Method for making a vacuum insulated glass (vig) window unit with reduced seal height variation

Technical field

In general, the present disclosure relates to a vacuum glazing (VIG) configuration and methods for making a VIG glass. More specifically, the disclosure relates to VIG glass edge weld configuration and edge weld material application methods that reduce the variation in final weld height to reduce the likelihood of a VIG glass crack breaking near the edge weld during the pumping procedure used to empty the space created between glass substrates and the limited VIG glass edge weld. . The present disclosure also relates to the structural arrangement and dimensioning of glass that reduce variability (e.g. tolerance) of the edge weld height before pumping out the space.

BACKGROUND AND SUMMARY OF SAMPLE PERFORMANCES

Vacuum insulated glass (VIG) usually contains at least two glass substrates separated from each other, closing off the pumped or low-pressure space / void between them. The substrates are connected with an edge weld and usually also have spacers between the substrates, which serve to maintain the distance between the glass substrates and to avoid the collapse of the glass substrates due to the environment of reduced pressure existing between them. Some exemplary VIG configurations are disclosed, for example, in US Patent Nos. 5,657,607, 5,664,395, 5,657,607, 5,902,652, 6,506,472 and 6,383,580. Document US2010 / 0330309 A discloses a method of producing a vacuum insulated glass, which comprises applying a weld material at the edge of a first glass substrate and firing a subassembly comprising said first glass substrate and a second glass substrate to form a vacuum insulated glass. FIGURES 1 and 2 show a typical VIG 1 pane and elements forming a VIG 1 pane. For example, the VIG 1 pane may consist of two separated and actually parallel glass substrates 2.3 closing the pumped space with low pressure 6 located between them. The sheets of glass or substrates 2,3 are joined by an edge weld 4, which can be formed, for example, from molten glass solder. Between the glass substrates 2,3 can be arranged a system of support posts / spacers 5, which maintain the distance between the substrates 2,3 of the VIG 1 glass in the presence of a space with reduced pressure 6 between them.

The pump down tube 8 can be hermetically attached, e.g. with glass solder 9, to the hole / hole 10 extending from the inner surface of one of the glass substrates 2 to the bottom of the optional recess 11 in the outer surface of the glass substrate 2, or optionally to the outer surface of the glass substrate 2. A vacuum is connected to the pumping tube 8 to pump the inner space 6 to obtain a low pressure, for example by means of a sequential pumping operation. After pumping space 6 part (e.g. the tip) of the tube 8 is melted to close the vacuum in

- low pressure space 6. The optional depression 11 may contain a closed drainage tube 8. Optionally, a chemical absorber 12. may be placed inside the depression 13 located on the inner surface of one of the glass substrates, for example the glass substrate 2. used to absorb certain impurities that may remain after draining and closing the space 6.

VIG panes with edge welds 4 made by melting the glass solder are usually made by applying a glass frit in the form of a solution (e.g. frit paste) around the edge of substrate 2 (or substrate 3). This glass frit paste finally forms an edge joint 4 of glass solder. Second substrate (e.g. 3) applied to the substrate 2, so as to "into a sandwich" accommodate the spacers / columns 5 between them and the glass frit solution. The entire system, including 2.3 glass substrates, 5 spacers / posts, and weld material (e.g. glass frit in solution or paste) is then heated to a temperature of at least about 500 ° C, at which the glass frit melts, moisturizes the surfaces of glass substrates 2.3 and finally forms a hermetic edge joint 4.

After forming the edge seam 4 between the substrates, underpressure in the low pressure space 6 between the substrates 2.3 is achieved by pumping through the pumping tube 8. The pressure in the space 6 can be lowered by pumping it below atmospheric pressure, e.g. below about 10^-2 Track. To maintain the vacuum in space 6, 2.3 substrates are hermetically connected. Small, high-strength spacers / posts 5 are placed between the substrates to maintain a distance between approximately parallel substrates subjected to atmospheric pressure. As mentioned above, after pumping space 6 between substrates 2,3, the pumping tube can be closed, for example by melting its tip with a laser, or in a similar manner.

After pumping the space to a pressure below atmospheric pressure, the closing of the pumping tube can be achieved by heating the end of the tube used to pump the space to flood the opening and thus close the space of the VIG pane. For example, but without limiting the scope of the invention, this heating and melting can be achieved with the help of laser irradiation of the tip of the pumping tube.

