Note: Descriptions are shown in the official language in which they were submitted.
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MECHANICALLY BONDED VISOR SYSTEM FOR SURGICAL HOOD
Related Application
The present application claims priority to U.S. Provisional Patent Application
No. 62/775,988, filed on December 6, 2018, the entire contents of which are
incorporated herein by reference.
Field of the Invention
The present invention relates to the visor component of surgical hoods that
can be used in conjunction with surgical gowns, helmets, and ventilation
systems
worn by medical care providers in the operating room or people in any other
environment where exposure to hazardous materials and liquids is a risk.
Background of the Invention
Surgeons and other healthcare providers often wear a combination of a
nonwoven-based surgical suit or gown, a hood with a visor, and an air cooling
or
ventilation system during operating procedures, particularly orthopedic total
joint
replacement surgeries such as arthroplasties and revisions of the knee, hip,
and
shoulder, in order to ensure sterile conditions in the operating room, protect
the
wearer, and create a comfortable environment for the wearer. During the course
of
such surgeries, aerosolized or droplets of biological fluid can spray onto the
visor,
obstructing the view of the surgeon or other healthcare provider. Thus, in
order to
provide surgeons and other healthcare providers with improved visibility, the
visor
can include one or more removable transparent films, where the surgeon or
other
healthcare provider can remove or peel away the transparent film should it
become
covered with biological fluids, tissue, etc., thus exposing a clean,
unobstructed
surface of an additional removable transparent film or the transparent base
film of
the visor positioned below the transparent film that was removed. The
transparent
films must be sterile, and because the transparent films are in close contact
with
each other, sterilization of the transparent films is often problematic.
Currently, ethylene oxide (EO) gas is used to sterilize all nonwoven-based
surgical suits or gowns and hoods. However, a problem exists when using EO gas
to sterilize visors with multiple transparent films, as the transparent films
are
typically in direct contact with each other, which prevents the EO gas from
penetrating through the outermost, exposed transparent film to sterilize the
underlying additional transparent films present.
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As such, a need exists for a visor design that allows for EO gas to be used to
sterilize a visor having a transparent base film and one or more transparent
removable films attached thereto in conjunction with the hood and/or surgical
suit or
gown with which it will be worn.
Summary of the Invention
In accordance with one particular embodiment of the present invention, a
visor system for a personal protection system is provided. The visor system
includes a base film and a first removable film mechanically bonded to an
outer-
facing surface of the base film via a first plurality of mechanical bond
points, where
gaps are present between adjacent mechanical bond points.
In another embodiment, the first removable film can include a tab, and the tab
can facilitate removal of the first removable film from the base film.
In still another embodiment, the base film and the first removable film can be
transparent.
In yet another embodiment, the base film can include a polyester or a
polycarbonate.
In an additional embodiment, the first removable film can include a polyester
or a polycarbonate.
In one more embodiment, the first plurality of mechanical bond points can be
ultrasonic bond points.
In another embodiment, the gaps can permit penetration of ethylene oxide
gas between the base film and the first removable film.
In still another embodiment, the base film can define a perimeter and the
first
removable film can define a perimeter, where the perimeter of the first
removable
film can be contained completely within the perimeter of the base film.
Further, the
first plurality of mechanical bond points can be located about the perimeter
of the
first removable film.
In yet another embodiment, the visor system can further include a second
removable film, where the second removable film can be mechanically bonded to
the first removable film via a second plurality of mechanical bond points,
where gaps
can be present between adjacent mechanical bond points.
In an additional embodiment, the second removable film can include a tab,
where the tab can facilitate removal of the second removable film from the
first
removable film.
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In one more embodiment, the second removable film can be transparent.
In another embodiment, the second removable film can include a polyester or
a polycarbonate.
In still another embodiment, the second plurality of mechanical bond points
can be ultrasonic bond points.
In yet another embodiment, the gaps can permit penetration of ethylene
oxide gas between the first removable film and the second removable film.
In an additional embodiment, the base film can define a perimeter and the
second removable film can define a perimeter, where the perimeter of the
second
removable film can be contained completely within the perimeter of the base
film.
Further, the second plurality of mechanical bond points can be located about
the
perimeter of the second removable film.
In one more embodiment, the visor system can be ethylene oxide gas
sterilized.
In accordance with another particular embodiment of the present invention, a
surgical hood comprising the visor system as described above is provided,
where
the surgical hood and the visor system are ethylene oxide gas sterilized.
In accordance one more embodiment of the present invention, surgical gown
comprising an integrated surgical hood and the visor system as described above
is
provided, where the surgical gown, the integrated surgical hood, and the visor
system are ethylene oxide gas sterilized.
A personal protection system including a surgical gown and a separate
surgical hood comprising the visor system as described above is also
contemplated
by the present invention, where the personal protection system is ethylene gas
sterilized in a single package.
These and other features, aspects and advantages of the present invention
will become better understood with reference to the following description and
appended claims. The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate embodiments of the
invention and,
together with the description, serve to explain the principles of the
invention.
