GB2580172A

GB2580172A - Vacuum insulated glazing unit

Info

Publication number: GB2580172A
Application number: GB1821154.0A
Authority: GB
Inventors: Robert Nichol Gary
Original assignee: Pilkington Group Ltd
Current assignee: Pilkington Group Ltd
Priority date: 2018-12-21
Filing date: 2018-12-21
Publication date: 2020-07-15
Anticipated expiration: 2038-12-21
Also published as: GB2580172B; GB201821154D0

Abstract

The unit 1 comprises a first sheet 2 of glazing material with a first face 3 and a second face 4 and a second sheet 5 of glazing material with a first face 6 and second face 7. The sheets are arranged in a spaced apart, first face to first face arrangement. The unit further comprises a hermetic seal 9 located between the first and second sheet of glazing material to form a cavity 8 between the first faces of the glazing sheets with the unit further comprising one or more spacers 10 located between the first and second glazing sheet material wherein the hermetic seal comprises at least 50% by weight silicon oxide. The first and/or second sheets may comprise of glass or may be comprised of thermally toughened glass. The unit may further comprise an evacuation port (15, fig 3). Also disclosed is a method for manufacturing said vacuum insulated glazing unit.

Description

VACUUM INSULATED GLAZING UNIT

The present invention relates to a vacuum insulated glazing unit. More particularly, the present invention relates to a vacuum insulated glazing unit suitable for use in an architectural glazing, and a method for manufacturing same.

Vacuum insulated glazings (VIGs) have been known for some time and are often used in architectural glazings to provide an insulating glazing unit (IGU) of comparable insulating effectiveness, but of decreased thickness, compared to conventional gas filled IGUs. An example of a VIG is available under the trademark, Pilkington SpaciaTM, from NSG. VIGs are commonly used to replace single pane glazings to provide increased insulating effectiveness while maintaining architectural character of the surrounding frame and/or building.

VIGs commonly comprise two sheets of glazing material arranged in a spaced apart, face-to-face arrangement, to provide a cavity between the two sheets of glazing material. A VIG may be provided with a frame for installation in a door or window. The cavity is commonly evacuated to a pressure below 10-3 mbar and must maintain this pressure over the lifetime of the vacuum insulated glazing unit, which is typically between 15 and 20 years. In addition, VIGs are commonly provided with a hermetic seal for maintaining the vacuum within the cavity over the lifetime of the vacuum insulated glazing unit. The hermetic seal is commonly provided between, and at the periphery of, the sheets of glazing material. Ingress of gas into an evacuated unit (commonly known as a "loss of vacuum") is associated with a large reduction in the insulating properties of the vacuum insulated glazing unit, as this gas provides a method of heat transfer across the glazing unit. Other methods of heat transfer across a VIG include thermal conduction through spacers provided for maintaining the cavity, thermal conduction through hermetic and/or edge seals, and radiative heat transfer through the sheets of glazing material, for example by infra-red (IR) radiation.

For example, US 6,210,763 B1 discloses a double-glazing unit comprising: a pair of glass sheets; a plurality of spacers disposed between opposed sheet faces of the glass sheets and separated by a predetermined pitch; and a sealing member interposed between the glass sheets and along the entire peripheries thereof, with a space formed between the glass sheets being sealed in a vacuum condition. The sealing member may be made of a low melting point glass (for example solder glass).

Similarly, US 5902652 A discloses a thermally insulating glass panel, comprising: two sheets of glass, each having a continuous peripheral edge and a central region within said peripheral edge. An edge seal of solder glass connects said glass sheets in a spaced facing relationship, by extending between the respective peripheral edges of the glass sheets. The glass sheets and said edge seal enclose a space of reduced pressure in comparison to ambient atmospheric pressure. The solder glass is deposited as a liquid slurry, a powder, or a rod. When the above construction is heated and the solder glass melts, same flows between the two glass sheets by the action of capillary forces.

While VIGs comprising solder glass seals, such as those disclosed in US 6,210,763 B1 and US 5902652 A are suitable for many functions, these arrangements are not without drawbacks. For example, solder glass seals, under certain conditions, can be prone to temperature related stress failures, due to a mismatch between the expansion coefficient of the solder glass and the glass panes. Additionally, solder glass seals may, under certain conditions, suffer from salt spray corrosion, leading to a loss of vacuum within the vacuum insulated glazing.

Further, solder glass seals often contain lead, and/or other toxic compounds such as arsenic or vanadium oxides, as discussed by Frieser in Electrocomponent Science and Technology, 1975, Vol. 2, pp. 163-199. Consequently, the toxicity of solder glasses may make VIGs comprising such a seal unsuitable for use, and also require costly precautions to be taken during the manufacture of same. For example, solder glass is often provided as a powder, requiring containment to prevent inhalation during production.

Additionally, VIGs comprising solder glass seals may not be completely and/or lastingly sealed during manufacture, leading to defects. For example, where the solder glass is provided as a liquid slurry, care is required to ensure that the evaporation of the slurry liquid does not disturb the hermetic seal. Also, where solder glass is provided as a rod, a slurry, or a powder, the solder glass may not flow sufficiently into the cavity to provide a homogenous seal capable of preventing loss of vacuum throughout the lifetime of the VIG.

