Field of the invention

The invention relates to an insulating glazing unit suitable for different interior and exterior applications such as windows, doors, partition walls, curtain walls, roofs. It can also be used in a temperature conditioned product presentation appliance such as a refrigerated cabinet. More particularly, it relates to an insulating glazing unit (IGU) comprising at least a first and second glass pane and an insulating gas that is filling the interspace between the first and the second glass panes.

Description of prior art

Gas-filled insulating glazing units comprising at least two glass panes are widely used for windows, doors, curtain wall, roof. Generally, a first glass pane is placed opposite to a second glass pane and an edge spacer assembly is sealingly coupling the first and the second glass pane around their respective perimeter. The edge spacer assembly typically comprises a spacer element that may be made out of for instance metal or a composite material for spacing the two glass panes a distance from each other. The edge spacer assembly further comprises one or more sealing elements coupled to the spacer element and the glass panes. In this way, a hermetically sealed interspace is formed between the first and the second glass pane that is filled with the insulating gas so as to reduce heat conductivity. The insulating gas is generally air or an inert gas such as argon, krypton, xenon or mixtures of those gases. The spacing between the glass panes may vary between 6 and 32 mm. Such a gas-filled IGU with an edge spacer assembly is for example disclosed by Buddenberg et al in Glass Struct. Eng. (2016) pages 301-313.

However, the insulating glazing units suffer from the glass panes movement or deformation induced by climatological circumstances such as snow, wind, temperature and pressure variations, shocks, or openings/closings in the case of doors and windows. A known problem with IGU's is the so-called climatic load which is acting on the glass panes due to changes in the surrounding climatic conditions such as night and day or seasonable temperature variations between winter and summer. During the production process of IGU's, under given factory temperature and pressure conditions, the interspace is filled with the insulating gas and the interspace is further kept hermetically sealed. If the gas temperature or the atmospheric pressure changes, a pressure difference between the interspace and the environment occurs. The pressure balance can be restored by an increase or decrease of the volume in the interspace. The expanding or contracting gas volume of the interspace causes deformation of the glass panes, which in turn results in mechanical stress. The deformations resulting from these climatic loads are discussed for example by Buddenberg et al in the reference mentioned above.

In addition to these long term stresses caused by the climatic loads, the glass panes also suffer from short term mechanical stresses. These short term mechanical stresses are caused for example by blowing wind, shocks or openings/closings of a door or window, which result in a pressure and depression exercised on the IGU. As a result for instance of wind pressure, the glass panes of the IGU will bend. Depending on the bending level, cracks and/or breakage might occur in the glass panes. The bending can also disturb the vision through the glazing units. This effect of bending glass panes is increased when the size of the panes is larger, for example when using large windows for commercial buildings.

A known solution to mitigate these problems is to increase the thickness of the glass panes. This however results in an increased weight of the insulating glazing unit. Another solution is to segment the glass panes in smaller elements. A further known solution is to reinforce the exterior glass pane of the glazing unit by attaching a wind brace.

It is an objective of the present invention to provide an improved gas-filled IGU that overcomes some or all the aforementioned drawbacks. It is therefore an object of the invention to provide a gas-filled IGU having an improved resistance to short term mechanical stresses such as wind load, while still being able to withstand the long term climatic loads such as night and day temperature variations. It is a further objective to provide gas-filled IGU's having glass panes with larger surfaces or else smaller thickness while keeping the glass panes deformation within allowable limits. Summary of the invention

The present invention is defined in the appended independent claims. Preferred embodiments are defined in the dependent claims.

According to an aspect of the invention, a gas-filled insulating glazing unit (IGU) is provided. Such a gas-filled IGU comprises at least a first and a second glass pane, an edge spacer assembly configured for sealingly coupling the first and the second glass panes so as to form a hermetically sealed interspace between the first and the second glass pane and an insulating gas filling the interspace.

The gas-filled IGU according to the invention comprises one or more coupling members disposed in the interspace for coupling the first glass pane with the second glass pane. Each of the one or more coupling members comprises a plurality of piled and adhesively interconnected parts, wherein at least a first part for stiffening the coupling member comprises a rigid material having a Young's modulus equal or larger than 0.5 GPa, and wherein at least a second part for releasing stress resulting from climatic loads comprises a viscoelastic polymer having a Young's modulus lower than 0.5 GPa. A top surface and a bottom surface of the plurality of piled and adhesively interconnected parts are attached to respectively the first and the second glass pane. Hence, the top surface and bottom surface of the plurality of the piled and adhesively interconnected parts are respectively forming the top and bottom surfaces of the coupling member. Advantageously, with the one or more coupling members, the gas-filled IGU according to the invention is stiffer, having an improved resistance to the above discussed short term mechanical stresses, e.g. caused by wind, and at the same time, the IGU's according to the invention can still withstand the climatic loads also called long term stresses, which are also discussed above.

Indeed, by piling up and adhesively interconnecting a number of parts and attaching the top and bottom surfaces of the piled parts to the glass panes, a coupling member is formed that is materially coupling the two glass panes, which allows for a transfer of loads from one glass pane to the other glass pane.

