U.S. patent application number 13/159659 was filed with the patent office on 2011-11-03 for impact resistant sheet material.
This patent application is currently assigned to Fiberweb, Inc.. Invention is credited to Arthur Henry Cashin, Imad Mohammad Qashou.
Application Number | 20110269363 13/159659 |
Document ID | / |
Family ID | 40090401 |
Filed Date | 2011-11-03 |
United States Patent
Application |
20110269363 |
Kind Code |
A1 |
Cashin; Arthur Henry ; et
al. |
November 3, 2011 |
Impact Resistant Sheet Material
Abstract
The present invention provides an impact resistant sheet
material that helps provide exterior walls of a building with
resistance to impacts so that the building structure can meet
building standards, such as the Miami-Dade County Large Missile
Impact Test, for resisting impacts in high wind areas. In one
embodiment, sheet material comprises an impact resistant layer that
attached to fibrous substrate. The impact resistant layer provides
impact resistance to the sheet material so that a wall structure
employing the sheet material is able to successfully withstand an
impact from a projectile comprising a 9 pound, 7 foot two-by-four
("2.times.4") traveling at a speed of at least 34 miles per hour.
The impact resistant sheet material may comprise a moisture vapor
permeable, water-impermeable barrier layer having a hydrohead of at
least 55 cm and a moisture vapor transmission rate of at least 35
g/m.sup.2/day. Such a sheet material is particularly useful in
barrier applications, such as a house wrap.
Inventors: |
Cashin; Arthur Henry;
(Nashville, TN) ; Qashou; Imad Mohammad;
(Nashville, TN) |
Assignee: |
Fiberweb, Inc.
|
Family ID: |
40090401 |
Appl. No.: |
13/159659 |
Filed: |
June 14, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11837100 |
Aug 10, 2007 |
7984591 |
|
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13159659 |
|
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Current U.S.
Class: |
442/394 ; 156/71;
428/221; 442/286 |
Current CPC
Class: |
Y10T 442/601 20150401;
F41H 5/0478 20130101; B32B 5/12 20130101; B32B 27/02 20130101; B32B
27/12 20130101; B32B 5/26 20130101; B32B 7/12 20130101; Y10T
442/674 20150401; B32B 2307/7265 20130101; F41H 5/0471 20130101;
B32B 2307/558 20130101; E04C 2/34 20130101; E04C 2/246 20130101;
B32B 27/32 20130101; B32B 2307/726 20130101; B32B 2266/0228
20130101; B32B 5/022 20130101; Y10T 428/249921 20150401; B32B
2307/54 20130101; B32B 13/14 20130101; B32B 5/245 20130101; B32B
5/18 20130101; E04H 9/10 20130101; Y10T 442/3008 20150401; Y10T
442/3854 20150401 |
Class at
Publication: |
442/394 ;
442/286; 428/221; 156/71 |
International
Class: |
B32B 27/12 20060101
B32B027/12; E04F 13/00 20060101 E04F013/00 |
Claims
1. An impact resistant sheet material comprising: a moisture vapor
permeable, water-impermeable, polymeric barrier layer having a
hydrohead of at least 55 cm and a moisture vapor transmission rate
of at least 35 g/m.sup.2/day; and an impact resistant layer
attached to the barrier layer, the impact resistant layer
comprising a fabric layer having at least two pluralities of
strands that extend in different directions and intersect each
other, the impact resistant layer having a tensile strength of at
least 445 Newtons, an elongation that is between 2 and 20 percent,
and an Impact Resistance as measured by the Free-Falling Dart
Method of greater than about 0.7 pounds.
2. The impact resistant sheet material of claim 1, wherein the
impact resistant layer has an elongation that is between 5 and
15%.
3. The impact resistant sheet material of claim 1, wherein the
impact resistant layer has an elongation that is between 5 and
12%.
4. The impact resistant sheet material of claim 1, wherein the
barrier layer comprises a nonwoven or woven material.
5. The impact resistant sheet material of claim 1, wherein the
barrier layer comprises a nonwoven substrate comprising polymeric
fibers randomly disposed and bonded to one another, and a
breathable polymeric film layer overlying one surface of the
nonwoven substrate and intimately bonded thereto.
6. The impact resistant composite sheet material of claim 5,
wherein the film layer comprises an extrusion coated polyolefin,
and the nonwoven substrate comprises substantially continuous
spunbond polypropylene filaments.
7. The impact resistant sheet material of claim 1, wherein the
barrier layer comprises a fibrous substrate having a surface to
which a breathable monolithic polymeric film layer is adhered
thereto.
8. The impact resistant sheet material of claim 7, wherein the
fibrous substrate is selected from the group consisting of spunbond
webs, woven slit films, carded webs, meltblown webs, flashspun
webs, woven, and extruded webs.
9. The impact resistant sheet material of claim 1, wherein the
sheet material has a Mullen burst strength of at least 175 pounds
and an Impact Resistance as measured by the Free-Falling Dart
Method of greater than about 1 pound.
10. The impact resistant sheet material of claim 9, wherein the
sheet material has an Impact Resistance as measured by the
Free-Falling Dart Method of greater than 2 pounds.
11. The impact resistant sheet material of claim 1, wherein the
impact resistant layer includes a first plurality of strands that
extend in a first direction, a second plurality of strands that
extend in a second direction that is different than the first
direction, and third and fourth pluralities of strands that both
extend at an angle with respect to the first plurality of strands
and are oriented at opposite angles with respect to each other so
they intersect each other in an X-like pattern.
12. An impact resistant sheet material comprising a moisture vapor
permeable, water impermeable composite sheet material having
barrier properties making it suitable for use as a housewrap, the
sheet material comprising: a fibrous substrate; a breathable
polymeric film layer overlying one surface of the substrate and
intimately bonded thereto, the film layer having a moisture vapor
transmission rate (MVTR) of at least 35 g/m.sup.2/day at 50%
relative humidity and 23.degree. C. and a hydrostatic head of at
least 55 cm; and an impact resistant layer attached to a surface of
the substrate opposite the film layer, the impact resistant layer
comprising a fabric having at least two pluralities of intersecting
strands that extend in different directions with respect to each
other, wherein the impact resistant layer has a tensile strength of
at least 445 Newtons and an elongation that is less than 20 percent
and an Impact Resistance as measured by the Free-Falling Dart
Method of greater than about 2 pounds.
13. The impact resistant sheet material of claim 12, wherein the
impact resistant layer has an elongation that is between about 6
and 10%.
14. The impact resistant sheet material of claim 12, wherein the
impact resistant layer has a tensile strength that is from about
600 to 1200 N.
15. A method of constructing an impact resistant wall structure
comprising fastening an exterior surface of a sheathing material
mounted on an exterior side of the wall structure with an impact
resistant sheet material, the impact resistant sheet material
comprising a moisture vapor permeable, water-impermeable polymeric
barrier layer having a hydrohead of at least 55 cm and a moisture
vapor transmission rate of at least 35 g/m.sup.2/day; and an impact
resistant layer attached to the barrier layer, the impact resistant
layer comprising a fabric layer having at least two pluralities of
strands that extend in different directions and intersect each
other, the impact resistant layer having a tensile strength of at
least 445 Newtons, an elongation that is between 2 and 20 percent,
and wherein the wall structure is able to successfully withstand an
impact from a projectile comprising a 9 pound, 7 foot two-by-four
traveling at a speed of at least 34 miles per hour without
penetration of the wall structure.
16. The method of claim 15, wherein the impact resistant layer has
an elongation that is between 5 and 15%.
17. The method of claim 15, wherein the impact resistant layer has
an elongation that is between about 6 and 10%.
18. The method of claim 15, wherein the wall structure is capable
of passing the Large Missile Impact Resistance Test according to
TAS 201-94, and the Cyclic Wind Pressure Loading Test according to
TAS 203-94.
19. The method of claim 15, the barrier layer comprises a fibrous
substrate having a surface to which a breathable polymeric film
layer is adhered thereto.
20. The method of claim 19, wherein the fibrous substrate is
selected from the group consisting of spunbond webs, woven slit
films, carded webs, meltblown webs, flashspun webs, woven, and
extruded webs.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/837,100, filed Aug. 10, 2007, the contents
of which are both incorporated by reference in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a sheet material
and in particular to an impact resistant sheet material.
