Note: Descriptions are shown in the official language in which they were submitted.
~049gl2
This application is related to our copending Canadian
application Serial Nos. 196,290 and 196,291, which were filed on
the same date as this case.
This invention relates to a fire-screenirlg glazing
panel comprising a fire screening means which becomes
operative when sufficiently heated.
In the construction of buildings, glazing panels
sometimes are used in exterior or interior walls or
partitions. An obvious example is the use of light_transmitt-
ing glazing panels used as windows.
Structural components occasionally must satisfystringent standards of fire resistance. Fire resistance is
sometimes quantified against a standard test in which
the structural component is exposed to a specified temperature
cycle over a certain period of time. The fire resistance
potential of the component depends on the length of time
for which the component can retain the strength required
for it to fulfill its function. To comply with some fire resist-
ance standards the component must have a minimum strength
retention time, must be completely flame-proof, and must pro-
vide enough thermal insulating power to ensure that the com-
ponent will prevent propagation of fire by heat radiation from
the component and will not become so hot as to result in
serious risk of burning a person who may touch the panel
while it is exposed to the fire. ~ -
2 -
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~fO499~
The standard of fire resistance of a given
component may be quantifled as a function 3f the tlme for
which the co~ponent satisfies one or more of the
speclfied criteria during a test in which the component
i3 exposed to the interior of an enclosure in which the
temperature is raised according to a predetermined schedule,
For example standards of fire resistance designated 1, 2
and 3 may be set corresponding to resistance times of
15, 30 and 60 minutes respectively in a test in which the
temperature of the test enclosure is 720, 820 and 925~C
respectively for each time period.
Ordinary panel~ comprising one or more sheets
of vitreous material are not highly thermally insulating
or fire resistant. When exposed to fire~ t~ey become
very hot so that they cannot be touched without causing
personal injury, Moreover heat radiation from the heated
panel itself constitutes a further fire hazard.
Various proposals have been made for dealing
with this problem, One proposal is to install in a
building having door and window openings sprinkler heads
for supplying a fire-extinguishing agent, e,g, water, The
sprinkler heads are placed above each door and window
opening of the build~ng and communicate with a common
reservoir containing the fire extinguishing agent, When
fire occurs, the sprinkler heads supply fire extinguishi~g
agent along the doors and windows, Such installations
have certain disadvantages, Among those disadvantages is
the ~act that the installations are complicated and can-
not be easily installed,
-3~
104991Z
It is an object of the invention to provide a fire-
screening glazing panel which can be easily and conveniently
handled and installed. It is a further object to provide such
a panel which has improved thermal insulating and fire-resisting
properties. In particular the invention seeks to provide a
panel which is resistant to mechanical breakage when subjected
to rapid heating by a heat source disposed on one side of the
panel.
The present invention as broadly defined resides
~0 in a fire-screening glazing panel comprising a fire-screening
means which becomes operative when sufficiently heated charac-
terized in that the panel comprises a first structural ply
formed by a vitreous sheet and at least one other structural
ply, and characterized in that between the said first structural
ply and the other or another structural ply there is sandwiched
at least one plastic membrane and, on opposite sides of said
membrane(s), layers, at least one of which is composed of at
least in part of material which when sufficiently heated is
converted to form a thermally insulating barrier or barriers
which is or are opaque or of greatly reduced infra-red radiation
transmitting power as compared with such layer before such
conversion.
Stated in other words, the invention resides in
fire screening panel comprising a first structural ply formed
by a vitreaous sheet and at least one other structural ply
formed by a vitreous or plastic sheet characterised in that
there is present at least one plastic membrane having on
opposite sides thereof a layer composed at least in part of a
material comprising a hydrated metal salt which when sufficien-
tly heated forms a solid porous or cellular body forming athermally insulating barrier said barrier forming layers and
b
.
, `~
~0499~2
and said plastic membrane being sandwiched between said first
and other structural ply.
The expression "Vitreous material" as used herein
comprises glass and vitrocrystalline rnaterial.
-4a-
10499~Z
V~trocrystalline material is formed by sub~ecting a glass
to a thermal treatment sc as to induce the formation of
one or more crystalline phases therein.
~lle invention a~fords a number oP advantages
which ar~ considered to be important.
~ first advantage is the fact that the ~ire-
screening ~lazing panel is very easy to install and is in
itself suf~icient to prevent or to delay the propagation
of f1re across an opening closed by the panel,
A second advantage i8 the fact that if the
panel is installed as part of a ~Jall of an enclosure in
which fire break~ out so that the plastic membrane is
disposed between the first structural ply and the interior
of said enclosure, the plastic membrane obviates or
reduces tendency for 1OCR1 over-heatin~ of the ~irst
ply to take place with consequent risk of breakage thereof,
The area which is immediately behind the plastic
membrane (the area occupied by that one of the sandwiched
layers which is nearer the fire) may become non-uniformly
heated due, for example, to the behavior of the material
of that layer on being heated and converted to form a
thermally insulating barrier. However tlle plastic
membrane will serve to ensure a more uni~orm distribution
of the heat transmitted to the sandwiched layer which is
in front of the membrane and to the first structural ply,
10499~
~ third advantage i6 that u~c3er t~le circumstance~
referred to, the tlme taken f`or the vltreous sheet
constituting the first ply to reach a given -temperature
is prolonged due to the presence of the membrane. The
vi~reous sheet can therefore provide the exterior face
of the panel which is exposed to touch, with less risk
of causing burns than would be involved in using a panel
of known constructlon and comparable weight.