As a result of the improved interconnection between the glass panes, the two glass panes will behave as a single thicker glass pane and hence better resist to a bending caused by a pressure to the glass panes. In addition, by providing a coupling member with at least two parts, one stiffening part comprising a rigid material and another part comprising a viscoelastic polymer, the glass panes will still be able to expand with respect to each other when there is a temperature gradient due to the fact that the viscoelastic material can deform and hence release stress from the glass panes. Hence, the IGU's according to the invention will not only have an improved resistance to the short term stresses, but also still respond, generally slowly, to the long term cyclic climatic loads resulting from for example night and day or seasonable temperature differences.

Advantageously, with the coupling members according to the invention the glass panes can have large surfaces, surfaces that are much larger when compared to classical IGU's not having the coupling members as claimed or can have a reduced thickness.

As mentioned above, the rigid material of the at least first part for stiffening the coupling member has a Young's modulus equal or larger than 0.5 GPa, preferably this Young's modulus is equal or larger than 0.8 GPa and more preferably equal or larger than 1.0 GPa. In preferred embodiments, the rigid material of the at least first part has a density equal or larger than 0.5 g/cm ³ , preferably equal or larger than 0.8 g/cm ³ and more preferably equal or larger than 1.0 g/cm ³ . The viscoelastic polymer of the at least second part for releasing stress resulting from climatic loads has a Young's modulus lower than 0.5 GPa.

In embodiments according to the invention, the viscoelastic polymer of the at least second part has a loss coefficient of at least 0.1, preferably at least 0.3, more preferably at least 0.5.

In preferred embodiments, the one or more coupling members are transparent.

According to another aspect of the invention, the IGU's of the invention are used in a glazed assembly for use in exterior or interior applications such as for instance a window, a door, a partition wall, a curtain wall, a roof or the like. They are for instance advantageous for modern or commercial buildings requiring large glazed surfaces. The IGU's according to the invention can be used in framed glazed assemblies, or in frameless glazed assemblies. They can also be used in a temperature conditioned product presentation appliance such as a refrigerated cabinet.

According to still a further aspect of the invention, a glazed assembly is provided comprising a gas-filled insulating glazing unit according to the invention and a wind brace fastened to the gas-filled insulating glazing unit for reducing a deflection resulting from a wind pressure. In this assembly, the wind brace is fastened to the glass pane that is in contact with the interior atmosphere of a building at a location where one of said one or more coupling members is coupling the first glass pane with the second glass pane.

Advantageously, the IGU's according to the invention allow more flexibility than classical IGU's to use and locate the wind braces. In contrast, the wind braces in classical IGU's must be fastened to the glass panes at the level of the edge spacers, i.e. at the sides of the panes. With the classical IGU's, the wind braces must also be fastened to the exterior glass pane which can result in thermal bridges through the part linking the glass pane to the wind brace. Short description of the drawings

These and further aspects of the invention will be explained in further detail by way of example and with reference to the accompanying drawings in which:

Fig.l shows a front view of a gas-filled IGU according to the invention; Fig.2 shows a cross sectional view of an embodiment of a gas-filled IGU according to the invention;

Fig.3 shows a cross sectional view of an edge spacer assembly;

Fig.4 shows a cross sectional view of a further embodiment of a gas-filled IGU

according to the invention; Fig.5 shows an example of an IGU according to the invention comprising two coupling members;

Fig.6 shows an example of an IGU according to the invention comprising multiple coupling members;

Fig.7a shows a perspective view of an exemplary embodiment of a coupling member comprising a stiffening part and a viscoelastic part;

Fig.7b shows a perspective view of an exemplary embodiment of a coupling member comprising two stiffening parts;

Fig.7c shows a perspective view of an exemplary embodiment of a coupling member comprising two viscoelastic parts; Fig.8a shows a cross sectional view of a coupling member according to the invention comprising a stiffening part and a viscoelastic part;

Fig.8b shows a cross sectional view of a coupling member according to the invention comprising two stiffening parts; Fig.8c shows a cross sectional view of a coupling member according to the invention comprising two viscoelastic parts;

Fig.9a shows a perspective view of an example of a coupling member having the shape of a parallelepiped and having two viscoelastic parts and one stiffening part; Fig.9b shows a further perspective view of a coupling member having the shape of a parallelepiped and having a viscoelastic part and a stiffening part;

Fig.9c shows a further perspective view of an example of a coupling member according to the invention;

Fig.10a shows a cross sectional view of an example of a glazed assembly comprising a wind brace,

Fig. 10b shows a cross sectional view of a further example of a glazed assembly

comprising a wind brace,

The figures are not drawn to scale. Generally, identical components are denoted by the same reference numerals in the figures. Detailed description

The gas-filled insulating glazing units (IGU) according to the invention are typically used for interior and exterior applications such as windows, doors, partition walls, curtain walls, roofs and the like. It can also be used in a temperature conditioned product presentation appliance such as a refrigerated cabinet. The invention is not limited to the number of glass panes the IGU comprises, typically the IGU's comprise two glass panes, commonly known as double glazing or three glass panes, commonly known as triple glazing. An illustrative example of a double glazing gas-filled IGU according to the invention is shown on Fig. 1, Fig. 2 and Fig. 4 to Fig. 6. The IGU's according to the invention are not limited to any specific glass panes. For instance, the glass panes can have a square, a rectangular, a circular, a triangular shape or any other shape, they may be flat or curved. The glass panes of the IGU's are not limited to any specific thickness and the different glass panes of the IGU's can have the same or different thicknesses, respectively known as symmetric and asymmetric IGU's. The thickness may typically vary from 0.5 mm to 25 mm. Similarly, the glass panes of the IGU's can have the same or different sizes like in stepped IGU's. The type of glass panes is not particularly limited and maybe float glass panes or alternatively cast or drawn glass panes.

