Static structures (e.g. – buildings) – Composite prefabricated panel including adjunctive means – Sandwich or hollow with sheet-like facing members
Reexamination Certificate
1999-09-17
2001-10-16
Cuomo, Peter M. (Department: 3636)
Static structures (e.g., buildings)
Composite prefabricated panel including adjunctive means
Sandwich or hollow with sheet-like facing members
C428S034000
Reexamination Certificate
active
06301858
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to an insulating glass unit and, in particular, to a moisture impervious sealant system for an insulating glass unit and a method of making same.
2. Description of the Currently Available Technology
It is well recognized that insulating glass (IG) units reduce the heat transfer between the outside and inside of a building or other structure. Examples of IG units are disclosed in U.S. Pat. Nos. 4,193,236; 4,464,874; 5,088,258; and 5,106,663 and European reference EP 65510, the teachings of which are herein incorporated by reference. A sealant system or edge seal structure of the prior art is shown in FIG.
1
. The IG unit
10
of
FIG. 1
includes two spaced apart glass sheets
12
and
13
adhesively bonded to a rigid spacer frame
14
by a sealant system
15
to provide a chamber
16
between the two glass sheets
12
and
13
. The chamber
16
can be filled with a selected atmosphere, such as argon or krypton gas, to enhance the performance characteristics of the IG unit
10
. The sealant system
15
bonding the glass sheets
12
and
13
to the spacer frame
14
are expected to provide structural strength to maintain the unity of the IG unit
10
and prevent gas leaking out of the chamber
16
or the atmosphere from outside the IG unit
10
from moving into the chamber
16
. The sealant system
15
includes a layer
17
of moisture resistant sealant at the upper section of the spacer
14
to prevent the ingress and egress of gas into and out of the chamber
16
and a layer
18
of a structural type sealant, such as silicone to secure the sheets to the spacer. A moisture resistant sealant usually used in the art is polyisobutylene (PIB).
In addition to adhering the two glass sheets
12
and
13
to the spacer frame
14
and forming a moisture impervious barrier, the sealant system
15
should accommodate the natural tendency for the edges of the glass sheets
12
and
13
to rotate or flex due to changes in atmospheric pressure in the chamber
16
as a result of temperature, wind load and altitude changes, such as when an IG unit is manufactured at one altitude and installed at a different altitude. The spacer and selected sealant system should maintain the structural integrity of the IG unit as well as the sealing properties of the edge seal structure even during such changes.
As will be appreciated, box spacer frames
14
, such as shown in
FIG. 1
, are not well suited for allowing such flexibility. For example and with reference to
FIG. 2
, as the distance between the sheets
12
and
13
increases because of pressure differences inside and outside of the chamber
16
, the sealant system
15
, in particular the layer
17
of the moisture resistant sealant, stretches and thins under stress, which decreases its ability to prevent atmospheric air from moving into and/or gas escape from the chamber
16
. With rigid, box spacer frames, the structural sealant system
15
tends to become over stressed with time and fails prematurely. Additionally, the rigid spacer frame itself may become over-stressed and may collapse or deform or the glass sheets may become over-stressed at the edges and crack. Further, if the chamber between the glass sheets is filled with gas such as argon, krypton or other such insulating gas, the deformation of the sealants
17
and
18
and/or spacer frame
14
often results in accelerated loss of those gases from the chamber into the surrounding atmosphere.
An alternative to the prior art arrangement shown in
FIG. 1
is to use a more flexible spacer frame, e.g. of the type disclosed in U.S. Pat. Nos. 5,655,282; 5,675,944; 5,177,916; 5,255,481; 5,351,451; 5,501,013; and 5,761,946, the teachings of which are herein incorporated by reference. While such flexible spacer frames help alleviate some of the problems encountered with rigid spacer frames, the use of flexible spacer frames in and of themselves may not completely eliminate the edge breakage and vapor and/or gas transmission problems associated with known edge seal and/or IG unit construction.
Therefore, it would be advantageous to provide an IG unit having a sealant system which reduces or eliminates the problems associated with known spacer frame and adhesive construction and a method of fabricating such an IG unit.
SUMMARY OF THE INVENTION
An insulating glass unit is provided having a first glass sheet spaced from a second glass sheet by a spacer frame. The spacer frame, preferably a flexible spacer frame, has a first side and a second side, with the first side located adjacent an inner-surface of the first glass sheet and the second side located adjacent the inner-surface of the second glass sheet. A sealant system incorporating features of the invention is provided on each side of the spacer frame to hold the glass sheets to the spacer frame. The sealant system includes a first structural sealant, preferably a thermosetting material, spaced from a second structural sealant, such as another or the same thermosetting material. A moisture barrier or moisture impervious material, preferably a thermoplastic material such as PIB, is located between the first and second structural sealant materials.
A method is also provided for making and using the sealant system of the invention for an insulating glass unit. A spacer frame is provided between a pair of glass sheets to provide a chamber therebetween. The spacer frame is preferably a flexible spacer frame fabricated by bending or forming a spacer stock. The spacer frame has a base and two spaced apart legs joined to the base to provide a substantially U-shape. The sealant system is applied to the spacer frame, e.g. beads of sealant material are provided onto the outer surfaces of the spacer frame, e.g. onto the outer surfaces of the legs and optionally onto the outer surface of the base. The sealant system includes a bead of low moisture vapor transmission or moisture barrier material, e.g., a thermoplastic material such as polyisobutylene or hot melt butyl, located between two beads of structural sealant, e.g., a thermoset material such as a silicone containing adhesive. The glass sheets are secured to the spacer frame by the sealant system.
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Cuomo Peter M.
Lepiane Donald C.
PPG Industries Ohio Inc.
Tran Hanh V.
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