WO2020012502A1

WO2020012502A1 - Solar control glass articles

Info

Publication number: WO2020012502A1
Application number: PCT/IN2019/050510
Authority: WO
Inventors: Soumyadeep MISRA; Arpan BASU; Shrijit Sudhir KULKARNI
Original assignee: Saint-Gobain Glass France
Priority date: 2018-07-12
Filing date: 2019-07-10
Publication date: 2020-01-16
Also published as: CO2020016528A2; EP3821283A1; EP3821283A4; MX2021000406A; PH12020552198A1

Abstract

A heat treatable solar control glass article (100) having rose or copper color glass side reflection comprising a transparent glass substrate (110) provided with a multilayer coating (200) having solar control properties is disclosed. The multilayer coating (200) comprises of one or more nickel or niobium alloy nitride functional layers (120), each sandwiched between two transparent dielectric layers (130a, 130b). The thickness of the dielectric layer (130b) provided above the functional layer (120) is greater than 100 nm and less than 160 nm and that of the dielectric layer (130a) provided above the transparent glass substrate (110) is greater than 5 nm and less than 20 nm. The heat treatable solar control glass article (100) exhibits rose or copper colored reflection on the side opposite to the side provided with the multilayer coating (200).

Description

SOLAR CONTROL GLASS ARTICLES

Technical Field

The present disclosure relates, in general to a coated glass article, and more specifically to a heat treatable solar control glass article having a rose or copper colored external reflection.

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. Residential and non-residential buildings that use more energy than necessary to stay cool are a major source of unnecessary C0₂ emissions. Cutting down on needless C0₂ is the need of the hour and solar control glass comes as a good news in this respect. Engineering microscopically thin multilayer coatings for producing such solar control glass are known in the art.

Color matchability of such coated solar control glass article

(before heat treatment vs. after heat treatment) is also the need of the hour, where large quantities of glass article are produced, cut to desirable sizes and heat treated for safety. In such cases it is often desirable that the heat treated articles match their non-heat treated counterparts with regard to color, reflectance, transmittance and the like for architectural and aesthetic purposes.

Solar control coatings having a layer stack of glass/Si3N4/NiCr/Si₃N4 are known in the art, where the metallic NiCr layer is the sole infrared (IR) reflecting layer in the coating. In certain instances, the NiCr IR reflecting layer may be nitrided. While such layer stacks provide efficient solar control and low DE* values (more color matchability), the reflection color obtained by such layer stacks has never been worked upon. For example, a known solar control coating having a layer stack of glass/Si₃N4/NiCrN/Si₃N4 has an external a* value in a range between -8 to +2; and b* value in a range between -2 to +8. This implies that a glass article with the above solar control layer stack would have a neutral or green or yellow green color in external reflection. Referring to U.S. patent number 6926967 describes a heat treatable coated article with NiCrN acting as the IR reflecting layer. While the invention relates to achieving approximately the same color characteristics as viewed by the naked eye before and after heat treatment, the external reflection color obtained by the coated articles is not explicitly disclosed. The glass article coated with the solar control coating has an external glass side a* value ranging between 0 to -2.5 and b* value ranging between 0 to 3; and transmission a* value ranging between 0 to 2 and b* value ranging between -3 to -9. The examples described in the patent disclose rather the color change (DE*) after heat treatment. However, a glass article having an external a* and b* value equal to 0 would exhibit a neutral color and a glass article having an external a* and b* equal to -2.5 and 3, respectively would exhibit a slight greenish yellow color.

Referring to PCT publication number 2017144828 owned by the assignee of the present disclosure, relates to a laminated glazing provided with a stack of thin layers for solar control comprising the layers Si₃N₄/ NiCrN/ Si₃N₄ on the surface of the glass. The glazing is reported to have a neutral reflectance to not cause any inconvenience to the users.

