Note: Descriptions are shown in the official language in which they were submitted.
FIRE-RESISTANT MULTI-LAYER MEMBRANE
Field of the Invention
[0001] The invention pertains to multi-layer membranes, and in particular,
multi-layer
membranes with fire-resistant properties for use in various applications,
including for
example as roofing and flooring underlayments.
Background of the Invention
[0002] Multi-layer membranes are known in the art. One of the challenges
surrounding
the manufacture of multi-layer membranes is their stability upon exposure to
severe
weathering. For example, the layers within the membrane could delaminate from
each other
upon exposure to high temperatures. It is desirable for a multi-layer membrane
to maintain
stability under severe weathering. The present invention is directed to
improved multi-layer
membranes with fire-resistant properties.
Summary
[0003] One aspect of the invention provides a multi-layer membrane with
high thermal
stability, i.e., the membrane being capable of maintaining its structure when
exposed to
adverse weathering such as at temperatures of below -20 C and greater than
about 60 C
for periods of greater than 12 months. A multi-layer membrane with high
thermal stability
allows its layers to remain bonded with each other without delamination after
being exposed
to adverse weathering.
[0004] The multi-layer membrane has at least a polymeric layer
containing a water-
resistant coating bonded to a fire resistant component. The fire resistant
component has at
least a first fire resistant coating bonded to a carrier layer. The water
resistant polymeric
layer may be bonded to the first fire resistant coating or the carrier layer.
Some
embodiments of the invention include a second fire resistant coating bonded to
the carrier
layer on a surface opposite to the first resistant coating. An outer surface
of the water
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resistant polymeric layer which is arranged to be exposed to the environment
may be
mechanically and/or chemically modified to provide slip resistance. In some
embodiments,
a sacrificial anti-slip layer is arranged on the outer surface of the water
resistant polymeric
layer. In such embodiments, an outer surface of the anti-slip layer may be
mechanically
and/or chemically modified to provide slip resistance, while the outer surface
of the water
resistant polymeric layer remains smooth. The multi-layer membrane may be
applied on a
surface of a structural support member (e.g., a roof) by means of mechanical
fasteners, or
adhesive. In some embodiments, the multi-layer membrane further includes a
back bonding
layer bonded to the second fire resistant coating or the carrier layer to
provide self-adhesive
properties. In such embodiments, the back bonding layer is releasably attached
to a release
liner. Some embodiments of the invention include a support fabric bonded
between the
water resistant polymeric layer and the fire resistant component. A middle
bonding layer
may be bonded between the support fabric and the fire resistant component.
[0005] Further aspects of the invention and features of specific
embodiments of the
invention are described below.
Brief Description of the Drawings
[0006] Exemplary embodiments are illustrated in referenced figures of the
drawings. It
is intended that the embodiments and figures disclosed herein are to be
considered
illustrative rather than restrictive.
[0007] Figure 1 is a schematic diagram of a multi-layer membrane
according to a first
example embodiment.
[0008] Figure 2 is a schematic diagram of a multi-layer membrane
according to a
second example embodiment.
[0009] Figure 3 is a schematic diagram of a multi-layer membrane according
to a third
example embodiment.
[0010] Figure 4 is a schematic diagram of a multi-layer membrane
according to a fourth
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example embodiment.
[0011] Figure 5 is a schematic diagram of a multi-layer membrane
according to a fifth
example embodiment.
[0012] Figure 6 is a schematic diagram of a multi-layer membrane
according to a sixth
example embodiment.
[0013] Figure 7 is a schematic diagram of a multi-layer membrane
according to a
seventh example embodiment.
[0014] Figure 8 is schematic diagram of a multi-layer membrane according
to an eighth
example embodiment.
[0015] Figure 9 is schematic diagram of a multi-layer membrane according to
a ninth
example embodiment.
[0016] Figure 10 is schematic diagram of a multi-layer membrane
according to a tenth
example embodiment.
Detailed Description
[0017] The invention provides multi-layer membranes with fire resistant
properties. The
multi-layer membranes of this invention achieve a Class A rating when tested
according to
UL 790 and/or ASTM E-108 Standard Test Methods for Fire Tests of Roof
Coverings.