Lead-free solder glass compositions are sometimes used for preparing VIG solder glass seals. For example, US 20150218032 Al discloses a method of making a vacuum insulating glass window unit comprising first and second glass substrates, each substrate having first and second major surfaces. The method is complicated and involves applying a first lead-free frit material around perimeter edges of each first major surface of the first and second substrates, and heat treating the first and second substrates with the first frit material applied thereon to a first peak temperature. Following said heat treatment, a second lead-free frit material is applied on the first and/or second substrate(s) such that, for each substrate on which the second frit material is applied, the second frit material at least partially overlaps the first frit material on the respective substrate around peripheral edges thereof, the first and second frit materials having different compositions. However, applying multiple VIG sealing materials in multiple stages is labour intensive and generally increases the cost of a VIG unit.

While lead-free solder glass compositions aim to be of reduced toxicity compared to leaded solder glass compositions, such compositions may contain other toxic compounds. In addition, lead-free solder glass compositions do not address the problem that solder glass seals may not be completely and/or lastingly sealed during manufacture, leading to defects.

Additionally, lead-free solder glass compositions typically have melting temperatures close to or above the softening point of VIG glass substrates. As such, the use of lead-free solder glass compositions with toughened (that is, thermally tempered or heat treated) glass panes is associated with the loss of temper strength of the glass pane, as the entire VIG unit must be heated at a temperature at or above the melting temperature for a significant length of time to cause the solder glass to flow and form a hermetic seal between the glass panes. Consequently, other methods of heating the solder glass have been investigated.

For example, US 20100275654 Al discloses a method of making a vacuum insulating glass (VIG) unit, the method comprising: providing first and second substantially parallel spaced-apart glass substrates, the first and second substrates each including one or more edge portions to be sealed. A glass frit is provided at least partially between the first and second glass substrates for sealing said one or more edge portions, and then infrared energy is applied from one or more infrared energy sources towards the one or more edge portions to be sealed in forming an edge seal of the VIG unit. The glass frit has a glass redox (Fe0/Fe703) that is higher than a glass redox (Fe0/Fe203) of the first and second substrates. While heating using infrared energy sources maintains temper strength across the bulk glass pane, a loss of temper strength will be caused in and/or near the irradiated edge portions. As VIGs are commonly secured to frames at the edge portions, this loss of temper strength may cause a significant weakness in the VIG unit.

Another method of sealing VIGs includes the use of metal foils and/or metal solders, as described by Weinlacier et al., 7th International Vacuum Insulation Symposium, 2005. However, metal seals are prone to corrosion over time, which may lead to failure of the seal, resulting in a loss of vacuum and an associated significant reduction in the insulating properties of the VIG. In addition, the seal formed between metals foils and/or metal solders and glass is often weak, requiring reinforcement with tape or other adhesive means. Furthermore, due to the differing thermal expansion coefficients of glass and metal, it is not possible to form a seal with sufficient leak tightness.

A further method of sealing VIGs involves the use of organic materials, such as polymers. However, such organic materials are prone to "out-gassing", whereby volatile organic compounds are evaporated or sublimated from the organic material. This "out-gassing" introduces gas into the evacuated cavity, and as such increases the number of gas molecules capable of transferring heat across the cavity. Such volatile organic compounds also have the potential to corrode upon contact, and therefore can lead to marring of the VIG's appearance, or a loss of the vacuum contained in the VIG, reducing the insulating effectiveness of same.

VIGs are often provided with one or more spacers for maintaining the cavity between the sheets of glazing material. Often these spacers are metal or plastic. However, the use of such spacers often requires laborious placing to ensure an even spacing across the sheets of glazing material. An alternative method of producing spacers is proposed by US 9650292 B2, which discloses a method of forming a glass article comprising a plurality of glass bumps, wherein the glass bumps are formed in the glass article by laser radiation. However, such a method relies on a laser-irradiation process that is expensive and difficult to use in a manufacturing setting.

It is an object of the present invention to provide a vacuum insulated glazing unit comprising an alternative hermetic seal that overcomes the drawbacks of currently available seals. In addition, it is an object of the present invention to provide a vacuum insulated glazing unit comprising an alternative spacer that overcomes the drawbacks of currently available spacers. Also, it is an aim of the present invention to produce an improved vacuum insulated glazing unit in a cost effective manner and at low temperatures while meeting the demanding performance requirements of modern glazing units.

Therefore, according to a first embodiment of a first aspect of the present invention there is provided a vacuum insulated glazing unit, comprising: (i) a first sheet of glazing material with a first face and a second face; (ii) a second sheet of glazing material with a first face and a second face, arranged in a spaced apart, first face to first face arrangement with the first sheet of glazing material; (iii) a hermetic seal located between the first sheet of glazing material and the second sheet of glazing material to form a cavity between the first faces of the first and second sheets of glazing material; and (iv) one or more spacers located between the first sheet of glazing material and the second sheet of glazing material, wherein the hermetic seal comprises at least 50% by weight silicon oxide.

