EP4429885A1

EP4429885A1 - A solar control glass article with variable optical properties

Info

Publication number: EP4429885A1
Application number: EP22889590.0A
Authority: EP
Inventors: Uditendu MUKHOPADHYAY; Soumyadeep MISRA; Priyesh DHANDHARIA
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2021-11-08
Filing date: 2022-11-04
Publication date: 2024-09-18
Also published as: MX2024005571A; CO2024007157A2; EP4429885A4; WO2023079577A9; WO2023079577A1

Abstract

A material comprising a transparent substrate deposited with a stack of thin layers on at least one of its surface to act on the solar and/or infrared radiation likely to strike said surface is disclosed. The stack of thin layers successively comprises, starting from the substrate not more than two functional layers F1, F2 based on NiCr/ NiCrN or Nb/ NbN and three dielectric coatings M1, M2, M3 comprising at least one dielectric layer such that each of the metallic functional layer is sandwiched between two dielectric coatings. The proposed material has significant influence on the optical properties of the resultant solar control glass article such that variation in the position of the functional layer material F1, F2 brings about a variation in the optical properties to cater to the varied application areas.

Description

A SOLAR CONTROL GLASS ARTICLE WITH VARIABLE OPTICAL PROPERTIES

Technical Field

The present disclosure relates, in general to a material comprising a transparent substrate, on the surface of which a stack of thin layers is deposited which comprises n functional layers and n+1 dielectric layers making it possible to act on the solar and/or infrared radiation likely to strike said surface. More specifically the invention relates to a material having significant influence on the optical properties such that variation in the position of the functional layers brings about a variation in the optical properties of the material.

Background

Solar control glass has a large part to play in the future of construction, as external temperatures will continue to rise and so will the expectations of comfort. Legal agreements and devices aimed at reducing the environmental impacts of human activities are increasing on regional, national and international scales. These agreements and arrangements aim in particular to reduce the energy consumption of infrastructure. They recommend or oblige in particular the equipment of buildings and transport vehicles so as to reduce the energy consumption of their air conditioning and heating means. Energy consumption resulting in increased CO2 emission is already a grave threat to the environment.

The key performance parameters for any energy efficient fenestration product are the Solar Heat Gain Coefficient (SHGC), the heat transfer coefficient (U-value) and the visible light transmission (Tvis). The U-value is a measure of the insulating value of a window; the lower the value, the better the insulation. SHGC is the ratio of the solar heat gain through the window system relative to the incident solar radiation and Tvis is weighted for human eye sensitivity. Reflected color and haze are equally important aesthetic properties. Yet another fundamental function of architectural windows is to supply visual connection between the inside and outside of buildings.

In solar control coatings, the highly absorptive metal film that would otherwise be opaque to the visible light is sandwiched between the two dielectric layers that act as antireflective coatings. Three-layer systems of Di el ectric/Metal/Di electric on glass substrates have been used for spectrally selective coatings for various purposes including the energy efficiency. By varying the material and thickness of the three layers, the optical properties of the layer films can be tailored to suit different applications. Also known are solar control coatings with five-layer systems comprising two absorptive metal layers i.e., Dielectric/Metal/Dielectric/Metal/Dielectric.

While such three-layer systems and five-layer systems are widely known in the art, what is not known is making a solar control article having variable optical properties, one in which the means for varying the optical properties have been studied. The choice of material for the absorptive metal films play a significant role in influencing the properties of the solar control article (viz., internal and external reflection values) and further the positioning of such a chosen material for the reflective metal films influences the overall optics of the solar control article. While the former is widely known and studied, the latter is not.

A wide variety of coating materials have been proposed for glazing panels, and for several different desired properties of the glazing. U.S. patent 8,286,395 granted to the Applicant of the present invention teaches a stack comprising two functional absorptive layers, each one flanked by two transparent layers containing a dielectric material for controlling solar radiation. Metals belonging to niobium, tantalum, molybdenite, or zirconium group are described for glazing intended for thermal insulation and/or solar protection. The internal and external aesthetic of a glass article coated with the said stack is significantly managed. Referring to U.S. granted patent 8,703,281, teaches solar control coating having an infrared (IR) reflecting layer and a breaker layer including a material such as NiCr, NiCrN_x, NbCr, NbCrNx, NbZr, NbZrNx, Nb and/or NbNx, each sandwiched between a pair of dielectric layers.

Referring to couple of other prior art references, PCT publications 2017/160324; 2017/160325; 2017/160326 and 2017/160327, all teach coated articles including two or more infrared (IR) reflecting layers (e.g., of or including NbZr, Nb, NiCr, NiCrMo, and/or a nitride thereof) sandwiched between at least dielectric layers and the coatings are so designed to realize varied glass side reflective colorations in combination with a low solar factor (SF) and/or a low solar heat gain coefficient (SHGC).

As mentioned earlier, the glazed surfaces have a significant aesthetic function for buildings and transport vehicles in which they are likely to be incorporated. In certain applications, the coated article must achieve, in external reflection, a colored surface appearance. The shades of color should ideally vary little depending on the angle of observation.

