EP3856692A1

EP3856692A1 - A patterned functionally coated glass article

Info

Publication number: EP3856692A1
Application number: EP19865563.1A
Authority: EP
Inventors: Biplab Kumar Roy; Arpan BASU; Subhashree Venkatesh RUPANGUDI; Hemant RATHOD; Krishnamoorthy DURAISWAMY
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: 2018-09-28
Filing date: 2019-09-20
Publication date: 2021-08-04
Also published as: EP3856692A4; WO2020065664A1

Abstract

A patterned functionally coated glass article is provided. The patterned functionally coated glass article comprises of a glass substrate provided with a hybrid coating comprising an enamel layer provided directly over the surface of the glass substrate in a form of a pattern and a performance coating overlying the enamel layer and the glass substrate. The hybrid coating imparts variegated functionalities to the glass substrate such as solar control, low-emissivity, anti-reflectivity and/or reflectivity. The patterned functionally coated glass article can be handled before heat treatment and has optimized Daylight Glare Probability (DGP). The present disclosure further relates to a method of making the patterned functionally coated glass article using a hybrid coating technology involving both wet-coating technique and sputtering technique.

Description

A PATTERNED FUNCTIONALLY COATED GLASS ARTICLE

Technical Field

The present disclosure relates in general to a coated glass article and more particularly to a patterned functionally coated glass article that provides both a patterned surface as well as variegated functionalities to the glass substrate.

Background

Patterned glasses have one of their surfaces feature a design created by screen printing or other relevant printing technique. Patterned glasses are clear or tinted glasses printed with ceramic ink designs and subsequently heat treated. The heat treatment fires the ceramic paint into the glass surface. Such patterned glasses of varied colors and designs that fully or partially cover the surface of the glass are available in the market. The ceramic coverage on the patterned glass helps to control heat and transmission. Further there can be also provided on the surface of such patterned glass a magnetron coating that imparts functionalities such as solar control to the glass. Thus a resultant glass product has strength, privacy, decoration and solar control properties.

Such patterned glasses can be used in a wide variety of applications including doors, bus shelters, telephone kiosks, display signs etc., in addition to the more traditional glazing of partitions, windows and facades. These products combine aesthetics and functional performance for use in partitions, roof glazing and external walls. They can provide dramatic decorative effects or simple designs for privacy or solar control.

Currently, glass substrates, be it clear or tinted are being cut-to-size before providing ceramic designs and immediately heat treated before providing magnetron coating on the glass substrates. There are major disadvantages associated with this process, the major one being the need for the glass substrates to be cut-to-size prior to the coating of the substrates. This is because of the inability of cutting the glass substrates after heat treatment. In additional to this:

a) Ceramic based enamel paints when applied on glass substrates are not suitable for transportation, post-processing and subsequent coating in their dried form due to their very low green-strength and adhesion. Green strength is the mechanical strength of the enamel that allows the handling of the material prior to the final processing step.

b) Commonly used water or organic diluent based ceramic enamel have very low binder content and hence show low green-strength and adhesion to the glass substrates. Therefore, immediate heat treatment becomes necessary. Transportation and further handling of the ceramic coated glass substrate before heat treatment removes/degrades the coated layer or patterns.

c) Dried ceramic enamel layers on glass substrates cannot be used for subsequent coating processes. This is because the dried ceramic enamel layer produces powders immobilized on the coated areas which dislodge from the glass substrates in vacuum environment of the sputter coating.

d) Hence subsequent coating is only possible after the heat treatment of the ceramic enamel coated glass substrate. In such a case, cutting glass substrates to specific sizes and immediate heat treatment of such cut-to-size substrates needs to be performed prior to the sputtering process, which reduces the yield of the products.

e) Further, after the sputtering process, if the functional layers need to be heat treated, then heat treating of the glass substrate that is already heat treated possess immense problems and challenges.

Alternatively, a few patterned products are also created by using a magnetron-coated glass as a substrate on which a ceramic enamel is painted and heat treated after drying. However, in such products the color and design of the pattern is affected by the tint of the magnetron coating when viewed from the glass side. Thus there is a need to improve ceramic enamel properties in order to overcome the above listed disadvantages associated with producing patterned glasses. The present disclosure proposes to use a moderate amount of polymer binder in an enamel in order to enhance the green-strength of the enamel by virtue of which the enamel coated glass can be transported and post-processed in their dried/ cured form. Due to the enhanced adhesive and cohesive properties of the enamel, the cured enamel layer can be used for subsequent coating using vacuum-based methods.

The present disclosure overcomes all the previously mentioned drawbacks associated with ceramic enamel coating and the manufacturing of patterned glass substrates by providing an enamel layer (in the form of a pattern) directly on the surface of the glass substrate and subsequently applying a vacuum-based sputter coating over the enamel layer such that the color and design of the enamel layer is not affected by the thin-film coating provided by vacuum-based sputtering. The coated glass product can then be transported, post-processed before being heat treated to obtain a patterned functionally coated glass substrate. The patterned functionally coated glass substrate when viewed from the glass side (i.e. from outside a building incorporating such a patterned functionally coated glass substrate) exhibits the vibrant design and color of the enamel layer and as well provides the performance of the functional coating.

