EA040555B1 - ASYMMETRIC VACUUM INSULATED GLAZING UNIT - Google Patents

Description

1. Technical field to which the invention belongs

The present invention relates to a vacuum insulating glazing unit where the glass panels have different thicknesses.

2. Background of the invention

Vacuum insulating glazing units are recommended due to their high performance thermal insulation. A vacuum insulating glazing unit typically consists of at least two glass panels separated by an interior space in which a vacuum has been created. In general, in order to achieve high performance thermal insulation (heat transfer coefficient U is U<1.2 W/m2K), the absolute pressure inside the glazing unit is usually 0.1 mbar or less, and usually at least one of the two glass panels is coated with a low-emissivity layer. To obtain such a pressure inside the glazing unit, a hermetically connecting seal is placed on the periphery of two glass panels and a vacuum is created inside the glazing unit using a pump. Separate spacers are placed between two glass panels to prevent indentation into the glazing unit under atmospheric pressure (due to pressure difference inside and outside the glazing unit).

Vacuum insulating glazing units must be carefully sized to withstand various external stresses. Most of the external stresses considered in sizing, in particular vacuum insulating glazing units, are thermal stress caused by temperature differences between the outside and inside environments and stress caused by atmospheric pressure.

The glass panel facing the internal environment acquires a temperature approximately equal to the temperature of the internal environment, and the glass panel facing the external environment acquires a temperature approximately equal to the temperature of the external environment. Under the most severe weather conditions, the difference between indoor and outdoor temperatures can reach 40°C or more. The temperature difference between indoor and outdoor environments can lead to induced thermal stress inside the glass panels. In some severe cases, for example when the temperature difference is >40°C, the resulting thermal stress can lead to the destruction of the vacuum insulating glazing unit. In order to withstand this induced thermal stress, various solutions in the art have been envisaged, such as increasing the thickness of both glass panels. Another solution is proposed in JP 2001316137, which teaches how to improve vacuum insulating glazing units so that deformation or warping does not occur even when glass panels are exposed to strong sunlight. JP 2001316137 describes the creation of a glazing in which an inner glass panel located on the inside is thicker than an outer glass panel. In contrast, JP 2001316138 describes an opposite VIG design in which the outer glass panel located on the outside is thicker than the inner glass panel for improved impact resistance and acoustics.

However, none of the solutions in the art solves the technical problem of improving the resistance to induced thermal stress in vacuum insulating glazing units, while the glass panels are exposed to the temperature difference between the external and internal environments. In addition, the prior art does not have a solution to the technical problem of atmospheric pressure stress at stud locations, and even how to provide a vacuum insulating glazing unit that exhibits improved resistance to this combined external stress while maintaining high performance thermal insulation.

3. Brief description of the invention

The present invention relates to a vacuum insulating glazing unit extending along a plane P defined by a longitudinal X axis and a vertical Z axis, and having a width W measured along the longitudinal X axis and a length L measured along the vertical Z axis. The length L of the vacuum insulating glazing unit is equal to or greater than 800 mm (L>800 mm), and the width W of the vacuum insulating glazing unit is equal to or greater than 500 mm (W>500 mm). Vacuum insulating glazing unit contains

a) a first glass panel having a thickness Z1 and a second glass panel having a thickness Z2, where Z1 is greater than Z2 (Z1>Z2) and where the ratio of the thicknesses Z1/Z2, the thickness Z1 of the first glass panel to the thickness Z2 of the second glass panel, equal to or greater than 1.10 (Z1/Z2>1.10); the thicknesses are measured in the direction perpendicular to the plane P, the first glass panel and the second glass panel are annealed float glass panels;

b) a set of separate spacers located between the first and second glass panels, maintaining the distance between the first and second glass panels and forming an array with a pitch λ; step λ is in the range from 10 to 40 mm (10 mm<λ<40 mm);

c) a hermetically connecting seal (4) sealing the gap between the first and second glass panels along their perimeter;

d) internal volume V, formed by the first and second glass panels and a set of separate

- 1 040555 spacers and closed with a hermetically connecting seal, and at the same time it is vacuumed with an absolute pressure of less than 0.1 mbar.

In the vacuum insulating glazing unit according to the present invention, the thickness Z2 of the second glass panel is equal to or greater than 4 mm (Z2>4 mm) and equal to or greater than (λ-15 mm)/5(Z2>(λ-15 mm)/5).

The present invention further relates to a partition separating a first space with a first temperature Temp1 from a second space with a second temperature Temp2, where Temp1 is lower than Temp2. Said partition comprises an opening closed by a vacuum insulating glazing unit according to the present invention, preferably with the first glass panel facing the first space. The present invention further relates to the use of a vacuum insulating glazing unit according to the present invention for closing the opening of such a partition.

Other aspects and advantages of the embodiments will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate by way of example the principles of the described embodiments.

4. Brief description of graphic materials

In FIG. 1 is a cross-sectional view of a vacuum insulating glazing according to one embodiment of the present invention.

In FIG. 2 shows the results of a finite element simulation of the maximum thermal stress correlation (σΔT Max) calculated for glass panels at AT=40°C as a function of the Z1/Z2 thickness ratio.

5. Detailed description of the invention

It is an object of the present invention to provide a vacuum insulating glazing unit (hereinafter referred to as VTG) that exhibits high performance thermal insulation and improved resistance to a combination of stresses caused by temperature differences between indoor and outdoor environments and caused by atmospheric pressure.

Surprisingly, it has been found that when the vacuum insulating glazing unit according to the present invention is asymmetric, i.e. when the first glass panel is thicker than the second glass panel (Z1>Z2) and therefore has a certain Z1/Z2 ratio and its dimensions are carefully defined by a specific dimension including a minimum length (L) and a minimum width (W), a specific spacer spacing ( λ) and the specific thickness of the second glass panel (Z2), and with the thickness value of the second glass panel carefully determined to match the specific relationship between the minimum thickness of the second panel and the pitch, this provides better resistance to combined stresses than the corresponding symmetrical vacuum insulating glazing with the same overall thickness.

The vacuum insulating glazing unit according to the present invention is hereinafter referred to as asymmetric VTG.