Notwithstanding all the past experiences and technologies which are available for producing solar control articles, it has been discovered that although these coated articles are effective in solar control and have more color matchability, the layer stack was never engineered to have different reflection colors. Hence there is scope for obtaining different reflection color while retaining their solar control properties and low DE* value. For example, most of the solar control glass articles available currently in the market have a neutral or greenish yellow color in external reflection. A study on the emerging market trends revealed that this neutral/greenish color is not to everyone's liking and may not be appropriate for every kind of building. Since these solar control articles are generally more expensive than their ordinary counterparts, it becomes more important to ensure that the extra cost is justified by multiple combined features of the coated articles. Further, it has been found that the color of the external and internal refection of these coated articles can be improved upon by working on the dielectric layers of the solar control layer stack. The external reflection of the solar control coated articles can be varied by varying the coating thickness of the S13N4 layers of the solar control layer stack which unfortunately result in undesirable interferences in the multilayer coating.

The present disclosure relates to a heat treatable solar control glass article that comprises of a thin multilayer stack comprising an alloy nitride functional layer sandwiched between two transparent dielectric layers provided on one side of a transparent substrate. The thickness of the alloy nitride functional layer and the dielectric layer is designed in such a way that it gives rose or copper colored external appearance on the other side of the transparent substrate while retaining its solar control properties and low DE* value, without undue interferences to the other properties of the multilayer stack. Thus these coatings can block part of the solar spectra very efficiently in addition to having a rose or copper colored appearance from outside the building. Further the coated articles may be used as heat-treated and non-heat-treated articles and when heat- treated exhibit a high color matchability to their non-heat-treated counterparts. The light transmission from exterior to interior of a building incorporated with these heat treatable solar control glass articles is also decreased thereby reducing glare for the building occupants.

Summary of the Disclosure

In one aspect of the present disclosure, a heat treatable solar control glass article having rose or copper color glass side reflection comprising a transparent substrate having a first surface provided with a thin multilayer coating is provided. The multilayer coating comprises of one or more nickel or niobium alloy nitride functional layers, each sandwiched between two transparent dielectric layers. The thickness of the dielectric layer provided above the functional layer is greater than 100 nm and less than 160 nm and that of the dielectric layer provided above the transparent substrate is greater than 10 nm and less than 40 nm. 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 heat treatable solar control glass article, according to one embodiment of the present disclosure;

FIG. 1A illustrates a heat treatable solar control glass article, according to another embodiment of the present disclosure;

FIG. 2 illustrates a transparent substrate, according to one embodiment of the present disclosure; and

FIG. 3 illustrates a rose or copper colored solar control glass article, according to another embodiment of the present disclosure.

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 heat treatable solar control glass articles having rose or copper color glass side reflection.

A heat treatable solar control glass article 100 according to one embodiment of the present disclosure is illustrated in FIG. 1. The heat treatable solar control glass article 100 comprises of a glass substrate 110 provided with a multilayer coating 200. The multilayer coating 200 comprises of at least one nickel or niobium alloy nitride functional layer 120, each sandwiched between two transparent dielectric layers l30a, l30b. The dielectric layer l30a is in direct contact with the glass substrate 110 and the dielectric layer l30b is provided above the alloy nitride functional layer 120.

The alloy nitride functional layer 120 comprises at least one nitride of a metal alloy selected from the group consisting of NbCr, NiCr, NiCrMo and NbZr. In a specific embodiment, the alloy nitride functional layer 120 comprises of nickel, chromium and nitrogen. The transparent dielectric layers l30a, l30b are based on aluminium nitride, aluminium oxynitride, silicon nitride or silicon oxynitride or silicon aluminium nitride, tin oxide, a mixed oxide of zinc and tin or titanium oxide. In a specific embodiment, the transparent dielectric layers l30a, l30b is silicon nitride.