Most of the known coating system in the prior art either achieve a lower internal reflection or a lower external reflection, often at the cost of increasing the other. For example, the referenced prior art U.S. patent 8,286,395 and U.S. patent 8,703,281 teach a thick dielectric layer positioned between the two absorbing/functional layers and realize a lower external reflection compared to internal reflection. While most of the cited reference describe the influence of layer materials on reflection, none describe the influence of the position of different layer materials from the surface of the glass substrate bearing them and their resultant impact on reflection, viz., internal and external reflection values and ratio of internal: external reflection value.

The inventors of the present disclosure have extensively studied the combination of two functional layers: NiCr/NiCrN and Nb/NbN to determine their positional influence on the optical performance of the glass article coated therewith. The present disclosure further determines the combination of two functional layers NiCr/NiCrN and Nb/NbN to provide significant differential optical performance as that compared to double functional layers bearing either two layers of NiCr/NiCrN or two layers of Nb/NbN.

Hence the objective of the present disclosure is therefore to study the stack configuration Glass|Dielectric(Ml)|FLl |Dielectric(M2)|FL2|Dielectric(M3) to determine the optical characteristics obtained when FL1 is deposited with NiCr or NiCrNx and FL2 is deposited with Nb or NbN_x and vice versa. According to the disclosure, by introducing different functional layers, asymmetry in the reflection level can be achieved. This asymmetry can be calculated as the ratio between internal reflection (RC) and external reflection (RG) i.e., RC/RG and RG/RC. It is therefore sought to enhance aesthetics while keeping a constant light transmission suitable for allowing good insulation and good vision.

The Applicant has surprisingly discovered that when FL1 is deposited with NiCr or NiCrNx and FL2 is deposited with Nb or NbN_x, the internal reflection of such a coated glass article is much lower compared to a coated glass article comprising FL1 deposited with Nb or NbNx and FL2 deposited with NiCr or NiCrNx. Likewise, a coated glass article comprising FL1 deposited with NiCr or NiCrNx and FL2 is deposited with Nb or NbNx, has a higher external reflection when compared to a coated glass article comprising FL1 deposited with Nb or NbN_x and FL2 deposited with NiCr or NiCrNx. Thus the findings of the present disclosure present an excellent opportunity to obtain variable optical characteristics for the materials deposited in FL1 and FL2.

Unfortunately, none of the referenced prior art describe the positional influence of the materials of the functional layers and study the variable optical characteristics and aesthetic characteristics according to the present disclosure. In view of the above, it will be appreciated that there exists a need in the art to develop such coated article that can cater to a diverse range of desired optical characteristics while also retaining the desired aesthetics, solar control properties, insulation and visual comfort It is thus a purpose of this disclosure to help achieve all the said characteristics, detail of which will become apparent to the skilled artisan once given the following disclosure.

Certain example embodiments of this disclosure relate to a solar control glass article having an internal reflection (RC) of less than 15% and a ratio of said internal reflection (RC) to external reflection (RG) not exceeding 1.2. Certain other example embodiments of the disclosure relate to a solar control glass article having an external reflection (RG) of less than 30% and a ratio of said external reflection (RG) to internal reflection (RC) not exceeding 2. Certain example embodiments of this invention also relate to a heat treatable solar control glass article and certain others to a solar control glass article that is not heat treatable.

Summary of the Disclosure

In one aspect of the present disclosure, a solar control glass article comprising a transparent substrate deposited with a stack of thin layers on at least one of its surface comprising, n functional layers and n+ 1 dielectric layers, wherein n=2 such that each functional layer is sandwiched between 2 dielectric layers and optionally an overcoat layer, wherein the overcoat layer forms the outermost layer of the thin multilayer coating is disclosed. The solar control glass article characterized in that when the first functional layer (Fl) is made of NiCr or NiCrN having a thickness range of 0.1 nm to 30 nm; and the second functional layer (F2) is made of Nb or NbN having a thickness range of 2 nm to 35 nm, internal reflection (RC) of the solar control glass article is less than 15% and a ratio of said internal reflection (RC) to external reflection (RG) does not exceed 1.2. The solar control glass article characterized in that when the first functional layer (Fl) is made of Nb or NbN having a thickness range of 0.1 nm to 30 nm; and the second functional layer (F2) is made of NiCr or NiCrN having a thickness range of 0.1 nm to 35 nm, the external reflection (RG) of the solar control glass article is less than 30% and a ratio of said external reflection (RG) to internal reflection (RC) does not exceed 2.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawings

Embodiments are illustrated by way of example and are not limited to those shown in the accompanying figures.

FIG. 1 illustrates a stack of thin layers deposited on a transparent glass substrate, according to one embodiment of the present disclosure; FIG. 2 illustrates a stack of thin layers deposited on a transparent glass substrate, according to one other embodiment of the present disclosure;

FIG. 3 illustrates a stack of thin layer deposited on a transparent glass substrate according to the first major embodiment of the present disclosure;

FIG. 4 illustrates a stack of thin layer deposited on a transparent glass substrate according to the second major embodiment of the present disclosure;

FIG. 5 illustrates a plot between the internal reflection (RC) and external reflection (RG) for varying thickness ranges of Ml for samples 6 and 7;

FIG. 6 illustrates a plot between the internal reflection (RC) and external reflection (RG) for varying thickness ranges of M2 for samples 6 and 7;

FIG. 7 illustrates a plot between the internal reflection (RC) and external reflection (RG) for varying thickness ranges of M3 for samples 6 and 7;

FIG. 8 illustrates a plot between the internal reflection (RC) and external reflection (RG) for varying thickness of the functional materials NiCrN for samples 6 and 7;

FIG. 9 illustrates a color variation of a*G and b*G for varying thicknesses of NiCrN for samples 6 and 7;

FIG. 10 illustrates a plot between the internal reflection (RC) and external reflection (RG) for varying thickness of the functional materials NbN for samples 6 and 7; and

FIG. 11 illustrates a color variation of a*G and b*G for varying thicknesses of NbN for samples 6 and 7.

Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention.

Detailed Description

Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts. Embodiments disclosed herein are related to material having a better thermal performance and desired aesthetics.

FIG. 1 illustrates a structure of a stack of thin layer having two functional layers Fl, F2 deposited on a transparent substrate 10. Each of the functional layers 50, 100 is positioned between dielectric coatings 20 (Ml), 40 (M2), 80 (M3) such that: the first functional layer 50, starting from the substrate, is positioned between the dielectric coatings 20, 40 and the second functional layer 100 is positioned between the dielectric coatings 40, 80. The dielectric coatings 20, 40 and 80 each comprise at least one dielectric layer.

The stack of thin layers may further comprise barrier layers 49, 99 (not represented) deposited as under layers in contact with the functional layer and/or barrier layers 59, 109 (not represented) deposited as over layers in contact with the functional layer (not represented). The stack of thin layers may further optionally comprise at least one overcoat layer 1000 (not represented) in contact with the dielectric coating 80 (M3). In such an embodiment the barrier layer 109 is in contact with the said overcoat layer 1000.

By adjusting the position of the functional layers Fl, F2 the optical properties of the transparent substrate bearing the stack of thin layers can be significantly influenced. The major advantage of the invention is that it provides a solar control glass article whose visible transmission, internal and external reflection values and internal and external reflection color are tunable as desired. It is well known that the choice of material for the functional layers Fl, F2 significantly impacts the optical properties of a product but what is not known is the position of such chosen functional layer materials (from the surface of the glass substrate) significantly impacting the optical properties and hence an understanding of this positional relationship of the functional layer material opens up numerous opportunities to fine tune the optical properties of the product as desired.

Furthermore, the inventors have surprisingly found that the stack of thin layers proposed in the present invention (having different materials for Fl and F2) provide significantly improved solar control performance when compared to prior known stack of thin layers comprising identical materials for Fl and F2.

Within the meaning of the present invention, the label “first”, “second” for the functional layers and “first”, “second”, “third” for the dielectric coatings are defined starting from the substrate bearing the stack and with reference to the layers or coatings having the same function. For example, the functional layer closest to the substrate is the first functional layer, the one farthest from the substrate is the second functional layer. Likewise, the dielectric coating closest to the substrate is the first dielectric coating, the next one moving away from the substrate is the second dielectric coating etc. Thicknesses stated in the present document with no other specifications are physical, real or geometric thicknesses and are expressed in nanometers (and not optical thicknesses).

The inventors of the present invention have worked with two absorbing functional layer materials for Fl and F2: Nb or NbN and NiCr or NiCrN. Thus the thin multilayer coating proposed by the present invention comprises in a first major embodiment: Glass | Dielectric Coating (Ml) | Nb or NbN (Fl) | Dielectric coating (M2) | NiCr or NiCrN (F2) | Dielectric coating (M3); and

In a second major embodiment of the present invention, the thin multilayer coating comprises of:

Teachings of the present invention in the following sections will establish how different materials in Fl and F2 can provide significantly different optical performance when compared to having the same materials in Fl and F2. Furthermore, the inventors have also studied the inter-relationship between: the position of the functional layer materials; thickness of Fl and F2 and thickness of dielectric coatings Ml, M2 and M3. The following disclosures and examples will demonstrate how the above stated factors influence the internal reflection (RC), external reflection (RG) and light transmission (TL).

According to a first major embodiment of the present invention, thickness Tl of Fl comprising materials NiCr or NiCrN preferably ranges between 0.1 nm to 30 nm and thickness T2 of F2 comprising materials Nb or NbN preferably ranges between 2 nm to 35 nm. Likewise, according to a second major embodiment, the thickness Tl of Fl comprising the materials Nb or NbN preferably ranges between 0.1 nm to 30 nm and thickness T2 of F2 comprising materials NiCr or NiCrN preferably ranges between 0.1 nm to 35 nm. These thickness ranges for Fl and F2 are best suited for obtaining internal reflection (RC) of less than 15% where Fl is made of NiCr or NiCrN and F2 is made of Nb or NbN and an external reflection (RG) of less than 30% where Fl is made of Nb or NbN and F2 is made of NiCr or NiCrN.

