats, ships and the like. For instance, the vehicle may be a road vehicle and more particularly a car.

In a fifth inventive aspect, the present invention provides a method for manufacturing a glazing according to any of the embodiments of the second inventive aspect, the method comprising the following steps: providing at least one glass layer having an outer surface and an inner surface, wherein the outer surface is opposite to the inner surface; providing a coating, wherein providing a coating comprises: depositing a first electrically conductive layer on at least a portion of the outer surface of the at least one glass layer or on at least one portion of the inner surface of the at least one glass layer, wherein the first electrically conductive layer: is a metal or metal alloy, and has a physical thickness of less than or equal to 100 nm, preferably less than or equal to 40 nm; depositing a first phase-control layer on at least a portion of said first electrically conductive layer, wherein the first phase-control layer: has an optical thickness that shifts % wavelength the phase of a light wave passing through the first phase-control layer, has a refractive index of at least 2.0, at the reference of 550 nm wavelength; depositing a second electrically conductive layer on said first phasecontrol layer, wherein the second electrically conductive layer: has a physical thickness less than the physical thickness of the first electrically conductive layer; wherein the sheet resistance of the coating is less than 100 Q/sq, preferably less than or equal to 40 Q/sq.

Preferably, the above steps of the method of manufacturing a glazing are performed in the order listed.

In an embodiment, the first phase-control layer has the following combined features: has an optical thickness that shifts % wavelength the phase of a light wave passing through the first phase-control layer, and has a refractive index of at least 2.0 at a wavelength reference of 550 nm.

The method for manufacturing a glazing may further comprise an additional step of depositing a second phase-control layer on at least a portion of the second electrically conductive layer and an additional step of depositing a third electrically conductive layer on at least a portion of the second phase-control layer. Preferably, these additional steps are performed at the end of the process, i.e., after the step depositing a second electrically conductive layer on said first phase-control layer.

The method for manufacturing a glazing may further comprise an additional step of depositing at least one anti-reflective layer on at least a portion of the second or third electrically conductive layer. Preferably, this additional step of depositing at least one anti-reflective layer in the glazing is performed at the end of the process, i.e., after the step depositing a second or third electrically conductive layer on said first phase-control layer.

Several different options of depositing the low-E coating on a surface of a glass layer, preferably by a sputter deposition at room temperature (RT) without post-deposition activation, are next described:

1. In a first option of the invention, the low-E coating according to any of the embodiments of the first inventive aspect is deposited on a fully bent glass layer and then is optionally laminated to a second (outermost) curved laminated glass pane.

2. In a second option of the invention, the low-E coating according to any of the embodiments of the first inventive aspect is deposited on a partially bent glass layer which then undergoes, if required, a second bending step, followed by an optional lamination to an outermost laminated glass pane.

3. In a third option of the invention, for some roof shapes, the low-E coating according to any of the embodiments of the first inventive aspect is deposited on a flat glass layer, followed by its optional bending and optional lamination.

4. In a fourth option of the invention, the low-E coating according to any of the embodiments of the first inventive aspect is deposited on a complete laminated glazing.

The coating according to the invention can be deposited on a fully bent glass layer (option 1).

According to the option 1 , in the method for manufacturing a glazing according to embodiments of the fifth inventive aspect: the at least one glass layer is a fully bent glass layer; the first electrically conductive layer is deposited on said fully bent glass layer; and the method optionally comprises a step of laminating the result of the method according to embodiments of the fifth inventive aspect to a laminated glass pane.

Therefore, according to option 1 , the method for manufacturing a glazing according to the present invention comprises the following steps: providing a fully bent glass layer having an inner and an outer surface; depositing the low-E coating according to any of the embodiments on the fully bent glass layer of the previous step; optionally (if required) laminating the result of the method to a second outermost laminated glass pane. The resulting laminated glass pane according to the option 1 will be a curved laminated glass pane, as the glass layer is a fully bent glass layer.

Preferably, the above steps of the method for manufacturing a glazing according to option 1 are performed in the order listed.

The coating according to the invention can also be deposited on a partially bent glass layer (option 2) or on a flat glass layer (option 3).

