Abstrict This invention relates generally to spacer assemblies for insulating
glass units. More specifically, this invention relates to a single
component desiccant matrix which can be applied to the interior
of a spacer assembly at room temperature. Upon exposure to the ambient
atmosphere, the desiccant matrix irreversibly cures.
Claims What is claimed is:
1. In an insulating glass unit wherein a first glazing pane is
maintained in a spaced apart relation with a second glazing pane
by a spacer so as to define an interior volume therebetween, the
improvement comprising:
a desiccant matrix disposed on said spacer and in communication
with said interior volume, said desiccant matrix comprising:
a powdered molecular sieve desiccant; and
a carrier for said powdered molecular sieve desiccant, said carrier
comprising an atmospheric curing resin which partially cures upon
exposure to a component of an ambient atmosphere selected from a
group consisting of moisture and oxygen, during assembly of said
insulating glass unit said resin fully curing after assembly of
said glass unit.
2. The desiccant matrix of claim 1 wherein said powdered molecular
sieve desiccant comprises approximately 40-70% by weight of said
desiccant matrix.
3. The desiccant matrix of claim 2 wherein said powdered molecular
sieve desiccant comprises approximately 60% by weight of said desiccant
matrix.
4. The desiccant matrix of claim 1 wherein said resin comprises
approximately 10-25% by weight of said desiccant matrix.
5. The desiccant matrix of claim 4 wherein said resin comprises
approximately 22% by weight of said desiccant matrix.
6. The desiccant matrix of claim 1 wherein said matrix further
comprises a plasticizer.
7. The plasticizer of claim 6 wherein said plasticizer comprises
approximately 0-30% by weight of said desiccant matrix.
8. The plasticizer of claim 7 wherein said plasticizer comprises
approximately 5-20% by weight of said desiccant matrix.
9. The plasticizer of claim 8 wherein said plasticizer comprises
approximately 13% by weight of said desiccant matrix.
10. The desiccant matrix of claim 6 wherein said plasticizer comprises
a low volatility, low vapor pressure plasticizer selected from the
group consisting of phthalate esters, chlorinated paraffins, silicon
oils, and mineral oils.
11. The desiccant matrix of claim 1 wherein said powdered molecular
sieve desiccant comprises approximately 30-80% by weight of said
desiccant matrix.
12. In an insulating glass unit wherein a first glazing pane is
maintained in a spaced apart relation with a second glazing pane
by a spacer so as to define an interior volume therebetween, the
improvement comprising:
a desiccant matrix disposed on said spacer and in communication
with said interior volume, said desiccant matrix comprising:
a powdered molecular sieve desiccant, wherein said powdered molecular
sieve desiccant comprises a desiccant selected from the group consisting
of synthetic zeolite, sodium aluminum silicate, potassium aluminate
silicate and mixtures thereof; and
a carrier for said powdered molecular sieve desiccant, said carrier
comprising an atmospheric curing resin which partially cures upon
exposure to a component of an ambient atmosphere selected from a
group consisting of moisture and oxygen, said resin fully curing
after assembly of said glass unit, said resin fully curing after
assembly of said glass unit, wherein said resin is selected from
the group of resins consisting of moisture curing urethanes, moisture
curing polysulfides, oxygen curing polysulfides and mixtures thereof.
13. The desiccant matrix of claim 12 wherein said powdered molecular
sieve desiccant comprises a blend of 3A and 13X desiccants.
14. The desiccant matrix of claim 12 wherein said moisture curing
urethane comprises an alkoxy silane terminated polyurethane.
15. The desiccant matrix of claim 12 wherein said resin comprises
an alkoxy silane terminated polyether.
16. The desiccant matrix of claim 12 wherein said resin comprises
a polydimethylsiloxane resin.
Description BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention relates generally to methods and compositions for
constructing insulating glass units and in particular, methods and
compositions for making a desiccant matrix which is applied to a
metal spacer assembly used in the construction of insulating glass
units. Most specifically, the present invention relates to a powdered
desiccant which is suspended in an atmospheric curing resin, the
resin being in a liquid phase at room temperature.
II. Description of the Prior Art
Insulating glass units generally comprise a pair of glass sheets
maintained in a spaced apart relationship to each other by a spacing
and sealing assembly which extends around the periphery of the inner,
facing surfaces of the glass sheets, to define a sealed and insulating
air space between the glass sheets. A spacer assembly generally
comprises an inner spacer-dehydrator element which extends around
the periphery of the inside facing surfaces of the glass sheets.
The inner surfaces of the glass sheets are attached to the outer
surface of the spacer assembly by means of a sealant or adhesive.
In one typical form of insulating glass unit, the inner spacer-dehydrator
element comprises a hollow metal spacer element generally adhered
to the periphery of the inside, facing surfaces of the sheets, to
provide an insulating air space. The metal spacer element is generally
tubular in shape and filled with a desiccant material, which is
put in communication with the insulating air space to absorb moisture
therefrom, and to enhance the performance and durability of the
unit. The desiccant prevents moisture condensation on the inner
surfaces of the window panes.
