WO2000029702A1

WO2000029702A1 - Insulating glazing unit using a foamed sealant and method for manufacturing the same

Info

Publication number: WO2000029702A1
Application number: PCT/US1999/027110
Authority: WO
Inventors: Gerhard Reichert
Original assignee: Edgetech I.G., Inc.
Priority date: 1998-11-16
Filing date: 1999-11-15
Publication date: 2000-05-25
Also published as: AU1625900A

Abstract

A glazing unit having a pair of glazing sheets spaced apart by a spacer assembly includes a moisture seal that prevents moisture from entering the cavity of the glazing unit through the spacer assembly from the surrounding atmosphere. The moisture seal is formed, in part, by a foamed sealant. Foaming the sealant allows less raw dense sealant to be used decreasing the cost of the glazing unit. The foamed sealant has the advantage that the length of the moisture barrier paths can be increased while not increasing the amount of raw sealant used. The foamed sealant also increases the flexibility, insulation properties, and working temperature range of the spacer assembly. The spacer may also contain a desiccant matrix that adsorbs any moisture in the cavity of the glazing unit. The desiccant matrix may also be foamed. The foamed sealant and foamed desiccant matrix may be used with a variety of spacer applications.

Description

INSULATING GLAZING UNIT USING A FOAMED SEALANT AND METHOD FOR MANUFACTURING THE SAME

BACKGROUND OF THE INVENTION

Technical Field

The present invention relates generally to insulating glazing units, and more particularly, to insulating glazing units that use a sealant to create a moisture- impervious seal between the surrounding atmosphere and the interior cavity of the glazing unit. Specifically, the present invention relates to the use of a foamed sealant in combination with glazing unit spacers in order to decrease the overall volume of the sealant used in the glazing unit and to increase the insulation and sealing properties of the spacer assembly.

Background Information

Insulating glazing units include at least two substantially parallel glazing sheets spaced apart by a spacer assembly disposed about the periphery of the glazing sheets. The spacer assembly creates the insulating cavity between the glazing sheets and holds a desiccant material for maintaining a dry cavity. The spacer assembly also provides structural support between the glazing sheets and seals the interior cavity of the glazing unit from the surrounding atmosphere. The sealing function of the spacer assembly is particularly important to prevent moisture from entering the cavity between the glazing sheets and condensing on the interior surfaces of the glazing sheets. Condensation is highly undesirable in glazing units and is an indication of an ineffective seal or the saturation of the desiccant material. Glazing units that allow condensation to form in the cavity between the glazing sheets quickly acquire an undesirable image with consumers. It is thus important for the manufacturer of glazing units to create a strong, effective seal between the cavity of the glazing unit and the surrounding atmosphere. The moisture barrier is formed in many glazing units by creating an outwardly-facing sealant channel between the spacer assembly and the glazing sheets. The sealant channel is then filled with a sealant to create an effective seal. In many cases, the sealant-filled channel forms the moisture barrier between the cavity of the glazing unit and the surrounding atmosphere that prevents moisture from entering the cavity saturating the desiccant and condensing. One commonly-used sealant is hot-melt butyl. Poyisobutylene, silicones, polyurethanes, chemically-curing one-part hot-melts, and polysulfides are also used to form this barrier. In the past, it has been generally understood that it is desirable to create an outwardly facing channel to receive a substantial volume of sealant such that the length of the moisture-vapor path is as long as possible. The increased length of the path increases the life and the effectiveness of the barrier between the cavity and the surrounding atmosphere. It has also been desired in the art to use a dense sealant having few air pockets so that the moisture-vapor path between the cavity and surrounding atmosphere is not shortened by any air bubbles or pockets. A dense sealant has also been thought to be necessary to retain the high quality seal as the glazing unit expands and contracts in response to temperature and pressure variations. The moisture seal also experiences stresses when the glazing unit is exposed to the wind.

The material that forms the moisture seal has also been used in the prior art to form a structural bond between the two outer glazing sheets. When a structural bond is required to form the glazing unit, a sealant that sets up or cures over time is used in the sealant channel so that the material disposed in the sealant channel forms a second structural element between the glazing sheets in addition to the spacer element. In the past, the materials that were used to form the structural element had a relatively high moisture/vapor transmission rate. As a result, the depth of the channel was increased and the density of the material was desired to be as high as possible. The desire to create a long, tortuous moisture-vapor path with a dense sealant has resulted in long moisture-vapor paths at the critical glass interfaces that are filled with sealant to create a long-lasting seal. The increased volume of the sealant increases the overall cost of the glazing unit. It is thus desired in the art to provide a sealant and a method for forming a moisture seal in a glazing unit that uses a significantly lower volume of sealant than in the past thereby reducing the overall cost of the glazing unit.

