Note: Descriptions are shown in the official language in which they were submitted.
1333 ~
2 7211~-10
1. Field of Inventlon
Thls lnventlon relates to lnsulatlng multlple layer
sealed unlts for the bulldlng envelope lncorporatlng lnsulatlng
spacers therefor and where the multlple layers are typlcally made
from transparent glazlng materlals.
2. DescrlPtlon of the Prlor Art
Insulatlng glass unlts generally conslst of two or more
parallel sheets of glass whlch are spaced apart from each other
and whlch have the space between the panes sealed along the perl-
pherles of the panes to enclose an alr space between them. Spacerbars are placed along the perlphery of the space between the two
panes. These spacer bars are typlcally long hollow perforated
metal sectlons, usually made from an alumlnum alloy and fabrlcated
elther ln the form of an extrusion or by rolllng from flat strlp
materlal. The hollow lnterlor of the spacer contalns a deslccant
materlal whlch ls used to absorb any resldual molsture that may be
ln the enclosed alr and to soak up any addltlonal molsture that
may enter lnto the sealed unlt over a perlod of tlme. The spacers
are assembled lnto a generally rectangular-shaped frame typlcally
uslng corner keys.
Unlts are constructed uslng elther a slngle or dual
seal. For slngle seal unlts, the structural, alr and molsture
vapour seal ls comblned ln one seal. Sealant materlals typlcally
used wlth slngle seal deslgn lnclude elther thermoplastlc sealants
such as butyl or thermosettlng sealants such as polysulphlde and
polyurethane. In general, the thermosettlng sealants are more
permeable to molsture vapour than the thermoplastlc sealants.
~ 1 ~ 3 ~ ~ ? J 1
3 72112-10
For dual seal units, there 18 an lnner seal, as well as
the maln outer seal wlth the inner seal generally functlonlng as
an addltlonal molsture vapour seal. Typlcally, for dual seal
unlts, the lnner seal ls a thermoplastlc materlal such as polylso-
butylene and a bead of the polylsobutylene 18 attached to the
sldes of the spacer ad~acent to the glass sheets. The spacer
frame ls then placed between the panes and heat and/or pressure 18
applled to ensure that the polylsobutylene ls compressed and fully --
wets out to the surface of the glass. For the second outer seal,
typlcally a thermc-settlng sealant such as slllcone or polysulphlde
18 used and 18 applled ln the outward faclng perlmeter channel
between the two glass sheets.
For sealed unlts conventlonally manufactured uslng cor-
ner keys, about 50 per cent of the molsture vapour enterlng the
sealed unlt ls through the corner connectlons. Slmllarly, for
sealed unlts fllled wlth low-conductlve gas about 50 per cent of
the gas 1088 from the sealed unlts 18 through the corner connec-
tlons. To lmprove the durablllty of sealed unlts, the corner
connectlons can be ellmlnated and the metal spacer bar can be bent
or stretch-formed around the corners. To complete the bent-corner
spacer frame, the two ends of the metal spacer can be welded or -
brazed together. Wlth the lntroductlon of automated equlpment,
bent-corner spacer frames can be very efflclently fabrlcated.
One problem wlth conventlonal sealed glazlng unlts 18
that because the alumlnum spacer 18 hlghly conductlve there 18 a
thermal brldge between the glazlng layers and thls can cause
perlmeter mlstln~ or lce bulld-up under extreme weather condl-
tlons. The metal spacer also causes glass stress, especlally wlth
~ .
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133~ $~J~
4 72112-10
low-e coated glass. On cold, sunny days the centre of the lnter-
lor glass heats up and expands but the materlal ls constralned by
the cold perlmeter glass, creatlng stress ln the glass. Under
extreme condltlons thls stress can be sufflclent to cause glass
breakage. These problems related to the use of a conductlve metal
spacer are now becomlng more slgnlflcant wlth the lntroductlon of
hlgh thermal performance glazlng. Compared to conventlonal double
glazlng (R-2 centre glazlng), hlgh thermal performance unlts range
ln performance from R-4 to R-12 (centre glazlng). Thls lncrease
ln thermal performance ls achleved through varlous comblnations of
low-e coatlngs, low-conductlve gas flll and addltlonal glazlng
layers.
For hlgh thermal performance glazlng, one optlon ls for
the low-e coatlng to be applled to a heat shrlnkable fllm whlch ls
lncorporated wlthln two outer glazlng layers. The method of manu-
facturlng thls type of sealed glazlng unlt ls descrlbed ln U.S.
Patent 4,335,166. A partlcular productlon problem ls that ln
order to avold corner wrlnkllng of the fllm followlng the heat
shrlnklng process, steel spacers are used ln preference to aluml-
num because of the hlgher stlffness and rlgldlty of the steelspacer.
Partlcularly ln bulldlngs where there ls a hlgh rlsk of
vandallsm, plastlc sheets may be used lnstead of glass ln the -
manufacture of the sealed unlts. The beneflts of uslng plastlc
lnstead of glass are lmproved securlty, reduced malntenance costs
and lncreased safety wlth no threat of glass breakage.
The maln drawback of uslng plastlc lnstead of glass ls
early fallure of the sealed unlt whlch ls caused by two maln -~
s*.. . . . . . . ~ -. :
1~ 3 ~
72112-10
factors. One cause 18 lncreased molsture bulld-up and deslccant
degradatlon resultlng from the comparatlvely hlgh permeablllty of
the plastlc glazlng materlal. A second cause 18 premature seal
fallure resultlng from the lncreased expanslon of the glazlng
layers due to the hlgher coefflclent of expanslon of the plastlc
glazlng materlal. A further drawback 18 that because of the
bulld-up of mol~ture wlthln the sealed unlt, hlgh performance low-
e coatlngs cannot be typlcally lncorporated lnto sealed plastlc
glazlng unlts because these coatlngs wlll degrade rapldly. Slml-
larly, because of the permeablllty of the glazlng materlal, low-
conductlve gas flll cannot be lncorporated wlthln the sealed glaz-
lng unlt, because over tlme the gas wlll dlffuse out of the unlt.
For hlgh securlty glazlng, lamlnated sheets of glass and
plastlc are used. However, because of the hlgher coefflclent of
expanslon of the plastlc, the plastlc sheets are typlcally lamlna-
ted between two glass sheets ln order to evenly constraln the
plastlc sheets and help prevent delamlnatlon of the glazlng
layers.
Although most multlple glazed unlts lncorporate conven-
tlonal metal hollow proflle spacers, there are other more speclal-
lzed types and deslgns of sealed unlts lncorporatlng metal spa-
cers. Two partlcular speclallzed deslgns of sealed unlts are
hlghllghted. -
One speclallzed deslgn of a sealed glazlng unlt whlch 18
used for ~tructural spacer glazlng lncorporates a metal channel-
shaped spacer whlch 18 used ln comblnatlon wlth a deformable seal- i--~
ant tape, contalnlng deslccant. The two legs of the spacer are
separately bonded to the glazlng layers wlth structural slllcone
~ ~-
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6 72112-10
sealant. The deslgn of structural spacer glazing unlts ls des-
crlbed ln detall ln U.S. Patent 4,552,790.
