Note: Descriptions are shown in the official language in which they were submitted.
o
The present invention relates to a window assembly
and to a process for producing the assembly. More
particularly, the invention contemplates a window assembly
including a sheet of optically transparent material, such as
glass, and a gasket of a polymeric material which is
polymeri2ed and cured in situ to encapsulate the marginal
peripheral edge portion of the sheet. The gasket is typically
formed by a reaction injection molding process. The assembly
can be shaped to constitute a vehicle windshield, for example,
in which case it can be inserted readily to close a windshield
opening surrounded by a frame of appropriate shape to
cooperate with the gasket of the assembly.
Initially, windshield assemblies for vehicles were
comprised of a plurality of elements including adhesive
sealants applied around the marginal edges of the glass sheet,
suitable mechanical fasteners such as metal clips, and
exterior decorative trim strips disposed to cover the junction
between the marginal edges of the glass sheet and the adjacent
portion of the vehicle frame.
Clearly, such structures were costly in both
material and labor.
Subsequently, in an endeavor to improve the
structure, unitary window assemblies of the type illustrated
in U.S. Patent 4,072,340 were developed. These assemblies
include a sheet of glass, an adjacent frame, and a casing or
gasket of molded material, such as polyvinyl chloride,
extending between the frame and the peripheral edge of the
window to hold the sheet of glass and the frame together.
Fasteners are provided at spaced locations along the frame
such that the entire assembly can be guided into location over
the opening in a vehicle body as a unit
~2~5!3 C~9~3
with the fasteners extending through aligned apertures in the
vehicle body and secured from the interior of the vehicle.
Other window assemblies, such as illustrated in U.S.
Patent 4,139,234, include a rnolded casing or gasket around the
edge of the pane of glass with fasteners molded in and
projecting from the casing or gasket for purposes of
attachment to an associated vehicle body.
The relatively heavy frame members of the above
assemblies, typically cast from zinc or other metals or alloys
and/or the molded gasket or casing for securing the frame to
the window provides significant weight in each window
assembly. Also, as illustrated in ~.S. Patent 4,072,340, the
exterior decorative frame, which requires fastening means
along the length thereof to secure the entire assembly in a
vehicle, requires expensive casing or gasket techniques
rendering the frame members expensive and time-consuming to
install.
In an endeavor to reduce the overall weight of a
window assembly of the type discussed above and to reduce the
costs thereof, other window assemblies have been developed of
the general types illustrated in U.S. Patents Nos. 3,759,004
and 4,364,595. The structure of the former patent includes a
glass sheet, with a trim strip surrounding the edge thereof,
secured within a suitably framed opening in a vehicle by means
of an adhesive pressed between the glass and/or the trim strip
and the adjacent portion of the frame around the opening of
the vehicle. The trim strip is formed of flexible plastic
material with a channel portion which embraces the edge of the
glass sheet and a front decorative strip portion which extends
from and can hinge relative to the edge of the front wall of
the channel portion which lies on the inside of the trim strip
when it is fitted around the glass sheet. The trim strip may
l~ss~o
be maintained in position on the glass sheet by suitable
retaining clips of spring metal, Eor example.
The latter oE the above mentioned patents
illustrates another window assembly which is installed to
close a vehicle opening, for example, as a unit preferably
from the outside. The assembly includes a sheet of glass, one
of sever~l types of decorative frame or trim members
surrounding the glass sheet, and one or more attaching members
secured directly to the glass sheet but concealed from view.
Preferably, the attaching means are metallic studs rigidly and
securely bonded directly to the glass surface with suitable
adhesive. The decorative frame member can be injection
molded, the patent discloses, around the sheet of glass.
The present invention is a window assembly of com-
paratively low weight and cost, which can be assembled and
installed in a vehicle with minimal handling costs.