The glass panes according to the invention are made of glass whose matrix composition may belong to different categories. The glass may be a soda-lime-silicate glass, an alumino-silicate glass, an alkali-free glass, a boro-silicate glass and the like. It may be a clear, extra-clear/low-iron or colored glass sheet. Preferably, the glass panes of the invention are made of a soda-lime glass or an alumino-silicate glass. Non-limiting examples of glass panes are Planibel ^® Clear, Linea Azzura ^® , Dragontrail ^® , Tirex ^® , Falcon ^® , Clearvision ^® , Clearlite ^® .

The glass panes can be chosen among all glass technologies, among them: float clear, extra-clear or colored glass, (partially) acid etched or (partially) sand blasted glass and combinations thereof.

The glass panes can be at least partially coated. By partially coated is meant that at least a part of their surface can be coated with a low-emissivity or a solar control coating or enamelled or combinations thereof. Thermally treated or chemically tempered glass panes can be used. The thermally treated glass pane can be treated by any thermal treatment known by the skilled person such as heat strengthening (according to EN 1863-1:2011), thermal toughening (according to EN 12150-2:2015) or thermal toughening and heat soaking (according to EN 14179-2:2005). The glass pane thermally treated according to these standards is suitable as safety glass. Chemical tempering is particularly suited for thin glass panes.

Laminated glass panes may also be used, they consist of two or more glass panes assembled by a polymeric film, such as polyvinylbutyral (PVB), ethylenevinylacetate (EVA), thermoplastic polyurethanes (TPU) or ionoplast interlayer such as SentryGlas ^® . In case of breakage, glass pieces remain attached to the polymeric film, avoiding people injuries, and maintaining the separation active.

The IGU's according to the invention are more robust to withstand short term stress, such as resulting from wind, shocks or openings/closings in the case of doors and windows, and at the same time still withstand the long term stress such as resulting from climatic loads, as defined and discussed here above in the prior art section.

A gas-filled insulating glazing unit according to the invention comprises at least a first glass pane, a second glass pane and an edge spacer assembly configured for sealingly coupling the first and the second glass pane, so as to form a hermetically sealed interspace between the first and the second glass pane. An insulating gas, is filling this interspace. Such a gas is generally chosen amongst air, argon, xenon, krypton, or any of their mixtures. Typically, the gas pressure in the IGU interspace is close to atmospheric pressure and may range between 850 and 1030 hPa. The distance between the glass panes in an IGU is generally at least 4 mm and more typically at least 6 mm, it does generally not exceed 32 mm. This distance will namely depend on the type of insulating gas filling the interspace.

The edge spacer assembly typically comprises an edge spacer element and one or more sealant elements. For example, as illustrated in Fig. 3, a first sealant 5b, typically made of polyisobutene is placed between the glass panes and the edge spacer element 5a to hermetically seal the interspace. A second sealant 5c, for example made of silicone or polysulfide is further coupled to the edge spacer element and the first sealant to provide a more overall robust sealing.

The gas-filled IGU according to the invention is characterized in that the IGU comprises one or more coupling members disposed in the interspace for making a coupling between the first and the second glass pane.

This coupling of the first and second glass pane by the one or more coupling members has to be understood as a coupling that, as discussed above, allows the IGU's according to the invention to better withstand the short term stresses and, at the same time, still withstand the long term cyclic climatic loads.

In other words, the coupling member is an element that is configured for coupling the first glass pane with the second glass pane such that when for example a pressure, e.g. due to a wind, is exercised on the first glass pane, the second glass pane will, due to the coupling with the coupling member, help to resist to the force and, as a result, reduce the bending of the first glass pane. Hence, the coupling member together with the second glass pane can act as a strut for the first glass pane. The coupling with the coupling member is also important for the pulling effect when for example the wind drops, the two glass panes will again, due to the coupling, act together as a single pane in response to the pulling. In other words, the two glass panes will behave as a single thicker glass pane. It has to be distinguished from the edge spacer assembly effect. The edge spacer assembly is configured mainly for sealingly coupling the glass panes so as to ensure the tightness (water vapor and insulating gas) of the interspace. Furthermore, the location of the edge spacer assembly at the periphery of the glazing unit does not provide an improved resistance against the short term stresses and long term cyclic climatic loads to the other parts of the glazing. It is particularly the case for IGU's comprising large size and/or thin glass panes.

The IGU according to the invention is further characterized in that each of the one or more coupling members comprises a plurality of piled and adhesively interconnected parts. In some embodiments, said piled parts have a contact surface with the neighbouring part(s) that is substantially parallel to the glass panes. Adhesively interconnected parts have to be understood as parts that are adhered to each other by any adhesive mean, for example with a glue or a double sided adhesive. A top surface Si, and a bottom surface S ₂ i of the plurality of piled and adhesively interconnected parts are attached to respectively the first and the second glass pane. Indeed, by piling a plurality of parts, a top and bottom surface is naturally formed, the top surface being the outer surface of a top part and the bottom surface being the outer surface of a bottom part. In other words, the top and bottom surfaces are surfaces that are not adhesively connected to a neighbouring part, but that are attached to the glass panes. In this way, the parts are not only adhesively interconnected between them, but the outer parts are also attached to the glass panes to form the coupling between the first and second glass pane. The top surface Si, and the bottom surface S ₂ , of the plurality of the piled and adhesively interconnected pa rts correspond to the top and bottom surfaces of the coupling member. The attachment of the top and bottom surfaces to the first and second glass pa ne ca n be made by various attachment means such as anyone of the above adhesive means. Alternative attachment means can be soldering, welding. Another alternative is to directly cure a crosslinkable resin on the glass pa ne. Yet another alternative is to apply a melted material on the glass pane and cool it to the solid state. I n these two last cases, the attachment mean to the glass pa ne and the stiffening or viscoelastic part attached to the glass pane are one single element.

