Note: Descriptions are shown in the official language in which they were submitted.
CA 02308919 2000-05-19
ROOFING MATERIAL WITH ENCAPSULATED FIBROUS MAT
Field of the Invention
The present invention is in the field of roofing materials. More particularly,
the present
invention is in the field of roofing membrane materials incorporating a
fibrous mat to provide
traction to roofing installers during construction of the roof.
Background of the Invention
Asphalt based roofing shingles are presently installed on approximately eightv
percent of the
homes in the United States. In areas where snow accumulates, roof shingles can
develop
leaks as a result of ice dams which can form along the eaves of a roof. Ice
dams form as the
result of a differential temperature which occurs between the eaves of the
roof and the interior
sections of the roof. The temperature differential occurs when heat rises into
the attic space.
Under certain temperature conditions, snow collected on the roof surface will
melt along the
upper interior portions of the roof and then freeze when the liquid snow-melt
reaches the
cooler eave section of the roof. As can be seen in FIG. 1, the result is that
a pool I of liquid
water can form between the roof surface 2 and the ice dam 3. The ice dam 3
prevents the
water from reaching the gutter 4 and draining away. Ultimately, the liquid
water I can leak 5
through the roof surface 2, causing interior water damage to the structure.
Ice dams can also
occur as a result of frozen slush accumulating in gutters, also causing liquid
to collect and
leak through the roof.
In a typical roofing installation using asphalt shingles, an underlayer is
first applied to the
plywood deck of the roof. The underlayer may take the form of an asphalt
saturated paper
CA 02308919 2000-05-19
which is useful as a waterproofing member. Roofing shingles are applied on top
of the
underlayer with the seams of adjacent rows positioned in an offset
relationship. In practice, a
starter row or strip is begun at the roof eaves using self-sealing shingles.
The end of the first
shingle in the strip is trimmed such that, when it is placed on the deck, the
cutouts of the first
course of shingles will not be placed over the starter strip joints. The
starter strip and the
shingles are nailed to the eaves. Successive rows of shingles are then secured
to the deck or
roof using nails.
To ensure maximum protection against ice dams, membranes or metal flashing is
installed
wherever there is a possibility of icing, such as along the eaves of the roof.
As noted above,
ice dams are formed by the continual thawing and freezing of melting snow, or
the backing
up of frozen slush in gutters, which force water under the roofing, thereby
causing damage to
a structure's ceilings, walls, and insulation. The ice damming problem is most
acute on low-
slope roofs; that is, roofs with a slope of two inches (5.08 cm) to four
inches (10.16 cm) per
foot (30.48 cm).
Traditional eaves flashing has either been 50-pound coated felt or two layers
of 15-pound
saturated felt cemented together. The term "pound" is defined as the weight of
the felt
required to cover an area of 108 square feet. Typically, the asphalt used in
the fifty-pound
felt is not modified with rubber, and after aging, will not form a good seal
around nails.
Additionally, the installation of two layers of 15-pound saturated felt
consumes undesirable
amounts of time and also will not seal around nails.
The use of self-adhesive products, such as ice and water protective membranes,
has now
become commonplace. A major problem with these products is that they are
slippery,
especially when wet or covered with frost. Slippery surfaces upon roofs create
significant
safety hazards for roofing installers, especially since such surfaces tend to
be at least one
story above ground level.
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In an attempt to reduce the slippery nature of ice and water protective
membranes, separate
methods have been developed. In the first method, granules have been embedded
in an
asphaltic composition or in polyethylene sheeting which is either embossed or
coated. When
positioned on an upper surface of the membrane, the granules provide a high-
traction surface
upon which a roofing installer can walk. Such membranes also offer
reinforcement and/or
structural integrity, and allow lap sealing. Unfortunately, the granular
surfaced materials
suffer from disadvantages in that the granules cannot all be embedded into the
asphalt
material, thereby providing some degree of loose granules which can render the
surface
slippery. Additionally, since the granules roughen the membrane surface, it
becomes
necessary to cement overlaps in order to render them watertight. Finally, the
granules add
weight to the membrane which increases handling difficulties and freight costs
associated
with the membranes.
As for the membranes which employ polyethylene sheeting, the polyethylene
surface tends to
be quite slippery, thereby raising safety concerns. Furthermore, membranes
which use
polyethylene sheeting tend to be very flexible, rendering them hard to handle
and apply.
In some applications, a problem has developed in which granular surfaced
membranes have
adhered to the overlying shingles. The roofing membranes described above are
intended to
be adhered to the underlying plywood of the roofing deck and not to the
overlying shingles.