According to options 2 and 3, in the method for manufacturing a glazing according to embodiments of the fifth inventive aspect: the at least one glass layer provided is a partially bent glass layer or at least one flat glass layer; the first electrically conductive layer is deposited on said partially bent glass layer or on said flat glass layer; the method optionally comprises a step of performing a bending step onto the result of the method according to embodiments of the fifth inventive aspect to obtain a final curved shape; and the method optionally comprises a step of laminating the result of the method according to embodiments of the fifth inventive aspect to a laminated glass pane.

Therefore, according to option 2 and 3, the method for manufacturing a glazing according to the present invention comprises the following steps: providing a partially bent single glass layer or a flat single glass layer, wherein the glass layer has an inner and an outer surface; depositing the low-E coating according to any of the embodiments on the partially bent single glass layer or on the flat single glass layer of the previous step; optionally (if required) performing a bending step onto the result of the method to obtain a final curved shape; optionally (if required) laminating the result of the method to a second outermost laminated glass pane. Preferably, the above steps of the method according to option 2 or 3 are performed in the order listed.

In an embodiment, the deposition steps of depositing the low-E coating on a fully bent glass layer, on a partially bent glass layer or on a flat glass layer are preferably made by sputter deposition of the layers of the coating on a surface of at least one glass layer at room temperature without post-deposition activation of the coating. Advantageously, after the sputter deposition no post-deposition activation is required.

In an embodiment, the sputter deposition of the layers of the coating is made by magnetron sputtering deposition or alternatively by a reactive sputtering.

In an embodiment, the deposition of the layers of the coating is made by electron-beam deposition, ion-beam deposition, or chemical-vapor deposition (CVD), such as plasma- enhanced CVD.

In an alternative fifth inventive aspect, the present invention provides a method for manufacturing a glazing according to any of the embodiments of the second inventive aspect, the method comprising the following steps: providing at least one glass layer having an outer surface and an inner surface, wherein the outer surface is opposite to the inner surface; providing a coating, wherein providing a coating comprises: depositing a first electrically conductive layer on at least a portion of the outer surface of the at least one glass layer or on at least one portion of the inner surface of the at least one glass layer, wherein the first electrically conductive layer: is a metal or metal alloy, and has a physical thickness of less than or equal to 100 nm, preferably less than or equal to 40 nm; depositing a first phase-control layer on at least a portion of said first electrically conductive layer, wherein the first phase-control layer: has an optical thickness that shifts % wavelength the phase of a light wave passing through the first phase-control layer, has a refractive index of at least 1 .95 at the reference of 550 nm wavelength; depositing a second electrically conductive layer on said first phasecontrol layer, wherein the second electrically conductive layer: has a physical thickness less than the physical thickness of the first electrically conductive layer; wherein the sheet resistance of the coating is less than 100 Q/sq, preferably less than or equal to 40 Q/sq.

All described features disclosed for the fifth inventive aspect apply to the alternative fifth inventive aspect.

DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the invention will be seen more clearly from the following detailed description of preferred embodiments provided only by way of illustrative and non-limiting examples in reference to the attached drawings.

Figures 1 to 5 illustrate respective side views (not to scale) of a low-E coating (3) according to different embodiments of the present invention.

Figures 6 and 7 illustrate respective side views (not to scale) of a monolithic glazing (1) comprising a low-E coating (3) deposited on the inner surface (2.4.2) corresponding to the innermost surface of a single glass layer (2.4) according to different embodiments of the invention.

Figures 8 to 12 illustrate respective side views (not to scale) of a laminated glazing comprising a low-E coating (3) deposited on the outer surface (2.2.2) of the second glass layer (2.2) according to different embodiments of the invention.

Figures 13 and 14 illustrate respective side views (not to scale) of a laminated glazing comprising a low-E coating (3) deposited on the inner surface (2.2.1) of the second glass layer (2.2) according to different embodiments of the invention. Figures 15 and 16 illustrate the respective transmission and reflection spectra of the laminated glazing, embodied as a vehicle roof, of examples of Figure 9 and 11 , respectively, as seen from the exterior side.

DETAILED DESCRIPTION OF THE INVENTION

As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a product or method.

The present invention provides a low-E coating (3), comprising a first electrically conductive layer (3.2), a first phase-control layer (3.3.1) and a second electrically conductive layer (3.4.1), wherein the first phase-control layer (3.3.1) is disposed between the first (3.2) and the second (3.4.1) electrically conductive layer.