In some cases, VIG glass cracking near the weld was observed during the pumping process. A lot of time and resources were devoted to determining the cause of such cracking during pumping out. Finally, it was determined that changes in weld height could be linked to cracking problems. For example, sometimes the material used to form the edge weld, for example, a frit-containing binder or the like, may be characterized by too high variation in height around the edges of the weld defining the space. After conducting a series of experiments, it was surprisingly found that there was a correlation between tolerance of weld thickness variation and cases of cracking during the draining process (i.e. pumping out) of space. It was also surprising to discover that variation in the height of the weld affects the amount of stress in the VIG pane near the weld during the pumping process of the space created between the VIG glass pane substrates. This process may also be called an extraction procedure or

- pumping out EP 2855816. It was also surprisingly found that too much variation within the weld sometimes results in sufficient stress during pumping, so that the glass of the VIG glass inside the borders, and more specifically near the weld, breaks. For example, but without limiting the scope here, too much variation in the weld height resulted in a gap between posts or spacers, and at least one of the glass substrates that allowed the glass substrate to bend or bend during pumping out. It was found that the glass breaks if the height variation along the entire perimeter of the weld was too great.

It has also been discovered that there may be a number of reasons that cause a large variation in weld height. They consist of the degree of homogeneity of the initial application of raw (i.e. unfired) joint material (e.g. frits) and the stretching or bending of glass substrates during the firing process. It has been found that both of these factors contribute significantly to the variability (i.e. heterogeneity) of the final weld height.

It was then found that reducing the variation in the height of the edge weld, leading to a reduction in stress (i.e. reduction of deflections or stresses in the glass substrate) of the VIG glass during pumping, which reduced the number of VIG glass cracks during pumping out. As a result of experiments, it was possible to reduce the tolerance for weld height variations to small levels by controlling the pre-applied height of the weld material (e.g. frit material), controlling the flow of the weld material during firing, and controlling the even distribution of temperatures during the bonding process. It has been found that such control over changes in the final height of the edge seam that they are in the range below 0.20 mm, more preferably less than about 0.15 mm, and even more preferably less than about 0.10 mm resulted in a significant reduction of cracking during pumping out. It may also be beneficial to provide a firing process that reduces the stretching of the glass substrates during firing by controlling it, and also controls the flow of the weld material, which can also reduce the variation in the height of the edge weld.

The inventors have found that when it comes to achieving less variation in the final edge weld, the control of the initial height of the applied unbaked weld material using the machine application process has significantly improved the homogeneity of the final weld height, to the extent that the final variation of the weld height is within the above tolerance ranges . In addition, control of the homogeneity of the temperature distribution during firing reduced the number of stretches and bends of glass substrates, leading to a further reduction in the variation in weld height. What's more, controlling the flow of the weld material during firing also reduced the variation in the height of the weld, and consisted of a longer firing cycle that allows the weld material to dissolve so as to adjust to the height of the posts / distances during firing.

These and other advantages are provided by a vacuum insulated glass unit not forming part of the present invention, and the present invention consists of: a first substrate and a second substrate; joint material compressed between the first and second substrates and defining the edge of the space created between the first and second substrates and forming a hermetic joint

Between the first and second substrates, wherein the height difference of the weld material around the reduced pressure space is preferably less than about 0.20 mm, more preferably less than or equal to about 0.15 mm, and even more preferably less than or equal to about 0.10 mm. In accordance with the present invention, methods are provided for producing a vacuum insulated glass pane having the features described in claim 1 and consisting of: applying weld material to the first substrate, which weld material has an edge, and the weld material is applied by machine and has a uniform height ranging from about 0.6 mm to 0.9 mm; and firing a subassembly consisting of said first substrate, second ground, and weld material squeezed between them, to create a semi-finished vacuum glazing characterized by a variation in the height of the fired weld material below about 0.20 mm, more preferably less or equal to about 0.15 mm, and even more preferably less or equal to about 0.10 mm.