Further the process of making the patterned functionally coated glass substrate of the present disclosure improves the production yield due to its ability to provide enamel coating and functional layer coating subsequently to large jumbo sized glass substrates which can then be cut-to-size and heated both before or after being handled, which includes processes such as washing, grinding, drilling, shaping, toughening etc. Summary of the Disclosure

In one aspect of the present disclosure, a patterned functionally coated glass article is disclosed. The patterned functionally coated glass article comprises of a glass substrate provided with a hybrid coating comprising an enamel layer provided directly over the surface of the glass substrate and a performance coating overlying the enamel layer and the glass substrate. The hybrid coating provides a patterned surface as well imparts solar control, low-emissivity, anti-reflectivity and / reflectivity to the glass substrate. The patterned functionally coated glass article can be handled before heat treatment and have optimized Daylight Glare Probability (DGP).

In another aspect of the present disclosure, a method of making a patterned functionally coated glass article is disclosed. The method comprises the steps of cleaning and drying the surface of a glass substrate, applying an enamel layer on the surface of the glass substrate in any desired pattern, curing the glass substrate at a temperature between 25 °C and 400 °C, cleaning and drying the patterned glass surface, providing a performance coating directly over the enamel layer, handling the patterned multilayer coated glass substrate and heating the patterned coated glass substrate to a temperature above 600 °C.

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 in the accompanying figures.

FIG. 1 illustrates a top and cross-sectional view of a patterned functionally coated glass article, in accordance with one embodiment of the present disclosure;

FIG. 2A illustrate luminance map of high-glare object seen through a comparative glass sample, according to one embodiment of the present disclosure;

FIG. 2B illustrate luminance map of high-glare object seen through the patterned functionally coated glass article of the present disclosure, according to one embodiment of the present disclosure; FIG. 3 illustrates a chart depicting the spectrophotometric analysis of a comparative sample and patterned functionally coated glass articles of the present disclosure, according to one embodiment of the present disclosure; and

FIG. 4 illustrates a flowchart for a method of making a patterned functionally coated glass article, in accordance to one 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 the like parts. Embodiments disclosed herein are related to a patterned functionally coated glass article.

The term "patterned functionally coated glass article" as used herein relates to a glass substrate having a decorative pattern and functionalities such as solar control, low-emissivity, anti-reflectivity and/or reflectivity created by a combination of an enamel layer and a performance coating; and is easy to handle, shape/cut to desired sizes and capable of being transported while retaining the aesthetics and durability before heat treatment and also adapted to undergo a thermal tempering and/or thermal hardening operation and/or other comparable heat treatment process without creating defects (e.g. aesthetical defects in the enamel layer or functional defects in the performance coating).

The term“hybrid coating” as used herein relates to employing wet- coating techniques such as curtain coating, digital printing, roller coating, spray coating, screen printing, gravure coating, ink-jetting or dip coating on the surface of glass substrate and subsequently subjecting the coated glass substrate to one of the coating techniques selected from magnetron sputtering, reactive-magnetron sputtering, pulsed layer deposition, chemical vapor deposition, atomic layer deposition, thermal evaporation or e-beam evaporation.

The term“performance coating” as used herein relates to a single or a multilayer coating for imparting functionalities such as solar control, low-emissivity, reflectivity, anti-reflectivity, easy to clean, antimicrobial or their combinations thereof.

The term“pattern” as used herein refers to any decoration created on the surface of the glass substrate by applying an enamel layer of the present disclosure in any form, size and shape in such a way that the decoration covers at least 5% and not more than 90% of the total surface area of the glass substrate.

FIG. 1 illustrates the top and cross-sectional view of a patterned functionally coated glass article 100 in accordance with one embodiment of the present disclosure. As shown, the patterned functionally coated glass article 100 includes a glass substrate 110. The glass substrate 110 is provided with a hybrid coating 200 on one or both surfaces of the glass substrate 110. The hybrid coating 200 comprises of an enamel layer 201 and a performance coating 202. The enamel layer 201 is provided directly over the surface of the glass substrate 110 and the performance coating 202 is provided over the enamel layer 201 as well as on the adjacent areas of the enamel layer on the surface of the glass substrate 110 not provided with the enamel layer 201.

The glass substrate 110 of the present disclosure is a soda lime or a borosilicate glass. One or more surfaces of the glass substrate 110 is a clear, an extra clear, an acid etched or a sand blasted (on entire surface or in specific design patterns) surface. The glass substrate 110 in accordance to certain example embodiments of the current disclosure is a laminated glass substrate with PVB, EVA or PET, an annealed glass substrate, a heat strengthened glass substrate, or a toughened glass substrate.

