U.S. patent application number 13/379561 was filed with the patent office on 2012-04-26 for roofing underlayment.
This patent application is currently assigned to FIBERWEB, INC.. Invention is credited to Arthur H. Cashin, Brian Hickie.
Application Number | 20120096791 13/379561 |
Document ID | / |
Family ID | 42711763 |
Filed Date | 2012-04-26 |
United States Patent
Application |
20120096791 |
Kind Code |
A1 |
Cashin; Arthur H. ; et
al. |
April 26, 2012 |
Roofing Underlayment
Abstract
The present invention provides a composite sheet material (10)
that is particularly useful as an underlayment material in roofing
applications. In particular, the present invention provides a
composite sheet material (10) that is flexible, relatively
lightweight, resistant to water as well as being water vapor
permeable and resistant to tearing. In addition, the composite
sheet material (10) includes an outer non-skid surface (18) that
can help prevent slippage of workers during installation of the
roofing system. Embodiments of the composite sheet material can
help provide a roofing\structure, such as a shingled roof, with
fire resistance so that the roof can meet the Fire Resistance
requirements of ASTM E 108-07a, Class A.
Inventors: |
Cashin; Arthur H.;
(Nashville, TN) ; Hickie; Brian; (Hendersonville,
TN) |
Assignee: |
FIBERWEB, INC.
Old Hickory
TN
|
Family ID: |
42711763 |
Appl. No.: |
13/379561 |
Filed: |
July 2, 2010 |
PCT Filed: |
July 2, 2010 |
PCT NO: |
PCT/US10/40863 |
371 Date: |
December 20, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61222722 |
Jul 2, 2009 |
|
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|
Current U.S.
Class: |
52/309.1 ;
52/409; 52/745.06 |
Current CPC
Class: |
B32B 5/024 20130101;
B32B 2307/7145 20130101; B32B 2262/14 20130101; B32B 2307/54
20130101; B32B 2419/06 20130101; D06N 2209/123 20130101; B32B
2307/3065 20130101; D06N 5/00 20130101; E04D 12/002 20130101; D06N
2209/1671 20130101; B32B 2307/5825 20130101; B32B 2307/724
20130101; B32B 2307/7265 20130101; B32B 2307/546 20130101; B32B
27/20 20130101; B32B 5/08 20130101; B32B 27/12 20130101; B32B
2307/744 20130101; B32B 2270/00 20130101; B32B 2307/71 20130101;
B32B 2307/718 20130101; B32B 2262/0253 20130101; B32B 2264/10
20130101; B32B 2307/514 20130101; D06N 2209/1678 20130101; D06N
2209/128 20130101; B32B 27/32 20130101; B32B 27/34 20130101; D06N
2209/106 20130101; B32B 5/022 20130101; B32B 27/285 20130101; B32B
27/36 20130101 |
Class at
Publication: |
52/309.1 ;
52/745.06; 52/409 |
International
Class: |
E04D 5/10 20060101
E04D005/10; E04D 5/06 20060101 E04D005/06; E04D 5/08 20060101
E04D005/08 |
Claims
1. A method of installing a roof system on a building comprising
covering an exterior surface of a roof structure with a breathable,
composite sheet material having water barrier and fire resistant
properties, the composite sheet material including a woven or
nonwoven substrate defining an upper surface of the sheet material,
and an extrusion coated film layer covering an opposite surface of
the nonwoven substrate and defining a lower surface of the sheet
material, wherein the film layer has a moisture vapor transmission
rate of at least 35 g/m.sup.2/24 hr. at 50% relative humidity and
23.degree. C., and a hydrostatic heads of at least 55 cm; and
positioning the composite sheet material onto the roof structure so
that that the film layer faces towards the roof structure and the
nonwoven substrate faces outwardly to provide a non-skid
surface.
2. The method of claim 1, wherein the film layer comprises a
polyolefin polymer and at least 40% by weight inorganic filler.
3. The method of claim 1, wherein said film layer comprises at
least 40% by weight inorganic filler, and sheet material has been
subjected to stretching in both the CD and the MD by incremental
stretching to impart to the composite fabric a moisture vapor
transmission rate (MVTR) of at least 100 g/m.sup.2/24 hr. at 50%
relative humidity and 23.degree. C.
4. The method of claim 1, wherein the film layer has a basis weight
that is from about 70 to 100 g/m.sup.2.
5. The method of claim 1, wherein the film layer has a basis weight
that is at least about 80 g/m.sup.2.
6. The method of claim 1, wherein the non-skid surface of the
composite sheet material has a coefficient of friction that is at
least 0.70.
7. The method of claim 1, wherein the non-skid surface of the
composite sheet material has a coefficient of friction that is from
about 0.73 to 0.88.
8. The method of claim 1, wherein the film layer is a monolithic
film comprising a blend of polypropylene and from about 20 to 30%
by weight of a co-polyether amide, a block co-polyether ester, or a
combination thereof.
9. The method of claim 1, further comprising the step of attaching
a plurality of shingles to the composite sheet material.
10. The method of claim 9, wherein the roof system comprising the
composite sheet material meets the requirements of ASTM E 108 Class
A Fire Resistant Test.
11. The method of claim 1, wherein the nonwoven substrate is a
spunbond nonwoven fabric comprising polypropylene continuous
filaments.
12. A composite sheet material useful as a waterproof underlayment
for a roof of a structure, the sheet material comprising a woven or
nonwoven substrate and a film layer covering a surface of the
nonwoven substrate, the film layer comprising a polyolefin polymer
and at least 40% by weight inorganic filler, and wherein the
composite sheet material has a moisture vapor transmission rate
(MVTR) of at least 34 g/m.sup.2/24 hr. at 50% relative humidity and
23.degree. C., and a hydrostatic heads of at least 55 cm, and
wherein the film layer has a basis weight of at least 80
g/m.sup.2.
13. The sheet material of claim 12, wherein the s sheet material
has been subjected to stretching in both the CD and the MD.
14. The sheet material of claim 13, wherein the film layer is
extrusion coated onto the substrate and wherein composite sheet
material has been incrementally stretched to render the composite
sheet material breathable.
15. The sheet material of claim 12, wherein a roof system
comprising a roof deck, a plurality of covering shingles and the
composite sheet material as an underlayment material disposed
between the roof deck and shingles meets the requirements of ASTM E
108 Class A Fire Resistant Test.
16. The sheet material of claim 12, wherein the substrate includes
an exposed non-skid surface having a coefficient of friction that
is from 0.70 to about 0.90.