The present invention relates to a VIG typically comprising a first glass panel and a second glass panel connected to each other by means of a set of separate spacers that hold said panels at a certain distance from each other, typically in the range of 50 to 1000 µm, preferably 50 to 500 microns, more preferably from 50 to 150 microns, and an internal space containing at least one first cavity in which there is a vacuum with an absolute pressure of less than 0.1 mbar, and the specified space is closed by a peripheral hermetically connecting seal placed on the periphery of the glass panels around specified interior space.

The present invention relates to a VIG extending along a plane P defined by a longitudinal X-axis and a vertical Z-axis, and having a width W measured along the longitudinal X-axis and a length L measured along the vertical Z-axis. The length L of an asymmetric VIG according to the present invention is equal to or more than 800 mm (L>800 mm). In a preferred embodiment, the length L of the asymmetric VIG is equal to or greater than 1000 mm (L>1000 mm), preferably equal to or greater than 1200 mm (L>1200 mm). The width W of the asymmetric VIG according to the present invention is equal to or greater than 500 mm (W>500 mm), preferably equal to or greater than 600 mm (W>600 mm), more preferably equal to or greater than 800 mm (W>800 mm), even more preferably equal to or greater than 1000 mm (W>1000 mm), ideally equal to or greater than 1200 mm (W>1200 mm).

As shown in FIG. 1, the asymmetric VIG (10) according to the present invention contains

a) a first glass panel (1) having a thickness Z1 and a second glass panel (2) having a thickness Z2, the thicknesses being measured in a direction perpendicular to the plane P;

b) a set of separate spacers (3) located between the first and second glass panels, maintaining the distance between the first and second glass panels and forming an array with a pitch λ;

c) a hermetically connecting seal (4) sealing the gap between the first and second glass panels along their perimeter;

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d) an internal volume V formed by the first and second glass panels and a set of separate spacers and closed by a hermetically bonding seal, and the absolute vacuum pressure is less than 0.1 mbar.

In the present invention, Z1 is greater than Z2 (Z1>Z2), so the thickness ratio Z1/Z2 for the thickness Z1 of the first glass panel and the thickness Z2 of the second glass panel is equal to or greater than 1.10 (Z1/Z2>1.10). In a preferred embodiment, the thickness ratio Z1/Z2 is equal to or greater than 1.30 (Z1/Z2>1.30) and implements the equation Z1/Z2>Z1/(Z1-2.10). In a further preferred embodiment, the thickness ratio Z1/Z2 is equal to or greater than 1.55 (Z1/Z2>1.55), preferably in the range of 1.60 to 6.00 (1.60<Z1/Z2<6.00 ), preferably from 2.00 to 4.00 (2.00<Z1/Z2<4.00).

In the present invention, the thickness Z2 of the second glass panel of the asymmetric VIG is equal to or greater than 4 mm (Z2>4 mm). Generally, the thickness Z2 of the second glass panel may be equal to or greater than 5mm (Z2>5mm) and even equal to or greater than 6mm (Z2>6mm) and not more than 10mm, preferably not more than 8mm. However, in order to improve resistance to induced thermal stress, it is preferable to keep the thickness Z2 of the second panel to a minimum.

In the present invention, the spacing between the individual spacers located between the first and second glass panels and maintaining the distance between the first and second glass panels, also called pitch λ, is in the range of 10 to 40 mm (10 mm<λ<40 mm), preferably pitch is in the range from 15 to 35 mm (15 mm<λ<35 mm), more preferably between 20 and 30 mm (20 mm<λ<30 mm).

Surprisingly, it has been found that there is a critical relationship between the minimum thickness of the second glass panel and the pitch when creating asymmetric VIGs. Indeed, it has been found that the thickness Z2 of the second panel must fulfill the equation Z2>(λ-15 mm)/5 in order to provide excellent resistance to the combination of thermal induced stress and atmospheric pressure induced stress. Thus, the present invention is based on the unexpected discovery that optimum resistance to combined thermal induced and atmospheric pressure induced stresses can be achieved by a carefully sized asymmetric VIG configuration.

For the purposes of the present invention, only tensile stresses on the outer surfaces of the glass panels are taken into account when creating asymmetric VIGs. Indeed, as is known to those skilled in the art, it is the tensile stress that can cause cracks in glass panels when the tensile strength is reached. Moreover, only the tensile stress on the outer surface of the panels is taken into account. The outer surfaces of the panels are the surfaces of the glass panels that face the outside of the VTG. The internal volume of the V VTG is under vacuum and therefore essentially free of water. The person skilled in the art is well aware that the inner surfaces of the panels, i. those facing the interior volume V VIG are substantially more mechanically stable in the absence of water vapor.

Induced thermal stress

The induced thermal stress occurs when there is a temperature difference between the first glass panel (1, T1) and the second glass panel (2, T2) and increases as the difference between T1 and T2 increases. The temperature difference (AT) is the absolute difference between the average temperature T1 calculated for the first glass panel (1) and the average temperature T2 calculated for the second glass panel (2). The average temperature of the glass panel is calculated from numerical simulations known to those skilled in the art. The resulting thermal stress becomes even more problematic - up to the destruction of the VIG, when such an absolute temperature difference between glass panels reaches 30°C and even more when the absolute temperature difference is higher than 40°C in severe conditions. The temperature of the internal environment is, as a rule, from 20 to 25°C, while the temperature of the external environment can vary from -20°C in winter to +35°C in summer. Therefore, the temperature difference between the indoor environment and the external environment can reach more than 40° C. under severe conditions. Therefore, the temperature difference (AT) between the average temperature T1 calculated for the first glass panel (1) and the average temperature T2 calculated for the second glass panel (2) can also reach more than 40°C.

The thermal stress induced was calculated at AT=40°C indicating severe conditions, and the average temperature T1 of the first panel is lower than the average temperature T2 of the second panel (T1<T2).

The present invention is based on the surprising discovery that reduced induced thermal stress can be achieved by carefully sizing an asymmetric VTG configuration where the ratio Z1/Z2 for a thicker glass panel, Z1, to that of a thinner glass panel, Z2, must be equal to or greater than 1.1 and should preferably be equal to or greater than 1.30 (Z1/Z2>1.30). Additionally, it has been found that the higher the thickness ratio is, the greater the reduction in induced thermal stress will be, as shown in FIG. 2 depicting the results of FEM simulations of the maximum correlation

- 3 040555 thermal stress (σΔΤ Max), calculated for glass panels at AT=40°C and T1<T2 depending on the ratio of thicknesses Z1/Z2.