Optionally, the multilayer coating 200 may further comprise an overlayer 140 provided above the transparent dielectric layer (l30b). FIG. 1A illustrates heat treatable solar control glass article 100 according to one other embodiment of the present disclosure. The overlayer 140 comprises of at least one metal oxide selected from the group consisting of titanium, chromium or zirconium or their alloy or combination thereof. The overlayer 140 if present improves the mechanical durability of the multilayer coating 200 such as scratch resistance etc. However, the optical properties of the multilayer coating 200 remain unchanged.

In one embodiment of the present disclosure, the thickness of the nickel or niobium alloy nitride functional layer 120 is greater than 5 nm and less than 20 nm. The thickness of the nickel or niobium alloy nitride functional layer 120 is adjusted to obtain a desired light transmission through the heat treatable solar control glass article 100. In another embodiment of the present disclosure, the thickness of the transparent dielectric layers l30a, l30b is adjusted to optimize the reflectance and color of the transparent glass substrate 110. In one embodiment, the thickness of the dielectric layer l30b provided above the nickel or niobium alloy nitride functional layer 120 is greater than 100 nm and less than 160 nm and the thickness of the dielectric layer l30a in direct contact with the glass substrate 110 is greater than 10 nm and less than 40 nm. The increased thickness of the dielectric layer l30b results in a positive a* and b* values (measured on the glass side G) ranging between (+ 8 and +12) and (+2 and +12), respectively.

In one embodiment, the multilayer coating 200 is applied on the transparent glass substrate 110 by physical vapor deposition using magnetron sputtering. In alternate embodiments, other suitable coating techniques may be used to obtain multilayer coating 200.

The inventors of the present disclosure discovered that the external reflection of such solar control glass articles can be varied by varying the thickness of the dielectric layers l30a, l30b. More particularly, it surprisingly and unexpectedly has been discovered that engineering thickness of these dielectric layers l30a, l30b obtained an aesthetically improved solar control glass articles that retained their solar control properties and other performance properties. FIG. 2 illustrates a glass substrate 110 provided with the multilayer coating 200 of the present disclosure. In multiple embodiments, the glass substrate 110 may be a clear glass or a tinted glass. The multilayer coating 200 is provided on the coating side (C) 203 of the transparent substrate 110. When the heat treatable solar control glass article 100 of the present disclosure is installed in a building the coating side 203 provided with the multilayer coating 200 faces the inside of a building

In such an arrangement, the glass side (G) 202 opposite to the coating side (C) 203 of the transparent substrate 110 exhibits a rose color reflection or a copper color reflection depending on the thickness of the dielectric layer l30a, 130b when viewed from outside the building.

The thickness of the dielectric layer l30b provided above the nickel or niobium alloy nitride functional layer 120 is increased to increase the a* value (measured on the glass side G) of the heat treatable solar control glass article 100. A positive a* (a*G~l0) value gives a reddish appearance on the glass side (G) 202 opposite to the coating side (C) 203 (provided with the multilayer coating 200) of the transparent substrate 110 which contributes to the rose/ copper color reflection of the heat treatable solar control glass article 100 on the glass side (G) 202. Similarly, b* value (measured on the glass side G) is also engineered to be a positive value. A positive b* value (b*G~3) in combination with a positive a* value (preferably, a*G>b*G) results in rose color reflection of the heat treatable solar control glass article 100 on the glass side (G) 202. Likewise, b* value (b*G~l0) in combination with a positive a* value (preferably, a*G>b*G) results in copper color reflection of the heat treatable solar control glass article 100 on the glass side 202. The light transmission of the heat treatable solar control glass article 100 ranges between 10% and 60% depending on the thickness of alloy nitride functional layer 120.

A heat treatable solar control glass article having rose or copper colored external reflection 300 according to one specific embodiment is illustrated in FIG. 3. The heat treatable solar control glass article having rose or copper colored external reflection 300 comprises of a transparent glass substrate 110 provided with a multilayer coating 200 comprising a nickel chromium nitride layer 302 sandwiched between two transparent dielectric layers 303a, 303b based on silicon nitride. The thickness of the nickel chromium nitride layer 302 ranges between 5 nm and 20 nm. The nickel chromium nitride layer 302 acts as the IR blocking layer of the multilayer coating 200 and attributes to the solar control properties of the heat treatable solar control glass article having rose or copper colored external reflection 300.