BACKGROUND OF THE INVENTION
[0003] In regions that are susceptible to high winds, such as
hurricane force winds, there is a strong desire and need to protect
buildings from impacts resulting from wind-borne debris. For
example, the state of Florida has set standards that buildings
situated in High Velocity Hurricane Zones (e.g., Miami-Dade and
Broward Counties) must be provided with protection against
wind-borne debris caused by hurricanes. In particular, Miami-Dade
County has implemented strict test protocols for wind-borne debris
that require walls and building panels to withstand certain
impacts, such as large or small-missile impacts. A product is
declared large-missile resistant if it can withstand various
impacts with a piece of lumber weighing approximately 9 pounds,
measuring two-by-four in size ("2.times.4"), and traveling at a
speed of 50 feet per second (34 mph). Products that are able to
meet the Miami-Dade County test protocols are issued a Miami-Dade
County Notice of Acceptance (NOA).
[0004] Various types of sheet materials have been used in the
construction of buildings as a barrier fabric to block water and
air while allowing transmission of moisture vapor from the building
interior. These so-called housewrap products are typically applied
over the sheathing layer of the building and beneath the exterior
surface layer of brick or siding. Generally, housewrap products are
flexible, inexpensive, and relatively easy to install. However,
they typically offer little to no impact resistance and are
susceptible to being punctured or torn. As a result, these products
are unable to meet the Miami-Dade County requirements for impact
resistance.
[0005] To meet the Miami-Dade County impact-resistant requirements,
various products have been developed, such as steel or cementitious
wall panels. For example, Miami-Dade County NOA No. 02-1216.01
describes an approved impact resistant wall panel comprising rib
roll-formed galvanized steel that is made by Reynolds Metal Co.
This product is generally expensive to produce and install, as well
as being relatively heavy and cumbersome. Other commercially
available products have been developed that are directed to
composite structures that include one or more cementitious layers,
a foam core, and a reinforcing mesh. For example, U.S. Pat. No.
6,119,422 describes a multilayered impact resistant building panel
having an insulating foam core that is sandwiched between a
fiberglass mesh reinforced cementitious panel and a plywood sheet,
and an impact resistant heavy and thick nylon mesh adhered between
the cementitious panel and the foam core. These wall panels are
also expensive to produce and difficult to install.
[0006] Thus, there still exists a need for a product that can meet
the Miami-Dade County impact-resistant requirements while being
relatively inexpensive and easy to install.
BRIEF SUMMARY OF THE INVENTION
[0007] The present invention provides an impact resistant sheet
material that can help provide a building structure, such as an
exterior wall or panel, with resistance to exterior impacts so that
the building structure can meet building standards, such as the
Miami-Dade County Large Missile Impact Test, for resisting impacts
in high wind areas.
[0008] In one embodiment, the impact resistant sheet material
comprises an impact resistant layer that is attached to a fibrous
substrate. The impact resistant layer provides impact resistance to
the sheet material so that the sheet material is able to
successfully withstand an impact from a projectile comprising a 9
pound, 7 foot two-by-four piece ("2.times.4") of lumber traveling
at a speed of at least 34 miles per hour without penetration of the
sheet material. In one embodiment, the impact resistant sheet
material of the present invention has a puncture strength of about
1500 to 7,500 psi; an Impact Resistance as measured by the
Free-Falling Dart Method of greater than about 0.7 pounds; and a
Mullen burst strength of about 175 pounds (lbs) or greater.
[0009] In some embodiments, the impact resistant layer comprises at
least two pluralities of strands that extend in different
directions and that intersect and are bonded to each other at
points of contact. In one embodiment, the impact resistant layer
includes a first plurality of strands that extend in a first
direction, a second plurality of strands that extend in a second
direction that is different than the first direction, and third and
fourth pluralities of strands that both extend at an angle with
respect to the first plurality of strands and are oriented at
opposite angles with respect to each other so they intersect each
other in an X-like pattern. Preferably, the impact resistant layer
has a tensile strength of at least 445 Newtons and an elongation
that is between 2 and 20 percent to thereby provide impact
resistance to the sheet material so that the sheet material is able
to successfully withstand impacts from wind-borne debris.
[0010] In one particular embodiment, the present invention is
directed to an impact resistant sheet material having a breathable
barrier layer. For example, the impact resistant sheet material may
comprise a moisture vapor permeable, air and water-impermeable
barrier layer having a hydrohead of at least 55 cm and a moisture
vapor transmission rate of at least 35 g/m.sup.2/day. Such a sheet
material is particularly useful in barrier applications, such as a
housewrap.
[0011] In one embodiment, the barrier layer comprises a breathable
barrier film that is attached to a surface of a fibrous substrate,
such as spunbond webs, woven slit films, carded webs, meltblown
webs, flashspun webs, woven, and extruded webs, and the like.
Preferably, the barrier layer comprises a nonwoven substrate
comprising polymeric fibers randomly disposed and bonded to one
another, and a microporous polymeric film layer overlying one
surface of the nonwoven substrate and intimately bonded thereto. In
one particular embodiment, the film layer can comprise a polyolefin
that is extrusion-coated onto a nonwoven substrate comprised of
substantially continuous spunbond polypropylene filaments.
[0012] In another embodiment, the present invention is directed to
a safe room that can be used in a building structure to provide
shelter to occupants during high wind storm so that the occupants
can be sheltered from wind-borne debris. For example, the safe room
may comprise a room disposed in a building structure that has a
plurality of walls that are substantially covered with the impact
resistant sheet material so that wind-borne debris is prevented
from penetrating through the walls of the safe room and striking
the occupants therein.
[0013] In addition to providing the desired impact resistance, the
impact resistant sheet material of the present invention can be
designed to be lightweight, flexible, and in some embodiments is
able to be cut with conventional cutting instruments, such as a
scissors. As a result, the sheet material can be used in a wide
variety of applications and can be relatively easily installed to
exterior walls in the same way that traditional housewrap materials
are applied. Further, it is unexpected that the use of the
relatively lightweight and flexible sheet material of the present
invention is able to meet the requirements of the Miami-Dade County
Large Missile Impact Test. This is particularly true because
conventional materials utilized in such applications typically
provide impact resistance through rigidity and harness (e.g.,
corrugated steel sheeting or concrete/cinder block).
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0014] 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:
[0015] FIG. 1 is a perspective view of a house that includes the
impact resistant sheet material of the present invention and in
which a portion of the siding has been removed to show the
underlying impact resistant sheet material;
[0016] FIG. 2A illustrates a projectile impacting an exterior wall
of a building that does not include the impact resistant sheet
material;
[0017] FIG. 2B illustrates a projectile impacting an exterior wall
of a building that does include the impact resistant sheet
material;
[0018] FIG. 3 is a perspective view of an embodiment of the impact
resistant sheet material in which the impact resistant sheet
material includes a fibrous layer to which an impact resistant
layer has been attached;
[0019] FIG. 4 is a perspective view of an embodiment of the impact
resistant sheet material in which the impact resistant layer
comprises a plurality of intersecting and interwoven strands that
are arranged perpendicular to each other to form a grid-like
pattern;
[0020] FIG. 5 is a perspective view of an embodiment of the impact
resistant sheet material in which the impact resistant layer
comprises a plurality of intersecting and interwoven strands having
a tri-axial pattern;
[0021] FIG. 6 is a cross-sectional side view of the impact
resistant sheet material of FIG. 4 taken along line 6-6 of FIG.
4;
[0022] FIG. 7 is a perspective view of a composite wall panel that
includes a substrate to which the impact resistant sheet material
of the present invention has been attached;
[0023] FIG. 8 is a perspective view of a building in which the
exterior walls of the building are in ghost form to reveal an
interior safe room that is protected with an embodiment of the
impact resistant sheet material; and
[0024] FIG. 9 is a perspective view of a wall panel that includes
the impact resistant sheet material of the present invention and
that was tested in accordance with the Miami-Dade County Impact
Resistance test protocols.
DETAILED DESCRIPTION OF THE INVENTION
[0025] 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 invention is shown. Indeed,
the invention 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.
[0026] The present invention provides an impact resistant sheet
material that can help protect structures, such as buildings, from
damage that may result from impacts with wind-borne debris moving
at relatively high rates of speed. In one embodiment, the impact
resistant sheet material can help provide a building structure,
such as an exterior wall or panel, with resistance to exterior
impacts so that the building structure can meet building standards,
such as the Miami-Dade County Large Missile Impact Test, for
resisting impact in high wind areas. Under the Miami-Dade County
Large Missile Impact Test, a building structure, such as a wall or
panel, must be resistant to penetration from the impact on the
exterior side of the panel of a wooden two-by-four ("2.times.4"),
approximately eight feet long, weighing about 9 pounds and moving
endwise at 34 miles per hour. In order to pass the Missile Impact
Test, the panel structure subjected to such an impact must be able
to withstand a cyclic pressure differential test in which a vacuum
pressure is applied to the panel structure before and after the
panel has sustained an impact from the test projectile. Under the
cyclic pressure differential test, the wall panel must withstand at
least one-third of the total vacuum pressure applied to the panel
prior to the impact without failure. Specifics of the Miami-Dade
County Large Impact Missile Test are discussed in greater detail
below.