17. The sheet material of claim 12, wherein the substrate includes
an exposed non-skid surface having a coefficient of friction that
is from about 0.73 to 0.88.
18. The sheet material of claim 12, wherein the film layer includes
a UV stabilizer, a thermal stabilizer, or a combination
thereof.
19. A roofing system comprising: a) a roof deck of a building; b)
an underlayment material attached to said roof deck, wherein the
underlayment material comprises a composite sheet material having
water barrier and fire resistant properties, the composite sheet
material including a nonwoven substrate defining an upper surface
of the sheet material, and an extrusion coated film layer covering
an opposite surface of the nonwoven substrate and defining a lower
surface of the sheet material that faces towards the roof deck,
wherein the film layer has a moisture vapor transmission rate of at
least 35 g/m.sup.2/24 hr. at 50% relative humidity and 23.degree.
C., and a hydrostatic heads of at least 55 cm; and c) a
multiplicity of courses of roofing shingles attached to said
underlayment material, and wherein the roof system meets the
requirements of ASTM E 108 Class A Fire Resistant Test.
20. The roofing system of claim 19, wherein said film layer
comprises at least 40% by weight inorganic filler, and sheet
material has been subjected to stretching in both the CD and the MD
by incremental stretching to impart to the composite fabric a
moisture vapor transmission rate (MVTR) of at least 100
g/m.sup.2/24 hr. at 50% relative humidity and 23.degree. C. and a
hydrostatic head of at least 55 cm.
21. The roofing system of claim 19, wherein the film layer has a
basis weight that is from about 70 to 100 g/m.sup.2.
22. The roofing system of claim 19, wherein the film layer has a
basis weight that is at least about 80 g/m.sup.2.
23. The roofing system of claim 19, wherein the non-skid surface of
the composite sheet material has a coefficient of friction that is
at least 0.70.
24. The roofing system of claim 19, wherein the non-skid surface of
the composite sheet material has a coefficient of friction that is
from about 0.73 to 0.88.
25. The roofing system of claim 19, wherein the film layer is a
monolithic film comprising a blend of polypropylene and from about
20 to 30% by weight of a co-polyether amide, a block co-polyether
ester, or a combination thereof.
26. A roofing system comprising: a) a roof deck of a building; b)
an underlayment material attached to said roof deck, wherein the
underlayment material comprises a composite sheet material having
water barrier and fire resistant properties, the composite sheet
material including a woven or nonwoven substrate and a film layer
covering a surface of the substrate, the film having a basis weight
of at least 70 g/m.sup.2 and a moisture vapor transmission rate of
at least 35 g/m.sup.2/24 hr. at 50% relative humidity and
23.degree. C., and a hydrostatic heads of at least 55 cm; and c) a
multiplicity of courses of roofing shingles attached to said
underlayment material, and wherein the roof system meets the
requirements of ASTM E 108 Class A Fire Resistant Test.
27. The roofing system of claim 26, wherein the substrate layer
faces in the direction of the roof deck.
28. The roofing system of claim 26, wherein the film layer faces in
the direction of the roof deck.
29. The roofing system of claim 26, wherein the substrate layer
comprises a woven slit film.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to composite sheet materials
for use as an underlayment material in roofing applications.
BACKGROUND OF THE INVENTION
[0002] Roofing underlayment materials are used in a wide variety of
roofing applications. Roofing underlayment was originally used as a
temporary protection against the elements during construction, but
is now an integral part of a home's overall roof system. Roofing
underlayment is typically used under asphaltic shingles, shakes,
tile, cedar, metal, and various other roofing panels to provide a
second layer of protection on top of the sheathing to help keep
moisture out of the interior of the building. Roofing underlayment
materials can also be used to provide fire resistance, wind uplift
resistance, puncture resistance, and resistance to wind-driven
rain. In addition to providing the above properties, it may also be
desirable for the roof underlayment material to be breathable to
allow for trapped moisture vapor to pass through from the interior
of the building.
[0003] One of the earliest and most widely used types of roofing
underlayment materials is asphalt-saturated felt, also commonly
known as builder's felt or felt paper. Asphalt-saturated felt has
been used as a roofing underlayment material for more than 50
years. The felt is made from a paper base that is impregnated or
saturated with asphalt to make it more resistant to the elements.
Some papers are actually coated in asphalt, while others are truly
saturated. Felt paper is generally installed by being rolled across
a roof deck and is then stapled or nailed in place. Shingles are
then installed over the top of the previously installed felt paper.
Although inexpensive and fairly easy to install, felt paper can be
susceptible to tearing, especially in hot temperatures, and makes
for a slippery surface to walk on while installing the roof
covering. Asphalt felt also tends have poor breathability which can
result in moisture vapor being trapped within the roofing
system.
[0004] Recently, synthetic roofing underlayment materials have been
introduced into the market and are gaining acceptance in the
roofing industry. Synthetic roofing underlayments are based on
polymeric materials, such as polyethylene and polypropylene.
Synthetic roofing underlayments are generally more durable than
asphalt-saturated felt, waterproof, and breathable.
[0005] Although having many advantages over felt paper, many
synthetic roofing underlayment materials still have some
disadvantages.
[0006] In US patent application US2010/0056004A1 non-skid
properties of a roof underlayment are provided via the coefficient
of friction of a coating. The application discloses a
skid-resistant roof underlayment comprising a spunbond nonwoven web
and a coating on at least one surface having a coefficient of
friction of at least 0.40.
[0007] Thus, there still exists a need for roof underlayment
materials that are easy to install and have non skid properties and
help fire resistance to the roof system.
BRIEF SUMMARY OF THE INVENTION
[0008] The present invention provides a method of installing a roof
system comprising covering an exterior surface of a roof structure
with composite sheet material, the composite sheet material
comprising a substrate forming at least a part of a first surface
at the exterior of the composite sheet material and a film layer
forming at least a part of a second surface at the exterior of the
composite sheet material opposite to the first surface. The film
layer is arranged to control the breathability of the composite
sheet material. The method further comprises positioning the
composite sheet material onto the roof structure so that the second
surface faces towards the roof structure and the first surface
provides a non-skid surface.
[0009] By the application of this method, there is a reduced risk
of slipping while the sheet material provides a non-skid surface.