While the solar control properties depend entirely on the thickness of the nickel chromium nitride layer 302, the light transmission (TL) of the heat treatable solar control glass article having rose or copper colored external reflection 300 is invariably proportional to the thickness of the nickel chromium nitride layer 302. Hence it becomes important to have a balance between the solar control properties and the light transmission (TL) values of the heat treatable solar control glass article having rose or copper colored external reflection 300. Thus a thickness range between 5 nm and 20 nm of the nickel chromium nitride layer 302 provides for the desired light transmission (TL) while also maintaining the solar control properties of the heat treatable solar control glass article having rose or copper colored external reflection 300. The thickness of the silicon nitride layer 303a present above the transparent glass substrate 110 ranges between 10 nm and 40 nm and the thickness of the silicon nitride layer 303b present above the nickel chromium nitride layer 302 ranges between 100 nm and 160 nm. The silicon nitride dielectric layer 303a, 303b contribute to the reflection color of the heat treatable solar control glass article having rose or copper colored external reflection 300 and hence are designed in such a way that the glass side G of the transparent glass substrate 110 reflects a rose color or copper color. Consequently, the coating side C of the transparent glass substrate 110 reflects a greenish yellow color. The multilayer coating 200 has -10% external reflection and provides a very subtle appearance. In one aspect of the embodiment, the heat treatable solar control glass article having rose or copper colored external reflection 300 may be enameled. In multiple aspects of the embodiment, the heat treatable solar control glass article having rose or copper colored external reflection 300 may be strengthened, toughened or heated to a temperature ranging between 500 °C and 750 °C.

The multilayer coating 200 is heat treatable and the transparent glass substrate 110 coated with the multilayer coating 200 can be heat treated to a temperature as high as 630 °C for about 9 minutes. The DE* value (change in color of the heat treatable solar control glass article having rose or copper colored external reflection 300 before and after heat treatment) is less than 3.5. The emissivity of the heat treatable solar control glass article having rose or copper colored external reflection 300 gets reduced slightly after heat treatment. The heat treated solar control glass article having rose or copper colored external reflection exhibits a higher IR reflection compared to standard glass. The heat treatable solar control glass article 300 having rose or copper colored external reflection and the heat treated solar control glass article 300 having rose or copper colored external reflection exhibit high durability values.

In one embodiment of the present disclosure, a composite glazing comprising a plurality of glass substrates bonded together by a polymeric interlayer is disclosed. One or more glass substrates of the plurality of glass substrates can be a rose or copper colored solar control glass article 300 or a heat treated rose or copper colored solar control glass article. In one aspect of the embodiment, the polymeric interlayer is made of polyvinyl butyral (PVB) and/or other organic polymers selected from the group consisting of polyurethane and/or ethylvinylacetate (EVA) and/or polyvinyl chloride and/or polyester and/or polyethylenevinylacetate (PET) and/or polycarbonate and/or polypropylene and/or polyethylene and/or polyurethacrylate or their combinations thereof.

In the following examples, the layer stacks were deposited by magnetically enhanced (magnetron) sputtering at room temperature on a transparent glass substrate having a thickness of 6 mm.

Example 1

Rose Colored Solar Control Glass Article

A clear glass substrate and a green tinted glass substrate were coated with the below shown layer stacks:

Layer Stack 1: Glass // Si₃N₄ (33 nm )/ NiCrN_x (9 nm )/ Si₃N₄ (141 nm)

Optical properties of the glass sample coated with layer stack 1 is summarized in Table 1.