Referring to Figures 1 to 5, the multi-layer membrane 10 has a water resistant
polymeric
layer 12 positioned at a top layer arranged to be exposed to the environment
and a fire
resistant component 13 bonded to the water resistant polymeric layer 12. The
fire resistant
component 13 comprises a carrier layer 14 bonded to a first fire resistant
coating 16. In
some embodiments, the first fire resistant coating 16 is bonded between the
water resistant
polymeric layer 12 and the carrier layer 14 (as shown in Figure 1). In some
embodiments,
the carrier layer 14 is bonded between the water resistant polymeric layer 12
and the first
fire resistant coating 16 (as shown in Figure 2). The water resistant
polymeric layer 12 may
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comprise one or more thermoplastic components to form a water resistant
coating, and the
coating optionally further includes organic and/or inorganic fillers,
colorants, ultraviolet light
absorbers, dyes, pigments and other suitable additives. The thermoplastic
component may
be any suitable plastic polymer material including for example polyolefin such
as
polypropylene and polyethylene, polyolefin elastomers such as thermoplastic
elastomers
(TPE), ethylene vinyl acetate (EVA) polymers, and/or acrylic polymers such as
resins that
include methyl-acrylate. The weight of the water resistant polymeric layer 12
may be in the
range of from about 10 gsm to about 80 gsm. In an example embodiment, the
water
resistant polymeric layer 12 comprises about 50% to about 80% by weight of
polypropylene,
about 15% to about 30% by weight of low density polyethylene (LDPE), about
0.5% to
about 8% by weight of UV additives, and about 0.5% to about 12% by weight of
colorants.
[0018] An outer surface 18 of the water resistant polymeric layer 12 may
be chemically
and/or mechanically modified so as to provide slip resistance properties. For
example, the
outer surface 18 may be embossed with a texture. An embossed surface includes
a plurality
of depressed portions and elevated portions. The outer surface 18 may
alternatively be
coated with an anti-slip additive such as thermoplastic polyolefin (TPO),
thermoplastic
elastomers (TPE), ethylene-vinyl acetate (EVA), Reptyle FXTM, foaming agents,
calcium
carbonate (CaCO3), sand, and lace coating.
[0019] The carrier layer 14 may be made of any thermally resistant
materials, e.g.,
materials with low thermal diffusivity. Examples of materials with low thermal
diffusivity
include metal foil or film such as aluminum foil, woven (e.g., plain weave,
twill weave, or
satin weave) or non-woven fiberglass, polyvinyl chloride (PVC), silicone
rubber, felt (e.g.,
carbonized felt), polymeric fleece (e.g., polyethylene terephthalate (PET)
fleece), other non-
woven polymeric material including fabrics made by a needle-punch process, and
fire
retardant mats (e.g., an expandable graphite mat). The weight of the carrier
layer 14 may
be in the range of from about 100 gsm to about 1,000 gsm. In an example
embodiment, the
carrier layer 14 is made of woven fiberglass which contains 100% silicon
dioxide.
[0020] The first fire resistant coating 16 includes a first filler 24
mixed with a first carrier
26. In some embodiments, the fire resistant component 13 includes two layers
of fire
resistant coating, with the first fire resistant coating 16 and a second fire
resistant coating
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28 bonded to opposing surfaces of the carrier layer 14 as illustrated in
Figure 3. The second
fire resistant coating 28 has a second filler 30 mixed with a second carrier
32. The second
fire resistant coating 28 may have the same composition as or a different
composition from
the first fire resistant coating 16, i.e., the materials used for the first
and second fillers 24, 30
and/or the first and second carriers 26, 32 and the amounts contained therein
may be the
same or different. The first and second fire resistant coatings 16, 28 apply
onto opposing
surfaces of the carrier layer 14 to form three separate layers. The first and
second fire
resistant coatings 16, 28 may be applied onto opposing surfaces of the carrier
layer 14
when the coatings 16, 28 are in liquid or molten form. In some embodiments,
the carrier
layer 14 is free from any fire resistant coatings 16, 28, i.e., the carrier
layer 14 is not
impregnated with any fire resistant coatings 16, 28. In some embodiments, the
carrier layer
14 contains less than about 20% of fire resistant coatings 16,28 impregnated
therein.