The thickness of the glass substrate 110 used herein in accordance to certain example embodiments of the present disclosure is 4 mm and it may further range between 0.5 mm to 19 mm. The coating surface of the glass substrate 101 is prepared by polishing (by rotating brush) with ceria and calcium carbonate or alumina or any other suitable abrasive powders. Optionally the glass substrate 110 is treated with solvents such as acetone or IP A. The glass substrate 110 is then dried thoroughly by compressed air knife.

The coating surface 101 of the glass substrate 110 is further optionally treated with an adhesion promoter such as organsilanes, aminopropyltriethoxysilane, ethylester, propyloxymethylester, butyloxyethyl ester, or acrylate based resins such as acrylic acid.

The enamel layer 201 comprises of polymeric binders, glass frit and inorganic pigments dispersed in an organic diluent and oil. The enamel layer 201 comprises of not more than 40 % of inorganic pigments, not more than 25 % of polymeric binders and not more than 85 % of glass frits. The polymeric binders are selected from the group consisting of esters, acrylic esters, epoxies, polyols, urethanes, silicones, melamine and their combinations thereof. In one embodiment of the present disclosure, the polymeric binder has an onset of decomposition between 290°C - 300°C. The inorganic pigments present in the enamel layer 201 is selected from the group consisting of titanium dioxide, zinc oxide, iron or other metal ion doped titania, copper oxide, chromium oxide, cobalt oxide, lithium niobate, manganates, berilium oxide, cadmium sulfide or cadmium telluride. The glass frit present in the enamel layer 201 can be a zinc based glass frit, a bismuth based glass frit or their combinations thereof. The polymeric binders, inorganic pigments and glass frit were added to a blade mixer and mixed along with organic diluents such as di-acetone alcohol, ether glycol, xylene, acetone, isopropyl alcohol (IPA) or ethyl methyl ketone in order to obtain a desired viscosity and thixotrophy.

In one embodiment, the enamel layer 201 may further optionally contain additives such as viscosity and flow modifying agents or deflocculants or surfactants in trace amounts. Conventional and traditionally used additives can be used for the purpose of this embodiment. In alternate embodiments, an adhesion promoter is added to the enamel layer 201 directly instead of being applied onto the glass. Additives such as thinners, for example, ethylester, propyloxymethylester, butyloxyethyl ester can also be added.

The enamel layer 201 is applied on the glass substrate 110 by screen printing, roller coating, curtain coating, digital printing, gravure coating, dye coating, masking and spray painting or spray coating. The enamel layer covers at least 5% of the total surface area of the glass substrate 110 and the thickness of the enamel layer 201 is no greater than 100 pm. The enamel layer 201 is applied in such a way as to form any decorative pattern or design or shape or picture. With increasing customer interests in incorporating texts, aesthetic designs, advertisement campaigns etc., as add ons on traditional windows/ facades, this embodiment of creating various decorative designs becomes significant.

Various patterns including circular dots with diameters ranging between 1 mm and 6 mm and pitch ranging between 1 mm and 6 mm or rectangular bars having a width of 1 mm to 100 mm and pitch ranging between 1 mm and 60 mm may be provided on the glass substrate 110. The patterns listed above are purely for teachings purposes only and do not in any manner limit the scope of the present disclosure. The scope of the present disclosure includes all design shapes, sizes, patterns, pictures, letters, numbers and all other randomized designs in all gradients created by the enamel composition of the present disclosure.

In one embodiment, screen-printing of the enamel layer 201 over the surface of the glass substrate 110 demands the enamel to have a thixotropic property that causes the enamel to flow under pressure of the screen-printing squeeze and resist flowing once the pressure is put off. In one aspect, the viscosity/ thixotrophy is controlled by dilution. Enamel compositions with very low solvent content show high thixotropy. Hence, a moderate thixotropy (non-Newtonian behavior) can be achieved by controlled dilution of the enamel composition. The change in thixotropy behavior of the enamel compositions at various dilutions was tested before obtaining a referred dilution of 5% - 20%

In one embodiment of the present disclosure, polyester screens of grade 90T were used for screen-printing the enamel composition on the surface of the glass substrate 110. In alternate embodiments, other grades such as TW may also be used to control the thickness and other parameters of screen-printing. In one aspect of the current embodiment, evaporation of the diluents brings about drying and clogging of the screens and thereby hamper the yield and fidelity of the screen-printing process. In order to prevent such evaporation, low-evaporation oil such as linseed oil is added to the enamel composition. In one preferred embodiment, the diluent and oil are used in a ratio of 1 : 1 wt%. The addition of low-evaporating oil slows down the evaporation in isothermal condition and up to temperatures below 350 °C for about an hour.