An lnterestlng appllcatlon of structural ~pacer glazlng
18 for flush glazed, openable wlndows. Wlth thls type of wlndow
deslgn, there ls no need for a separate sash frame and the openlng
wlndow hardware, weatherstrlpplng and related components are dl-
rectly flxed to the sealed unlt. A key advantage of thls type of
deslgn for hlgh thermal performance glazlng ls that wlthout the
supportlng frame, there ls lncreased energy efflclency. Flrst,
there are hlgher ~olar galns through the lncreased glazlng area.
Second, there are lower heat losses through the reduced perlmeter
frame area. A partlcular problem of uslng a metal spacer for
flush glazed wlndows 18 that holes cannot be drllled ln the metal
spacer as the metal spacer functlons as a molsture barrler and the
lntegrlty of the molsture vapour barrler must be retalned ln order
to malntaln the lntegrlty of the edge seal. Consequently, lt 18
comparatlvely dlfflcult to flx the dlfferent wlndow components
such as hlnges and openlng hardware to the sealed unlt.
A second speclallzed deslgn of sealed unlt 13 manufac-
tured wlth a contlnuous strlp product whlch comblnes spacer and ~ -
sealant ln a slngle product. The metal spacer 18 a flat metal
strlp bent ln a contlnuous zlgzag proflle whlch 18 embedded wlthln -~ -
an elongated rlbbon of deformable sealant contalnlng deslccant.
The product whlch 18 descrlbed ln U.S. patent 4,431,691 by
Greènlee 18 marketed commerclally under the name of Swlggle Strlp~
by Tremco Inc. of Cleveland, Ohlo.
As wlth conventlonal sealed unlts, the maln problem of
uslng metal spacers for these speclallzed deslgns 18 that the
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7 72112-10
highly conductlve metal spacer acts as a thermal brldge creatlng
heat loss and condensatlon around the lnner perlmeter of the seal-
ed unlt. Agaln as wlth conventlonal unlts, thls problem of perl-
meter edge heat loss ls now becomlng more slgnlflcant wlth the
lntroductlon of hlgh thermal performance glazlng unlts.
In order to address this problem of perimeter edge heat
loss, varlous efforts have been made over the past twenty years to
use lower conductlve plastlc materlals lnstead of metals for manu-
facturlng the spacer bar. However, these efforts to substltute
conventlonal thermoplastlc materlals have not proved to be suc-
cessful as plastlcs are generally unsultable as materlals for
manufacturlng spacer bars. The maln drawbacks of conventlonal
plastlc materlals lnclude: hlgh coefflclent of thermal expanslon,
poor UV stabillty, hlgh molsture vapour and gas transmlsslon, low
rlgldlty or stlffness, poor thermal stablllty wlth volatlle out-
gasslng and stress relaxatlon etc.
In order to overcome these drawbacks wlth conventlonal
thermoplastlc materlals, more complex deslgns for the spacer have
been developed uslng relnforced englneerlng grade plastlc materl-
als. One approach documented ln U.S. Patent 4,479,988 uses a
glass flbre fllled polycarbonate extruslon. The advantage ls that
the coefflclent of expanslon of the glass flbre fllled polycarbo- "'~'r~
nate ls somewhat reduced, however, the coefflclent of expanslon ls
stlll hlgher than glass.
Another approach documented ln U.S. Patent 4,551,364 and
ln U.S. Patent 4,564,540 uses a fibreglass pultruslon. Agaln, the
advantage ls that the coefflclent of expanslon of pultruded flbre
~ r~~
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:
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1333 ~
7a 72112-10
glass ls reduced and ln thls case ls almost the same as the co-
efflclent of thermal expanslon of glass.
These efforts to develop relnforced plastlc spacers have
not at present proved to be commerclally successful. There
appears to be flve main factors that account for the lack of
commerclal success of relnforced plastlc spacer bars.
One factor ls that the costs of manufacturlng relnforced
plastlc spacers are comparatlvely hlgh for both the extruded and
puitruded spacers. For the extruded spacer, productlon and
materlal costs are hlgh because each spacer ls lndlvldually ex-
truded uslng englneerlng grade plastlc reslns fllled wlth glass
flbres and because of the glass flbre flll, the extru lon dles
have to be replaced at regular lntervals. For the pultruded
spacer, the costs of settlng up to manufacture a speclflc proflle
are high. In addition, the walls of the pultruded proflle are
relatively thick and contain a high percentage of glass fibre - -
content and as a result, the materlal costs are comparatively high -~-
and the dies again have to be replaced at regular intervals.
A second factor is that even with the glass fibre flll
reinforcement, the reinforced plastic materlals remaln compara-
tlvely permeable. Consequently, there ls the concern that over
tlme molsture vapour wlll permeate into the sealed unit through
the walls and corner connections of the plastic spacer frame and
in the long term, this transmission of moisture will cause desic- -~
cant degradation and eventual failure of the sealed unit. Thls -
problem is partlcularly signlficant where slllcone ls used as the
outer sealant ln manufacturing the sealed unit. Similarly for ~- ~
gas-filled units, there ls also a concern that the low-conductive ~ - -
1,, " ". ~ ." ,
1~3~.3~1
7b 72112-10
gas wlll permeate through the plastlc spacer and over tlme thls
will result ln reduced thermal performance.
A third factor ls that reinforced plastlc spacers can
cause lncreased sealant stres~ and thls lncreased stress can
result ln premature
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8 72112-10
failure of the sealed unit. For the extruded reinforced spacer,
the increased sealant stress is due to the fact that the
coefficient of expanslon of the $1bre filled polycarbonate ls
higher than the coefflclent of expanslon of the glass. Por the
pultruded spacer so~e sealed unlt manufacturers conslder that
there is lncreased sealant stress due to the extre~e rlgldlty and
stlffness of the thlck wall spacer proflle.
A fourth factor ls that relnforced plastlc spacers can create
productlon proble~s. For the extruded spacer, the thln cross-
sectlon wlth glass flbre flll ~eans that the spacer cannot be
easily thermally welded together if deslred. For the pultruded
spacer, the hlgh percentage of glass flbre flll means that very
hlgh dust levels are created when the spacer 1B cut wlth a saw.
The flne dust 1B dlfficult to clean off the spacers for clean
a~sevbly of sealed units.