As has been stated, at least one layer of
barrier forming substance is convertible by hea~ to form
a barrier which is of greatly reduced infra-red radiation
transmitting power, or which is opaque This feature
allows the formation of very effective f~re screens since
the intensity of any infra-red radiation from a fire on
~15 one side of the panel which is transmitted through the
panel may be reduced to a level at which it cannot,
of itself, start a secondary fire on the other side of
the panel.
It w~ll be appreciated that if the panel were
installed in reverse orientation to that above described,
i e.~ with the said first ply between the fire and the
plastic membrane, a corresponding advantage will be
achieved~ namely that the plastic membrane will slow
down the heating of the other face of the panel In
such a case that front face may be formed for example
by another vitreous sheet.
~0 49 9 ~Z
Tl~e lnvention ls equally applicable to
opaque panels and light-transmitting panels.
~le use oP opaque glazing panels, i.e~ panels
comprising one or more sheets of glass or vitrocryst~lline
material, is becoming increasingly important in
architecture and such panels are often used to form,
~or example, the lower part of a partition ~1hose upper
part is transparent, especially when it is desired that
t~e surface texture or some other property of the panels
forming the upper and lower parts of the partition be
similar. Preferably however, the panel is a light
transmitting panel, so that it may be used, for example,
as an observation window until the advent of fire.
Advantageously, the barrier forming material
i8 convertible by heat to form a solid porous or cellular
body, since such bodles generally have 10W thermal
conductivity.
Preferably, said barrier forming material
comprises an hydrated metal salt.
Examples of metal salts which can be used in
hydrated form are as ~ollows:
Aluminates, e g. sodium or potassium aluminate
Plumbates, e.g, sodium or potassium plumbate
Stannates, e g, sodium or potassium stannate
Alums, e g. sodium aluminum sulphate or
potassium aluminum sulphate
Borates e.g. sodium borate
Phosphates, e.g. sodium orthophosphates,
potassium orthophosphates and
aluminum phosphate
~049912
Hydrated alkali metal silicates, e g sodium
. ., _ ... ,~ ,.. .. .
silicate, ~re also suitable for use in a said layer
incorporating heat-convertible material
Such substsnces ha~e very good properties for
the present purposes. They are in many cases capable of
~orming transparent layers which adhere well to glass
or vitrocrystalline material. On being ~ufficiently
heated, the combined water boils and the layers foam,
80 that the hydrated metal salt i8 converted into an
opaque solid porous or cellular form in which it is
highly thermally insulating and remains adnerent to the
glass or vitrocrystalline material.
This feature is particularly important, since
even if all the structural plies of the panel are cracked
or broken by thermal shock, the panel may retain its
. ef~ectiveness as a barrier against heat and fumes since .
the fragments of the plies may remain in position bonded
together by the converted metal salt
If a panel according to the invention and
incorporating such hydrated metal salt sandwiched layers
i8 exposed to fire, the water in the salt layer which is
nearer the .~ire is first boiled off As this layer is
.~ heated the other hydrated metal salt layer is kept at a
somewhat lower temperature due to the presence o~ the
plastic membrane. During boiling off of the combined
water of the first sandwiched layer, its temperature
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1049912
remains substantially constant, and thermal conversion
of the fire screening material on the said other sand-
wiched layer is delayed. As the combined water becomes
completely removed from the sandwiched layer nearer the
fire this la~er be_omes er~ective as a thermal barrier.
In some embodiments, a layer of hydrated metal
salt is used which is merely translucent, but preferably
the hydrated metal salt forms a transparent solid layer
at ambient temperature. Sodium silicate, sodium aluminum
sulphate and aluminum phosphate can form transparent
layers.
It has been found that vitreous sheets may
suffer deterioration to varying degrees by prolonged
contact with various barrier-forming materials e.g. hydrated
metal salts. This is particularly important in the case
of transparent or colored sheets, since they may suffer a
loss of transparency or undergo a change in color.
Preferably, therefore, a protective stratum
, .
is provided between said first structural ply and the
2~ adjacent heat convertible layer said protective stratum
being formed so as to inhibit interaction between the
barrier forming rnaterial and the first structural ply.
. .
If the other structural ply is also a
. .
vitreous sheet, a protective stratum is preferably like-
~25 wise provided between that other vitreous sheet and the
ad~ecent leyer of barrier-forming meterial.
_ g _
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10499~Z
Thls feature is equally applic~ble in cases
where the panel is a true laminate, i,e, a multi-ply
panel wllose plies are bonded together face to face,
and where it is a multi-ply panel whose plie3 ~re held
clamped together by extraneous means, such as a frame.
In so~e preferred embodiments, the protective
stratum comprises a sheet of substantially water-
impervious plastic material. Polyvinyl butyral is an
especially suitable material for forming a plastic
protective stratum, which may for example be 0.76 mm
thick, though any other film-forming plastlcs material
having the requisite properties may be used.