According to a second embodiment of a first aspect of the present invention, there is provided a vacuum insulated glazing unit, comprising: (i) a first sheet of glazing material with a first face and a second face; (ii) a second sheet of glazing material with a first face and a second face, arranged in a spaced apart, first face to first face arrangement with the first sheet of glazing material; (iii) a hermetic seal located between the first sheet of glazing material and the second sheet of glazing material to provide a cavity between the first faces of the first and second sheets of glazing material; and (iv) one or more spacers located between the first sheet of glazing material and the second sheet of glazing material, wherein the one or more spacers comprise at least 50% by weight silicon oxide.

Preferably, the hermetic seal and the one or more spacers each comprise at least 50% by weight silicon oxide.

Preferably, in relation to the present invention, the hermetic seal and/or the one or more spacers comprise at least 70% by weight silicon oxide. More preferably the hermetic seal and/or one or more spacers comprises at least 90% by weight silicon oxide. Even more preferably the hermetic seal and/or one or more spacers comprises at least 95% by weight silicon oxide.

A hermetic seal comprising at least 50% by weight silicon oxide may provide reduced heat transfer across the vacuum insulated glazing unit via thermal conduction through the seal. A hermetic seal comprising at least 50% by weight silicon oxide may further provide structural integrity to the VIG, reducing the number of spacers and/or their size required to maintain the cavity. For some small vacuum insulated glazing units, a hermetic seal comprising at least 50% percentage by weight silicon oxide may obviate the need for spacers altogether. A hermetic seal comprising at least 50% by weight silicon oxide may provide a seal with reduced visibility.

Preferably, the hermetic seal does not comprise soda-lime silica glass, borosilicate glass, aluminosilicate glass, or alkali aluminosilicate glass.

Preferably, the hermetic seal extends into the cavity from an edge of the vacuum insulated glazing unit by a distance 'd'. Preferably, distance Id' is from 2 mm to 10 mm. More preferably 'd' is from 3 mm to 7 mm.

Preferably, the cavity comprises a pressure of 10-3 mbar or less. Such a pressure may provide beneficial insulating properties.

In relation to the present invention the first and/or second sheets of glazing material preferably comprise glass.

Preferably the first and/or second sheets of glazing material comprise heat treated glass or thermally strengthened glass. Alternatively, the first and/or second sheets of glazing material may comprise chemically strengthened glass. Heat treated, thermally strengthened and chemically strengthened glasses may provide improved impact resistance to the vacuum insulated glazing unit.

Preferably, the first and/or second sheets of glazing material comprise float glass. Float glass offers the advantage of being more cost-effective to produce than other types of glass. Preferably the first and/or second sheets of glazing material comprise soda-lime silica glass. A vacuum insulated glazing unit comprising a sheet of glazing material comprising soda-lime silica glass is preferable, as the coefficient of thermal expansion of soda-lime silica glass is similar to the coefficient of thermal expansion of a hermetic seal comprising at least 50% by weight silicon oxide. This matching of coefficient of thermal expansion also offers the advantage of a reduced risk of breakage of the sheet of glazing material, or the hermetic seal, or the join there between, by thermal expansion and contraction. The reduced risk of breakage due to thermal expansion and contraction may prevent a loss of vacuum, thereby maintaining the beneficial insulating properties of the vacuum insulated glazing unit throughout the lifetime of the vacuum insulated glazing unit.

Furthermore, soda-lime silica glass is preferable as a glazing material as it is generally more cost-effective to produce than alternative glass compositions.

Preferably the thickness of the first and/or the second sheet of glazing material is from 1.5 mm to 6 mm. More preferably, the thickness of the first and/or the second sheet of glazing material is from 3 mm to 5 mm. A thickness of greater than 6 mm for the first and/or the second sheet of glazing material may be associated with a thicker vacuum insulated glazing unit, which may be unsuitable for use. A thickness of less than 1.5 mm for the first and/or the second sheet of glazing material may be associated with a loss of unit rigidity, requiring more spacers and/or larger spacers to maintain the vacuum insulated glazing unit cavity.

Preferably the distance between the first face of the first sheet of glazing material and the first face of the second sheet of glazing material is from 50 pm to 500 pm. More preferably the distance between the first face of the first sheet of glazing material and the first face of the second sheet of glazing material is from 100 pm to 300 pm. A distance greater than 500 pm between the first face of the first sheet of glazing material and the first face of the second sheet of glazing material may make achieving the desired pressure within the cavity more difficult. A distance less than 50 pm between the first face of the first sheet of glazing material and the first face of the second sheet of glazing material may allow thermal conduction across the vacuum insulated glazing unit arising from residual gas within the cavity.

In the vacuum insulated glazing unit according to the present invention, the hermetic seal preferably comprises at most 1% by weight lead. Preferably, the hermetic seal is substantially free from lead.

Preferably, the hermetic seal comprises at most 1% by weight of each of vanadium, zinc, copper, nickel, manganese, tellurium, arsenic, or a combination. Hermetic seals that have a higher composition of metals may be toxic, and/or susceptible to corrosion, and are therefore less preferred.