According to multiple embodiments of the present invention, thickness of dielectric coating 20 (Ml) preferably ranges between 1 nm and 100 nm; thickness of dielectric coating 40 (M2) preferably is less than or equal to 65 nm; and thickness of dielectric coating 80 (M3) preferably ranges between 20 nm and 60 nm, inclusive of all said values mentioned for Ml, M2 and M3. The three dielectric coatings 20, 40, 80 comprise at least one dielectric layer based on a material selected from silicon nitride, titanium nitride, aluminum nitride, oxynitrides of silicon and aluminum, silicon aluminium nitride, zinc oxide, tin and zinc oxide, tin oxide, titanium oxide, silicon oxide, aluminum oxide or titanium and tin oxide, alone or in combination. According to a preferred embodiment of the present invention, the dielectric coatings 20, 40, 80 is made of silicon nitride. According to a most preferred embodiment of the present invention, the dielectric coatings 20, 40, 80 is made of silicon nitride doped with aluminum.

According to another embodiment, the dielectric coatings 20, 40, 80 satisfy the conditions: the total thickness of the dielectric layers 20, 40, 80 (M1+M2+M3) is less than or equal to 150 nm. According to few embodiments of the present invention, the thickness ratio of the first dielectric layer/third dielectric layer (M1/M3) is less than or equal to 2. According to certain other embodiments of the present invention, the thickness ratio of the first dielectric layer/third dielectric layer (M1/M3) is less than or equal to 4. Further, according to few exemplary embodiments of the present invention, the dielectric coating 40 (M2) may be absent. According to yet another alternative embodiment of the present invention, the dielectric coating 80 (M3) farthest from the glass substrate is made of metal oxide selected from the group consisting of TiO_x, TiZrO_x, NbO_x or SiO_x.

According to yet another embodiment of the present invention, the stack of thin layers may further comprise barrier layers 49, 99 deposited as under layers in contact with the functional layer Fl and/or F2; barrier layers 59, 109 deposited as over layers in contact with the functional layer Fl and/or F2, as illustrated in FIG. 2. In alternative embodiments, the barrier layers 49, 99 or 59, 109 may be present such as to sandwich only one of the two functional layers Fl, F2. The role of the barrier layers deposited over and below the functional layers Fl, F2 is conventionally to improve chemical durability or minimize tempering shift.

The barrier layers are made of either titanium or niobium or silicon aluminium or absorbing silicon nitride. When these barrier layers are deposited in metallic form, these layers may undergo a partial or complete oxidation depending on their thickness and the nature of the layers that surround them, for example, at the time of the deposition of the next layer or by oxidation in contact with the underlying layer. According to multiple embodiments of the present invention, the thickness of the barrier layers 49, 99, 59, 109, if present preferably ranges between 0.1 nm and 5 nm.

According to an optional embodiment, the stack of thin layers may further comprise at least one overcoat layer 1000 in contact with the dielectric coating 80 (M3), as illustrated in FIG. 2. The overcoat layer 1000 comprises titanium zirconium nitride or oxynitride, zirconium oxide or titanium oxide or their combinations thereof. According to a preferred optional embodiment, the overcoat layer 1000 comprises titanium zirconium oxide.

Typically, the configuration of the stack of thin layers is designed such that the external reflection (RG) is higher and the internal reflection (RC) is lower. This is because the high external reflection (RG) provides privacy during the day time and the low internal reflection (RC) provides a clear view of the external environment. Alternatively, in certain other applications high external reflection provides a mirror-like effect but the depth of required external aesthetic cannot be achieved. To achieve such aesthetics, low external reflection is required. Such a change in desired optical characteristics can be brought about by the positional change of materials in Fl and F2 as will be taught by the present invention.

According to a first major embodiment of the present invention, a solar control glass constructed having the below configuration of the stack of thin layers:

Glass | Dielectric Coating (Ml) | NiCr or NiCrN (Fl) | Dielectric coating (M2) | Nb or NbN (F2) | Dielectric coating (M3), exhibits the following optical characteristics: internal reflection (RC) less than external reflection (RG); internal reflection (RC) less than 15%; ratio of internal reflection (RC) to external reflection (RG) not exceeding 1.2; external reflection (RG) values of a*G ranging between -15 to +5 and b*G ranging between -20 to +20; and

- visible light transmission (TL) ranging between 5% and 60%.

According to a second major embodiment of the present invention, a solar control glass constructed having the below configuration of the stack of thin layers:

Glass | Dielectric Coating (Ml) | Nb or NbN (Fl) | Dielectric coating (M2) | NiCr or NiCrN (F2) | Dielectric coating (M3), exhibits the following optical characteristics: external reflection (RG) less than internal reflection (RC) external reflection (RG) of less than 30%; ratio of external reflection (RG) to internal reflection (RC) not exceeding 2 external reflection (RG) values of a*G ranging between -15 to +15 and b*G ranging between -30 to +30; and

- visible light transmission (TL) ranging between 5% and 60%.

It was surprisingly found that although the positional changes in the functional layers Fl, F2 significantly changed the internal and external optics, the visible light transmission (TL) remained unaffected.

The transparent substrates according to the present invention are preferably made of an inorganic rigid material, such as glass, or an organic material based on polymers (or made of polymer). The substrate is preferably a sheet of glass or of glass-ceramic. The substrate is preferably transparent, colorless (it is then a clear or extra-clear glass) or colored, for example colored blue, grey, green or bronze. The glass is preferably of soda-lime-silica type, but it may also be made of glass of borosilicate or alumino-borosilicate type. The substrate advantageously has at least one dimension greater than or equal to 1 m, or even 2 m and even 3 m. The thickness of the substrate generally varies between 0.5 mm and 19 mm, preferably between 0.7 and 9 mm, in particular between 2 and 12 mm, or even between 4 and 10 mm. The substrate may be flat or curved, or even flexible.