I n some embodiments, as will be further discussed below, some of the parts ca n have an intrinsic adhesive property and will adhere to their neighbouring part without the need to add a supplementary adhesive mea n in between the parts. I n other embodiments, if the top and/or bottom part has an adhesive property, it ca n attach with its top Si, and/or bottom S ₂ i surface to the first and/or second glass pane without the need of an additional attachment mean. I n other words, the coupling mem ber ca n be understood as an element comprising a number of parts that are adhesively interconnected together for forming a connecting element that is attached with one end to the first glass pane and attached with another end to the second glass pane. Detailed examples of coupling members will be discussed below when discussing detailed embodiments of the invention.

The coupling member according to the invention is characterized in that from the plurality of adhesively interconnected parts, there is at least a first part for stiffening the coupling member and comprising a rigid material, and at least a second part for releasing stress resulting from climatic loads and comprising a viscoelastic polymer. Hence, the coupling member according to the invention comprises at least two parts comprising a different material, a rigid material and a viscoelastic polymer. The coupling member according to the invention preferably comprises at least two and at most three pa rts comprising a rigid material and a viscoelastic polymer. The use of two or three parts is advantageous in terms of manufacturing efficiency.

In the further description below, the at least first part and the at least second part will also be named stiffening part and viscoelastic part, respectively. In preferred embodiment, the first part consists of the rigid material and the second part consists of the viscoelastic polymer.

This first part is comprising a rigid material having a Young's modulus equal or larger than 0.5 GPa, preferably equal or larger than 0.8 GPa or more preferably equal or larger than 1.0 GPa. The Young's modulus is a well-known quantity that can be measured according to methods known by the skilled person such as for instance according to ASTM D 638 and D 618 (Procedure A or B) in the case of polymers.

The at least first part comprising the rigid material is stiffening the coupling between the first and second glass pane to have a stiff coupling to improve the resistance to for example pushing and/or pulling of the wind as discussed above. Examples of a rigid material having a Young's modulus equal or larger than 0.5 GPa are rigid polymers, metals, glasses or ceramics. In some embodiments, the density of the rigid material is equal or larger than 0.5 g/cm ³ , preferably equal or larger than 0.8 g/cm ³ , more preferably equal or larger than 1.0 g/cm ³ .

The rigid material is preferably a polymer having a Young's modulus equal or larger than 0.5 GPa and more preferably a polymer having further a density equal or larger than 0.5 g/cm ³ . Polymers advantageously limit the thermal bridges between the glass pane in contact with the exterior atmosphere and the one in contact with the interior atmosphere of a building.

From the plurality of adhesively interconnected parts, there is at least a second part for releasing stress resulting from climatic loads. This second part comprises a viscoelastic polymer. Viscoelastic has here its general meaning, i.e. the ability of exhibiting both viscous and elastic characteristics when undergoing deformation. The advantage of using at least a second viscoelastic part is that it has both elastic and viscous characteristics. The current invention makes use of these viscoelastic properties to develop a coupling member that at the same time is stiff to resist to for example short term loads and at the same time is sufficiently deformable for example at higher temperatures or longer time scale to deal with stress resulting from climatic loads generally occurring over a longer time scale. The viscoelastic part advantageously makes the coupling member resistant to fatigue.

The viscoelastic polymers of the invention have a Young's modulus lower than 0.5 GPa. Preferred viscoelastic polymers according to the invention have additionally a loss coefficient of at least 0.1, preferably at least 0.3, more preferably at least 0.5. The loss coefficient has here its general meaning, it is a dimensionless quantity defining the degree to which a material dissipates vibrational energy and is measured by dynamic mechanical analysis such as described in ASTM D 4065 and D 618 (Procedure A or B).

Non exhaustive examples of viscoelastic polymers suitable for the present invention are polyurethanes, polyethylene, ethylene vinyl acetate copolymer (EVA), PVB, neoprene, isoprene, polyisobutene, acrylics, silicones.

Some of these viscoelastic polymers such as polyisobutene have an intrinsic adhesive property and will adhere with neighbouring parts or attach to the glass pane by themselves. Others such as silicones are applied uncured and have intrinsic adhesive property once cured. Yet others will be used in the form of a double-sided adhesive tape in which the core of the tape is made of the viscoelastic polymer such as an acrylic polymer, a polyurethane, a polyethylene that can be in the form of a foam, preferably the core of the tape is made of an acrylic polymer or an acrylic foam.

It should be noted that some big classes of polymers such as acrylics and polyurethanes for instance may appear both as rigid polymers and as viscoelastic polymers. It is known to the skilled person that the large variety of monomers available to prepare them allows for multiple combinations leading to polymers that can either belong to the rigid polymers or to the viscoelastic polymers depending on the choice and relative amounts of monomers. It is advantageous in the present invention to use a rigid material and a viscoelastic polymer that are free of solvents or volatile organic materials (VOC) so as to avoid a possible fogging effect in the interspace. By free of VOC is meant that the materials comprise less than 0.1wt% of VOC, they preferably comprise less than 1000 ppm VOC.