It is also desired to provide a sealant system that offers greater insulation to the spacer assembly against heat transfer through the assembly. The new foamed sealant system should be able to be retrofit with the existing technology for applying the sealant to the glazing units reducing the time and labor devoted to sealant supply changeover. As such, the new foamed sealant system should be able to be applied by existing sealant application devices. Ideally, the new sealant system should function equally well with a wide variety of existing spacers.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an objective of the present invention to provide a method for forming the moisture barrier or structural seal in an insulating glazing unit that uses substantially less sealant than the methods known in the art.

Another objective of the present invention is to provide a method forforming the moisture barrier in an insulating glazing unit that uses a foamed sealant to form the moisture barrier.

Yet another objective of the present invention is to provide a method for forming the moisture barrier in an insulating glazing unit that doubles the length of the moisture barrier seal path while using substantially the same volume of sealant as in the prior art seals.

Still another objective of the present invention is to provide a method for forming the moisture seal in an insulating glazing unit that may be performed by automated machinery or manual equipment.

A further objective of the present invention is to provide a method for forming the moisture seal in an insulating glazing unit that may be used with a variety of spacers known in the art. Yet a further objective of the present invention is to provide a method for forming the moisture seal in an insulating glazing unit that may be used with a variety of sealants known in the art such as hot-melt butyl, polyisobutylene, polysulfides, polyurethane, chemically-curing one-part hot-melts, or silicone. Yet another objective of the present invention is to provide a glazing unit having a spacer assembly using a foamed sealant that improves the insulating properties of the glazing unit.

Still an additional objective of the present invention is to provide a glazing unit having a spacer assembly using a foamed sealant that cures to form a structural seal.

Another objective of the present invention is to provide a glazing unit having a spacer assembly using a foamed sealant that provides improved flexibility over their dense counterparts to accommodate the expansion and contraction of the glazing unit. A further objective of the present invention is to provide a glazing unit having a spacer assembly using a foamed sealant that expands when it is applied to the spacer and the glazing sheets so that the sealant forces itself against the spacer and the glazing sheets to create a strong seal and bond between the glazing sheets and the spacer. Another objective of the present invention is to provide a glazing unit having a spacer assembly using a foamed sealant that has an improved working temperature range.

A further objective of the invention is to provide a glazing unit that uses an adhesive or sealant-based desiccant matrix that is foamed. Another objective of the present invention is to provide a glazing unit having a spacer using a foam sealant that is of simple construction, that achieves the stated objectives in a simple, effective and inexpensive manner, and that solves the problems and that satisfies the needs existing in the art.

These and other objectives of the present invention are achieved by the glazing unit including a first outer glazing sheet, a second outer glazing sheet, a spacer disposed between the first and second glazing sheets, and a foamed sealant disposed adjacent said spacer and glazing sheets.

Yet other objectives of the present invention are achieved by a method for forming a glazing unit including steps of positioning a spacer between first and second glazing sheets to form an outwardly-facing sealant channel between the spacer and the glazing sheets and filling the sealant channel with a foamed sealant.

Still other objectives of the present invention are achieved by a spacer having a longitudinal structural member and a foamed sealant substantially surrounding the structural member.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the invention, illustrative of the best mode in which applicant contemplated applying the principles of the invention, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims.

Fig. 1 is a sectional view of a prior art spacer assembly disposed between a pair of glazing sheets;

Fig. 2 is a schematic diagram of one embodiment of a gas injection system for creating foamed sealants;

Fig. 3 is a sectional view of a spacer assembly using the foamed sealant; Fig. 3a is an enlarged view of the area of Fig. 3 enclosed by a circle; Fig. 4 is a sectional view of another embodiment of a spacer assembly using foamed sealant; Fig. 5 is a sectional view of another embodiment of a spacer assembly using foamed sealant;

Fig. 5a is a sectional view of the spacer of Fig. 5 using a foamed desiccant matrix;

Fig. 6 is a sectional view of another embodiment of a spacer assembly using at least one foamed sealant; Fig. 7 is a sectional view of another embodiment of a spacer assembly using at least one foamed sealant;

Fig. 8 is a sectional view of another embodiment of a spacer assembly using foamed sealant to substantially surround a structural member; Fig. 9 is a sectional view of another embodiment of a spacer assembly using at least one foamed sealant; and

Fig. 10 is a sectional view of a different embodiment of the spacer of Fig. 9 using at least one foamed sealant.

