Note: Descriptions are shown in the official language in which they were submitted.
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TRANSPARENCY WITH COATING HAVING PRI1~R'FOR EDGE SEAL
This application claims the benefit of U.S.
Provisional Application No. 60/094,800, filed July 31, 1998,
entitled, "Windshield With Coating having Primer For Edge
Seal".
The present invention is directed to monolithic or
laminated plies of glass and/or plastic where one or more of
the plies has one or more film coatings on or over one or more
plies or between plies and a material as an edge sealant which
optionally is also the adhesive primer.
TECHNICAL DISCUSSION
Glass and/or plastic laminates useful as
transparencies such as vehicle windshields have been affixed
to an opening such as an automotive body through the use of
various chemical compositions. Usually an adhesive primer is
placed on the marginal peripheral outer surface of the inner
layer of the transparency. Also an adhesive composition is
applied over the primer and the transparency is affixed to the
frame or rim of the opening of the automotive body. For
various laminates of glass and/or plastics edge sealing
chemical compositions have been applied to seal the width or
height edges of the transparency. This edge is the vertical
edge when the transparency has its longitudinal axis in a
horizontal position. Such edge sealing compositions like
poly(vinylidenefluoride) and the like for use with coated
transparencies such as windshields are disclosed in U.S.
Patent No. 5,122,403 (Roginski et al.)
As noted in U.S. Patent No. 5,122,403, windshields
can have coatings for various purposes such as to make
heatable windshields or to reduce infrared ("IR") and/or
ultraviolet ("UV") radiation from passing through the
transparency. These coatings can be applied within the
transparency on an inner major surface as to the transparency
of the outer plies of glass or plastic or on the inner or
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outer major surfaces of any interlayer plies'. With this
application of these coatings, the approach of the coating to
or at the vertical edge of the transparency can provide a
source or conduit for environmental conditions. For instance,
the coating can itself be corroded at the edge or provide for
corrosion from acid rain or road salt finding its way from the
vertical edge of the transparency into the laminated
transparency.
As noted in the '403 patent, hereby incorporated by
reference, edge sealants have been used to protect an exposed
edge portion of the coating from such degradation. Such an
edge sealant is a weather resistant material that can adhere
to the glass and interlayer material and will not react
adversely with the glass, interlayer material, or coating of
the transparency or an adhesive used to secure the
transparency in place.
The object of the present invention is to provide a
material that provides both a glass primer for adhesive
attaching of the transparency to a frame or rim of an opening
and a edge sealant to reduce degradation or corrosion of the
coating of a coated transparency from seepage or penetration
of the vertical edge of the transparency.
SUf~IARY OF THE INVENTION
The present invention is directed to a monolithic or
laminated transparency or glazing having one or more coatings
on one or plies of the transparency or glazing. The
transparency has one or more coatings and/or films on, over or
near an outer ply or between the outer plies of the
transparency on either the inner major surface of one or more
of the outer plies or on a major surface of one or more inner
plies located between the outer plies. Some of these types of
coatings may be susceptible to degradation or corrosion from
environmental conditions, factors, or forces such as salt
solutions and/or high humidity and/or acid rain and/or high
frequency of thermal variations between hot and cold
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temperatures. The sealing is provided from the presence of ate -
least one edge sealant or in other words sealing coating layer
of automotive clear coat coating compositions and/or
organosilanes, and/or organotitanates and/or organozirconium
compounds and/or adhesive primers over the environmentally
susceptible coating where the environmentally susceptible
coating is exposed to the environment. For a laminated
transparency like windshields and other automotive windows or
lites the edge sealant is applied on the vertical or lateral
edge where the plies of the transparent material and the
coating can be exposed to the environment. The application is
on sufficient amount of surface area of the vertical edge or
side of the transparency to seal the environmentally
susceptible coating or film in the transparency to retard
deterioration of such a coating or film. Optionally, the edge
sealant can also act as an adhesive primer on the marginal
edge portions of the major outer surface of the transparency
for attachment of the transparency to a support to act as a
glazing to cover an opening. Such adhesive primer type of
edge sealant include those that prime the glass or plastic for
adhesion to a substrate, that are compatible with adhesives
used for affixing the transparency to the support, and that do
not themselves degrade the coating of the transparency to any
great extent. Nonexclusive examples of such adhesive primers
include polyurethane and/or organosilane containing chemical
compositions. This edge sealant coating is one that
preferably is essentially free of polybutene copolymer,
fluoropolymer and butyl based compositions in a predominant
amount of the adhesive primer/sealer composition. These types
of polymeric materials are not necessary since the adhesive
primer itself or the other types of edge sealants of the
invention provides for edge sealing when disposed over the
lateral edge of the transparency.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a plan view of a laminated transparency
highlighting the marginal peripheral surface having the edge
sealant that is also present as the adhesive primer.