[0027] FIG. 1 illustrates an embodiment of the present invention
wherein the impact resistant sheet material 10 is being utilized as
a housewrap that is attached to the exterior wall sheathing of a
building 12 (e.g., a house). In the illustrated embodiment, a
portion of the building's exterior siding 14 has been removed to
provide the reader with a view of the impact resistant sheet
material 10. As discussed in greater detail below, the impact
resistant sheet material is capable of absorbing impacts from
objects moving at relatively high rates of speed without
penetration. As a result, the impact resistant sheet material of
the present invention helps prevent such objects from penetrating
through the exterior walls of the building and entering into the
building's interior space.
[0028] FIGS. 2A and 2B illustrate two similarly constructed
exterior wall structures with the exception that the exterior wall
depicted in FIG. 2A does not include the impact resistant sheet
material, whereas the exterior wall of FIG. 2B does include the
impact resistant sheet material of the present invention. In FIG.
2A, the exterior wall 16 of a building is in the process of being
impacted by a wind-borne object 18, for example a piece of lumber,
that is moving at a relatively high rate of speed. As shown in FIG.
2A, the exterior siding 14 of the building and the underlying
structure offers little to no impact resistant to the object. As a
result, winds of sufficient strength can propel the object through
the outer exterior wall 16 of the building, which can result in the
object penetrating into the building's interior. As shown in FIG.
2B, an exterior wall 16 that includes the impact resistant sheet
material 10 provides impact resistance to the exterior wall and
helps prevent the object 18 from penetrating through the exterior
wall and into the building. Although the force of the impact may
damage some portions of the exterior wall, such as the siding 14 or
stucco, the impact resistant sheet material has absorbed much of
the impact and has prevented the object from penetrating through
exterior wall of the building. As a result, a wall structure
employing the impact resistant sheet material of the present
invention is capable of meeting the requirements of the Miami-Dade
County Large Missile Impact Test and is particularly useful in
regions that are susceptible to high winds.
[0029] In housewrap and similar applications, it is generally
desirable for the impact resistant sheet material to be both vapor
permeable and water impermeable while also providing a barrier to
air infiltration. In this regard, FIG. 3 illustrates an embodiment
of the impact resistant sheet material 10 in which the impact
resistant sheet material includes an impact resistant layer 20 to
which a barrier layer 22 is attached. The impact resistant layer 20
helps provide impact absorbing properties so that the impact
resistant sheet material 10 can sustain impacts from objects moving
at relatively high speeds without rupture. As discussed in greater
detail below, the barrier layer 22 may comprise a fibrous substrate
24 that is moisture vapor permeable and impermeable to water and
air leakage. In some embodiments, the fibrous substrate may be
coated with a breathable, liquid impermeable coating, such as a
film layer. In other embodiments, the barrier layer may comprise a
combination of a fibrous substrate and a breathable,
water-impermeable film layer. For example, FIGS. 4 and 5 illustrate
embodiments of the invention in which the impact resistant sheet
material 10 includes a fibrous substrate 24 having an outer
moisture vapor permeable, water-impermeable film layer 26 adhered
on one side thereof and the impact resistant layer 20 attached to
the opposite side. In still other embodiments, the impact resistant
sheet material may be used without a barrier layer. These and other
embodiments of the invention are discussed in greater detail
below.
[0030] Generally speaking, the breathability of the impact
resistant sheet material may be controlled as desired for the
intended application of the materials. In barrier applications,
such as a housewrap, it is generally desirable that the impact
resistant 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
impact resistant sheet material has a MVTR that is at least 100
g/m.sup.2/day. In some embodiments, the impact resistant 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,
housewrap 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 is also desirable for the impact
resistant sheet material to be impermeable to air flow. Preferably,
the impact resistant 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."
[0031] In some embodiments, the impact resistant sheet material
preferably also has a Gurley porosity of at least 400 seconds and a
hydrostatic head of at least 55 cm. Gurley porosity and hydrostatic
head are measured in accordance with the test procedures described
below under the section entitled "Test Methods."
[0032] As discussed above, the impact resistant layer 20 provides
sufficient impact absorbing performance so that the impact
resistant sheet material 10 is able to meet the requirements of the
Miami-Dade Large Missile Impact Test. Preferably, the impact
resistant sheet material is able to withstand an impact of a
two-by-four ("2.times.4") piece of lumber weighing approximately 9
pounds, traveling at a speed of 50 feet per second (34 mph). For
example, the impact resistant sheet material 10 is desirably
capable of sustaining an impact energy from a projectile, such as
at two-by-four ("2.times.4"), of at least 65 ft-lbs/sec/in.sup.2
without permitting the projectile to penetrate through the impact
resistant sheet material.
[0033] Preferably, the impact resistant sheet material of the
present invention has a puncture strength of about 1500 to 7,500
psi, and in particular from about 2000 to 6,000 psi, and more
particularly from about 3,000 to 5,000 psi. In some embodiments,
the impact resistant sheet material has an Impact Resistance as
measured by the Free-Falling Dart Method of greater than 0.7 lbs,
such as greater than 1 lb. and in particular greater than about 2
lbs. In one particular embodiment, the impact resistance sheet
material has an impact resistance of at least 1 to 5 lbs, and more
particularly, from about 2 to 4 lbs. The impact resistant sheet
material of the present invention may also have Mullen burst
strength of at least 100 lbs, and in particular greater than 300
lbs. or greater than 500 lbs. Preferably, the impact resistance
sheet material has a Mullen burst strength from about 100 to 750
lbs., and more preferably from about 300 to 550 lbs. Impact
Resistance according to the Free-Falling Dart Method, puncture
resistance, and Mullen burst strength are measured in accordance
with the test procedures described below under the section entitled
"Test Methods."
[0034] As shown in FIGS. 3-5, the impact resistant layer 20 may
comprise a plurality of intersecting strands (collectively referred
to by reference number 28) that extend across a surface of the
fibrous substrate and are attached to each other at points of
contact. In one embodiment, the impact resistant layer 20 comprises
a plurality of substantially parallel strands that extend
substantially in a first direction and a second plurality of
substantially parallel strands extending in a second and different
direction. As a result, the first and second strands are woven or
attached to each other at multiple points of contact to thereby
form a strong and coherent scrim-like material. In some
embodiments, the plurality of strands can be adhesively or
thermally bonded to each other. In one preferred embodiment, the
first and second pluralities of strands are woven together to
provide strength and integrity to the impact resistant layer
20.
[0035] In the embodiments illustrated in FIGS. 3 and 4, the impact
resistant layer 20 comprises a first plurality of spaced apart
parallel strands 30 extending in a vertical direction (e.g. the
machine or longitudinal direction), and a second plurality of
spaced-apart parallel strands 32 extending in a horizontal
direction (e.g. the cross or transverse direction) that are
substantially perpendicular to each other, and thereby define a
woven scrim layer having a grid-like pattern. Collectively, strands
28 intersect with one another and are bonded to each other to form
a strong and coherent scrim-like material that is capable
withstanding impacts from objects moving at relatively high rates
of speed.
[0036] In an alternative embodiment, as shown in FIG. 5, the impact
resistant layer 20 may have a weave pattern in which the impact
resistant layer includes three or more pluralities of strands that
are arranged and extend in three or more different directions with
respect to each other. In the embodiment in FIG. 5, the impact
resistant layer includes a first plurality of strands 30 that
extend in the vertical direction (e.g., machine direction), a
second plurality of strands 32 that extend in the horizontal (e.g.
cross direction) and two pluralities of strands 34, 36 that both
extend at an angle with respect to strands 30 and are oriented at
opposite angles with respect to each other so they intersect with
each other in an X-like pattern 38. Pluralities of strands 34, 36
may be interwoven with strands 30, 32 and each other so as to form
a strongly woven scrim material having high strength and low
elongation.
[0037] In another embodiment, the impact resistant layer may have a
triaxial weave pattern in which a first plurality of substantially
parallel strands extend in the longitudinal direction of the sheet
material, a second plurality of substantially parallel strands
extend at an angle with respect to the first plurality of strands
that is between 45 and 85 degrees, and a third plurality of
substantially parallel strands extend at an angle with respect to
the first plurality of strands that is between 95 and 135 degrees.
