Note: Descriptions are shown in the official language in which they were submitted.
36(:i 7
DESCRIPTIO~
TITLE :
"_Composit~_~an~ high resistance ~ ts "
The present invention relates to a pane or glazing
having a high resistance to impacts and in particular
to projectiles fired from fire-arms.
It is already known to form such a window pane by
means of a sheet of a polycarbonate interposed between
two sheets of glass which are adhered to the sheet of
polycarbonate and may be themselves part of a laminated
pane, for example a structure known by the trade mark
Triplex and formed by two`or more sheets of glass assem-
bled by a ~ilm of polyvinyl butyral.
Owing to the very high resistance to impacts of
polycarbonates, this window pane permits, for a given
weight, a substantial improvement in the resistance to
impacts over other bullet-proof panes or the like of known
type. However, it has been found that this resistance to
impacts oP the composite pane having a polycarbonate sheet
described hereinbefore is not as good as that which could
be theoretically expected from the ballistic efficiency of
polycarbonate. Further, the different coefficients of ex-
pansion of glass and polycarbonate results, in this known
composite pane, in problems of behaviour at extreme tempe-
ratures which have not been solved up to the present time.
me object of the invention is therefore to provide a ccmposi-
te window pane having a high resistance to i~pacts,of the type com-
prising at least one sheet of transparent plastics material which
~3i j,~,~
~3L4~7
resists impacts and is interposed between cwo sheets of glass or
the like, which avoids the aforementioned drawbacks of the known
composite window pane based on polycarbonate.
According to the invention, there is provided a window
pane of the aforementioned type which comprises a film of a trans-
parent liquid between each face of said sheet of plastics material
and the adjacent one of said sheets of glass, and flexible sealing
means comprising a frame which extends around the pane and com-
prises two annular outer flanges between which flanges said sheets
of glass are engaged, and two peripheral annular portions which
project inwardly of the frame and are respectively sealingly engaged
between marginal portions of the sheet of plastics material and
marginal portions of said sheets of glass and allow relative move-
ments between said sheet of plastics material and said sheets of
glass in said substantially parallel planes, said frame being
adhered to said sheets of glass.
According to a feature of the invention, the transparent
liquid is preferably glycol.
Further features and advantages of the invention will be
apparent from the ensuing description with reference to the
accompanying drawing which is given solely by way of example and
in which:
The single Figure is a cross-sectional view of a com-
posite window pane having a high resistance to impacts according
to the invention.
The pane 1 shown in the Figure comprises a relatively
thick sheet 2 of a transparent impact resisting plastics material,
for example a polycarbonate. The sheet 2 of plastics material is
~; - 2 -
17
interposed between two laminated panes of known type 3a and 3b.
The pane 3a is of Triplex type and comprises two sheets of glass
4 and 5 which are assembled by a film 6 of polyvinyl butyral. The
laminated sheet 3b is of Triplex type formed by two sheets of glass
7 and 8 which are assembled by a film 9 formed by a small number of
sheets of polyvinyl butyral, an additional sheet of glass
- 2a
. ,,, ~ ,
~L~4;36~7
10 being a~sembled with the sheet 8 oE the Triplex sheet
3b by a relatively thick layer 11 Eormed by a large
number of shee~s of polyvinyl but~ral.
AccordincJ to the invention, a film 12a, 12b of a
transparent fluid is interposed between each face of the
sheet 2 of plastics material a~d an adjacent sheet of ylass 5
and 7 respectively. This fluid may be a paste or liquid
such as glycol which has the advantage of having a very low
freezing point and consequently allowing the use of the pane
1 under extreme climatic conditions. The fluidtightness
with respect to the fluid between -the sheet 2 of plastics
material and the adiacent sheet of glass 5 and 7 is achieved
by means of a U~section frame 13 which constitutes an outer
sealing element and extends around the pane 1 and has flan-
ges 14a, 14b which are adhered to the outer faces of thelaminated panes 3a and 3b respectively. The rame 13 further
comprises a web 15 from which inwardly project two peripheral
annular portions 16a, 16b which constitute an inner sealing
element and are each disposed between a marginal portion of
20 the sheet 2 of plastics material and the facing marginal
portion of the adjacent sheet of glass 5, 7 respectively.
The annular portions 16a and 16b are secured to the corres-
ponding marginal portions of the sheets of glass 5 and 7
by adhesion and the thickness of these annular portions is
equal to,or less than,the films 12a and 12b of transparent
fluid. Preferably, the frame 13 and the projecting annular
portions 16a and 16b are in one piece and are produced
36~1~
from a plastlcs material which has a certain flexibility.
With this embodiment of the sealing element, the sheet of
plastics material 2 is not fixed directly to the adjacent
sheets of glass 5 and 7 and this eliminates the problems
relatecl to the diEferential expansion of the shee-t of plas-
tics material and the ad,acent sheets of.glass which occur
in the known pane described hereinbefore at the beginning
of the present description. On the contrary, the arrangement
of the sealing element according to the invention enables
this differential expansion to occur without this resulting
in a deformation of the sheet 2 of plastics material or
of one or more sheets of glass making up laminated panes 3a
and 3b,owing to the fact that the frame 13 is flexible and
accommodates these differences in expansion. Further,
although the annular portions 16a and l~b are not fixed to
the sheet 2 of plastics material, the seal is perfectly
achieved since, on one hand, these annular portions 16a, 16b
are adhered to the sheets of glass 5 and 7 and, on the other
hand, the flanges 14a, 14b of the frame 13 are adhered to
the cQnfrontin~ faces of the laminated panes 3a and 3b, so
that there can be no escape to the exterior of the transpa-
rent fluid of the fi1ms 12a and 12b.
Lastly, when the pane 1 is mounted in a fixed frame-
wor~ 17, a ~oint 18 of put-ty or mastic or the like is inter-
posed between this framework 17 and the frame 13.
Apart from the fact that it solves the problems ofbehaviour under extreme climatic conditions, the pane accord-
ing to the invention has the surprising advantage of having
,
.
~4;~ )7
a ballistic efficiency or resistance which is a distinct
improvemen-t over that of the aforementioned known pane.
Although the causes of this improvement are difficult to
determine, i-t might be thought -that the^ interpostion of a
film of fluid between the sheet of plastics material and the
adjacent sheets of glass has for effect to isolate completely
this sheet of plastics material and allow its ballistic pro-
perties to be fully taken advantage of, which is not the case
in the known pane in which the sheet of polycarbonate is
adhered to the adjacent sheets of glass.
Although a single embodi~ent of the invention has
been described, it must be understood that many modifications
may be made therein without departing from the scope of the
invention. Thus, for example, the described sealing element
may be replaced by a simple flexible peripheral sealing ele-
ment of putty or mastic or the like disposed in the place of
the annular portions 16a and 16b and respectively fixed to
the sheet of plastics material 2 and to the sheets of glass
5 and 7~ Further, the laminated panes 3a and 3b may have a
different structure and, in the extreme case, these panes
may be reduced in some applications to a single sheet of
glass. Note that the term "glassl' is here employed to desi-
gnate any material such as glass, mirror or the like which
is transparent and has a sufficiently hard surface so that it
cannot be easily scratched.
The pane according to the invention may be employed
-
~3~iC)7
in all applications where it is necessary to provide a
transparent and light panel which is very resistant to im-
pacts, for example for the cons-truc-tion of windscreens and
window panes of automobile vehicles, windows or doorsof
buildings etc...