In other preferred embodiments of the
invention there is at least one protective stratum which
comprises a coating applied to the vitreous sheet face
to be protected. Such a coating preferably comprises an
anhydrous metal compound deposited onto such sheet face,
since such coatings can form very effective protective
strata,
, 20 Clearly, one criterion affecting choice of a
suitable coating material will be the composition of the
thermally insulating barrier formin~-layer By way of
.
example when the barrier ~ rming material is of sodium
silicate~ ~r ~ or an~alumlof potassium or sodium, then
; 25 the coating material preferably comprises zirconium oxide
'~
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104991Z
or anhydrous a]uminum phosphate~ ~hen the thermally
insulatlng barrier formine layer is of hydrated alumlnum
phosphate, then titanium oxide, zlrconium oxide~ tin
; oxide and anhydrous alumlnum phosphate are eminently
suitable protective coating materials, It is, perhaps,
surprising to note that a protective stratum of anhydrous
aluminum pllosphate when deposited onto a vitreous sheet
will serve substantially to prevent interaction between
that vitreous sheet and an adjacent layer of hydrated
aluminum phosphatc, This invention does not exclude the
use of other coating materials,
. .. .. ..
Preferably the protective stratum when
constituted by a coating as aforesaid is between 100 and
1,030 Angstro~ units thick, so as to provide a non-
porous coating WitilOUt giving rise to unsightly inter-
ference effects.
Preferably, at least one said layer of barrier
forming n~terial is between 0.1 mm and 8 mm in thiclcness,
f~ Layers having this range of thickness can be converted
to become very effective fire-screening barriers. It
~ is clear that the effectiveness of a fire-screening
;~ barrier formed from a layer of given material will depend
on its thickness, however, the transparency of such a
layer will become less with increa~ed thickness,
Preferably at least one layer of heat-convertible material
has a thiclcness of between 0.1 and 0,5 mm.
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104~912
The plastic membrane or memblanes in a panel
accordlng to the invention can be ~ormed of any film-
f~rming pl~s~ic ma~erial havin~ tlle requis~te properties.
Preferably the panel incorporates at least one plastic
membrane composed of polyvinylbutyral, since this
material is especially suitable.
Polyurethane is also a very ~uit~le material
for forming st least one of said membranes, and indeed,
polyurethane is also suitable for forming a plastic
protective str~tum,
Preferably the first structural ply and/or
at least one other vitreous sheet (if present) of the
panel is tempered, A tempered vitreous sheet is better
able to withstand thermal shocks, Chemically tempered
sheets are particularly preferred,
A panel according to the invention preferably
comprises two structural plies, each constituted by a
vitreous sheet and each providing an external face of
the panel, Such a panel structure has a merit of simplifi ty,
It is to be understood however that it i9 within tl~e
scope of the invention for the panel to incorporate more
than two structural plies, The invention also includes
panels where a plastic membrane, together with layers of
, thermal barrier forming material on opposite sides of
; 25 the membrane, is present in each of the two or more inter- ply spaces,
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1(~4991Z
According to preferred embodiments of the
invention the panel is in the form of a laminate, i.e.,
a multi-ply panel structure in which the first vitreous
sheet, at least on~ other structural ply, a plastic
membrane between the plies and the heat convertible layers
on opposite sides of the membrane are bonded together in face
to face relation.
The invention however also includes multi-ply
panels in which the first ply, another structural ply,
a plastic membrane intervening between the plies, and heat
convertible layers on opposite sides of the membrane are
held together by extraneous means, e.g., by means of a frameO
The invention also includes an article which
comprises a multi-ply panel according to the invention as
hereinbefore defined together with a second panel (comprising
a single sheet or a plurality of sheets) held in spaced
relationship to said multi ply panelO Thus the invention can
be embodied in a hollow glazing unit.
As already stated, embodiments of the invention
in which the panel is in the form of a laminate are preferred.
The invention also includes a method of forming a laminated fire-
screening glazing panel comprising a first structural ply formed
by a vitreous sheet and at least one other structural ply formed
by a vitreous or plastic sheet comprising the steps of
a) applying onto one face of said first ply a layer
composed at least in part of material comprising a hydrated
metal salt which when sufficiently heated forms a solid porous
or cellular body forming a thermally insulating barrier,
b) applying another said layer to another structural
ply,
~ c) assembling said layered plies on opposite sides
,~ of a plastic membrane with said applied layers adjacent thereto,
G -13-
and ~04~91~
d) subjecting said assembly to heat and pressure
to bond said coated plies and said plastic membrane together
to form a laminate. This is a very simple and effective way
of forming a laminate-typ~ panel according to the teachings of
the present invention. The method obviates any need to apply
adhesive between the coatings on the structural plies and the
plastic membrane.
j Preferably, at least one of the heat convertible
10 ¦ layers is formed of an hydrated metal salt/ said hydrated
metal salt preferably being selected from the following groups
aluminates, plumbates, stannates, alums, borates, phosphates
; and alkali metal silicates. The advantages conferred by these
. ~. ..................................................... .
method steps correspond to the advantageous features of the
, ¦ panel formed according to the teachings of the present invention.
, ~ Advantageously, the hydrated metal salt layers
are applied as aqueous solutions which are dried before
assembly of the panel. For example, in order to obtain a
layer of hydrated aluminum phosphate, an aqueous solution
~ 20 containing 3.5 moles/litre of the salt is applied to a sheet,
; and subsequently dried by using a
:
.
~i -14-
10499~2
`
fan This solution may be o~tained hy mix~ng solution~
of phosphoric acid and aluminum chloride in stoichiometric
proportions. This is a very simple way of obtaining
the required layers of barrier forming m~terial.