The material, that is to say the substrate coated with the stack, may undergo a high-temperature heat treatment such as an annealing, for example a flash annealing such as a laser or flame annealing and/or a tempering. The temperature of the heat treatment is greater than 500° C, preferably greater than 550° C, and better still greater than 600° C. The substrate coated with the stack may therefore be tempered. The heat treated solar control glass article has a superior color matchability with a ΔE* of less than 4.0 for external reflection and transmission, according to a preferred embodiment.

The invention also relates to a glazing comprising a material according to the invention. Conventionally, the faces of a glazing are denoted starting from the outside of the building and by numbering the faces of the substrates from the outside towards the inside of the passenger compartment or room that it equips. This means that the incident solar light passes through the faces in the increasing order of their number.

The stack is preferably positioned in the glazing so that the incident light coming from outside passes through the first dielectric coating before passing through the first functional layer Fl. The stack is not deposited on the face of the substrate that defines the external wall of the glazing but on the inner face of this substrate. The stack is therefore advantageously positioned on face 2, face 1 of the glazing being the outermost face of the glazing, as is customary.

The material may be intended for applications that require the substrate coated with the stack to have undergone a heat treatment at a high temperature such as a tempering or an annealing. The glazing of the invention may be in the form of monolithic, laminated or multiple glazing, in particular double glazing or triple glazing.

In the case of a monolithic glazing, the stack is preferably deposited on face 2, that is to say that it is on the substrate that defines the external wall of the glazing and more specifically on the inner face of this substrate. A monolithic glazing comprises 2 faces; face 1 is on the outside of the building and therefore constitutes the external wall of the glazing, face 2 is on the inside of the building and therefore constitutes the internal wall of the glazing.

A multiple glazing comprises at least two substrates kept at a distance so as to delimit a cavity filled by an insulating gas (e.g., dry air, Ar, Kr or their mixture). The materials according to the invention are very particularly suitable when they are used in double glazing with enhanced thermal insulation (ETI). A double glazing comprises 4 faces; face 1 is outside of the building and therefore constitutes the external wall of the glazing, face 4 is inside the building and therefore constitutes the internal wall of the glazing, faces 2 and 3 being on the inside of the double glazing. The stack may be on face 2, 3 or 4 of the glazing.

In the same way, a triple glazing comprises 6 faces; face 1 is outside of the building (external wall of the glazing), face 6 is inside the building (internal wall of the glazing) and faces 2 to 5 are on the inside of the triple glazing. A laminated glazing comprises at least one structure of first substrate/sheet(s)/second substrate type. The stack of thin layers is positioned on at least one of the faces of one of the substrates. The stack may be on the face of the second substrate not in contact with the, preferably polymer, sheet. This embodiment is advantageous when the laminated glazing is assembled as double glazing with a third substrate.

According to a first major embodiment of the present invention, the monolithic glazing according to the invention comprising NiCr or NiCrN in Fl and Nb or NbN in F2, has external reflection values of a*G ranging between -15 to +15 and b*G ranging between -20 to +20. This along with a low internal reflection (RC) value of less than 15% aid in visual comfort for people facing the interior. Likewise, the glazing has internal reflection values of a*C ranging between -15 to +30 and b*C ranging between -30 to +30. Furthermore, these visual appearance remains virtually unchanged irrespective of the angle of incidence with which the glazing is observed (normal incidence and under an angle). This means that an observer does not have the impression of a significant lack of uniformity in color or in appearance.

According to a second embodiment of the present invention, the monolithic glazing according to the invention comprising Nb or NbN in Fl and NiCr or NiCrN in F2, has internal reflection values of a*C ranging between -25 to +25 and b*C ranging between -50 to +50. This along with an external reflection (RG) of less than 30% aid in privacy for people facing the interior of the building. Likewise, the glazing has external reflection values of a*G ranging between -15 to +15 and b*G ranging between -30 to +30. This along with in internal reflection (RC) value less than equal to 50% aid in visual comfort for people interior of the gl3zing. Furthermore, these visual appearance remains virtually unchanged irrespective of the angle of incidence with which the glazing is observed (normal incidence and under an angle). This means that an observer does not have the impression of a significant lack of uniformity in color or in appearance.

The glazing of the invention has colors in transmission in the L*a*b* color measurement system: a*T between -7 to +7, preferably between -6 to +5; and b*T between -20 to +20, preferably between -12 to +15, when NiCr or NiCrN is present in Fl and Nb or NbN is present in F2.

The glazing of the invention has colors in transmission in the L*a*b* color measurement system: a*T between -10 to +10, preferably between -7 to +8; and b*T between -20 to +20, preferably between -15 to +18, when Nb or NbN is present in Fl and NiCr or NiCrN is present in F2.

According to advantageous embodiments, the glazing of the invention has, in particular, according to the first and second major embodiments the following performances: a solar factor less than or equal to 80%, preferably less than or equal to 70%.