Figure 2 is a view taken along line 2-2 of Fig. 1
with the view to show the edge sealant along the lateral or
vertical edge and on the marginal peripheral surface of the
inner layer of the transparency.
Figure 3 is a side view of the top section of a
laminated transparency with a top lateral edge having the edge
sealant where the transparency can be used as an automotive
sidelite.
Figure 4 is similar to Figure 2 showing an
'alternative embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The description of the invention is taught in
connection with a laminated transparency comprised of two
glass plies bonded together by an interlayer of plastic, which
represents a typical windshield construction. Although it
should be understood that the invention can apply to
transparencies having two plastic plies or any combination
involving numerous glass and/or plastic plies or a single
(monolithic) ply of glass or plastic. For instance two
polycarbonate plies could be laminated together with or
without one or more layers of interlayer and these could serve
as the laminate suitable for edge sealing by the present
invention. The invention is not limited to an automotive
windshield but may be used in any transparency where there is
a problem of coating degradation along the exposed edge. For
instance the laminated transparency could be a laminated
automotive sidelite or even an automotive sunroof or even a
skylight for commercial or residential construction. Also the
ply or plies of a monolithic or laminated structure that are
glass can be annealed as for example with windshields or
tempered or heat strengthened, i.e. partially tempered, as for
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example sidelites. Suitable examples of transparencies that " -
have glass include such glasses as clear glass, float glass,
clear or tinted float glass of suitable compositions to enable
their production but preferably all of these have a base glass
which is a soda lime type of glass with different colorant
portions.
In Figures 1-3 the same numeric references are used
for similar components shown in the figures. Figures
("Figs.") 1, 2, and 3 show a transparency 20, which is
substantially transparent, and which includes an inboard or
inner glass sheet or ply 26, a plastic interlayer 24 and an
outboard glass sheet or ply 22. Non-exclusive examples of
glass suitable for plies 22 and 26 are described in U.S.
~Patent Nos. 4,746,347; 4,792,536 5,240,886 5,385,872; and
5,393,593, which are all herein incorporated by reference.
Interlayer 24 may be at least one layer of polyvinyl
butyral as is commonly used for laminated windshields or any
other suitable interlayer material known in the art. Suitable
examples of the latter are disclosed in U.S. Patent No.
4,704,179, hereby incorporated by reference. For instance the
poly(vinylbutyral) interlayers typically can have other
polymeric materials like polyurethane and/or plasticizers
and/or adhesion promoters like silane coupling agents such as
vinyl triethoxy silane (VTES) as more fully described in U.S.
Patent No. 5,028,658 hereby incorporated by reference. Other
additives that may optionally be present include: dyes,
ultraviolet light stabilizers, adhesion control salts,
antioxidants, and treatments from additives to improve
laminating efficiency as also noted in U.S. Patent No.
4,292,372, hereby incorporated by reference. Also
multilayered interlayers can be used where between the layers
there is one or more film layers of polyester or similar
polymers.
A coating 28 is preferably placed on a surface of
the transparency 20 that is not exposed, most preferably on
the inboard surface of the outboard glass sheet 22. Also with
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the present invention it is possible to place the coating on
monolithic transparency and coat the functional type of
coating with the edge sealant over the entire exposed surface
of the functional coating 28. Various coating configurations
may be applied as 28 to the major surface 30 depending on the
desired properties to be added to the transparency 20. The
coating can be of one or more films in one or more layers
including use of existing film material such as polymeric
based films with or without additional coatings. The latter
is as opposed to forming a coating or film on the glass from
one or more film forming compositions placed on the glass.