Brief Description of the Figures
A full and enabling disclosure of the present invention to one skilled in the
art,
including the best mode thereof, is set forth more particularly in the
remainder of the
specification, including reference to the accompanying figures, in which:
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FIG. 1 illustrates a front view of a visor system according to one embodiment
of the present invention;
FIG. 2 illustrates a front view of another visor system according to one
embodiment of the present invention;
FIG. 3A illustrates a cross-sectional view of one of the removable films of
the
visor system of the present invention;
FIG. 3B illustrates a perspective view of the removable film of FIG. 3A;
FIG. 4A illustrates a cross-sectional view of the visor system of the present
invention where one removable film is mechanically bonded to a base film;
FIG. 4B illustrates a perspective view of the visor system of FIG. 4A;
FIG. 5A illustrates a cross-sectional view of the visor system of the present
invention where a first removable film is mechanically bonded to a base film
and a
second removable film is mechanically bonded to the first removable film;
FIG. 5B illustrates a perspective view of the visor system of FIG. 5A;
FIG. 6 illustrates a side view of a user wearing a personal protection and
ventilation system, including a disposable surgical gown, a hood with which
the visor
system of the present invention is integrated, and a helmet;
FIG. 7 illustrates a procedure for donning the disposable surgical gown and
hood with which the visor system of the present invention is integrated;
FIG. 8 illustrates various adjustment procedures that can be carried out while
using a personal protection and ventilation system that includes the visor
system of
the present invention.
FIG. 9 illustrates a personal protection and ventilation system with which the
visor system of the present invention can be used;
FIG. 10 illustrates a front view of one embodiment of a disposable surgical
gown with which the visor system of the present invention can be used;
FIG. 11 illustrates a rear view of one embodiment of the disposable surgical
of FIG. 10;
FIG. 12 illustrates a front view of another embodiment of a disposable
surgical gown with which the visor system of the present invention can be
used;
FIG. 13 illustrates a rear view of the disposable surgical gown of FIG. 12;
FIG. 14 illustrates a cross-sectional view of one embodiment of a first
material used in forming the front panel, sleeves, and hood of a disposable
surgical
gown with which the visor system of the present invention can be used; and
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FIG. 15 illustrates a cross-sectional view of one embodiment of a second
material used in forming the first rear panel and the second rear panel of a
disposable surgical gown with which the visor system of the present invention
can
be used.
5 FIG. 16 illustrates a front view of a visor system according to one
embodiment of the present invention.
FIG. 17 illustrates a front view of a visor system according to another
embodiment of the present invention.
FIG. 18 illustrates a front view of a visor system according to still another
embodiment of the present invention.
FIG. 19 illustrates a perspective view of a visor system according to one
embodiment of the present invention, where one layer of removable film is
being
removed from a base film.
FIG. 20 illustrates a zoomed in view of a visor system according to one
embodiment of the present invention showing one of the ultrasonic welding
sections
in detail.
FIG. 21 illustrates a zoomed in view of a visor system according to another
embodiment of the present invention showing one of the ultrasonic welding
sections
in detail.
FIG. 22 illustrates a zoomed in view of a visor system according to yet
another embodiment of the present invention showing one of the ultrasonic
welding
sections in detail.
Repeat use of reference characters in the present specification and
drawings is intended to represent the same or analogous features or elements
of
the present invention.
Definitions
As used herein, the term "spunbond" refers to fabric made from small
diameter fibers which are formed by extruding molten thermoplastic material as
filaments from a plurality of fine, usually circular capillaries of a
spinneret with the
.. diameter of the extruded filaments then being rapidly reduced as by, for
example, in
U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to
Dorschner et
at, U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and
3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartman, and U.S. Pat. No.
3,542,615 to Dobo et al. Spunbond fibers are generally not tacky when they are
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deposited onto a collecting surface. Spunbond fibers are generally continuous
and
have average diameters (from a sample of at least 10) larger than 7 microns,
more
particularly, between about 10 and 20 microns.
As used herein, the term "meltblown" refers to fabric formed by extruding a
molten thermoplastic material through a plurality of fine, usually circular,
die
capillaries as molten threads or filaments into converging high velocity,
usually hot,
gas (e.g. air) streams which attenuate the filaments of molten thermoplastic
material
to reduce their diameter, which may be to microfiber diameter. The meltblown
fibers
are then carried by the high velocity gas stream and are deposited on a
collecting
surface to form a web of randomly dispersed meltblown fibers. Such a process
is
disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin et al. Meltblown
fibers
are microfibers which may be continuous or discontinuous, are generally
smaller
than 10 microns in average diameter, and are generally tacky when deposited
onto
a collecting surface.
As used herein, the term "SMS laminate" refers to fabric laminates of
spunbond and meltblown fabrics, e.g., spunbond/meltblown/ spunbond laminates
as
disclosed in U.S. Pat. No. 4,041,203 to Brock et al., U.S. Pat. No. 5,169,706
to
Collier, et al, U.S. Pat. No. 5,145,727 to Potts et al., U.S. Pat. No.
