CA1056217A - Add-on multiple glazing - Google Patents

Abstract

ABSTRACT
The invention relates to an architectural glazing unit for converting installed glazing to multiple glazing, comprising no more than one transparent pane, a spacer element adjoining marginal portions of a major surface of the pane around the perimeter of the pane and spaced from the peripheral edges of the pane and a body of at least partially uncured poly-meric sealant adhered to the major surface between the spacer element and the peripheral edges of the pane around the perimeter of the pane. The sealant has a dimension normal to the major surface greater than that of the spacer element, the sealant having a moisture vapor transmittance of less than about 15 grams of water per 24 hours per square meter for 1 mil thickness and, at room temperature, is coherent and tacky but flowable under pressure. The unit provides for easier installation and a more effective and longer lasting multiple glazed product.

Description

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` This is a division of application Serial No. 221,741 filed on March 10, 1975.
This invention relates to the conversion of installed single glazed windows into multiple glazed windows, more particularly - to an improved structure and method for affixing an additional pane of glass and a spacer element to an existing window installation so as to create a double glazed unit having a hermetically sealed, insulating airspace between the panes.
Although it has long been recognized that double glazed windows possess much greater insulating ability than single glazed windows, most installations have been provided with single glazing for the sake of economizing on construction costs. But with the rapid rise of the costs of heating and cooling buildings, this economy has proven to be false. Thus, it has become increasingly desirable to convert single glazing to double glazing, not only for improving the insulating ~-properties, but also for the sake of the advantages attained from the addition of a tinted or reflectively coated pane. Unfortunately, remov-ing and discarding existing windows and installing whole double glazed t units in their place incurs prohibitive costs for labor and materials.
. ~ccordingly, it is an object of this invention to provide ::
a method and means for quickly and easily converting a single glazed ; 20 window into a double glazed window by sealing an additional pane ofglass to the existing installation. The present invention is specifi-cally adapted to provide easy installation, ready adaptability to any size of window opening or frame construction, superior moisture barrier integrity, and improved structural strength.
Various attempts have been made in the prior art to provide on-site installation of secondary panes of glass, but all suffer from certain shortcomings that have discouraged their use. A typical prior art approach can be seen in United States Patent No. 2,436,037 (Doney) where a rubber gasket serves as both spacer and sealing means.
The rubber-to-glass seal utilized therein is a relatively poor moisture - 1 - ~

~056Z17 .

barrier, since most natural and $ynthetic rubbers are somewhat pervious, thus rendering the sur~aces of the airspace susceptible to condensation.
Rubber is also susceptible to degradation upon exposure to sunlight and weather conditions. Such an arrangement is limited to installation from the outside on relatively deep frames, a distinct disadvantage at many locations, especially on large bulldings. ~urthermore, sealing diffi-culties would be encountered at the mitered corner joints called for in Doney. Another prior art approach is shown in United States Patent No.
3,299,591 (Woelk) where a strip of epoxy resin serves as both spacer and sealant. That arrangement provides only a short barrier against ., , moisture penetration, and the epoxy resin, which is apparently required for the sake of high adhesion strength and room temperature curability, . is not a reliable sealing material because of its moisture vapor trans-missibility and low temperature inflexibility. In order to obtain an attractive appearance, it also appears that specialized extruding or casting equipment for the epoxy would have to be employed at the instal-lation site. A further prior art approach is disclosed in United States Patent No. 3,573,149 (Tibble et al). In that patent, a neoprene compo-sition is melted and cured in situ to effect a seal. Again, the barrier in the path of moisture penetration is short in length, and the curable thermoplastic material required is not noted for its moisture barrier ,; properties. Installation requires the use of specialized electrical equipment at the site and lengthy heating times. The technique is also susceptible to uneven heating which may, in turn, yield uneven sealing.
Add-on glazing devices of a different type can also be seen in the following four United States Patents relating to automobile windows:

1,777,435 .......... Hogelund 1,915,098 .......... Kile 1,945,742 .......... Hilger