At the same time, in a simple embodiment the material used is a
composite of only two layers (the substrate and the film). As the
film faces the roof structure, it is not necessary to impart
non-skid properties to the film, which can thereby be optimized for
the breathability without being effected by measures to give it
non-skid properties. As only two layers are needed to provide
non-skip properties and the breathability, the composite sheet
material has a relatively lighter weight than other underlayment
material (e.g. having multiple fabric and/or film layers). As a
consequence the method is relatively easy and more roof can be
covered per roll and for instance less rolls need to be carried to
the roof. In embodiments the film layer is also used to optimize
for instance the water barrier properties and/or to influence the
flame retardant properties of roofs in which the composite sheet
material is used.
[0010] According to an aspect of the invention a composite sheet
material for use as a roof underlayment is provided, wherein the
composite sheet material comprises a substrate forming at least an
exposed part of a first surface at the exterior of the composite
sheet material and a film layer forming at least a part of a second
surface at the exterior of the composite sheet material opposite to
the first surface wherein the exposed part of the first surface
provides a non-skid surface. Furthermore the wherein the film layer
has a basis weight of at least 50 g/m.sup.2, 70 g/m.sup.2 or 75
g/m.sup.2.
[0011] The invention therefore provides a composite sheet material
that needs only two layers wherein the substrate provides non-skid
properties. The film is optimized for breathability without being
effected by measures to give it non-skid properties. As only two
layers are needed to provide non-skip properties and the
breathability, the composite sheet material has a relatively
lighter weight than other underlayment material (e.g. having
multiple fabric and/or film layers). As a consequence more roof can
be covered per roll of equal weight as roll of roof underlayment
with higher basic weights and for instance less rolls need to be
carried to the roof. In embodiments the film layer is also used to
optimize for instance the water barrier properties. The high basis
weight of the film gives the composite sheet material flame
retardant properties when used in a roof.
[0012] Advantageously, embodiments of the composite sheet material
provided excellent barrier, strength and anti skid properties
without the need for additional layers, such as additional
reinforcing mesh or scrim layers, multiple film barrier layers, or
additional coating or gritty materials for improving the non-skid
properties of the outer substrate layer.
[0013] The invention also provides a construction material
comprising a composite sheet material and a roof deck, wherein the
composite sheet material is attached to the roof deck with the
second surface facing the roof deck. The invention also provides a
roof comprising such a construction material an a multiplicity of
courses of roofing shingles attached to the construction material.
Furthermore a structure is provided by the invention, the structure
comprising such a roof.
[0014] The roof deck according to this invention uses the
advantages of the composite sheet material as described above. Note
that the roof deck can be pre-fabricated.
[0015] Furthermore the invention provides for a use of a composite
sheet material as a roof underlayment, the composite sheet material
comprising a substrate forming at least a part of a first surface
at the exterior of the composite sheet material and a film layer
forming at least a part of a second surface at the exterior of the
composite sheet material opposite to the first surface wherein the
first surface provides a non-skid surface.
[0016] This aspect of the invention relates to the use of the
composite sheet material above, so as to be able to profit from the
advantages of the composite sheet material.
[0017] Finally, the invention provides for a method of producing a
roofing underlayment material by coating a film onto a substrate
comprising arranging that the substrate forms at least a part of a
first surface at the exterior of the composite sheet material. The
method further comprises arranging that the part of the first
surface has a coefficient of friction with a minimum value of 0.50,
0.70, 0.73 or 0.80 as measured in accordance with ASTM F-1679 under
dry conditions.
[0018] This aspect of the invention relates to the production of
the composite sheet material according to an earlier aspect of the
invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0019] Having thus described the invention in general terms,
reference will now be made to the accompanying drawings, which are
not necessarily drawn to scale, and wherein:
[0020] FIG. 1 is a schematic cross sectional view of the composite
sheet material of the present invention;
[0021] FIG. 2 is a schematic diagram showing equipment suitable for
producing the composite sheet material of the present invention;
and
[0022] FIG. 3 is a view of a roofing system that includes the
composite sheet material of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The present invention now will be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all embodiments of the inventions are shown. Indeed,
these inventions may be embodied in many different forms and should
not be construed as limited to the embodiments set forth herein;
rather, these embodiments are provided so that this disclosure will
satisfy applicable legal requirements. Like numbers refer to like
elements throughout.
[0024] The present invention is directed to a roofing underlayment
material for use in roofing systems that comprises a composite
sheet material that is flexible, relatively lightweight, resistant
to water as well as being water vapor permeable and resistant to
tearing. The inventors has realized that a synthetic roofing
underlayment can give water barrier properties, breathability, good
tensile and tear strength, excellent resistance to UV light,
resistance to algae, fungi and mold, resistance to rot and decay,
etc. The underlayment material helps to protect the interior of the
building including the insulating materials underneath against
moisture, dust, blowing snow, wind, and the like. In particular,
the underlayment material provides a breathable membrane that
permits moisture vapor to escape through the roofing system while
being a barrier to water so that penetration of water into the
building is prevented.
[0025] In addition to the aforementioned desirable properties,
underlayment materials in accordance with embodiments of the
present invention can also help provide a roofing structure, such
as a shingled roof, with fire resistance so that the roof can meet
the Fire Resistance requirements of ASTM E 108-07a, Class A. Under
ASTM E 108-07a, the fire resistance characteristics of a roofing
covering are evaluated under a simulated fire originating outside
the building. Class A tests are applicable to roof coverings that
are effective against severe test exposure, afford a severe degree
of fire protection to the roof deck, do not slip from position, and
do not present a flying brand hazard. To meet the requirements of
Test A, a roofing system incorporating the composite sheet material
as an underlayment must past a Burning Brand test, Spread of Flame
Test, and an Intermittent Flame test.
[0026] In an embodiment (illustrated in FIG. 1) an underlayment
material based on a composite sheet material (10) includes a
(nonwoven or woven) fibrous substrate (12) and a film layer (14)
extending uninterruptedly and continuously over one surface of the
nonwoven fibrous substrate (22). Examples of woven substrates
include woven fabrics as well as woven slit films. The film layer
can be attached to the substrate layer in a variety of ways
including extrusion, lamination, roller application, doctor blades,
spray coatings, and the like. In a preferred embodiment, the film
is extruded directly onto the surface of the substrate.