The enamel layer 201 is cured by air drying, IR, UV or electron beam or laser curing techniques. The temperature of curing ranges between 25°C - 400 °C for IR with resident time between 2.5 minutes and 7 minutes. The UV curing is accomplished with Mercury vapor lamp (H type), Mercury vapor lamp with iron additive (D type), Mercury vapor lamp (V type), Xenon, UV LED’s. The UV curing is initiated by cationic or free radical initiation mechanism. The electron beam curing is achieved by scanning or continuous beam. On curing, the polymeric binders present in the enamel layer 201 provide green strength to the glass substrate 110. This enables the glass substrate 110 to withstand subsequent coating.

A performance coating 202 is provided overlying the enamel layer 201 and on surface areas of glass substrate 110 adjacent to the enamel layer 201 that is not covered by the enamel layer 201. As depicted in FIG. 1, the performance coating 202 covers the entire surface (100%) of the glass substrate 110 including areas of the glass substrate 110 with and without the enamel layer 201. In one embodiment of the present disclosure, the performance coating 202 comprises of at least one functional layer and/or at least one dielectric layer. In multiple embodiments of the present disclosure, the performance coating 202 can be made of a single layer or multiple layers.

The functional layer in multiple embodiments of the present disclosure, can be made of at least one metal or metal alloy selected from the group consisting of Ag, Nb, Ni, Cr, Zr, Mo, Ta, Ti, V, In, Sn, Pb or their oxide or nitrides thereof. The dielectric layer in multiple embodiments of the present disclosure, can be made of at least one oxide or nitride or oxynitride of metals or metal alloys selected from the group consisting of Sn, Nb, Ti, Ta, Zn, Si, Al, Zr, Ni, W or combinations thereof. In one embodiment, the performance coating 202 may comprise of a single functional layer flanked on both sides by dielectric layers. In another embodiment of the present disclosure, the performance coating 202 may comprise of two or more functional layers each flanked on both sides by dielectric layers. In yet another embodiment of the present disclosure, the performance coating 202 may further comprise of additional barriers layers surrounding the functional layers made of materials not limited to ZnO, NiCr or SnZnO. In yet another embodiment, the performance coating consists of a single layer of indium tin oxide (ITO) provided over the enamel layer 201. In still another embodiment, the performance coating consists of one or more functional layers flanked by one or more dielectric layers, wherein the performance coating also includes additional layers above or below the functional layers and/or dielectric layers.

In example embodiments of the present disclosure, the performance coating 202 overlying the enamel layer 201 can have a layer stack as shown below in the order of layers moving away from the glass substrate 110:

Performance coating 202: Si₃N4/ NbN/ S13N4

Performance coating 202: Si₃N4/ NiCr/ Ag/ NiCr/ Si₃N₄/ TiO_x

Performance coating 202: Si3N4/ ZnO / NiCr/ Ag/ NiCr/ ZnO / Si3N4/ SnZnOx/ ZnO/ NiCr/ Ag/ NiCr/ ZnO / Si3N4/ TiZrOx

The performance coating 202 is provided by coating techniques selected from the group consisting of magnetron sputtering, reactive-magnetron sputtering, pulsed layer deposition, chemical vapor deposition, atomic layer deposition, thermal evaporation or e-beam evaporation. The thickness of the performance coating 202 ranges between 20 nm and 300 nm. The performance coating 202 provides various functionalities to the glass substrate depending on the materials present in the functional layers, dielectric layers, barrier layers and / or additional layers. The functionalities obtained by the glass substrate 110 include but not limited to solar control, low-emissivity, anti-reflectivity, reflectivity or their combinations thereof.

The performance coating 202 illustrated above in accordance with certain example embodiments of the current disclosure are provided to assist in understanding the teachings disclosed herein and should not be interpreted as a limitation to the scope or applicability of the teachings. However, other performance coating 202 may certainly be implemented using the various embodiment of this disclosure.

The patterned functionally coated glass article 100 can be handled and transported both before and after heat treatment without damaging the hybrid coating 200. For instance, the patterned functionally coated glass article 100 may be cut, ground, have holes drilled therein, etc., without causing the enamel layer 201 and the performance coating 202 to peel off or to become damaged at the borders of the cutting line and drilling hole edges, both before and after heat treatment. The enamel layer 201 and the performance coating 202 do not peel off or degrade during edge grinding, polishing, storage, transportation, etc.

The patterned functionally coated glass article 100 both before and after being handled can be subjected to heat treatment at high temperatures greater than about 600 °C for a period ranging between 2 minutes and 20 minutes, preferably for a maximum period of 10 minutes, depending, inter alia, on the type of oven and on the thickness of the glass substrate 110.

The patterned functionally coated glass article 100 of the present disclosure combines aesthetics effect of a patterned glass and performance functionalities of a functionally coated glass with increased yield of production. In one other embodiment of the present disclosure, the patterned functionally coated glass article 100 achieves reduced luminous intensity of the glare source at eye level without significantly affecting the view when incorporated as a monolithic glazing or a double glazing unit in a building with the coating stack 200 facing inside the building. In one aspect of the embodiment, positioning of the dot pattern strategically aid in reduction of the luminous intensity.