A fifth factor is that for the extruded polycarbonate spacer, the
problen of volatile outgasslng at hlgh te-peratures ha~ not been
resolved and sealed unlts fabricated uslng the polycarbonate
spacer at present have dlfflculty passing certaln durablllty ;~
teseing requirenents for sealed unit6. ~-
SUHHARY OF THE INVENTION
The lnventlon provldes an lnsulatlng spacer for lnterposltlon
between at least flrst and ~econd glazlng layers of a ~ultlple-
pane sealed unlt, whlch spacer ls of a hlgh draw ratlo oriented -~
ther~oplastic poly~eric materlal which la more highly molecularly
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1~31~
9 72112-10
orlented in the dlrection of the length thereof and which is free
of reinforcing fibers, said material having a lower thermal
conductivity in the direction between sald flrst and second
glazing layers than a material whlch does not have such a high
draw ratio, belng sufficiently highly drawn for having a
coefficient of thermal expansion in the directlon of the length of
said spacer which substantially matches the thermal coefficient of
expansion of said glazing layers, have dead-bend properties,
having stiffness and rlgldity sufficlent to make a frame around
the sealed unit self supporting, having ultra-vlolet resistance,
and having moisturc vapor and gas permeability less than sald
material which doe~ not have such a high draw ratio.
By fabricating a multiple slazed sealed unit with an inæulating
,, " ,~,,
spacer made from oriented thermoplastic polymer materlal lt has
been found that the probleos with the prlor art have been
overcooe. In particular, it has been found that some of the
apparent drawbacks of using an oriented thermoplastic material for
manufacturing insulating spacers can be used to advantage ln the
design of the product.
Various methods can be used to manufacture the oriented
thermoplastic material and generally these methods involve some
way of drawing or stretching the isotropic material. ~his process
of drawing or stretching the thermoplastic material aligns or
orientates the molecular structure of the isotropic polymer and
results in a materlal wlth substantlally modified properties.
These Dodifled properties are anlsotroplc. The properties of the
1[)
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1331~1
9a 72112-10
materlal ln the dlrection of draw are very dlfferent from the
properties of the material perpendicular to the direction of draw.
The material propertles al~o vary significantly dependlng on the
type of polymer and in particular whether the polymer is
crystalline or amorphous in molecular structure. Generally, it i5
the more highly crystalline polymers that are most affected by the
process of orlentatlng the polymer structure. Further, ln
general, the hlgher the draw ratlo, the greater the degree of
~odiflcation of the physical propertles of the oriented
theraoplastic poly~er.
: ~ '.
For ln6ulating spacer~, the ~odified and iDproved propertie~ of
the oriented ther~oplastlc ~aterlal ~ake lt fea~lble to
oanufacture lnsulatlng spacers from conventlonal therooplastlc
oaterlals usually
133~
72112-10
wlthout the need for addltlonal relnforcement. The use of orl-
ented thermoplastlc materlal results ln four maln lmproVements.
One lmprovement ls hlgher strength and stlffness ln the
dlrectlon of draw. The advantage of these lmproved structural
propertles ls that wlthout the need for glass flbre reinforcement,
the proflle wall thlckness of the orlented thermoplastlc spacer
can be thin, lowering the cost and welght of the spacer and also
reducing conductive heat loss through the thin wall profiles. The
increased stiffness of the insulating spacer profiles also speeds
up the assembly process for the sealed unit as the spacer frame '~
can more easily be lald down on the glass so that the sldes of the
frame are parallel to the edges of glazing sheets.
A second improvement is enhanced resistance to ultra-
violet tUV) radiation degradatlon. The advantage of improved
weatherability is that for certaln types of thermoplastic materi-
als, there ls no need for a separate UV barrier and the front face
of the oriented plastic spacer will not dust or flake even after
prolonged exposure to sunlight. Also, colour fading of the plas-
tic materlal wlll be reduced.
A thlrd improvement is enhanced high temperature stabil-
ity. One advantage of improved temperature resistance is that the
spacer is not deformed by the application of hot sealant during
the fabrlcatlon of the sealed unlt. A related issue is that the
lmproved thermal stabllity of the orlented thermoplastlc materlal
helps prevent outgasslng at elevated temperatures whlch causes
fogglng of the sealed unlt due to volatlle plastlc materlals con-
denslng on the lnner cold surfaces of the glass. The lmproved
.~ .
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11 72112-10
thermal stablllty of the materlal also ellmlnates the problem of
stress relaxatlon.
A fourth lmprovement ls enhanced barrler propertles.
The advantage of a lower rate of molsture vapour transmlsslon ls
that wlthout the need for a separate barrler coatlng, certaln
types of orlented plastlc materlals have the necessary barrler
propertles to ensure long term performance for the sealed unlt.
Slmllarly, the enhanced barrler propertles of the orlented thermo-
plastlc materlal help reduce the loss of low-conductlve gas from
the sealed unlt.
As well 8S these lmproved propertles, the process of
produclng the orlented spacer also results ln modlfled materlal
propertles that are not on thelr face, apparently advantageous or ~ -
compatlble wlth the requlrements of an lnsulated spacer for sealed -~
glazlng unlts.
One such property ls that the thermal conductlvlty
parallel to the dlrectlon of draw ls lncreased. The conductlvlty
perpendlcular to the dlrectlon of draw, however, ls somewhat de-
creased. We have found that by ensurlng that the dlrectlon of ~-
orlentatlon ls located largely ln the longltudlnal axls of the
spacer, advantage can be taken of the lower conductlvlty perpen-
dlcular to the dlrectlon of draw wlth the result that heat loss
across the edge seal ls reduced.
A second property whlch ls a consldered drawback, ls
negatlve thermal expanslon along the draw dlrectlon. For an
lnsulsted spacer, ln order to avold sealant stress, the coefflc-
lent of thermal expanslon of the polymer materlal should substan- -
tlally match the coefflclent of posltlve expanslon of the glass
~ 3 ~
12 72112-10
wlthln the temperature range of -30C to +60C. Our research has
shown that thls problem of negatlve expanslon can be overcome and
the coefflclent of expanslon ln the longltudlnal axls can be flne
tuned to match the coefflclent of expanslon of glass.
A third property whlch ls a consldered drawback ls that
the polymerlc orlented materlal ln the dlrectlon of draw exhlblts ;
dead bend propertles. Llke a metal, the materlal can be dented on
lmpact. For an lnsulated spacer, however, advantage can be taken
of thls "nulsance" property. One example ls where the spacer
frame ls fabrlcatecl by cold formlng or bendlng the spacer bar
around the corners or partly cuttlng or V notchlng the spacer and
then bendlng the spacer bar around the corners. The advantages of
the bent-corner spacer frame are, more efflclent assembly of the
sealed unlt partlcularly wlth automated productlon methods and
lmproved durabillty of the sealed unlt wlth reduced molsture
vapour transmlsslon and low-conductlve gas loss at the corners.
The process of manufacturlng the orlented plastlc sheets
or proflles does not alter other key propertles of the polymer
materlal that makes thermoplastlc materlals more sultable than
metals as materlals for manufacturlng spacer bars. These lmproved
propertles lnclude: llght welght, no corroslon, weldable, ease of
handllng etc.