If the membrane adheres to both the shingles and the roofing deck, removal of
the shingles
requires that the plywood decking be removed as well. This is very undesirable
as it adds
significant costs and complexity to the shingle repair.
Thus, a need exists for a membrane material which provides a highly non-slip
surface,
excellent lap sealing, structural integrity and lower weight. A need also
exists for a
membrane material which is resistant to adhering to the shingle portion of the
roof.
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CA 02308919 2000-05-19
Summary of the Invention
The present invention in accordance with an aspect thereof provides a roofing
membrane material which comprises:
a) a fibrous mat having an upper surface and a lower surface;
b) a non-adhesive asphalt coating which encapsulates the fibrous mat; and
c) an adhesive asphalt coating applied to the lower surface of the
encapsulated mat.
In accordance with another aspect the present invention provides a method for
making a roofing membrane material which comprises the steps of:
a) providing a web comprising a fibrous mat having an upper surface and a
lower
surface;
b) encapsulating the web within a non-adhesive asphalt coating; and
c) forming an adhesive asphalt coating on the lower surface of the
encapsulated mat.
As described the present invention relates to roofing membrane materials
having a
fibrous mat surface which provides traction, structural integrity and lap
sealing
capabilities. More particularly, the present invention relates to a roofing
membrane
material which may have an adhesive surface provided by an adhesive rubberized
asphalt layer and non-adhesive surface provided by a woven or non-woven
fibrous
mat encapsulated within a non-adhesive asphalt coating. The adhesive
rubberized
asphalt layer may be very adherent and may provide excellent adhesion of the
membrane to a roof deck, while the encapsulated fibrous mat may provide a
surface
having excellent traction and lap sealing characteristics. An acrylic and low
molecular
weight polyethylene composite or other polymers that adhere to the asphalt and
provide a non-slip surface may also be coated onto the non-adhesive surface to
enhance its non-adhesive characteristics and provide traction. In one
preferred
embodiment, a layer of talc is applied to the acrylic layer to provide
additional
coverage of the asphalt. In another preferred embodiment, traction is further
enhanced by providing granules of a particulate material embedded in the
acrylic
coating. The combination of the acrylic and the underlying non-adhesive
asphalt
prevent shingles from adhering to the membrane, while the material, with or
without
talc or granules, provides a high traction surface. The preferred material for
forming
the fibrous mat is fiberglass or polyester.
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CA 02308919 2008-04-10
For preventing multiple layers of the membrane from adhering to one another
during
shipping and storage, a release sheet can be applied to the lower, adherent
surface
of the rubberized asphalt layer. As a result of the release sheet, when the
membrane is rolled, or when several layers of the membrane are stacked
together,
the release sheet is interposed between the sticky lower surface of the
rubberized
asphalt and the adjacent traction layer. By interposing the release sheet,
adhesion
between subsequent layers of the membrane material is prevented. Of course,
during application to a roof surface, the release sheet is removed, thereby
allowing
the sticky underside of the membrane to adhere to the roof.
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CA 02308919 2000-05-19
One object of the present invention is to provide rubberized asphalt roofing
product which
can be applied along the eaves of a roof to serve as a water infiltration
barrier for the
overlying shingles.
Another object of the present invention is to provide a roofing membrane
having a non-slip
surface for the safety of roof installers.
A further object of the invention is to provide a roofing membrane that will
not adhere to
shingles, thereby allowing the shingles to be easily removed and replaced, if
necessary.
These, and additional features and advantages of present invention, will
become more
apparent from the following detailed description when taken in conjunction
with the
accompanying drawings.
Brief Description of the Drawinj!s
FIG. 1 is a side elevational view of a portion of a roof showing an ice dam.
FIG. 2 is a sectional view of the roofing membrane of the present invention.
FIG. 3 is a schematic representation of one process for manufacturing the
roofing
membrane of the present invention
FIG. 4 is a perspective view of the eaves of a roof having the membrane of the
present
invention, and several shingles, applied thereto.
FIG. 5 is a side elevational view of the portion of the roof shown in FIG. 4,
with the
shingles removed for the purpose of clarity.