Also in relation to the vacuum insulated glazing unit according to the present invention, it is preferred that one or both first faces of the first and second sheets of glazing material comprise a low emissivity coating.

Preferably the low emissivity coating comprises a transparent conductive oxide, for example fluorine doped tin oxide. Alternatively, the low emissivity coating may comprise a metallic film, for example silver.

In the vacuum insulated glazing unit according to the present invention the cavity comprises one or more spacers. Such spacers may be provided to maintain the cavity between the sheets of glazing material.

One or more of the spacers that comprise silicon dioxide may be substantially transparent, thereby improving the transmission of light through the vacuum insulated glazing unit and improving the appearance of the vacuum insulated glazing unit. The coefficient of thermal expansion for a glazing sheet comprising glass, especially soda-lime silica glass, and one or more of the spacers comprising at least 50% by weight silicon oxide may be closely matched. This matching of coefficient of thermal expansion provides the effect of a reduced risk of breakage of the sheet of glazing material, or the spacers, or a join formed therebetween, by thermal expansion and contraction. The reduced risk of breakage due to thermal expansion and contraction prevents a loss of vacuum, maintaining the beneficial insulating properties of the vacuum insulated glazing unit throughout the lifetime of the vacuum insulated glazing unit.

Alternatively, the spacers may comprise metal, or a polymeric material. Preferably the spacers do not comprise soda-lime glass, borosilicate glass, aluminosilicate glass, and/or alkali aluminosilicate glass.

The spacers are preferably arranged within the cavity to have a predetermined height between the sheets of glazing material, a predetermined diameter, and a predetermined distance between one another.

Preferably, the predetermined distance between a first spacer and a second spacer, also known as the spacer pitch, in combination with the size of the spacers, is sufficient to maintain the cavity of the vacuum insulated glazing unit. Preferably the spacer pitch is from 5 mm to 100 mm. More preferably the spacer pitch is from 10 mm to 80 mm. Even more preferably the spacer pitch is from 30 mm to 60 mm. A pitch greater than 100 mm may reduce the ability of the spacers to maintain the cavity. A pitch less than 5 mm may increase heat conduction through the spacers, reducing the insulating properties of the vacuum insulated glazing unit, and reduce the transmission of light through, and/or impair the appearance of, the vacuum insulated glazing unit.

Preferably, the spacer height is from 50 pm to 500 pm. More preferably the spacer height is from 100 pm to 300 pm. The spacer height is related to the distance between the first sheet of glazing material and the second sheet of glazing material. A greater spacer height may make achieving the desired pressure within the cavity more difficult. A lesser spacer height may allow thermal conduction across the vacuum insulated glazing unit by residual gas within the cavity.

Preferably, the spacer diameter is from 0.3 mm to 2 mm. A spacer of diameter greater than 2 mm may increase heat conduction through the spacer, reducing the insulating properties of the vacuum insulated glazing unit. In addition, a spacer of diameter greater than 2 mm may reduce the transmission of light through, and/or impair the appearance of, the vacuum insulated glazing unit. A spacer diameter of less than 0.3 mm may be difficult to manufacture and/or may lack the strength required to maintain the cavity when evacuated.

Also in relation to the present invention, the cavity of the vacuum insulated glazing unit may comprise a peripheral region and an internal region, wherein the peripheral region and the internal region are preferably separated by a barrier.

Preferably, the peripheral region comprises the hermetic seal. Preferably the internal region comprises the one or more spacers. The barrier may comprise metal. However, it is preferred that in relation to the present invention that the preferably barrier comprises silicon oxide.

Preferably, the barrier comprises at least 70% by weight silicon oxide. Even more preferably, the barrier comprises at least 90% by weight silicon oxide. Most preferably, the barrier comprises at least 95% by weight silicon oxide.

A barrier that comprises silicon oxide may be less visible to an observer looking through the vacuum insulated glazing unit than alternative barriers, improving the transmission of light through the vacuum insulated glazing unit and improving the appearance of the vacuum insulated glazing unit. The coefficient of thermal expansion for a glazing sheet comprising glass, especially soda-lime silica float glass, and a barrier comprising silicon oxide may be closely matched. This matching of coefficient of thermal expansion provides the effect of a reduced risk of breakage of the sheet of glazing material, the barrier, or a join formed therebetween, by thermal expansion and contraction. The reduced risk of breakage due to thermal expansion and contraction prevents a loss of vacuum, maintaining the beneficial insulating properties of the vacuum insulated glazing unit throughout the lifetime of the vacuum insulated glazing unit. Preferably, the barrier is a printed barrier.

The vacuum insulated glazing unit may be provided with an evacuation port, for evacuating the cavity. The evacuation port may be provided at the periphery of the vacuum insulated glazing unit, through the hermetic seal. Alternatively, the evacuation port may be provided through a sheet of glazing material. In either case, the evacuation port is preferably sufficiently sealed to maintain the vacuum within the cavity over the lifetime of the vacuum insulated glazing unit. Alternatively, the vacuum insulated glazing unit may be provided without an evacuation port, in cases where the vacuum insulated glazing unit is manufactured under vacuum conditions.