The property of the orlented thermoplastlc spacer belng
weldable ls partlcularly advantageous for three reasons. Flrst,
ln the fabrlcatlon of a bent-corner spacer frame, lt ls easy to
weld the flnal ~olnt connectlng the two ends of the spacer bar.
Second, wlth gas fllllng the unlts, lt ls easy to seal up the
holes after the nozzles of the gas fllllng equlpment are removed.
b'`.
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~ 331~ ~
13 72112-10
Thlrd, in the fabrlcatlon of sealed unlts lncorporatlng gla~s and
plastlc lamlnated glazlng sheets or plastlc glazlng sheets or
fllms, the thermoplastlc spacer can be bonded to the plastlc gla-
zlng materlal.
Accordlng to a feature of the present lnventlon, the
sealed unlt can lncorporate sealant wetted out and adherlng to the
spacer and to at least one or both of the glazlng layers dependlng ;~ ~ ;
on the deslgn conflguratlon of the spacer. The sealed unlt can
also lncorporate addltlonal lnner glazlng layers arranged ln a
parallel and spaced relatlonshlp to the outer glazlng layers. The
glazlng layers can be glass sheets or thermoplastlc sheets or heat ;
shrlnkable plastlc fllms. Where thermoplastlc glazlng sheets or
fllms are used, the fllms or sheets can be bonded dlrectly to the
orlented thermoplastlc spacer. ~- -
Where the outer glazlng layers are plastlc sheets or
lamlnated sheets of glass and plastlc, the orlented thermoplastlc
spacer can be bonded around the perlphery of the outer glazlng -
sheets and no sealant ls necessary for the fabrlcatlon of the
sealed unlt.
For sealed plastlc glazlng unlts ln partlcular, the use
of the orlented plastlc spacer results ln substantlal lmprovements
ln the performance of the sealed unlt especlally where the outer
glazlng sheets are also made from transparent orlented thermo-
plastlc sheet materlal.
Flrst, the fabrlcatlon of the glazlng unlt ls slmpllfled
because there ls no need for outer sealant. Second, the durablll-
ty of the sealed plastlc glazlng unlt ls lmproved because of the
enhanced barrler propertles of the orlented thermoplastlc polymer.
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14 72112-10
Third, the heat 1088 through the edge seal 18 reduced a3 compared
to solld sealant, the thln walls of the orlented thermoplastlc
~ , ~" ,.,
spacer create a mlnlmal thermal brldge. Fourth, the energy efflc-
lency of the sealed plastlc glazlng unlt can be substantlally
lmproved as lt 18 feaslble because of the lmproved barrler proper-
tles of the plastlc glazlng to lncorporate low-e coatlngs and low-
conductlve gas flll. Also, because of the strength of the orl-
ented plastlc glazlng, lt 18 feaslble to fabrlcate thlck alr space
seeled unlts lncorporatlng multlple layers of low-e coated, heat
shrlnkable plastlc fllms. Compared to conventlonal double glazlng
~R-2) the thermal performance of these thlck alrspace, low-conduc-
tlve gas fllled, multlple-layer sealed plastlc glazlng unlts can
be ln excess of R-16. A partlcular advantage of uslng these hlgh
thermal performance, sealed plastlc qlazed unlts for openable,
f}ush glazed wlndows 18 that the varlous wlndow components such as
openinq hardware, hlnges and weatherstrlpplng csn be easlly bonded
to the orlented thermoplastlc glazlng and spacer.
For plastlc sealed glazlng unlts, the outer plastlc gla-
zlng sheets are typlcally manufactured from blaxlally orlented
thermoplastlc materlal or blaxlally orlented thermoplastlc materl-
al bonded to glass sheets. In contrast to conventlonal lamlnated
glazlng of glass and plastlc, the blaxlally orlented thermoplastlc
materlal does not have to be sandwlched between glass sheets as
the coefflclent of expanslon of the orlented thermoplastlc materl-
al can be flne-tuned to match the coefflclent of expanslon of
glass. The advantage 18 that the fabrlcatlon of the sealed unlt
ls slmpllfled as the orlented thermoplastlc sPacer can be bonded
~\ 7.~.
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72112-10
dlrectly to the lnward faclng plastlc layers of the lamlnated
glazlng sheets. -
In the fabricatlon of the spacer frame for the lnsulated
glazlng unlt, the orlented thermoplastlc spacer bars can be con-
ventlonally assembled lnto a generally rectangular-shaped frame
uslng corner keys. Alternatlvely, the spacer frame can be assem-
bled by cold formlng or bendlng the spacer bar around the corners
or partly cuttlng or V notchlng the spacer bar and then bendlng
the spacer bar around the corners. To complete the bent-corner
spacer frame, the two ends of the spacer bar can then be welded or
sealed together.
Conventlonal hollow proflle orlented thermoplastlc spa-
cers can be manufactured ln varlous ways lncludlng extrudlng the ~-
spacer as lndlvldual proflles wlth the materlal belng orlented as
part of the productlon process, or alternatlvely, roll-formlng the
spacer from flat strlps of already orlented thermoplastlc sheet
materlal. The orlented thermoplastlc materlal typlcally only
exhlblts lncreased dead bend propertles ln the dlrectlon of draw.
For the roll-formed spacer, ln addltlon to the need for orlenta- -
tlon ln the longltudlnal axls of the spacer, there ls also a need
for some degree of orlentatlon normal to the longltudlnal axls of
the spacer to allow roll-formlng as well as bendlng of the spacer
proflle. Thls blaxlal orlentatlon can be achleved ln varlous
ways, lncludlng. blaxlally orlentatlng the sheet durlng produc-
tlon or lamlnatlng two or more layers of orlented thermoplastlc
sheets together so that the dlrectlon of draw of one sheet ls
normal to the dlrectlon of draw of the other sheet.
~, . , : . ~ : -
t S ~
16 72112-10
The blaxlally orlented sheets may be manufactured uslng
a cross roll stretchlng process where the materlal ls orlentated
ln opposlng dlagonal dlrectlons to the longltudlnal axls of the
sheet materlal. In thls lnstance and wlth thls productlon method,
the requlred materlal propertles ln the longltudlnal axls of the
spacer can be achleved where the maln dlrectlon of orlentatlon may
not be largely ln a dlrectlon longltudlnal to the axls of the
spacer.
Generally ln the fabrlcatlon of the sealed unlt, the
hollow proflle spacer contalns deslccant and the slde of the spa-
cer facing the alrspace typlcally lncorporates perforated holes or
a slot so that the deslccant materlal can absorb molsture from the
alr wlthln the sealed unlt. Where the proflles are roll-formed,
one option ls for the edges of the plastlc sheet to be lntermlt-
tently thermally welded together creatlng a contlnuous but perfor-
ated seam on the slde of the spacer faclng the alrspace.
The spacer can be manufactured from dlfferent types of
thermoplastlc polymer materlals. One optlon where no sealant ls
used or alternatlvely where a very permeable outer sealant such as
slllcone ls used, ls to fabrlcate the spacer from a thermoplastlc
materlal whlch already has very good barrler propertles and fur-
ther lmprove these propertles through the process of orlentatlon.