The second and third pluralities of strands typically extend at
opposite angles with respect to each other so that the strands
intersect each other to form an X-like pattern.
[0038] In yet another embodiment, the impact resistant layer
comprises a first plurality of substantially parallel strands that
extend in the longitudinal direction of the sheet material, a
second plurality of substantially parallel strands and a third
plurality of substantially parallel strands that extend at opposite
angles with respect to each other and intersect each other to form
an X-like pattern. In one embodiment, the second plurality of
strands extends at an angle with respect to the first plurality of
strands that is between 75 and 85 degrees, and a third plurality of
substantially parallel strands extend at an angle with respect to
the first plurality of strands that is between 95 and 105 degrees.
In some embodiments, the impact resistant layer may include a
second set of intersecting strands that extend at different angles
with respect to the first plurality of strands than the second and
third plurality of strands to thereby define an impact resistant
layer having two X-like patterns of strands that are of different
size with respect to each other.
[0039] Other weaving patterns or numbers of strands may be employed
in the practice of the invention provided the resulting impact
resistant layer has sufficient impact resistance so that a wall
structure employing the impact resistant sheet material is capable
of passing the Miami-Dade County Large Missile Impact Test. The
number of strands per square inch may range from about 5 to 50
strands per square inch, such as from 5 to 40, 5 to 30, and 10 to
25 strands per square inch. For example, in the embodiment
illustrated in FIGS. 3 and 4, the numbers of strands per square
inch may range from about 10 to 30, and desirably from about 15 to
25, and more desirably from about 17-20. In the embodiment
illustrated in FIG. 5, the number of strands per square inch may
range from about 5 to 20, and in particular from about 5 to 15, and
more particularly, from about 7 to 10 strands per square inch. The
strands generally have a denier between about 500 and 1,500, with a
denier of about 800 to 1,200 being somewhat more preferred.
[0040] In order to provide the desired impact resistance, it is
generally important that the strands comprising the impact
resistant layer, and hence the impact resistant layer itself, have
low elongation and high tenacity. Generally, it is desirable that
the impact resistant layer has low elongation in the cross and/or
machine directions so that elongation of the impact resistant layer
is maintained at a minimum level during an impact. For example, in
some cases having a higher level of elongation may permit an object
impacting the impact resistant sheet material to pass through, or
at least partially through, a building structure before the impact
resistant layer is able to sufficiently retard the object's forward
movement. It may also be desirable that the impact resistant layer
has at least some elongation in the machine and cross directions so
that upon being impacted by an object moving at a relatively high
rate of speed, the impact resistant layer has some slight give due
to the impact. This slight give (elongation) allows energy from the
impact to be distributed into the surrounding regions of the impact
resistant layer so that the total force of the impact is not
localized only at the site of impact. As a result, impact energies
can be distributed into surrounding regions of the impact resistant
layer, which may help prevent breakage of the impact resistant
layer.
[0041] Generally, the desired amount of elongation will depend on
the tenacity and number of strands in the area of impact. For
example, strands having a relatively higher tenacity are able to
absorb greater impacts than strands having a lower tenacity. In one
embodiment, the impact resistant layer has an elongation that is at
least 1%, and preferably greater than 2%, 3%, 4%, 5% or more. In
one particular embodiment, the impact resistant layer has an
elongation in the machine and cross directions that is between
about 2 and 20%, and desirably between 5 and 15%, and more
desirably between 5 and 12%. In one embodiment, the impact
resistant layer has an elongation that is between about 6 and 10%,
such as from about 8 to 10%. In one embodiment, the impact
resistant layer has an elongation that is less than 20%, and in
particular less than 10%.
[0042] The impact resistant layer has a tensile strength that is
generally from about 445 to 1800 Newtons (N). In one particular
embodiment, the impact resistant layer has a tensile strength that
is from about 500 to 1500 N, 600 to 1200 N, or from about 800 to
1,000 N. In some embodiments, the impact resistant layer has a
tensile strength that is from about 600 to 1,800, 1,000 to 1,800 N
and from about 1,200 to 1,600 N. Percent elongation and tensile
strength are measured in accordance with the test procedures
described below under the section entitled "Test Methods."
[0043] The strands comprising the impact resistant layer can
comprise a variety of different materials, such as nylon,
polyester, fiberglass, cut resistant fibers, such as aramids
including Kevlar.RTM., and combinations thereof. Suitable
polyesters may include polyethylene terephthalate,
polytrimethylene, terephthalate, and polytributylene terephthalate.
In one embodiment, the impact resistant layer comprises a
combination of fiberglass strands and polyethylene terephthalate
strands. For example, the impact resistant layer may include from
about 50 to 95 wt % of fiberglass strands and from about 5 to 45 wt
% polyethylene terephthalate strands. In some embodiments, the
impact resistant layer may desirably comprise about 60 to 90 wt. %
fiberglass strands and from about 10 to 40 wt. % polyethylene
terephthalate strands, and more desirably from about 75 to 85 wt. %
fiberglass strands, and from about 15 to 25 wt. % polyethylene
terephthalate strands. Suitable materials for the impact resistant
layer include scrim materials available from Milliken Co., and
Saint Gobain.
[0044] The impact resistant layer 20 and the barrier layer 22 are
preferably bonded, adhered or laminated together to form a single
composite. Preferably, the impact resistant layer 20 has a strong
adherence to the barrier layer 22 and/or fibrous substrate 24. As
discussed in greater detail below, typical bonding and lamination
procedures may include those that involve adhering the impact
resistant layer and barrier layer together with or without an
adhesive, or using heat, pressure or both to combine these
materials. In one embodiment, the impact resistant layer 20 and the
barrier layer 22 can be attached to each other with thermal
bonding, adhesive bonding, and the like. The resulting impact
resistant sheet material generally has a thickness of about 10 to
60 mils, and in particular, from about 20 to 50 mils, and more
particularly, about 30 to 35 mils.
[0045] As noted above, the barrier layer 22 may comprise a fibrous
substrate that is moisture vapor permeable and substantially liquid
impermeable. In this regard, FIG. 3 illustrates an embodiment of
the invention in which the barrier layer 22 comprises a fibrous
nonwoven sheet material comprising a plurality of filaments and/or
fibers that are thermally bonded to each other to form a strong and
coherent web. In one embodiment, the barrier layer 22 may comprise
a spunbond nonwoven web comprising flash-spun polyethylene
plexifilamentary fibers that are thermally bonded to one another.
An example of one such barrier fabric is Tyvek.RTM., which is
available from E.I. du Pont de Nemours and Company of Wilmington,
Del. ("DuPont"). In one particular embodiment, the fibrous
substrate comprises a spunbond nonwoven that is formed of
substantially continuous polypropylene filaments, and is
commercially available from Fiberweb.TM. and sold under the
trademark Typar.RTM. or Tekton.RTM..
[0046] Suitable materials for the fibrous substrate 24 may include
a nonwoven, woven, or extruded webs. Suitable webs may include
spunbond webs, woven slit films, carded webs, meltblown webs,
flashspun webs, and the like. In a preferred embodiment, the
fibrous substrate comprises a nonwoven web, such as spunbonded and
centrifugally spun fabrics, and fabrics comprising discontinuous or
staple fibers, such as carded staple fiber webs, needlepunched
nonwovens, hydroentangled webs and the like. Melt blown webs of
continuous or discontinuous fibers also may be suitable. In one
embodiment, the fibrous substrate comprises a high tenacity
nonwoven fabric formed from polymeric fibers which are randomly
disposed and bonded to one another to form a strong nonwoven web.
Generally, 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
housewrap. In one particular embodiment, the fibrous substrate
comprises a spunbond nonwoven that is formed of substantially
continuous polypropylene filaments. Such a nonwoven is commercially
available from Fiberweb of Old Hickory, TN and sold under the
trademark Typar.RTM.Housewrap or Tekton.RTM.Housewrap.
[0047] With reference to FIGS. 4 and 5, embodiments of the
invention are illustrated in which the barrier layer 22 comprises a
fibrous substrate 24 to which a breathable, substantially liquid
impermeable coating layer 26, such as a film layer has been
adhered.
[0048] Preferably, the film layer 26 has a strong adherence to the
fibrous substrate 24, such that the film layer and the substrate
are not subject to delamination but instead are structurally
combined with one another to form a composite material. Generally,
the peel adhesion of the film layer 26 to the fibrous substrate 24
is at least 59 g/cm (150 grams/inch), and preferably at least 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. Adhesion of the film to the substrate is
measured in accordance with the test procedure described below
under the section entitled "Test Methods."