Detailed Description
The present invention relates to self-adhesive membranes which have been
developed to
eliminate problems associated with ice dams. The inventive membranes have a
woven or
non-woven fibrous mat which is encapsulated within a relatively non-adhesive
asphalt
composition. One surface of the coated mat is provided with an acrylic coating
which
CA 02308919 2000-05-19
optionally contains finely-ground particles of talc or other mineral
materials. The other
surface of the encapsulated mat supports a rubberized asphalt layer that
adheres directly to the
wood deck of a roof. Roof shingles may then be applied directly over the
membrane. The
membrane prevents water entry into the structure by adhering to the deck and
sealing around
the nails which are used to hold the shingles to the roof deck. However, since
the membrane
has been provided with a relatively non-adhesive asphalt upon which is coated
an acrylic
material, shingles placed against the membrane do not adhere to it, either
upon placement or
after an extended period of time.
As noted previously, two types of self-adhesive membranes are currently used
to solve the ice
dam problem: granular surfaced membranes and polyethylene surfaced membranes.
Typical
polyethylene surfaced products are either embossed or coated to reduce the
slip hazard to the
roofing installer. Since the roofing installer must stand on the membrane
during its
application to the roof deck, surface traction on the membrane is a
significant safety issue.
The present invention increases surface traction on the membrane by providing
a high-
traction fibrous mat on the upper surface of the membrane. The mat may be high
traction by
its own nature, or it may be provided with a non-slip coating embedded at
least on its surface.
The fibrous mat may be any of a wide variety of woven or non-woven materials.
In one
preferred embodiment, the fibrous mat comprises a non-woven fiberglass mat. In
another
preferred embodiment, the fibrous mat comprises a non-woven polyester mat. The
mat is
preferably saturated with a material which comprises 50% oxidized asphalt and
50%
limestone filler, and then coated with a polymeric composition, such as an
acrylic
composition, and talc. The asphalt coating tends to fill in gaps and porous
regions in the mat
through which leaks could otherwise occur in sections of the membrane which
are lapped.
The acrylic provides or enhances a high traction walking surface. In addition,
the acrylic acts
as a binder to strengthen the membrane. Polymeric strengthening of the
membrane is desired
because the membrane must meet an ASTM tensile strength requirement of 24
pounds per
inch. The strength of the polymer thereby allows a lighter glass mat to be
used.
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CA 02308919 2000-05-19
When using a fiberglass mat, a non-woven fiberglass weighing between one to
three pounds
per hundred square feet (about 0.05-0.15 kg/m'), preferably about two pounds
per hundred
square feet (about 0.10 kg/m'), is used. The polymeric composition that is
applied to the
asphalt-saturated mat can be selected from any of a wide variety of polymeric
materials. For
example, polyurethanes, polyethylenes, latex, ethylene vinyl acetate (EVA),
acrylic polymers
and polyesters all may be used. In one preferred embodiment, the polymeric
composition is a
composite of an acrylic and a low molecular weight polyethylerie. In another
preferred
embodiment, the polymer comprises a UV curable polyurethane. In still another
preferred
embodiment, the encapsulated mat is provided with a coating of polyethylene.
It should be noted, however, that the invention is not intended to be limited
to polymeric
coated embodiments. Rather, any of a wide variety of fibrous mat materials,
including, but
not limited to, woven and non-woven polyesters and polypropylenes, with or
without
polymeric coatings, may be used. For example, in one preferred embodiment, the
mat
comprises a non-woven polyester, preferably weighing between about 2.22 to
about 4.88
pounds per hundred square feet, (about 0.11-0.24 kg/m') encapsulated in the
asphalt
composition.
Likewise, the invention is not intended to be strictly limited to embodiments
in which the
fibrous mat is encapsulated in an asphaltic material. Rather, in one
embodiment, the mat may
be encapsulated within a polymeric material such as ethylene vinyl acetate
(EVA) or a
polyurethane. Such an encapsulated mat would still employ the adhesive asphalt
layer to
adhere the membrane to the roofing deck, and may optionally include the
acrylic or similar
coating on its upper surface and/or a finely-ground mineral layer such as
talc.
In still another embodiment, the membrane comprises a mat formed of a non-
woven polymer,
such as polyester that has its lower surface coated with a non-adhesive,
filled asphalt. An
adhesive asphalt is then coated onto the non-adhesive asphalt layer in order
to provide a
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CA 02308919 2000-05-19
surface which readily adheres to the roofing deck. As before, the non-adhesive
filled asphalt
preferably comprises a composition of 50% oxidized asphalt and 50% limestone
filler. This
embodiment does not require a polymeric or finely-ground mineral coating on
its upper
surface, although, if desired, one or more of those may be employed.
In a broad sense, the present invention comprises a roofing membrane material
having a
traction layer formed by a fibrous mat encapsulated within a relatively non-
adhesive asphalt.