One preferred materlal ls vlnylldene chlorlde (Saran~) and ln
additlon to lts very good barrler propertles, a further advantage
of uslng SaranN ls that all common types of sealant materlal ad-
here strongly to lt.
Dependlng on the type of thermoplastlc materlal used for
the spacer, the spacer may lncorporate a separate molsture vapour
~`
1 3 3 ~ ~ ~J ~
17 72112-10
fllm or coatlng or a separate UV barrier on the front face. Where
the spacer ls roll-formed from flat strlps cut from sheet materl-
al, the requlred coatlngs or fllms are flrst lamlnated or applled
to one or two surfaces of the sheet materlal. The hollow proflle
spacer ls then manufactured ln such a way that after the hollow
proflle spacer ls roll-formed, the coatlngs or fllms are located
on the approprlate surface of the spacer.
Varlous proflle deslgns of the orlented thermoplastlc
polymer spacer can be used for dlfferent speclallzed sealed gla-
zlng appllcatlons. One example ls where the spacer ls used forstructural spacer glazlng. A second example ls where the spacer
ls a contlnuous zlgzag bent flat strlp whlch ls embedded wlthln an
elongated rlbbon of deformable sealant contalnlng deslccant mater-
lal.
At present, bulldlng panels used as part of the bulldlng
envelope are not fabrlcated as multlple layer sealed unlts. How-
ever, because of the advances made ln developlng hlgh thermal per-
formance sealed glazlng unlts, there are now advantages ln uslng
the same edge seal technology developed for glazlng unlts for the
fabrlcatlon of opaque lnsulatlng panel~. These advantages of
uslng sealed opaque panels for the bulldlng envelope lncludel the
ease of future upgradlng of the thermal performance of the bulld-
lng envelope and the ease of malntalnlng and repalrlng the requlr- ~
ed alr barrler lncorporated wlthln the bulldlng envelope. These ; - ~-
panèls can provlde more lnsulatlon per unlt thlckness than con-
ventlonal lnsulatlon materlal~ used at present ln the bulldlng
envelope. The outer opaque layers used to manufacture these hlgh
thermal performance sealed panels can be made from a varlety of
~, : .
,~,~,
;,.i:
,, 1~3~ J~
18 72112-10
lmpermeable materlals lncludlng: thln stone or marble sheets
backed wlth metal or blaxlally orlented thermoplastlc sheets.
BRIEF DESCRIPTION OF DRAWINGS
The followlng ls a descrlptlon by way of example of
certaln embodlments of the present lnventlon, reference belng had
to the accompanylng drawlngs, ln whlch~
Flgure 1 shows a drawlng of a roll-formed orlented
thermoplastlc spacer,
Flgure 2 shows a detall ln cross-sectlon of a dual seal
double glazed unlt lncorporatlng an orlented thermoplastlc spacer;
Flgure 3 shows a detall ln cross-sectlon of a slngle
seal double glazed unlt lncorporatlng an orlented thermoplastlc
spacer;
Flgure 4 shows a detall ln cross-sectlon of a trlple
glazed unlt wlth an lnner flexlble, heat shrlnkable fllm sand-
wlched between two orlented thermoplastlc spacers;
Flgure 5 shows detall plan vlews of three alternatlve
corner constructlons of spacer frames manufactured from orlented
thermoplastlc polymers;
Flgure 6 shows a detall ln cross-sectlon of a trlple
glazed unlt lncorporatlng a heat shrlnkable fllm where the orl-
ented thermoplastlc spacers are dlrectly bonded to the glazlng
layers~
Flgure 7 shows a detall ln cross sectlon of a double
glazed unlt for structural spacer glazlng lncorporatlng a channel
shaped orlented thermoplastlc spacer1 and
~,
.
;~
- - : ,
: ~ :
133~
19 72112-10
Flgure 8 shows a corner detall of a double glazed unlt
lncorporatlng a deformable sealant edge seal wlth an orlented
thermoplastlc spacer strlp.
DETAIL~D DESCRIPTION
Flgure 1 shows a spacer 30A for multlple layer sealed
unlts whlch are used for such appllcatlons as wlndows. The lnsul-
atlng spacer ls of conventlonal cross sectlon but accordlng to the
lnventlon ls of orlented thermoplastlc materlal rather than metal,
conventlonal plastic or re-lnforced plastlc materlal.
There are essentlally two known methods for produclng
orlented polymerlc materlal. One method ls to produce an allgned
extended structure ln the polymer melt or solutlon whlch 18 fol-
lowed by or assoclated wlth crystalllzatlon whlch may lnvolve the
formatlon of a llquld crystal phase. A second method for produc-
lng orlented polymerlc materlal 18 based on the solld state de-
formatlon and concomltant orlentatlon of the orlentable thermo-
plastlc polymers. Solld-phase deformatlon processes lnclude.
extruslon drawlng, tenslle drawlng, hydrostatlc extruslon, ram
extruslon, die drawlng, and roll press stretchlng. Generally the ~ -
dlfferent processes lnvolve ln some way drawlng or stretchlng the
lsotroplc materlal. As an example, the speclflc technlque of dle
drawlng ls descrlbed ln U.K. Patent 2,060,469.
The present orlented thermoplastlc spacer ls typlcally
manufactured uslng solld-phase deformatlon processes. For solld-
phase deformatlon processes, the degree of orlentatlon ls largely
determlned by the draw ratlo although other factors such as tem-
perature, pressure and the type of productlon process also play a
X
~:r. ~
~33~
72112-10
role. The process of orlentating the lsotroplc materlal enhances
key propertles of the thermoplastlc polymer materlal and lt ls
these modlfled propertles that allow the lnsulatlng spacer to be
manufactured from commodlty or lntermedlate grade thermoplastlc
polymerlc materlals.
For an lnsulatlng spacer to functlon and perform satls-
factorlly wlthln a sealed glazlng unlt, a number of demandlng
materlal requlrements must be met. We have found that these
demandlng requlrements can be obtalned through controlllng the
degree and dlrectlons of orlentatlon of the molecular structure of
the thermoplastlc materlal from whlch the spacer ls made.
One requlred property for the lnsulatlng spacer 30A ls
strength and stlffness ln the longltudlnal axls of the spacer as
shown by arrow 34. In general, the hlgher the draw ratlo, the
greater the strength and stlffness of the material ln the draw
dlrectlon whlch should be parallel to the longltudlnal axls of the
spacer. However, compared to other uses of the ultra drawn orl-
ented thermoplastlcs, very hlgh draw ratlos are not necessarlly
requlred to manufacture an lnsulated spacer as the need for
strength and stlffness must be offset agalnst the other requlre-
ments of an lnsulated spacer.