Table 1: Optical Properties of Rose Colored Solar Control Glass Article

R_ext=External reflection; a*G, b*G=a*, b* values measured on the external side, i.e., the glass side; Ri_nt=Internal reflection; a*C, b*C=a*, b* values measured on the internal side, i.e., the coating side

The layer stack 1 exhibited a rose colored appearance on the glass side (that is on the building exterior) and a greenish yellow color on the coating side (that is on the building interior) when provided on a clear glass substrate. When the layer stack 1 was provided on a green tinted glass substrate, although the glass side reflection of the coated glass substrate appears reddish, the desired rose color reflection was better obtained while using a clear glass substrate. It was evident that layer stack 1 having a decreased NiCrN_x thickness recorded a light transmission (T_L) of 31%. Transparent glass has an emissivity of 89%, whereas the rose colored solar control glass article according to the embodiment of the present disclosure has an emissivity as less as 60%. The brightness of the external color reflected by the coated glass substrates may be varied by varying the reflection values (R_ext).

Example 2

Copper Colored Solar Control Glass Article

A glass substrate was coated with the below shown layer stacks: Layer Stack 2: Glass // Si₃N₄ (33 nm)/ NiCrN_x (11.4 nm )/ Si₃N₄ (134.4 nm)

Optical properties of the glass sample coated with layer stack 2 is summarized in Table 2.

Table 2: Optical Properties of Copper Colored Solar Control Glass Article

Glass substrates coated with layer stack 2 exhibited a copper colored appearance on the glass side (G). The internal reflection (Rmt) was found to be high at 38%. However, the external reflection (R_ext) is lower making the reflection color of the heat treatable solar control glass subtle in appearance. The brightness of the external color reflected by the coated glass substrates may be varied by varying the reflection values (R_ext).

Example 3

Heat Treatment The glass substrates coated with layer stacks 1 and 2 were subjected to heat treatment at 630 °C for about 9 minutes and the change in internal color, external color and transmission values before and after heat treatment were measured and are tabulated in table 3. It is evident from the table that both the layer stacks 1 and 2 have DE* values less than or equal to 3.5 in both color and transmittance. This property brings high color matchability between the rose or copper colored solar control glass article 300 and the heat treated rose or copper colored solar control glass article.

Table 3: Change in Color and Transmittance

Further the sheet resistance and emissivity values of glass substrates provided with layer stacks 1 and 2 were measured both before and after heat treatment (HT) and the results are tabulated in table 4. It is evident that after tempering the sheet resistance and emissivity of layer stacks 1 and 2 were reduced. This indicated that the material is a better IR reflector after tempering.

Table 4: Sheet Resistance and Emissivity Measurements

*HT Heat treatment

Durability Studies

The following durability studies were performed for the glass substrates coated with layer stack 1 and 2.

Erichsen Brush Test The brush test was used to evaluate the resistance of the layer stacks to erosion caused by scrubbing. In this test a soft brush is rubbed against the coating where the coating is submerged in the water. This test is done to test mechanical robustness against washing machine brushes during processing.

The samples were tempered at a temperature of 630 °C after the

Erichsen brush test. This step reveals the presence of any minor scratches that occurred during the test procedure. However, the tested samples did not show any sign of scratches.

In another experiment, the samples coated with layer stack 1 and layer stack 2 were first tempered at a temperature above 630 °C and then subjected to the Erichsen brush test procedure. Again the samples did not show any sign of minor scratch or coating erosion.

Taber Abrasion test

Taber abrasion test was used for performing accelerated wear resistance testing. It involved mounting a flat sample of approximately 100 mm² to a turntable platform that rotate on a vertical axis at a fixed speed. The wear action was carried out by two rotating abrading wheels supported on a loading arm which applied 250 grams pressure against the specimen, exclusive of the weight of the wheel in contact with sample. The transmission before and after the test were measured to calculate the overall change in transmission of the test samples. The results of mechanical durability studies are summarized in Table 5.

Table 5: Results of Durability Studies

It should be noted that the above examples are only indicative and were incorporated in the specification for teaching purpose only and further does not limit the scope of the invention in any manner.