[0049] The thermoplastic polymer fibers or filaments comprising the
fibrous substrate 24 may 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 of the fibers or
filaments may also contain a pigment to render the fibrous
substrate opaque. In one particular embodiment, the fibers can be
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.
[0050] The fibrous substrate 24 generally has a basis weight of at
least 40 g/m.sup.2, such as 50 g/m.sup.2 or greater. In some
embodiments, the fibrous substrate may have a basis weight that is
from about 60 to 140 g/m.sup.2, and for certain embodiments, a
basis weight of from 80 to 110 g/m.sup.2.
[0051] In one embodiment, the fibrous substrate has a grab tensile
strength of at least 178 Newtons (40 pounds) in at least one of the
machine direction (MD) or the cross-machine direction (CD). More
preferably, the nonwoven substrate has a grab tensile strength of
at least 267 N (60 pounds) in at least one of the MD and the CD.
High tenacity and low elongation can be 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. In this
particular embodiment, 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. Mechanically drawing the
fibers may allow 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.
[0052] In one embodiment, the film layer 26 of the impact resistant
sheet material 10 is a moisture vapor permeable and substantially
liquid impermeable polymeric film. Suitable materials for the film
layer 26 may include breathable polymeric films that are inherently
permeable to moisture vapor, such as a monolithic film, or
microporous films. The film can comprise a preformed film that is
laminated to the fibrous substrate, or may comprise a film that is
coextruded onto the fibrous substrate. Generally, the film layer
can have a gauge or a thickness between about 0.25 and 20 mils and,
in particular from 0.25 mils, and more particularly from about 1 to
5 mils. The film layer may be applied to the fibrous substrate at a
minimum basis weight of 25 g/m.sup.2, and most desirably, from 30
to 50 g/m.sup.2.
[0053] In the case of a microporous film, the microporous film
layer may be rendered microporous, and hence breathable, by
mechanically stretching the film to create microporous openings
therein, or by using oils, additives, contaminants, and the like
that create a breathable material via phase separation within the
film. Methods of mechanically stretching the film include passing
the film through a pair of embossing rollers or passing film
through one or more intermeshing rollers that incrementally stretch
the film and thereby create microporous openings in the film at the
points of stretching. The microporous film can also be mechanically
stretched by passing the film over a series of rollers in which a
downstream roll is driven at a greater rate of speed than an
upstream roll.
[0054] Suitable polymeric materials for the film layer include
nylons, polyvinyl chloride (PVC), polyvinyl alcohol (PVA),
polyolefins, such as polyethylene, polypropylene, metallocenes, and
blends thereof, as well as blends of polyolefins with other
polymers. In a preferred embodiment, the composition from which the
film layer 26 is formed is prepared by blending or compounding one
or more thermoplastic polymers with suitable inorganic or organic
pore-forming fillers and with suitable additives, stabilizers and
antioxidants.
[0055] In one particular embodiment, the film layer 26 comprises a
polymer composition that includes at least one polyolefin polymer
component, such as polypropylene, propylene copolymers,
homopolymers or copolymers of ethylene, and copolymers such as
ethylene vinylacetate (EVA), ethylene methyl acrylate (EMA) and
ethylene acrylic acid (EAA), or blends of such polyolefins. The
polymer composition may, for example, comprise 100% polypropylene
homopolymer, or blends of polypropylene and polyethylene. Suitable
polyethylenes include low density polyethylene, high density
polyethylene, linear low density polyethylene (LLDPE), and blends
thereof. The polymer composition may also include other nonolefin
polymers.
[0056] Preferably, the polymer composition is blended with a
pore-forming filler that helps render the film microporous upon
being mechanically stretched. Generally speaking, the filler
material may be any mechanical pore-forming agent that does not
adversely affect the properties of the present invention. Fillers
that may be used in connection with the present invention include
inorganic or organic materials. Examples of the inorganic and
organic fillers include calcium carbonate, talc, clay, kaolin,
silica, diatomaceous earth, magnesium carbonate, barium to
carbonate, magnesium sulfate, barium sulfate, calcium sulfate,
aluminum hydroxide, zinc oxide, magnesium hydroxide, calcium oxide,
magnesium oxide, titanium dioxide, alumina, mica, glass powder,
zeolite, silica clay, acetyl salicylic acid, molecular sieves, ion
exchange resins, wood pulp, pulp powder, ferrous hydroxide, borox,
soda line, alkaline earth metals, baking soda, activated alumina,
etc. Calcium carbonate is particularly preferred for low cost,
whiteness, inertness, and availability. Calcium carbonate is
particularly preferred as a pore-forming filler, and it is
preferred that the calcium carbonate be treated with calcium
stearate to render it hydrophobic and to prevent agglomeration or
clumping. Preferably, the pore-forming filler has a particle size
of no more than about 5 microns.
[0057] To achieve the high level of MVTR required for barrier
applications, such as a housewrap, it is preferred that the polymer
and pore-forming filler blend comprise at least 20% by weight
filler, and desirably 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, hindered amine light stabilizer compounds,
ultraviolet absorbers, antioxidants and antimicrobials.
[0058] In one embodiment, the film layer 26 is extruded and
laminated directly onto the fibrous substrate 24 in a single
process. For example, the film-forming polymer composition is
heated and mixed in an extruder, and is extruded from a slot die to
form a molten polymer film. The molten polymer film is brought
directly into contact with the fibrous substrate 24 and the molten
film composition is forced into intimate engagement with the
fibrous web by directing the materials through a nip defined by a
pair of cooperating rotating rolls formed between a metal roll and
a rubber roll. The fibrous substrate layer may be provided as a
web, for example supplied from a roll, and the film layer and the
barrier layer comprising the combination of the fibrous substrate
and film layer are passed through the nip of the rolls to adhere
the film layer to the surface of the fibrous substrate. The barrier
layer thus formed can then be subjected to stretching to render the
film layer microporous.
[0059] As noted above, various stretching techniques can be
employed to develop the micropores in the impact resistant 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. In one embodiment, the barrier layer (i.e., the
combination of the fibrous substrate and film layers) is
incrementally stretched to a permanent elongation less than about
5%. The barrier layer can be incrementally stretched to a permanent
elongation less than about 2%, more specifically less than about
1%. Alternatively, the barrier layer can be incrementally stretched
without any permanent elongation of the material.
[0060] In a preferred embodiment, the barrier layer 22 comprises a
spunbond nonwoven that is formed of substantially continuous
polypropylene filaments to which a polymeric film comprising
polypropylene and about 40 to 50 weight % filler is
extrusion-coated. Examples of such composites for the barrier layer
are described in commonly assigned, copending U.S. Patent
Publication No. 2004/0029469, the content of which is hereby
incorporated by reference.
[0061] After depositing the film layer on the fibrous substrate,
the resulting barrier layer 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. After stretching, the impact resistant
layer can be adhered to a surface of the fibrous substrate opposite
the film layer. As discussed above, the impact resistant layer can
be adhesively adhered to the fibrous substrate. In some
embodiments, the adhesive is applied only to the strands comprising
the impact resistant layer so that the fibrous substrate and impact
resistant layer are only bonded to each other at points of contact.
This may be particularly useful in embodiments in which the
adhesive has a lower than desired moisture vapor transmission rate.
In this regard, FIG. 6 is a cross-sectional side view of the impact
resistant sheet material 10 taken along line 6-6 of FIG. 4. As
shown, an adhesive material 40 is located between the impact
resistant layer 20 and the fibrous substrate 24 at points of
contact between the two layers. In applications where it is
desirable for the impact resistant sheet material to have
breathability, the adhesive may be limited to only points of
contact so that the surface of the fibrous substrate has sufficient
surface area so that a desired level of breathability is
maintained. In other embodiments, it may be desirable to select a
breathable adhesive so that application of the adhesive does not
adversely affect the breathability of the impact resistant sheet
material.
[0062] Alternatively, the adhesive can be broadly applied to the
fibrous substrate, such as a coating. In embodiments where the
adhesive is applied as a coating, it may be desirable to select and
an adhesive that does not adversely affect the breathability of the
impact resistant sheet material. It should be understood that
adhesives having low MVTRs can be used in applications where
breathability is not a concern.
[0063] A wide variety of adhesives can be used in the practice of
the invention, which may include hot melt adhesives, pressure
sensitive adhesives, UV cured adhesives, water-based adhesives, and
the like In some embodiments, the adhesive may also include
additional agents such as fire retardants, UV stabilizers, and the
like.