The one or more coating films) can be those that function to
provide solar control properties, optical properties,
electroconductive properties, semiconductor properties,
aesthetic properties, and the like known to those skilled in
the art. The films of the coating can be applied over the
substrate as thin films such as those applied by pyrolytic
application, chemical vapor deposition, and sputtering
techniques such as magnetron sputtered vacuum deposition
(hereinafter "MSVD") or electron beam (EB) deposition. Any of
these techniques that are well known to those skilled in the
art can be used. For example, although not limiting in the
present invention, suitable electroconductive coatings that
are useful are those similar to the coatings and films
disclosed in U.S. Patent Nos. 5,122,403 (Roginski et. al.) and
4,610,771 (Gillery) which are hereby incorporated by
reference. These patents disclose coatings to reflect IR
radiation and/or provide an electroconductive film for a
heatable windshield. These coatings generally include one or
more silver films between pairs of zinc stannate films, each
of which may be applied sequentially by magnetron sputtering.
An optional opaque border 32 (shown only in Fig. 2),
such as a ceramic enamel, may be applied about the marginal
edge~of the transparency 20 in any well known manner, e.g.
screen printing and the like, and heated to bond the border 32
to surface 30. For instance a suitable opaque material is
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black frit layer or coating like a ceramic frit layer that
covers and conceals at least a portion of the inner surface
30. The area or pattern of the inner surface 30 which
receives opaque coating 32 will generally include a region
from peripheral edge 36 of the transparency inward. The
inward distance can be around two or more inches or a
sufficient distance to conceal from the exterior any edge
sealant that also functions as an adhesive primer and forming
the edge sealant as adhesive material for attaching
transparency 20 to the vehicle. The ceramic frit coating 32
includes a pigment of a desired color,. preferably a dark tint
such as black or the like. One ceramic material used to form
the opaque black, ceramic frit coating 32 is manufactured by
~Cerdec Corporation-Drakenfeld Products located in Washington,
Pennsylvania. This is an example of the meaning that the
transparency is substantially transparent, that is a major
portion of the transparency for a vision area is transparent
but other portions of the transparency may have coatings so
that a portion or portions are not transparent or completely
transparent. Another example is that transparencies other
than those that are windshields and front side lites or panels
for motor vehicles which are required by law to have a minimum
luminous light transmittance value (LTA) can be darker as in
privacy glass. Such privacy transparencies as used for rear
lites and rear side lites on trucks and vans are still
substantially transparent even though some of them may have
very dark tints and/or coatings.
In Figs. 1 and 2 after coating 28, the interlayer 24
as one or more layers is positioned between the bent glass
sheets 22 and 26 and the entire assembly is laminated in any
convenient manner well known in the art to form a unitary
structure. As an alternative, the coating 28 may be applied
to a flat glass ply 22 which is subsequently bent to a desired
configuration.
For the surface of the inboard ply of glass in the
laminate that is to be affixed to the support, an edge sealant
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34 (as shown in Fig. 2) is applied along the marginal
peripheral surface 35 (as shown in Fig. 1) and to as much of
and preferably all of the peripheral lateral or vertical edge
36 of the laminated transparency 20. In this manner coating
28 serves as an edge sealant to hermetically seal exposed edge
38 and isolate it from the environmental at least at the time
of manufacture and for a suitable use period thereafter.
Otherwise for the present invention where the edge sealing
coating will not be used as the adhesion primer or where the
glazing of the transparency does not include an adhesive
attachment, the edge sealant 34 is present on most preferably
all of the lateral surface 36 of the transparency. However
the sealant may not extend, but preferably does extend, to the
'peripheral marginal_.portion of the major surface of the
transparency as at 35.
Fig. 3 shows a laminated transparency as an
automotive sidelite 20 including a first ply 22 having an
outer major surface 23 and an inner major surface 30, a
functional coating 28 deposited on, over or formed on at least
a portion of the major surface 30, an interlayer 24 and a
second ply 26 having an inner major surface 25 and an outer
major surface 29. Usually the outer major surface 23 faces
the exterior of the vehicle, and the outer major surface 29
faces the interior of the vehicle.