Pre*erably a protective stratum i9 formed on
a face of the vitreous first structural ply before a
heat convertib]e layer is applied thereto, the pro-
tective stratum being composed of a material selected so
as to inhibit interaction between the barrier forming
material and the first structural ply. Preferably a
protective stratum is formed on each vitreous sheet
face of the panel onto which a layer of barrier forming
material is subsequently applied. Preferably at least
one such protective stratum is formed as a sheet of
; 15 substantially water impervious plastlc material, and
advantageously the plastic protective stratum i8 formed
of polyvin~l butyral. In preferred embodiments of the
method according to the teachings of the present invention
; at least one protective stratum is applied to a vitreous
sheet face as a coating. Preferably, such a protective
stratum is formed by depositing a coating of an anhydrous
metal compound onto a vltreous sheet face The advantages
of these preferred method steps according to the teachings
of the present invention are apparent from the correspond-
ing advantages of the panel formed according to the
teachings of the present invention.
,~:
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499~Z
Such a deposltion of an anhydrous metal compound
coating to serve as a protective stratum is preferably
performed by pyrolysis or hydrolysls, since these are
very convenient ways of forming a uniform coating which
is higilly resistant to the deleterious effects of a
barrier forming material.
Preferably, the barrier forming material is
selected ~rom the group consisting of alums, borateR, and
alkali metal silicates, and the anhydrous metal compound
; lO for forming a protective stratum is selected from the
group consistlng of zirconium oxide and anhydrouR
aluminum phosphate, however, the barrler ~orming material
may comprise hydrated aluminum phosphate, the anhydrous
metal compound for forming a protective stratum then
being selected ~rom the group consisting of titanium
oxide, zirconium oxide, tin oxide and anhydrous aluminum
phosphate,
Advantageously, a protective coating is ~ormed
to a thickness of between lO0 and lO00 Angstrom units.
Preferably, at least one heat-convertible layer is
formed to a thickness of between 0.1 mm and 8 mm,
and optimally, such a heat convertible layer is formed
, to a thickness of between 0.1 mm and 0.5 mm. In pre~erred
embodiments of the method according to the teachings of
the present invention, said coated plies are assem~led
~ and bonded to~ether on opposite sides of a said membrane
1 of plastic material comprising polyvinyl butyral
.~
-16-
. .
,.i - :
1049~12
In such a method according to the teachingR
of the present invention it i~ preferable for the layerq
applied to the structural plies to be layers of one or
more hydrated alkali metal silicates, since such barrier
forming materials are more readily able to withstand
the bonding temperature required tllan certain other
hydrated metal salts herein set forth.
; In some preferred embodiments of the method
according to the teachings of the present invention the
coated structural plies are assembled on opposite sides
of a layer of plastic membrane forming material comprising
an organic monomer with the applied heat convertible
layers next to said monomer containing stratumj and the
assembly is sub~ected to heat and pressure to polymerize
the monomer in situ and bond the coated structural plies
together on either side o~ the plastic membrane thus
formed. Embodiments having this feature have the advantage
that the polymeriz~tion temperature may be kept below
80C by suitable choice of organic monomer, and this
~0 obviates risk of premature conversion o~ the barrier form-
ing layer during the bonding process.
Urethane i8 a very suitable organic monomer
for incorporating in ~uch layer.
; When a plastic membrane is formed in this
manner it is very convenient to form the plastic pro-
tective stratum in a like manner.
The invention will now be described by way
of example with reference to the accompanying diagrammatic
~17-
.. . ~ . _ .
:
1049912
drawings in wl-ich figure~ 1 to 5 are cross~sec~ional
v~ews of various preferred embodiments of fire screening
glazing panels ~ccording to the teachings of the present
invention
EXAMPLE 1
~ fire screening panel was made as shown in
? figure 1. This panel comprises two sheets 1,1 of glass
e~ch of which~carries a layer 2 of hydrated sodium
silicate, ~nd these layers are bonded together on opposite
~; 10 sides of a membrane 3 of polyvinyl butyral.
The glass sheets 1 are of soda-lime glass 3mm
thick, the layers 2 of hydrated sodium silicate are
each 2.5mm thick, and the plastic membrane 3 has a thick-
' ness of 0.76mm.
'~ 15 In order to form the layers 2, hydrated sodium
~ilicate was applied in an aqueous solution having the
follo~ing properties:
Proportion by weight Si2
.
Viscosity 200 centipoises
Specific gravity 37 to 40 Baumé
., .
This solution was applied to a face of each
glass sheet while the sheets were substantiQlly horizontal
and at a temperature of 20C. ~le solution thus applied
was allowed to spread out over the glass sheets.
-18-
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1~4991Z
Current~ of warm air were then directed onto
the solution in order to dry it. Thls drying has the
effect of driving off excess, unbound water of solution
to leave a layer of hydrated sodium silicate on each glass
sheet. After ~ormation of these layers of hydrated
sodium sillcate on the sheets, the sheets were p~ ced
on either side of a sheet 3 of polyvinyl butyral 0.76 mm
thick as shown in figure 1,
In order to bond the panel together to form a
laminate, the assembled panel was placed in a chamber in
which reduced pressures could be obtained. Reduction in
pressure has the effect of removing any air which i8
; trapped between the various plies of the panel. After
reduction of pressure the temperature of the panel is
raised, also under partlal vacuum to 80C to reach a
pre-bonding stage of the panel After the "pre-bonding"
operation the bonding operation is performed in the
classical manner at a pressure of 15 kg./cm2 and at a
temperature of 130C. The panel thus formed may be
placed in a frame very easily and i6 very advantageous
in case of a fire. Indeed, $t has been found that such
a panel keeps its mechanical stability and its flame-
proof properties for 45 minutes, It should be noted that
on the advent of fire the layers 2 of hydrated sodium
silicate are converted to an anhydrous sodlum silicate
having an opaque porous form.