[0064] The impact resistant sheet material can be subjected to heat
in order to dry the adhesive layer and thereby securely adhere the
fibrous substrate to the impact resistant layer. In some cases,
heating of the impact resistant layer can result in shrinkage of
the film layer, which can in turn result in shrinkage of the
microporous openings. Accordingly, care should be given in
selecting the temperature for drying the adhesive layer. In some
embodiments, it may be desirable to pre-stretch the barrier layer
(i.e., the combination of the film and fibrous substrate) prior to
attaching the impact resistant layer. Pre-stretching increases the
size of the microporous openings so that if shrinkage does occur,
the microporous openings will still remain open and the
breathibility of the film layer will not be adversely affected. For
example, the barrier layer can be pre-stretched so that its
breathability is increased by up to 1, 2, 3, 4, or 5% prior to
attachment of the impact resistant layer.
[0065] From the foregoing discussion, it should be apparent that
the impact resistant sheet material of the present inventions can
be used in a variety of different construction applications, such
as housewrap materials, flashing, roofing underlayment, and the
like. In some embodiments, the impact resistant sheet material can
also be used to protect objects such as trailers, boats,
automobiles, and the like from impacts with wind-borne debris.
[0066] The impact resistant sheet material can be mounted on the
exterior sheathing of a walls structure in the same way
conventional housewrap sheet material is applied. For example, the
impact resistant sheet material can be incorporated into a wall
structure comprising a plurality of framing members, such as
"2.times.4" studs, to which an exterior sheathing, such as oriented
strand board (OSB), plywood, or gypsum board has been attached. The
sheathing can comprise a fiber insulation board formed from one or
more of mineral fibers such as glass fibers, rock wool fibers, slag
fibers, organic fibers, ceramic fibers (e.g., alumina), silica or
basalt fibers that are resin bonded into a rigid or semi-rigid
board. The impact resistant sheet material can be secured to the
sheathing with a variety of different fasteners, such as staples,
nails, and the like. The walls structure typically includes an
outer cladding that is provided on the exterior side of the impact
resistant sheet material. The cladding can be concrete masonry,
ceramic tiles, glass, treated wood panel, siding, fiber cement
weather board, shingles, bricks, stucco or stone, or the like.
[0067] FIG. 7 illustrates another possible application for the
impact resistant sheet material. In this embodiment, instead of
being applied to the exterior sheathing of a completed building
like a housewrap material, the impact resistant sheet material
forms part of a composite panel 44 comprising a substrate 46 to
which the impact resistant sheet material 10 has been attached.
Substrate 46 can comprise a sheathing material such as oriented
strand board (OSB), plywood, gypsum board, and the like. In some
embodiments, substrate 46 can comprise an insulating material such
as a mineral fiber material, including mineral fiber board,
polystyrene or other foam materials. The impact resistant sheet
material can be attached to the substrate with fasteners,
adhesives, and the like. In some embodiments, the impact resistant
sheet material is laminated to the substrate. In one embodiment, a
plurality of composite panels 44 can be used to envelop a building
structure and thereby provide an exterior wall structure having
moisture and air barrier properties as well as impact
resistance.
[0068] In additional embodiments, the impact resistant sheet
material of the present invention can also be used advantageously
in the construction of so called "safe rooms" that can be used to
protect specific interior rooms or areas of buildings from objects
moving at relatively high rates of speed, such as wind-borne
debris. In this regard, FIG. 8 illustrates a building 12 having an
interior room 50 with a plurality of walls 52 to which the impact
resistant sheet material 10 has been applied. During a wind storm,
occupants of the building 12 can seek shelter in safe room 50 from
wind borne debris. Preferably, safe room 50 is located within the
interior of the building that is spaced apart from the exterior
walls of the building,
[0069] In embodiments wherein the impact resistant sheet material
is utilized to protect interior rooms, such as discussed above, the
impact resistant sheet material does not necessarily have moisture
barrier properties. For example, in this embodiment the impact
resistant material may include both the impact resistant layer and
the fibrous substrate, and in some cases might not include a layer
that could be considered a moisture barrier layer. Suitable
materials for the impact resistant layer and the fibrous substrate
include those discussed above.
[0070] In some embodiments, the impact resistant sheet material may
lack barrier properties. For example, in one embodiment, the impact
resistant sheet material may comprise the impact resistant layer
that is attached to a relatively open fibrous substrate.
Test Methods
[0071] 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.
[0072] The following tests are hereby incorporated by
reference.
[0073] 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).
[0074] 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.
[0075] Percent Elongation is a measure of the maximum elongation of
a fabric at failure when subjected to unidirectional stress.
Percent Elongation is determined according to ASTM D 5034-95.
[0076] 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 4632--Standard Test Method
for Grab Breaking Load and Elongation of Geotextiles, 1991
(reapproved 1996).
[0077] 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.
[0078] 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.
[0079] Impact Resistance Free-Falling Dart Method is a measure of
the weight required to cause 50% of tested films to failure by
impact from a falling dart under specified test conditions. Impact
resistant Free-Falling Dart measurements are determined in
accordance with ASTM D-1709, Method B2.
[0080] Miami-Dade County Large Missile Impact Test (Miami-Dade
Protocolsl PA 201, PA 202, and PA 203). Under this test the wall
structure is impacted with a two-by-four (2''.times.4'') board
weighing 9 lbs. and traveling at approximately 34 mph. To
successfully past the test, at least three separate impacts are
conducted and the wall structure must prevent the board from both
penetrating the wall structure or creating a significant
opening.
[0081] Moisture Vapor Transmission Rate (MVTR) is determined by
ASTM E 96, Standard Test Methods for Water Vapor Transmission of
Materials; 1995, Procedure A.
[0082] Mullen burst strength is determined by ASTM D-3786, Standard
Test Method for Hydraulic Bursting Strength of Textile
Fabrics--Diaphragm Bursting Strength Tester Method.
[0083] Peel Strength is measured in accordance with ASTM D
2724.
[0084] Puncture strength is measured according to ASTM
D-4833-88.
[0085] Tear Strength is measured in accordance with ASTM D 4533
(trapezoidal tear), tensile strength measurements are determined
according to ASTM D 5034-95.
Example 1
[0086] Typar.RTM. 3201, a spunbonded polypropylene nonwoven fabric
produced by Fiberweb of Old Hickory, Tenn., was used as the fibrous
nonwoven substrate for producing a high MVTR extrusion coated
composite sheet material. Typar.RTM. 3201 is a spunbond
polypropylene nonwoven fabric having a basis weight of 64
g/m.sup.2, a thickness of 0.229 mm (9 mils), an MD grab tensile
strength of 360 N (81 lbs.), a CD grab tensile strength of 329 N
(74 lbs.), a trapezoidal tear strength of 165 N (37 lbs.) in the MD
and 151 N (34 lbs.) in the CD, and a Mullen burst strength of
379211 Pascal (55 psi.). This substrate was extrusion-coated with a
polypropylene polymer composition containing about 50 percent by
weight calcium carbonate filler. The polymer film was extruded onto
the substrate at a basis weight of 30 g/m.sup.2. The resulting
composite was incrementally stretched in the CD.
[0087] After being incrementally stretched, the combination of the
nonwoven substrate and polymer film was stretched in the cross
direction to increase its breathability by about 5% percent. A
scrim layer (i.e., impact resistant layer) was then adhesively
bonded to the surface of the fibrous substrate opposite the film
layer. In this step, a water soluble adhesive was applied to the
scrim layer. The scrim layer comprised a combination of fiber glass
and polyethylene terepthalate strands, available from Milliken Co.
The amount of adhesive applied was about 50 weight percent, based
on the total weight of the scrim layer. The resulting sheet
material was passed over a series of dryer cans to evaporate any
excess water out of the sheet material. The drying step was
performed at a temperature of about 100-110.degree. C. Various
properties of the resulting impact resistant sheet material are
provided below.
TABLE-US-00001 TABLE 1 Properties of the Impact resistant Sheet
Material Property Test method Units Value Hydrohead AATCC 127 cm
550 MVTR ASTM E 96-A g/m.sup.2/day 60 Peel Strength ASTM D 2724
Lbs. 2.94 MD Tensile Strength ASTM D 4632 Lbs./inch 233 MD
Elongation ASTM D 4632 % 8.7 CD Tensile Strength ASTM D 4632
Lbs./inch 191 CD Elongation ASTM D 4632 % 6.9 Thickness ASTM D 1777
mils 21.3 Basis Weight ASTM D 3776 osy 7.6
[0088] The impact resistant sheet material also had a flame spread
index of 25 and a smoke developed index of 200, as measured in
accordance with ASTM E 84; a self-ignition temperature of
788.degree. F., as measured in accordance with ASTM D 1929; and a
burning rate of 54 mm/min as measured in accordance with ASTM D
635.