[0021] The first and second fillers 24, 30 are made of substances that
have fire
resistant properties. In some embodiments, the first and second fillers 24, 30
are made of
an intumescent substance, such as expandable graphite, ammonium polyphosphate
(APP),
melamine (MEL), boric acid, bisphenol A (BPA) and polyamide amine, or
combinations
thereof. Intumescent substances expand when they are heated beyond an onset
temperature, thereby creating a foamed cellular charred layer on the surface.
This foamed
layer has low thermal diffusivity and therefore retards the spread of fire. In
some
embodiments, the onset temperature of the first and/or second filler 24, 30 is
at least 160 C,
in the range of from about 180 C to about 200 C.
[0022] The first and second fillers 24, 30 can, however, be any
inorganic and/or organic
fillers. Examples of suitable inorganic fillers include titania, clay, silica,
fumed silica, alumina
(A1203), aluminum trihydrate-ATH (Al (OH)3) and combinations thereof. Examples
of suitable
organic fillers include halogenated flame retardant, non-halogenated flame
retardant, other
olefinic fillers and combinations thereof.
[0023] Any materials suitable for binding the first and second fillers 24,
30 can be used
as the first and second carriers 26, 32. The first and second carriers 26, 32
may be an
organic or inorganic material. Examples of suitable materials for use as the
first and second
carriers 26, 32 include polyvinyl chloride (PVC), silicone, acrylic,
polyurethane, ethylene
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propylene diene monomer rubber (EPDM rubber), ethylene-vinyl acetate (EVA) or
epoxy
carriers or resins. In some embodiments, a filler content in the first and
second fire resistant
coatings 16, 28 is in the range of from about 20% to about 80% by weight, and
a carrier
content in the first and second fire resistant coatings 16, 28 is in the range
of from about
20% to about 80%. The weights of the first and second fire resistant coatings
16, 28 may be
in the range of from about 20 gsm to about 250 gsm. In an example embodiment,
the first
and second fire resistant coatings 16, 28 comprise 60% by weight of expandable
graphite
as the fillers 24, 30, and 40% by weight of an acrylic binder as the carriers
26, 32.
[0024] In some embodiments, the multi-layer membrane 10 further includes a
support
fabric 34 bonded between the water resistant polymeric layer 12 and the first
fire resistant
coating 16. The support fabric 34 may be bonded directly to the first fire
resistant coating
16, or may be bonded to the first fire resistant coating 16 by a middle
bonding layer 36, as
illustrated in Figure 4. In the latter embodiment, the support fabric 34
stabilizes the
adhesion of the water resistant polymeric layer 12 to the middle bonding layer
36,
facilitating a strong lamination between the water resistant polymeric layer
12 and the first
fire resistant coating 16, reducing the likelihood of delamination of the
water resistant
polymeric layer 12 from the first fire resistant coating 16.
[0025] The support fabric 34 can be any suitable materials that can provide
reinforcement to the membrane 10, such as a woven (e.g., plain weave, twill
weave, or
satin weave) or non-woven scrim or mat. Examples of suitable materials that
can be used to
form the support fabric 34 include fiberglass, polyolefin such as
polypropylene (PP) or
polyethylene (PE), and polyester such as polyethylene terephthalate (PET). The
weight of
the support fabric 34 may be in the range of from about 10 gsm to about 200
gsm. In an
example embodiment, the support fabric 34 is made of woven fiberglass which
contains
100% silicon dioxide. As another example, the support fabric 34 is a non-woven
scrim such
as a lay-up fabric.