Similar numbers refer to similar parts throughout the specification.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A prior art glazing unit is depicted in Fig. 1 and is indicated generally by the numeral 10. Glazing unit 10 includes a pair of outer glazing sheets 12 and 14 that are spaced apart by a spacer 16. In the embodiment of the prior art depicted in Fig. 1 , spacer 16 is formed from a structural foam material that has desiccant dispersed throughout its body. Spacer 16 is disposed inwardly of the outer edges 18 of glazing sheets 12 and 14 to form an outwardly-facing sealant channel 20. Spacer 16 is connected to the inner surfaces 22 and 24 of glazing sheets 12 and 14 by an appropriate adhesive. In the prior art, sealant channel 20 was filled with a sealant 26 such as hot- melt butyl, polyurethane, and polysulfide . Another possible type of sealant is a one-part hot-applied or warm-applied sealant that cures to form a structural element in addition to spacer 16 such as PRC 590/595 made by Courtaulds Aerospace, Inc. of Glendale, California or Bostik 9190 made by Bostik of Huntington Valley, Pennsylvania. Hot-melt butyl is one sealant that is commonly used to fill sealant channel 20. In the past, these sealants have been applied to glazing unit 10 in a way such that they are dense and installed without air pockets. The dense sealant forms an excellent moisture seal but has limited flexibility. Sealant 26 contacts inner surfaces 22 and 24 of glazing sheets 12 and 14 as well as the outer surface 28 of spacer 16 to seal the cavity 30 of glazing unit 10 from the surrounding atmosphere. The seal is important because a break in the seal results in eventual condensation in glazing unit 10.

In the past, the manufacturers of glazing units have had to balance the need for a strong seal against the expense of adding more sealant 26 to form the 5 seal. It is generally accepted that a longer moisture seal path is better but that such a longer seal often requires a larger volume of sealant. In the embodiment of prior art glazing unit 10 depicted in Fig. 1 , sealant channel 20 is approximately 3/16 inch deep as indicated by the dimension line labeled by the numeral 32. It is thus desired in the art to provide a glazing unit having a longer moisture seal

10 path without increasing the amount of sealant 26 used.

In accordance with one of the objectives of the invention, a glazing unit 100 is provided having an outwardly-facing sealant channel 120 that is approximately twice as deep as channel 20 of the prior art. Glazing unit 100 of the present invention is depicted in Fig. 3 and includes the same outer glazing sheets 12 and

15 14 and spacer 16 as prior art glazing unit 10. Spacer 16 is positioned inwardly from outer edges 18 to form channel 120 having a depth, indicated by numeral 132, that is approximately 3/8 inch. Channel 120 is then filled with a foamed sealant 126. Foamed sealant 126 in channel 120 thus forms a moisture seal that is about twice as long as the moisture seal of the prior art.

20 Foamed sealant 126 allows the same volume of dense sealant 26 to fill approximately twice the volume of sealant channel 120 by using closed cell foaming technology to foam sealant 26. Foamed sealant 126 includes a plurality of gas bubbles 127 that are dispersed throughout its body. Gas bubbles 127 increase the volume of sealant 126 without increasing the volume of dense sealant

25 26. The closed cell foaming technology provides a foamed sealant that forms a moisture seal with glazing sheets 12 and 14 that is virtually as effective as the moisture seals of the prior art that was formed with sealant 26. Such a result is contrary to the understanding in the art that a dense sealant is required to form an adequate moisture seal. It has, however, been found that the gas bubbles 127 in

30 the closed cell foam do not substantially decrease the ability of the foam to form a moisture seal. The foamed sealant functions, in part, because the material expands when it is inserted into channel 120. The expansion is caused by the gas that is dispersed in the sealant expanding when the sealant has the dispersed gas exits the application nozzle of the application device. The expanding foam forces itself against inner surfaces 22 and 24 of glazing sheets 12 and 14 thus causing the bubbles 127 to "wet out" and form a skin 128 or a substantially dense continuous layer 128 of sealant adjacent inner surfaces 22 and 24. Skin 128 is an essentially solid, continuous sealant and is located at the critical areas adjacent glazing sheets 12 and 14. These areas are critical because the moisture seal is weakest where the sealant must bond to sheets 12 and 14. Bubbles 127 that remain in foamed sealant 126 do not substantially take away from the sealing properties of sealant 26 and actually increase the insulating properties of glazing unit 100.