[0027] In the embodiment, the film layer is extrusion coated
directly onto a surface of the substrate so that the film layer
(14) has a strong adherence to the substrate (12). As a result, the
film layer and the substrate are not subject to delamination but
instead are structurally combined with one another to form a
composite material. The peel adhesion of the film layer (14) to the
substrate (12) is at least 59 g/cm (150 grams/inch). High peel
adhesions are preferred as when the substrate and film layer
delaminate, it is more difficult to walk on the composite sheet
material which may be dangerous when the composite sheet material
is placed on a roof. In an embodiment the peel adhesion is 78 g/cm
(200 grams/inch). Most desirably, the adhesion is so great that the
fibers of the substrate will tear or break before delamination will
occur. This condition, known as "fiber tear," occurs above about 98
g/cm (250 grams/inch). Adhesion of the film to the substrate is
measured in accordance with the test procedure described below
under the section entitled "Test Methods."
[0028] Generally speaking, the breathability of the composite sheet
material may be controlled as desired for the intended application
of the materials. In barrier applications, it is generally
desirable that the composite sheet material has a moisture vapor
transmission rate (MVTR) that is at least 35 g/m.sup.2/day at 50%
relative humidity and 23.degree. C. (73.degree. F.) (e.g., perm of
5 or greater), and more desirably an MVTR of at least 50. In one
embodiment, the composite sheet material has a MVTR that is at
least 100 g/m.sup.2/day. In some embodiments, the composite sheet
material may have a MVTR of greater than about 150 g/m.sup.2/day,
more specifically greater than about 300 g/m.sup.2/day, and even
more specifically greater than about 500 g/m.sup.2/day. Typically,
underlayment applications do not require high moisture vapor
transmission rates and will often have a moisture vapor
transmission rate of less than about 2000 g/m.sup.2/day. It should
be understood however that materials having higher moisture vapor
transmission rates are equally within the scope of the invention.
In barrier applications it may also be desirable for the composite
sheet material to be impermeable to air flow. Preferably, the
composite sheet material has an Air Leakage Rate less than 0.02
L/(sm.sup.2), and more desirably less than 0.015 L/(sm.sup.2).
Moisture vapor transmission and Air Leakage rates are measured in
accordance with the test procedures described below under the
section entitled "Test Methods."
[0029] The substrate functions to support and carry the film layer
as well as to provide strength to the overall composite sheet
material. In a preferred embodiment the substrate is a nonwoven
substrate comprised of a plurality of polymeric fibers or filaments
that are randomly dispersed and bonded to one another at points of
intersection to form a nonwoven web having excellent strength.
Suitable polymeric materials for the nonwoven substrate may include
polyolefins, polyamides, polyesters, polyacrylates, or other
fiber-forming polymers. In a preferred embodiment, the nonwoven
substrate comprises randomly-laid spunbonded fibers, for example a
spunbonded polyolefin such as polyethylene, polypropylene, or
combinations thereof. Suitable spunbonded nonwovens may have a
basis weight equal to or greater than about 0.3 oz/yd.sup.2. As
discussed in greater detail below, a particularly preferred
nonwoven substrate comprises a spunbonded polypropylene having a
basis weight equal to or greater than about 1 oz/yd.sup.2, and more
specifically, a spunbonded polypropylene having a basis weight of
equal to or greater than about 1.5 oz/yd.sup.2. Spunbonded nonwoven
fabrics suitable for use in the composite sheet material have fiber
deniers in the range of 4 to 20.5, more specifically from about 7
to about 12, with spunbonded fabrics having fiber deniers at the
higher end of this range being preferred. The denier for example is
4.0, 7.7, 10 or 20.
[0030] Preferably, the substrate 12 is a high tenacity nonwoven
fabric formed from polymeric fibers which are randomly disposed and
bonded to one another to form a strong nonwoven web. It is
important for the substrate to have high tenacity and relatively
low elongation in order to provide the strength and other physical
properties required for a barrier material such as a roof
underlayment. Preferably, the substrate 12 has a grab tensile
strength of at least 133 Newtons (30 pounds), and more preferably
at least 178 Newtons (40 pounds) in at least one of the machine
direction (MD) or the cross-machine direction (CD). More
preferably, the substrate has a grab tensile strength of at least
267 N (60 pounds) in at least one of the MD and the CD. In one
embodiment, the substrate 12 has a grab tensile strength of at
least 165 Newtons (37 pounds) in the CD.
[0031] In addition to the high strength properties mentioned above,
it is desirable for the surface of the substrate to have non-skid
properties. Preferably, the surface of the substrate has a
coefficient of friction that is from about 0.50 to 1.0 and more
desirably from at least 0.70, and most desirably at least 0.80 as
measured in accordance with ASTM F-1679. In one embodiment, the
coefficient of friction for the surface of the substrate ranges
from 0.70 to about 0.90, and in particular, from about 0.73 to
0.88. Advantageously, the non-skid surface of the composite sheet
material can be provided in the absence of using additional
coatings or gritty materials as is common in other underlayment
materials.
[0032] In some embodiments, it may also be desirable for the
substrate to have a Martindale Abrasion this is between 0.2 and
0.4, and in particular, from about 0.2 to 0.35, and more
particularly, from about 0.25 to 0.3. The Martindale Abrasion
rating of the substrate is indicative of how much fiber, as a
percentage, is rubbed or abraded off of the fabric after a set
number of cycles. If the number is low (e.g., less than 0.4), the
fibers tend to be more locked down into the substrate and generally
resist rolling or pilling up. In the present invention, it is
believed that the relatively low Martindale Abrasion rating and the
high coefficient of friction, provides a composite sheet material
in which the fibers of the substrate are adhered tighter to the
surface of the substrate so as to provide a better traction
surface, and because the fibers resisting rolling or pilling, the
surface retains its integrity and non-skid properties, even after
repeatedly being walked on. Martindale Abrasion is determined in
accordance with INDA standard WSP-20.5 (40 cycles).