2,098,127 .......... Auger .~

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: lOS6217 :-' -~ Each of these references suffers ~rom lack of permanency and inte~rity o seal, which are requlred Por acceptance in the architectural glazing field. Each employs an unprotected organic spacer which is subject to moisture penetration.
Thus, according to the invention, there is provided an architectural glazing unit for converting installed glazing to multiple . .
glazing which comprises no more than one transparent pane and a spacer .
element adjoining marginal portions of a major surface of said pane around the perimeter thereof and spaced from the peripheral edges of the pane. A body of at least partially uncurred polymeric sealant is adhered to said major surface of said pane between the spacer element and the ;~ peripheral edges of the pane around the perimeter thereof. The sealant has a dimension normal to the aforesaid major surface which is greater than that of the spacer element. The sealant also has a moisture vapor ; transmittance of less than about 15 grams of water per 24 hours per square meter for one mil thickness and at room temperature, is coherent and tacky but flowable under pressure.
The invention also provides a method of increasing the insulating value of a vision opening in a building wall structure glazed : 20 with an installed transparent pane, which method utilizes the glazing unit described above. More particularly, such method comprises the following steps:
: applying a spacer element onto marginal portions of a major surface of an additional transparent pane around the perimeter of said additional pane, and, spacing said spacer element from peripheral ` edges of said addition pane;
adhering a body of sealant to said major surface of said additional pane between said spacer element and the peripheral edges of -~ said additional pane, said body of sealant being applied with a thickness in the direction normal to said major surface greater than that of said

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1056;~7 .spacer element, said sealant being compri~ed o~ an at least partially uncured polymeric composition having a moisture vapor transmittance of ; at least 15 grams of water per 24 hours per square meter for 1 mil thickness and which, at room temperature, is coherent and tacky but : flowable under pressure;
. aligning said subassembly in a generally parallel rela-:...
. tionship to a major surface of the installed pane, with said spacer element and said sealant disposed between said panes; and ` biasing the additional pane toward the installed pane " 10 to contact said major surface of the installed pane with said body of sealant and applying a compressive force on said body of sealant until ., the sealant flows and forms a resilient structural bond and a hermetic seal between said panes.
: The invention will now be described further by way of . example only and with reference to the accompanying drawings,wherein:
,., . Figure 1 is a perspective interior view, partially cut r'l away, of a typical single glazed window installation upon which the ~ present invention may be practiced;
,1 Figure 2 is a cross-sectional view of an edge strip ,. 20 assembly having an organic spacer and sealant material applied to a : moisture resistant ribbon in accordance with a related construction to that of the present invention;
Figure 3 is a cross-sectional view of an alternate embodiment of the edge strip assembly;
Figure 4 is a fragmentary cross-sectional view of the edge strip shown in Figure 2 applied to the periphery of a pane of glass . to form a subassembly;
Figure 5 is a fragmentary cross-sectional view of the subassembly shown in Figure 4 with sealant material applied thereto;
Figure 6 is a cross-sectional view of the subassembly shown in Figure 5 in a packaged form for handling and shipping;

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~ Figure 7 is a crDss~sectional view of the subassembly shown in Figure 5 in an alternate packaged form.
Figure 8 is a perspective lnterior view, partially broken away, of the window structure shown in Figure l after conversion to double glazing in accordance with one embodiment a related construction to that of the present invention;
Figure 9 ~s a fragmentary cross-sectional view, taken . along lines 9-9 in Figure 8 of a completed installation of the sub-: assembly shown in Figure 4 onto a previously single glazed window;
Figure lO is a fragmentary elevation of a subassembly :
. mounted onto an existing glazing installation showing one means for .`` vacuuming the airspace;
. Figure 11 is a fragmentary elevation of a subassembly having a vacuuming tube placed in a ~oint;
Figure 12 is a schematic, fragmentary, cross-sectional :
view of an alternate framing treatment for a narrow window frame in con-; junction with the present invention;
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Figure 13 is a schematic, fragmentary, cross-sectional view of an alternate framing treatment for a wide window frame;
Figure 14 is a schematic, fragmentary, cross-sectional view of an alternate framing treatment using a nail-less, screw-less trim insert;
Figure 15 is a fragmentary cross-sectional view of an alternate subassembly embodiment utilizing a rigid spacer;
Figure 16 is a fragmentary cross-sectional view of a completed installation of the subassembly shown in Figure 15 onto a previously single glazed window;
Figure 17 is an exploded, fragmentary, cross-sectional view of another related construction showing the relationship of the parts prior to assembly;