[0089] The impact resistance of the impact resistant sheet material
of Example 1 was compared to various barrier sheet materials. The
results are summarized in Table 2 below. The Samples described in
Table 2 are as follows:
[0090] Sample 1: Inventive impact resistant sheet material
described in Example 1, above.
[0091] Sample 2: Tyvek.RTM. Homewrap.RTM. available from Du Pont de
Nemours and Company;
[0092] Sample 3: Woven slit film available from Lowes Product No.
LW1490LOW, white 9'.times.150' rolls;
[0093] Sample 4: Breathable sheet material comprising a spunbond
polypropylene substrate and an outer breathable, monolithic film
layer, available from Fortifiber, under the trademark
Weathersmart.TM.;
[0094] Sample 5: R-Wrap produced by Covalence Coated Products
(formerly Ludlow Coated Products).
TABLE-US-00002 TABLE 2 Impact Properties of Inventive Sheet
Material vs. Various Barrier Sheet Materials Test Sample 1 Sample 2
Sample 3 Sample 4 Sample 5 Test Method Free Falling Dart 2.27
<0.70 0.83 <0.70 -- ASTM D 1709-4 Impact Failure Weight
(1bs.) (method B 2'' dart @ 60'') Average Thickness (mm) 0.669
0.076 0.108 0.265 -- ASTM D 1777-75 Probe Penetration (psi) 4,132
1,604 2532 948 1,749 ASTM D 4833-88 Mullen Burst 500* 103 123 51 91
ASTM 3786-87 *Maximum test equipment pressure 500 psi - sample
exceeded equipment capability. **<0.70 = minimum weight for the
impact head with no additional weights is 0.70 lbs.
[0095] The Impact resistant sheet material of the present invention
was also tested according to the Miami-Dade County Large Missile
Impact Test. To pass the Miami-Dade County Large Missile Impact
Test, the impact resistant material was tested according to the
following tests:
[0096] Air infiltration in accordance with Testing Application
Standard (TAS) 202-94 (ASTM E 283-04);
[0097] Water Resistance tests in accordance with TAS 202-94 (ASTM E
331-00);
[0098] Structural Performance test in accordance with TAS 202-94
(ASTM E 330-02);
[0099] Impact Resistance in accordance with TAS 201-94; and
[0100] Cyclic tests in accordance with TAS 203-94, the contents of
which are all hereby incorporated by reference.
[0101] In accordance with the Miami-Dade County Large Impact
Missile Test, two wall panels comprising the impact resistant sheet
material of Example 1 were constructed according to the following
specifications and the wall 60 illustrated in FIG. 9.
[0102] Wall Panel 1
[0103] Interior wall (62): 1.2'' Drywall fastened to studs (66)
with 11/4'' self-tapping screws at each end, 8'' on center;
[0104] Studs (66): 31/2'', 18 gauge steel, 24'' on center;
[0105] Stud Cavities (67): R-13, 31/2'' Kraft faced fiberglass
insulation (not shown);
[0106] Exterior sheathing (72): 5/8'' DensGlass Gold fastened to
studs 66 with 11/4'' self-tapping screws at each end, 8'' on
center;
[0107] Exterior housewrap (10): Impact resistant sheet material of
Example 1, fastened to studs with 11/4'' self-tapping 1'' plastic
cap screws, 16'' on center;
[0108] Metal Lath (68): 33.2 self-furring galvanized, 96.times.24''
sheets mounted horizontally with a 4' overlap, fastened with 11/4''
S 12 screws 6'';
[0109] Exterior stucco (70) 3-layers: 1) scratch coat: mixture of
sto powder wall stucco and 200# mason sand, approximately 1/3''
thick, notch troweled; 2) brown coat: applied with sto powder and
mason sand 3/4'' thick, then rodded off smooth; and 3) finish coat:
mixture of 50 lb. bag of Ivory autoclaved lime, 1/2 bag (46.3 lbs)
of Portland cement, 11/2 bags (150 lbs) of 30/40 silica.
[0110] Wall Panel 2
[0111] Wall Panel 2 was constructed similarly to Wall Panel 1, with
the exception that the Wall Sample 2 included the following
additional components:
[0112] Exterior Foam Board disposed adjacent to the impact
resistant layer, the foam board comprised a
2'.times.4'.times.11/2'' polystyrene bead board fastened to studs
with 3'' Windlock wind Devil II fasteners-9/board. Each fastener
was spotted with primas MD (Dryvit). The exterior of the Wall Panel
2 comprised an exterior base coat of Dryvit Primas MD with a layer
of Dryvit 40 oz mesh embedded, and a Finish Coat comprised of
Dryvit finish with Dryvit medium base sand pebbles.
[0113] The impact resistance of Wall Samples 1 and 2 was tested in
accordance with Testing Application Standard (TAS) 201-94, the
content of which is hereby incorporated by reference. In accordance
with 6.3.2.1 Large Missile, the impact resistant test was carried
out with a missile projectile that comprised a solid S4S nominal
2.times.4 #2 surface dry southern Pine. The weight of the Missile
was 9 lbs, and had a length of at 7 feet. The missile was fired at
various locations on each of the wall panels at a speed of 34 mph
as specified in Tables 4 and 7 below. A specimen is considered to
fail if the impact results in a change in condition of the specimen
indicative of deterioration under repeated load or incipient
failure, such as cracking, fastener loosening, local yielding, or
loss of adhesive bond.
[0114] Upon successfully passing TAS 201-94, Wall Panels 1 and 2
were tested under a cyclic wind pressure loading in accordance with
TAS 203-94, the content of which is hereby incorporated by
reference. In accordance with this test, Wall Panels 1 and 2 were
subjected to a positive and negative load to create inward and
outward loading on the wall panels. Successful specimens have no
resultant failure or distress and shall have a recovery of at least
90% over maximum deflection. The results of the testing are
summarized in the Tables below.
[0115] Three specimens for each of Wall Panels 1 and 2 were tested.
The results for Wall Panel 1 are summarized in Tables 3-5
below.
TABLE-US-00003 TABLE 3 TAS202 TEST RESULTS WALL PANEL 1 (+/-30 psf
design pressure) ASTM Deflection Deflection Test Load Deflection
Center Bottom Load Test Method Lbs/ft.sup.2 Top (in.) Span (in)
(in) Results Duration Air Infiltration E283 1.57 N/A N/A N/A BDL*
N/A Scfm/ft.sup.2 Preload (Pos.) E330 +22.5 0.071'' 0.103'' 0.033''
Pass 30 sec Preload Perm. Set 0 0.029'' 0.035'' 0.017 .sup. 0.012''
-- Design Load (Pos.) E330 +30 0.112'' 0.164'' 0.056'' Pass 30 sec
Design Load Perm Set 0 0.042'' 0.056'' 0.031'' 0.020'' -- Preload
(Neg.) E330 -22.5 0.180'' 0.183'' 0.051'' Pass 30 sec Preload Perm.
Set 0 0.031'' 0.080'' 0.023'' 0.053'' -- Design Load (Neg.) E330
-30 0.300'' 0.329'' 0.091'' Pass 30 sec Design Load Perm. Set 0
0.074'' 0.162'' 0.055'' 0.098'' -- Water Resistance E331 +4.5 N/A
N/A N/A Pass 15 min. Test Load (Pos.) E330 +4.5 0.126'' 0.299''
0.117'' Pass 30 sec Test Load Perm. Set 0 0.006'' 0.068'' 0.052''
0.039'' -- Test Load (Neg.) E330 -4.5 0.283'' 0.358'' 0.128'' Pass
30 sec Test Load Perm. Set 0 0.051'' 0.153'' 0.093'' 0.081'' --
Forced Entry TAS202 N/A N/A N/A N/A N/A N/A *Air infiltration was
below the detectable limits of the equipment used.