[0033] As shown in FIG. 1, the substrate 12 includes surface 18
that defines an outer surface of the composite sheet material, and
hence, an outer surface of the underlayment material. Surface 18
provides a substantially non-skid surface such that the composite
sheet material is particularly useful in roofing applications where
slippage by workers installing shingles or other roofing materials
can be a concern. In particular, the composite sheet material of
the present invention can be utilized as an underlayment material
in which the sheet material is positioned so that the film layer
faces towards the roof structure (i.e., roof deck) and the
substrate faces outwardly to provide a non-skid surface. In this
way, workers installing a roof are able to work on the surface of
the composite sheet material while the possibility of slipping is
minimized in contrast to some other forms of underlayment
materials. Additionally, the high strength properties of the
substrate helps prevent tearing or ripping of the sheet material
during roof installation.
[0034] One specific example of a commercially available nonwoven
fabric possessing the required high levels of strength is a product
sold under the trademark TYPAR.RTM. or TELKTON.RTM. by Fiberweb,
Inc. This product is a spunbonded nonwoven fabric made from fibers
in the form of substantially continuous filaments of polypropylene.
The filaments are mechanically cold-drawn and have a denier per
filament of from 4 to 20. They preferably exhibit a fiber
birefringence of at least 0.022. The fabric is area bonded, with
the filaments being bonded to one another at their crossover points
to form a nonwoven sheet material having excellent strength
characteristics. The spunbonded nonwoven substrate preferably has a
grab tensile strength in the machine direction (MD) of at least 267
N (60 lbs.) and in the cross machine direction (CD) of at least 178
N (40 lbs.). The nonwoven substrate is manufactured generally in
accordance with Kinney U.S. Pat. No. 3,338,992, using mechanical
draw rolls as indicated in FIG. 16. An example of another suitable
spunbonded nonwoven fabric is a product sold by Fiberweb, Inc.
under the trademark REEMAY.RTM.. This spunbonded nonwoven fabric is
formed of filaments of polyester.
[0035] Other examples of nonwoven substrates that may be used in
some embodiments of the invention include flash spun nonwoven
materials such as a flash spun high density polyethylene nonwoven
material commercially available from DuPont de Nemours Co. under
the trade name TYVEK.RTM.. The flash spun nonwoven materials are
available in a range of basis weights and are suitable for use in
the breathable materials of the invention. In certain embodiments,
the flash spun nonwoven materials will have a basis weight in a
range of from about 0.7 to about 4 oz/yd.sup.2.
[0036] In one embodiment, the required high tenacity and low
elongation of the nonwoven substrate are achieved by selection of a
manufacturing process in which the polymer fibers of the nonwoven
fabric are drawn to achieve a high degree of molecular orientation,
which increases fiber tenacity and lowers fiber elongation.
Preferably, the manufacturing process involves mechanically drawing
the fibers by means of draw rolls, as distinguished from other
well-known manufacturing processes for nonwovens which utilize
pneumatic jets or slot-draw attenuators for attenuating the freshly
extruded fibers. Pneumatic attenuation of the fibers via jets or
attenuators can not achieve the high spinline stress required for
orienting the polymer molecules to a high degree to develop the
full tensile strength capability of the fibers. Mechanically
drawing the fibers, on the other hand, allows for higher stresses
in the fiber to orient the polymer molecules in the fibers and
thereby strengthen the fibers. The drawing is carried out below the
melting temperature of the polymer, after the polymer has cooled
and solidified. This type of drawing process is conventionally
referred to as "cold-drawing" and the thus-produced fibers may be
referred to as "cold-drawn" fibers. Because the fibers are drawn at
a temperature well below the temperature at which the polymer
solidifies, the mobility of the oriented polymer molecules is
reduced so that the oriented polymer molecules of the fiber cannot
relax, but instead retain a high degree of molecular orientation.
The degree of molecular orientation of the fiber can be determined
by measuring the birefringence of the fiber. Cold-drawn fibers of
the type used in the present invention are characterized by having
a higher birefringence than fibers attenuated by pneumatic jets or
slot-draw attenuators. Consequently, the individual fiber tenacity
of a cold-drawn fiber is significantly greater than that of a fiber
which is attenuated or stretched by pneumatic jets or attenuators
of the type used in some spunbond nonwoven manufacturing
processes.
[0037] Cold-drawing of a fiber-forming polymer is characterized by
a phenomenon known as "necking down". When the undrawn fiber is
stretched, a reduction in diameter occurs in the fiber at a
discrete location, i.e. "neck" instead of a gradual reduction in
diameter. The morphology of a fiber drawn by cold-drawing is
different from the morphology of a fiber which has been attenuated
or stretched while still in the molten state where the polymer
molecules are mobile. The differences are evident from the x-ray
diffraction patterns, from birefringence measurements, and from
other analytical measurements.
[0038] Also contributing to the required high strength and low
elongation of the substrate is the method or mechanism by which the
fibers are bonded. Preferably, the nonwoven substrate is "area
bonded" as distinguished from a "point bonded" or "patterned
bonded" sheet material. In a point bonded or pattern bonded fabric,
discrete bond points or zones are separated from one another by
unbonded areas or zones. This type of bonding is often utilized for
applications in which it is desired to preserve the softness of the
fabric, such as nonwoven fabrics for diapers or hygiene products
for example. In an "area bonded" fabric, the fiber bonds are not
separated by unbonded areas, but instead are found throughout the
area of the fabric. Because of the larger number of fiber-to-fiber
bonds, area bonded fabrics are typically stronger than a point
bonded fabric and are also less soft and less flexible. The fibers
are adhered or bonded to one another throughout the fabric at
numerous locations where the randomly deposited fibers overlie or
cross one another.
[0039] The thermoplastic polymer fibers or filaments of the
nonwoven substrate 12 preferably contain pigments as well as
chemical stabilizers or additives for retarding oxidation and
ultraviolet degradation, and for imparting other desired properties
such as antimicrobial, antimold, or antifungal. Typically, the
stabilizers and additives are incorporated in the polymer at
conventional levels, e.g., on the order of about 0.5 to 2% by
weight. Typical stabilizers may include primary antioxidants
(including hindered amine-light stabilizers and phenolic
stabilizers), secondary antioxidants (such as phosphates), and
ultraviolet absorbers (such as benzophenones). The polymer
composition also preferably contains a pigment to render the
nonwoven fabric opaque. In one preferred embodiment, the fibers are
pigmented black using a black pigment, such as carbon black. If a
white color is desired, titanium dioxide pigment can be used at
comparable levels, or blends of titanium dioxide, with carbon black
or with other colored pigments could be employed. The fibers or
filaments are preferably circular in cross-section, although other
cross-sectional configurations such as trilobal or multilobal
cross-sections can be employed if desired.