According to a first embodiment of a second aspect of the present invention there is provided a method for manufacturing a vacuum insulated glazing unit according to the first embodiment of the first aspect of the present invention comprising the steps of: (i) providing a first sheet of glazing material with a first face; (ii) providing a second sheet of glazing material with a first face; (iii) arranging the second sheet of glazing material and the first sheet of glazing material in a spaced apart, first face to first face configuration; (iv) introducing a silicon oxide precursor between the first sheet of glazing material and the second sheet of glazing material and/or applying a silicon oxide precursor to the first face of the first sheet of glazing material and/or applying a silicon oxide precursor to the first face of the second sheet of glazing material; and (v) curing the silicon oxide precursor to form a hermetic seal comprising silicon oxide, wherein the first faces of the first and second sheets of glazing material and the hermetic seal form a cavity.

According to a second embodiment of the second aspect of the present invention there is provided a method for manufacturing a vacuum insulated glazing unit according to the second embodiment of the first aspect of the present invention comprising the steps of: (i) providing a first sheet of glazing material with a first face; (ii) providing a second sheet of glazing material with a first face; (iii) arranging the second sheet of glazing material and the first sheet of glazing material in a spaced apart, first face to first face configuration; (iv) introducing a silicon oxide precursor between the first sheet of glazing material and the second sheet of glazing material and/or applying a silicon oxide precursor to the first face of the first sheet of glazing material and/or applying a silicon oxide precursor to the first face of the second sheet of glazing material; (v) curing the silicon oxide precursor to form one or more spacers comprising silicon oxide; and (vi) introducing a hermetic seal between the first faces of the first and second sheets of glazing material, wherein the first faces of the first and second sheets of glazing material and the hermetic seal form a cavity.

Preferably, the step of introducing a silicon oxide precursor between the first sheet of glazing material and the second sheet of glazing material is after the step of arranging the second sheet of glazing material and the first sheet of glazing material.

Alternatively, the step of applying a silicon oxide precursor to the first face of the first sheet of glazing material may be prior to the step of arranging the second sheet of glazing material and first sheet of glazing material.

Alternatively, the step of applying a silicon oxide precursor to the first face of the second sheet of glazing material may be prior to the step of arranging the second sheet of glazing material and the first sheet of glazing material.

Preferably the cavity pressure is reduced to less than or equal to 10-3 mbar. More preferably the cavity pressure is reduced to less than or equal to 10-4 mbar.

A cavity pressure greater than 10-3 mbar is associated with an increase in thermal conduction by residual gas within the cavity, reducing the insulating properties of the vacuum insulated glazing unit.

Also according to either the first or second embodiments of the method according to the second aspect of the present invention, the silicon oxide precursor preferably comprises a polysilazane material or an alkali-silicate material. More preferably, the silicon oxide precursor comprises perhydropolysilazane. Alternatively, the silicon oxide precursor preferably comprises tetraethyl orthosilicate (TEOS).

Also, in relation to the present invention the silicon oxide precursor is preferably provided as a solution. Preferably, the solution comprises at least 70% by weight polysilazane. More preferably the solution comprises at least 90% by weight polysilazane. Even more preferably the solution comprises at least 95% by weight polysilazane. Most preferably the solution comprises at least 99% by weight polysilazane.

Preferably the spacers are printed spacers. Providing spacers using a printing method may allow easier and faster application of VIG spacers compared to traditional methods, such as the placement of a matrix of solid metal spacers. Preferably, the spacers are printed using a digital ink-jet printing method. Preferably, the spacers are formed using a silicon oxide precursor.

Preferably, the spacers are not provided using a laser-irradiation growth formation method.

Also in relation to the method according to the present invention, during the step of curing the silicon oxide precursor to form a hermetic seal and/or the one or more spacers comprising silicon oxide, the temperature of the first and/or second sheets of glazing material are preferably maintained at a temperature from -50 °C to 450 °C.

Preferably, during the step of curing the silicon oxide precursor to form a hermetic seal and/or the one or more spacers comprising silicon oxide the temperature of the first and/or second sheets of glazing material is maintained within a range of from 10 °C to 400 °C. More preferably the temperature of the first and/or second sheets of glazing material is maintained within a range of from 50 °C to 300 °C. Most preferably the temperature of the first and/or second sheets of glazing material is maintained within a range of from 100 °C to 250 °C.

Preferably, during the step of curing the silicon oxide precursor to form a hermetic seal and/or the one or more spacers comprising silicon oxide, the silicon oxide precursor is heated to a temperature from 150 °C to 250 °C.

Preferably, during the step of curing the silicon oxide precursor to form a hermetic seal and/or the one or more spacers comprising silicon oxide the silicon precursor is heated for 1 to 5 hours. More preferably during the step of curing the silicon oxide precursor to form a hermetic seal and/or the one or more spacers comprising silicon oxide the silicon precursor is heated for 2 to 4 hours.