The first electrically conductive layer (3.2) is a metal or metal alloy and has a physical thickness of less than or equal to 100 nm. In a preferred embodiment the physical thickness is less than or equal to 40 nm.

The first phase-control layer (3.3.1) has a thickness in the same order of magnitude, preferably within ± 70 % of a quarter wavelength optical thickness of the material it is made of in reference to 550 nm of incident light, and has a refractive index of at least 1 .95, and preferably of at least 2.0 at a wavelength reference of 550 nm.

The second electrically conductive layer (3.4.1) has a physical thickness less than the physical thickness of the first electrically conductive layer (3.2).

The coating (3) has a sheet resistance less than 100 Q/sq, preferably less than or equal to40 Q/sq.

Different embodiments of a low-E coating of the present invention are shown in Figures 1 to 5.

Figure 1 depicts a low-E coating (3) according to an embodiment of the invention. In this embodiment, the low-E coating (3) comprises a first electrically conductive layer (3.2), a first phase-control layer (3.3.1) located on said first electrically conductive layer (3.2) and a second electrically conductive layer (3.4.1) located on said first phase-control layer

(3.3.1), wherein the thickness of the said second electrically conductive layer (3.4.1) is less than the thickness of the first electrically conductive layer (3.2).

In an embodiment, the first (3.2) and/or second (3.4.1) electrically conductive layer comprises a layer which is: a Ni-based layer, a Cr-based layer, an Inconel-based layer, or a Ti-based layer or a combination thereof.

In an embodiment, the first electrically conductive layer (3.2) has a physical thickness comprised in the range between 20 and 100 nm. In another embodiment the first electrically conductive layer (3.2) has a physical thickness comprised in the range between 20 and 40 nm

In an embodiment, the second electrically conductive layer (3.4.1) has a physical thickness comprised in the range between 2 and 20 nm.

In an embodiment, the first phase-control layer (3.3.1) is selected from the group consisting of: NiCrOx, CrOx, CrOxSi, TiOx, ZrOx, AITiOx, ZrSiOx, ZrTiOx and NbOx.

In an embodiment, the first phase-control layer (3.3.1) has a physical thickness comprised in the range between 20 and 120 nm.

Figure 2 depicts a low-E coating (3) according to another embodiment of the invention, wherein the low-E coating (3) differs from the embodiment of Figure 1 in that it further includes a second phase-control layer (3.3.2) disposed on the second electrically conductive layer (3.4.1) and also a third electrically conductive layer (3.4.2) disposed on the second phase-control layer (3.3.2), wherein the sum of the thickness of the second

(3.4.1) and third (3.4.2) electrically conductive layer is smaller than the thickness of the first electrically conductive layer (3.2).

In an embodiment, the second phase-control layer (3.3.2) is selected from the group consisting of: NiCrOx, CrOx, CrOxSi, TiOx, ZrOx, AITiOx, ZrSiOx, ZrTiOx and NbOx. In an embodiment, the third electrically conductive layer (3.4.2) comprises a layer which is: a Ni-based layer, a Cr-based layer, an Inconel-based layer, or a Ti-based layer or a combination thereof.

In an embodiment, the third (3.4.2) electrically conductive layer has a physical thickness comprised in the range between 2 and 20 nm.

Figure 3 depicts a low-E coating (3) according to another embodiment of the invention. In this embodiment of Figure 3, the low-E coating (3) differs from the embodiment of Figure 1 in that it further includes an anti-reflective layer (3.5) deposited on the second electrically conductive layer (3.4.1) for minimizing the interior reflection in the visible part of the spectrum as well as to optimize the reflected color.

In an embodiment, the anti-reflective layer comprises a single layer of SiOx.

In an embodiment, the single layer of SiOx has a physical thickness comprised in a range between 10 and 120 nm, preferably between 30 and 100 nm, and more preferably between 50 and 80 nm.

In an embodiment, the single layer of SiOx has a physical thickness comprised in a range between 90 and 140 nm and preferably between 100 and 115 nm.

Figure 4 depicts a low-E coating (3) according to another embodiment of the invention. In this embodiment of Figure 4, the low-E coating (3) differs from the embodiment of Figure 3 in that it further includes a bottom dielectric barrier layer (3.1) disposed on the first electrically conductive layer (3.2), so that the first electrically conductive layer (3.2) is between the bottom dielectric barrier layer (3.1) and the first phase-control layer (3.3.1).