The inventors have found that by combining the first rigid part with a second viscoelastic part, a coupling member is obtained that stiffens the coupling between the first and second glass pane and that is not fully blocking the two glass panes together. The additional viscoelastic part allows for some deformation, depending on the temperature and the speed of the load application. Hence, the viscoelastic part acts as a stress release component for releasing stress resulting from climatic loads improving so the fatigue resistance of the coupling member. For example, when the ambient temperature is increasing the gas inside the sealed interspace will expand and thanks to its properties, the viscoelastic part will allow for the glass panes to move with respect to each other and release stress in comparison with a system that do not comprise a viscoelastic part.

The coupling member according to the invention is not limited by the number of adhesively interconnected parts or by any order of the stiffening and viscoelastic part. The coupling member comprises at least one stiffening part and at least one viscoelastic part as defined above.

In some embodiments according to the invention wherein a coupling member comprises more than one stiffening part, the stiffening parts comprise the same or different rigid materials.

In further embodiments according to the invention wherein a coupling member comprises more than one viscoelastic part, the viscoelastic parts comprise the same or different viscoelastic polymers.

The figures 8a to 8c illustrate examples of various coupling members having adhesively interconnected parts comprising at least a stiffening part and a viscoelastic part. For example, the IGU shown on Fig. 2 and Fig. 8a comprises a coupling member comprising two adhesively interconnected parts: a part 9 comprising a viscoelastic polymer is attached to the first glass pane 2 and is also adhesively interconnected with a stiffening part 8, which is in turn attached to the second glass pane 3. The example shown on Fig. 4 and Fig. 8b illustrates an IGU with a coupling member comprising three adhesively interconnected parts: a middle part 9 comprising a viscoelastic polymer that is adhesively interconnected with two outer stiffening parts 8, 10 and wherein these two outer parts are attached to the glass panes. In embodiments, these two outer stiffening parts 8, 10 can either comprise the same rigid material or the two stiffening parts can comprise a different material. A further example is illustrated on Fig. 8c where the coupling member comprises three adhesively interconnected parts wherein the middle part 8 is a stiffening part and the two outer parts 9, 11 are viscoelastic parts. In embodiments, these two viscoelastic parts 9, 11 can either comprise the same viscoelastic polymer or they can comprise a different viscoelastic polymer. In embodiments, the coupling members can have various shapes such as a cylindrical shape as illustrated on Fig.7a, Fig.7b and Fig.7c or for example a parallelepiped as shown on Fig.9a and 9b.

In other embodiments according to the invention, the top surface Si, and the bottom surface S ₂ i of the plurality of adhesively interconnected parts have a different surface size. An example of such an embodiment is schematically illustrated on Fig.9c where the coupling member has the shape of a trapezoidal prism such that the top and bottom surfaces have a different surface size.

Yet in other embodiments, a viscoelastic part can be divided in several non- continuous sections that are adhesively interconnected with a stiffening part. The characteristics of the coupling members such as their number, size, shape and location in the interspace can vary from one IGU to another IGU. These characteristics of the coupling members depend on various factors such as the size of the glass panes, their relative thicknesses, the impact on the thermal transmittance (U value) and aesthetic aspects. Fig. 5 and Fig. 6 illustrate examples of IGU's comprising two and six coupling members, respectively. I n fig. 1, an IGU is shown with one coupling member, which in that case is generally placed in the middle of the glass pane where the deflections are larger. I n some embodiments, generally when using smaller sized coupling members patterns, characters or letters can be created, which ca n add a n additional functional value and/or an additional aesthetic value to the IGU's.

When determining the number and the size of the coupling members, the impact on the U value ca n be taken into account. To limit the negative im pact on the U value due to the coupling mem bers, the sum of the top Si, (S _to ti) and the sum of the bottom S ₂ i (Stot ₂ ) surfaces of each of the one or more coupling members may be limited. For a first and second glass pa ne having a surface of respectively SI and S2, S _to ti < O.lOxSl and Stot ₂ < 0.10xS2,. I n preferred embodiments, S _to ti<0.05xSl a nd S _to t ₂ <0.05xS2. The surface S of a glass pane is to be understood as the total surface within the contours of the glass pa ne, for example, as shown on Fig. 5, for a rectangular surface S= LI x L2, with LI and L2 being the length and width of the glass pane. In some embodiments, the surfaces SI and S2 of an IGU are not necessarily equal to each other, e.g. when stepped glazing is applied.

I n embodiments, the rigid material of the at least one first part and/or the viscoelastic polymer of the at least second part is transparent. The term "transparent" denotes a property illustrating the percentage TL (light transmission) of visible light transmitted through a material in the visible spectrum of at least 1%. Preferably, transparent relates to a TL property of at least 10%. Ideally, transparent denotes a TL of at least 50%.