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~ Figu~e 18 is a fragmenta~y~ cross~sectional view of a ; completed installation of the embodiment of Figure 17;
Figure 19 ls a fragmentary cross-sectional view of another ~ subassembly embodiment which has a moisture barrier of sealants only;
"! Figures 20, 21 and 22 are fragmentary cross-sectional views of variations of the subassembly embodiment shown in Figure 19;
` Figure 23 is a fragmentary cross-sectional view of a - simplified subassembly embodiment employing a metal spacer; and Figure 24 is a fragmentary cross-sectional view of yet another subassembly embodiment which provides an organic spacer with a , moisture resistant wrapper.
The drawing figures which specifically relate to this ~i particular invention are Figures 21 and 22. However, the remaining ~- drawing figures are of assistance in understanding the concept of the ;~ invention and various related constructions.
Depicted in Figure 1 is an interior view of a single glazed window unit that would typically form part of a buildlng wall structure, the window comprising a pane of glass 15 and a frame 16.
The conversion of such a window to double glazing will serve as an illu-strative example of this invention.
In Figure 2, there can be seen a cross-sectional view of a preferred embodiment of an edge strip arrangement which forms an alternative construction to the present invention. The edge strip includes as a base element a continuous ribbon of moisture resistant (essentially moisture impermeable) material 20, preferably an aluminum foil or strip having a thickness of about 8 mils. Although somewhat more susceptible to moisture penetration, various films of plastic, such as the dense polyethylenes, may be used for the ribbon 20. A
continuous length of organic spacer element 21 is affixed along the length of the ribbon by means of an adhesive layer 22. Adhesive 22 may ' t be a sealant material, but ~s selected with st~ong adhesion as the primary desideratum so ~s to prevent dislocation of the flexible organic spacer in the completed installation. The adhesive 22 should be rigid ; in the temperature range encountered ln window installations, and or ease of manufacturing, it should be capable of forming an instant bond between the foil and the spacer. An adhesive that has been found suitable is USM 1311, a polyethylene copolymer sold by United States Machinery Corporation, which is applied in a hot melt form to the foil which is also heated. Such an adhesive forms an exceptionally strong 10 bond after the adhesive has cooled and set, the 180 degree peel strength ; between the spacer and the ribbon exceeding 25 pounds per lineal inch as determined by A. S. T. M. D-903-49T.
The expressions "moisture resistant", "barrier against . moisture penetration", and "hermetic seal", as used herein, refer to an ability to prevent passage of water vapor to such an extent that the sub~ect material or structure is capable of being utilized in a multiple glazed architectural installation. To qualify for such architectural use, a material or structure should present enough of an obstacle to water vapor transmission to preclude condensation of water vapor in the 20 interior of a multiple glazed unit at temperatures down to about 0F.
(i.e., about 1.77 x 10 grams of water per cubic inch of air in the unit) and preferably lower, over a period of several years. The time period required is at least about three to about five years, but preferably is at least about ten years, and in optimum cases is at least about twenty years. The amount of water vapor penetration depends not only on the inherent moisture vapor transmission of the material employed as the obstacle, but also on the dimensions (e.g., thickness) of the obstacle in the path of water vapor penetration. Because visual aesthetics must be considered in regard to architectural glazing, it is desirable to minimize the dimensions of the water vapor barriers, thus materials having , a relatively low moisture vapor transmission are preferred. For this reason, it is generally preferred that the materials used for moisture barriers in multiple glazing have a moisture vapor transmission of less than about 15 grams (preferably less than about 6 grams) per 24 hours per square meter per mil thickness at 100F. and 90% relative humidity as determined by A. S. T. M. E-96-66E. Desiccants are often included in multiple glaæed units to adsorb moisture vapor in the airspace, and when a desiccant is employed, the requirements for moisture barriers may be relaxed by an amount corresponding to the water adsorbing capacity 10 of the desiccant.
Referring again to ~igure 2, spacer 21 may be any solid or semisolid rubber or synthetic polymeric material which maintains sufficient rigidity under ambient temperature conditions to retain two panes of glass in substantially parallel, spaced relationship. A pre-.... .
;i` ferred spacer is the spacer-dehydrator disclosed in United States Patent No. 3,758,996, which may be described generally as a moisture vapor transmittable matrix of a block copolymer of styrene and butadiene having interspersed therein a desiccating material. If such a spacer-dehydrator .; is not used, separate desiccating material is preferably affixed to or ; 20 embedded in at least a portion of the spacer along its length or placed in the airspace at the time of installation - at the site.
~ As shown in ~igure 2, a continuous band of mastic 23 is ; applied to ribbon 20 parallel to spacer 21. The composition and width of mastic 23 are selected so as to form a moisture resistant barrier when bonded to the glass surface, as will be set forth with more particularity hereinbelow. Mastic 23 is desirably a room temperature curable or vulcanizable material that will cold flow to form a moisture resistant seal and a resilient structural bond. Butyl-based mastics are preferred, such as the two component, room temperature curable, butyl-based mastic disclosed in United States Patent No. 3,791,910 to George H. Bowser.