In yet another embodiment of the present disclosure, shading can also be achieved with the use of the patterned functionally coated glass article 100 of the present disclosure in building applications. The degree of shading caused by the patterned functionally coated glass article 100 of the present disclosure can be controlled by controlling the shape, size, thickness, coverage, distribution, opacity and color of the pattern or design obtained by the enamel layer 201 applied directly over the surface of the glass substrate 110. In example embodiments, small size dots with high pitch can generate glare reduction but without considerable shading perception. In another example embodiment, a thicker enamel layer 201 (with high effective opaqueness) will produce greater shading perception in comparison to thinner enamel layer 201 of equivalent designs.

In yet another embodiment, the patterned functionally coated glass article 100 can be used in construction of anti-collision facades or bird-friendly facades. Providing the enamel layer 201 of the coating stack 200 in a specific shape, pattern and color can prevent birds from perceiving glazing as a see-through impression for clear flight path. The occurrence of bird collision can significantly be reduced from a threat factor of 100 (for clear glass) to about 10 for the patterned functionally coated glass article 100 of the present disclosure having an enamel layer covering only about 6.25 % of the surface area of the glass substrate 110, as recommended by American Bird Conservancy (https : //abcbirds .org) .

Examples Example 1

Enamel Coated Glass Substrate

The glass substrate coated with the enamel composition of the present disclosure was tested for adhesion, abrasion and other thermos-mechanical properties. The enamel applied over the surface of the glass substrate consisted of titania as the pigment and exhibited a white colour design on the glass surface. The dry thickness of the enamel layer after being coated and cured was measured to be 17 microns with an instrumental deviation of +/- 2.5 microns.

Cross-Hatch Test

The adhesion of the enamel layer on glass substrates was measured by cross-hatch (ASTM standard D 3359-00, 6 teeth, 2mm, with brushing and with adhesive tape peel). The adhesion value ranged between 3 and 4.

Taber Abrasion test

Taber abrasion test was used for performing accelerated wear resistance testing. It involved mounting a flat enamel coated glass 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 gram of pressure against the specimen, exclusive of the weight of the wheel in contact with sample. The weight before and after the test was measured to calculate the overall weight loss of the test sample. The loss in weight was measured to be 0.05% after 1000 cycles.

Example 2

Patterned Functionally Coated Glass Substrate

The glass substrate from example 1 was subsequently coated with the below performance coating by magnetron-sputtering:

Layer stack 1 : S13N4/ NbN/ S13N4

Layer stack 2: S1₃N₄/ NiCr/ Ag/ NiCr/ S1₃N₄/ TiO_x Layer stack 3: S13N4/ ZnO/ NiCr/ Ag / NiCr/ ZnO/ S13N4/ SnZnOx/ ZnO/

NiCr/ Ag/ NiCr/ ZnO / S13N4/ TiZrO_x

Adhesive Tape Peel Test

The adhesion property of the glass substrates provided with the enamel and the layer stacks 1 , 2 or 3 was tested by the tape test. The tape test was performed on glass samples provided with the enamel layer and the layer stacks 1 , 2 or 3 that were cured and on glass samples that were subsequently heat treated post the curing process. Standard Test Methods for Rating Adhesion by Tape Test - ASTM D3359, EN ISO 2409 was followed to evaluate the glass samples. All the glass samples tested were found to pass the tape test without leaving any major on the tape.

Comparative Example 1

Glare Reduction

The patterned functionally coated glass article of the present invention was found to have applications in glare reduction. Glare reduction of a glass sample 1 coated with an enamel layer and a performance coating (S13N4/ Nb/ S13N4) according to one embodiment of the present disclosure was compared with that achieved by a glass sample 1 provided with only the performance coating (SEN4/ Nb/ S13N4) with high dynamic range (HDR) image analysis. Sample 1 comprises of an enamel layer covering 20% of the surface area of glass with circular dots of 3.2 mm. Sample 2 does not comprise of any enamel layer.

A digital camera (CMOS sensor of size 22.3 x 14.9 mm with effective 24.2 megapixels, and image resolution 6000 X 4000) with a fish-eye lens was targeted towards a high-glare zone coming from an east-facing facade of a building from its interior. The glass samples mentioned above were placed intervening the line-of-sight of the camera and the high-glare zone. In order to ensure the capture of the entire light in the view of the camera, images were taken with a fixed camera aperture setting of F9.0 and varying shutter speeds between 2 seconds and 1/8000 seconds. The images were then assembled (stitched) using Photo Sphere software. FIG. 2A and FIG. 2B illustrates the luminance maps of the high-glare range object seen through sample 2 and sample 1, respectively. The luminance comparison made between sample 1 and sample 2 is shown in Table 2.