There are several known ways of filling the spacer assembly with
the desiccant material. One known way is to manually pour beads
which serve as carriers for the desiccant in the spacer assembly.
This method is unsatisfactory because it is both inefficient and
labor intensive. Another approach to applying the desiccant material
to the spacer assembly is to utilize a powdered molecular desiccant
which is carried in a hot melt butyl thermoplastic carrier. There
are numerous problems with this approach. Because the hot melt carrier
must be maintained at an elevated temperature while the desiccant
material is being applied to the spacer, this procedure requires
elevated temperature application equipment, thereby increasing initial
capital costs and operating costs. Additionally, since the desiccant
impregnated spacers often times must be handled right after application
of the desiccant material, the hot melt systems increase the likelihood
that operators of the equipment as well as handlers of the spacers
will get burned. Finally, the use of thermoplastic materials to
carry the powdered desiccant may compromise the aesthetic integrity
of the insulating glass unit in that even after installation, the
desiccant carrier can remelt and/or sag if the window unit is exposed
to elevated temperatures. This makes the use of thermoplastics as
desiccant carriers highly undesirable for window units installed
in locations having hot climates.
U.S. Pat. No. 4622249 discloses a silicone glazing adhesive/sealant
as a desiccant carrier. The carrier material is a flexible, organic,
room temperature vulcanizable adhesive sealant material comprised
of two components. One of the components comprises a base material
and the other component comprises a curing agent or accelerator.
Neither of the components is individually curable or vulcanizable.
When the two components are combined, a chemical cross linking reaction
takes place which begins curing or vulcanizing the two-component
material at room temperature.
U.S. Pat. No. 3758996 discloses a desiccant material which is
carried in a thermoplastic carrier. In one example, the desiccant
matrix is applied to the spacer assembly at a temperature above
250.degree. F.
The present invention overcomes all of the problems of the prior
art in that it provides a desiccant matrix for use in a spacer assembly
of an insulating glass unit which can be applied as a single component
and at
room temperature. Upon exposure to the atmosphere, the desiccant
matrix irreversibly cures into a solid structure, thereby preventing
the desiccant from running or sagging at some later date after installation
of the window unit. Since the desiccant matrix can be applied as
a single component and at room temperature, operating costs are
kept down, as well as minimizing the potential risk of injury to
workers who must handle the spacer assemblies. These and other advantages
of the present invention will be readily apparent from the description,
the discussion and examples which follow.
SUMMARY OF THE INVENTION
There is disclosed herein a spacer assembly for use in a multiple
pane window assembly comprising a powdered molecular sieve desiccant
suspended in an atmospheric curing resin which is a liquid at room
temperature. The composition of the desiccant matrix comprises,
by weight, approximately 30 to 80% of a powdered molecular sieve
desiccant, together with approximately 5 to 40% of an atmospheric
curing resin.
In particular embodiments, the powdered molecular sieve desiccant
has a pore size ranging from three angstroms to ten angstroms. The
desiccant may comprise a mixture of different pore-sized material.
One particularly preferred molecular sieve desiccant comprises a
blend of 97% 3A and 3% 13X desiccants. The liquid carrier is preferably
an atmospheric curing resin which exists in a liquid state at room
temperature. One particularly preferred group of atmospheric curing
resins comprises alkoxy silane terminated polyurethanes. Another
preferred group of resins comprises alkoxy silane terminated polyethers.
Finally, a third group of preferred resins comprises polydimethylsiloxanes.
The composition may also include ancillary ingredients such as plasticizers,
catalysts, and fillers. Some preferred plasticizers include phthalate
esters, chlorinated paraffins, mineral oils, and silicon oils. The
catalysts may include organotin compounds such as dibutyl tin dilaurate
and dibutyl tin diacetate, as well as aliphatic titanates and amines.
Small volume fillers may include colorants, rheological materials
and/or pigments.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a spacer assembly;
FIG. 2 is a cross-sectional view of a spacer assembly in an insulating
glass unit.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 and 2 the present invention is directed to
a spacer assembly 10 for use in a multiple pane window unit, the
interior of the spacer assembly 10 being filled with a desiccant
matrix 12. The desiccant matrix 12 can be applied to the spacer
14 at room temperature, and upon exposure to moisture and/or oxygen
is irreversibly cured.
In the broadest sense, the present invention includes a powdered
molecular sieve desiccant which is dispersed in an atmospheric curing
resin which exists as a liquid at room temperature. Within the context
of this disclosure, atmospheric "curing resins" are meant
to include monomeric and low molecular weight polymeric materials
which cross-link and/or polymerize upon exposure to a component
of the ambient atmosphere, typically oxygen or water vapor.
Preferably, the powdered molecular sieve desiccant is present in
the desiccant matrix 12 in a concentration of 30 to 80% by weight,
more preferably 40-70% by weight, and most preferably 60% by weight.