[0026] Referring to Figures 6 to 10, the multi-layer membrane 10 optionally
includes a
sacrificial anti-slip layer 20 bonded to the outer surface 18 of the water
resistant polymeric
layer 12 such that the anti-slip layer 20 becomes the top layer that is
arranged to be
exposed to the environment. As used herein, a "sacrificial layer" means that
the layer can
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be removed or omitted without affecting the functionality of the membrane. The
anti-slip
layer 20 may include a non-woven polymeric layer, and optionally combined with
colorants,
ultraviolet light absorbers, dyes, pigments and other suitable additives such
as other anti-
slip additives (e.g., thermoplastic polyolefin (TPO), thermoplastic elastomers
(TPE),
ethylene-vinyl acetate (EVA), Reptyle FXTM, foaming agents, calcium carbonate
(CaCO3),
sand, and lace coating) and fire resistant additives. The non-woven polymeric
layer of the
anti-slip layer 20 can be any suitable polymer, including for example
polyolefin such as
polypropylene and polyethylene, polyolefin elastomers such as thermoplastic
elastomers
(TPE), and polyesters such as polyethylene terephthalate (PET). An outer
surface 22 of the
anti-slip layer 20 may be smooth, or may be chemically and/or mechanically
modified to
provide further slip resistance properties. In embodiments in which a multi-
layer membrane
10 includes the anti-slip layer 20, the outer surface 18 of the water
resistant polymeric layer
12 is not chemically and/or mechanically modified, i.e., the water resistant
polymeric layer
12 does not provide anti-slip resistance. The weight of the anti-slip layer 20
may be in the
range of from about 15 gsm to about 220 gsm. In an example embodiment, the
anti-slip
layer 20 comprises about 80% to about 99% by weight of polypropylene, about
0.5% to
about 8% by weight of UV additives, and about 0.5% to about 12% by weight of
colorants.
[0027] The multi-layer membrane 10 may be installed onto a surface of a
structural
support member (e.g., a roof) by mechanically attaching it to the surface by
means of for
example mechanical fasteners that penetrate the multi-layer membrane 10 to
engage the
structural support member. The multi-layer membrane 10 may alternatively be
attached to
the surface of the structural support member by means an adhesive. In such
embodiments,
as shown in Figures 5 and 10, the multi-layer membrane 10 further includes a
back bonding
layer 38 adhered to a surface 40 of the bottommost layer of the multi-layer
membrane 10
opposite to the water-resistant polymeric layer 12 or the anti-slip layer 20.
In some
embodiments (e.g., in the Figures 1 and 6 embodiments), the bottommost layer
of the multi-
layer membrane 10 is the carrier layer 14. In some embodiments (e.g., in the
Figures 2 and
7 embodiments), the bottommost layer of the multi-layer membrane 10 is the
first fire
resistant coating 16. In some embodiments (e.g., in the Figures 3, 4, 8 and 9
embodiments), the bottommost layer of the multi-layer membrane 10 is the
second fire
resistant coating 28.
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[0028] The middle and back bonding layers 36, 38 (if one or both are
present in the
multi-layer membrane 10) comprise an adhesive composition suitable for
securing the
support fabric 34 to the first fire resistant coating 16 and for securing the
second fire
resistant coating 28 to the structural support member respectively. In some
embodiments,
the middle and/or back bonding layers 36, 38 is made of a polymeric material
such as a
thermoset or a thermoplastic to form a pressure sensitive adhesive (i.e., an
adhesive that
forms a bond when pressure is applied to bond the adhesive with a surface) or
a
temperature sensitive adhesive (i.e., an adhesive which is activated by heat).
In some
embodiments, the middle and/or back bonding layer 36, 38 is made from butyl
rubber or
rubber modified asphalt (bitumen). In some embodiments, the middle bonding
layer 36 is
made from a polymeric bonding layer such as ethylene-vinyl acetate (EVA),
LotaderTM,
thermoplastic elastomers (TPE), and/or thermoplastic polyolefin (TPO). In some
embodiments, the middle and/or back bonding layers 36, 38 are free from
inorganic fillers.