The present invention relates to a window assembly
or glazing and to a method of making the same wherein the
window material, typically a glass sheet, carries a
surrounding synthetic resin mounting member or gasket which
encapsulates the marginal periphery of the glass sheet. The
mounting member or gasket is applied to the periphery of the
glass sheet by injecting into a mold cavity which surrounds
the periphery of the glass sheet a composition which is
capable of polymerizing and curing therein to produce the
gasket; the composition assumes through the autogenous
mechanism incident to its polymerization and cure, within the
closed mold cavity, intimate contact with the walls which form
the mold cavity and with the glass sheet. Excellent results
have been achieved by forming the mounting member of a
polyurethane composition which cures to a microcellular
elastomer.
~25S~9~
The process of the instant invention subjects the
glass or other transparent sheet material only to low
pressures, differing in that respect from processes by which
window assemblies having molded plastic frames have heretofore
been made, for example by injection molding where a
thermoplastic material such as polyvinyl chloride or the like
is injected into contact with the surface of the window
material at extremely high pressures, typically ranging from
5,000 to 20,000 psi. In many instances, the desired preformed
window assemblies include glass sheets having relatively small
irregularities formed therein during the manufacturing
process. These irregularities are typically caused by the
surface of the glass being comprised of zones wherein the
normally flat planar configuration is interrupted by a series
of small ripples defined by an array of adjacent rapid changes
in the surface dimensions. In instances where such glass is
used in the injection molding process considerable breakage
can be expected. Thus, the high injection pressures required
in the injection molding processes require a substantially
high pressure (clamp tonnage) to hold the mold surface against
the glass surface. Since the steel surfaces of the molds do
not conform to the irregularities ~and cannot be designed to
do so due to the non-repeatable nature of the irregularities),
these high pressures oEten fracture the glass particularly in
the zones containing the irregularities.
The preferred resins for use according to the
invention are polyurethanes, preferably comprising the linear
or slightly branched polypropylene glycol polyethers and
diphenyl methane diisocyanates (MDI) which are slightly
modified either by carbodimide or by reaction with glycols to
provide isocyanate compounds which are liquid at room
temperature and low enough in viscosity to satisfy the
1;~5~0~
processing requirements of high pressure metering and
mixing equipment.
The resins are formulated to be polymerized when
injected into the mold cavity, where the polymerization and
curing occur. The reactivity is controlled to provide
sufficient polymerization and cell stabilization, a
relatively short mold residence time being sufficient for
the assembly being produced. In this respect, while room
temperature cure is possible the mold surfaces typically
10 are maintained at 140 to 160 F. temperatures which
laminated glass products can withstand.
It is an object of the present invention to
p}oduce a preformed window assembly including a glass or
other transparent sheet and an encapsulating molding of a
type of synthetic polymer, such as polyurethane, which
polymerizes to adhere in ti&ht sealing relation with the
adjacent glass surface enabling the entire preformed
assembly to be installed to close a vehicle or other
opening with minimal manipulation.
According to the present invention, there is
provided a window assembly for mounting in an associated
framing member, comprising: a sheet of transparent
material; a reaction injected molded gasket composed of a
3 synthetic polymer adhered to predetermined portions of the
sheet; the gasket having been polymerized and cured in situ
adjacent the predetermined portions of the sheet and having
assumed through the autogenous mechanism incident to its
LCM/mls
-- 6 --
polymerization and cure while confined, intimate contact
with ~he portions to which it is adhered; and the gasket
providing for the window assembly both an exposed polymeric
mounting surface for subse~uent contact with the framing
member and an outer exposed polymeric trim section adjacent
one surface of the sheet.
Also, according to this invention, there is
provided a method for producing a window assembly of a
transparent sheet material and a gasket adhered to
predetermined portions of the sheet, the gasket having an
exposed mounting surface for subsequent attachment to an
associated framing member and an outer exposed trim section
adjacent one surface of the sheet, the method including the
steps of: positioning a transparent sheet material within
the interior of a mold chamber formed by a plurality of
cooperating mold sections, the mold sections including a
gasket shaping surface which cooperates with a
predetermined marginal edge portion of the sheet for
defining a gasket forming cavity having a shape
corresponding to the desired shape of the gasket; injecting
into the gasket forming cavity a composition which is
capable of polymerization and cure to produce a gasket and,
when cured in contact therewith, adheres to the marginal
surfaces of the sheet material; controlling the pressure at
which the composition is injected into the gasket forming
cavity to one sufficiently low that the sheet material is
not damaged; controlling the temperature of ~he gasket
LCM/mls
,:
:
-`6a -
9~2590~0
forming cavity, the injection of the composition and the
amount of the composition injected 90 that the composition
polymerizes after its injection and assumes by the
autogenous pressure incident to polymerization intimate
contact with the gasket forming cavity and with the sheet
material, and cures while in such contact; and remaving the
assembly from the mold chamber.