In an embodiment, the bottom dielectric barrier layer (3.1) comprises a Si-based dielectric layer, preferably based on a compound selected from SiOxNy, SiNx, or a combination of these two compounds. The silicon-based bottom dielectric advantageously acts as a Na diffusion blocking layer. In a particular embodiment, the bottom dielectric barrier layer has a physical thickness comprised in a range between 5 and 70 nm.

Figure 5 depicts a low-E coating (3) according to another embodiment of the invention. In this embodiment of Figure 5, the low-E coating (3) differs from the embodiment of Figure 4 in that the anti-reflective layer is here configured by two different overlapping layers: a first anti-reflective layer (3.5.1) and a second top anti-reflective layer (3.5.2).

In an embodiment, the first anti-reflective layer (3.5.1) is made of NbOx and the second top anti-reflective layer (3.5.2) is made of SiOx. In an embodiment, the first NbOx anti- reflective layer has a physical thickness comprised in a range between 10 and 25 nm and/or and the second SiOx anti-reflective layer has a physical thickness comprised in a range between 10 and 120 nm.

The invention also provides a glazing (1), comprising at least one glass layer and a low- E coating (3) according to the first inventive aspect of the invention. Embodiments of the glazing (1) are shown in Figures 6 to 14. In all depicted embodiment of the glazing (1), the sun represents the exterior side when the glazing (1) is mounted for example in a vehicle, so that the opposite side of the glazing (1) represents the interior part of the vehicle where the occupants are located.

In a possible embodiment, the glazing (1) according to the present invention is monolithic. According to this embodiment, the glazing comprises a single glass layer (2.4) having an outer surface (2.4.1) and an opposed inner surface (2.4.2). Figures 6 and 7 illustrate respective designs of a monolithic glazing comprising a coating deposited on the inner surface (2.4.2) of the single glass layer (2.4), which corresponds to the innermost surface of the single glass layer (2.4) according to a preferred embodiment of the invention. The glazing (1) shown in Figure 6 has a low-E coating (3) according to the embodiment of Figure 1 disposed on at least some portion of the inner surface (2.4.2) of the glass layer (2), e.g., by magnetron sputtering vapor deposition (S). The glazing (1) shown in Figure 7 is also disposed on at least some portion of the innermost surface of the glass layer (2), e.g., by magnetron sputtering vapor deposition (S) and the coating has the layers of embodiment of Figure 2. The term “innermost surface” of the glass layer (2) should be understood as the surface of the glass layer (2) that faces the interior of the vehicle when the glazing is in the operating position. In an alternative embodiment, the glazing according to the present invention is a laminate. According to this embodiment, the glazing comprises at least one first glass layer (2.1) and one second glass layer (2.2) and at least one plastic bonding layer (2.3).

Thus, a laminate glazing (1) according to the present invention comprises:

- at least two glass layers (2.1 , 2.2), namely a first glass layer (2.1) and a second glass layer (2.2), wherein the first glass layer (2.1) has an outer surface (2.1.1) and an inner surface (2.1.2) and the second glass layer (2.2) has an inner surface

(2.2.1) and an outer surface (2.2.2);

- at least one plastic bonding interlayer (2.3) between the first glass layer (2.1) and a second glass layer (2.2); and

- a coating (3) according to any of the embodiments of the first inventive aspect disposed on at least one portion of the inner surface (2.2.1) or the outer surface

(2.2.2) of the second glass layer (2.2), wherein: when the coating (3) is disposed on the outer surface (2.2.2) of the second glass layer (2.2), the first electrically conductive layer (3.2) of the coating (3) is disposed between the outer surface (2.2.2) of the second glass layer (2.2) and the first phase-control layer (3.3.1); or when the coating (3) is disposed on the inner surface (2.2.1) of the second glass layer (2.2), the first phase-control layer (3.3.1) is disposed between the inner surface (2.2.1) of the second glass layer and the first electrically conductive layer (3.2).

Figures 8 to 12 illustrate respective embodiments of the invention of a laminated glazing (1), wherein a low-E coating (3) according to the invention is deposited on the outer surface (2.2.2) of the second glass layer (2.2) of the laminated glazing (1).