The first and second plies 22 and 26, respectively,
are each preferably made of a substantially transparent or
translucent material, as noted above for Figs. 1 and 2. For
sidelites, the thickness of the first and second plies are
preferably less than about 3.0 mm, more preferably less than
about 2.1 mm and even more preferably in the thickness range
of about 1.6 - 1.8 mm. The edge sealant 34 results from the
edge sealant composition applied to the top lateral edge 36.
In addition the edge sealant composition can be placed or
formed on the other lateral edges of the sidelite (not shown
in Fig. 3), i.e., the sides and the bottom as the transparency
20 is positioned in the glazing.
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The edge sealant whether or not it has the ' -
capability to function as both adhesion primer and edge
sealant can be a one or two component application. The primer
compounds generally include organosilanes and amino silanes
such as those available from Dow Coming, Essex Specialty
Products Inc., General Electric, and Lord Chemlock, and
polyurethane-containing and/or automotive aqueous-borne or
solvent-borne clearcoat compositions. Suitable examples
include diamino-tri-methoxy silanes available under the
designations Lord Chemlock 134/144. Adhesion primers, such as
the adhesion promoters described in U.S. Patent Nos. 4,839,122
and 4,761,916, hereby incorporated by reference, can be used.
t3seful commercial materials include "Betaseal~ Glass Primer
'435.18", "Betaseal~ Glass Primer 435.20A" and "BetasealO Glass
Primer 435.21", produced by Essex Specialty Products, Inc.,
Auburn Hills, Michigan. Other useful edge sealants which
optionally also are adhesion primers include polyurethane
compositions of U.S. Patent No. 5,623,044, hereby incorporated
by reference, comprising (1) a urethane prepolymer having an
isocyanate functionality of at least about 2.0 and a molecular
weight of at least about 2,000; and (2) the reaction product
of a secondary amino- or mercaptoalkoxy silane and a
polyisocyanate having an average of at least one silane group
and at least one isocyanate group per molecule and a molecular
weight of less than about 2,000. Other silanes not limited to
diamino or tri-methoxy forms may also be suitable. A second
group of edge sealing coatings and optionally adhesion primers
are organotitanates or zirconium coupling agents such as
available from Kenrich Petrochemical Inc, of Bayon, NJ. Such
coupling agents as with the organosilanes have the capability
of reacting with organic compounds and inorganic materials
including compounds and surfaces such as glass and the like.
Generally these coupling agents have moieties for reaction
with organic compounds and moieties for reaction with
inorganic materials.
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Alternatively, or in addition to an adhesion prime, -
one or more primers or single-component urethane adhesives may
be used as the edge sealant and primer. Nonexclusive examples
of these include urethane based, isocyanate-rich, moisture-
s curable, urethane prepolymers such as Morton Yokohama MS-90
available from Morton International of Ridgewood, IL, or Essex
435.20A. Additional examples of edge sealant with or without
primer functionality include but are not limited to Essex
435.32, for applications in which the substrate to be bonded
to glass is metal or plastic.
Another type of edge sealant are those from
thermosetting type of automotive clear coat compositions. The
automotive clear coat compositions are those typically used in
color-plus-clear applications for painting motor vehicles. In
a color-plus-clear or base coat and clearcoat type of
application, a composite coating is applied to a substrate.