~ 1056Z17 On-site assembly is substantially expedited by providing a tacky, non-curing composition for mastic 23. A preferred non-curing mastic has the following composition:
(Component) (Weight %) polyisobutylene (viscosity average molecular w~ight75,00 - 100,000) 15 - 50 polyisobutylene (viscosity average molecular weight 8,000 - 10,000) 10 - 45 . carbon black 10 - 45 silica pigment 5 - 15 zirconium orthosilicate 5 - 15 l.,i polybutene 20 - 50 zinc oxide o - 5 gamma-glycidoxy-propyltrimethoxysilane O - 5 On an extending portion of ribbon 20, on the opposite side of spacer 21 from mastic 23, there is provided a band of adhesive 24. The primary function of adhesive 24 is to hold the extending portion of ribbon 20 against the side of spacer 21 when the ribbon is folded in accordance with assembly procedures to be set forth below. Thus, adhesive 24 may be merely a na.row bead or discontinuous spots of adhesive material. In most cases, however, band 24 may be the same compound as mastic 23. As an alternate embodiment fbr the edge strip, there may - be a single mastic-adhesive layer 25 applied to substantially the entire surface of one side of ribbon 20 as shown in Figure 3. Although the Figure 3 embodiment lacks the advantages of using the hot-melt adhesive 22 of the Figure 2 embodiment, it possesses sealing advantages in that the organic spacer 21 may be protected by a continuous layer of moisture resistance mastic. Mastic 25 may consist of the compositions disclosed in United States Patent No. 3,791,910 or the non-curing mastic composition set forth above.

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l~ Turning now to ~igure 4, there iS shown the edge st~ip li l ~`~ of ~igure 2 applied to ~ rigid trAnsparent pane 30, whlch is the addi-X tional pane to be added to the existing installatlon. ~ane 30 may be glass or plastic, and may be tinted or reflectively coated in accordance . with known methods in the art. ~hen the pane 30 is coated, especially when the coatings are sub~ect to deterioratlon, the coating should be ' on inner surface 31, which will ultimately be exposed to only a sealed airspace. Care must be taken to clean all oil, dirt, and other contami-.
nants from the pane using approprlate solvents. Glass panes may also have :
i.... 10 their edges lightly seamed to reduce lacerative risk to personnel and to i~ prevent tearing of ribbon 20.
As shown in ~igure 4, the spacer 21 is placed with one ~: side in close contact with surface 31 of the pane. Sealant or adhesive may optionally be included between the spacer and the pane for extra ~ sealing or extra strength but is usually not needed. The extending - portion of ribbon 20, which carries mastic 23, ls folded around the edge of pane 30 and is pressed against the pane so as to flow the mastic and ~: create a seal between the ribbon and the peripheral edge 32 of the pane as well as to the margin of major surface 33. The other extending : 20 portion of the ribbon, carrying adhesive or mastic 24, is folded against j~ and adhered to the side of spacer 21 which is adjacent to the side already adhered to the ribbon. Generally, the attachment of the edge strip assembly is started at one corner of the pane and is continued about the entire periphery of the pane with a single length of the edge strip. At corners, the spacer may be notched to produce mitered joints.
Where the ends meet, the edge strip may be trimmed to butt the ends together and sealant added to the joint, or the spacer may be cut from an overlapping length of the edge strip and the extra length of ribbon 20 sealed across and beyond the joint.