In FIG. 2, the maximum induced thermal stress value is the highest value obtained for the first and second glass panels. Thermal stress is calculated under the following conditions:

temperature AT=4O°C; AT is calculated as the temperature difference between the average temperature T1 of the first glass panel and the average temperature T2 of the second glass panel, where the average temperature of the first panel is lower than the average temperature of the second panel (T1<T2);

glass panels are annealed float glass panels made of soda-lime-silicate glass with thermal expansion coefficient CTE, CTE=8.5 10-6/°C, Young's modulus E, E=70 GPa and Poisson ratio, μ, μ=0.21;

racks are placed on a uniform square array;

the experimental VTG was tested with free edges, i.e. not located inside the additional window frame.

Induced thermal stress (σΔT) is the stress induced on VIG glass panels when said glass panels are exposed to different temperature conditions. Numerical simulation is used to calculate the thermal stress on each VIG glass panel. The finite element (FEA) model of the commercially available software Abaqus2017 (formerly called ABAQUS) was developed to simulate the behavior of the VTG when exposed to different temperature conditions. Calculations were made for glass panels fitted with a grid using C3D8R elements with 5 integration points per glass thickness. The total mesh size used was 1 cm. To achieve the AT of the present invention, a reference and constant temperature was applied to both glass panels, then one of the glass panels was subjected to a constant temperature variation while the other glass panel was maintained at the initial temperature. A mechanical joint is placed between two glass panels to provide uniform displacement of the two touching glass surfaces. Other boundary conditions have been specified to prevent motion of the rigid body of the assembly. The thermal stress caused by the temperature difference was calculated on each glass panel, and the largest value of the two is taken as the maximum and is expressed in MPa.

Stress caused by atmospheric pressure

In addition to thermal induced stress, atmospheric pressure induced stress should also be considered in order to size a VIG with high performance thermal insulation. Since a vacuum is maintained between the two VIG panels, atmospheric pressure induces a constant tensile stress on the outer surfaces of the VIG glass panel at each rack location. It is known to the person skilled in the art that for small studs, the tensile stress caused by the studs on the outer surfaces of the glass panels is independent of the size of their outer circumference. By small posts, as a rule, stands are meant having a contact surface with a glass panel, formed by their outer circumference, equal to or less than 5 mm ² , preferably equal to or less than 3 mm ² , more preferably equal to or less than 1 mm ² .

In such cases, and for uniform arrays based on a pattern using an equilateral triangle, square or hexagon, such stress caused by atmospheric pressure, also called tensile stress, can be calculated using the following formula: σ _p <011χλ ² /t ² [MPa] , where [λ] and [t] are respectively the spacing between the spacers and the thickness of the glass panels. A pitch should be understood as the shortest distance separating a given strut from any adjacent strut. In particular, for square-based uniform arrays, the tensile stress is at its maximum, and hence the following formula holds:

σp=0.11χλ ² /t ² [MPa].

It has been found that the introduction of asymmetry in the VIG provides a reduced induced thermal stress. The greater the asymmetry, the better the thermal insulation characteristics. However, asymmetry can adversely affect the performance of an asymmetrical VTG in terms of resistance to stress caused by atmospheric pressure at rack locations. This deterioration is mainly due to the fact that the second glass panel of the asymmetric VTG is thinner than the glass panels in the corresponding symmetrical VIG, which has the same overall thickness.

Combined voltage

Asymmetric versus symmetrical (ratio)

The asymmetric VIG configuration, where the ratio Z1/Z2 of the thickness Z1 of the first glass panel to the thickness Z2 of the second glass panel should be equal to or greater than 1.1 (Z1/Z2>1.1), is excellent for greatly reducing the induced thermal stress, and even more with higher

- 4 040555 thickness ratio (Fig. 2), but can greatly degrade the performance with respect to the stress caused by atmospheric pressure, which increases significantly on the surface of the second panel. However, it has surprisingly been found that by carefully sizing the asymmetric VIG by determining the minimum thickness of the second panel in relation to the pitch value, in a certain sized asymmetric VIG according to the present invention, a favorable compromise can be found between resistance to induced thermal stress and stress, caused by atmospheric pressure. It has been found that a carefully designed compromise can be found between the minimum thickness Z2 of the second panel, the thickness ratio Z1/Z2 and the distance between the uprights, i.e. step X. It was found that such a compromise can be determined by the following equation: Z2>(λ-15 mm)/5.

Therefore, the combined stress, which is a combination of thermal induced stress and atmospheric pressure induced stress, is something to consider when sizing a VTG. The term combined stress or combination of stresses should be understood as the sum of the induced thermal stress and the stress induced by atmospheric pressure. It has been found that the asymmetrical VIG designed according to the present invention exhibits a reduced combined voltage compared to the corresponding symmetrical VIG. Therefore, VIG can be designed to be even larger and/or resistant to even greater temperature differences, while still providing excellent thermal insulation.

Indeed, proper natural lighting of indoor spaces, in particular buildings, is one of the key parameters for creating a pleasant and healthy environment for people. Daylight is the most interesting source of such lighting, and it is important that building envelopes have some transparent parts to let this light into the interior of the building. Consequently, there is a trend in the market towards larger windows and transparent doors, requiring high performance thermal insulation. Therefore, there is a need to increase the size of the vacuum insulating glazing. In order to accommodate larger dimensions, it is preferable to increase the minimum thickness of the first panel to support the weight load and also to provide greater flexibility in increasing the thickness ratio between the first and second glass panels and thus provide improved thermal stress resistance.

The thickness Z1 of the first glass panel according to the present invention can generally range from 4 to 25 mm, preferably from 5 to 19 mm, more preferably from 6 to 10 mm. Furthermore, in a preferred embodiment of the present invention, the thickness Z1 of the first panel of the asymmetric VTG is equal to or greater than 4 mm (Z1>4 mm), preferably equal to or greater than 5 mm (Z1>5 mm), more preferably equal to or greater than 6 mm (Z1> 6 mm).