[0040] The substrate 12 typically has a basis weight of at least 50
g/m.sup.2, preferably from 60 to 140 g/m.sup.2, and for certain
preferred embodiments, a basis weight of from 80 to 110
g/m.sup.2.
[0041] The film layer 14 comprises a polymeric material having
water barrier properties and that is inherently or that can be
rendered breathable to moisture vapor. The influence of the
substrate on the moisture vapor transmission rate is negligible
compared to that of the film. In an embodiment the film layer, and
hence the composite sheet material has a moisture vapor
transmission rate with a value of at least 35. In further
embodiments, the value is from about 50 to 110 g/m.sup.2/24 hr. 50%
relative humidity and 23.degree. C. The film layer also has a
hydrostatic pressure of at least 55 cm, or at least 100 cm. In
further embodiments the film layer has a hydrostatic pressure from
about 500 to 900 cm.
[0042] In one embodiment, the film layer comprises a polymeric
composition that is rendered microporous so that a desired moisture
vapor transmission rate can be achieved. As discussed in greater
detail below, the composition from which the film layer 14 is
formed may be prepared by blending or compounding one or more
thermoplastic polymers with suitable inorganic pore-forming fillers
and with suitable additives, stabilizers and antioxidants.
[0043] Suitable polymers for the polymer composition of the coating
include any thermoplastic polymers or blends of such polymers which
may be extruded directly onto the nonwoven substrate as a film such
that the film and the nonwoven substrate are structurally combined
with each other. Such polymers include, but are not limited to,
polyolefins, polyesters, polyamides, thermoplastic polyurethanes,
polyvinyl chloride, polystyrene, and copolymers of these polymers.
In a preferred embodiment, the polymer composition includes at
least one polyolefin polymer component, such as polypropylene,
propylene copolymers, homopolymers or copolymers of ethylene, or
blends of these polyolefins. The polymer composition may, for
example, comprise 100% polypropylene homopolymer, or blends of
polypropylene and polyethylene. Suitable polyethylenes include
linear low density polyethylene (LLDPE). The polymer composition
may also include minor proportions of other nonolefin polymers.
[0044] Suitable fillers for use in the respective film coatings
include, but are not limited to, various organic and/or inorganic
materials. In a specific embodiment, the filler may comprise one or
more finely powdered inorganic materials such as metal oxides,
metal hydroxides, metal carbonates and the like. Preferred fillers
include, but are not limited to, calcium carbonate, clay, silica,
kaolin, titanium dioxide, diatomaceous earth, or combinations of
these materials. Calcium carbonate is particularly preferred as a
pore-forming filler.
[0045] The particle size of the filler may be selected in order to
influence the micropore size in the coating and consequently the
breathability of the material product. Preferably, the pore-forming
filler has a particle size of no more than about 5 microns, and in
particular, the filler typically has an average particle size of
from about 0.5 to about 5 microns. The filler may optionally
include a surface coating to facilitate dispersion of the filler in
the polymer composition, to increase the ability of the filler to
repel water, and/or to increase incompatibility of the filler with
the polymer composition and the formation of micropores at the
vicinity of the filler. Suitable surface coatings include but are
not limited to organic acids such as stearic or behenic acid, salts
of organic acids such as calcium stearate, fatty acids and salts
thereof, nonionic surfactants, and similar such coatings. For
example, in a preferred embodiment the filler comprises calcium
carbonate that has been treated with calcium stearate to render it
hydrophobic and to prevent agglomeration or clumping.
[0046] Generally, the filler is included in the film layer in an
amount suitable to provide the desired breathability. Generally,
the filler may be employed in an amount of from about 25 to about
75 weight percent, based on the total weight of the microporous
coating. To achieve the desired level of MVTR for the present
invention, it is preferred that the polymer and pore-forming filler
blend comprise at least 40% by weight filler, and most desirably at
least 50% by weight filler. The polymer composition may also
include additional colorants or pigments, such as titanium dioxide,
as well as conventional stabilizers and antioxidants, such as UV
stabilizers, thermal stabilizers, hindered amine light stabilizer
compounds, ultraviolet absorbers, antioxidants and
antimicrobials.
[0047] In one embodiment of the invention, the composite sheet
material 10 is manufactured by extrusion coating the substrate 12
with a composition comprising a polymer composition and a filler to
form film layer 14 on the substrate, followed by manipulating the
composite sheet material 10 to render the film layer microporous,
and hence breathable. Suitable equipment for carrying out this
process is shown schematically in FIG. 2. The substrate 12 is
unwound from a supply roll 20 and is directed onto and around a
rotating chill roll 22. A cooperating pressure roll 24 defines a
pressure nip with the chill roll 22. The polymer composition is
extruded in the form of a film 14 of molten polymer from a slot die
26 of an extruder 27 directly into the nip defined between the
cooperating rolls 22, 24. As the polymer film 14 and the substrate
12 advance around the chill roll 22, the molten polymer composition
cools and solidifies to form a substantially continuous polymer
film layer adhered to one surface of the substrate 12. At this
point, the nonwoven web and film composite is substantially
impermeable to moisture vapor. The composite is made microporous by
stretching the material in the machine direction, or the
cross-machine direction or in both the machine direction and the
cross-machine direction. The fabric can be rolled-up and the
stretching can be carried out in a separate subsequent operation,
or alternatively, the stretching can be carried out in-line with
the extrusion coating operation, as shown in FIG. 2. An exemplary
process that may be used to prepare a composite sheet material in
accordance with the present invention are described in commonly
assigned U.S. Patent Publication No. 2004/0029469, the contents of
which are incorporated by reference.
[0048] As noted above, the polymer composition, in combination with
the filler, can be rendered microporous by a relatively small
degree of moving, twisting, calendering, or otherwise physically
treating the composite sheet material. In some embodiments, the
mere presence of the filler in the film layer is sufficient to
render the film layer microporous. In particular, it has been
surprisingly discovered that even a small amount of tension applied
to the composite sheet material 10 may be enough to render the
sheet material breathable. Other methods of rending the film layer
microporous may include physical manipulation of the composite
sheet material 10, such as bending, twisting, or biasing, can be
used to enhance the breathability of the coated substrate.