These and other embodiments and advantages are described herein with reference to some exemplary embodiments and to the following drawings, in which similar reference numbers designate similar elements, and from which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-section of a conventional VIG glass;

FIG. 2 is a top view of a conventional VIG glass;

FIG. 3 is a schematic partial cross section showing the edge portion of an exemplary VIG glass manufactured by the method of the present invention; and

FIG. 4 is a block diagram showing the method of producing VIG glass in which various process conditions are controlled, including the height of the weld material.

DETAILED DESCRIPTION OF EXAMPLES OF PERFORMANCE

Certain exemplary embodiments will be described here in detail with reference to the accompanying drawings, in which similar reference numbers relate to similar elements. It is to be understood that the embodiments described herein are for the purpose of illustration only and not to limit the scope of the invention, and those skilled in the art will understand that without departing from the true spirit and the full scope of the claims appended hereto, a number of modifications may be made thereto.

Referring now to FIG. 3 it shows a schematic section through part of an example VIG 1 glass. The VIG 1 glass has a separate first and second substrate made of transparent glass 2,3, which can be connected by an edge weld 4, which can, for example and without limiting the range, be a vanadium or type VBZ weld or a glass solder weld. Exemplary compositions of vanadium or VBZ type welds are disclosed in US Patent Application Serial No. 13 / 345,963 filed on January 20, 2012. Composition of VBZ welds (i.e. vanadium, barium, zinc) are discussed in 13 / 354,963 and they can be used to form the edge weld 4 in some example embodiments. Conventional glass solder with a frit can also be used to form a weld in some embodiments

5 EP 2855816 edge 4. The use of VBZ-type mixtures for the weld means the use of a lower temperature profile for the formation of the weld, which allows maintaining the desired degree of hardening of the VIG glass, as VBZ mixtures have a lower firing temperature (e.g. <250 ° C) than some other conventional frit mixtures (e.g. about 500 ° C), which can also be used to create joints in VIG windows. It should be understood that the embodiments disclosed herein are equally applicable to VIG configurations using any suitable material for the weld. As indicated above, the edge of the edge seam 4 defines a hermetically closed space 6 between the substrates, which is - as described above - pumped out.

In some examples, 2.3 clear glass substrates may be roughly the same size. However, in some other examples one substrate may be larger than the other to, for example, provide an L-shaped profile at the edge of the VIG glass. One or both 2.3 glass substrates may also optionally have at least one coating material (not shown), for example and without limiting the scope of the invention, an energy-saving coating. It should be understood that different coatings may be present on the inner surface of at least one of the glass substrates 2,3, and that such coatings provide various favorable characteristics of the VIG 1 glass. In some examples, the VIG glass has a visible transmission of at least about 30%, more preferably at least about 40%, even more preferably at least about 50%, and even more preferably at least about 60% or 70%.

Between the glass substrates 2.3, a system of support posts / spacers 5 may be attached to maintain the distance between the substrates after the pressure has dropped below atmospheric pressure in the space 6 between the substrates 2.3. In some exemplary embodiments, these spacers may have, for example, a height of from about 0.1 to 1.0 mm, more preferably from about 0.2 to 0.4 mm. The height of the spacers can determine the height of the vacuum space 6. As emphasized above, the spacers 5 preferably have a small enough shape to not be conspicuous. According to some exemplary embodiments, the spacers may be made of or include glass solder, glass, ceramics, metal, polymer, or any other suitable material. In addition, the spacers 5 may be, for example, generally cylindrical, round, spherical, small-coin, C-shaped, cushion-shaped or in any other applicable shape.

The pumping tube (not shown in FIG. 3) is used in the process of pumping out space 6 between substrates 2,3, for example by connecting a vacuum pump to the pumping tube and pumping it to low pressure, i.e. pressure below atmospheric pressure. In a preferred example, the pressure in space 6 is, for example, preferably lower than about 10^-2 Tor, and even more preferably lower than about 10^-3 Tor, and even more preferably below about 5x10^-4 Track. After pumping space 6, the pumping tube can be closed, for example by melting its tip by means of suitable means, such as, for example, a laser. VIG glass can be used, but without

- EP 2855816 limitations of the catalog of applications, as windows in residential, office buildings, sheep apartment, in doors and / or the like.