Transparent rigid materials ca n be selected from a glass or a rigid transparent polymer having a Young's modulus equal or larger than 0.5 GPa or combinations of them. Some examples of glass are soda-lime glass, alumino-silicate glass, boro-silicate glass. Examples of transparent polymers that can be used as a transparent rigid material for the stiffening part are a polymethyl methacrylate (PM MA), a polycarbonate (PC), a polystyrene (PS), a polyvinyl chloride (PVC), a polyamide (PA), a polyetherimide (PEI), a polyethylene terephthalate (PET), a polyurethane, an acrylonitrile butadiene styrene copolymer (ABS), a styrene acrylonitrile copolymer (SAN), a styrene methyl methacrylate copolymer (SMMA), and any mixtures of these; or a crosslinked resin. Composites of glass and polymers are also suitable.

Crosslinked resins are known to the skilled person and are three dimensional networks obtained by the crosslinking of low molecular weight species either by reaction with a curing agent also known as crosslinker or upon exposure to UV radiations (UV) or electron beam (EB). Examples of such resins are epoxy resins, polyurethane resins, UV or EB curable resins. In the present invention, the precursors of the crosslinked resin may be transparent or not provided that the crosslinked resin is transparent. Preferably, the transparent rigid material is chosen from a PMMA, a PC, a PS, a PVC or a mixture of any of these polymers or a crosslinked resin. More preferably, the transparent rigid material is chosen from a PMMA, a PC or a combination of these polymers.

It should be noted that some polymer mixtures, some copolymers and some semi- crystalline polymers can be opaque and non-transparent due to a dispersed phase or due to the presence of crystallites. Hence it is possible that not all compositions of the listed polymers mentioned above are transparent. The person skilled in the art is capable to identify what composition is transparent and hence identify if a given polymer falls within the claimed transparent polymers. Examples of transparent viscoelastic polymers are ethylene vinyl acetate copolymer

(EVA), PVB, polyurethanes, polyethylene, polyisobutene, acrylics, silicones. In some embodiments, transparent viscoelatic polymers will be used in the form of a double- sided adhesive tape in which the core of the tape is made of the viscoelastic polymer, preferably an acrylic polymer or an acrylic polymer foam. In particular embodiments, both the rigid material and the viscoelastic polymer are transparent, preferably the entire coupling member is transparent. In these embodiments, the coupling member preferably comprises at least two and at most three parts comprising a rigid material and a viscoelastic polymer. The use of two or three parts is advantageous in terms of manufacturing efficiency. Furthermore, limiting the number of piled parts possibly having different refractive indexes advantageously limits the optical distorsion through the assembly.

In some other embodiments, some parts of the coupling member or the entire coupling member may be opaque or even coloured.

Yet in some other cases, when several coupling members are used, they may all be of the same kind or they can be any combination of transparent, opaque and coloured coupling members. The choice may be mainly directed by aesthetic and visual reasons while the mechanical effects of the coupling member remain the same. In embodiments according to the invention the gap G, illustrated on Fig. 8a, being the distance between the first and the second glass pane has a typical value between 6 and 32 mm. The thicknesses of the adhesively piled and interconnected parts are adapted such that the plurality of piled parts fit in the gap G such that the top and bottom surfaces of the pile can be attached to the first and second glass pane, respectively. The one or more coupling members are avoiding that the glass panes are touching each other even in case of large deformations. In consequence, in some embodiments the gap G can be lower than 6 mm while it must remain sufficiently large to ensure the thermal insulation role of the IGU. It may be for instance as low as 3 mm.

In embodiments, triple glazing IGU's are used to improve the U value of the IGU. In these embodiments, a third glass pane is provided and a second edge spacer assembly is further configured for sealingly coupling the second and the third glass pane to form a second hermetically sealed interspace between the second and the third glass pane. One or more further coupling members are disposed in the second interspace. In this way, the first, second and third glass panes are coupled together to have an improved resistance to the above discussed short term mechanical stresses and at the same time still withstand the long term climatic loads, also discussed.

Compared to known standard manufacturing processes of classical gas-filled IGU's, additional steps related to the coupling members is added to the manufacturing process for gas-filled IGU's comprising the coupling members. The IGU manufacturing process generally comprises steps of cleaning the glass panes, positioning and fastening the edge spacer, assembling the glass panes together, injection of the sealant around the edge spacer and adding the insulation gas. For the IGU's according to the invention, a first additional step is provided of positioning the coupling member(s) before the glass panes assembly. Another step of attaching the coupling member(s) to the glass panes is performed during or after the glass panes assembly. In some embodiments, the multiple piled and adhesively interconnected parts can be preassembled before positioning the coupling member(s). In other embodiments, for example for a coupling member as shown on Fig. 7b wherein the outer parts are two stiffening parts, these parts can first be attached to each of the glass panes and in a further step the stress release part can be added. For example, for a coupling member as shown on Fig. 7b, if the two stiffening parts are made of glass, these stiffening parts can for example be attached to the glass panes by a glass welding process, or if the two stiffening parts are made of a crosslinked resin, the precursors can be molded and crosslinked on each glass pane. Yet another possibility is to apply a hot melt on the glass pane.

According to a further aspect of the invention, a glazed assembly is provided comprising one or more gas-filled IGU's according to the invention. By glazed assembly is meant any glazed construction comprising one or more gas-filled IGU's according to the invention for interior or exterior application such as a window, a door, a partition wall, a curtain wall, a roof , a temperature conditioned product presentation appliance such as a refrigerated cabinet, and the like.