Comparative Example 1

Clear glass substrates were coated with the below shown layer stacks:

Layer Stack 3: Glass// S13N4 (33 nm )/ NiCrNx (9 nm )/ S13N4 (95 nm)

Layer Stack 4: Glass// S13N4 (33 nm)/ NiCrN_x (9 nm)/ S13N4 (165 nm)

Optical properties of the glass sample coated with layer stacks 3, 4

& 5 are summarized in Table 6.

Table 6: Optical Properties of Coated Solar Control Glass Articles

Glass substrate coated with layer stack 3 showed yellow color reflection from its b*G value and therefore exhibited a golden color external reflection. Similarly glass substrate coated with layer stack 4 exhibited a purple color external reflection. These external reflection colors are not desired and are reasoned to be the result of the dielectric layer present above the functional layer having thicknesses below the lower limit and above the higher limit of the desired thickness range described in the teachings of the present disclosure.

Industrial Applicability

The heat treatable solar control glass article 100 of the present disclosure can be used in a monolithic, double or triple glazing. These glazings are installed in such a way that the multilayer coating is preferably on face 2, the faces of substrates being numbered from outside to the inside of the building or room which is equipped therewith, giving it a solar radiation protection effect. These glazings exhibit an emissivity value equal to or less than 80%. The heat treatable solar control glass article 100 can also be used in building wall cladding panel of curtain walling for interior applications. Further the heat treatable solar control glass article 100 can also be used as a side window, rear window or sunroof for an automobile or other vehicle.

The heat treatable solar control glass article 100 of the present disclosure can also be enameled, strengthened or toughened and used for building interior applications. The durability studies of these heat treatable solar control glass article 100 provide for a longer life of these articles. Further the heat treatable solar control glass article 100 because of its solar control property and aesthetically improved appearance could also be used as side window, rear window or sunroof for an automobile or other vehicles. Furthermore, the heat treatable solar control glass article 100 of the present disclosure can be used to produce composite glazing viz. laminated glazing and additionally has the advantage of being able to be used as annealed, heat strengthened and tempered glass articles.

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," "includes," "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: SOLAR CONTROL GLASS ARTICLES

100 Heat Treatable Solar Control Glass Article

110 Glass Substrate

120 Alloy Nitride Functional Layer

l30a Dielectric Layer

130b Dielectric Layer

140 Overlayer

200 Multilayer Coating

202 Glass Side (G)

203 Coating Side (C)

300 Heat Treatable Solar Control Glass Article having Rose or Copper Colored External Reflection

302 Nickel Chromium Nitride Layer

303a Silicon nitride Layer

303b Silicon nitride Layer

Claims

We claim,

1) A heat treatable solar control glass article 100 having rose or copper color glass side reflection comprising:

a transparent glass substrate 110 having a first surface provided with a thin multilayer coating 200 comprising:

one or more Ni or Nb alloy nitride functional layers 120, each sandwiched between two transparent dielectric layers l30a, l30b,

wherein the thickness of the dielectric layer l30b provided above the functional layer 120 is greater than 100 nm and less than 160 nm and that of the dielectric layer l30a provided above the transparent substrate 110 is greater than 10 nm and less than 40 nm.

2) The heat treatable solar control glass article 100 as claimed in claim 1, wherein the functional layer 120 comprises of at least one nitride of a metal alloy selected from NbCr, NiCr, NiCrMo and NbZr.

3) The heat treatable solar control glass article 100 as claimed in claim 1, wherein the transparent dielectric layers l30a, l30b are based on aluminium nitride, aluminium oxynitride, silicon nitride, silicon oxynitride, silicon aluminium nitride, tin oxide, a mixed oxide of zinc and tin or titanium oxide.