The clear coat is the transparent second film-forming
composition usually applied as the top coat over the base coat
and usually substantially unpigmented in that only minor or
trace amounts of pigments may be present but the coating
remains substantially transparent. The clear coat
compositions include curable film-forming compositions having
such film forming polymers as polyurethanes, polyanhydride-
containing materials along with a polyhydroxy-containing
material; acrylosilane polymers along with an acrylic polyol
polymers, and optionally along with alkylated aldehyde
condensate crosslinking agents such as melamine-formaldehyde;
and polyisocyanate and a polymer having at least one group
that is reactive with isocyanate such as a polyol and/or
acrylic polyol. These compositions are formulated as either a
one component or two component system. In the former
formulation capping agents can be used as known in the art to
delay reaction and in the latter case one component is at
least one film forming polymer and the second component is the
crosslinking material for the polymer. Of course the order of
polymer and crosslinker can be the reverse of this. Also
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copolymers and polymer blends of these polymeric materials calf -
be used such as acrylic polyurethane copolymers and blended
acrylic and polyurethane polymers. All of these compositions
are well known to those skilled in the art of clear coat
automotive compositions. These and other types of coating
compositions useful in forming the edge sealant are described
in U.S. Patent No. 5,891,981 (Mauer et. al.); and the coating
compositions and film forming polymeric materials of U.S.
Patent Nos. 5,279,862; 5,286,782; and 5,545,824 all hereby
incorporated by reference for their disclosures of such
polymeric materials and compositions.
Other suitable examples of commercially available
clear coat compositions that may be the used for the edge
'sealant and the primer include PPG NCT clear coat and PPG
CONCEPTO DCU 2020, DCU 2021, and DCU 2042 premium two-
component coatings, and Stratoclear DCU 2082 all available
from PPG Industries Inc. Pittsburgh, PA.
Another example is the fast drying polyurethane type
coating described in United States Patent Application entitled
~~Fast Drying Clear Coat Composition", Serial No. 09/086919,
filed May 29, 1998, and also filed as a Patent Cooperation
Treaty application as WO US99/09755 both disclosures of which
are hereby incorporated by reference.
The composition applied to the glass surface for
forming the edge sealant can form a coating layer having a
thickness such that the entire surface of the area of the
glass to be bonded, or substantially so, is wetted by the
composition for forming the edge sealing coating. A suitable
thickness range for the edge sealant 34 can be from about 0.01
mils to about 3.5 mils (0.254 microns to 0.089 mm ) preferably
0.5 mil to 1.5 mil (1.27 to 3.81 microns). Any excess amount
of edge sealant, whether or not used also as a primer, on the
transparency to be bonded can be removed by allowing solvents
in those materials to flash off. Sufficient flash off was
found to occur at ambient temperatures in a period of only
from about 5 seconds to about 15 minutes. Preferably the
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curable edge sealants cure at ambient conditions or slightly"
elevated temperatures but at a temperature that is less than
the glass transition temperature of the interlayer 34.
One or more, preferably two, coating layers of any
one or a combination of the edge sealants are applied to the
transparency substrate and/or other substrates to be bonded
thereto prior to bonding. A preferred combination is to
utilize an amino silane adhesion promoter, such as Essex
435.18 silane coupling agent, adjacent the glass surface,
followed by a layer of a single-component urethane primer,
such as Essex 435.20A primer, deposited on the first layer of
the edge sealant and primer. An adhesive for affixing the
substrate to the support would be deposited on the primer
'layer or as noted above the primer can be one that is a one
component primer and adhesive.
The edge sealant can be formed on the transparency
by application of an edge sealant composition by dipping,
brushing, roll coating or like processes known to those
skilled in the art. The composition can be applied to the
transparency before or after any lamination step. Fig. 2
indicates the application after lamination.
When the edge sealant composition is applied before
laminG~ion, it may be applied about the peripheral lateral
and/or marginal edge of outer glass ply 22 as indicated in
Fig. 4. In particular after coating 28 has been applied to
glass ply 22, the edge sealant composition may be applied to
the marginal area 38 and peripheral edge 40 of glass ply 22 to
form edge sealant 34 to seal the edge of the coating 28 and
protect it from the environment and chemical attack after
lamination. When the edge sealant also serves as the primer
or adhesive and primer for affixing the transparency as a
glazing to an opening in a frame, the edge sealant would
additionally be applied to cover the laminate transparency
similar to that of Fig. 2 hereof. Other alternative
arrangements of the edge sealant with the laminate as depicted
in the Figures of U.S. Patent No. 5,122,403, as incorporated
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herein by reference, can be used with the edge sealant of this -
invention.