According to some examples, differences in the height of the weld are monitored in the VIG shaft to reduce stress (i.e. reduction of torsional forces in the glass substrate) during pumping, and thus the occurrence of VIG glass cracking during pumping is reduced. As a result of many experiments we have carried out, we have been able to reduce the tolerance of weld height variations, for example - and not only by controlling the flow of weld material during firing and / or controlling the uniformity of temperatures during the weld formation process. It was found that controlling the final variation in the height of the weld so that it was in the range up to about 0.20 mm, more preferably up to about 0.15 mm, and even more preferably up to about 0.10 mm resulted in a significant reduction of cracking during pumping out. "Variation" can be considered as the difference between the maximum weld height and the minimum weld height. Thus, throughout the entire edge seam surrounding the reduced pressure space, the maximum height of the edge seam differs from the minimum height of the edge seam by less than 0.20 mm, more preferably by less than about 0.15 mm, and even more preferably by less than about 0.10 mm. According to some example embodiments, for example and without limitation, differences in the height of the weld can be reduced by providing a machine application process that more closely controls the height of the pre-applied weld material (e.g. frits). According to the invention, to reduce the stretch or curvature of glass substrates of VIG glass that can contribute to variation in the height of the formed joint, a more controlled firing process is used, characterized by less temperature variation and longer firing time. In addition, in accordance with further exemplary embodiments, a longer firing process can be used to control the flow of the weld material during firing, for example by allowing the weld material to flow down so that it matches the height of the posts or distances during firing, thereby further reducing variation weld height.

According to the invention, a method for producing VIG glass is disclosed. The height of the pre-applied weld material is controlled by a machine applying the pre-weld material to one of the VIG glass surfaces. The height of the pre-applied joint material may depend on the subsequent firing process. According to an unreserved embodiment, when applying the short-wave infrared (SWIR) firing material, the raw, unbaked thickness (i.e. dry measured) frits (i.e. weld material) may preferably be in the range of from about 0.4 mm to 0.9 mm, or more preferably in the range of from about 0.5 mm to 0.8 mm, and even more preferably from about 0.6 mm to about 0.7 mm. Due to the relatively short SWIR processing time, the tolerance for the initial applied height of the frit is lower than for processes with a longer firing cycle. According to the invention, for longer convection-type firing, heights of raw, unfired frits ranging from about 0.6 mm to 0.9 mm are allowed, due to the longer peak soaking times that allow the weld material to

- flowing and solidifying at the height of posts or distances. In accordance with yet other embodiments, the thermal cycle may be controlled to provide additional control or reduce the variation in weld height, for example by reducing the number of stretches and twists on the VIG glass substrate. According to the example, temperature differences can cause the glass substrates to stretch and twist, resulting in further, unfavorable variation in joint height. According to the invention, the firing conditions are controlled to ensure greater uniformity of temperatures <2.0 ° C and to provide sufficient time (20-30 minutes) for the glass to stabilize and flatten by allowing the glass substrates to heat and flatten evenly.

Referring again to FIG. 3 it shows the final height of the weld H for the edge weld 4. According to the invention, the variation in height H of the edge weld 4 along the edge of the edge weld 4 of the VIG 1 pane is controlled by controlling the height variation of the pre-applied weld material (e.g. frits). As noted above, a preferred example height of the applied frit may depend, for example, on the type of process used to burn the VIG glass. According to some non-claimed examples using the SWIR firing process, the height of the pre-applied weld material may preferably be in the range of from about 0.4 mm to 0.9 mm, or more preferably in the range from about 0.5 mm to 0.8 mm, and even more preferably from about 0.6 mm to 0.7mm. According to the invention, when longer convection type firing cycles are used, the pre-applied height of the weld material (i.e. the height of the raw, unfired frit) is in the range of about 0.6 mm to 0.9 mm. The differences for longer convection type firing may be larger because this type of firing process may be characterized by longer peak heating times. According to the exemplary embodiments, the pre-application of the frit can be performed by a machine process due to the narrower tolerance range established for the exemplary embodiments described above. Furthermore, according to some example embodiments, longer peak heat times may be beneficial to facilitate the flow of the weld material during firing and to help flatten glass substrates, which will also help to further reduce the variability of the final weld height. In addition, as indicated above, temperature differences can cause the glass substrates to stretch and twist, resulting in further unfavorable differences in joint height. Thus, according to the invention, firing conditions are controlled to ensure greater uniformity of temperature distribution (in the range of about <2.0 ° C) and provides sufficient soak time (in the range of about 20-30 minutes) to allow the glass to stabilize and flatten, by allowing glass substrates to achieve an even temperature and the weld material to flow. The result is a VIG glass pane with limited variation in weld height, in which the final weld has a variable height of less than about 0.20 mm, more preferably less than or equal to 0.15 mm, and even more preferably less than or equal to about 0.10 mm.