As shown in Table. 1A, 1B, and 1C below, the combined stress of vacuum insulating glazing units of the same size, containing the same individual spacers, spaced between glass panels at the same pitch, and having the same overall thickness, was calculated as described above for ΔT=40°C, and the average temperature T1 of the first panel is lower than the average temperature T2 of the second panel (T1<T2) for two different embodiments: one configuration is a symmetrical VIG where the first and second glass panels are the same thickness, and the second configuration is an asymmetric VIG, where the thickness Z1 of the first glass panel is greater than the thickness Z2 of the second glass panel.

Table 1A

Symmetric VIG configuration (comparative) Asymmetric configuration VIG (Within the scope of the invention) Thickness Z1 = 5 mm Z2 = 5 mm Ζ1 = 6 mm Z2 = 4 mm Size L = 1000 mm W = 1000 mm L = 1000 mm W = 1000 mm Step λ = 32 mm λ = 32 mm λ = 32 mm λ = 32 mm Ratio Z1/Z2 1 1.50 Meaning / 3.4mm

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equalized. (λ - 15 mm)/5 Thermal voltage odt = 0 MPa σ _ΔΤ =9.15 MPa odt = 0 MPa odt = 5.77 MPa Voltage from atmospheric pressure. ^σ ρ = 4.51 MPa σ _ρ = 4.51 MPa σ _ρ = 3.13 MPa σ _ρ = 7.04 MPa Combined Ocomb Ocomb Ocomb Ocomb voltage = 4.51 MPa = 13.66 MPa = 3.13 MPa = 12.81 MPa

As shown in Table. 1A above, the maximum combined stress obtained for the asymmetric VTG according to the present invention decreased to 12.81 MPa, while the corresponding symmetrical VIG shows a higher maximum combined stress of 13.66 MPa under test conditions.

Table 1B

Symmetric VIG configuration (comparative) Asymmetric configuration VIG (Within the scope of the invention) Thickness Ζ1 = 6 mm Z2 = 6 mm Ζ1 = 8 mm Z2 = 4 mm Size L = 1000 mm W = 1000 mm L = 1000 mm W = 1000 mm Step λ = 32 mm λ = 32 mm λ = 32 mm λ = 32 mm Ratio z1/z2 1 2.0 Meaning equalized. (λ - 15 mm)/5 / 3.4mm Thermal voltage odt = 0 MPa σ _ΔΤ = 8.95 MPa σ _Δ τ = 0 MPa σ _Δ τ =4.15 MPa Voltage from atmospheric pressure. σ _ρ = 3.12 MPa σ _ρ = 3.13 MPa σ _ρ = 1.76 MPa σ _ρ = 7.04 MPa Combined voltage Ocomb = 3.13 MPa Ocomb = 12.08 MPa Ocomb = 1.76 MPa Ocomb = 11.19 MPa

As shown in Table. 1B, the maximum combined stress obtained for the asymmetric VTG according to the present invention decreased to 11.19 MPa, while the corresponding symmetrical VIG shows a higher maximum combined stress of 12.08 MPa under test conditions.

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Table 1C

Symmetric VIG configuration (comparative) Asymmetric configuration VIG (Within the scope of the invention) Thickness Ζ1 = 6 mm Z2 = 6 mm Ζ1 = 7 mm Z2 = 5 mm Size L = 1000 mm W = 1000 mm L = 1000 mm W = 1000 mm Step λ = 38 mm λ = 38 mm λ = 38 mm λ = 38 mm Ratio z1/z2 1 1.4 Meaning equalized. (λ - 15 mm)/5 / 4.6 mm Thermal voltage odt = 0 MPa σ _ΔΤ = 8.95 MPa odt = 0 MPa σ _ΔΤ = 6.35 MPa Voltage from atmospheric pressure. σ _ρ = 4.41 MPa σ _ρ = 4.41 MPa σ _ρ = 3.24 MPa σ _ρ = 7.04 MPa Combined voltage Ocomb = 4.41 MPa Ocomb = 13.36 MPa Ocomb = 3.24 MPa Ocomb = 12.82 MPa

As shown in Table. 1C, the maximum combined stress obtained for the asymmetric VTG according to the present invention decreased to 12.82 MPa, while the corresponding symmetrical VIG shows a higher maximum combined stress of 13.36 MPa under test conditions.

Criticality of the relationship between the thickness of the second glass panel and the pitch

The example below (Table 2) shows that there is a critical relationship between the thickness of the second glass panel and the pitch. Surprisingly, it has been found that the minimum thickness Z2 of the second glass panel must satisfy the equation Z2>(λ-15 mm)/5 for a thickness Z2 of the second glass panel equal to or greater than 4 mm (Z2>4 mm) and a pitch λ in the range from 10 to 40 mm, in order to take advantage of the reduced combined voltage of the asymmetric VIG configuration of the present invention compared to the corresponding symmetrical VTG.

The combined voltage was calculated for symmetrical and asymmetrical VTG having a thickness outside the range of values claimed in the present invention. Thermal induced stress and atmospheric pressure induced stress were calculated as described above under the same conditions.

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table 2

Symmetric VIG configuration (comparative) Asymmetric configuration VIG (comparative) Thickness Ζ1 = 6 mm Z2 = 6 mm Ζ1 = 8 mm Z2 = 4 mm Size L = 1000 mm W = 1000 mm L = 1000 mm W = 1000 mm Step λ = 38 mm λ = 38 mm λ = 38 mm λ = 38 mm Ratio Z1/Z2 1 2.0 Meaning equalized. (λ - 15 mm)/5 / 4.6mm Thermal voltage odt = 0 MPa σ _ΔΤ = 8.95 MPa odt = 0 MPa odt \u003d 4.15 MPa Voltage from atmospheric pressure. σ _ρ = 4.41 MPa σ _ρ = 4.41 MPa σ _ρ = 2.48 MPa σ _ρ = 9.92 MPa Combined voltage Ocomb = 4.41 MPa Ocomb = 13.36 MPa Ocomb = 2.48 MPa Ocomb = 14.07 MPa

As shown in Table. 2, the maximum combined stress obtained for the asymmetric VIG reaches 14.07 MPa, while the corresponding symmetrical VIG shows a maximum combined stress of 13.36 MPa. Therefore, this example shows that the ratio between the thickness Z2 of the second panel and the pitch λ: Z2>(λ-15 mm)/5, is critical for an asymmetric VIG to perform better than a corresponding symmetrical VIG with the same overall thickness.