Additionally retarding of the deterioration and/or
corrosion of the coated transparency by the environment is
accomplished by one or more of the following conditions. The
functional coating 28 of Fig. 1 of the laminate has fine
abrasions or scratches along the peripheral marginal area or
border of the major surface of the sheet or ply for the
transparency 20 such as 35 of Fig. 1. The abrasion marks are
place in the border area before the heating of lamination of
the transparencies having the functional coating 28. The fine
abrasion is similar to that accomplished by hand rubbing the
marginal or peripheral area of coating of the transparency
'with an abrasive article such as an abrasive sponge like a
Scotch-Brite pad approximately 6 mm wide. Such useful
abrasive articles include Scotch Brite pad ultra fine, Scotch
Brite pad light 20bx, maroon Scotch Brite pad, and similar
abrasive grit sandpapers and the like. Also the
transparencies with the functional coating can be laminated at
a higher temperature than the conventional temperature of
lamination. Non-exclusive examples of such a higher
temperature is up to about 50°F higher than conventional
temperatures. Also it is preferred that the structure of the
laminate is with the interlayer flush with the peripheral
lateral edge of the laminate along with the ply or sheet that
has the functional coating.
The method and apparatus for forming laminated
transparencies can be those described in U.S. Patent No.
5,698,053 (Carroll et. al.) hereby incorporated by reference.
EXAMPLE 1
Windshields Examples for Edge Sealant and
Laminate Construction and Process
A total of 126 laminates (12 inch by 12 inch) were
fabricated under similar controlled conditions. The samples
were submitted to two different corrosion tests and the edge
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stability number (ESN) measured. Each set of samples was
submitted to the two corrosion tests. One test (Test A) was
the acid salt bath submersion at a pH 4.0 (H2S09) and 5~ NaCl
solution at 130°F for 300 hours. The second test (Test B) was
the a salt fog test, which is a cyclic test at pH 4.0 and 1$
NaCl for 60 cycles (days). These are similar to American
Society of Testing Materials (ASTM) tests B117 and G 85 annex
1, 2, 3, and 5. The edge stability number (ESN) is a ranking
system to grade edge damage to laminates. It gives greater
weight to those areas of deeper corrosion by a factor of the
power of 2. An ESN number of zero would indicate no corrosion
and an ESN number of 2,500 would indicate the entire perimeter
of the windshield was corroded to a depth of 6 mm. The ESN is
the metric to rank those processing parameters that impact
corrosion of the laminates the most. Parameters investigated
include interlayer location in relation to the glass in a
laminate (scant -interlayer does not reach to the edge of the
laminate and does not completely cover the glass surface) or
(flush -the interlayer matches the surface area of the glass
in the laminate), interlayer adhesion (two different types of
interlayers known as "RC" and "RB"), and coating scratches
before heating.
300 Hour Acid Salt Bath test (Test A)
The test results of the 300 hour acid salt bath are
as follows. The laminate samples having two coating layers of
edge sealant and having the interlayer flush at the edges of
the laminate were the best performing with no corrosion. The
laminate samples having excess PVB interlayer construction
with two coats of edge sealant were the next best performers
with an ESN of approximately 25. The laminate samples with a
single coat of edge sealant and flush interlayer construction
had an ESN of less than 50. The laminate samples with just a
single coat of the edge sealant and excess PVB interlayer
construction had an ESN of slightly greater than 50. The
control windshield laminate was a commercial windshield coated
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with Sungate~ coating which had an ESN of slightly greater
than 150. The laminate samples having two coat edge sealant
with scant interlayer construction had about the same
performance as the control of around 150 for ESN whereas the
laminates with single coat of edge sealant had an ESN
approaching 300.