Table 2:

The glare reduction achieved by the glass samples 1 and 2 was elucidated from the images analysis depicted above using the procedure for Daylight Glare Probability (DGP) calculation found in the literature (Van Den Wymelenberg, K., Inanici, M., Johnson, Pr., 2010, The effect of luminance distribution patterns on occupant preference in a daylit office environment. Leukos 7(2): 103-122). The results are shown in Table 3.

Table 3: Glare Reduction

From Table 3, it was found that with 6.25% of the glass facade surface area being covered by sample 1 results in 9.48% reduction in DGP compared to the same coverage of the glass facade by sample 2.

Comparative Example 2

Effect of Thickness on % Transmittance

The effect of thickness of the enamel layer of the patterned functionally coated glass substrate of the present disclosure on the level of light transmittance was determined by spectrophotometric analysis using a Perkin Lambda 1050 for the entire solar spectrum range. 2 glass samples of 4 mm ultra-clear glass substrate were taken and provide with an enamel layer (enamel paint containing titania) covering 100% of its surface area. A third glass sample prepared according to the present disclosure containing subsequent coating of enamel and performance coatings was also studied. The enamel layer thickness of a thin sample 1 was measured to be 15-20 pm while that of a thick sample 2 was measured to be 30-35 pm. The result of the spectrophotometric analysis is depicted in FIG. 3.

The below conclusions were arrived upon from the graph depicted in

FIG. 3:

The transmission in the visible range and the IR range of the solar spectrum can be regulated by changing the thickness of the enamel layer.

The shading coefficient was found to be 0.367 and 0.284 for enamel layer thickness 15-20 pm and 30-35 pm respectively, with 100% coverage.

Absorption (or reduction in transmittance) in the visible and IR range can be achieved by incorporating specific absorbing ceramic particles in the enamel paint. For example, ceramic particle including but not limited to, Ti02, ZnO, Sn02, BeO etc. can be used.

Addition of performance coating, as elucidated in example 2 with solar factor 0.363, shading coefficient of 0.418, and U value of 3.631 W/m²-K can reduce the % transmission considerably, especially in the IR region. Thus an optimized selection of enamel layer and performance coating for the making of patterned functionally coated glass article of the present disclosure can modify the light transmission and heat control achieved by the facades and windows incorporating such patterned functionally coated glass articles.

Comparative Example 3

The solar factor and light transmission of the patterned functionally coated glass article of the present disclosure was measured and compared with that of a coated glass product from Saint-Gobain Glass having only a performance coating according to the teachings of the present disclosure. The results are tabulated in Table 4.

Table 4: Solar Factor and Light Transmission Values

A reduction in the solar factor and light transmission values can be seen to be exhibited by the patterned functionally coated glass article of the present invention. This demonstrates that the hybrid coating (enamel coating together with the performance coating) present in the patterned functionally coated glass article of the present disclosure synergistically contribute to the reduction of solar factor and light transmission values in comparison with the coated glass product from Saint-Gobain Glass having only the performance coating. Industrial Application

The patterned functionally coated glass article of the present disclosure obtained by a hybrid coating technology viz., a combination of a wet-coating technology and a sputtering technology can find application in both interior and exterior applications. Such interior and exterior applications include facades, windows, doors, partitions, decorative glazing, spandrel, wall cladding, curtain walling, table furniture, kitchen splash backs, tiles etc. Further the patterned functionally coated glass article of the present disclosure can have automotive applications such as quarter lite etc. Installation of the patterned functionally coated glass article of the present disclosure in such applications achieve both aesthetic appeal and functional performance. The utilization of the enamel composition of the present disclosure in the construction facilitates robustness against handling and storage degradation, and enhances flexibility for transportation in the as-coated state.

Further, on heat treatment, the glass article provides safety and functionality without any compromise on the aesthetics of the patterned image. Furthermore, because the enamel layer is applied directly on the glass substrate, the color and design of the pattern created by such an enamel application remains unaffected by the performance coating provided subsequently. The application of the performance coating determines the transmission of optical, UV and IR spectrum of light. The opacity and coverage of the enamel layer synergistically determines the solar factor of the facade, window etc. Thereby the facade or the window exhibits functional performances not limiting to solar control, low-emissivity, reflectivity, anti-reflection, glare reduction, shading and anti-collisions.

The compatibility of the glass substrate to post-processing steps including but not limited to cutting, edge grinding, beveling, drilling, sizing, finishing and transporting after the application of the enamel layer improves the production yield of these glass articles and enables the coating to be performed at the manufacturing site and the post-processing steps listed above at a different location outside the manufacturing facility. The patterned functionally coated glass substrate exhibits good durability performance without compromising its functional and aesthetic performance. The present disclosure also relates to a method 300 of making the patterned functionally coated glass article. The steps involved in making the patterned functionally coated glass article is depicted in FIG. 4 according to one embodiment of the present disclosure. The method 300 comprises of steps 310 to 370. In multiple embodiments of the present disclosure, the patterned functionally coated glass article 100 illustrated in FIG. 1 may be obtained by performing all or selected steps of the method 300 in the same or an altered order depicted in FIG. 4.