The IGU's according to the invention are suited for different types of glazed assemblies, particularly for large size glazed assemblies or glazed assemblies comprising thin glass. The coupling member interconnects the glass panes that will behave like a thicker glass pane and better resist short term stresses. It allows hence for the making of larger size glazed assemblies that are otherwise not technically feasible because of the glass panes thickness that would be needed, or that are otherwise realized by partitioning the large glazed area in different smaller sections. For the same reason, it also allows for the making of glazed assemblies with thinner glass panes. They are also particularly suited for use in frameless glazed assemblies. By frameless glazed assembly is meant a glazed assembly having a higher transparent surface than a standard one by elimination of some or all frame elements. These assemblies may have a limited resistance to bending under load because of the elimination of said frame elements. For the same reason as above, the IGU's according to the invention may advantageously improve the resistance to short term stresses of such frameless assemblies and also allows the use of larger size or thinner glass panes. Therefore the present invention also provides a frameless glazed assembly comprising one or more gas-filled insulating glazing units according to the invention. In some embodiments, the frameless glazed assembly comprises at least two gas- filled insulating glazing units that are placed contiguous to each other, i.e. next to each other and in contact to each other. In this case, contiguous edges of contiguous IGU's are free from any frame element and the edge spacer assemblies along said contiguous edges are transparent. An example of such an application is a ribbon window or a curtain wall. In this case, depending on the wished aesthetics aspect, some parts of the coupling member or the entire coupling member may be opaque or even coloured or it may be transparent. When several coupling members are used, they may all be of the same kind orthey can be any combination of transparent, opaque and coloured coupling members.

It is a further aspect of the invention to provide a glazed assembly, particularly a window, a roof or a curtain wall in a building, comprising a gas-filled IGU according to the invention and one or more wind brace coupled to the IGU.

A wind brace is a device well known in the art to resist the wind pressure normal to the glass panes. The wind braces are in standard systems placed inside the building and anchored to the floor, the ceiling or to a wall. The wind braces are further fastened with the glass panes and the fastening is configured to resist the wind pressure on the glass pane being in contact with the exterior of the building. The fastening is typically made at or near the edges of the edge spacer assembly in order to obtain an optimum performance of the brace as an element to resist the wind loads. In the present invention, the one or more wind braces is fastened to the IGU to the one of first or second glass pane that is in contact with the interior atmosphere and at a location where one of said one or more coupling members is coupling the first glass pane with the second glass pane. The interior atmosphere is here the atmosphere inside the building. Hence, the IGU's according to the invention allow more flexibility than classical IGU's to use and locate the wind braces. Furthermore, the wind braces do not necessarily need to be coupled to the edges of the glass panes as required with classical IGU's. A further advantage is that the fastening of the wind brace to the IGU is made to the interior glass pane, in contrast to the classical IGU's without the coupling members that need a fastening up to the exterior glass pane. As a result, by only having to make the fastening of the wind brace to the interior glass pane, thermal bridges are reduced.

In embodiments according to the invention, the wind brace comprises a support structure which is the part that is anchored to the floor, the ceiling or a wall and a fastening part for fastening the support structure with the one said first or said second glass pane in contact with the interior atmosphere at a location where one of said one or more coupling members is coupling the first glass pane with the second glass pane. The support structure can for example be made of glass for aesthetic reasons and the fastening part can be made of another material such as steel, aluminium, or a composite. This is schematically illustrated on Fig. 10a where a top view of a wind brace 20 is shown comprising a support structure 21 and a fastening part 22 fastening the support structure 21 with the IGU

The support structure of the wind brace does not necessarily need to be positioned in front of a coupling member as long as a connection is provided between the support structure and the glass pane at the level of a coupling member through the fastening part. It is illustrated on Fig. 10b where the fastening part 22 is fastened with one end to the support structure 21 and with another end to the glass pane that is in contact with the interior atmosphere at a location of one of the one or more coupling members 7.

The present invention has been described in terms of specific embodiments, which are illustrative of the invention and not to be construed as limiting. More generally, it will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and/or described hereinabove. The invention resides in each and every novel characteristic feature and each and every combination of characteristic features. Reference numerals in the claims do not limit their protective scope.

Use of the verbs "to comprise", "to include", "to be composed of", or any other variant, as well as their respective conjugations, does not exclude the presence of elements other than those stated.

Use of the article "a", "an" or "the" preceding an element does not exclude the presence of a plurality of such elements.

Examples

The invention will now be illustrated by some examples that are in no way limiting the scope of the invention.

Deformation of IGU induced by punctual load (short term stress) The test consists in measuring the deformation of a rectangular IGU placed horizontally and supported linearly on the small sides, with and without punctual load of 40 kg in the middle of the IGU. The test aims at simulating the deformation of the IGU under short term stress.

The IGUs are 148cm x 123cm with about 12mm air gap between the glass panes. The glass panes are 4mm thick, the aluminum spacer is from Alupro, 6,5mm high and 11,5mm wide, butyl is GD115 from Kommerling and the polyurethane sealant is JS442MF from Tremco lllbruck. The polyurethane height is about 4mm. The distance between the supports is 145,5cm.

The deformation of the upper glass pane is measured in the center of the IGUs, 1-2 minutes after loading the IGUs and data are in mm. The deformation is measured as the distance between the upper glass pane surface and a horizontal reference ruler placed on the upper glass pane surface. Comparative Example 1:

The test is performed on an IGU as described above without coupling member. Example 1:

An IGU as described above is prepared and a linear coupling member is placed in the interspace between the glass panes before assembly of the IGU. The coupling member is 120cm long, 10mm wide, 12mm high. It consists of 3 piled and adhesively interconnected parts: 2 stress release parts each made of 2mm thick VHB 4918 from 3M separated by one stiffening part, which is made of a 8mm thick transparent PMMA stick. The coupling member is located parallel to the small sides in the middle of the long sides of the IGU.