Criticality of VIG size

The example below (Table 3) shows this size criticality, i.e. length L and width W VIG. Surprisingly, it has been found that a VIG length L equal to or greater than 800 mm (L>800 mm) and a VIG width W equal to or greater than 500 mm (W>500 mm) are critical to obtaining the reduced combined voltage benefit of the asymmetric VIG configuration according to of the present invention compared to the corresponding symmetrical VTG.

The combined voltage was calculated for symmetrical and asymmetrical VIG, the length and width of the VIG being outside the range claimed in the present invention. Thermal induced stress and atmospheric pressure induced stress were calculated as described above under the same conditions.

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Table 3

Symmetric VIG configuration (comparative) Asymmetric configuration VIG (Within the scope of the invention) Thickness Z1 = 5 mm Z2 = 5 mm Ζ1 = 6 mm Z2 = 4 mm Size L = 400 mm W=400mm L = 400 mm W=400mm Step λ = 3 5 mm λ = 3 5 mm λ = 3 5 mm λ = 3 5 mm Ratio Z1/Z2 1 1.50 Meaning equalized. (λ - 15 mm)/5 / 4.0 mm Thermal voltage odt = 0 MPa odt = 8.20 MPa odt = 0 MPa σ _ΔΤ = 5.83 MPa Voltage from atmospheric pressure. σ _ρ = 5.39 MPa σ _ρ = 5.39 MPa σ _ρ = 3.74 MPa σ _ρ = 8.42 MPa Combined voltage Ocomb = 5.39 MPa Ocomb = 13.59 MPa Ocomb = 3.74 MPa Ocomb = 14.25 MPa

As shown in Table. 3, the maximum combined stress obtained for the asymmetric VIG, which is outside the scope of the present invention, reaches 14.25 MPa, while the corresponding symmetrical VIG shows a maximum combined stress of 13.59 MPa. Therefore, this example shows that the minimum VIG size is critical for an asymmetric VTG to perform better than a corresponding symmetrical VIG with the same overall thickness.

Partition

The asymmetric VIG according to the present invention is generally used to cover an opening in a partition such as general purpose glazing units, building wall, automotive glazing units or architectural glazing units, electrical appliances and the like. As a rule, a partition separates the external space from the internal space of the building. Preferably, the asymmetric VIG according to the present invention closes the opening of the partition separating the outer space from the inner space, whereby the first glass panel of the asymmetric VIG faces the outer space. This partition separates the first space, characterized by the first temperature Tempi, from the second space, characterized by the second temperature Temp2, while Temp1 is lower than Temp2. The temperature of the interior is usually between 20 and 25°C, while the temperature of the outside can vary from -20°C in winter to +35°C in summer. Therefore, the temperature difference between the inside and the outside can generally be as high as 40°C under severe conditions. The temperature (T1, T2) of each glass panel of the asymmetric VIG according to the present invention will reflect the temperature (Temp1, Temp2) of the respective space. If the asymmetric VIG according to the present invention is positioned with its first glass panel facing the first space, the temperature (T1) of said first glass panel reflects the temperature (Temp1) of the first space, and the temperature (T2) of the second glass panel reflects the temperature (Temp2) of the second space and vice versa.

The thermal stress induced occurs when there is a temperature difference between the first glass panel (1 and T1) and the second glass panels (2 and T2) and increases as the difference between T1 and T2 increases. The temperature difference (ΔΤ) is the absolute difference between the average temperature T1 calculated for the first glass panel (1) and the average temperature T2 calculated for the second glass panel (2). The average glass panel temperature is calculated from numerical simulations known to those skilled in the art. The resulting thermal stress becomes even more problematic - up to the destruction of the VIG, when such an absolute temperature difference between glass panels reaches 20°C and becomes critical when such an absolute temperature difference is above 30°C and reaches 40°C in severe conditions.

In a preferred embodiment, the asymmetric VIG according to the present invention closes the opening of the partition separating the first space with the first temperature Tempi from

- 9 040555 of the second space with the second temperature Temp2, while Tempi is lower than Temp2. The first glass panel of the asymmetric VIG faces the first space so that the thickness Z1 of the first panel (1) is greater than the thickness Z2 of the second panel (2), which faces the first space having a lower temperature (Tempi) than the temperature of the second space (Temp2 ). Indeed, it has been found that in order to maximize the technical advantages of the asymmetric VIG according to the present invention, it is preferable to expose the first glass panel (i) with a thickness Z1 greater than the thickness Z2 of the second glass panel to the cold side, i. the space with the lowest temperature (Tempi).

The present invention also relates to the use of an asymmetric vacuum insulating glazing unit as defined above for closing a partition opening separating a first space with a first temperature Tempi from a second space with a second temperature Temp2, with Tempi lower than Temp2 and with the first glass panel facing to the outer space.

glass panels

The first and second panels of the vacuum insulating glazing unit (VIG) according to the present invention are annealed float glass panels (1, 2). The term glass in this document refers to any type of glass or equivalent transparent material such as mineral glass or organic glass. The mineral glass used can independently be one or more known types of glass such as soda-lime silicate, aluminosilicate or borosilicate, crystalline and polycrystalline glass. The organic glass used may be a polymer, or a rigid thermoplastic or thermoset transparent polymer, or a copolymer, such as a transparent synthetic polycarbonate, polyester or polyvinyl resin. The term float glass panel is to be understood as a glass panel formed by a float process, which is well known in the art. Float glass panels offer lower production cost.

In one embodiment of the present invention, the first glass panel may have a thermal expansion coefficient CTE1 and the second glass panel has a thermal expansion coefficient CTE2, thus the absolute difference between CTE1 and CTE2 may be at most

0.40 10-6/°C (|CTE1-CTE2|<0.40 10-6/°C), preferably at most

0.30 10-6/°C (|CTE1-CTE2|<0.30 10-6/°C), more preferably at most

0.20 10-6/°C (|CTE1-CTE2|<0.20 10-6/°C).

Ideally, the first and second glass panels have the same coefficient of thermal expansion. The term coefficient of thermal expansion (CTE) is a measure of how the size of an object changes with temperature. Specifically, it is a measure of the relative change in volume of a glass panel as the temperature changes per degree at constant pressure.