TABLE-US-00004 TABLE 4 TAS201 Large Missile Impact Test Results of
Wall Panel 1 Spec- imen Re- No. Impact Locations Speed Observations
marks #1 1 Lower Corner 50.1 Penetrated Stucco, Pass ft/sec slight
tear in wrap 2 Center of Wall Panel - 50.3 Penetrated Stucco, Pass
3'' from stud ft/sec slight tear in wrap #2 1 Center of Wall Panel
- 50.5 Penetrated Stucco, Pass 3'' from stud ft/sec slight tear in
wrap 2 Upper Corner 49.8 Penetrated Stucco, Pass ft/sec slight tear
in wrap #3 1 Lower Corner 50.2 Penetrated Stucco, Pass ft/sec
slight tear in wrap 2 Center of Wall Panel - 50.4 Penetrated
Stucco, Pass 3'' from stud ft/sec slight tear in wrap
TABLE-US-00005 TABLE 5 TAS203 Cycling Test Results Design Pressure:
+/-30 spf Pressure Specimen No. 1 Specimen No. 2 Specimen No. 3
Cycles (lbs/ft.sup.2) Def. Set Remarks Def. Set Remarks Def. Set
Remarks 600 0-15 N/A N/A Pass N/A N/A Pass N/A N/A Pass 70 0-18 N/A
N/A Pass N/A N/A Pass N/A N/A Pass 1 0-39 N/A N/A Pass N/A N/A Pass
N/A N/A Pass 600 0-15 N/A N/A Pass N/A N/A Pass N/A N/A Pass 70
0-18 N/A N/A Pass N/A N/A Pass N/A N/A Pass 1 0-39 N/A N/A Pass N/A
N/A Pass N/A N/A Pass
Test Results for Wall Panel 2
TABLE-US-00006 [0116] TABLE 6 TAS202 TEST RESULTS WALL PANEL 2
(+/-30 psf design pressure) ASTM Deflection Deflection Test Load
Deflection Center Bottom Load Test Method Lbs/ft.sup.2 Top (in.)
Span (in) (in) Results Duration Air Infiltration E283 1.57 N/A N/A
N/A BDL* N/A Scfm/ft.sup.2 Preload (Pos.) E330 +22.5 0.150''
0.230'' 0.072'' Pass 30 sec Preload Perm. Set 0 0.016'' 0.034''
0.023 .sup. 0.015'' -- Design Load (Pos.) E330 +30 0.185'' 0.325''
0.115'' Pass 30 sec Design Load Perm Set 0 0.026'' 0.060'' 0.052''
0.021'' -- Preload (Neg.) E330 -22.5 0.197'' 0.333'' 0.177'' Pass
30 sec Preload Perm. Set 0 0.033'' 0.108'' 0.110'' 0.037'' --
Design Load (Neg.) E330 -30 0.246'' 0.446'' 0.237'' Pass 30 sec
Design Load Perm. Set 0 0.051'' 0.147'' 0.144'' 0.050'' -- Water
Resistance E331 +4.5 N/A N/A N/A Pass 15 min. Test Load (Pos.) E330
+4.5 0.306'' 0.653'' 0.347'' Pass 30 sec Test Load Perm. Set 0
0.066'' 0.206'' 0.252'' 0.047'' -- Test Load (Neg.) E330 -4.5
0.269'' 0.680'' 0.424'' Pass 30 sec Test Load Perm. Set 0 0.060''
0.219'' 0.273'' 0.051'' -- Forced Entry TAS202 N/A N/A N/A N/A N/A
N/A *Air infiltration was below the detectable limits of the
equipment used.
TABLE-US-00007 TABLE 7 TAS201 Large Missile Impact Test Results
Wall Panel 2 Spec- imen Re- No. Impact Locations Speed Observations
marks #1 1 Lower Corner 50 Penetrated Stucco, Pass ft/sec slight
tear in wrap 2 Center of Wall Panel - 50 Penetrated Stucco, Pass
3'' from stud ft/sec slight tear in wrap #2 1 Upper Corner 50
Penetrated Stucco, Pass ft/sec slight tear in wrap 2 Center of Wall
Panel - 50 Penetrated Stucco, Pass 3'' from stud ft/sec slight tear
in wrap #3 1 Lower Corner 50 Penetrated Stucco, Pass ft/sec slight
tear in wrap 2 Center of Wall Panel - 50 Penetrated Stucco, Pass
3'' from stud ft/sec slight tear in wrap
TABLE-US-00008 TABLE 8 TAS203 Cycling Test Results Design Pressure:
+/-30 spf Pressure Specimen No. 1 Specimen No. 2 Specimen No. 3
Cycles (lbs/ft.sup.2) Def. Set Remarks Def. Set Remarks Def. Set
Remarks 600 0-15 N/A N/A Pass N/A N/A Pass N/A N/A Pass 70 0-18 N/A
N/A Pass N/A N/A Pass N/A N/A Pass 1 0-39 N/A N/A Pass N/A N/A Pass
N/A N/A Pass 600 0-15 N/A N/A Pass N/A N/A Pass N/A N/A Pass 70
0-18 N/A N/A Pass N/A N/A Pass N/A N/A Pass 1 0-39 N/A N/A Pass N/A
N/A Pass N/A N/A Pass
[0117] In addition to the wall structures above, wall samples were
tested in which the wall included an exterior surface comprising
vinyl siding and fiber cement board. The test results are
summarized in Table 9 below.
[0118] The wall structures were impacted by a 9 pound two-by-four
("2.times.4") traveling at 34 mph in accordance with Miami-Dade
County Large Missile Impact Test (TAS-201). Wall panels 3-10 were
not tested with cyclic wind pressure loading in accordance with TAS
203-94. The wall panels in accordance with the invention includes
the impact resistance sheet material of the present invention in
which
[0119] The following materials were used in the wall samples
described in Table 9 below:
[0120] Vinyl siding available from Georgia Pacific, product number
135-WH;
[0121] 1/2'' Styrofoam sheathing available from Dow under the
trademark Dow Styrofoam.TM., or foam boards available from Johns
Manville;
[0122] R-13 building insulation available from Johns Manville: JM
kraft based batts or unfaced batt;
[0123] DensGlass sheathing available from Georgia-Pacific under the
trademark DensGlass Gold.RTM.
[0124] Impact resistant sheet material is the same that used in
Wall Panels 1 and 2 discussed above.
TABLE-US-00009 TABLE 9 Panel Description (4-ft. .times. 8-ft.
Sample No. Wood Wall Stud Construction) Test Results Wall Panel 3
Vinyl Siding Failed (Comparative) 1/2 in. Dow Styrofoam sheathing
R-13 building insulation "2 .times. 4" wood studs 16'' on center
1/2 in. gypsum drywall. Wall Panel 4 Vinyl Siding Passed Impact
Resistant Sheet Material 1/2 in. Dow Styrofoam sheathing R-13
building insulation "2 .times. 4" wood studs 16'' on center 1/2 in.
gypsum drywall. Wall Panel 5 Vinyl Siding Failed (Comparative) 3/4
in. expanded polystyrene foam 5/8 in. GP DensGlass sheathing "2
.times. 4" wood studs 16'' on center R-13 building insulation 1/2
in. gypsum drywall. Wall Panel 6 Vinyl Siding Passed 3/4 in.
expanded polystyrene foam 5/8 in. GP DensGlass sheathing Impact
Resistant Sheet Material R-13 building insulation "2 .times. 4"
wood studs 16'' on center 1/2 in. gypsum drywall. Wall Panel 7
Vinyl Siding Passed 3/4 in. expanded polystyrene foam Impact
Resistant Sheet Material 5/8 in. GP DensGlass sheathing R-13
building insulation "2 .times. 4" wood studs 16'' on center 1/2 in.
gypsum drywall. Wall Panel 8 Vinyl Siding Failed (Comparative) 1/2
in. plywood sheathing R-13 building insulation "2 .times. 4" wood
studs 16'' on center 1/2 in. gypsum drywall. Wall Panel 9 Vinyl
Siding Passed Impact Resistant Sheet Material 1/2 in. plywood
sheathing R-13 building insulation "2 .times. 4" wood studs 16'' on
center 1/2 in. gypsum drywall. Wall Panel 10 Vinyl Siding Passed
1/2 in. plywood sheathing Impact Resistant Sheet Material R-13
building insulation "2 .times. 4" wood studs 16'' on center 1/2 in.
gypsum drywall. Wall Panel 11 Hardiplank .TM. fiber cement board
Passed Impact Resistant Sheet Material 5/8 in. GP DensGlass
sheathing R-13 building insulation "2 .times. 4" steel studs 16''
on center 1/2 in. gypsum drywall. Wall Panel 12 Hardiplank .TM.
fiber cement board Failed (Comparative) 5/8 in. GP DensGlass
sheathing R-13 building insulation "2 .times. 4" steel studs 16''
on center 1/2 in. gypsum drywall.
[0125] From the test results in Table 9, it can be observed that
the impact resistant sheet material of the present invention was
able to provide impact resistance to wall structures having vinyl
siding as an exterior covering.
[0126] Many modifications and other embodiments of the invention
set forth herein will come to mind to one skilled in the art to
which the invention pertains having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. Therefore, it is to be understood that the invention is
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.
* * * * *