In the accompanying drawings:
LCM/mls
1%~90
Fig. I is a rear elevational view of a preformed
window assembly according to the invention;
Fig. 2 is an enlarged fragmentary sectional view of
the assembly of Fig. 1 taken along the line 2~-2 thereof;
Fig. 3 is an enlarged fragmentary sectional view oE
the peripheral edge section of the window assembly of Figs. 1
and 2 showing the application of a bead of adhesive prior to
installation oE the assembly;
Fig. 4 is a fragmentary vertical sectional view of
the window assembly of Figs. 1, 2 and 3, after it has been
installed to close an opening;
Fig. 5 is a schematic view showing the preferred
process for producing the preformed window assembly of Figs. 1
through 4;
Fig. 6 is a more detailed schematic view showing the
basic components which are involved in practicing the process
of Fig. 5;
Fig. 7 is a top plan view of a typical mold designed
to produce the preformed window assembly of Figs~ 1 through 4;
Fig. 8 is an enlarged fragmentary sectional view of
the mold structure of Fig. 7 taken along the line 8--8
thereof;
Fig. 9 is an enlarged fragmentary sectional view of
the vacuum head portion of the mold assembly of Figs. 7 and 8
taken along the line 9--9 of Fig. 7; and
Fig. 10 is an enlarged fragmentary sectional view
showing cooperating pad members for supporting a glass article
during the production of a window according to the invention
by the process of Fig. 5; mold cavities in lower and upper die
sections are also shown.
Referring in more detail to the drawings, Figs. 1,
o
2, 3 and 4 show a preformed window assembly according to the
present invention and produced by the method thereof. More
specifically, a preformed backlight 10 for insertion into a
suitable opening in a vehicle body is shown. The vehicle body
has a back wall portion 12 which generally defines the opening
to be closed. The back wall portion 12 is typically formed of
a sheet m~tal stamping and is suitably secured to a
strengthening member 14, for example by electric resistance
welding. Extending outwardly of the back wall portion 12 and
typically integral therewith is a coextensive wall portion 16
which together with the back wall portion 12 defines a cavity
which is adapted to receive the preformed window assembly lO.
The wall portion 16 terminates in a rather abrupt bend at
which point the material 18 is contoured and integral with the
sheet metal defining the silhouette of the associated vehicle.
The preformed backlight assembly 10 includes an
appropriately shaped window material 20, typically formed of a
sheet of optically transparent glass. A synthetic resin
mounting member or gasket 22 encapsulates the front, rear, and
peripheral edge portions of the window material 20. The outer
bead or trim portion 24 of the gasket 22, as best seen in Fig.
4, covers a gap between the peripheral edge of the window
material and the metal of the vehicle body which surrounds the
opening, as exemplified by the wall portion 16 when the
preformed assembly 10 is actually installed on the vehicle.
The portion of the mounting member or gasket 22
which extends inwardly of the trim portion 24 surrounds the
peripheral edge and the rear edge of the window sheet material
20 and terminates along the rear surface thereof. There is
also a rib or dam member 26 on the rear surface of the window
material 20 and spaced inwardly of the termination of the
mounting member or gasket 22. The zone between the
'~-
39~ `
termination of the gasket 22 and the rib 26 is adapted to
confine a bead of suitable adhesive material used in mounting
the preformed window assembly. Further, there are tabs 28
integral with the gasket 22 and the rib 26 and bridge member
30 between the gasket 22 and the rib 26 and tabs 28. The tabs
28 are locating and indexing means useful during the mounting
of the assembly onto an associated vehicle and to retain the
assembly in place until the associated adhesive material cures
to effect the desired bond between the preformed assembly and
the mating portion of the vehicle.