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.~ 1056Z17 't"' Several important ~dyantages o~ the p~esence o ribbon .,~
` 20 can be seen at this point. First, a ~lexible organic spacer is given structural rigidity by reason of ;Lts attachment to the ribbon.
~; Also, a spacer, flexible or rigid, is thereby provided with a stronger structural attachment to pane 30. Another important advantage is that the presence of ribbon 20 permits the use of a greater width of moisture resistant material (sealant 23) for sealing the interface between the spacer and pane 30, and because the moisture resistant material is deployed between the ribbon and surfaces of pane 30 rather than between the spacer and the pane, it enables one to exert greater and more uniform - pressure on the material to form a good seal than could be dcne by attempting to press a flexible organic spacer itself onto the pane.
Furthermore, the ribbon provides a laterally and longitudinally continuous, ` moisture resistant barrier in the path of moisture penetration into a pervious organic spacer.
Optionally, a band of mastic 34 may be applied along the exposed surface of the portion of ribbon 20 which extends around the spacer and is parallel to the major surfaces of pane 30 as shown in ` Figure 5. Mastic 34 should be tacky and non-curing, preferably the butyl-based composition described above in connection with mastic 23, and may be conveniently supplied in strips on release paper. The release paper may be pressed in place to flow the mastic and to effect a seal and then peeled from the mastic. Mastic layer 34 should cover sub-stantially all of the surface of the aforesaid portion of the ribbon.
The addition of mastic 34 may be omitted without seriously affecting performance of the unit, but its presence has been found to result in the formation of a superior seal with a minimum amount of applied pressure.
The subassembly shown in Figure 5 is ready for mounting onto the existing glazing. The preceding fabrication of the subassembly v; 1056217 t may take place at a cent~Rl location and the subassemblies shipped to the ~ob site, or the fabrication may be performed at the site. When `~: the subassemblies are shipped in prefabricated form it is desirable to ~ ~, protect mastic 34 such as by retaining release paper 35 thereon as shown in Figure 6, or by providing a strippable overlay of sheet material 36 (Figure 7) over the entire open face of the subassembly. Overlay 36 not .:;
only protects mastic 34 but also maintains the cleanliness of the inner surface 31 of pane 30 and, if the overlay is a relatively impervious :.
material, preserves the desiccant that may be carried by the spacer and 0 protects the inner surface from moisture.
In Figure 8, the subassembly of Figure 5 is shown installed onto the interior of the existing single glazed window depicted in Figure l. Interior installation is advantageous for the sake of easy accessibility, but the present invention can also be used for adding glazing on the exterior side. Exterior installation may even be pre-~` ferred in some cases because o~ particular sash configurations or for better reflectivity when reflectively coated glass is being added.
Optional decorative trim 40 is also shown in Figure 8 applied around the periphery of the window. Details of the installation may be seen in Figure 9, which is a cross-sectional view of the edge portion of the window, taken along lines 9-9 ln Figure 8.
When installing the subassembly to surface 4I of existing pane 15, that surface and the adjacent areas of frame 16 must be .~ thoroughly cleaned. A layer of moisture resistant mastic 42 is then - applied around the periphery of pane 15 along a path corresponding ~, generally to the outline of spacer 21 on the subassembly as shown in Figure 9. The width of the layer 42 may be wide enough to extend at ; least slightly above and below the outline of the area that spacer 21 will contact on surface 41 so as to provide a maximum area of contact and some margin for error. Extending mastic 42 all the way to frame 16 ` ~:

` 1056217 will p~ovide an even greater ma~g~n fo~ error and expedite alignment of mastic 42 on surPace 41. ~ast~c 42 is tacky, preferably the non-curing, butyl-based sealant described above in rePerence to mastic 23, and may be carried on release paper which is pressed against the pane 15 and then peeled ofP. The combined thicknesses of mastic 34 and mastic 42 ` should be sufficient to assure a flowing of the mastic material when they are pressed together, thus eliminating voids and effecting a continuous hermetic seal. It has been ~ound satisPactory to provide mastics 34 and 42 each with thickness of about one-sixteenth of an inch, or, when mastic 34 is not employed, to provide mastic 42 alone with a thickness of about one-eighth of an inch.
The subassembly is next moved into position and aligned with mastic 42. Setting blocks oP a resilient material such as neoprene are inserted at spaced intervals across the bottom edge of the sub-assembly in the space between the subassembly and frame 16 in accordance ` with conventional glazing technlques. The subassembly is then pressed against pane 15 to effect a seal with mastic 42. Pressure may be applied by clamp means carried by the glass holding equipment, or by special ~ leverage means coacting with the Prame or wall structure, Another technique is to impose a vacuum ln the newly-created air space 43 for a sufficient time to permit the mastic to Plow and seal. Both vacuum and mechanical means may be used simultaneously to obtain the best results.
The vacuum may be attained by inserting a hollow needle 47 through ribbon 20 and spacer 21 as shown in Figure 10 if space permits, and afterwards sealing the puncture. In most cases, however, it is preferable to seal a length of flexible, small-gauge plastic tubing 48 into the joint of the edge strip during fabrication of the subassembly as shown in Figure 11 so as to communicate the air space with the exterior.
After the vacuum has been drawn by way of the tubing and held for a period of time, the vacuum is released and the tubing sealed or the tube .

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removed and the aperture sealed. In some cases, it is desirable to include a breather tube in double glazed units as disclosed in United States Patent No. 3,771,276. In such cases, the breather tube may be used to pull the vacuum in the airspace.
At this point in the assembling procedure, the resulting double glazed unit is essentially complete. As an extra precaution, it may be desirable to extrude a sealant 44 into the gap left around the perimeter of the unit. Resilient butyl-, polysulfide-, or silicone-based sealants may be used for this purpose. Such a sealant may also be appropriately filled or colored so as to serve as a decorative trim.
For the sake of appearance, it may also be desired to fasten metal, plastic, or wooden trim 40 to frame 16. Although the ribbon 20 and the :.
various mastic layers provide adequate strength in themselves for hold-:
ing the resulting double glazed unit together, the trim 40 may also be .
adapted to provide a secondary restralnlng force.
-~ The add-on multiple glazing technique of the present invention can be adapted for use with virtually any window frame con-figuration. Two such adaptations are shown in Figures 12 and 13.
Figure 12 depicts schematically a completed installation on a relatively 20 narrow frame 16a utilizing a modifled trim member 40a. Figure 13 is a `~ schematic representation of a completed installation involving a rela-;.
tively wide frame 16b and modified trlm 40b. In cases where extremely narrow frames are encountered, it may be necessary to fasten additional strips of material to the frames to extend the width of the frames.
Another modification, shown in Figure 14 in connection with a schematic illustration of a completed installation, is the use of a nail-less, screw-less trim member 40c. Such a trim member is provided with an extending flange 45 which carries a plurality of barbs 46. The trim is installed by merely pressing the flange 45 into the sealant 44, where the outwardly oriented barbs will engage the sealant and resist removal.