The encapsulated mat further includes, on one surface, an adhesive asphalt
coating such as
that described below. The relatively non-adhesive asphalt material, in one
preferred
embodiment, comprises an oxidized asphalt and limestone filler. These two
components may
be present over a wide compositional range, but a ratio of 50 % by weight of
each is
preferred. The mixture of oxidized asphalt and limestone filler is desirable
in that it is
relatively inexpensive, has excellent high temperature stability due to its
Ring and Ball melt
point of about 225-250 F (about 107-121 C), and helps to create a non-stick,
but safe
walking surface. This is important because, especially in the case of EVA-
coated fiberglass,
gaps in the mat may be present. Using a method that will be described in
detail below, the
relatively non-adhesive asphaltic layer is applied to the fibrous mat in a
manner such that it
infiltrates completely through the mat's thickness. An acrylic coating is
provided on one
surface of the encapsulated mat, while an adhesive asphalt layer is provided
on the other
surface of the encapsulated mat.
The adhesive asphalt coating formed on one side of the encapsulated mat
generally comprises
a material having from about 0-30% mineral stabilizer, (i.e., powdered
limestone), about 5-
15% styrene-butadiene copolymer or styrene-butadiene-styrene copolymer, and
the balance
being flux asphalt having a Ring and Ball softening point of between about 80
F and about
150 F, (i.e., between about 26.67 C and about 65.56 C). Additionally, a
tackifying oil, such
as Hydrolene may be added. This second layer of material, being adhesive, is
used to adhere
the membrane to the roof deck.
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A release sheet, as described below, can be adhered to the adhesive material
to protect the
adhesive properties during transport and storage of the membrane.
FIG. 2 depicts a roofing membrane material 10 of the present invention. More
particularly, as
can be seen in FIG. 2, the roofing membrane material 10 comprises a
multilayered structure
formed of a fibrous mat 12, encapsulated entirely within a relatively non-
adhesive asphalt
composition 14, 16, to form an encapsulated mat 18, and an adhesive,
rubberized asphalt
layer 20 disposed on one surface of the encapsulated fibrous mat 18. An
acrylic coating 22 is
formed on the other surface of the encapsulated mat. Talc may be applied to
the acrylic
coating, or granular particles may be embedded therein, to further enhance
traction upon the
non-adhesive surface.
Optionally, a release sheet 24, such as a paper or plastic film 26 having a
siliconized surface
28 can be adhered to the relatively adhesive portion 20 of the membrane 10.
The release
sheet 24 is removed prior to use of the membrane material to allow the
adhesive portion 20 of
the membrane to be adhered to a roof surface. The release layer 24 is
typically a paper sheet
26 having a siliconized surface 28. As an alternative, the release layer can
comprise two
separate sheets; a first supporting sheet of a paper or polymeric film, and a
second sheet of a
low surface energy material. Additionally, in the case of a siliconized paper,
the silicon
coating may be replaced by some other suitable low surface energy material
such as a wax
emulsion or a soap solution.
As can also been seen in FIG. 2, the invention is characterized in that the
non-adhesive
asphalt 14, 16 infiltrates completely through the fibrous mat 12. In so doing,
the non-
adhesive material serves to seal the mat 12, without detracting from the mat's
particular non-
slip properties. As noted previously, and especially when formed from
fiberglass, a
polymeric coating may be applied to the mat to further seal it and to enhance
its non-slip
characteristics.
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CA 02308919 2000-05-19
The above-described structure addresses many of the needs currently embodied
in the roofing
industry. For example, the membrane provides a good seal between the decking
of the roof
surface and the roofing shingles to prevent moisture from penetrating into the
roof, even if ice
dams are formed on the eaves of the roof. The membrane also elongates and
recovers around
the nails, thereby providing an excellent seal around nails that pass through
the membrane to
secure shingles to the decking forming the roof surface. In addition, the
fibrous mat 12 serves
to provide a non-slip surface to the portion of the membrane material that
will be walked
upon by roofing installers. This non-slip surface offers the installers
greater traction, and
thus, greater safety, when installing the roof, even in wet or otherwise
slippery conditions.
Furthermore, the non-adhesive asphalt and acrylic layers do not stick to
shingles that are
layered above them, thereby allowing the shingles to be removed and replaced
without the
need to replace underlying roof decking.