In addition, in relation to the method for manufacturing a vacuum insulated glazing unit according to the present invention, it is preferred that the step of curing the silicon oxide precursor to form a hermetic seal and/or the one or spacers comprising silicon oxide comprises a step of illuminating the silicon oxide precursor with UV light.

Also, the method according to the present invention preferably further comprises providing a barrier prior to the step of introducing the silicon oxide.

Preferably the barrier comprises a printed barrier. Preferably the barrier is printed using a digital ink-jet printing method. Preferably the barrier is printed using a silicon oxide precursor.

According to a third aspect of the present invention there is provided the use of a vacuum insulated glazing according to the first aspects of the present invention or manufactured by the method according to the second aspects of the present invention in an architectural glazing unit.

In this regard, all preferences described above in relation to the first and second aspects of the present invention also apply in relation to the third aspect of the present invention, and vice versa.

Embodiments of the present invention will now be described by way of example only with reference to the following accompanying drawings and specific examples in which: Figure 1 illustrates a schematic cross-sectional view of a vacuum insulated glazing unit according to a first embodiment of the present invention; Figure 2 illustrates a schematic cross-sectional view of a vacuum insulated glazing unit according to a second embodiment of the present invention; Figure 3 illustrates a schematic plan view of the vacuum insulated glazing unit according to the second embodiment of the present invention depicted in Figure 2 along line A-A; and Figure 4 is an image of a vacuum insulated glazing unit prepared by way of example according to the first embodiment of the present invention as depicted in Figure 1.

Referring to each of the figures in detail, Figure 1 illustrates a schematic cross-sectional view of a vacuum insulated glazing unit 1 according to a first embodiment of the present invention. The vacuum insulated glazing unit 1 comprises a first sheet of glazing material 2 with a first face 3 and a second face 4, and a second sheet of glazing material 5 with a first face 6 and a second face 7. The thicknesses and compositions of the first sheet of glazing material 2 and the second sheet of glazing material 5 may be the same, or different. However, the thicknesses and compositions of the first and second sheets of glazing material are preferably sufficient to provide rigidity to the vacuum insulated glazing unit 1 in use. A suitable composition is, for example, provided by soda-lime silica float glass. Suitable thicknesses of sheets of glazing materials range, for example, from 1.5 mm to 6 mm.

A hermetic seal 9 is present between the first sheet of glazing material 2 and the second sheet of glazing material 5 and is preferably at the periphery of the sheets of glazing material.

A cavity 8 is formed between the hermetic seal 9 and the first faces 3 and 6 of the first sheet of glazing material 2 and the second sheet of glazing material 5 respectively. The cavity 8 is an evacuated cavity, for providing insulating character to the vacuum insulated glazing unit 1. The distance between the first sheet of glazing material 2 and the second sheet of glazing material 5, also known as the inter-pane distance, is preferably sufficient to ensure that any residual gas within the cavity 8 does not reduce the insulating effectiveness of the vacuum insulated glazing unit 1. A suitable inter-pane distance may be, for example, 200 pm.

The hermetic seal 9 maintains the vacuum within the cavity over the lifetime of the vacuum insulated glazing unit 1. The hermetic seal 9 preferably comprises silicon oxide in this embodiment. In addition, the hermetic seal 9 preferably extends into the cavity 8 by a distance "d" measured from an edge 11 of the vacuum insulated glazing unit 1. The distance "d" is referred to herein as the ingression distance. The hermetic seal 9 may be substantially level with the edge 11 as indicated by Figure 1. Alternatively, the hermetic seal 9 may bet set back from edge 11 to provide an edge slot (not shown). This may be accomplished, for example, by removing a portion of the hermetic seal 9 following curing.

The vacuum insulated glazing unit 1 as depicted in Figure 1 further comprises one or more spacers 10, to maintain the cavity 8. The spacers are preferably sufficient to maintain the inter-pane distance between the sheets of glazing material. The number of spacers required to maintain the cavity is not fixed, and preferably depends on the thickness and rigidity of the sheets of glazing material, the strength of the vacuum within the cavity, the distance between the sheets of glazing material, and the compressive strength of the hermetic seal itself.

In this first embodiment the vacuum insulated glazing unit 1 comprises a hermetic seal 9 comprising at least 50% by weight silicon oxide. Alternatively, the vacuum insulated glazing unit 1 comprises one or more spacers 10 comprising at least 50% by weight silicon oxide. Alternatively, the vacuum insulated glazing unit 1 comprises a hermetic seal 9 comprising at least 50% by weight silicon oxide and one or more spacers 10 comprising at least 50% by weight silicon oxide. As such, the vacuum insulated glazing unit 1 comprises a hermetic seal 9 comprising at least 50% by weight silicon oxide and/or one or more spacers 10 comprising at least 50% by weight silicon oxide.

Figure 2 illustrates a schematic cross-sectional view of a vacuum insulated glazing unit 20 according to a second embodiment of the present invention. The vacuum insulated glazing unit 20 comprises a first sheet of glazing material 2 with a first face 3 and a second face 4, and a second sheet of glazing material 5 with a first face 6 and a second face 7.