[0049] Various stretching techniques can also be employed to
develop the micropores in the composite sheet material 10. A
particularly preferred stretching method is a process known as
"incremental stretching". In an incremental stretching operation,
the sheet material is passed through one or more cooperating pairs
of intermeshing grooved or corrugated rolls which cause the sheet
material to be stretched along incremental zones or lines extending
across the sheet material. The stretched zones are separated by
zones of substantially unstretched or less stretched material. The
incremental stretching can be carried out in the cross machine
direction (CD) or the machine direction (MD) or both, depending
upon the design and arrangement of the grooved rolls. Example of
apparatus and methods for carrying out incremental stretching are
described in U.S. Pat. Nos. 4,116,892; 4,153,751; 4,153,664; and
4,285,100, incorporated herein by reference.
[0050] FIG. 2 illustrates equipment suitable for a continuous
in-line stretching operation using first and second pairs of
intermeshing rolls. The first, pair of intermeshing rolls 31, 32 is
provided with a grooved surface configured for achieving
incremental stretching in the cross-direction (CD) of the material.
The grooves extend circumferentially around the rolls and produce a
series of alternating stretched and non-stretched zones extending
linearly along the machine direction of the composite material. The
amount of incremental stretching is controlled by varying the
engagement depth of the intermeshing rolls. The stretching
operation is carried generally in accordance with the teachings of
U.S. Pat. No. 5,865,926, the disclosure of which is incorporated
herein by reference.
[0051] Preferably, the fabric is subjected to stretching in the
machine direction as well as in the cross-direction. For this
purpose, the fabric is run through a second set of rolls 33, 34
designed for achieving MD stretching. The second pair of
intermeshing rolls 33, 34 have a grooved surface configured for
achieving stretching in the machine direction (MD) of the material,
with the grooves extending generally parallel to the rotational
axis of the rolls. The additional stretching operation in the
machine direction increases the moisture vapor transmission
properties of the material and provides an aesthetically pleasing
surface appearance.
[0052] It has been discovered that the fire resistance of the
composite sheet material, and hence a roofing system including the
composite sheet material of the present invention, can be
significantly improved by applying the film layer at a relatively
high basis weight. In particular, it has been discovered that the
composite sheet material employing the above described film layer
that is applied at a basis weight of at least 70 g/m.sup.2 can help
provide a roofing structure, such as a shingled roof, with fire
resistance so that the roof can meet the Fire Resistance
requirements of ASTM E 108-07a, Class A. As noted previously, Class
A tests are applicable to roof coverings that are effective against
severe test exposure, afford a severe degree of fire protection to
the roof deck, do not slip from position, and do not present a
flying brand hazard. In one embodiment, the film layer is
preferably applied to the nonwoven substrate at a minimum basis
weight of 70 g/m.sup.2, and most desirably, from about 70 to 100
g/m.sup.2, and even more desirably, from about 75 to 85 g/m.sup.2.
In some embodiments, the film can be applied at a basis of less
than 70 g/m.sup.2, such as at 50 g/m.sup.2 or greater, although not
necessarily with equivalent results. The resulting composite sheet
material has an overall basis weight of from about 90 to 205
g/m.sup.2, and more desirably from about 140 to 205 g/m.sup.2 and a
MVTR of at least 35 g/m.sup.2/24 hr. at 50% relative humidity and
23.degree. C. (73.degree. F.), and more desirably and MVTR of at
least 100. In one embodiment, the composite sheet material has an
MVTR of from about 1 to 411, and desirably from about 7 to 205, and
most desirably from about 34 to 137 g/m.sup.2/24 hr. at 50%
relative humidity and 23.degree. C. (73.degree. F.). The product
preferably also has a Gurley porosity of at least 400 seconds and a
hydrostatic head of at least 55 cm.
[0053] Composite sheet materials in accordance with the present
invention, desirably exhibit excellent strength and tear resistant
properties so that the sheet materials are particularly useful as a
roof underlayment material where the underlayment may be subject to
frequent foot traffic as well as other conditions that could damage
conventional underlayment materials. In one embodiment, the
composite sheet material a grab tensile strength from about 100-150
Newtons, and preferably from about 125 to 140 Newtons, and more
preferably, from about 130-140 Newtons in the machine direction
(CD). Embodiments of the composite sheet material may also have
grab tensile strength in the cross direction from about 80 to 140
Newtons, and preferably from about 100 to 140 Newtons, and more
preferably, from about 130 to 140 Newtons. In addition to excellent
tensile strength properties, it is also desirable for the composite
sheet material to be tear resistant. For example, the composite
sheet material desirably has a Trapezoidal Tear Strength in at
least one of the machine or cross directions that is from about 30
to 45 Newtons, and desirably from about 34-42 Newtons, and more
desirably from about 35 to 40 Newtons. Grab Tensile Strength is
measured in accordance with ASTM D 1682, and trapezoidal tear
strength is measured in accordance with ASTM D 4533.
[0054] In an alternative embodiment, a composite sheet material in
accordance with the present invention can be prepared in which the
film layer is inherently breathable and therefore does not require
the presence of micropores or pore-forming fillers to provide the
desired breathability. In particular, in one embodiment the
composite sheet material comprises a nonwoven substrate onto which
a breathable monolithic film is extrusion coated. In a preferred
embodiment, the film forming polymer composition comprises a blend
of polypropylene and from about 20 to 30% by weight of a
co-polyether amide, a block co-polyether ester, or a combination
thereof. Additionally, the polymer composition will include one or
more compatibilizers. Examples of compatibilizers include waxes,
such as Epolene E-43 and fluoropolymer processing aids (PPA).
[0055] Preferably, the monolithic film has a MVTR of at least 35
g/m.sup.2/24 hr. at 50% relative humidity and 23.degree. C.
(73.degree. F.), and more desirably and MVTR of at least 100. The
product preferably also has a Gurley porosity of at least 400
seconds and a hydrostatic head of at least 55 cm. The substrate is
as described above with a spunbond polypropylene nonwoven fabric
being preferred.
[0056] From the foregoing discussion, it can be seen that the
present invention provides a composite sheet material that is
particularly useful as an underlayment in roofing applications. In
this regard, FIG. 3 illustrates a building having a roofing system
that is in accordance with the present invention is illustrated and
is indicated generally by reference character 50. A portion of the
roofing system is not shown so that the reader can see various
components of the roofing system. The roofing system 52 includes an
exterior roof surface 54, also referred to as a roof deck, a layer
of underlayment material 56 attached to the roof deck, and a
multiplicity of courses of roofing shingles 58 attached and
overlying the underlayment material.