As is known to those skilled in the art, glass is an elastic material essentially characterized by its Young's modulus, E, and its Poisson ratio, μ. Young's modulus is a measure of elasticity, so larger values indicate glasses that are unlikely to deform under applied stress. Typical Young's modulus values for soda-lime glass, aluminosilicate glass or borosilicate glass compositions range from 60 to 120 GPa (60 GPa<E<120 GPa). In particular, soda-lime glass compositions exhibit a Young's modulus value typically in the range of 69 to 72 GPa (60 GPa<E<72 GPa). Poisson's ratio is a measure of the Poisson effect, which is the phenomenon in which glass tends to expand in directions perpendicular to the direction of contraction. Typical Poisson's ratio values for soda-lime-silicate glass, aluminosilicate glass or borosilicate glass compositions range from 0.18 to 0.30 (0.18<μ<0.30). In particular, soda-lime glass compositions present Poisson's ratio values typically in the range of 0.18 to 0.23 (0.18<μ<0.23).

The term annealed glass panel should be understood to mean a glass panel made by slowly cooling hot glass panels after they are formed to release residual internal stresses generated during manufacture.

Float glass panels may optionally have ground edges. Edge grinding turns sharp edges into smooth edges that are much safer for people who may come into contact with vacuum insulated glazing, in particular the glazing edge.

Preferably, the composition for the first and second asymmetric VIG float glass panels according to the present invention contains the following components in weight percent, expressed relative to the total weight of the glass (cf. A). More preferably, the glass composition (comparison B) is a soda-lime-silicate glass type with a base glass matrix of composition containing the following components in weight percent expressed relative to the total weight of the glass.

Comp. A Comp. IN SiO2 40-78% 60-78% A12OZ 0-18% 0-8 wt.%, preferably 0-6 weight.% B2OS 0-18% 0-4 wt.%, preferably 0-1 weight.% Na2O 0-20% 5-20% by weight, preferably 10-20% by weight CaO 0-15% 0-15 wt.%, preferably 5-15 wt.% MgO 0-10% 0-10 wt.%, preferably 0-8 wt.% K2O 0-10% 0-10 wt% BaO 0-5% 0-5 wt.%, preferably 0-1 wt.%.

Other preferred glass compositions for the first and second glass panels of asymmetric VIG float glass according to the present invention contain the following components in weight percent, expressed relative to the total weight of the glass.

Comp. WITH Comp. D Comp. E 65 < SiO2 < 78 wt% 60 < SiO2 < 78% 65 < SiO2 < 78 wt% 5 < Na2O < 20 wt% 5 < Na2O < 20% 5 <Na2O<20 wt% 0 < K2O < 5 wt.% 0.9 < K2O < 12% 1 < K2O < 8 wt% 1 < A12OZ < 6 wt.%, preferably 3 < A12OZ <5% 4.9 < A12OZ < 8% 1 < A12O3 < 6 wt% 0 < CaO <4.5 wt% 0.4 < CaO < 2% 2 < CaO <10 wt% 4 < MgO < 12 wt% 4 < MgO < 12% 0 < MgO < 8 wt.% (MgO/(MgO+CaO)) > 0.5, preferably 0.88 < [MgO/(MgO+CaO)] < 1. K2O/(K2O+Na2O): 0.1-0.7-

In particular, examples of basic glass matrices for the composition according to the present invention are described in PCT patent applications WO 2015/150207 A1, WO 2015/150403 A1, WO 2016/091672 A1, WO 2016/169823 A1 and WO 2018/001965 A1.

Another preferred glass composition for the first and second asymmetric VIG float glass panels of the present invention comprises the following in weight percent, based on the total weight of the glass:

SiO2 - 60-78%,

A120z - 0-8%,

B2O3 - 0-4%,

Na ₂ O - 5-20%, preferably 10-20 wt.%,

CaO - 0-15%,

- 11 040555

MgO - 0-12%,

K2O - 0-10%,

BaO - 0-5%.

The glass panels may have the same dimensions or different dimensions and thus form a stepped VIG. In a preferred embodiment of the present invention, the first and second float glass panels comprise first and second peripheral edges, respectively, wherein the first peripheral edges are recessed relative to the second peripheral edges, or wherein the second peripheral edges are recessed relative to the first peripheral edges. This configuration increases the strength of the hermetically sealing seal.

In VIG, the first glass panel has an inner surface (12) of the panel and an outer surface (13) of the panel. The second glass panel has an inner surface (22) of the panel and an outer surface (23) of the panel. The first and second inner surfaces of the panels face the inner volume V of the asymmetric VIG. The first and second outer surfaces of the panels face the outside of the VIG.

In some embodiments of the present invention, films such as low emissivity films, solar control films (heat reflective films), antireflection films, antifog films, preferably a heat reflective film or low emissivity film, may be provided on at least one of the interior surfaces (12, 22) of the panel and/or outer surfaces (13, 23) of the panel of the first and/or second float glass panel (1, 2) of the vacuum insulating glazing unit (10). In a preferred embodiment of the present invention, as shown in FIG. 1, the inner surfaces (22) of the second asymmetric VIG float glass panels (2) are provided with a heat reflective film or low-emissivity film (5).

Multi-layer assembly

In one embodiment of the present invention, the outer surface of the first (13) and/or second glass panel (23) may be further laminated to at least one sheet of glass with at least one polymeric intermediate layer, forming a multilayer assembly, to comply with safety regulations. Laminated glass is a type of impact-resistant glass that does not shatter when broken. In the event of failure, it is held in place by a thermoplastic intermediate layer between its two or more layers of glass. The interlayer keeps the layers of glass together even when broken, and its high strength prevents the glass from breaking into large sharp pieces. In a multilayer assembly, at least one sheet of glass preferably has a thickness Zs equal to or greater than 0.5 mm (Zs>0.5 mm). The thickness is measured in a direction perpendicular to plane P. At least one polymeric interlayer is a transparent or translucent polymeric interlayer containing a material selected from the group consisting of ethylene vinyl acetate (EVA), polyisobutylene (PIB), polyvinyl butyral (PVB), polyurethane ( PU), polyvinyl chlorides (PVC), polyesters, copolyesters, polyacetals, cycloolefin polymers (COP), ionomer and/or UV-activated adhesive and others known in the field of laminated glass. Mixed materials using any compatible combination of these materials may also be suitable. Reinforced soundproofing with acoustic laminated glass can also be used in the present invention. In this case, the intermediate polymer layer contains at least one additional acoustic material placed between two polyvinyl butyral films. Glass panels with electrochromic, thermochromic, photochromic or photovoltaic cells are also compatible with the present invention.