A hermetic seal 9 is provided between the first sheet of glazing material 2 and the second sheet of glazing material 5. The hermetic seal 9 preferably comprises silicon oxide in this embodiment.

A cavity 8 is located between the hermetic seal 9 and the first faces 3 and 6 of the first sheet of glazing material 2 and the second sheet of glazing material 5 respectively. The cavity 8 is an evacuated cavity for providing insulating character to the vacuum insulated glazing unit 20.

The vacuum insulated glazing unit 20 further comprises spacers 10, to maintain the cavity 8. The cavity 8 further comprises peripheral region 13 and an internal region 14. The peripheral region 13 and the internal region 14 are separated by a barrier 12. Preferably the internal region 14 comprises a vacuum, and the peripheral region comprises the hermetic seal 9.

The barrier 12 preferably comprises a non-porous material that does not "out-gas" under vacuum. Preferably, the barrier 12 comprises silicon oxide. Alternatively, the barrier 12 comprises metal.

In addition, preferably the barrier 12 is of sufficient rigidity to maintain the cavity 8 during ingress of a silicon oxide precursor. Preferably the barrier 12 allows ingress of a silicon oxide precursor to a required ingression distance, 'd', during manufacture.

The barrier 12 is preferably a printed barrier. Preferably, the barrier is printed using a digital inkjet method, although alternative printing techniques may also be sued. Alternatively, the barrier may be formed using selective curing, for example by irradiation with infrared (IR) and/or ultraviolet (UV) radiation.

Figure 3 illustrates a plan view along line A-A of the vacuum insulated glazing unit 20 according to the second embodiment of present invention depicted in Figure 2. The vacuum insulated glazing unit comprises spacers 10, a peripheral region 13 and an internal region 14.

As described above with reference to Figure 2, the peripheral region 13 and the internal region 14 are preferably separated by a barrier 12. Preferably the internal region 14 comprises the vacuum, and the peripheral region comprises the hermetic seal 9, which preferably comprises silicon oxide. As also seen in Figure 2, the hermetic seal 9 extends into the cavity from the edge 11 of the vacuum insulated glazing unit 20 by ingression distance 'd'.

In this embodiment the peripheral region 13 comprises an evacuation port 15, for evacuation of the internal region 14 of the cavity 8 without disturbing the hermetic seal 9 Alternatively, the evacuation port 15 may be provided through a sheet of glazing material. Preferably, the evacuation port 15 is sufficiently sealed to maintain the vacuum within the cavity S over the lifetime of the vacuum insulated glazing unit 20. In yet another alternative embodiment (not shown) the vacuum insulated glazing unit may be provided without an evacuation port, when the vacuum insulated glazing unit is manufactured under vacuum conditions.

Examples of the present invention will now be described.

Example 1

An example embodiment of the present invention was prepared according to the following method and is depicted in Figure 4.

Two glass sheets of width 120 mm, height 120 mm and thickness 4 mm were arranged in a face-to-face spaced apart configuration with a distance of 200 pm between the glass sheets. The configuration was formed by applying a spot of epoxy adhesive to each corner of one of the glass sheets and assembling the sheets together with a 200 pm stainless steel shim between the sheets. The shim was removed after the epoxy adhesive had set to produce an assembly.

A silicon oxide precursor solution was introduced into the assembly by capillary action, whereby an edge of the assembly was dipped in a solution comprising 99% by weight polysilazane in the form of perhydropolysilazane (Durazane 0, obtainable from Merck Performance Materials, Germany). It was observed that the capillary action was extremely effective, with the silicon oxide precursor solution moving freely into the cavity.

After introduction of the silicon oxide precursor solution into the cavity, the precursor solution was cured by heating the unit to 200 °C for 2 hours to form an example hermetic seal. Alternatively, the precursor solution may be cured by illumination with UV radiation.

Figure 4 is an image of the first example embodiment. As seen in Figure 4, the vacuum insulated glazing unit 1 comprises a first sheet of glazing material 2 and a second sheet of glazing material 5. A hermetic seal 9 is located between the first sheet of glazing material 2 and the second sheet of glazing material 5. The hermetic seal 9 comprises silicon oxide, derived from a silicon oxide precursor solution in the form of perhydropolysilazane. The hermetic seal 9 extends into the cavity from the edge of the vacuum insulated glazing unit by ingression distance 'd'.

Therefore, as seen from the example it is possible to provide a vacuum insulated glazing unit and a method of manufacturing a vacuum insulated glazing unit that is free from solder glass, compatible with low temperature processing, and cost effective in accordance with the present invention.