~056Z17 Heretofo~e the descripti~n ~)f the invention has ~elated to the use of organic spacers, but alternatlve constructions may also employ metal spacers. In Fi~ure 15~ there is shown a subassembly embodi-ment which includes a rigid spacer 50, preferably made of metal, contaln-ing desiccant 51, and provided with an openlng 52. Details of a pre-ferred metal spacer are disclosed in United States ~atent No. 2,684,266.
Since metal spacers generally requlre welding at the corner ~oints, the unit shown in Figure 15 is contemplated as being primarily a factory fabricated item. As such, the mastic materials employed may be selected - 10 from any of the moisture resistant sealant compounds previously discussed, preferably the butyl-based sealants. Since the metal spacer forms a . rlgid structure, the mastics may be chosen primarily for their sealing characteristics rather than their structural strength properties.
Spacer 50 may be sealed to the addltlonal pane 15 by means of sealant 53 so as to form a primary hermetic seal. A moisture reslstant ribbon 54, (preferably metallic) coated with a sealant 55, is sealed to the outer surface of the spacer and folded around the edge of the pane 30 so as to form a moisture resistant seal with its peripheral edge surface 32 ; and with the margin of ma~or surface 33. The secondary seal thus formed and the primary seal at 53 together provide a superior moisture barrler.
-~ An adequate seal can be achieved with sealant 55 alone, thus sealant 53 could be eliminated if desired. Since a metal spacer such as spacer 50 is essentially moisture impervious, rlbbon 54 need not be extended over the ad~acent surface of the spacer as done in the organic spacer embodiments. The ribbon does serve another function, however, that belng reinforcement of the attachment of the spacer to the pane 30. ~or this reason, it may be advantageous to likewlse provide a ribbon o~
sufficient width to enable a portion to be folded around a corner of the spacer and to be adhered to the ad;~acent front surface of the spacer in the case of metal spacers as well.

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~ completed inst~llation of the subassembly of ~i~ure 15 onto a single glazed window may be seen in ~igure 16. ~lounting techniques are similar to those described above in connection with the organic spacer embodiments. Mastic layer 56 is pre~erably the same tacky, non-curing, butyl-based material previously described, and is applied to the glass 15 in the same manner as mastic 42 in the previous embodiments.
Prior to mounting, additional mastic may be applied to the exposed surface of spacer 50 which is parallel to the major surfaces of pane 30 in order to provide a mastic-to-mastic bond with layer 56.
- 10 The techniques of the present invention may also be applied to a method of attaching a metal spacer to an additional pane which may be carrier out at the job site without the need for welding.
Referring now to Figure 17, there is shown an unwelded segment of a metal spacer 60 having desiccant 61 and an opening 62. A separate segment is provided for each side of the unit, and each segment is individually affixed to additional pane 30 by means of adhesive or sealant layer 63 which is preferably tacky so as to form an instant bond. A continuous ribbon 64 of moisture resitant material (essentially moisture impermeable), preferably aluminum foil, having a layer of tacky, non-curing, moisture . .
resistant sealant 65 thereon, is then applied to the edge of the unit, folded around the edge of pane 30 and a corner of spacer 60 and pressed to flow the sealant and form a seal. Because the ribbon is passed con-tinuously around the corners of the unit, a good seal can be attained without requiring the joints of the metal spacer to be welded. The ends of the ribbon 64 should be overlapped to effect a seal.
The subassembly of Figure 17 is installed onto the existing glazing 15 as shown in Figure 18 with the same mounting pro-cedures as set forth above, the critical seal being effected by a tacky, non-curing mastic 66 that is similar to or the same as mastic 56.

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Having regard to the foregoing, it may be appreciated that subassemblies suitable for architectural use can be produced without peripheral ribbons, Examples of such embodiments may be seen in Figures 19 through 24.

,; , The subassembly shown in Figure 19 is essentially the same as the embodiment of Figure 4, except that the ribbon has been omitted, and in lieu thereof moisture resistance is provided by sealant layer 70 and structural strength is provided by adhesive layer 71. A barrier for resisting moisture penetration through organic spacer 21 or between the spacer and pane 30 is provided by select-ing appropriate materials and thicknesses for sealant 70. The preferred material ., - 10 for sealant 70, as well as for the sealants in Figures 20 through 22, is the pre-viously described tacky, non-curing, butyl-based composition. When such a tacky ; sealant is employed, it wouid be desirable to protect the exposed surfaces of the : .
sealants shown in Figures 19 through 22 during shipping and storage with suitable . strips of release paper.
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Adhesive 71 may be a moisture resistant material as well, or, as , shown in Figure 20, a continuous layer of moisture resistant sealant 72 may extend .
around three sides of the spacer, thereby serving as both moisture barrier and ` structural joining means.
- Figure 21 illustrates the present invention and depicts a two-layered approach, where an extra thick body of sealant 73 serves as a moisture barrier. This approach requires moisture ~o penetrate an exceptionally great thickness of moisture resistant sealant in the direction parallel to the major surfaces of pane 30 before it can enter spacer 21. The body of sealant 73 pro-trudes beyond the spacer so as to engage and form a seal with an installed pane ' ' ' . .
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10516~17 `. to which the subassembly is to be mounted, It may be noted that the spacer 21 '~ may be either of the types discussed in the foregoing description, i.e~ an . organic or a metalli~ spacer- since the primary sealing function is performed by the sealant 73. A greater area for sea:Ling a subassembly to an installed pane ., may be provided by employing an extended body of sealant 74 as shown in Figure 22.