.,:;
-19-
f
,
~(~49912
~ en a fire screening panel according to
tne preserl~ examplc ls subjected to tlle ac~lon of fire
on one of its sheel~ faces, the layer of hydrated sodium
sllicate applied to the sheet close3t to the flre is
converted 'GO an opaque porous fire screening barrier
of an~iydrous sodium silicate. This anhydrous barrier is
somewhat thicker than the hydrated layer from which it
was formed, and is a very effective ~arrler against infra-
red radiation. During the course of the conversion, the
1~ bound water is driven off and thus contributes to a
limitation of the temperature increase in that layer.
During this phase-the plastic membrane helps to make
the temperature uniform across the whole area of the panel,
and any local llhot spots" in the firstly converted layer
are reflected in larger hot zones in the second layer.
When this first layer is completely dehydrated the other
layer of hydrated sodium silicate is in turn converted
to form an opaque porous barrier of anhydrous sodium
silicate.
~0 These phenomena enable t~e face of the fire
screening panel which is not directly subJected to the
action of fire to be m~intained at an acceptable temperature
for an increased period of time In fact it has been
found that when the fire screening panel i5 arranged
in a furnace wall the following results are achieved:
:~ .
-20-
~ ~049912 Temper~ture on outer
Temperature face of fire ~creening
Time within furnace panel
0 20C 20C
15 minutes 725C 100C
.~ 30 minutes 825C lOO~C
9~0C 200C
The panel has a high degree of mechanical
stabllity during and after conversion of its barrier
forming layers
:;~ In a variation of the embodiment shown ln
figure 1, use was made of glass sheets 1,1 which had
been sub~ected to a chemical tempering treatment involv-
lng a di~usion of ions into the glass from a contacting
medium. This chemical tempering is an exchange of sodium
: ions from surface layers of the treated sheets by
Potassium ions from the contacting medium which comprises
a bath of molten Potas~ium nitrate maintained ak a
temperature of 47~C. The result obtained from the point
of view of thermal insulation, mechanical stabllity and
~; e~fectiveness as a ~lame- and fume-proof barrier were
. 20 analogous to those obtained with the fire screening
panel described above. However, this modification has
~: a greater resistance to thermal shock during the first
few minutes of a fire than does the panel described above.
In a second modification for use in situations
~: 25 where there is only a very slight fire risk on one side
of the partition, the sheet of glass 1 to be directed
-21-
.
,. . .
~ .
10~99~2
towards ~hat slde is replaced by a sheet of plastic
material. Again, the results obtained ~rom the point of
view of resistance to fire were similar to those given
above,
In a third modification, a fire screening
panel was constructed exactly as described at the
beginning of this example, except that the layers 2 of
hydrated sodium silicate were formed to a thickness of
0,2 mm instead of 2.5 mm. From the point of view of
fire resistance, this modification is slightly less
effective than the panels described above However,
this panel does have the advantage of increased trans-
parency.
, In yet another modification, a fire screening
s 15 panel was constructed as described above, except that
the polyvinyl butyral membrane was replaced by a membrane
of polyvinyl chloride. Changing the membrane in this
way had no effect on the fire resistance of the panel.
EXAMPLE 2
The embodiment s'nown in figure 2 is similar
to that shown in and described with reference to figure
1, except that it incorporates an additional layer of
barrier forming material 2 and an additional plastic
membrane 3. The central layer of barrier forming material
2 was formed as a layer on one of the membranes 3, and
.
-22
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; 104991Z
the panel was assembled by a method similar to that
described ~lith reference to figure 1.
In tilis embodiment the glaS3 sheets 1 were
of soda-lime glass 3mm thick~ The layers 2 of hydrated
sodium sillcate were each 2.5mm thick and each
plastic membrane 3 had a thickness of o.76 mm.
This embodiment of fire screening glazing
panel can also easily be placed in a frame. It ulll
be appreciated that from the point of view of fire
resistance, this panel is better than that of Example 1
because of the additional thickness o~ barrier forming
material.
EXAMPLE 3
; To form the panel shown in Figure 3, two
sheets of glass 1,1 were each coated on one ~ide with a
protective stratum 4 o~ zirconium oxide 500 Angstrom units
thick, The zirconium oxide coating was formed ln known
manner by pyrolysis of a solution in alcohol which had
been sprayed through an atomizing nozzle onto a sheet of
, 20
- glass heated to 550C. The solution used comprised
denatured ethyl alcohol containing 150 gr/litre of
zirconium tetrachloride to which was added 10% by volume
o~ acetylacetone, The solution was used unheated.
,- The coated side of each sheet 1 was then
~- 25 covered with a heat convertible layer 2 of hydrated
,. . . .
-23-
'.~
~,
i ~ . .