Example 2:

An IGU as described above is prepared and a linear coupling member is placed in the interspace between the glass panes before assembly of the IGU. The coupling member is: 145cm long, 10mm wide, 12mm high. It consists of 3 piled and adhesively interconnected parts: 2 stress release parts each made of 2mm thick VHB 4918 from 3M separated by one stiffening part, which is made of a 8mm thick transparent PMMA stick. The coupling member is placed parallel to the long sides in the middle of the small sides of the IGU.

The results of the tests are presented in Table 1. Table 1: Deformation of the IGUs with and without additional load

Deformation of upper Comparative Ex 1 Exl Ex2

glass pane no additional load 4,6 <4* <4*

40kg additional load 7,8 6,9 6,9 * The device used to measure the deformation has a limit of detection of 4 mm and cannot measure precisely deformations below 4mm. Such deformations below 4 mm are noted <4 in Table 1.

In horizontal position and without additional load, the upper glass pane of the IGU of Comparative Example 1 is already deformed of more than 4mm by its own weight.

In the same conditions, the deformation of the IGU's of Examples 1 and 2 according to the invention is below 4 mm. Already without additional load, the coupling member of the invention reduces the deformation of the upper glass pane of the IGU.

When a load of 40 kg is applied on the IGUs, the deformation of the upper glass pane of Examples 1 and 2 is limited to 6,9mm instead of 7,8mm in Comparative Example 1. The deformation of the upper glass pane of the IGU's according to the invention is significantly reduced thanks to the presence of coupling members when compared to an IGU without coupling member.

The IGUs according to the invention have an improved resistance to short term mechanical stresses.

Deformation of IGU induced by climatic load such as temperature variation of air placed between the glasses and impact on IGU tightness (long term stress).

The tests are performed according to the standard EN1279-2.

IGUs are prepared according to the previous section, but dimensions are smaller: 350mm x 500mm, according to standard EN1279-2.

Comparative Example 2 :

The test is performed on an IGU without coupling member.

Example 3:

An IGU is prepared as described above and a linear coupling member is placed in the interspace between the glass panes before assembly of the IGU. The coupling member is: 25cm long, 10mm wide, 12mm high. It consists of 3 piled and adhesively interconnected parts: 2 stress release parts each made of 2mm thick VHB 4918 from 3M separated by a stiffening part made of 8mm thick tra nsparent PM MA stick. The coupling member is placed parallel to the small sides in the middle of the long sides of the IGU

5 Example 4 :

An IGU is prepared as described above and 2 linear coupling members are placed in the interspace between the glass pa nes before assembly of the IGU. The coupling members are: 5cm long, 10mm wide, 12mm high. Each consists of 3 piled and adhesively interconnected parts: 2 stress release parts each made of 2mm thick VHB 4918 from 3M 0 separated by a stiffening part made of 8mm thick tra nsparent PM MA stick. The coupling members are placed parallel to the small sides, at 10 cm from each small side of the IGU.

IGUs are placed in an ageing chamber to perform ageing test according to EN1279-2 comprising thermal cycling and long term stress at high temperature (7 weeks at 58°C). The distance between the glass panes is measured at 23°C before test and at 5 the last day of test, when the samples are at 58°C and 95% relative humidity. After the ageing test, the IGUs are destroyed to measure the moisture penetration. The moisture penetration is characterized by I index and must be lower than 20%.

The results of the tests are presented in Table 2.

Table 2: Results of simulation of climatic load

Comparative Ex 2 Ex3 Ex4

Distance between glasses at 23°C 11,6 11,5 11,6 before test at the centre (mm)

Distance between glasses at 58°C at 13,7 13,1 12,2 the last day of the test at the centre

(mm)

1 index <20% YES YES YES Before ageing test, the distance between the glass panes of the IGUs of Comparative Example 2 and Examples 3 and 4 at 23°C is similar.

After ageing test, the distance between the glass panes of the IGU of Comparative Example 2 measured in the centre of the IGU is of 13,7mm at 58°C. Because of air dilatation and IGU tightness, the internal pressure makes the two 4mm thick glass panes deform.

Thanks to the presence of one coupling member, this distance is limited to 13,1 mm in Example 3. This distance is further reduced to 12,2m m at 58°C with the help of two coupling members in Example 4. The IGUs of Examples 3 and 4 comprising one or two coupling mem bers according to the invention have a reduced deformation when compared to an IGU without coupling member.

On top of that, all the coupling members still adhere on both glass panes of Exa mple 3 and Example 4 at 58°C. Thus, the IGUs according to the invention also resist to long term stress, such as high temperature (58°C) induced deformation during 7 weeks.

The goal of EN1279-2 is to evaluate moisture penetration in the IGUs. All the tested IGUs (Com parative Ex2, Ex3 a nd Ex4) pass successfully this test. I ndeed, they a ll show I index lower than 20%. Hence, the IGUs of Examples 3 and 4 according to the invention withstand long term stresses (both in terms of adhesion of the coupling members to the glass panes and moisture penetration) and even have an improved resistance to deformation under such long term stresses.