A second property for an lnsulatlng spacer ls dlmen-
slonal stablllty ln the longltudlnal dlrectlon of the spacer as
shown by arrow 34. Partlcularly where the outer glazlng layers
are glass, the coefflclent of thermal expanslon of the orlented
thermoplastlc spacer should substantlally match the posltlve
coefflclent of expanslon of glass between the temperatures of
-30C to +60C.
. _ . . -- . . .
0 . ~
-: 13~Ull
21 72112-10
Generally, at hlgh draw ratlos, most crystalllne thermo-
plastlc materlals exhlblt a negatlve coefflclent of thermal expan-
slon. However, the negatlve coefflclent of thermal expanslon of
the orlented thermoplastlc materlal ln the draw dlrectlon can be
flne-tuned to match the posltlve coefflclent of thermal expanslon
of glass. Thls can be achleved ln three maln ways.
Flrst, the type of polymerlc materlal used has to be
carefully selected as the coefflclent of thermal expanslon varles
slgnlflcantly dependlng on the type of orlented thermoplastlc
materlal used. Materlals such as low denslty polyethylene have a
very hlgh rate of negatlve thermal expanslon whlle materlal such
as polypropylene have a lower rate. Second, the rate of negatlve
thermal expanslon lncreases wlth draw rates. At low draw rates,
the rate of thermal expanslon ls posltlve whlle at hlgh rates, the
rate becomes negatlve. Through careful optlmlzatlon, the coeffl-
clent of expanslon can be made slightly posltlve to agaln match ~-
the coefflclent of expanslon of glass. Thlrd, the coefflclent of
thermal expanslon can also be lncreased by anneallng the orlented
thermoplastlc materlal at hlgh temperatures.
A thlrd requlred property for an lnsulatlng spacer ls
low molsture vapour and gas permeablllty. Research has shown that
the permeablllty of orlented thermoplastlc materlal ls sensltlve
to draw ratlo. For example for polyethylene, the permeablllty of
the polymer ls reduced dramatlcally as the draw ratlo ls lncreased
from 5 to lO.
A fourth requlred property ls low conductlvlty normal to
the longltudlnal axls of the spacer (shown by arrow 33). Gener-
ally, the thermal conductlvlty of the orlented materlal normal to
133~
22 72112-10
the draw dlrectlon decreases with lncreaslng draw ratlo although
after a draw ratlo of about 5, lncreaslng the draw ratlo typlcally
does not result ln further substantlal reductlons ln thermal con-
ductlvlty.
Other requlred propertles lnclude thermal stablllty and
UV reslstance and, lt 18 found that these propertles are also en-
hanced by lncreaslng the draw ratlo.
Where the spacer 18 used to manufacture bent-corner
spacer frames a further requlred property ls that the spacer 30A
can be stretch formed or bent around the corners (see Flgure 5).
Through the approprlate control of draw ratlo and pro-
ductlon condltlons, and these optlmum ratlos and condltlons vary
by materlal type, a number of dlfferent types of thermoplastlc
materlals can provlde the requlred propertles for an lnsulatlng
spacer, lncludlng. polypropylene, hlgh denslty polyethylene and
polyethylene terephthalate.
Insulatlng hollow proflle spacers 30A as shown ln Flgure
l can be manufactured ln varlous ways lncludlng extrudlng the
spacer ln proflle form 80 that the materlal 18 orlented as part of
the productlon process or by roll-formlng the hollow proflle
spacer from flat strlps cut from sheet materlal whlch has been
prevlously orlented. The speclflc deslgn lllustrated ln Flgure 1
ls for a roll-formed spacer.
The hollow proflle spacer 30A ls roll-formed from flat
strlps of orlented thermoplastlc materlal uslng slmllar productlon
methods as are used to manufacture metal roll-formed spacers. As
shown ln Flgure 1 after the hollow proflle sectlon 18 roll-formed,
the two edges of the flat strlp of materlal are heat welded
~i
i'',,: - ` ' . ` - - . :
e -~
.: .:
3 ~
23 72112-10
together creatlng an lnvlslble seam 28 parallel to the longltudl-
nal axls of the spacer as shown by arrow 34. The seam 28 as shown
ln Flgure 1 ls on the backslde 31 of the spacer although alterna-
tlvely, the seam 28 can be located on one of the sldes 27 of the
spacer or on the front face 32 along the longltudlnal axls of the
spacer.
When lnstalled wlthln a sealed unlt, the spacer 30A
usually lncorporates deslccant materlal contalned wlthln the
hollow proflle. The deslccant materlal must be ln molsture com-
munlcatlon wlth the alr-space enclosed by the glazlng layer~. As
shown ln Flgure 1, one way that this can be achleved wlth elther
the extruded or roll-formed spacer ls by lncorporatlng perfora- -
tlons 29 on the front face 32 of the spacer 30A. A second way,
partlcularly for roll-formed spacers ls to lncorporate a contlnu- -
ous slot along the front face 32 of the spacer 30A. A thlrd way,
agaln partlcularly for roll-formed spacers, ls for the edges of
the orlented thermoplastlc sheet to be lntermlttently welded
together creatlng a contlnuous but perforated seam. Compared to a
continuous slot, the advantage of an lntermlttently welded slot ls --~-
a more rlgld proflle whlch allows the wall thlckness of the spacer
to be reduced.
Where the spacer ls roll-formed from flat strlps, lt ls
necessary that the sheet has dead bend propertles, both parallel
and normal to the longltudlnal axls of the spacer as shown by ~-
arrows 34 and 33. To achleve dead bend propertles ln two dlrec-
tlons typlcally requlres that the thermoplastlc materlal ls also
orlented ln at least two dlrectlons. Thls arrangement can be
achleved ln dlfferent ways.
~ '.
~ . .. , j, , ~ :
- ~ 33~
24 72112-10
One way ls to manufacture the strlps from orlented
thermoplastlc sheets where the materlal is orlented at least
blaxlally. The blaxlally orlented sheets may be manufactured
uslng a type of crossroll stretchlng process where the materlal ls
orlentated ln two opposlng dlagonal dlrectlons from the longltu-
dlnal axls of the spacer. It should be noted that by balanclng
the degree and dlrectlons of the orlentatlon of the sheet materlal
produced uslng the crossroll productlon process, the requlred
propertles of the spacer ln the longltudlnal axls can stlll be
achleved even though the maln dlrectlon and degree of orlentatlon
may not be largely ln the longltudlnal axls of the spacer as shown
by arrow 34.
A second way ls to cut the strlps from sheets of orlen-
ted thermoplastlc materlal whlch are lamlnated from at least two
layers. One of the layers may be orlented to a greater degree
than the other and the layer wlth the greater degree of orlenta-
tlon ls located so that the dlrectlon of draw ls parallel to the
longltudlnal axls of the spacer as shown by arrow 34. The second
sheet is located so that the dlrectlon of draw (as shown by arrow
33) ls normal to the longltudlnal axls of the spacer.