Test B
Results from the 60 day salt fog test on the Essex
primer edge sealant in conjunction with the acid/salt bath
test of Test A, indicated the effectiveness of one and two
coat application of the edge sealant in the prevention of
corrosion on scant, flush, and excess interlayer
constructions. Salt--fog results concur with the acid/salt
bath results and show that the edge sealant and primer system
does work to reduce the corrosion rate and, hence, the amount
of corrosion versus a laminate with an unsealed edge. The
variations in the interlayer material can impact on the
robustness of the laminated product. These tests also
indicate that the two coat application of the edge sealant
that also acts as the adhesive primer minimize corrosion. The
results of the experiment show flush PVB interlayer
construction, before heat scratches, and high firing
temperature as being variables that produced the least amount
of corrosion. The flush construction more than likely is
better because of the difficulty in sealing the edge when the
interlayer is scant. Scratching the functional coating has
the "good" effect in preventing corrosion when done before
heating the laminate. Because the test is a submersion test
it is believed the scant PVB interlayer ranking is skewed
because the corrosion was measured from the edge of the glass
and not from the edge of the PVB interlayer where the
corrosion actually starts to penetrate the laminate. The
scant PVB interlayer construction acts as a strong variable
because of the tendency for those areas of the laminate to
collect moisture.
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EXAMPLE 2
Types of Edge Sealant
A 3,200 hour QUV test was completed to determine if
various edge sealant compositions would affect the PVB
interlayer in a laminate. Laminates (3 inch by 12 inch) using
polyvinylbutyral ("PVB") interlayer from a Solutia were
prepared with the following edge sealant compositions:
Material of U.S. Patent No. 5,122,403
PPG CONCEPT~ 2020 clear coat
PPG CONCEPT~ 2021 clear coat
Essex Betaprime 5004 material
On each laminate one edge was left exposed to the UV
light and the other edge was covered with lace to simulate a
real windshield condition. A sample with no edge sealant was
used as a control. Results were recorded after 500; 1,000;
1,500; 2,000; 2,500 and 3,200 hours. Any delamination defects
were recorded as maximum depth of the defect, average depth of
the defect, percentage of total length, and average area of
the defect.
The results after 3,200 hours for these edge sealant
compositions were:
Edge Sealant Composition Result
material of U.S. Patent No. the most defects in the PVB
5,122,403 interlayer of this test; the
most delamination of the
samples but the maximum depth
was only 1.5 mm
PPG CONCEPT 2020 clear coat no defects in the PVB
interlayer regardless of being
covered by the lace or not.
PPG CONCEPT~ 2021 clear coatvery little delamination
Essex Betaprime 5004 materialvery little delamination
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These results showed no significant interaction between these
edge sealants and the Solutia PVB.
The edge sealant with the Essex urethane primer was
tested as a single and double coating application approach.
The one step glass primer from Essex coded 435.26 was tested
versus double step 435.18 and 435.20A primers. However, two
different batches of the 435.26 material failed to provide
adequate adhesion under a variety of conditions. However
acidic modified Essex 435.18 material as a one step
application shows better retention of adhesion when priming is
done at low humidity conditions versus high humidity
conditions. Testing for one week water immersion at 50°C or in
a 500 hour carbon arc Weatherometer was also done with the
Morton-Yokohama primer MS-90 single step primer and Essex 5001
single step urethane primer. The Yokohama primer and Essex
5001 primer passed with excellent results. This indicates
that a one step primer can be used as the sealant as well as a
two step Essex primer. Primer application was done under low
and high humidity conditions, with results showing less
cohesive failure at low humidity which is undesirable.
wwunr c~ ~a
SIDELITES and Edge Sealant and Process
Four edge sealant compositions were tested as edge
sealant for the laminated sidelites having an
electroconductive coating. These compositions were four types
of PPG Coatings & Resins automotive 2K (two pack) clear coat
compositions Which included: PPG CONCEPT~ 2020, PPG CONCEPT
2021, PPG 2082, and PPG 2042 products. Edge sealant
application methods were also varied in order to determine if
application prior to lamination has an effect on corrosion.
Samples were made with each of the edge sealants on full size
sidelites with electroconductive coatings. The sidelites were
laminated using 1.8 mm SL1NGATE~ electroconductive coated SOLEX
glass laminated with 30 mil (0.76 mm) PVB interlayer to 1.8 mm
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SOLEX glass. The glass is available from PPG and the two
types of PVB interlayer were used for this test are available
from DuPont as B180SL and Solutia as RB-41. These samples
were tested in two separate exposure tests: the 300 hour
acid/salt bath (Test A above) and the 300 hour acid rain salt
fog test (Test B above). The corrosion was measured every 100
hours to determine the effectiveness of these materials to
protect the electroconductive coating.