1049912
sodium silicate. In an actual example~ protectively
coated glass sheets 1, each 4 mm thick, were covered
wlth heat convertible layers 2.5 mm thick by applying
a solution of ~Iydrated sodium silicate to the coated
sides of tlle sheets and then ventilating the sodium silicate
with warm air by means of a fan to drive off unbound
. water.
The sodium silicate solution applied had
the following properties: ;
! 10 Proportion by Weight SiO2 = 3.4
Na20
' Viscosity 200 centipoises
r/ Specific gravity 37 to 40 Baumé
The sodium silicate solution was applied and
then dried ~or 8 period o~ 12 hours at 30C in an
atmospherc having a relative humidity of 35~, m e
. coated sheets were then assembled on opposite sides of
a layer of Q urethane membrane 3 and the plies bonded
together to form a laminate. m e bonding temperature
. was kept below 100C in order to obviate risk of con-
verting hydrated sodium silicate to anhydrous sodium :
silicate,
The degree o~ fire resistance given by this
panel was similar to the results shown in Example 1.
In addition, the panel describe~ in the
present Example has the further advantage of maintaining
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10499~Z
it6 optical properties until the advent of fire, even
for a pr~l~nged period In particular, i~ has been
found that a panel incorporating such protective coat-
ings does not lose its transparency after prolonged
periods I-t has been observed that a reduction in
tr&nsparency will ta~e place in tl,e absence o~ protective
strata because of ~he interaction between hydrate~ sod~um
silicate and the glass sheets.
As a modification of the embodiment shown in
Figure 3, use ~as made of glass sheets 1 which had
previousl~ been sub~ected to a c'nemical tempering
treatment involving the exchange of sodium ions from
the glass ~ith potassium ions ~rom a contacting medium.
The use of tempered glass shee~s gave the panel an
increased resistance to breakage due to thermal shock.
In another modification, the sheets of glass
1,1 ~ere replaced by sheets of vitro-crystalline material,
and this also gave good results.
EXAMPIE 4
~ne embodiment sho~m in Figure 4 is similar
to that described in Example 3, except that it incorporates
an additlonal layer of barrier forming m~terial 2, and
an additional plastics membrane 3. The central layer o~
barrier ~orming material 2 was formed as a layer on one
f the plastic membranes 3, and the panel was assembled
by a method similar to that described in Example 3.
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Tlle thicknesses of the varlous plies of the
panel were the same as those in Xxample 3.
It will be appreciated that because o~ the
additional heat convertible layer 2, this panel gave a
greater degree o~ ~ire-resistance than the panel described
i in EXample 3.
In another em~odiment, the zirconium oxide
protective coatings 4 of Figure 4 were replaced by
'~,A coatings of indium oxide each 400 Angstrom units thick,
These coatings were formed in a known manner, by spraying ;
a solution o~ ind~um chloride through an auto~zing
nozzle onto hot sheets of glass where the indium chloride
was converted to indium oxide by pyrolysis. This
., .
modification also had very good fire resisting properties.
EXAMPLE 5
'~ In Figure 1, two sheets of glass 1,1 were
each coated on one side with a layer 2 of hydrated sodium
aluminum sulphate. In an actual example, glass sheets
5 ' each ~ mm thick weie each coated with a layer 2.5 mm ;
;~ 20 thick by applying wet hydrated sodium aluminum sulphate
to the sheets and then ventilating the coatings with warm
air by means of a ~an to drive off unbound water. The
~/l coated glass sheets were then assembled on opposite
sides of a stratum of urethane and the assembly was
~s 25 subjected to pressure and heat to polymerize the urethane
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, ~ .. .. .. . . .. . . . .... . . . . .
s :: : .,.
1049912
to form a polyurethane membrane 3 and bond the coated
glass sheets together to form a laminate. The bonding
temperature was kept below 80~C in order not to convert
the hydrated sodium aluminum sulphate to an anhydrous
, 5 material. ~nen the fire resistance of this panel was
tested, the results achieved were similar to those set
out in Example 1
In a variatlon of tllis em~odiment, use was
made of glass sheets 1 which had been subJec~ed to a
chemical tempering treatment involvin~ the diffusion of
s~ potassium ions into the glass from a contacting medium
in exchange for sodium ions from the glass.
In another embodiment for use in situations
where there is only a very slight fire risk on one side
of a partition, the sheet of glass 1 to be directed
towards that side was replaced by a sheet of plastic
material
In a third embodiment, the t~lo glass sheets
1,1 were replaced by sheets of opaque vitrocrystalline
material.
Similar results were achieved by these varian~
panels.
EXAMPLE 5
A panel was constructed as shown in ~igure 2
in a manner similar to that described in Example 5,
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10499~2
"
except that it incorporated an addltion~l layer 2 Or
hydrated sodium alumlrlum sulphate and an additional
plas~ic me~.brane 3. The central layer o~ barrier ~orming
material 2 was formed as a layer on one of ~he urethane
str~ta after that stratum had been formed on a layer 2 of
barrier ~orming material deposited on a structural ply 1,
but before polymerization there~f, and the panel ~las
assembled by a method similar to that described ln
Example 5, The two glass sheets were each 4 mm thick,
and the three heat convertible layers each had a thickness;
of 2.5 mm. This panel had a greater fire resistance
. than the panel of Example 5.