5,178,931 to
Perkins et al. and U.S. Pat. No. 5,188,885 to Timmons et al. Such a laminate
may
be made by sequentially depositing onto a moving forming belt first a spunbond
fabric layer, then a meltblown fabric layer and last another spunbond layer
and then
bonding the laminate in a manner described below. Alternatively, the fabric
layers
may be made individually, collected in rolls, and combined in a separate
bonding
step. Such fabrics usually have a basis weight of from about 0.1 osy to 12 osy
(about 3.4 gsm to about 406 gsm), or more particularly from about 0.75 to
about 3
osy (about 25.4 gsm to about 101.7 gsm).
Detailed Description of Representative Embodiments
Reference now will be made in detail to various embodiments of the
invention, one or more examples of which are set forth below. Each example is
provided by way of explanation of the invention, not limitation of the
invention. In
fact, it will be apparent to those skilled in the art that various
modifications and
variations may be made in the present invention without departing from the
scope or
spirit of the invention. For instance, features illustrated or described as
part of one
embodiment, may be used on another embodiment to yield a still further
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embodiment. Thus, it is intended that the present invention covers such
modifications and variations as come within the scope of the appended claims
and
their equivalents.
Generally speaking, the present invention is directed to a visor system for a
surgical hood that can be a component of a personal protection system, which
can
include a ventilation system in some embodiments. The visor system includes a
transparent base film and one or more removable transparent films attached to
an
outer-facing surface of the transparent base film. The one or more removable
transparent films can be attached to the transparent base film and/or each
other by
mechanical bonding. In one particular embodiment, the type of mechanical
bonding
can be ultrasonic bonding. Specifically, a first removable transparent film
can be
attached to the base transparent film by mechanical bonding, and a second
removable transparent film can be attached to the first removable transparent
film
by mechanical bonding.
Further, to ensure that each of the transparent films and the base film are
able to be adequately sterilized by ethylene oxide (EO) gas, the transparent
films
are attached to each other via mechanical bond points (e.g., bond points
formed via
ultrasonic bonding) intermittently spaced around the perimeter of the
removable
transparent films. As such, a plurality of gaps can separate adjacent
mechanical
bond points to permit EO gas to penetrate each of the films to sterilize all
surfaces
of the films. Such an arrangement allows each underlying film of the visor
system
that is exposed after peeling away an outermost film and discarding the
outermost
film to be adequately sterilized by EO gas. Further, it is to be understood
that
because the transparent films of the present invention can be formed from
polycarbonate or polyester, which are materials through which EO gas cannot
penetrate, the plurality of gaps between the mechanical bond points required
by the
present invention are important to ensuring adequate sterilization by EO gas.
In
contrast, the use of an adhesive around the entire perimeter of the removable
transparent films to attach the removable transparent films to the base film
and/or
each other would not allow for EO gas penetration.
In other words, utilizing the mechanical bonding approach contemplated by
the visor system of the present invention allows sterilizing EO gas to
penetrate
between the transparent films, which is in stark contrast to current film
attachment
methods that utilize adhesives. Because ethylene oxide gas cannot penetrate
films
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bonded together via adhesives and cannot penetrate polyester and polycarbonate
transparent films, unlike the visor system of the present invention, currently
available visor systems often require the use of radiation sterilization
(e.g., gamma
radiation) as an interim step to sterilize the visor system separately before
the visor
system can be incorporated into a surgical hood, which is then sterilized by,
for
instance, EO gas, resulting in a very inefficient and time-consuming
sterilization
process.
On the other hand, the intermittently spaced mechanical bond points
contemplated by the present invention allow sufficient ethylene oxide gas
exposure
to kill biological indicator (BI) microbes to yield an underlying sterile
surface. The
resulting multi-layer visor system of the present invention can thus be formed
and
then bonded or otherwise attached to a surgical hood or a surgical gown with
attached hood, and the entire protective surgical garment can then be
sterilized in
one step via exposure to ethylene oxide gas, rather than having to sterilize
the
individual components in multiple steps as required for currently available
multi-layer
visor systems. This is because the gaps between the intermittent bond points
allow
the EO gas to penetrate the multiple films of the visor system during
sterilization.
This results in a surgical hood and/or gown where all of the transparent films
(e.g.,
the base film and one or more removable films) are sterile in the event that
one or
more of the outermost transparent films are peeled away from the visor system
and
discarded as they become soiled.
In addition, it is to be understood that the visor system of the present
invention contemplates placement of the intermittently spaced mechanical bond
points around the perimeter of the removable transparent films of the visor
system
so as to be unobtrusive to the surgeon or other healthcare provider. Moreover,
the
various transparent films are attached to each other with a bond strength
sufficient
to secure the transparent films to each other when in use, while also allowing
for the
surgeon or other healthcare provider to easily peel away and remove an
outermost
soiled transparent film without dislodging the other layers and the underlying
helmet
to which the surgical hood and visor system is secured.
As mentioned above, to create the mechanical bond points that are
intermittently spaced about the perimeter of the visor system of the present
invention, mechanical bonding in the form of ultrasonic bonding can be used.