Foamed sealant 126 may be produced by any of the numerous foaming methods known in the art. A generic foaming process is depicted in Fig. 2 and includes a supply reservoir 150 of sealant 26 and a supply reservoir 152 of gas 127. Supply reservoirs 150 and 152 are connected to a mixer 154 through controllable valves 156 and 158, respectively. Mixer 154 is designed and adapted to thoroughly mix gas 127 with sealant 26 to form the closed cell foamed sealant 126. A controller 160 is also provided that allows the manufacturer to control the density of foamed sealant 126 and the speed of its production. Mixer 154 is connected to an application nozzle 162 that may be part of a hand-held applicator or an applicator nozzle in an automated system. One exemplary foaming system is disclosed in US Patent 5,480,589 to Belser et al. assigned to the Nordson Corporation. Other methods of forming a closed cell foam with a sealant are known in the art and may also be used to form foamed sealant 126. The mix of gas and sealant is controlled by the user depending on the properties of the sealant and gas. In one embodiment, the volume of the sealant is doubled by the addition of the gas. In other embodiments of the invention, the mix of gas and sealant may vary. Depending on the application, foamed sealant 126 may be from about 10% gas to about 90% gas. The amount of gas in the sealant depends on the application of the foamed sealant. Foamed sealant 126 has better insulation properties than dense sealant 26 because it includes the gas bubbles 127. Foamed sealant 126 thus has a better range of working temperatures because it does not transfer heat through its body as fast as dense sealant 26 that is known in the art. Foamed sealant 126 is also more flexible than dense sealant 26 so that glazing unit 100 is better able to accommodate the movement of glazing sheets 12 and 14.

Another embodiment of the glazing unit of the present invention is depicted in Fig. 4 and is indicated generally by the numeral 180. Glazing unit 180 includes some of the same elements as glazing unit 10 of the prior art with the exception of sealant 126. In this embodiment, spacer 16 is positioned to form a sealant channel 182 that has a depth of approximately 3/16 inch as indicated by numeral 184. Sealant channel 182 thus has the same dimensions as channel 20 of the prior art glazing unit 10. The use of foamed sealant 126 to fill channel 182 allows the manufacturer to substantially decrease the volume of sealant required to form glazing unit 180. When a 50 percent foamed sealant is used, the savings related to sealant use is approximately 50 percent. Foamed sealant 126 thus allows the manufacturer to reduce the cost of glazing unit 180 while providing the same length moisture seal path as in the prior art.

The use of foamed sealant 126 with another type of existing spacer is depicted in Fig. 5. The spacer 202 depicted in Fig. 5 is manufactured and sold under the trademark Intercept. Spacer 202 is formed from metal and is substantially U-shaped. Spacer 202 is coated about its exterior surfaces with a sealant such as hot-melt butyl when it is manufactured. Spacer 202 is then positioned between outer glazing sheets 12 and 14 and passed through a heated roller press to fix spacer 202 with respect to glazing sheets 12 and 14. Fig. 5 depicts the use of foamed sealant 126 to surround spacer 202 so that the volume of sealant used to form glazing unit 200 can be reduced. Another embodiment of the spacer assembly of Fig. 5 is depicted in Fig. 5(a). Spacer 202 of Fig. 5 typically includes a desiccant matrix 204 disposed within spacer 202. Desiccant matrix 204 adsorbs moisture from the cavity 206 of glazing unit 200. One problem with this configuration is that a person looking through glazing unit 200 can look into spacer 202 and see desiccant matrix 204. Spacer 202 appears to be mostly empty because desiccant matrix 204 does not come close to filling spacer 202. Fig. 5(a) discloses a different embodiment of glazing unit 200 where desiccant matrix 204 has been replaced with a foamed desiccant matrix 208 that 5 substantially fills spacer 202. Desiccant matrix 208 does not perform any sealing functions and provides very little structure to spacer 202 and thus desiccant matrix 208 may be foamed up significantly more than foamed sealant 126. For instance, foamed desiccant matrix 208 may be foamed to 70% so that it substantially fills spacer 202 while not increasing the amount of material used in glazing unit 200.