Laminated insulating glazing

In another embodiment of the present invention, the present invention is also applicable to any type of glazing unit comprising glass panels (two, three or more) linking insulating or non-insulating internal spaces (also referred to as laminated glazing units), provided that a partial vacuum is applied in at least one of these interior spaces. Therefore, in one embodiment, to improve the mechanical performance of the asymmetric VTG according to the present invention, the third additional glass panel can be connected to at least one of the outer surfaces (13 and/or 23) of the first and second glass panels along the periphery of the VIG by means of a peripheral spacer, also known as a separation window profile, creating an insulating cavity sealed with an edge seal. The specified peripheral spacer frame maintains a specific distance between the third glass panel and at least one of the outer surface of the panel of one of the first and second glass panels. Typically said spacer contains a moisture absorber and typically has a thickness in the range of 6 to 20 mm, preferably 9 to 15 mm. In general, said second internal volume is filled with a predetermined gas selected from the group consisting of air, dry air, argon (Ar), krypton (Kr), xenon (Xe), sulfur hexafluoride (SF6), carbon dioxide, or a combination thereof. The specified target gas is effective to prevent heat exchange

- 12 040555 and/or can be used to reduce sound transmission.

Spacers

As shown in FIG. 1, the vacuum insulating glazing according to the present invention comprises several separate spacers (3), also called struts, located between the first and second glass panels (1, 2) to maintain the internal volume V. According to the present invention, individual spacers are located between the first and second glass panels , maintaining the distance between the first and second glass panels and forming an array with a step λ ranging from 10 to 40 mm (10 mm<λ<40 mm). The array in the present invention is usually a uniform array based on an equilateral triangle, square or hexagon pattern, preferably based on a square pattern.

The individual spacers may have different shapes, such as cylindrical, spherical, thread-like, hourglass-shaped, C-shaped, cruciform, prismatic, etc. Preferably, small posts are used, i.e. posts having a common surface of contact with the glass section formed by their outer circumference equal to or less than 5 mm ² , preferably equal to or less than 3 mm ² , more preferably equal to or less than 1 mm ² . As stated above, such dimensions can offer good mechanical stability while remaining aesthetically unobtrusive.

The individual spacers are typically made of a material having strength capable of withstanding the pressure exerted by the surfaces of the glass panels, capable of withstanding a high temperature process such as annealing and heat curing, and slightly outgassing after the glass panel is manufactured. Such a material is preferably a hard metal material, a quartz glass or a ceramic material, in particular a metal material such as iron, tungsten, nickel, chromium, titanium, molybdenum, carbon steel, chromium steel, nickel steel, stainless steel, nickel-chromium steel, manganese steel, chromium-manganese steel, chromium-molybdenum steel, silicon steel, nichrome, duralumin, etc., or ceramic material such as corundum, alumina, mullite, magnesia, yttrium oxide, aluminum nitride, silicon nitride, etc.

Hermetically sealing seal

As shown in FIG. 1, the internal volume V between the glass panels (1, 2) of the vacuum insulating glazing unit (10) according to the present invention is closed by a hermetically connecting seal (4) placed on the periphery of the glass panels around said internal space. Said hermetically bonding seal is impermeable and solid. In the present description, unless otherwise indicated, the term impermeable means impervious to air or any other gas present in the atmosphere.

The temperature gradient between the interior and exterior spaces actually leads to different thermal deformation of the first and second glass panels according to the present invention. The constraints on each glass panel are even more critical when the seal placed on the periphery of the glass panels is solid. Conversely, such limitations are lower in VIG, in which the peripheral seal allows some deformation.

There are various technologies for making a hermetically bonding seal. The first type of seal (the most common) is a glass solder seal, which has a melting point lower than that of the glass panes of the glazing unit. The use of this type of seal limits the selection of low emissivity layers to those that do not decompose during the thermal cycle required for glass solder applications, i.e. those that can withstand temperatures that can reach 250 ° C. Additionally, since this type of seal based on glass solder can only be deformed to a small extent, it prevents the effects of relative expansion between the glass panel on the inside of the glazing unit and the glass panel on the outside of the glazing unit when these panels are subjected to a large absorption temperature difference. Consequently, sufficiently significant stresses are generated at the periphery of the glazing unit, and this can lead to the destruction of the glass panels of the glazing unit.

The second type of seal is a metal seal, such as a thin metal strip (<500 µm), soldered around the periphery of the glazing unit with a primer coated at least partially with a layer of solderable material, such as soft solder. One significant advantage of this second type of seal over the first type of seal is that it is able to partially deform to partially absorb the relative expansion created between the two glass panels. There are different types of undercoats on glass panel.

Patent application WO 2011/061208 A1 describes one exemplary embodiment of a second type peripheral seal for a vacuum insulating glazing unit. In this embodiment, the seal is a metal strip, for example, made of

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Claims (11)