Ultrasonic bonding utilizes ultrasonic energy, pressure, weld time, and hold
time
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parameters to melt polymeric films (e.g., polyester or polycarbonate
transparent
films). For instance, the mechanical bond points can be formed using an
ultrasonic
plunge welder such as a Branson ultrasonic plunge welder utilizing a power
supply
having a wattage of at least 2200 Watts, such as from about 2200 Watts to
about
.. 4000 Watts, such as from about 2600 Watts to about 3400 Watts. The weld
time
can range from about 0.04 seconds to about 0.12 seconds, such as from about
0.05
seconds to about 0.10 seconds, such as from about 0.06 seconds to about 0.08
seconds. Further, the hold time after welding can range from about 0.1 second
to
about 1 second, such as from about 0.2 seconds to about 0.8 seconds, such as
from about 0.4 seconds to about 0.6 seconds. In addition, the pressure applied
during welding can range from about 10 pounds per square inch (psi) to about
40
psi, such as from about 15 psi to about 35 psi, such as from about 20 psi to
about
30 psi.
Regardless of the specific welding parameters utilized, the resulting
mechanical (e.g., ultrasonically welded) bond points are intermittently spaced
apart
from each other about the perimeter of the removable transparent films in the
visor
system of the present invention so there is no continuous seal around the
perimeter
of the removable transparent films. Thus, the specific bond pattern
contemplated by
the present invention allows for EO gas penetration at the gaps located
between
each of the mechanical bond points and allows the gas to contact each of the
films'
surfaces to ensure adequate sterilization. Further, by locating the mechanical
bond
points on the outer perimeter of the transparent films of the visor system,
viewing is
not obscured, yet the transparent films are held securely in place until the
transparent films need to be peeled away from visor system. The various
features
of the visor system 180 of the present invention are discussed in more detail
with
references to FIGs. 1-8.
Turning first to FIG. 1, a front view of one visor system 180 contemplated by
the present invention is shown. The visor system 180 includes a base film 112
having a perimeter P1 and also having an outer-facing surface 270 that is
exposed
to the environment when incorporated into a surgical hood and an inner-facing
surface 272 (see FIGs. 4A-5B) that is the surface closest to a wearer's face
when
incorporated into a surgical hood. The base film 112 can include tabs Al and
A2
extending from a first side 266 and a second side 268 of the visor system 180.
Tabs Al and A2 can be used to secure the visor system 180 to a surgical hood,
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such as surgical hood 178 shown in FIGs. 6-8. The visor system 180 also
includes
at least one removable film 114 having a perimeter P2 that can be contained
completely within the perimeter P1 of the base film layer 112. In some
embodiments, the visor system 180 can include one or more additional removable
5 .. films, such as removable film 116. The removable films 114 and 116 can
each
include tabs (e.g., tabs B and C) that enable the wearer to peel-away the
outermost
removable film 114 or 116 when it becomes soiled or when the wearer's
visibility is
otherwise diminished due to the presence of blood, tissue, or other matter
coming
into contact with the film 114 or 116. As shown in FIG. 1, in some
embodiments, the
10 tabs B and C can both be present on the first side 266 of the visor
system 180.
Meanwhile, referring to FIG. 2, in other embodiments, the tabs B and C can be
on
opposing sides of the visor system 180. For instance, tab B, which is
associated
with the removable film 114, can be present on the first side 266 of the visor
system
180, while tab C, which is associated with the removable film 116, can be
present
on the second side 268 of the visor system 180.
The base film 112 can have a height H1 in the y-direction ranging from about
15 centimeters (cm) to about 35 cm, such as from about 17.5 cm to about 30 cm,
such as from about 20 cm to about 25 cm.
Meanwhile, the removable films 114 and 116 can have a height H2 in the y-
.. direction ranging from about 10 cm to about 30 cm, such as from about 12.5
cm to
about 25 cm, such as from about 15 cm to about 20 cm.
Further, the each of the tabs Al, A2, B, and C can have a height H3 in the y-
direction ranging from about 0.5 cm to about 3 cm, such as from about 0.75 cm
to
about 2.5 cm, such as from about 1 cm to about 2 cm.
In addition, the base film 112 can have an overall width W1 in the x-direction
including the width of the tabs Al and A2 ranging from about 35 cm to about 50
cm,
such as from about 37.5 cm to about 47.5 cm, such as from about 40 cm to about
45 cm, and a width W2 in the x-direction excluding the width of the tabs Al
and A2
ranging from about 32.5 cm to about 47.5 cm, such as from about 35 cm to about
45
.. cm, such as from about 37.5 cm to about 42.5 cm.
Moreover, the removable films 114 and 116 can have a width W3 in the x-
direction excluding the width of the tabs B and C ranging from about 25 cm to
about
42.5 cm, such as from about 27.5 cm to about 40 cm, such as from about 30 cm
to
about 37.5 cm.
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Additionally, the tabs Al, A2, B, and C can have a width W4 ranging from
about 0.5 cm to about 3 cm, such as from about 0.75 cm to about 2.75 cm, such
as
from about 1 cm to about 2 cm.
Further, regardless of the dimensions of each of the films 112, 114, and 116,
or the number of removable films present in the visor system 180, the films
can
each be transparent and can each be formed from polycarbonate or polyester. In
one particular embodiment, the films 112, 114, and 116 can be polyester.