10 Foamed desiccant matrix 208 improves the insulation properties of spacer 202 by filling spacer 202. Foamed desiccant matrix 208 thus provides a more aesthetic appearance to glazing unit 200. Foamed desiccant matrix 208 is even more permeable than matrix 204 and thus improves the fluid communication between the desiccant and cavity 206 to adsorb moisture from cavity 206 faster than with

15 matrix 204.

Another embodiment of a spacer assembly and glazing unit is depicted in Fig. 6 and is indicated generally by the numeral 220. Glazing unit 220 includes a tubular spacer 222 that contains a plurality of desiccant beads 224. A series of holes 225 are provided in spacer 222 to allow moisture to reach desiccant beads

20 224. Spacer 222 is typically bonded to glazing sheets 12 and 14 by an adhesive such as polyisobutylene 226. Sealant 226 may also be foamed to decrease its cost. Spacer 222 is positioned inwardly from outer edges 18 to form sealant channel 228. Sealant channel 228 is filled with a foamed sealant 229 that cures or sets up after it is applied such that foamed sealant 229 provides an additional

25 structural element between glazing sheets 12 and 14. In the past, structural sealants had a significantly higher moisture/vaportransmission rate than a sealant such as hot-melt butyl. New structural sealants have, however, been recently developed that have a moisture/vapor transmission rate that is similar to if not better than hot-melt butyl. These structural sealants, such as PRC 590/595 and

30 Bostik 9190, are suitable for being foamed because the foaming does not degrade the moisture/vapor transmission rate to a point where it can not be used to form a moisture barrier seal in an insulating glazing unit.

Another embodiment of an insulating glazing unit is depicted in Fig. 7 and is indicated generally by the numeral 250. Glazing unit 250 includes a spacer 252 that has a longitudinal indentation 251 disposed in its outwardly facing surface.

A pair of sealant channels 253 are disposed on either side of indentation 251.

Channels 253 are filled with foamed sealant 229 while indentation 251 is left empty. The amount of foamed sealant used with glazing unit 250 is thus further reduced compared to the amount used in glazing unit 220 by providing two sealant channels 253. Spacer 252 of glazing unit 250 also includes holes 225 that provide fluid communication between the cavity 230 and desiccant beads 224. Sealant

226 may also be foamed to reduce its cost.

Another embodiment of an insulating glazing unit is depicted in Fig. 8 and is indicated generally by the numeral 300. Glazing unit 300 includes a spacer 302 that has a longitudinal structural member 304 substantially surrounded by a sealant 306 that may be foamed to substantially reduce the amount of raw sealant used to form glazing unit 300. Longitudinal structural member 304 is disposed in a serpentine pattern throughout foamed sealant 306 to provide structure to spacer

302. The upper portion 308 and lower portion 310 are depicted in dashed lines. Spacer 302 is fabricated by extruding foamed sealant 306 adjacent spacer member 304. Foamed sealant 306 preferably substantially surrounds spacer member 304 as shown in Fig. 8. Spacer assembly 302 is then stored for later use. Spacer 302 is thus a self-contained pre-formed spacer. Foamed sealant 306 forms the moisture barrier in glazing unit 300 because spacer 302 is bonded to glazing sheets 12 and 14 when glazing unit 300 is passed through a heated roller press. The heated roller press wets out the edges 312 of foamed sealant 306 that are adjacent inner surface 22 and 24 of glazing sheets 12 and 14, respectively.

As discussed above with respect to Fig. 3a, the wetted out area is essentially solid sealant and functions as an effective moisture barrier seal. Another embodiment of a spacer assembly and glazing unit is depicted in

Fig. 9 with the glazing unit being indicated generally by the numeral 350. Glazing unit 350 includes a spacer 352 that includes a foamed sealant 354 surrounding a structural block 356 that may be fabricated from foam-. A desiccant matrix 358 is disposed on the inwardly facing surface of foamed sealant 354. Desiccant matrix 358 may also be foamed as discussed above with respect to Fig. 5a. In this embodiment, a moisture barrier seal is also formed when glazing unit 350 is passed through a heated roller press causing edges 360 of foamed sealant 354 and edges 361 of desiccant matrix 358 to wet out and form the moisture barrier. Spacer 350 is manufactured in the same manner as spacer 300 such that it is preformed. Another embodiment of a glazing unit similarto glazing unit 350 is depicted in Fig. 10 and is indicated generally by the numeral 370. Glazing unit 370 also includes foamed sealant 354 and structural block 356. An additional moisture barrier 372 that may be fabricated from metal or a plastic is disposed inwardly of foamed sealant 354. Barrier 372 may extend entirely between inner surfaces 22 and 24 of glazing sheets 12 and 14 but may also be spaced from glazing sheets 12 and 14 as depicted in Fig. 10. In this situation, a secondary sealant 374 is provided between the edges of barrier 372 and glazing sheets 12 and 14.