Claims

CLAIMS1. A vacuum insulated glazing unit, comprising: (i) a first sheet of glazing material with a first face and a second face; (ii) a second sheet of glazing material with a first face and a second face, arranged in a spaced apart, first face to first face arrangement with the first sheet of glazing material; (iii) a hermetic seal located between the first sheet of glazing material and the second sheet of glazing material to form a cavity between the first faces of the first and second sheets of glazing material; and (iv) one or more spacers located between the first sheet of glazing material and the second sheet of glazing material, wherein the hermetic seal comprises at least 50% by weight silicon oxide.
2. A vacuum insulated glazing unit, comprising: (i) a first sheet of glazing material with a first face and a second face; (ii) a second sheet of glazing material with a first face and a second face, arranged in a spaced apart, first face to first face arrangement with the first sheet of glazing material; (iii) a hermetic seal located between the first sheet of glazing material and the second sheet of glazing material to provide a cavity between the first faces of the first and second sheets of glazing material; and (iv) one or more spacers located between the first sheet of glazing material and the second sheet of glazing material, wherein the one or more spacers comprise at least 50% by weight silicon oxide.
3. A vacuum insulated glazing unit according to claim 0 or claim -1, wherein the hermetic seal and the one or more spacers each comprise at least 50% by weight silicon oxide.
4. A vacuum insulated glazing unit according to any preceding claim, wherein the hermetic seal and/or the one or more spacers comprise at least 70% by weight silicon oxide.
5. A vacuum insulated glazing unit according to any preceding claim, wherein the cavity comprises a pressure of 10-3 mbar or less.
6. A vacuum insulated glazing unit according to any preceding claim, wherein the first and/or second sheets of glazing material comprise glass; preferably wherein the first and/or second sheets of glazing material comprise thermally toughened glass.
7. A vacuum insulated glazing unit according to any preceding claim, wherein the hermetic seal comprises at most 1% by weight lead and/or vanadium.
8. A vacuum insulated glazing unit according to any preceding claim, wherein one or each first face of the first and second sheets of glazing material comprise a low emissivity coating.
9. A vacuum insulated glazing unit according to claim 0, wherein the low emissivity coating comprises silver.
10. A vacuum insulated glazing unit according to any preceding claim, wherein the cavity comprises: a peripheral region; and an internal region, and wherein the peripheral region and the internal region are separated by a barrier.
11. A vacuum insulated glazing unit according to claim 0, wherein the barrier comprises silicon oxide.
12. A vacuum insulated glazing unit according to any preceding claim further comprising an evacuation port.
13. A method for manufacturing a vacuum insulated glazing unit according to any of claims 1 to -1, comprising the steps of: (i) providing a first sheet of glazing material with a first face; (ii) providing a second sheet of glazing material with a first face; (iii) arranging the second sheet of glazing material and the first sheet of glazing material in a spaced apart, first face to first face configuration; (iv) introducing a silicon oxide precursor between the first sheet of glazing material and the second sheet of glazing material and/or applying a silicon oxide precursor to the first face of the first sheet of glazing material and/or applying a silicon oxide precursor to the first face of the second sheet of glazing material; and (v) curing the silicon oxide precursor to form a hermetic seal comprising silicon oxide, wherein the first faces of the first and second sheets of glazing material and the hermetic seal form a cavity.
14. A method for manufacturing a vacuum insulated glazing unit according to any of claims 2 to -1, comprising the steps of: (i) providing a first sheet of glazing material with a first face; (ii) providing a second sheet of glazing material with a first face; (iii) arranging the second sheet of glazing material and the first sheet of glazing material in a spaced apart, first face to first face configuration; (iv) introducing a silicon oxide precursor between the first sheet of glazing material and the second sheet of glazing material and/or applying a silicon oxide precursor to the first face of the first sheet of glazing material and/or applying a silicon oxide precursor to the first face of the second sheet of glazing material; (v) curing the silicon oxide precursor to form one or more spacers comprising silicon oxide; and (vi) introducing a hermetic seal between the first faces of the first and second sheets of glazing material, wherein the first faces of the first and second sheets of glazing material and the hermetic seal form a cavity.
15. A method according to claim 0 or claim 0, wherein the silicon oxide precursor comprises a polysilazane material or an alkali-silicate material.
16. A method according to any of claims 0 to -1, wherein the silicon oxide precursor comprises perhydropolysilazane.
17. A method according to any of claims 0 to -1, wherein the silicon oxide precursor is provided as a solution.
18. A method according to any of claims 0 to -1, wherein the silicon oxide precursor is applied to the first face of the first or second sheets of glazing material by printing.
19. A method according to claim 0 wherein the silicon oxide precursor is applied by inkjet printing.
20. A method according to any of claims 0 to -1, wherein, during curing of the silicon oxide precursor, the temperature of the first and/or second sheets of glazing material are maintained at a temperature from -50 °C to 450 °C.
21. A method according to any of claims 0 to -1, wherein the silicon oxide precursor is cured using UV light.
22. A method according to any of claims 0 to -1, further comprising a step of providing a barrier within the cavity prior to the step of introducing the silicon oxide precursor.
23. A method according to any of claims 0 to -1, further comprising a step of reducing the cavity pressure to 10-3 mbar or less.
24. A method according to any of claims 0 to -1, wherein the hermetic seal and/or the one or more spacers comprise at least 50% by weight silicon oxide; preferably wherein the hermetic seal and/or the one or more spacers comprise at least 70% by weight silicon oxide.
25. Use of a vacuum insulated glazing according to any of claims 1 to -1 or manufactured by the method according to any of claims 0 to -1 in an architectural glazing unit.