Figure 8 shows layers of a laminated glazing (1) according to an embodiment of the invention. In the example of Figure 8, the first glass layer (2.1) has an outer surface (2.1.1), also denoted surface 1 (s1), and an inner surface (2.1.2), also denoted surface

2 (s2), and the second glass layer (2.2) has an inner surface (2.2.1), also denoted surface

3 (s3), oriented towards the inner surface (2.1.2) of the first glass layer (2.1), and an outer surface (2.2.2), also denoted surface 4 (s4), oriented towards the opposite direction. The bonding layer (2.3) is placed on the respective inner surfaces (2.1.2, 2.2.1) of the first glass layer (2.1) and the second glass layer (2.2). The bonding layer (2.3) is laminated together with the two glass layers (2.1 , 2.2) at a temperature between 100 and 150°C.

In the same example of Figure 8, the coating (3) is placed on the outer surface (2.2.2) of the second glass layer (2.2), which corresponds to the innermost surface of the glass laminate, and which is also referred as surface 4 when it is laminated. In particular, a first electrically conductive layer (3.2) is firstly deposited on the outer surface (2.2.2) of the second glass layer (2.2), preferably by magnetron sputtering deposition (S); then a first phase-control layer (3.3.1) is disposed, preferably by magnetron sputtering deposition (S), on the first electrically conductive layer (3.2), that is on the opposite side to the side that is in contact with the second glass layer (2.2). Finally, a second electrically conductive layer (3.4.1) is disposed on said first phase-control layer (3.3.1).

Figure 12 shows layers of a laminated glazing (1) according to an embodiment of the invention. In this example of Figure 12, the coating (3) is also placed on the outer surface (2.2.2) of the second glass layer (2.2). In particular, a bottom dielectric barrier layer (3.1) is firstly deposited on the outer surface (2.2.2) of the second glass layer (2.2), then a first electrically conductive layer (3.2) is deposited on the bottom dielectric barrier layer (3.1), then an ITO layer (3.6) is disposed on the first electrically conductive layer (3.2), then a first phase-control layer (3.3.1) is disposed on ITO layer (3.6), then a second electrically conductive layer (3.4.1) is disposed on said first phase-control layer (3.3.1), and finally a anti-reflective layer (3.5) is disposed on top of the coating stack.

Figure 13 and 14 illustrate two different embodiments of the invention of a laminated glazing (1), wherein a low-E coating (3) according to the invention is deposited on the inner surface (2.2.1) of the second glass layer (2.2).

In the example of Figure 13, a second electrically conductive layer (3.4.1) is firstly deposited on the inner surface (2.2.1) of the second glass layer (2.2), then a first phasecontrol layer (3.3.1) is disposed on the second electrically conductive layer (3.4.1), and finally a first electrically conductive layer (3.2) is disposed on the first phase-control layer (3.3.1). Once the coating (3) is deposited, the first glass layer (2.1) is laminated with the bonding layer (2.3) positioned between the inner surface (2.1.2) of the first glass layer

(2.1) and the first electrically conductive layer (3.2).

In the example of Figure 14, a second electrically conductive layer (3.4.1) is firstly deposited on the inner surface (2.2.1) of the second glass layer (2.2), then a first phasecontrol layer (3.3.1) is disposed on the second electrically conductive layer (3.4.1), then a first electrically conductive layer (3.2) is disposed on the first phase-control layer (3.3.1) and finally a bottom dielectric barrier layer (3.1) is disposed on the first electrically conductive layer (3.2). Additionally, an anti-reflective layer (3.5) can be disposed on the outer surface (2.2.2) of the second glass (2.2) of the laminate. Once the coating (3) is deposited, the first glass layer (2.1) is laminated with the bonding layer (2.3) positioned between the inner surface (2.1.2) of the first glass layer (2.1) and the bottom dielectric barrier layer (3.1).

EXAMPLES

Example 1

The example 1 relates to a laminated glazing according to the invention, embodied as a vehicle roof. A side view of this laminated glazing is depicted in Figure 9.

The layer sequence of the glazing (1) is as follows: a first glass layer (2.1) with a thickness of 2.1 mm, a bonding layer (2.3) of PVB with a thickness of 0.76 mm, a second glass layer (2.2) with a thickness of 1.6 mm, a bottom dielectric barrier layer (3.1) of SiNx with a thickness of 56 nm, a first electrically conductive layer (3.2) of NiCr with a thickness of 28 nm, a first phase-control layer (3.3.1) of NbOx with a thickness of 35 nm, a second electrically conductive layer (3.4.1) of NiCr with a thickness of 4 nm, a first anti-reflective layer (3.5.1) of NbOx (3.5.1) with a thickness of 13 nm, and a second anti-reflective layer (3.5.2) of SiOx with a thickness of 73 nm.