[0057] The underlayment material 56 comprises composite sheet
material 10. Preferably, the composite sheet material is positioned
on the roof deck so that the surface 18 of the substrate faces
upwardly and the film layer of the composite sheet material faces
towards the roof deck. As noted above, surface 18 provides a
non-skid surface that can help prevent slippage of workers
installing the roofing system. Additionally, the high strength
properties of the nonwoven substrate help to prevent the composite
sheet material from being torn or damaged during the installation
process.
Test Methods
[0058] In the description above and in the non-limiting examples
that follow, the following test methods were employed to determine
various reported characteristics and properties. ASTM refers to the
American Society for Testing and Materials, AATCC refers to the
American Association of Textile Chemists and Colorists, INDA refers
to the Association of the Nonwovens Fabrics Industry, and TAPPI
refers to the Technical Association of Pulp and Paper Industry.
[0059] The following tests are hereby incorporated by
reference.
[0060] Basis Weight is a measure of the mass per unit area of a
sheet and was determined by ASTM D-3776, which is hereby
incorporated by reference, and is reported in g/m.sup.2. Fabric
thickness is measured in accordance with ASTM D 1777--Standard Test
Method for Thickness of Textile Materials (1996).
[0061] Air Leakage Rate is a measure of determining air leakage
across a specimen under specified differential pressure conditions
across the specimen. This test is carried out in accordance with
ASTM E 283 and E 2178.
[0062] Grab Tensile Strength is a measure of breaking strength of a
fabric when subjected to unidirectional stress. This test is
carried out in accordance with ASTM D 1682.
[0063] Gurley Porosity is a measure of the resistance of the sheet
material to air permeability, and thus provides an indication of
its effectiveness as an air barrier. It is measured in accordance
with TAPPI T-460 (Gurley method). This test measures the time
required for 100 cubic centimeters of air to be pushed through a
one-inch diameter sample under a pressure of approximately 4.9
inches of water. The result is expressed in seconds and is
frequently referred to as Gurley Seconds.
[0064] Hydrostatic Head (hydrohead) is a measure of the resistance
of a sheet to penetration by liquid water under a static pressure.
The test is conducted according to AATCC-127, which is hereby
incorporated by reference, and is reported in centimeters.
[0065] Moisture Vapor Transmission Rate (MVTR) is determined by
ASTM E 96, Standard Test Methods for Water Vapor Transmission of
Materials; 1995, Procedure A. Peel Strength is measured in
accordance with ASTM D 2724.
[0066] Tear Strength is measured in accordance with ASTM D 4533
(trapezoidal tear), tensile strength measurements are determined
according to ASTM D 5034-95.
[0067] Slip Resistance is measured in accordance with ASTM
F-1679.
[0068] External Fire Resistance of Roof Covering Systems is
measured in accordance with ASTM E 108-07a, Standard Test Methods
for Fire Tests of Roof Coverings: Class A Burning Brand and
Intermittent Flame.
EXAMPLES
[0069] TYPAR.RTM. 3251 material, a spunbonded polypropylene
nonwoven fabric produced by Fiberweb, Inc. of Old Hickory, Tenn.,
was used as the fibrous nonwoven substrate for producing a high
MVTR extrusion coated composite sheet material. TYPAR.RTM. 3251
material is a spunbond polypropylene nonwoven fabric having a basis
weight of 84 g/m.sup.2, a thickness of 0.422 mm (12.7 mils), an MD
grab tensile strength of 467 N (105 lbs.), a CD grab tensile
strength of 472 N (106 lbs.), and a trapezoidal tear strength of
182 N (41 lbs.) in the MD and 165 N (37 lbs.) in the CD. This
substrate was extrusion-coated with a polyolefin polymer
composition that is a blend of polypropylene and polyethylene and
that contains about 50 percent by weight calcium carbonate filler.
The polymer film was extruded onto the substrate at a basis weight
of 80 g/m.sup.2. The resulting composite was incrementally
stretched in the MD and CD using equipment similar to that shown in
FIG. 2. The physical properties of samples of the composite sheet
material were evaluated. Average values for the samples are shown
in Table 1 below.
TABLE-US-00001 TABLE 1 Test Result Film Basis Weight (g/m2) 80 Peel
Adhesion (g/1 inch) >500 Hydrohead (cm) >100 MVTR (g/24 hr
m.sup.2) 72 Gurley Porosity >400 Thickness, mm (mils) 19 Grab
Tensile, MD N (lbf/in) 178 (40) Grab Tensile, CD N (lbf/in 165
(37)
[0070] In the following Example, the non-skid properties of the
composite sheet material were compared to those of 4 commercially
available underlayment materials. The three synthetic
underlayments: Titanium UDL, Palasade and REX Synfelt, are all
woven slit film (e.g., polypropylene) substrates extrusion coated
on one or both side with a polymeric coating, such as polypropylene
or a blend. The Titanium product has the coating textured on one
side to improved slip performance, while the Palisades has been
laminated to a pointbonded nonwoven with printed raised dots to
also improve slip performance. The REX Synfelt underlayment has not
been specifically altered to improve coefficient of friction. The
final sample is 15 pound felt paper, which is commonly a kraft
paper impregnated with petroleum byproducts. The results are
summarized in TABLE 2 below.
TABLE-US-00002 TABLE 2 Average Average Wet Surface Tested Dry (COF)
(Slip-Resistance Index) Inventive Composite 0.88 0.73 Sheet
Material Titanium .TM. UDL 0.87* 0.60* Palasade .TM. 0.89 0.52 REX
.TM. Synfelt >1.00 0.47 GAF ShingleMate #15 >1.00 0.69
*Directional slip-resistance was evident with this product.
[0071] The fire resistance of the composite sheet material was also
tested in accordance with ASTM E 108-07a. The sheet material passed
the Class A Burning Brand Test and Class A Intermittent Flame
Test.
[0072] Many modifications and other embodiments of the inventions
set forth herein will come to mind to one skilled in the art to
which these inventions pertain having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. Therefore, it is to be understood that the inventions are
not to be limited to the specific embodiments disclosed and that
modifications and other embodiments are intended to be included
within the scope of the appended claims. Although specific terms
are employed herein, they are used in a generic and descriptive
sense only and not for purposes of limitation.
* * * * *