The weight of the middle bonding layer 36 may be in the range of from about 20
gsm to
about 500 gsm. The weight of the back bonding layer 38 may be in the range of
from about
50 gsm to about 1,000 gsm. In an example embodiment, both the middle bonding
layer 36
and the back bonding layer 38 comprise a rubber-based hot-melt pressure
sensitive
adhesive. The middle and back bonding layers 36, 38 may comprise the same
adhesive
composition, or different adhesive compositions.
[0029] In some embodiments, one or both of the middle and/or back
bonding layers 36,
38 is free from rubber modified asphalt (bitumen). The presence of bitumen in
the multi-
layer membrane 10 can reduce the thermal stability of the overall membrane,
and
consequently lowering the shelf-life of the product.
[0030] A release liner 42 is releasably attached to the back bonding
layer 38 for
protecting the back bonding layer 38 until use. The release liner may be made
of paper,
polyolefins such as polypropylene (PP) or polyethylene (PE), or polyester such
as
polyethylene terephthalate (PET). One or both sides of the release liner may
be coated with
a release coating composition containing for example silicone.
[0031] Additional layers can be added to the multi-layer membrane 10 for
purposes
such as for providing further reinforcement. For example, an additional
support fabric can
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be included in the multi-layer membrane 10, bonded between the middle bonding
layer 36
and the first fire resistant coating 16. The additional support fabric
increases the lamination
strength between the water resistant polymeric layer 12 and the first fire
resistant coating
16, and/or provides an interface between the anti-slip layer 20 and the first
fire resistant
coating 16. The additional support fabric may be made of a non-woven or woven
polymeric
layer, film, foil, non-woven, or woven mat.
[0032] The multi-layer membrane 10 can be applied on a variety of
different surfaces
such as plywood, oriented strand board (OSB), polyvinyl chloride (PVC),
gypsum,
thermoplastic polyolefin (TPO), ethylene propylene diene monomer rubber (EPDM
rubber),
metal and concrete, which makes it useful for various applications, such as
flooring and
roofing underlayments.
[0033] The multi-layer membrane of this invention passes each of the
ASTM E 108 and
UL 790 Standard Test Methods for Fire Tests of Roof Coverings, as well as one
or more of
ASTM D 1970 (Standard Specification for Self-Adhering Polymer Modified
Bituminous
Sheet Materials Used as Steep Roofing Underlayment for Ice Dam Protection),
ICC ES AC
188 (Criteria for Roofing Underlayments), ICC ES AC 48 (Severe Climate), ASTM
D226
(Standard Specification for Asphalt-Saturated Organic Felt Used in Roofing and
Waterproofing), ASTM D4869 (Standard Specification for Asphalt-Saturated
Organic Felt
Underlayment Used in Steep Slope Roofing), CAN/CSA A123.3 (Asphalt saturated
organic
roofing felt), and TAS 103 (Test Procedure for Self-adhered Underlayments for
use in
Discontinuous Roof Systems).
[0034] The multi-layer membrane 10 has a total weight of greater than about
500 gsm,
and ranging from about 500 gsm to about 2,000 gsm, and a thickness of greater
than about
40 mils, and ranging from about 40 mils to about 70 mils. The membrane has a
wide
functional temperature range, extending from a low temperature at around -20 C
to a high
of about 139 C. The membrane maintains thermal stability at a maximum
temperature of
greater than 90 C, and ranging from about 90 C to 139 C. The tensile strength
of the
membrane may be greater than about 60 lb/in in the machine direction (MD) and
in the
cross-machine direction (CD), and ranging from about 60 lb/in to about 250
lb/in in the MD
and in the CD. The elongation strength of the membrane is greater than about
40% in the
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MD and in the CD, and ranging from about 40% to about 100% in the MD and in
the CD.
The bonding strength of the membrane is greater than about 40 pounds of the
back
bonding layer per feet of plywood surface (lbs/ft), at temperatures of 4 C and
23 C. The
shelf life of the membrane is greater than about 12 months, and ranging from
about 12
months to about 18 months. The above are results from tests conducted in
accordance with
ASTM D1970.