In roll-formlng the spacer from the lamlnated sheet
materlal, the flrst layer where the dlrectlon of orlentatlon ls
longltudlnal to the axls should become the outer surface on the
slde 27 of the spacer ad~acent to the glazlng layers (see Flgure
3~ and the second layer should become the lnner surface of the
spacer. Thls arrangement ls preferred as the layer wlth reduced
thermal conductlvlty on the outslde of the spacer 30A helps
,-~ . . -- ~ ~ , :-
1 3~
25 72112-10
prevent heat flow to the lnner layer with lncreased thermal con-
ductlvlty.
Although the process of orlentatlng the thermoplastlc
materlal generally lmproves the barrler propertles of the materl-
al, for certain appllcatlons where no outer sealant ls used or
alternatlvely where a very permeable outer sealant such as slll-
cone ls used, there ls a need to further lmprove the barrler
propertles of the spacer.
One way that the barrler propertles can be lmproved ls
to manufacture the spacer 30A from a thermoplastlc material which
already has very good barrier properties and further improve these
propertles through the process of orlentatlon. One preferred .
materlal ls polyvlnylldene chlorlde tSaran~) and ln addltlon to
lts very good barrler propertles, a further advantage of uslng
Saran~ ls that all common types of sealant materlal adhere strong- -
ly to lt. A second way that the barrier propertles can be improv-
ed ls to add a separate molsture vapour and gas barrler fllm or
coatlng to at least the back 31 and sldes 27 of the spacer 30A.
Compared to an extruded proflle, a particular advantage
of a roll-formed spacer 30A manufactured from strlps cut from -.
orlented thermoplastic sheets is that the sheets can be more easi-
ly lamlnated or coated wlth one or more layers of hlgh barrler
materlals. These hlgh performance barrler materlals and coatlngs
can lnclude, EVA, EVOH (Eval~), PVdC (saran~)~ and metalllsed
coatlngs on PET fllm.
In addltlon to the need for a separate barrler fllm or
coatlng there may al~o be a need wlth certaln types of plastlcs
~ , .
_ _. . .. - ~ .. .
133~8~J1
26 72112-10
for a ~eparate UV reslstant fllm or coatlng on the front face 32
of the spacer 30A.
Flgure 2 shows a dual seal unlt wlth an orlented thermo-
plastlc polymer spacer 30B. As wlth a conventlonal dual seal
unlt, beads of polylsobutylene sealant 36 are applled to the sldes
of the hollow proflle spacer 30B. The spacer 30B ls formed lnto a
spacer frame as wlll be explalned more fully herelnafter. The
preassembled spacer frame ls lnterposed between the flrst glazlng
layer 37A and the second glazlng layer 37B, ad~acent to the per-
lphery of the glazlng layers. Typlcally the orlentatlon of thepolymer materlal of the spacer 30B ls largely ln the longltudlnal
axls of the spacer.
Sealant 40A ls applled ln the outward faclng channel
around the perlphery of the glazlng sheets 37A and 37B. The
sealant 40A must adhere to the back 31 of the spacer 30B and for
certaln types of thermoplastic materlals, lt may be necessary to
treat or prlme the spacer 30B to ensure good adheslon. The spacer
30B contalns deslccant materlal 39 and typlcally lncorporates per-
foratlons 29 to allow airflow between the deslccant materlal 39
and the alr or low-conductlve gas 38 wlthin the ~ealed unlt.
Flgure 3 shows a cross-sectlon of a slngle seal, double
glazed unlt lncorporatlng a hollow proflle orlented thermoplastlc
spacer 30A. The outer sealant 40B can be any sealant wlth good
barrler propertles such as hot melt butyl, polysulphlde or poly-
urethane and so wlth thls ~deslgn because of the lower permeablllty
of the outer sealant 40B, there ls typlcally not the same need or
requlrement for the spacer 30A to be made from an orlented plastlc
X
. ~. . - .. ,., ~
~L~33 ~
27 72112-10
wlth outstanding barrler propertles or alternatlvely be coated
wlth a separate molsture vapour and gas barrler fllm or coatlng.
Flgure 4 shows a detall of a cross-sectlon of a trlple
glazed sealed unlt where two orlented thermoplastlc spacers 30C
support a heat shrlnkable plastlc fllm 51 between two parallel and
spaced apart glazlng sheets 37A and 37B. The heat shrlnkable
plastlc fllm 51 ls typlcally made from polyethylene terephthalate
(PET). The outer sealant 40C ls typlcally polyurethane sealant.
The sealed unlt ls generally manufactured uslng a known method
such as that outllned ln U.S. Patent 4,335,166. The partlcular
advantage of uslng orlented thermoplastlc polymer spacers 30C for
thls appllcatlon ls that the spacers can be as stlff and rlgld as
steel spacers used to date. A further advantage ls that the fllm
51 may be thermally bonded to the spacers 30C and thls can slmpll-
fy the assembly of multlple glazed unlts lncorporatlng heat
shrlnkable flexlble fllms.
Flgure S shows plan vlews of three alternatlve corner
detalls of spacer frames. In Flgure 5A, the two spacers 30A are
conventlonally ~olned wlth corner keys 42. In Flgure 5~, the
spacer 30E ls cold formed or bent around the corners 43 at room
temperature or at sllghtly elevated temperatures. In fabrlcatlng
the spacer frame from the orlented thermoplastlc hollow proflles,
slmllar equlpment to that used for corner bendlng metal spacers
can be used. The two ends of the rlgld plastlc spacer 30E can be
welded together as a butt ~olnt 45 to ensure a contlnuous molsture
vapour and gas barrler around the perlmeter of the sealed unlt.
Alternatlvely, as shown ln Flgure 5C, the spacer 50 can be par-
tlally cut and then bent around the corners 44. The speclflc
. '',.'
~r ~
- \
133~ ~5~
28 72112-10
corner detall shown ln Flgure 5C ls for structural spacer glazlng
(See Flgure 7).
Other alternatlve corner detalls of the spacer frames
not shown ln the drawlngs lnclude: thermally weldlng and seallng
the spacers together at the corners wlth a conventlonal mltre
~olnt and V notchlng the spacer and then bendlng the spacer around
the corner.
Flgure 6 shows a detall of a cross-sectlon of a trlple
glazed sealed unlt where two orlented thermoplastlc spacers 30G
10 support a heat shri.nkable fllm 51 between two parallel and spaced
apart glazlng sheets 52A and 52B. The glazlng sheets 52A and 52B
can be blaxlally orlented thermoplastlc polymerlc sheets or laml-
nated sheets from glass and blaxlally orlented thermoplastlc poly-
merlc materlal. Where lamlnated sheets are used, the orlented
thermoplastlc materlal ls on the slde of the glazlng faclng the
alrspaces 3QA and 38B. The hollow proflle spacers 30G contaln
deslccant materlal 39 and are bonded to the outer plastlc sheets
52A and 52B respectlvely as well as to the fllm 51 and to each
other.