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- 17a -~. 10C~6Z17 Since ~ spacer made o~ metal is itself moisture imper-vious, the need for a moisture resistant seal in an embodiment employing -- a metal spacer is primarily to reslst moisture penetration around the .
spacer. Thus, in Figure 23, a metal spacer 50, as described in connection with the Figure 15 embodiment, is sealed to pane 30 with a layer of - moisture resistant materlal 75. The metal spacer and the layer 75 to~
gether present a moisture resistant barrier in the path of moisture ; penetration in the direction parallel to the ma~or surfaces of pane 30.
,, The same approach may be utilized with a relatively moisture transmlttable organic spacer if the spacer is first made moisture resistant by wrapping - it with a moisture resistant tape 76 as shown in Figure 24. The tape is - held in place on spacer 21 with spots or beads of adhesive 77. Tape 76 is preferably an essentially moisture impermeable material such as an aluminum foil or strip.
The mounting procedures and the general configurations of the completed multiple glazed lnstallations for the subassembly embodiments of Figures 19 through 24 are essentially the same as set forth above in connection with the Figure 9 and Figure 16 embodiments.
It should be apparent that in any of the embodiments ; 20 disclosed herein a second subassembly may be lnstalled onto a previously mounted subassembly so as to create a triple glazed installation.
Alternatively, one subassembly itself may include two or more spaced panes.
Each of the sealants, mastics, or adhesives employed in conjunction with this invention is preferably highly moisture resistant, i.e., characterized by low moisture vapor permeability so as to effect good moisture barriers and hermetlc seals. In addition, they are also preferably characterlzed by excellent flexlbility; cohesive and adhesive bonding; and tear, shear, peel, and tensile strength ~ver a relatively wide range of expected operating temperatures, including temperatures ., .

' 10516Zl7 from ~60E to 140~F. Furthermore, they should be essentially inert and unaffected by chemicals, e.g., cleaning solutions, air borne pollutants ~' or the like, with which they may normally be expected to co~e into ~ . .
contact.
:
It should be understood, however, that in certain instances related to the location or use of the sealants, mastics, or adhesives in the structures disclosed, one or more of the above charac-teristics or properties may be of more dominant importance than another or others and accordingly, the choice of mastic materials used may vary substantially. For example, moisture resistance is not a dominant requirement for mastic 22 in the subassembly of ~igure 2 because ribbon 20 in conjunction with the other mastics can provide the desired pro-tection against moisture penetration during shipping, storage, or after final installation to form a multiple glazed window.
- Although the present invention has been described with particular reference to the specific details of certain embodiments thereof, it is not intended that such details shall be regarded as limitations upon the scope of the invention except insofar as included ~: in the accompanying claims.

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Claims (3)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An architectural glazing unit for converting installed glazing to multiple glazing, comprising:
no more than one transparent pane;
a spacer element adjoining marginal portions of a major surface of said pane around the perimeter of said pane and spaced from the peripheral edges of said pane; and a body of at least partially uncured polymeric sealant adhered to said major surface between said spacer element and the peripheral edges of said pane around the perimeter of said pane, said sealant having a dimension normal to said major surface greater than that of said spacer element, said sealant having a moisture vapor transmittance of less than about 15 grams of water per 24 hours per square meter for 1 mil thickness and which, at room temperature, is coherent and tacky but flowable under pressure.

2. The glazing unit of claim 1 wherein said spacer element is comprised of a flexible moisture vapor transmittable, polymeric material.

3. The glazing unit of claim 1 wherein said spacer element is rigid and is formed from metal.