Further,
the base film 112 can have a thickness in the z-direction ranging from about
150
micrometers to about 350 micrometers, such as from about 175 micrometers to
about 325 micrometers, such as from about 200 micrometers to about 300
micrometers, while the removable films 114 and 116 can each have a thickness
in
the z-direction ranging from about 10 micrometers to about 125 micrometers,
such
as from about 25 micrometers to about 100 micrometers, such as from about 50
micrometers to about 75 micrometers.
Turning now to FIGs. 3A to 5B, the attachment of the base film 112 to the
one or more removable films 114 and 116 via mechanical bonding (e.g.,
ultrasonic
bonding) is shown in detail. FIG. 3A illustrates a cross-sectional view of one
of the
removable films 114 or 116 of the visor system 180 of the present invention,
while
FIG. 3B illustrates a perspective view of the removable film 114 or 116 of
FIG. 3A.
FIG. 4A illustrates a cross-sectional view of the visor system 180 of the
present
invention where one removable film 114 or 116 is mechanically bonded to the
base
film 112, while FIG. 4B illustrates a perspective view of the visor system 180
of FIG.
4A. FIG. 5A illustrates a cross-sectional view of the visor system 180 of the
present
invention where a first removable film 114 is mechanically bonded to the base
film
112 and a second removable film 116 is mechanically bonded to the first
removable
film 114, while FIG. 5B illustrates a perspective view of the visor system of
FIG. 5A.
As shown in FIGs. 3A and 3B, the removable films 114 and 116 can each
include a biological indicator 128 attached, for example, to a centrally
located
surface of the removable film 114 or 116, such as via one or more strips of
tape 132
or any other suitable attachment means. The biological indicator 128 can be
used
to ensure that the removable films 114 and 116 are adequately sterilized via
EO gas
in a single, simultaneous, efficient, sterilization step when sterilized
separately or as
part of a single package that includes a surgical gown 101 and/or surgical
hood 178
of a personal protection and ventilation system 100.
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Next, as shown in FIGs. 4A and 4B, once the biological indicator 128 is
attached to the removable film 114 or 116, the removable film 114 or 116 can
be
mechanically bonded to an outer-facing surface 270 of a base film 112, while
the
inner-facing surface 272 of the base film 112 is the surface closest to a
wearer's
.. face when incorporated into a surgical hood 178 as described in more detail
below.
For the purposes of FIGs. 4A and 4B, reference is made to removable film 114.
As
shown, a plurality of mechanical bond points 124 can be disposed about a
perimeter
P2 of the removable film 114 between the removable film 114 and the outer-
facing
surface 270 of the base film 112 to join the two films together, while at the
same
time, a gap 126 is present between adjacent mechanical bond points 124 to
ensure
that all of the surfaces of the base film 112 and removable film 114 can be
adequately sterilized. The mechanical bond points 124 can be formed via any
suitable means, such as ultrasonic welding.
Further, as shown in FIGs. 5A and 5B, once the removable film 114 is
mechanically bonded to the base film 112 as described above with reference to
FIGs. 4A and 4B, an additional removable film 116 can be mechanically bonded
to
the removable film 114. Again, similar to the mechanical bonding between the
base
film 112 and the removable film 114, a plurality of mechanical bond points 124
can
be disposed about a perimeter P2 of the removable films 114 and 116 between
the
.. removable film 116 and the removable film 114 to join the two films
together, while
at the same time, a gap 126 is present between adjacent mechanical bond points
124 to ensure that all of the surfaces of removable film 114 and the removable
film
116 can be adequately sterilized. The mechanical bond points 124 can be formed
via any suitable means, such as ultrasonic welding.
Turning now to FIGs. 16-22, specific examples of the arrangement of the
plurality of mechanical bond points 124 are described in more detail, although
it is to
be understood that the configuration of the various patterns and spacing of
the
mechanical bond points 124 can vary based on application and the type of
sterilization cycle utilized to sterilize the visor system 180. It is also to
be
understood that the plurality of mechanical bond points 124 distributed or
disposed
about a perimeter P2 of the removable films 114 and/or 116 can be made using,
for
example, a male knurled patterned horn interfacing with a flat surface. The
male
knurled pattern horn can come in a variety of shapes and dimensions to form a
plurality of mechanical bond points 124 having a variety of shapes (e.g.,
circular,
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arcuate, rectangular, square, triangular, elliptical, hexagonal, etc.).
Further, by
controlling the depth of the bond formed by the patterned horn, more than one
peelable or removable film can be adhered to another layer simultaneously. For
instance, a first removable film 114 can be adhered to a base film 112, and a
second removable film 116 can be adhered to the first removable film 114.
Further,
each the plurality of mechanical bond points 124 formed between the second
removable film 116 and the first removable film 114 can be adjacent to or
concentrically positioned around the plurality of mechanical bond points 124
formed
between the base film 112 and the first removable film 114 in the same knurled
pattern. In addition, it is to be understood that although anvils are not
required to
form the patterns of the mechanical bond points 124 since the horn may be
patterned with the male knurl pattern, a multi-plunge process could also be
used
where multiple anvils are mounted to a single receiving plate that receives
multiple
horns executing multiple plunges at one time.