Varlous processes can be used to dlrectly bond the
spacer to the plastlc glazlng sheets 52A and 52B lncludlng:
magnetlc heat seallng, adheslve bondlng, ultrasonlc seallng and
solvent weldlng. No outer sealant ls used and so the spacers 30G
must have a very low rate of molsture vapour and gas transmlsslon.
As explalned previously, thls can be achleved by elther manufac-
turlng the orlented thermoplastlc spacers from materlals such as
~lnylldene chlorlde whlch have very good barrler propertles or by
lncorporatlng a separate hlgh performance barrler layer.
~ 1
L'~
~ 3 ~
28a 72112-10
Slmllarly, for long term durablllty of the sealed unlt, the plas-
tlc glazlng sheets 52A and 52B must hsve a very low rate of
molsture vapour and gas transmlsslon and as wlth the spacer 30G
thls can agaln be achleved by elther manufacturlng the glazlng
sheet from an orlented thermoplastlc materlal whlch has very good
barrler propertles such as polyvlnylldene chlorlde or by lncor-
poratlng a separate transparent hlgh performance barrler layer.
As no outer sealant 18 used ln fabrlcatlng the spacer
frame, the corners must be hermetlcally sealed. Thls can be
achleved by elther manufacturlng the spacer frame uslng the bent-
corner method as descrlbed ln Flgure 5B or by assembllng the frame
from separate pleces and hermetlcally weldlng the corners. -
The blaxlally orlented thermoplastlc glazlng sheets 52
can be manufactured from varlous thermoplastlc materlals. In
addltlon to plastlc glazlng materlals such as polycarbonates or
acryllcs whlch are conventlonally used, other materlals such as
polypropylene and polyethylene may also be used as the process of
orlentatlng the materlal lmproves optlcal clarlty.
The sealed unlt ln Flgure 6 lncorporates a heat shrlnk-
able fllm 51, typlcally PET whlch 18 also bonded to the spacers30G. Although only a slngle fllm 51 18 shown ln Flgure 6, the
sealed unlt can lncorporate multlple parallel layers of heat
shrlnkable fllm. Super hlgh energy efflclent sealed unlts (R-18
centre glazlng) can be manufactured uslng low-e coated glazlng
sheets or heat shrlnkable flexlble fllms and fllllng the sealed
unlt wlth low-conductlve krypton gas flll whlch allows reduced
spaclng between the glazlng layers. For these thlck alrspace
sealed plastlc glazlng unlts, there 18 no concern of breakage
.. ,- ~ . ................................. ;. ,
~'`'' . - . : ' '
- . - - :
1333 ~
28b 72112-10
caused by pressure fluctuatlons wlthln the sealed unlt as the
outer glazlng sheets are made from essentlally unbreakable, rlgld
orlented thermoplastlc polymerlc material.
Where the plastlc sealed unlt ls used for flush glazed
openable wlndows, weatherstrlpplng, wlndow hardware and hlnges can
be dlrectly bonded to the plastlc glazlng and spacer. The unlt ls
self supportlng and there ls no need for a separate sash frame.
As a result, the cost of manufacturlng the flush glazed, openable
wlndow ls reduced.
Although the glazlng sheets 52A and 52B are typlcally
transparent, the layers may be translucent or opaque. Where the
sheets are opaque, one optlon ls to use lamlnated sheets made from
blaxlally orlented thermoplastlc materlal bonded to thln sheets of
stone or marble.
Dlfferent proflle deslgns of the orlented thermoplastlc
polymer spacer can be used for a wlde varlety of speclallzed
deslgns for sealed glazlng unlts. One speclallzed deslgn ls for
structural spacer glazlng.
Flgure 7 shows a detall of a cross-sectlon of an orlen-
ted thermoplastlc spacer 50 for a structural spacer glazlng unltwhere the spacer ls U shaped ln proflle creatlng a recessed chan-
nel 56 around the perlmeter of the sealed glazlng unlt. The
channel 56 ls partlally covered wlth a butyl tape 52 contalnlng
deslccant materlal. The spacer ls bonded to the glazlng sheets
37A and 37B wlth structural slllcone sealant 53. In addltlon to
reduced perlmeter heat loss, a partlcular advantage of uslng the
orlented thermoplastic spacer for thls appllcatlon ls that the
spacer frame can be very efflclently fabrlcated. As shown ln -
.
~,, .
G ~ ~ r ~ , , , ., ~ . ~. , ~ , ~ , ,, ~, , , ~ . . , . , :
1331~
28c 72112-10
Flgure 5C, the orlented thermoplastlc channel spacer ls partlally
cut through the back legs of the U channel and bent around at the
corners. The two ends of the channel spacer are then welded
together at a butt ~olnt creatlng a rlgld bent-corner frame.
Flgure 8 shows a detall drawlng of a second speciallzed
deslgn for the orlented thermoplastlc spacer whlch for thls appll-
catlon ls a spaclng element 55 lncorporated wlthln an edge seal
strlp product 57. The contlnuous spacer element 55 of undulatlng
shape ls embedded wlthln an elongated rlbbon of deformable sealant
contalnlng deslccant materlal. The edge seal strlp product 57 ls
placed around the perlphery of the glazlng layers 37A and 37B.
The orlented thermoplastlc material is used for the spaclng ele-
ment partlcularly because of lts dead bend propertles in the
longitudinal axis which allow the oriented material to be very
easily bent or folded creatlng the necessary zig-zag profile.
However, ln contrast to the conventional spacing element, the head
loss across the edge seal ln a direction normal to the longitu-
dlnal axls of the spacer is reduced.
The drawings descrlbed hereln illustrate only a very
small representative sample of some of the possible design con-
flguratlons for multlple-glazed sealed units lncorporating the
orlented thermoplastlc spacer bar.
Further, for the different sealed unit designs illustra-
ted herein, lt ls recommended for lmproved hlgh thermal perfor-
mance that the airspaces are filled wlth a low-conductive gas
flll, that one glazlng surface in each separate airspace is coated -~
with a high performance low-emissivity coatlng and where appropri-
ate a further glazing layer or layers may be incorporated between
., ~,.
~ 3
~, ~` ~ , . . .
t ~ " :: ~
~33~.8~Jl
28d 72112-10
the outer glazlng layers creatlng addltlonal alrspaces. To avold
repetltlon ln the descrlptlon of the drawlngs, speclflc reference
has not been made ln each case that the sealed unlts may lncorpor-
ate these features. It should also be noted that herelnbefore,
the space enclosed by the spacer and glazlng layers has been
referred to as an alrspace, and that thls speclflcally does not
exclude the posslblllty that the space may be fllled wlth an lnert
gas such as argon or alternatlvely, there may be no alr enclosed
and a partlal vacuum may be malntalned between the glazlng layers.
For good thermal performance, where alr or argon gas ls used, the
optlmum spaclng between the glazlng layers ls about 14 mm. Where
low-conductlve krypton gas ls used, the optlmum spaclng between
the glazlng layers ls reduced to about 7 mm.