EXAMPLE 7
A ~ire-screening panel as schematically shown
in Figure 3 was made comprising two glass shee~s 1,1,
two heat convertible layers 2 of hydrated sodium aluminate,
. a membrane 3 of polyvinyl butyral, and two protective
. strat~ 4 o~ acrylic resin
The sheets 1 were each of soda-lime glass 4 mm
in thickness. They were each placed substantially
horizontally, and a pre-polymerized liquid was applied
to a depth of 100 microns on their upper surfaces, The
pre-polymerized liquid was formed by co-polymerization
; o~ acrylic acid and methyl acrylate and contained 5~
.~. 25 by weight Or methacryloxypropyltrimethoxysilane in order
'. '
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.;, .
to give increased adhesion to the glass, The treated
sheets wer~ then heated to 60C to obtain protective
strata of acrylic re~in by polymerization.
A layer 1 mm in thickness o~ hydrated sodium
aluminate wa~ then deposited onto the protected face of
;~ each sheet of glass. The hydrated sodium aluminate
whiell had been applied in solution was then dried in a
current of warm air. When the layers were dry, they
were assembled on either side o~ a membrane 3 of poly-
vinyl butyral o.76 mm thlck, and the a~sembly was
bonded together to form a laminate by the method described
;, in Example 1, except that care was taken to ensure that
the bondlng temperature did not rise above 120C in
order to avoid risk of converting the sodium aluminate
to an anhydrous material
Substantially identical panels have also been
made by a modified method. As above, each glass sheet
was given a 10~ micron coating of the same pre-polymerized
liquid, but instead of heating the sheets at this stage,
a 1 mm layer o~ hydrated sodium aluminate was applied to
one o~ the sheets and dried, A plast~c membrane 0.76 mm
thick was laid over this dried layer, and a second layer
o~ hydrated sodium aluminate was laid on the membrane
j to a th~ckness of 1 mm and then dried with warm air.
. 25 This second layer was then assembled to the coated ~ace
~,,`'
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10499~2
:
of the other glass sheet and the assembly was bonded
together by the method of Example 1, the bondin~
temperature again not being allowed to exceed 120C.
At thls temperature and pressure, the prepolymerized
liquid polymerizes to form acrylie resin protective
strata bonding the heat convertible layers to the glass
sheets, and the heat convertible layers are themselves
bonded together firmly via the intervenlng membrane of
polyvinyl butyral.
! 1~ In another embodiment, the acrylic resin
protective strata 4 were replaced by protective strata
of polyvinyl butyral, each o.76 mm thick.
In further modifications, the layers of
hydrated sodium aluminate were replaced respectively by
potassium aluminate, sodium plumbate, potassium plumbate,
sodlum stannate and potassium stannate, all in hydrated
form.
In yet f~rther modifications, each heat
convertible layer was composed of a different barrier
forming materia].
The glazing panels described in this Example
have and maintain good optical properties, and have
fire resistance characteristics similar to the panels
described in Example 3
.i'
EXAMPLE ~
.,
x A ~ire screening panel was made comprising t~o
~ sheets 1,1 (see Figure 3) of transparent vitrocrystalline
., .
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10~991~
material Or known cornposition, t~10 heat convertlble
layers 2 Or hydrated potassium aluminum sulphate each
0 5 mm thick, a membrane 3 o~ polyvinyl butyral ~.76 mm
in thickness, and two protective coatin~s 1~ of anhydrous
aluminum pllosphate each 5~ Angstrom unlts thick. The
vitrocrystalline sheets were each 4 mm thick
The anhydr~us aluminum phosphate protective
strata were formed as follows A solution in alcohol
of one mole of anllydrous aluminum chloride an~ one mole
of anhydrous phosphoric acid was placed in a bath and
, each sheet was dipped therein The sheets were arranged
vertically and withdrawn from the bath at a speed of 75
cm/minute in that position. One side of each sheet was
then wiped, and the sheets were placed in a furnace and
heated to 403C. Under these conditions, the alcohol
evaporates to leave a coating of anhydrous aluminum
phosphate on the unwiped side of each sheet.
A solution of potassium aluminum sulphate is
then applied to the sheets 1 on top o~ the protective
strata 4 to form heat convertible layers 2. This solution
is made by dissolving the potassium aluminum sulphate in
; distilled water and then heating the solution to evaporate
i some of the water and obtain a viscous liquid which can
easily be spread on the vitrocrystalline sheets. The heat
convertible layers are dried in warm air currents and
are assembled face to face via an intervening membrane 3
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~049912
o~ polyvinyl butyral 0.76 mm thick, and the assembly is
bonded together,
It has been found th~t the optical properties
o~ this panel are maintained during the course of time
~ince the said protective strata serve substantially
to prevent interaction between the vitrocrystalline
material and the pota8sium aluminum sulphate, The fire
resistance properties of this panel are similar to those
of the panels of Example 7,
EX~LE ~
A fire screening glazing panel as shown in
figure 3 was formed from two sheets 1,1 of transparent
vitrocrystalline material each 4 mm in thickness, two
heat convertible layers 2 of hydrated sodium borate each
1 mm in thickness, a membrane 3 of polyvinyl butyral 0,7~ -
mm thick and a protective coating 4 on the face of each
sheet 1 which carrled the heat convertible layer,
The heat convertlble layers 4 were of æirconium
oxide and were each deposited to a thickness of 350
Angstrom units by the technique given above in example 3,
The sodium borate layers 2 were deposited on the zirconium
oxlde coatings 4 on the sheets 1 using a saturated
solution of sodium borate. The layers thus obtained
were dried in currents o~ warm air so as to drive off
excess water,
, -32
104~91Z
~ nother embodiment a ~ire screening
glazing panel was made whlch was similar to that
described immediately above except that the sodium
borate layers 2 were replaced by layers of hydrated
sodium silicate each 2,5 mm thick, The h~drated sodium
silicate layers were applied by the technique described
in example 1.