In step 310, the glass substrate is first cleaned thoroughly by a mixture of ceria and calcium carbonate powders with the help of rotating brush. The air side of the glass substrate was cleaned. Following which, the cleaned glass substrate was dried thoroughly by compressed air flow knife. In step 320, desired viscosity and thixotropy of the enamel composition was obtained by adding appropriate diluents such as di acetone alcohol and other low-evaporating diluents in a blade mixture. The enamel composition was then applied on the surface of the glass substrate by simple screen printing technique in a continuous process. In one embodiment, the squeeze speed was maintained at 200 - 600 mm/sec. In a specific embodiment, the squeeze speed was maintained at 400 mm/sec.

Various patterns including dots, rectangular bars etc. of varying diameters and depths were created on the surface of the glass substrate. The thickness of the enamel layer was controlled to be not more than 100 pm by using different screens and moderating the screen parameters. In one embodiment, the screen printing was carried out in s controlled environment with the temperature maintained at 19 - 22 °C. The surface area to be covered by the enamel composition of the present disclosure is varied based on the requirement. In one embodiment, the enamel layer is screen printed to cover a surface area ranging between 10% and 80%. In step 330, the enamel coated glass substrate was cured. The enamel coated glass substrate was passed through a continuous convective IR oven with temperatures ranging between 175 °C and 215 °C. Residence time in the oven was between 2.5 minutes to 7 minutes. In alternate embodiments of the present disclosure, other drying techniques including thermal dryers, heat combustion can also be used.

Following enamel coating and drying, the polymeric binders present in the enamel composition of the present disclosure thermally cured and binds with the glass substrate to provide green strength to the glass substrate. As a result, the enamel coated glass substrate can withstand subsequent transportation, washing (if needed), vacuum conditions during sputter-coating. The presence of polymeric binder imparts green strength and its moderate content causes only a low level of outgassing in the vacuum chamber with vacuum level ranging between 10 ⁵ to 10 ⁶ mTorr and working pressure of 1.5 to 1.6 mTorr. Owing to which the sputtering process of the enamel coated glass substrate could be done without much interferences and modifications.

In step 340, the cured enamel coated glass substrate is cleaned with alumina-based abrasive particles using rotating brush. Owing to the good adhesion property and high green- strength of the enamel coated glass substrate, processes such a cleaning and drying do not erode/ affect the patterns created by the enamel layer. In one embodiment, the enamel coated glass substrate is cleaned with de-ionized water and dried under vigorous compressed hot airflow knife at a temperature of about 40 °C. In step 350, the cleaned and dried enamel coated glass substrate is subsequently coated with a magnetron back-layer for imparting functionalities including but not limited to solar control, low-emissivity, reflectivity, anti -reflectivity or their combination thereof.

In one embodiment of the present disclosure, the enamel coated glass substrate is introduced into a vacuum chamber for depositing single or multiple layers of coating using magnetron sputtering or reactive-magnetron sputtering. The performance coating covers the entire surface area of the glass substrate including the surface areas of the glass substrate that is not coated with the enamel. The thickness of the performance coating ranges between 20 nm and 300 nm. In one embodiment, the performance coating comprises of one or more functional layer and/or two or more dielectric layers. In one other embodiment, the performance coating comprises of two or more functional layers and three or more dielectric layers.

In the penultimate step 360, the patterned functionally coated glass substrate can be handled, transported and cut to desired sizes and edge grinded. In one embodiment of the present disclosure, the patterned functionally coated glass substrate can be installed in windows and facades after being handled without the need of any heat treatment. In the final step of 370, the patterned functionally coated glass substrate is heat treated to a temperature ranging between 650 °C and 750 °C for about 3 minutes to 10 minutes. The duration of the heat treatment depends on the glass substrate, the thickness of the glass substrate, surface area covered by the enamel layer, the type of multilayer coatings applied on the glass substrate and its thickness.

During the heat treatment of the patterned functionally coated glass substrate, the polymeric binder present in the enamel composition burns off while the glass frit coalesces through the formation of a liquid phase and forms a permanent film on the surface of the glass substrate. Unlike the organic binders, the inorganic pigments present in the enamel composition do not get burnt off. In one aspect, the polymeric binder is required to have a low char value in order to reduce any blackness imparted during the burning of the polymeric binder during heat treatment. In one embodiment, butyl-poly-methacrylate is used as the polymeric binder either in combination with or without isocyanate as the 2^nd component cross-linker.