Preferably, the stack is deposited by magnetron sputtering. According to this advantageous embodiment, all the layers of the stack are deposited by magnetron sputtering.

The invention also relates to the process for obtaining a material according to the invention, wherein the layers of the stack are deposited by magnetron sputtering.

Examples

Example 1

Preparation of the Substrates: Stack of thin layers

Stack of thin layers, defined below, are deposited on substrates made of clear soda-lime glass with a thickness of 6 mm.

In the example of the invention: the functional layer is either NbN or NiCrN; and the dielectric layers are based on silica nitride, doped with aluminum (Si3N4A1).

Table 1 lists the materials and thicknesses in nanometers for each layer or coating that forms the stacks as a function of their position with respect to the substrate bearing the stack (final line at the bottom of the table). The “Ref.” numbers correspond to the references from FIG. 1, for samples 1 and 2. As for the comparative samples, comparative sample 1 is constructed from the prior art reference Indian application of the present Applicant: 4163/KOLNP/2010; comparative sample 2 is constructed from the prior art reference EP0747329A1 and comparative sample 3 is constructed from the prior art reference WO2017160325.

Table 1 : Stack of thin layers

Solar Control and Optical Properties

Table 2 lists the main optical characteristics measured when the glazings are part of a monolithic glazing of 6 mm glass. For these monolithic glazings:

TL indicates: the light transmission in the visible region in %, measured according to the illuminant D65 Obs 2; a*T and b*T indicate the a* and b* colors in transmission in the L*a*b* system measured according to the illuminant D65 Obs 2 and measured perpendicularly to the glazing;

RG indicates: the light reflection in the visible region in %, measured according to the illuminant D65 Obs 2 on the glass side of the glazing; a*G and b*G indicate the a* and b* colors in reflection in the L*a*b* system measured according to the illuminant D65 Obs 2 on the glass side of the glazing and thus measured perpendicularly to the glazing;

RC indicates: the light reflection in the visible region in %, measured according to the illuminant D65 Obs 2 on the coating side of the glazing; a*C and b*C indicate the a* and b* colors in reflection in the L*a*b* system measured according to the illuminant D65 Obs 2 on the coating side of the glazing and thus measured perpendicularly to the glazing.

The main optical characteristics of the comparative samples 1 3 were constructed from the patent information present in the corresponding prior art references.

Table 2: Optical & Solar Control Properties

From Tables 1 & 2, for samples 1 and 2 constructed according to the present invention, it can be vividly seen that the positional change of the functional layers i.e., NbN and NiCrN positions in Fl and F2 is the only change between the stack configuration of sample 1 and 2, the light transmission value is not impacted. Whereas, external reflection (RG) of sample 2 increases by 7% (from 15.6% in sample 1 to 22.8% in sample 2) while the external aesthetic remains neutral. Similarly, internal reflection (RC) of sample 2 decreases by 4%. Thus for applications desiring a high external reflection and low internal reflection (RC), Fl should be comprised of NiCr or NiCrN and for applications desiring certain depth of aesthetic in external reflection (RG), Fl should be comprised of Nb or NbN. The material comprised in Fl of the thin layer of stack taught in the present invention is significant in determining the optical characteristics of the resultant solar control coated glass article.

On the contrary the comparative samples 1 and 2 comprising identical materials in Fl and F2 either NbN or NiCr, do not achieve internal reflection (RC) and external reflection (RG) values as that achieved by the samples prepared according to the present invention. It can also be seen that the internal reflection for these samples are always higher than the external reflection value. Although comparative sample 3 has internal reflection lower than external reflection, the invention comprises different materials in Fl and F2.

The primary reason for the difference between reflection level is the optical property of NiCr or NiCrNx compared with Niobium or Niobium nitride.

In order to demonstrate the role of dielectric coatings in the optical characteristics of the resultant products, samples 3 - 5 were constructed from the stack of thin layers, according to the present invention demonstrated in Table 3.

Table 3: Stack of thin layers

Table 4: Conditions of Dielectric Coatings

It can be seen that the comparative examples do not satisfy the conditions of the dielectric coatings as that taught by the present invention and hence do not also result in desired internal reflection and external reflection values as shown in Table 5.

Table 5: Optical Properties

It can be understood from Table 5 that the stack of thin layers constructed according to the teaching of the first major embodiment of the present invention has a ratio of internal reflection (RC) to external reflection (RG) not exceeding 1.2. Whereas none of the comparative samples satisfy this condition and have values that are much higher demonstrating that these stack configurations from prior art do not achieve the internal reflection (RC) to external reflection (RG) as that desired by the present invention.

Example 3

Positional Impact of Functional Layer Materials:

Stack of thin layers having the stack configuration as shown in table 6 were used to demonstrate the positional impact of NiCr / NiCrN in Fl on the internal reflection (RC).

Table 6: Stack of thin layers

The thickness of Ml in samples 6 & 7 were varied from 10 nm to 60 nm, while the thickness of M2 was maintained at 20 nm and thickness of M3 was maintained at 30 nm.

Internal reflection (RC) and external reflection (RG) values obtained for the different thickness values of Ml were plotted for samples 6 & 7 and the same is illustrated in FIG. 5.