The various parameters that can be controlled during bonding to form the
desired mechanical bond points via ultrasonic bonding are shown below in Table
1:
Parameter Range
Frequency 20 kHz
Power Supply 4000 Watts
Weld Time 0.010 seconds-0.300 seconds
Collapse 0.001"-0.0075" (0.00254 cm-0.01905 cm)
Energy 0.5 Joules-1.5 Joules
Hold Time 0.01 seconds-0.5 seconds
Trigger Pressure 1 pound-10 pounds (0.45 kg-4.5 kg)
Gauge Pressure 10 psi-50 psi (0.069 MPa-0.35 MPa)
Down Speed 1 inch/sec-1.75 inch/second (2.54 cm/sec-4.45
cm/sec)
Amplitude 25%-85%
Peak Power 10%
Table 1: Ultrasonic Bonding Parameters
Now, various examples of patterns of mechanical bond points 124 will be
discussed in more detail. Specifically, FIG. 16 illustrates a front view of a
visor
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system 180 according to one embodiment of the present invention. In FIG. 16,
the
plurality of mechanical bond points 124 are arranged about the perimeter P2 of
the
removable film 114 in the form of circles having a diameter D. The diameter D
can
be any suitable diameter but, in some embodiments, can range from about 0.5
centimeters to about 2 centimeters, such as from about 0.75 centimeters to
about
1.75 centimeters, such as from about 1 centimeter to about 1.5 centimeters.
Moreover, if an additional removable film 116 (not shown) is included in the
visor
system 180, it can be attached to the first removable film 114 via a plurality
of bond
points 124 that can be in the form of a circle or any other suitable geometry
can be
positioned adjacent or concentrically around the outer edge of the plurality
of bond
points 124 joining the first removable film 114 to the base film 112. The
first
removable film 114 also includes tabs B1 and B2 to facilitate peeling of the
first
removable film 114 from the base film 112.
Further, FIG. 17 illustrates a front view of a visor system 180 according to
another embodiment of the present invention. As shown, plurality of mechanical
bond points 124 are in the form of an arcuate shape at the corners of the
first
removable film 114, where the arcuate shape follows the radius of curvature of
the
removable film layer 114, which includes tabs B1 and B2. The arcuate shape can
have an arc length L2 ranging from about 10 centimeters to about 15
centimeters,
such as from about 11 centimeters to about 14 centimeters, such as from about
12
centimeters to about 13 centimeters, while the radius of curvature R can range
from
about 3.5 centimeters to about 5.5 centimeters, such as from about 3.75
centimeters to about 5.25 centimeters, such as from about 4 centimeters to
about 5
centimeters. In addition, each of the arcuate mechanical bond points 124 can
terminate in a straight line perpendicular to the edge of the removable film
layer
114. Further, the mechanical bond points 124 can have a height H4 ranging from
about 0.4 centimeter to about 0.9 centimeters, such as from about 0.5
centimeters
to about 0.8 centimeters, such as from about 0.6 centimeters to about 0.7
centimeters. Without intending to be limited by any particular theory, the
present
inventors have found that such features and dimensions allow for a more
continuous
peel of the first removable film 114 from the base film 112 when in use.
Additionally,
a series of dashes or reference lines can be permanently or temporarily
disposed on
the first removable film 114, the base film 112, or both to ensure that the
arcuate-
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shaped mechanical bond points 124 positioned at the corners of the first
removable
film 114 are aligned with each other.
Meanwhile, FIG. 18 illustrates a front view of a visor system 180 according to
still another embodiment of the present invention where one of the plurality
of
5 mechanical bond points 124 at an upper edge of the removable film layer
114 can
be in the shape of a rectangle that can have a height H4 ranging from about
0.4
centimeter to about 0.9 centimeters, such as from about 0.5 centimeters to
about
0.8 centimeters, such as from about 0.6 centimeters to about 0.7 centimeters
and a
length ranging from about 2 centimeters to about 8 centimeters, such as from
about
10 3 centimeters to about 7 centimeters, such as from about 4 centimeters
to about 6
centimeters, where the features and dimensions allow for a more continuous
peel of
the first removable film 114 from the base film 112 when in use.
In addition, FIGs. 19-22 illustrate various zoomed in views of additional
visor
systems 180 of the present. For instance, FIG. 19 shows the peeling of a
15 removable film 114 from a base film 112, where a mechanical bond point
124 is
shown as being positioned on both the removable film 114 and the base film
112.
Further, FIG. 20 illustrates a zoomed in view of the rectangular shaped
mechanical
bond point 124 of the visor system 180 of FIG. 18. Moreover, FIG. 21
illustrates a
zoomed in view of one of the arcuate-shaped mechanical bond points 124 of the
visor system 180 of FIGs. 17-18. Lastly, FIG. 22 illustrates a zoomed in view
of a
visor system 180 according to yet another embodiment of the present invention
showing one of the circular-shaped mechanical bond points 124 of FIG. 16 in
more
detail.