The liquid carrier is typically present in the desiccant matrix
12 in a range of 5 to 40% by weight, more preferably 10-25% by weight,
and most preferably 22.2% by weight. The carrier further comprises
atmospheric curing resins which exist in a liquid phase at room
temperature. The desiccant matrix 12 may also include a catalyst,
a plasticizer, as well as small volume fillers.
The powdered molecular sieve desiccant is preferably one which
has a pore size ranging from three to ten angstroms, and mixtures
thereof. It may further comprise synthetic zeolite, sodium aluminum
silicate, or potassium aluminum silicate. Among some of the more
preferred desiccants are powdered molecular sieve 3A and powdered
molecular sieve 13X, as are known in the art. One particularly preferred
desiccant comprises a blend of 97% 3A and 3% 13X desiccants.
The carrier for the desiccant is an atmospheric curing resin which
exists in the liquid phase at room temperature. A preferable group
of carriers for the desiccant comprises moisture cure polyurethanes,
moisture cure polysulfides, polydimethylsiloxanes, and oxygen cure
polysulfides. Some specific carriers include alkoxy acetoxy oxyamino
silane terminated polyethers and polyether urethanes; alkyl siloxane
polymers crosslinked with alkoxy acetoxy oxyamino organo functional
silanes; moisture curable isocyanate functional poly oxyalkaline
polymers and polyalkaline polymers; thiol functional polymers and
oligomers (such as polyethers, polyether urethanes, polysulfides,
polythioethers), suitably catalyzed to produce moisture curable
systems; epoxide functional polymers and oligomers with moisture
deblockable crosslinkers; and acrylic function polymers with deblockable
crosslinkers. Most preferably, the carrier comprises alkoxy silane
terminated polyurethanes, alkoxy silane terminated polyethers, or
polydimethylsiloxane polymers. In one preferred formulation, the
carrier comprises Kaneka MS, manufactured by KaneKagafuchi Chemical
Company of Japan and distributed by Union Carbide. In a most preferred
formulation, the carrier comprises Permapol MS, manufactured by
Courtaulds Coatings, Inc.
The specific organic catalyst used in the present invention will
depend upon the particular carrier which is used. Preferable catalysts
comprise organotin compounds, aliphatic titanates (having from one
to twelve carbon atoms) such as lower alkyl *titanates, and amines.
Most preferably the catalyst comprises dibutyl tin dilaurate, dibutyl
tin diacetate, tetrabutyl titanate, and tetraethyl titanate.
The selection of the plasticizer is also dependent upon the nature
of the liquid resin. The most preferable plasticizers are phthalate
esters, chlorinated paraffins, mineral oils, and silicone oils.
The selection of the plasticizer depends upon compatibility with
the liquid resin, low cost, as well as having low volatility and
low vapor pressure. A plasticizer having high volatility or high
vapor pressure would be undesirable because it would fog the interior
of the insulating glass unit. In a preferred formulation, the plasticizer
comprises 0-30% by weight of the desiccant matrix 12 more preferably
5-20% by weight, and most preferably 13.4% by weight.
Although the material will still cure without the addition of the
catalyst, the addition of a catalyst provides for very rapid skin
times, as well as faster curing times, which may be necessary in
certain situations. It may also be desirable, in some instances,
to add small amounts of fillers, colorants, pigments, rheological
agents and the like.
The desiccant matrix 12 of the present invention may be prepared
in the following manner. Preferably, the plasticizer is first disposed
in a mixing vessel. In one preferred embodiment, the mixing vessel
comprises a variable speed, multishaft unit, having a low speed
sweep blade, a high speed disperser, and a low speed auger. The
mixing vessel further comprises a 300 gallon, triple shaft vacuum
mixer with cooling capabilities. The liquid polymer is then added
to the plasticizer and mixing begins at low speed. Thereafter, the
powdered molecular sieve desiccant is added to the mixture and the
high speed disperser is activated to decrease the average particle
size of the mixture as well as to increase uniformity within the
mixture. At the point the desiccant is added, the mixing is conducted
under vacuum so as to eliminate any exposure of the mixture to moisture.
The fillers, colorants and the like, as well as the catalyst, are
added last. The material is maintained under essentially dry conditions
until such time as it is ready to be applied to the spacer assembly
10.
The desiccant matrix 12 is applied to the interior of the spacer
assembly 10 at room temperature. The application can be made by
any conventional dispensing technique such as extruding, pumping,
or the like. Upon exposure to the atmosphere, the desiccant matrix
12 irreversibly cures. Upon installation, the spacer assembly 10
is disposed between a plurality of glass sheets 16. The spacer assembly
10 is adhered to the glass sheets 16 by means of a conventional
sealant 18 as is known in the art. The final curing of the desiccant
matrix 12 generally takes place once the entire insulating glass
unit 20 is installed. |