The transmission (T) and reflection (R) spectra of this laminate are as depicted in Figure

15. The letter “T” refers to the light transmission spectra, and the letter “R” refers to the light reflection spectra.

The measured exterior visible reflection T(0°) is 5.21 % and R(8°) is 4.55%; wherein T and R are measurements in transmission and reflection in the angles of measurements of 0 and 8 degrees, respectively.

Emissivity is 0.2.

Cl ELAB color coordinates are: a*(T(O⁰)) = 0.36; b*(T(O⁰)) = -0.29 a*(R(8⁰)) = 0.34; b*(R(8⁰)) = -0.24

The thickness ratio between the first and second electrically conductive layers (3.2, 3.4.1) is 7.0.

The refractive index of the first phase-control layer (3.3.1) is about 2.3 at a wavelength reference of 550 nm.

Example 2

The example 2 also relates to a laminated glazing according to the invention, embodied as a vehicle roof. A side view of this laminated glazing is depicted in Figure 10.

The layer sequence of the glazing (1) is as follows: a first glass layer (2.1) with a thickness of 2.1 mm, a bonding layer (2.3) of PVB with a thickness of 0.76 mm, a second glass layer (2.2) with a thickness of 1.6 mm, a bottom dielectric barrier layer (3.1) of SiOxNy with a thicknesses of above 50 nm, a first electrically conductive layer (3.2) of NiCr with a thickness of < 24 nm, a first phase-control layer (3.3.1) with a thickness of above 30 nm, a second electrically conductive layer (3.4.1) of NiCr with a thickness of ~4 nm, and an optional anti-reflective layer (3.5) with a thickness of above 50 nm.

The thickness ratio between the two functional electrically conductive layers (3.2, 3.4.1) is 6.

The refractive index of the first phase-control layer (3.3.1) is about 2.3 at a wavelength reference of 550 nm.

Example 3

The example 3 also relates to a laminated glazing according to the invention, embodied as a vehicle roof. A side view of this laminated glazing is depicted in Figure 11.

The layer sequence of the glazing (1) is as follows: a first glass layer (2.1) with a thickness of 2.1 mm, a bonding layer (2.3) of PVB with a thickness of 0.76 mm, a second glass layer (2.2) with a thickness of 1.6 mm, a bottom dielectric barrier layer (3.1) of SiNx with a thickness of 56 nm, a first electrically conductive layer (3.2) of NiCr with a thickness of 28 nm, a first phase-control layer (3.3.1) of NbOx with a thickness of 35 nm, a second electrically conductive layer (3.4.1) of NiCr with a thickness of 4 nm, a second phase-control layer (3.3.2) of NbOx with a thickness of 13 nm, a third electrically conductive layer (3.4.2) of NiCr with a thickness of 1 nm, a first anti-reflection layer (3.5.1) of NbOx with a thickness of 5 nm, and a second anti-reflection layer (3.5.1) of SiOx with a thickness of 73 nm.

The transmission (T) and reflection (R) spectra of this laminate are as depicted in Figure 16.

The measured exterior visible reflection T(0°) is 4.4% and R(8°) is 2.49%; wherein T and R are measurements in transmission and reflection in the angles of measurements of 0 and 8 degrees, respectively.

Cl ELAB color coordinates are: a*(T(O⁰)) = 0.39; b*(T(0°)) = -1.16 a*(R(8⁰)) = -0.28; b*(R(8⁰)) = 0.49

The thickness ratio between the two functional electrically conductive layer (3.2, 3.4.1) is 5.91.

The refractive index of the first phase-control layer (3.3.1) is above 2.0 at a wavelength reference of 550 nm.

Example 4

The example 4 also relates to a laminated glazing according to the invention, embodied as a vehicle roof. A side view of this laminated glazing is depicted in Figure 14.