Similarly, the thickness of M2 in samples 6 & 7 were varies from 10 nm to 60 nm, while the thickness of Ml was maintained at 10 nm and thickness of M3 was maintained at 30 nm. Internal reflection (RC) and external reflection (RG) values obtained for the different thickness values of M2 were plotted for samples 6 & 7 and the same is illustrated in FIG. 6.

Likewise, the thickness of M3 in samples 6 & 7 were varies from 10 nm to 60 nm, while the thickness of Ml was maintained at 10 nm and thickness of M2 was maintained at 30 nm. Internal reflection (RC) and external reflection (RG) values obtained for the different thickness values of M3 were plotted for samples 6 & 7 and the same is illustrated in FIG. 7.

From FIG. 5, FIG. 6 and FIG. 7, it can be understood that external reflection (RG) of sample 6 is always high and the internal reflection (RC) is always low. Hence, sample 6 which has Fl comprised of NiCrN is advantageous if low internal reflection (RC) and high external reflection (RG) values are desired. Alternatively, if low external reflection (RG) and slightly higher internal reflection (RC) is desired then it is advantageous to have Fl comprised of Nb or NbN.

Further to reaffirm the above understanding and to study if thickness variations in Fl and F2 materials will reverse this reverse the above obtained optical characteristics, the thickness of Ml, M2 and M3 were fixed at 20 nm, 20 nm and 30 nm, respectively and the thickness of Fl and F2 were varied. At the first instance, the thickness of NbN in samples 6 & 7 was fixed at 1 nm and the thickness of NiCrN in samples 6 & 7 was varied from 0.5 nm to 10 nm and the corresponding internal reflection (RC) and external reflection (RG) values obtained were plotted and shown in FIG. 8. FIG. 8 demonstrates the influence of varying thicknesses of NiCrN on RG and RC values of samples 6 and 7. Further, the influence of varying thicknesses of NiCrN on color variation of a*G and b*G was also plotted and shown in FIG. 9

In the second instance, the thickness of NiCrN in samples 6 & 7 was fixed at 3.5 nm and the thickness of NbN in samples 6 & 7 was varied from 0.5 nm to 10 nm and the corresponding internal reflection (RC) and external reflection (RG) values obtained were plotted and shown in FIG. 10. FIG. 10 demonstrates the influence of varying thicknesses of NbN on RG and RC values of samples 6 and 7. Further, the influence of varying thicknesses of NbN on color variation of a*G and b*G was also plotted and shown in FIG. 11.

From FIG. 8 it can be understood that internal reflection (RC) varies significantly for sample 6. This is because when NiCrN layer is placed in close proximity to the glass substrate, internal reflection (RC) decreases significantly. On the contrary this effect is not very prominent in FIG. 10. Thus positioning NiCrN in close proximity to the glass substrate is significantly better than otherwise. However, if a lower external reflection (RG) is desired then it is advantageous to place NiCrN in F2 as demonstrated by sample 7.

Lastly, from FIG. 9 it can be seen that samples 6 has significantly reduced color variation, for varying thicknesses of NiCrN in Fl. Whereas for varying thicknesses of NbN, the color variation is irrespective of the position of NbN in Fl or F2.

Industrial Applicability

The solar control glass article described in the present disclosure finds application as a glazed element in building. In this application case, the glazing may form a monolithic glazing with the coating side of the glass arranged facing the closed space inside the building. The glazing may also form a laminated glazing whose stack of layers may be in contact with the thermoplastic adhesive material connecting the substrates, in general PVB. The glazing may also be part of an insulation glazing window. The glazing of the present disclosure can also be annealed, strengthened, toughened and/or tempered.

The tempered glazing can also be used in building wall cladding panel of curtain walling for interior applications. Further an also be used as a side window, rear window or sunroof for an automobile or other vehicle.

Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed is not necessarily the order in which they are performed. Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.

The specification and illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The specification and illustrations are not intended to serve as an exhaustive and comprehensive description of all of the elements and features of apparatus and systems that use the structures or methods described herein. Certain features, that are for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in a sub combination. Further, reference to values stated in ranges includes each and every value within that range. Many other embodiments may be apparent to skilled artisans only after reading this specification. Other embodiments may be used and derived from the disclosure, such that a structural substitution, logical substitution, or another change may be made without departing from the scope of the disclosure. Accordingly, the disclosure is to be regarded as illustrative rather than restrictive.

The description in combination with the figures is provided to assist in understanding the teachings disclosed herein, is provided to assist in describing the teachings, and should not be interpreted as a limitation on the scope or applicability of the teachings. However, other teachings can certainly be used in this application.