Membranes of the present invention are made using a continuous, multi-coating
process. One
embodiment of the process is shown in FIG. 3. In FIG. 3, a web 40 of the
fibrous material is
passed through several coating stations. The first coating station 42
comprises an asphalt
supply pipe 44 which provides an excess of the non-adhesive asphalt material
46 to the upper
surface of the web. Excess non-adhesive asphalt material 46 flows over the web
and into a
first coating bath tank 48. A roller applicator 50 simultaneously applies the
non-adhesive
asphalt material 46 to the lower surface of the web 40. The coated web is then
scraped on its
upper surface by an upper doctor blade 52 and on its lower surface by a lower
doctor blade
54. The doctor blades serve to maintain the non-adhesive asphalt coating at a
predetermined
thickness.
Next, the web then passes below one or more acrylic spray heads 56, which
spray an aqueous
solution 58 of the acrylic coating onto the upper surface of the web. The
aqueous acrylic
solution is applied immediately after the web passes the first coating station
42. As such the
web is still hot, due to the coating of heated asphalt which has just been
applied. The heat of
the web (preferably about 175 C) causes the aqueous portion of the aqueous
acrylic solution
CA 02308919 2000-05-19
to evaporate, leaving behind the acrylic material. The heat of the web also
causes the acrylic
material to begin curing.
The web then passes to a second coating bath station 60. In the second coating
bath station
60, heated adhesive, rubberized asphalt material 62 is contained in a second
coating bath tank
64 and applied to the underside of the web 40 by a roller applicator 66. The
thickness of the
coating is controlled using a rolling, heated pipe positioned immediately
downstream of the
roller applicator 66.
As noted previously, an additional coating, such as talc or granular particles
may be applied
to the upper surface of the membrane. This coating serves to fill gaps where
the acrylic may
have not fully coated the asphalt surface. In so doing, the talc prevents the
membrane
material from sticking to itself when rolled. If desired, for example, talc
may be applied as
follows. A talc supply pipe 70 provides a mixture of talc/water mixture 72 to
the upper
surface of the web. This material combines with the partially cured acrylic
and fills any voids
that may be present in the acrylic coating. The talc mixture is metered on the
web surface
using a silicone-coated rubber roller 74 and one or more air blowers 78 that
force excess talc
mixture into a catch tray 76. The remaining talc/water mixture dries during
subsequent
manufacturing steps, leaving a coating of talc on the upper, acrylic surface
of the web 40.
Applying talc from a water mixture is advantageous in that the water portion
of the mixture is
a convenient, low cost carrier for the talc, which also serves to cool the
acrylic coating to
prevent it from sticking to the process machinery during manufacture. It is
additionally
advantageous since the web must be cooled prior to the application of the
release sheet (not
shown) to the lower surface of the web.
The release sheet can be applied by any of a wide variety of methods known to
those skilled
in the art of web handling and processing. It is noted that the present
invention is not
intended to be limited to the particular method described above. This method
has been
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described for illustration purposes, however, it should be understood that
many other methods
for forming the inventive membrane may be available to those of ordinary skill
in the art.
The resulting membrane product comprises a fibrous mat encapsulated within a
non-adhesive
asphalt material. The encapsulated mat will have an adhesive asphalt affixed
to its lower
surface, and an acrylic layer affixed to its upper surface. Talc or
particulate granules may
optionally be deposited on or in the acrvlic layer. To aid in shipping,
storing and handling the
membrane, a release sheet may be applied to the adhesive asphalt layer.
FIGS. 4 and 5 show the manner in which the membrane material 10 is intended
for use on a
roof deck 36 in the region of the roof eaves 38. In applying the present
invention, eaves
flashing is replaced by the membrane 10 described herein. In use, the release
sheet 24 is
removed from the lower surface of the double asphaltic layer 18, and the
membrane 10 is
secured to the roof deck 36 by adhesive action. The membrane 10 is positioned
along the
leading edge of the roof. Subsequently, a first row of shingles 37 is
positioned in an
overlying relationship to the membrane 10. The shingles are secured in place
using nails 39.
Although the roofing installer will often be caused to stand on the membrane
during
installation of the shingles, the fibrous mat of the inventive membrane 10
provides sufficient
friction to minimize the likelihood of slipping. Thus, as compared to many of
the known
roofing membranes, the membranes of the present invention provide a safer work
surface.
Equivalents
From the foregoing detailed description of the specific embodiments of the
invention, it
should be apparent that a unique roofing membrane material has been described.
Although
particular embodiments have been disclosed herein in detail, this has been
done by way of
example for purposes of illustration only, and is not intended to be limiting
with respect to the
scope of the appended claims which follow. In particular, it is contemplated
by the inventor
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that various substitutions, alterations, and modifications may be made to the
invention
without departing from the spirit and scope of the invention as defined by the
claims.
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