Results of the acidic salt bath testing show a small
amount of corrosion (ESN 0 to 14) for edge sealed, and
unprotected areas.
As in Example 1, a 60 day cyclic salt fog test for
the four types of samples indicated that for sidelites the
before heat scratches and higher temperature of processing the
laminates were influential in retarding corrosion. Also the
test indicated that Scant PVB interlayer construction was
detrimental to corrosion resistance. The acid rain solution
of pH 3.5 and cyclic fog, dry, humidity, and dry sequence
produced ESN numbers similar to those of the acid salt bath
test. The cyclic tests were conducted in a manner similar to
those of GM 9540P/B and SAE J1563.
Q-fog acid rain corrosion Test
A total of five coated sidelite samples with edge
sealant were placed on exposure in the Q-fog acid rain
corrosion solution (pH 3.4) in a Q-fog environmental chamber
to see if degradation occurs. These five samples involved
application of different edge sealants to three sides of a
laminated sidelite with an electroconductive thin film
coating. The edge sealant compositions that were used
consisted of 1) and 2) hot melt ethylene vinyl acetate ("EVA")
3M3792 and 3M3764, 3) and 4) PPG CONCEPT~ DCU 2021 and DCU
2042, and 5) PPG Stratoclear DCU 2082. Also one sidelite
having an electroconductive coating with no edge sealant was
also placed on exposure as a control.
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The samples completed the 312 hours of exposure.
The following samples showed no degradation present at the
protected edges: hot melt EVA 3M3792, PPG CONCEPT DCU 2021,
and DCU 2042. However, the hot melt EVA 3M3792 did show signs
of sealant material coming off the laminated edge of the
sidelite. PPG Stratoclear DCU 2082 and EVA 3M3764 did reveal
degradation in the edge sealed area, and the edge sealant was
coming off the edge of the laminated sidelite. The laminated
coated sidelite with no edge sealant revealed degradation in a
couple of areas (1.5 mm).
Q-fog 60 cycle acidic salt fog test
The five coating samples with edge sealant also were
'placed on exposure in the Q-fog 60 cycle acidic salt fog test.
The edge sealant composition was applied to three sides of a
laminated sidelite with electroconductive coating. The edge
sealants used were hot melt EVA 3M3792 and 3M3764, PPG
CONCEPT~ DCU 2021 and DCU 2042, and PPG STRATOCLEARTM DCU 2082.
Two sidelites with no edge sealants were also placed on
exposure as experimental controls.
The initial 60 cycle salt fog test showed positive
results for preventing corrosion of the SUNGATE coated glass
where the edge sealant was applied thoroughly to the edge.
Although all of the samples on this initial round of tests
showed some degree of corrosion, close examination of the
samples revealed that even small areas of edge sealant voids
would permit the corrosion to start. These small voids in the
edge sealant application can occur at areas where there is a
discontinuity in the windshield edge such as glass ply or PVB
interlayer mismatch. Condition of the windshield edge,
particularly the relationship of the PVB interlayer to the
glass edge, is a factor, which can affect the efficiency of
the edge sealant to prevent corrosion. It was noted that
these types of edge conditions did not permit uniform coverage
of the sealant using a one coat wiping action with a standard
foam applicator.
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Outdoor Exposure Testing
The first six month evaluation for PVB interlayer
compatibility with SUNGATE~ 100T coated glass in a laminated
sidelite for field exposure samples was completed for two
southern location exposure sites, Florida and Arizona. Two
30 mil (0.76 mm) PVB interlayer types, DuPont B180SL PVB and
Solutia 8841 PVB, were tested for eight laminated sidelites.
A total of four (two laminated with each PVB type) sidelites
are on exposure at different locations. The configuration of
the laminated sidelites are: 2.1 mm clear glass coated with
SUNGATE~ 100T coating/30 mil (0.76 mm) PVB/2.1 mm SOLARGREEN~
glass. There was no PVB interlayer damage or corrosion
.observed for the first six months of exposure.