copper which is soldered by means of a solderable material to an adhesive tape provided on the periphery of the glass panels. Internal volume A vacuum with an absolute pressure of less than 0.1 mbar, preferably less than 0.01 mbar, is created in the internal volume V, formed by the first and second glass panels and a set of separate spacers, and is closed by a hermetically connecting seal inside the asymmetric VIG of the present invention. The internal volume of the asymmetric VTG according to the present invention may contain gas, for example, but not exclusively, air, dry air, argon (Ar), krypton (Kr), xenon (Xe), sulfur hexafluoride (SF 6) or combinations thereof. The transfer of energy through an insulating block having this conventional structure is reduced due to the presence of gas in the interior relative to the single glass glass panel. Any gas can also be evacuated from the internal volume, thereby creating a vacuum glazing unit. The transfer of energy through an insulating vacuum insulated glazing unit is greatly reduced by the vacuum. To create a vacuum in the interior of the glazing unit, a hollow glass tube is usually provided on the main surface of one of the glass panels to provide communication between the interior and the exterior. Thus, a partial vacuum is generated in the interior by pumping out the gases in the interior with a pump connected to the outer end of the glass tube. To maintain a predetermined vacuum level in the vacuum insulating glazing unit for a certain time, a getter can be used in the glazing unit. In particular, the inner surfaces of the glass panels constituting the glazing unit may release, over time, the gases previously absorbed by the glass, thereby increasing the internal pressure in the vacuum insulating glazing unit and thus reducing the vacuum performance. In general, such a getter consists of alloys of zirconium, vanadium, iron, cobalt, aluminum, etc. and is applied in the form of a thin layer (a few microns thick) or made in the form of a bar placed between the glass panels of the glazing unit so that it does not visible (for example, hidden by outer enamel or part of a peripheral impermeable seal). The getter forms a passivation layer on its surface at room temperature, and therefore it must be heated to remove the passivation layer and thus activate the getter properties of its alloy. The getter is considered to be heat activated. Reference position Component 10 Vacuum insulating glazing 1 First glass panel 12 Inner surface of the first glass panel 13 The outer surface of the first glass panel 2 Second glass panel 22 Inner surface of the second glass panel 23 The outer surface of the second glass panel 3 Separate spacer 4 Hermetically sealing seal 5 Thermal reflective film or low-emissivity film V Internal volume CLAIM 1. Vacuum insulating block (10) glazing, passing along the plane P, defined by the longitudinal axis X and the vertical axis Z; having a width W measured along the longitudinal axis X and a length L measured along the vertical axis Z, and containing: a) a first glass panel (1) having a thickness Z1 and a second glass panel (2) having a thickness Z2, the thicknesses being measured in the direction perpendicular to the plane P, with Z1 being greater than Z2 (Z1>Z2), and wherein the first glass panel and the second glass panel are annealed float glass panels; b) a set of separate spacers (3) located between the first and second glass panels, - 14 040555 maintaining the distance between the first and second glass panels and forming an array with a step λ; c) a hermetically connecting seal (4) sealing the gap between the first and second glass panels along their perimeter; d) an internal volume V formed by the first and second glass panels and a set of separate spacers and closed by a hermetically connecting seal, and at the same time a vacuum with an absolute pressure of less than 0.1 mbar is created in it, characterized in that the length L of the vacuum insulating glazing unit is equal to or greater than 800 mm (L>800 mm) and the width W of the vacuum insulating glazing unit is equal to or greater than 500 mm (W>500 mm); in this case, the thickness ratio Z1/Z2, i.e. the thickness Z1 of the first glass panel to the thickness Z2 of the second glass panel, equal to or greater than 1.10 (Z1/Z2>1.10); wherein the step λ is in the range from 10 to 40 mm (10 mm<λ<40 mm); and wherein the thickness Z2 of the second glass panel is equal to or greater than 4 mm (Z2>4 mm) and equal to or greater than (λ-15 mm)/5(Z2>(λ-15 mm)/5). 2. Vacuum insulating glazing unit according to claim 1, characterized in that the thickness ratio Z1/Z2 is equal to or greater than 1.20 (Z1/Z2>1.20), preferably equal to or greater than 1.30 (Z1/Z2>1, 30), more preferably equal to or greater than 1.55 (Z1/Z2>1.55), even more preferably in the range of 1.60 to 6.00 (1.60<Z1/Z2<6.00), in ideally from 2.00 to 4.00 (2.00<Z1/Z2<4.00). 3. Vacuum insulating glazing unit according to any one of the preceding claims, characterized in that the pitch λ is in the range of 15 to 35 mm (15 mm<λ<35 mm), preferably 20 to 30 mm (20 mm<λ<30 mm) ). 4. The vacuum insulating glazing unit according to any one of the preceding claims, characterized in that the length L of the vacuum insulating glazing unit is equal to or greater than 1000 mm (L>1000 mm), preferably equal to or greater than 1200 mm (L>1200 mm). 5. The vacuum insulating glazing unit according to any one of the preceding claims, characterized in that the width W of the vacuum insulating glazing unit is equal to or greater than 600 mm (W>600 mm), preferably equal to or greater than 800 mm (W>800 mm), more preferably equal to or greater than 1000 mm (W>1000 mm), even more preferably equal to or greater than 1200 mm (W>1200 mm). 6. Vacuum insulating glazing unit according to any one of the preceding claims, characterized in that at least one of the first and second glass panels, preferably the second glass panel, is made of soda lime silicate glass, aluminosilicate glass or borosilicate glass. 7. Vacuum insulating glazing unit according to claim 6, characterized in that the composition of the second glass panel contains the following in weight percent, expressed relative to the total weight of the glass: SiO ₂ - 60-78%, Al ₂ O ₃ - 0-8 wt.%, B2O3 - 0-4 wt.%, Na ₂ O - 5-20 wt.%, preferably 10-20 wt.%, CaO - 0-15 wt.%, MgO - 0-12 wt.%, K2O - 0-10%, BaO - 0-5%. 8. Vacuum insulating glazing unit according to any of the preceding claims, characterized in that the first glass panel and the second glass panel have outer surfaces (13) and (23) of the panel, respectively, while the outer surfaces (13, 23) of the panels face the outer part vacuum insulating glazing unit, and wherein at least one of the outer surfaces (13 and 23) of the panels is laminated to at least one sheet of glass by at least one intermediate polymer layer, forming a multilayer assembly. 9. Vacuum insulating glazing unit according to any of the preceding claims, characterized in that the first and second glass panels have an inner surface (12, 22) of the panel, respectively, and an outer surface (13, 23) of the panel, respectively, while the inner surfaces of the panel face the inner volume V, and at the same time at least one of the inner surfaces (12, 22) and/or outer surfaces (13, 23) is provided with at least a film that reflects heat rays or a low-emissivity film (5). 10. The vacuum insulating glazing unit according to any one of the preceding claims, characterized in that at least one of the outer surfaces (13 and/or 23) of the panels of the first and second panes is attached to the third glass panel along the periphery of the vacuum insulating glazing unit by means of a peripheral spacer frame. , creating an insulating cavity sealed by a peripheral edge seal. 11. Vacuum insulating glazing unit according to any of the preceding claims, characterized -