Example 1
[0035] A self-adhesive multi-layer membrane 10 with eight layers was
made. The
uppermost anti-slip layer 20 comprises 95% by weight of polypropylene, 3% by
weight of
UV additive, and 2% by weight of colorant, with a weight of 90 gsm. The water
resistant
polymeric layer 12 comprises 78% by weight of polypropylene, 20% by weight of
low
density polyethylene (LDPE), 2% UV additive, and 0% by weight of colorant,
with a weight
of 25 gsm. The middle bonding layer 36 is a rubber-based hot melt-pressure
sensitive
adhesive, with a weight of 200 gsm. The first and second fire resistant
coatings 16, 28
contain 60% by weight of expandable graphite as the first and second fillers
24, 30 and
40% by weight of a binder containing acrylic, each having a weight of 100 gsm.
The carrier
layer 14 is made of a woven fiberglass which contains 100% silicon dioxide,
with a weight of
630 gsm. The back bonding layer 38 is a rubber-based hot melt-pressure
sensitive
adhesive, with a weight of 460 gsm, and thickness of 12.5 mils. The release
liner 42 is a
double-sided polyethylene that is coated with silicone, with a weight of 50
gsm. The total
weight and thickness of the multi-layer membrane 10 is 1655 gsm and 75 mils
respectively.
[0036] This seven-layer membrane was tested to be in compliance with
each of the
following tests: ASTM E 108 UL 790, ASTM D 1970, ICC ES AC 188, ICC ES AC AC
48,
and TAS 103-95.
[0037] The following are results from tests that were conducted in
accordance with the
above listed standard tests. The seven-layer membrane is nail-sealable (i.e.,
the membrane
is capable of sealing around the nails) and has low water absorption (i.e.,
water absorbency
of less than about 0.1% when tested in accordance with ASTM D5147). The
membrane
was found to maintain thermal stability at a maximum of 75 C when tested
against ASTM
D1970. The tensile strength of the membrane is 148 lb/in in the machine
direction (MD) and
Date Recue/Date Received 2021-03-24
163 lb/in in the cross-machine direction (CD). The elongation strength of the
membrane is
106% in the MD and 84% in the CD. The bonding strength of the membrane is 8
pounds of
the back bonding layer per feet of plywood surface (lb/ft) at -20 C, 100.9
lb/ft at 4 C and
79.8 lb/ft at 23 C. The shelf life of the membrane is about 48 months and the
outdoor
exposure time is about 12 months.
Example 2
[0038] A self-adhesive multi-layer membrane 10 with nine layers of the
type depicted in
Figure 10 was made. The uppermost anti-slip layer 20 comprises 95% by weight
of
polypropylene, 3% by weight of UV additive, and 2% by weight of colorant, with
a weight of
90 gsm. The water resistant polymeric layer 12 comprises 78% by weight of
polypropylene,
19% by weight of low-density polyethylene (LDPE), 2% UV additive, and 1% by
weight of
colorant, with a weight of 25 gsm. The support fabric 34 and the carrier layer
14 are made
of a woven fiberglass which contains 100% silicon dioxide, having weights of
15 gsm and
630 gsm respectively. The first and second fire resistant coatings 16, 28
contain 60% by
weight of expandable graphite as the first and second fillers 24, 30 and 40%
by weight of a
binder containing acrylic, each having a weight of 100 gsm. The middle and
back bonding
layers 36, 38 are a rubber-based hot melt-pressure sensitive adhesive, having
weights of
200 gsm and 460 gsm, and thicknesses of 5 mils and 12.5 mils respectively. The
release
liner 42 is a double-sided polyethylene that is coated with silicone, with a
weight of 50 gsm.
[0039] Throughout the foregoing description and the drawings, in which
corresponding
and like parts are identified by the same reference characters, specific
details have been
set forth in order to provide a more thorough understanding to persons skilled
in the art.
However, well known elements may not have been shown or described in detail or
at all to
avoid unnecessarily obscuring the disclosure.
[0040] As will be apparent to those skilled in the art in the light of
the foregoing
disclosure, many alterations and modifications are possible in the practice of
this invention
without departing from the scope thereof. Accordingly, the description and
drawings are to
be regarded in an illustrative, rather than a restrictive, sense.
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