Accordingly, the improved insulating glazing unit using a foamed sealant and method for manufacturing the same is simplified, provides an effective, safe, inexpensive, and efficient device that achieves all the enumerated objectives, provides for eliminating difficulties encountered with prior devices, and solves problems and obtains new results in the art.

In the foregoing description, certain terms have been used for brevity, clearness, and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirement of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed.

Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described. Having now described the features, discoveries, and principles of the invention, the manner in which the insulating glazing unit using a foamed sealant and method for manufacturing the same is constructed and used, the characteristics of the construction, and the advantageous new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts, methods, and combinations are set forth in the appended claims.

Claims

1. A glazing unit comprising: a first outer glazing sheet; a second outer glazing sheet; a spacer member disposed between said first and second glazing sheets; and a foamed sealant disposed adjacent one of said spacer member and said glazing sheets.

2. A glazing unit according to claim 1 , wherein said spacer member is disposed inward of the edges of said glazing sheets to form a sealant channel between said glazing sheets and said spacer member, said channel disposed outwardly of said spacer member; said channel substantially filled with said foamed sealant.

3. A glazing unit according to claim 2, wherein said channel has a depth and said spacer member has a depth, said depth of said channel being substantially twice said depth of said spacer member.

4. A glazing unit according to claim 3, wherein said depth of said channel is substantially 3/8 inch.

5. A glazing unit according to claim 1 , wherein said foamed sealant is foamed in a range of substantially 10 to 90 percent.

6. A glazing unit according to claim 5, wherein said foamed sealant is foamed substantially 50 percent.

7. A glazing unit according to claim 6, wherein said sealant is foamed with nitrogen.

8. A glazing unit according to claim 1 , wherein said foamed sealant has edges that are wetted out adjacent at least one of said glazing sheets.

9. A glazing unit according to claim 8, wherein a skin of sealant is formed adjacent at least one of said glazing sheets.

10. A glazing unit according to claim 1 , further comprising a layer of foamed desiccant matrix disposed adjacent said spacer member.

11. A glazing unit according to claim 1 , further comprising a desiccant material disposed within said spacer member.

12. A glazing unit comprising: a first outer glazing sheet; a second outer glazing sheet; a spacer member disposed between said first and second glazing sheets; and a foamed desiccant matrix disposed adjacent said spacer member.

13. A method for forming a glazing unit comprising the steps of: positioning a spacer member between first and second glazing sheets to form an outwardly-facing sealant channel between the spacer member and the glazing sheets; and dispensing a foamed sealant into the sealant channel;

14. The method according to claim 13 wherein the step of dispensing includes the step of adding a sealant having a dispersed gas to the sealant channel, the gas expanding when released into the sealant channel to form a foamed sealant.

15. The method according to claim 13, wherein the step of adding is performed by hand-held gunning equipment.

16. The method according to claim 13, wherein the step of adding is performed by automated gunning equipment

17. The method according to claim 13, further comprising the step of wetting out the foamed sealant against the glazing sheets.

18. The method according to claim 13, further comprising the step of substantially filling the sealant channel with the foamed sealant.

19. The method according to claim 13, further comprising the step of pumping a sealant and a gas through a mixer to form the sealant having the dispersed gas.

20. A method of forming a spacer assembly comprising the steps of: positioning a spacer member with respect to a sealant extruder; and dispensing a foamed sealant on the spacer member with the sealant extruder.

21. The method according to claim 20, wherein the step of dispensing includes the steps of providing a sealant having a dispersed gas and allowing the sealant to expand to form a foamed sealant on the spacer member.

22. The method according to claim 20, further comprising the step of substantially surrounding said spacer member with the foamed sealant.

23. The method according to claim 20, further comprising the step of applying a layer of foamed desiccant matrix adjacent the foamed sealant.

24. The method according to claim 20, further comprising the step of applying a layer of foamed desiccant matrix adjacent the spacer member.