The first step in producing the backlight 10
involves thorough cleaning of the front, rear and peripheral
edges of the glass sheet material 20 to prepare the surfaces
for adherence to the mounting gasket 22, the rib 26 and the
associated tabs 28. It has been found to be desirable in
certain instances to include a layer 32 of opaque paint, glass
frit enamel or the like applied to a portion of the rear
surface of the sheet 20. The opaque material of the layer 32
is typically employed in instances where it is necessary to
conceal, from the exterior, window mounting materials and
structures, as well as, for example, windshield wiper drive
mechanisms, and in some instances where it is helpful to
protect same from ultraviolet radiation.
The next step in producing the backlight 10 is
applying a primer coating to the previously cleaned glass
surfaces. Satisfactory results have been achieved by
initially employing a layer 34 of a product which is
commercially available under the designation "8etaseal, Glass
Primer 435.18 Commercial Grade," from Essex Chemical
Corporation, Clifton, ~ew Jersey, U.S.~. The glass bond area
is initially wiped with the primer to form the layer 34, which
acts as a coupling agent. The primer material is a clear
_ g~
~2S~
moisture-sensitive primer comprising
gama-aminopropyltriethoxysilane, which promotes adhesion
between other Betaseal products and glass.
Following the application of the layer 34, a second
primer layer 36 is applied over the layer 34. Satis~actory
results were obtained by utilizing a product which is
commercially available under the designation "Betaseal, Glass
Primer 435.20 Commercial Grade," from Essex Chemical
Corporation. This material is a blackout primer which
prevents ultraviolet degradation oE urethane sealants and
adhesives and assists in the rapid formation of a
hydrolytically stable bond between the glass and the urethane.
Approximately 20 minutes after the superposed layers 34 and 36
have been applied, the assembly is placed in the die cavity of
a mold, where the polyurethane gasket 22, the rib 26, and the
tabs 28 are produced; the mold is a part of apparatus
subsequently described in detail with reference to Figs. 5
through 10.
It is often desirable to apply a coating 38 to the
outer exposed surface of the trim section of the gasket 22
before the structure is installed in a vehicle. The coating
38 can be a black urethane based paint, such as one
manufactured by PP~ Industries, Inc., Pittsburgh,
Pennsylvania, U.S.A., under the designation Purethane 700
HSE-848. The paint coating 38 is then baked at approximately
140 - 150 F. for about 20-30 minutes. The coating 38 is
applied to protect exposed polyurethane gasket material from
degradation which would otherwise be caused by exposure to
ultraviolet radiation normally present in unfiltered sunlight.
The preformed window assembly can be installed in an
appropriate vehicle opening by applying a bead 40 of adhesive
material, for example a urethane sealant such as a sealant
_~_
12S~ O
manufactured by the Essex Chemical Corporation designated as
Betaseal 55l.2, with water paste, to the marginal rear edge
surface between the gasket member 22 and the spaced apart rib
26, positioning the assembly in alignment with the vehicle
opening, and pushing the assembly into position. When the
assembly is aligned with the vehicle opening, the tabs 28 are
aligned with spaced cooperating apertures 42 in the back wall
portion 12 and the associated strengthening member 14 of the
vehicle. The tabs 28 have tapering noses to facilitate
alignment. As the assembly is pushed int~o position, the
tapered nose portions of the tabs 28 travel through the
apertures 42 and are caused to snap into locked positions
where they maintain the adhesive bead 40 in a compressed
condition ~see Fig. 4). As soon as the adhesive material 40
cures, the installation is complete.