FIG. 4 is an example block diagram illustrating a method for producing a VIG glass pane which shows the method according to the invention. As shown in FIG. 4, providing the first glass substrate in step S1. The glass substrate can remain

- machined to provide certain structural features of a typical VIG glass, for example distances or posts, or the like. Then the first substrate can be provided with a weld material applied, for example and without limiting the range, around the edge of the area to be closed and which area together with the second substrate (as described below) defines the space in step S3. As noted above, a whole range of frit-containing materials or bonding materials can be used to form the VIG glass joint. For example and without limiting the scope, the weld may be or include a vanadium based or VBZ weld. Examples of weld compositions based on vanadium or VBZ are disclosed in US Patent Application Serial No. 13 / 354,963 of January 20, 2012, mixtures based on VBZ (i.e. vanadium, barium, zinc) are discussed in 13 / 354,963 and can, in some embodiments, be used for the edge weld 4. Conventional glass solder with frit can also be used for the edge seam 4 in some example embodiments. According to an unreserved example, the weld material is applied in S3 to a machine height depending, for example, on the type of firing subsequently used. For example, when using short-wave infrared (SWIR) firing, the height of the raw, unfired frit (i.e. weld material) may preferably be in the range from about 0.4 mm to 0.9 mm, or more preferably in the range from about 0.5 mm to 0.8 mm, and even more preferably from about 0.6 mm to 0.7 mm. As mentioned above, due to the relatively short SWIT processing time, the tolerance of the application height of the raw frit may be lower than in the case of firing processes with a longer cycle. In the method of the invention, which uses a longer convective firing cycle, as described in more detail above, the raw frit thicknesses are in the range of about 0.6 mm to 0.9 mm due to the longer peak heating times allowing the weld material to run down or solidify in height bollards or distances. After applying the joint material at S3, a second glass substrate is supplied at S5, which covers the posts and the unburned frit material by squeezing them between the first and second glass substrates. The first and second glass substrates, together with the frit of the weld material, are then fired in step S7 using any suitable technique, for example and without limiting the scope of the invention - SWIR or long-cycle convection. The VIG glass produced is characterized by reduced variation in the final weld height, which variation in the final weld height is less than about 0.20 mm, more preferably less than or equal to about 0.15, and even more preferably less than or equal to about 0.10 mm.

Thus, in some non-claimed exemplary embodiments of the present invention there is provided a composite vacuum pane (VIG) consisting of: a first and a second substrate; weld material compressed between the first and second substrates and defining the edge of the space formed between the first and second substrates, in which space between the substrates there is a lower pressure than atmospheric, and the joint material forming the hermetic joint between the first and second substrate is characterized by that the variation in the height of the weld material around the entire space is less than about 0.20 mm.

- 9 EP 2855816

In the VIG shaft described in the immediately preceding paragraph, the variation in the height of the weld material along its entire length around the space may be less or equal to about 0.15 mm, more preferably less or even about 0.10 mm.

In the VIG glass described in any of the previous two paragraphs, it is also possible to place a plurality of spacers located between said first and second substrates.

In the VIG shaft described in any of the three previous paragraphs, the height of the joint material can be virtually equal to the height of the distances between the substrates.

In the VIG glass described in any of the previous four paragraphs, said first and second substrates may be glass substrates.

In the VIG shaft described in any of the previous five paragraphs, said joint material may consist of a frit-containing adhesive.

In the VIG glass described in any of the previous six paragraphs, said weld material may contain vanadium.

The terms "on", "resting" and the like used herein should not be construed as meaning that the two elements are directly adjacent, unless expressly stated otherwise. In other words, the first layer may be "on" or "resting" on the second layer even if there are one or more layers between them.

Although some exemplary embodiments have been described and disclosed herein, it is understood that the embodiments described herein are for the purpose of illustration and not limitation, and those skilled in the art will understand that various modifications may be made to them without departing from the true spirit and the full scope the following claims.

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- EP 2855816