FIGS. 6-8 demonstrate the use of the visor system 180 of the present
invention that includes the base film 112 and one or more removable films 114
and
116 described above in conjunction with a personal protection and ventilation
system 100. FIG. 6 illustrates a side view of a user wearing a personal
protection
and ventilation system 100 that includes the visor system 180 of the present
invention once completely donned. The user or wearer's head is completely
contained within a hood 178, while the visor system 180 of the present
invention
provides visibility in the form of a clear shield, and a light source 188 on a
helmet
190 provides illumination during a surgical procedure. Further, the hood 178
is
connected to the helmet 190 via connecting tabs 210 (see FIG. 7) present on
the
first side 266 and the second side 268 of the visor system 180, where the
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connecting tabs 210 mate or lock with the receiving tabs 208 on either side of
the
helmet 190.
Referring now to FIGs. 7-8, FIG. 7 illustrates a procedure for donning the
disposable surgical gown 101 and hood 178 with which the visor system 180 of
the
present invention is integrated, while FIG. 8 illustrates various adjustment
procedures that can be carried out while using a personal protection and
ventilation
system 100 that includes the visor system 180 of the present invention. First,
in
FIG. 7, a procedure by which a wearer can don the disposable surgical gown 101
with hood 178 and visor system 180 after donning the helmet 190, an air tube
184,
and a fan component or module 186 of the personal ventilation and protection
system 100 as described in more detail below with respect to FIG. 9 is shown.
First,
with an assistant, the wearer can insert his arms into the sleeves of the
disposable
surgical gown 101. Then, in step 2, the assistant can bend the connecting tabs
210
on the visor system 180 towards each other in the direction of the arrows as
shown,
and, next, in step 3, the assistant can move the hood 178 in the direction of
the
wearer to line up the connecting tabs 210 on the visor system 180 on the hood
178
with the receiving tabs 210 on the helmet 190. Further, as the visor system
180 is
connected to the helmet 190, in step 4, the assistant can position the hood
178 over
the helmet 190 and the air tube 184. Then, in step 5, the assistant can ensure
that
the hood 178 and gown 101 are properly donned and positioned about the body of
the wearer, and lastly, in step 6, the assistant can secure the gown 101 via
fastening means 118 (e.g., a zipper) by pulling the zipper downward as shown.
Further, in FIG. 8, various adjustment procedures that can be carried out
while using the personal protection and ventilation system 100 including the
visor
system 180 of the present invention are shown. In frames A and B, the removal
of
an outermost transparent or clear film 114 or 116 disposed on the visor system
180
of the hood 178 is shown, leaving base film 112 exposed. Removal of the film
114
or 116 may be desired when blood, tissue, etc. are present on the outermost
film
(e.g., removable film 114 or 116) and affect the wearer's visibility during a
surgical
procedure. In frame C, adjustment of the positioning of the light source 188
is
shown by the wearer grasping the lever 194, where the hood 178 is present
between the wearer's fingers and the lever 194 contained within the hood 178.
Lastly, in frame D, adjustment of the speed of the fan 182 by an assistant is
shown,
where the fan 182 can be adjust to three different speeds (e.g., low, medium,
and
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high) by turning a fan speed adjustment knob 264 either by unfastening (e.g.,
unzipping) the gown 101 via fastening means 118 (see FIG. 7, step 6), or
tactically
through the gown 101 without unfastening the gown 101.
The various components of a personal protection and ventilation system 100
-- with which the visor system 180 of the present invention can be used are
discussed
in more detail with references to FIGs. 9-15.
FIG. 9 illustrates the various components of a personal protection and
ventilation system 100 that can include the visor system 180 of the present
invention. The system 100 can include a disposable surgical gown 101 that can
-- include a separate or integral hood 178 and visor system 180; and a helmet
190 that
can include a front portion 252 with receiving tabs 208 for connecting with
the hood
178 via connecting tabs 210 present on the visor system 180 (see FIG. 7), an
air
conduit 228 with an air outlet 214, and a light source 188 with a support 196.
As
shown in FIG. 9, the air outlet 214 can be positioned at an angle a that
ranges from
about 40 to about 85 , such as from about 45 to about 87.5 , such as from
about
50 to about 80 with respect to a y-axis or horizontal direction towards an x-
axis or
vertical direction. It is believed that angles falling within the
aforementioned ranges
allow for a direction of air flow that reduces fogging in the visor system
180, limits
drying of the wearer's eyes, and also provides sufficient cooling to the light
source
188.
Referring still to FIG. 9, the system 100 can also include an air tube 184 as
well as a fan component or module 186 that includes a fan 182 and can also
include
a built-in power source 216 such as a battery, a power switch 262, and a fan
speed
adjustment knob 264. However, it is also to be understood that the power
source
216 can be a separate component from the fan component or module 186 that is
attached separately to the belt 206. Further, the air tube 184 can be attached
to the
fan component or module 186 via fitting 224, while the air tube 184 can be
attached
to the helmet 190 via fitting 226 at an opposite end of the air tube 184. The
fan
component or module 186 can be attached to a belt 206 to secure the fan
-- component or module 186 about the rear waist area of a wearer, and the fan
component or module 186 can be attached to the belt 206 via attachment or
locking
mechanism 198.