The layer sequence of the glazing (1) is as follows: a first glass layer (2.1) with a thickness of 2.1 mm a bonding layer (2.3) of PVB with a thickness of 0.76 mm, a bottom dielectric barrier layer (3.1) of SiOxNx with a thickness of 29 nm, a first electrically conductive layer (3.2) of NiCr with a thickness of ~29nm, a first phase-control layer (3.3.1) with a thickness of 58 nm, a second electrically conductive layer (3.4.1) of NiCr with a thickness of ~4 nm, and a second glass layer (2.2) with a thickness of 1.6 mm, an optional anti-reflective layer (3.5) of SiOx with a thickness of 76 nm.

The thickness ratio between the two functional electrically conductive layers (3.2, 3.4.1) is 7.25.

The refractive index of the first phase-control layer (3.3.1) is about 2.3 at a wavelength reference of 550 nm.

As can be seen in all 4 examples, the second electrically conductive layer (3.4.1) has a physical thickness much less than the physical thickness of the first electrically conductive layer (3.2).

The coating (3) of the present invention operates in such a way that, once it is deposited on a glass layer (2), a light wave (IL) coming from the interior part of the vehicle in an automotive application (see Figure 9) impacts the coating (3), the light wave firstly impacts the top layer, which in the example of Figure 9 corresponds to the second anti- reflective layer (3.5.2). The light wave goes through the coating layers and reaches the second electrically conductive layer (3.4.1). A part of the light wave (R2) is reflected backwards from the second electrically conductive layer (3.4.1) and another part of the light wave goes through the second electrically conductive layer (3.4.1) and also through the first phase-control layer (3.3.1) until it impacts the first electrically conductive layer (3.2). A part of the light wave impacting the first electrically conductive layer (3.2) is reflected (R1) backwards and when it passes through the first phase-control layer (3.3.1) its phase is shifted 180°. Therefore, the reflected light wave (R1) and (R2) are 180° shifted and are cancelled due to destructive optical interference. Said destructive optical interference helps to counteract high metal or alloy reflectivity of the first electrically conductive layer, and therefore, permits to control the emissivity.

Claims

1. A coating (3), comprising: a first electrically conductive layer (3.2); a first phase-control layer (3.3.1); and a second electrically conductive layer (3.4.1); wherein the first phase-control layer (3.3.1) is disposed between the first (3.2) and the second (3.4.1) electrically conductive layer; wherein the first electrically conductive layer (3.2): is a metal or metal alloy; and has a physical thickness of less than or equal to 100 nm, preferably less than or equal to 40 nm; wherein the first phase-control layer (3.3.1): has an optical thickness that shifts % wavelength the phase of a light wave passing through the first phase-control layer; and has a refractive index of at least 2.0 at a wavelength reference of 550 nm; wherein the second electrically conductive layer (3.4.1) has a physical thickness less than the physical thickness of the first electrically conductive layer (3.2); and wherein the coating (3) has a sheet resistance less than 100 Q/sq, preferably less than or equal to 40 Q/sq.

2. The coating (3) according to the preceding claim, further comprising: a second phase-control layer (3.3.2) disposed on the second electrically conductive layer (3.4.1).

3. The coating (3) according to claim 2, further comprising: a third electrically conductive layer (3.4.2) disposed on the second phase-control layer (3.3.2), wherein the sum of the thicknesses of the second (3.4.1) and third (3.4.2) electrically conductive layer is smaller than the thickness of the first electrically conductive layer (3.2).

4. The coating (3) according to any one of the preceding claims, wherein at least one of the first (3.3.1) and second (3.3.2) phase-control layer is selected from the group consisting of: NiCrOx, CrOx, CrOxSi, TiOx, ZrOx, AITiOx, ZrSiOx, ZrTiOx and NbOx.

5. The coating (3) according to any one of the preceding claims, wherein at least one of the first (3.2), second (3.4.1) and third (3.4.2) electrically conductive layer comprises a layer which is: a Ni-based layer, a Cr-based layer, an Inconel-based layer, or a Ti- based layer or a combination thereof.

6. The coating (3) according to any one of the preceding claims, wherein the first electrically conductive layer (3.2) has a physical thickness comprised in the range between 20 and 100 nm, preferably in the range between 20 and 40 nm.

7. The coating (3) according to any one of the preceding claims, wherein the second (3.4.1) and/or the third (3.4.2) electrically conductive layer has a physical thickness comprised in the range between 2 and 20 nm.