It was found that the optical properties of these
panels were maintained during the course of time since
the zirconium oxide protective strata served substant~ally
to prevent interaction between the vitrocrystalllne
material and the hydrated sodium borate or hydrated
sodium silicate, The fire resistance properties of
these panels were good,
EXAMPLE 10
A ~ire resistant glazing panel, as shown in
figure 3 was made comprising two sheets 1 of soda-lime
; glass, two heat convertible layers of hydrated aluminum
phosphate each 1.5 mm in thickness, a membrane 3 of
polyvinyl butyral ~,76 mm thick and two protective
strata 4 of titanium oxide which were each 400 Angstrom
units thick, The glass sheets were each 4 mm thick.
The titanium oxide protective strata were
deposited by the well known vacuum evaporation technique,
` 25
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104991Z
The heat convertible layers of hydrated aluminum
phosphate were formed as follows: a 3,5 molar aqueous
solution of aluminum phosphate obtained as the reaction
product of solutions of hydrated aluminum chlorlde and
phosphoric acid was applied onto the sur~ace~ of ~he
glass sheets 1 bearing titanium oxide coatings. The
;i hydrated aluminum phosphate layers were then dried in
currents of warm air, A~ter drying, the panel was
; assembled according to the method described in example 1.
~, 10 rne optical properties of this panel were
maintained during the course of time and the fire
resistance properties were good,
As another variation, a similar fire screen-
ing vitreous panel was made in which the tltanium oxide
i 15 coatings were replaced by tin oxide coatings each 500
Angstrom units thick, These co&tings were applied in
the classical manner using a solution of tin chloride
and the well known hydrolysis process. ~e optical and
fire resistance properties of this modification were
similar to those of the panel first described in this
example,
r
EXAMPLE 11
.: A fire screening glazing panel, as shown in
figure 1 was m~de comprising two sheets 1,1 o~ soda-lime
i 25 glass each 4 mm thick3 two heat convertible layers 2
.,
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.',, ~ ,
104ggl2
of hydrated sodium phosphate each 5 ~m thick, and a
membrane 3 of polyvinyl butyral which was 0.76 mm in
thickness.
The layers 2 o~ hydrated sodium phosphate were
obtained by apply~n~ an aqueous solution o~ sodium
phosphate on to the glass sheets, and the sheets ~rere
then heated to 10~C in order to drive of~ the free
water ~lithout~ o~ course, converting the hydrated sodium
phosphate to anhydrous material.
After cooling, the sheets were assembled and ;
their respective heat convertible layers were bonded
together on either side of a membrane o~ polyvinyl
butyral, using a method similar to that described in
example 1, except that the rnaximum bonding temperature was
maintained below 103C.
This panel had extremQly good fire resLstance
properties.
A6 a variation, a similar panel was made in
which the heat convertible layers o~ hydrated sodium
phosphate were replaced by layers o~ hydrated potassium
; phosphate each 2 mm thick This panel also had good
fire resistance properties.
; EXAMPLE 12
Modified glazing panels were made correspond-
ing to those described in examples 3, 4 and 7 to 1~,
- except that in these modifications no protective strata
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104991Z
:
were presen'~ e results obteined from the point of
view of fire resistance were substan~ially ldentical to
similar panels which did include protective strata as
described.
-~ 5 The cost of manufscture of these modified
panels i8 somewhat less than thst of otherwise similar
panels incorporating protective strata, but it will be
appreciated that these modified panel6 tend to undergo
a deterioration in their optical properties and, in
particular, in their transparencies during the course
of time as a result of interaction between the barrier
forming material and the vitreous sheets of the panels
This interaction is greatly inhibited and, in some cases,
~; substantially ellminated by the presence of the protective
` 15 strata.
The use o~ heat convertible layers o~ aluminum
ph?sphate is particularly advantageous in the absence
of a protective strata, since, when converted by heat,
- this material bonds itself very s~rongly to a vitreous
`~ 20 sheet to which it is applied This enables the panel
to maintain its efficiency, even if a vitreous sheet of
the panel should be broken (as by therrnal shock) since
the broken fragments can be retained in position by their
adherence to the converted layer.
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~0499~
EXA~IPIE 13
~n opaque fire screening glazlng panel, such
as is schematically shown ~1 Figure 5, was made compris-
ing a panel identical in all respects with the glazing
' 5 panel described in example 1 which was bonded to a ~ mm
thick ~heet 5 o~ polyurethane via an intervening layer 6
of polyvinyl butyral o,76 mm in thickness, The fire
resistance properties of this composite panel were
generally similar to those set forth in e~ample 1,
Although the invention has been herein
. shown and described in what is conceived to be the most
practical and pref-erred embodiments, it is recognized
! that departures may be made therefrom within the scope
of the invention which is not to be limited to details
disclosed but is to be accorded the full scope of the
claims so as to embrace any and all equivalent structures
- ond methods,
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