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. Fist of Elements

TITLE: A Patterned Functionally Coated Glass Article

100 Patterned Functionally Coated Glass Article

101 Coating Surface

110 Glass substrate

200 Hybrid Coating

201 Enamel layer

202 Performance Coating

300 Method

310 Step

320 Step

330 Step

340 Step

350 Step

360 Step

370 Step

Claims

We Claim:

1) A patterned functionally coated glass article comprising:

a glass substrate provided with a hybrid coating comprising:

an enamel layer provided directly over the surface of the glass substrate in the form of a pattern; and

a performance coating overlying the enamel layer and the glass substrate, wherein the hybrid coating imparts performance properties including solar control, low-emissivity, anti-reflectivity and/or reflectivity to the glass substrate and wherein the patterned functionally coated glass article has optimized Daylight Glare Probability (DGP) and can be handled before heat treatment.

2) The patterned functionally coated glass article as claimed in claim 1 wherein the enamel layer comprises 10 - 25 wt.% of polymeric binders upon curing, glass frit and inorganic pigments dispersed in an organic diluents and oil.

3) The patterned functionally coated glass article as claimed in claim 2 wherein the enamel layer optionally comprises one or more additives selected from the group consisting of viscosity modifying agents, flow modifying agents, adhesion promoters, deflocculants, surfactants or ceramic particles.

4) The patterned functionally coated glass article as claimed in claim 2 wherein the polymeric binder is selected from the group consisting of thermally stable esters, acrylic esters, epoxies, polyols, urethanes, silicones, melamine and their combinations thereof. 5) The patterned functionally coated glass article as claimed in claim 2 wherein the glass frit is zinc -based or bismuth-based glass frit or their combinations thereof.

6) The patterned functionally coated glass article as claimed in claim 2 wherein the inorganic pigment is selected from the group consisting of titanium dioxide, zinc oxide, iron or other metal ion doped titania, copper oxide, chromium oxide, cobalt oxide, lithium niobate, manganates, berilium oxide, cadmium sulfide or cadmium telluride.

7) The patterned functionally coated glass article as claimed in claim 2 wherein the organic diluent is selected form the group consisting of di-acetone alcohol, ether glycol, xylene, acetone, isopropyl alcohol, ethyl methyl ketone or their combinations thereof.

8) The patterned functionally coated glass article as claimed in claim 1 wherein the enamel layer covers more than 5% and less than 90% of the total surface area of the glass substrate.

9) The patterned functionally coated glass article as claimed in claim 1 wherein the performance coating covers the entire surface area of the glass substrate.

10) The patterned functionally coated glass article as claimed in claim 1 wherein the performance coating includes at least one functional layer and/ or at least one dielectric layer.

11) The patterned functionally coated glass article as claimed in claim 10 wherein the functional layer comprises of at least one metal or metal alloy selected from the group consisting of Ag, Nb, Ni, Cr, Zr, Mo, Ta, Ti, V, In, Sn, Pb or their oxides or nitrides thereof. 12) The patterned functionally coated glass article as claimed in claim 10 wherein the dielectric layer comprises of at least one oxide or nitride or oxynitride of metals or metal alloys selected from the group consisting of Sn, Ti, Ta, Zn, Si, Al, Zr, Ni, W or their combinations thereof.

13) The patterned functionally coated glass article as claimed in claim 1 can be heat treated to a temperature above 600 °C after handling to obtain a heat-treated patterned functionally coated glass article.

14) The patterned functionally coated glass article as claimed in claim 1 or claim 13 wherein handling includes cutting, edge grinding, beveling, drilling, sizing, finishing and transporting of the patterned functionally coated glass article.

15) An anti-collision glazing configured as a monolithic or a double glazing or a laminated glazing incorporating the patterned functionally coated glass article as claimed in claim 1, the hybrid coating on face 2 or face 3, the faces of substrates being numbered from outside to the inside of the building or room which is equipped therewith.

16) The anti-collision glazing as claimed in claim 16 exhibits reduced luminous intensity at glare source at eye level.

17) A method of making a patterned functionally coated glass article as claimed in claim 1 comprising the steps of:

cleaning and drying the surface of a glass substrate;

applying an enamel layer on the surface of the glass substrate in any desired pattern;

curing the glass substrate at a temperature between 120 °C and 230 °C; cleaning and drying the patterned glass surface; providing performance coating directly over the enamel layer and the glass substrate;

handling the patterned multilayer coated glass substrate; and heating the patterned coated glass substrate to a temperature above 600

°C.

18) The method as claimed in claim 17, wherein the enamel layer is provided by coating techniques selected from the group consisting of screen printing, embossed roller coating, digital printing, curtain coating, gravure coating, ink-jetting, spray painting or dip coating.

19) The method as claimed in claim 17, wherein the thickness of the enamel layer is not more than 100 pm.

20) The method as claimed in claim 17, wherein the performance coating is provided by coating techniques selected from the group consisting of magnetron sputtering, reactive-magnetron sputtering, pulsed layer deposition, chemical vapor deposition, atomic layer deposition, thermal evaporation or e-beam evaporation.

21) The method as claimed in claim 17, wherein the thickness of the performance coating ranges between 20 nm and 300 nm.