As used herein, the terms "comprises," "comprising, " "Iincludes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Also, the use of "a" or "an" is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural, or vice versa, unless it is clear that it is meant otherwise. For example, when a single item is described herein, more than one item may be used in place of a single item. Similarly, where more than one item is described herein, a single item may be substituted for that more than one item.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent that certain details regarding specific materials and processing acts are not described, such details may include conventional approaches, which may be found in reference books and other sources within the manufacturing arts.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

List of Elements

TITLE: A SOLAR CONTROL GLASS ARTICLE WITH VARIABLE OPTICAL

PROPERTIES

10 Glass Substrate

20 First Dielectric Layer Ml

40 Second Dielectric Layer M2

50 First Functional Layer Fl

80 Third Dielectric Layer M3

100 Second Functional Layer F2

100 Overcoat Layer

Claims

1) A solar control glass article comprising a transparent substrate having a first surface provided with a thin multilayer coating comprising: n functional layers and n+1 dielectric layers, wherein n=2 such that each functional layer is sandwiched between 2 dielectric layers and optionally an overcoat layer, wherein the overcoat layer forms the outermost layer of the thin multilayer coating, characterized in that: when the first functional layer (Fl) comprises NiCr or NiCrN having a thickness range of 0.1 nm to 30 nm; and the second functional layer (F2) comprises Nb or NbN having a thickness range of 2 nm to 35 nm, said solar control glass article has an internal reflection (RC) of less than 15% and a ratio of said internal reflection (RC) to external reflection (RG) not exceeding 1.2; and when the first functional layer (Fl) comprises Nb or NbN having a thickness range of 0.1 nm to 30 nm; and the second functional layer (F2) comprises NiCr or NiCrN having a thickness range of 0.1 nm to 35 nm, said solar control glass article has an external reflection (RG) of less than 30% and a ratio of said external reflection (RG) to internal reflection (RC) not exceeding 1.2.

2) The solar control glass article as claimed in claim 1 has external reflection values of a*G ranging between -15 to +5 and b*G ranging between -20 to +20, when (Fl) comprises NiCr or NiCrN and (F2) comprises Nb or NbN.

3) The solar control glass article as claimed in claim 1 has internal reflection (RC) less than external reflection (RG), when (Fl) comprises NiCr or NiCrN and (F2) comprises Nb or NbN.

4) The solar control glass article as claimed in claim 1 has internal reflection values of a*G ranging between -25 to +25 and b*G ranging between -50 to +50, when (Fl) comprises Nb or NbN and (F2) comprises NiCr or NiCrN. 5) The solar control glass article as claimed in claim 1 has external reflection (RG) less than internal reflection (RC), when (Fl) comprises Nb orNbN and (F2) comprises NiCr or NiCrN.

6) The solar control glass article as claimed in claim 1 , wherein the total physical thickness of the dielectric layers is less than or equal to 150 nm.

7) The solar control glass article as claimed in claim 1, wherein the dielectric layer comprises a material selected from the group consisting of silicon nitride, titanium nitride, aluminum nitride, oxynitrides of silicon and aluminum, silicon aluminium nitride, zinc oxide, tin and zinc oxide, tin oxide, titanium oxide, silicon oxide, aluminum oxide or titanium and tin oxide.

8) The solar control glass article as claimed in claim 1, wherein the dielectric layer comprises silicon nitride.

9) The solar control glass article as claimed in claim 8, wherein the dielectric layer comprising silicon nitride is doped with aluminum.

10) The solar control glass article as claimed in claim 1 has a visible light transmission (TL) ranging between 5% and 60%.

11) The solar control glass article as claimed in claim 1, wherein the overcoat comprises titanium zirconium nitride or oxynitride, zirconium oxide or titanium oxide or their combinations thereof.

12) The solar control glass article as claimed in claim 1, wherein the first dielectric layer has a physical thickness ranging between 1 nm and 100 nm.

13) The solar control glass article as claimed in claim 1, wherein the second dielectric layer has a physical thickness of less than or equal to 65 nm.

14) The solar control glass article as claimed in claim 1, wherein the third dielectric layer has a physical thickness ranging between 20 nm and 60 nm. 15) The solar control glass article as claimed in claim 13, wherein the second dielectric layer is absent.

16) The solar control glass article as claimed in claim 1, wherein a thickness ratio of the first dielectric layer/third dielectric layer is less than or equal to 2, when (Fl) comprises NiCr or NiCrN and (F2) comprises Nb or NbN.

17) The solar control glass article as claimed in claim 1, wherein a thickness ratio of the first dielectric layer/third dielectric layer is less than or equal to 4, when (Fl) comprises Nb or NbN and (F2) comprises NiCr or NiCrN.

18) The solar control glass article as claimed in claim 1, further comprises barrier layers flanking one or both of the functional layers.

19) The solar control glass article as claimed in claim 18, wherein the barrier layer comprises Ti or Nb or SiAl or SiNx.

20) The solar control glass article as claimed in claim 18, wherein the barrier layer has a thickness ranging between 0.1 nm and 5 nm.

21) The solar control glass article as claimed in claim 1 is heat treatable and has a superior color matchability with a AE* of less than 4.0 for external reflection and transmission.

22) The solar control glass article as claimed in claim 1, wherein the dielectric layer farthest from the glass substrate comprises a metal oxide.

23) The solar control glass article as claimed in claim 22, wherein the dielectric layer farthest from the glass substrate comprises a metal oxide selected from the group consisting of TiO_x, TiZrO_x, NbO_x or SiO_x.

24) The solar control glass article as claimed in claim 1 is not heat treated.

25) The solar control glass article as claimed in claim 1, wherein one or both functional layers are partially oxidized. 26) The solar control glass article as claimed in any of the preceding claims is a monolithic window.

27) The solar control glass article as claimed in any of the preceding claims is an insulation glazing window.