Referring now to Figs. 5 through 10, the apparatus
for producing the assembly 10 includes a primer station 50 and
a molding station 52 (see Fig. 5) which comprises a bulk
storage area 54 from which a stream which is a blend of
polyol, a chain extender, e.g., ethylene glycol, pigment, and
a catalyst and a separate stream of an isocyanate are
delivered as required to a urethane metering station 56. The
isocyanate from the bulk storage tank 54 is delivered to a
conditioning tank 58, while the polyol blend is delivered to a
tank 60. The outlets of the tanks 58 and 60 communicate with
respective displacement cylinders or high pressure metering
pumps 66 and 68 through respective recirculation pumps 62 and
64 to keep the material flowing at all times through the
supply lines leading to a mixing head 74 and through
recirculation lines back to the displacement cylinders 66 and
68. Heat exchangers 70 and 72 are employed in the system to
maintain the desired reactant temperatures. Constant motion
.
~s~
and temperature control are essential to keep the various
insoluble compounds in suspension at temperatures at which the
reactants remain inert and liquid, but at which they will
react rapidly when brought together.
An injection system is provided to inject a charge
composed of closely controlled portions of the two circulating
streams into the mold in a smooth even flow. Measured charges
of the two streams are delivered to mixing head 74 from the
outlets of the displacement cylinders 66 and 68 respectively,
by the action of pistons which are represented schematically.
The injection into the mixing head 74 is under an applied
pressure in the range of approximately 1000 to 3000 psi. The
two streams are mixed thoroughly in the mixing head 74. The
mixture is delivered therefrom to an associated mold 76 at a
pressure of approximately 50 to 100 psi. The mold is
typically maintained at a temperature within the range of 140
- 150 F.
The mold 76 is comprised of a lower section 78 (Fig.
7) and an upper section 80. Suitable means, not shown, are
provided to open and close the mold sections 78 and 80. When
the sections are open, the glass sheet 20 is positioned on the
lower section 78 so that portions of the rear surface of the
glass rest on appropriately positioned pads 82. After the
glass section 20 is suitably positioned on the pads 82 of the
lower mold section 78~ the upper section 80 is lowered into
position so that the outer peripheral edges of the cooperating
sections 78 and 80 can be clamped together in metaL-to-metal
contact outwardLy of the mold cavity. The upper die section
80 of the mold carries pads 84 which function in cooperation
with the pads 82 to press yieldingly against the glass sheet
20 and retain the same within the mold cavity. The cavity of
the mold 76 is larger than the formed glass sheet 20 to avoid
~L2~
any glass- to-metal contact.
There are vacuum heads shown in Figs. 7 and 9 in the
upper mold section 80 of the mold 76 to carry the glass
upwardly along with the die section 80 when the molding
operation has been completed and it i9 desired to remove the
glass sheet 20 from the mold 76. The vacuum head consists
primarily of a vacuum cup 86 which communicates with a source
of vacuum through a vacuum line 88.
A number of movable mold segments, indicated
generally at 90 are provided at spaced points around the
circumference of the mold corresponding to the positions of
the tabs 28. ~11 of the mold segments are identical and are
slidably received in respective recesses 92 provided in the
lower mold member 78. The outer end of each segment 90, in
respect to the mold, is affixed to a block 94 which is
operatively connected to the distal end of a reciprocal piston
rod 96 of a conventional fluid operating cylinder 98. The
opposite or inner end of each segment 90 terminates in a
contour corresponding to the outer profile of gasket 22 and
includes extension 100 which provides the undercut in tab 28.
In operation, the piston rod 96 is extended, moving the mold
segment 90 forwardly (Figs. 8 and 10) in readiness for
receiving the charge of gasket forming resin. Vpon polymer-
ization and cure of the gasket material, the piston rod 96
and movable mold segment 90 are retracted, as shown in phantom
in Fig. 10, withdrawing extension 100 from the undercut
portion of the tab 28, releasing the tab and freeing the
backlight assembly for removal from the lower mold member 78
by the vacuum pick-up of upper mold member 80.
After discharge of the assembly from the mold member
78 any excess gasket material or flash is removed at a station
100, the assembly washed and dried at station 110 and the
~25i9(~9~
paint coating 38 applied to the outer exposed trim section of
the gasket 22 and baked to cure at the station 120.