4) The heat treatable solar control glass article 100 as claimed in claim 1, wherein the thickness of the transparent dielectric layers l30a, l30b are adjusted to optimize the reflectance and color of the transparent substrate 110 on the side opposite to the side provided with the multilayer coating. 5) The heat treatable solar control glass article 100 as claimed in claim 1, wherein the thickness of the functional layer 120 is greater than 5 nm and less than 20 nm.

6) The heat treatable solar control glass article 100 as claimed in claim 1, wherein the multilayer coating 200 is applied on the coating side 203 of the transparent glass substrate 110.

7) The heat treatable solar control glass article 100 as claimed in claim 1, wherein the thickness of the functional layer 120 and the thickness of the transparent dielectric layers l30a, l30b are adjusted to give a rose colored reflection on a surface opposite to the first surface of the transparent glass substrate 110 provided with a thin multilayer coating 200.

8) The heat treatable solar control glass article 100 as claimed in claim 1, wherein the thickness of the functional layer 120 and the thickness of the transparent dielectric layers l30a, l30b are adjusted to give a copper colored reflection on a surface opposite to the first surface of the transparent glass substrate 110 provided with a thin multilayer coating 200.

9) The heat treatable solar control glass article 100 as claimed in claim 1, wherein the thin multilayer coating 200 optionally comprises an overlayer 140 provided above the functional layer 120.

10) The heat treatable solar control glass article 100 as claimed in claim 10, wherein the overlayer 140 comprises of at least one metal oxide selected from the group consisting of titanium, chromium or zirconium or their alloy or combination thereof. 11) The heat treatable solar control glass article 100 as claimed in claim 1, wherein the transparent glass substrate 110 is made of clear glass or tinted glass.

12) The heat treatable solar control glass article 100 as claimed in claim 1, wherein the heat treatment involves heating to a temperature above 500 °C and below 750 °C to obtain a heat treated solar control glass article.

13) A heat treated solar control glass article as claimed in claim 12 having a AE* less than or equal to 3.5 on the air side and the side opposite to the air side.

14) The heat treatable solar control glass article 100 as claimed in claim 1 having a light transmittance ranging between 10 % to 60%.

15) The heat treatable solar control glass article 100 as claimed in claim 1 can be enameled.

16) A composite glazing comprising:

a plurality of glass substrates, wherein at least one glass substrate comprises a multilayer coating 200 having solar control properties as claimed in claim 1 ; and

at least one polymeric interlayer configured to bond the plurality of glass substrates.

17) A composite glazing comprising:

a plurality of glass substrates, wherein at least one glass substrate comprises a heat treated solar control glass article as claimed in claim 12 or 15; and

at least one polymeric interlayer configured to bond the plurality of glass substrates. 18) The composite glazing as claimed in claim 16 or 17, wherein the polymeric interlayer is made of polyvinyl butyral (PVB) and/or other organic polymers selected from the group consisting of polyurethane and/or ethylvinylacetate (EVA) and/or polyvinyl chloride and/or polyester and/or polyethylenevinylacetate (PET) and/or polycarbonate and/or polypropylene and/or polyethylene and/or polyurethacrylate or their combinations thereof.

19) A monolithic glazing or double glazing incorporating the transparent glass substrate 110 as claimed in claim 1 or a heat treated glass article as claimed in claim 12 or 15, the multilayer coating 200 preferably on face 2, the faces of substrates being numbered from outside to the inside of the building or room which is equipped therewith, giving it a solar radiation protection effect.

20) The monolithic glazing or double glazing as claimed in claim 19 having an emissivity value equal to or less than 80%.

21) The monolithic glazing or double glazing as claimed in claim 19 having a solar factor less than or equal to 0.6.

22) A building wall cladding panel of curtain walling comprising the transparent substrate 110 as claimed in claim 1 or a heat treated glass article as claimed in claim 12 or 15.

23) Side window, rear window or sunroof for an automobile or other vehicle formed by incorporating a transparent substrate 110 as claimed in claim 1 or a heat treated glass article as claimed in claim 12 or 15.