8. The coating (3) according to any one of the preceding claims, wherein the first phase-control layer (3.3.1) has a physical thickness comprised in the range between 20 and 120 nm.

9. The coating (3) according to any one of the preceding claims, having a sheet resistance less than 50 Q/sq, preferably less than or equal to 40 Q/sq, and, more preferably, less than 20 Q/sq.

10. The coating (3) according to any one of the preceding claims, further comprising a bottom dielectric barrier layer (3.1) disposed on the first electrically conductive layer (3.2), so that the first electrically conductive layer (3.2) is between the bottom dielectric barrier layer (3.1) and the first phase-control layer (3.3.1) , wherein the bottom dielectric barrier layer (3.1) preferably comprises a Si-based dielectric layer, preferably based on a compound selected from SiOxNy, SiNx, or a combination of these two compounds.

11. The coating (3) according to any one of the preceding claims, further comprising at least one anti-reflective layer (3.5) disposed on the second electrically conductive layer (3.4.1) or on the third electrically conductive layer (3.4.2).

12. The coating (3) according to any one of the preceding claims, further comprising an ITO layer (3.6) disposed between the first electrically conductive layer (3.2) and the first phase-control layer (3.3.1), wherein the ITO layer (3.6) has a physical thickness comprised in the range between 40 and 80 nm.

13. A glazing (1), comprising: at least one glass layer having an outer surface (2.4.1 , 2.1.1 , 2.2.2) and an inner surface (2.4.2, 2.1.2, 2.2.1), and a coating (3) according to any one of the preceding claims disposed on at least one portion of the inner (2.4.2, 2.2.1) or outer (2.2.2) surface of the at least one glass layer, wherein: the first electrically conductive layer (3.2) is disposed between the inner

(2.4.2) or outer (2.2.2) surface of the at least one glass layer and the first phase-control layer (3.3.1); or the first phase-control layer (3.3.1) is disposed between the inner surface (2.2.1) of the least one glass layer and the first electrically conductive layer

(3.2).

14. A method for manufacturing a glazing (1) as claimed in claim 13, comprising the following steps: providing at least one glass layer having an outer surface (2.1.1 , 2.2.2) and an inner surface (2.1.2, 2.2.1), wherein the outer surface (2.1.1 , 2.2.2) is opposite to the inner surface (2.1.2, 2.2.1); providing a coating (3), wherein providing a coating (3) comprises: depositing a first electrically conductive layer (3.2) on at least a portion of the outer surface (2.2.2) of the at least one glass layer or on at least one portion of the inner surface (2.1.2, 2.2.1) of the at least one glass layer, wherein the first electrically conductive layer (3.2): is a metal or metal alloy, and has a physical thickness of less than or equal to 100 nm, preferably less than or equal to 40 nm; depositing a first phase-control layer (3.3.1) on at least a portion of said first electrically conductive layer (3.2), wherein the first phase-control layer (3.3.1): has an optical thickness that shifts % wavelength the phase of a light wave passing through the first phase-control layer, and has a refractive index of at least 2.0 at a wavelength reference of 550 nm; depositing a second electrically conductive layer (3.4.1) on said first phasecontrol layer (3.3.1), wherein the second electrically conductive layer (3.4.1): has a physical thickness less than the physical thickness of the first electrically conductive layer (3.2); wherein the sheet resistance of the coating (3) is less than 100 Q/sq, preferably less than or equal to 40 Q/sq.

15. The method according to claim 14, further comprising an additional step of depositing at least one anti-reflective layer (3.5) on at least a portion of the second electrically conductive layer (3.4.1).

16. The method according to any one of claims 14 or 15, wherein: the at least one glass layer provided is a fully bent glass layer (2a) and the first electrically conductive layer (3.2) is deposited on said fully bent glass layer (2a); and the method optionally comprises a step of laminating the result of the method of claim 14 or 15 to a laminated glass pane.

17. The method according to any one of claims 14 or 15, wherein: the at least one glass layer provided is a partially bent glass layer (2b) or at least one flat glass layer (2c); the first electrically conductive layer (3.2) is deposited on said partially bent glass layer (2b) or on said flat glass layer (2c); the method optionally comprises a step of performing a second bending step onto the result of the method of claim 14 or 15 to obtain a final curved shape; and the method optionally comprises a step of laminating the result of the method of claim 14 or 15 to a laminated glass pane.