The following example constitutes the best mode
presently contemplated by the inventor. It is to be construed
as illustrative, and not as limiting.
EXAMPLE
The surfaces of the upper and lower mold sections 80
and 78 which surround the mold cavity between the two, when
assembled, were treated with a solvent-based mold release
agent which is a blend of waxes; the particular mold release
agent is commercially available from Park Chemical Company,
Detroit, Nichigan, U.S.A., under the trade designation
PRC-789. A glass sheet 20 was then appropriately positioned
on the lower mold 78, after which the upper mold 80 was mated
with the lower mold 78, and the two were clamped together. A
charge composed of one part by weight of a polyol composition
and 0.63 part by weight of an isocyanate was then forced into
the mixing head 74 under a pressure of 2,500 psi and from
thence into the mold 76 at a pressure of approximately 50 psi.
The polyol and isocyanate streams were at a temperature of
110 F., while the mold 76 was at a temperature of 145 F.
The polyol and isocyanate streams were thoroughly mixed in the
head 74, before they reached the mold 76. Approximately one
and one half minutes after the urethane composition was
injected therein, the mold 76 was opened, and the assembly 10
was removed therefrom.
The resulting elastomer gasket 22 was microcellular,
had a specific gravity of 1.07 g/cc, a hardness (Shore "A") of
90, a tensile strength of 1500 psi, a percent elongation at
break of 279 and a flexural modulus (at 75 F.) of
approximately 3500 psi.
The polyol composition used in carrying out the
_i~
procedure described in the foregoing example was composed of
100 pounds o f a base polyol, namely a 6000 molecular we;ght
polyether triol with ethylene oxide "capping," sold under the
trademark "Voranol" 5815 by the Dow Chemical Company, Midland,
Michigan, U.S.A.; 10 pounds of ethylene glycol; and 3 pounds
of 20% carbon black in polyol.
The isocyanate used in practicing the procedure of
the foregoing example was a modified 4,4' diphenyl methane
diisocyanate sold under the trademark Rubinate LF 179 by the
Rubicon Chemicals Inc., Geismar, Louisiana.
The above constituents were cataly7ed by the
addition of dibutyl tin dilaurate, and a solution of
triethylenediamine in dipropylene glycol.
It will be appreciated that various changes and
modifications can be made from the specific details of the
instant invention as described above without departing from
the spirit and scope thereof as defined in the appended
claims. For example, while the preformed window assembly 10
is a backlight structure for an automobile, it must be clearly
understood that an assembly according to the invention will
function equally well in any fixed glazing application for
vehicles such as automobiles, trucks, vans, or buses, as well
as in many other applications including architectural,
appliance, and boating environments.
The configurations of the trim portion 24 and of the
molding 22 lend themselves to the accomplishment of
aerodynamic objectives of the automotive industry. An ongoing
objective of automotive designers is to create more
aerodynamically clean vehicle configurations to increase the
vehicle efficiency and thereby reduce the power requirements
to enable lower fuel consumption. Since the vehicle backlight
and windshield are obvious sources of considerable resistance
~2~9C3~
to smooth air flow, constant attention has been focused on the
aerodynamic design improvement of the configuration of the
backlight and windshield assemblies and the attendant
fastening means and decorative trim.
It will be appreciated, in considering the
windshield structures oE the presently known types as
discussed earlier herein, that the various fastening means and
trim have been imperfect from an aerodynamic standpoint and
have created undesirable eddy currents adversely affecting the
overall efficiency of the vehicle, as well as causing onerous
wind noises in the interior of the vehicle during locomotion.
The present invention enables a preformed windshield assembly
which can be integrated into a flush mounting system wherein
the trim portion corresponding with a portion 24 of the
mounting member or gasket 22 is substantially flush with the
adjacent surfaces thereby very materially improving the
aerodynamic characteristics and reducing undesired eddy
currents and resultant wind noise.
While the preEerred embodiment of the invention
utilizes a composition of polyurethane to achieve the desired
results, other compositions of nylons, polyesters and epo~ies
may be suitably utilized.
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