FIG. 10 illustrates a front of the disposable surgical gown 101 of FIG. 9 that
can be used in conjunction with the visor system 180 of the present invention.
The
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disposable surgical gown includes a front 158 and a rear 160 that can be worn
by
medical personnel during a surgical procedure, such as an orthopedic surgical
procedure or any other procedure where protection from bodily fluids, bone
fragments, etc. is desired. The disposable surgical gown 101 has a waist
portion
130 defined between a proximal end 154 and a distal end 156, where the
proximal
end 154 and the distal end 156 define a front panel 102. As shown, the
proximal
end 154 includes a hood 178 with the visor system 180, while the distal end
156
defines a portion of the gown 101 that is closest to the wearer's feet. As
shown in
FIG. 10, the hood 178 can be integral with the gown 101 such that the gown 101
-- and hood 178 form a single garment, where the hood 178 can be sewn to the
gown
101 at seam 170. On the other hand, as shown in FIG. 12, in some embodiments,
the hood 178 can be a separate component from the surgical gown 101, where the
hood 178 can be tucked into the surgical gown 101 inside collar 110. The gown
101
also includes sleeves 104 and cuffs 106. The front panel 102, sleeves 104, and
-- hood 178 can be formed from a laminate of an elastic film and nonwoven
materials,
as discussed in more detail below. Further, the sleeves 104 can be raglan
sleeves,
which means that each sleeve 104 extends fully to the collar 110 (see FIG.
12),
where a front diagonal seam 164 extends from the underarm up to the collarbone
of
the wearer and a rear diagonal seam 166 (see FIG. 11) extends from the
underarm
-- up to the collarbone of the wearer to attach the sleeves 104 to the front
panel 102
and rear panels 120 and 122 of the gown 101. The front diagonal seams 164 and
the rear diagonal seams 166 of the sleeves 104 can be sewn to the front panel
102
and rear panels 120 and 122 of the gown. Further, the each sleeve 104 can
include
a seam 176 that can extend from the underarm area down to the cuff 104, where
such sleeves 176 can be seamed thermally so that the sleeves 104 pass ASTM-
1671 "Standard Test Method for Resistance of Materials Used in Protective
Clothing
to Penetration by Blood-Borne Pathogens Using Phi-X174 Bacteriophage
Penetration as a Test System."
FIG. 11 illustrates a rear of the disposable surgical gown 101. The proximal
end 154 and the distal end 156 define a first rear panel 120 and a second rear
panel
122. The first rear panel 120 and second rear panel 122 can be formed of a
laminate of nonwoven materials, as discussed in more detail below. Further, as
shown in FIG. 11, the hood 178 can be integral with the gown 101 such that the
gown 101 and hood 178 form a single garment, where the hood 178 can be sewn to
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the gown 101 at seam 170. On the other hand, as shown in FIG. 13, in some
embodiments, the hood 178 can be a separate component from the surgical gown
101, where the hood 178 can be tucked into the surgical gown 101 inside collar
110.
In addition, as shown in FIGs. 11 and 13, the hood 178 can include a first
portion
-- 256 and a second portion 256 as separated by a seam 254, where such the
materials used to form the first and second portions 258 materials will be
discussed
in more detail below, although, in some embodiments, it is to be understood
that the
hood 178 can be formed entirely of a first material 256. Further, the first
rear panel
120 can be sewn to the front panel 102 at a seam 172, while the second rear
panel
122 can be sewn to the front panel 102 at a seam 174, where the first rear
panel
120 can be ultrasonically bonded to the front panel 102 at seam 172 and the
second
rear panel 122 can be ultrasonically bonded to the front panel 102 at seam
174,
where the ultrasonic bonding results in seams 172 and 174 that have improved
liquid barrier protection than sewn seams. For instance, such ultrasonic
bonding of
the rear panels 120 and 122 to the front panel 102 can result in seams 172 and
174
that can have a hydrohead ranging from about 25 cm to about 100 cm, such as
from
about 30 cm to about 75 cm, such as from about 40 cm to about 60 cm, while
sewn
seams only have a hydrohead of about 7 cm, where the hydrohead is determined
by
providing a clear open-ended tube and clamping the seamed material over the
bottom end, filling the tube slowly with water from its top end, and measuring
how
high the column of water is before water passes through the bottom end of the
tube.
Further, a rear fastening means 118 such as zipper can be used to secure the
gown
101 once it is worn by the wearer. Depending on whether the hood 178 is
integral
with the gown 101 or separate from the gown 101, the fastening means 118 can
extend into the area of the hood 178 (see FIG. 11) or can end at the collar
110 (see
FIG. 13).
FIG. 14 illustrates a cross-sectional view of a first material 200 which can
be
used to form the front panel 102, the sleeves 104, and the hood 178 of the
surgical
gown 101 of FIGs. 9-13, where the first material 200 passes ASTM-1671
"Standard
Test Method for Resistance of Materials Used in Protective Clothing to
Penetration
by Blood-Borne Pathogens Using Phi-X174 Bacteriophage Penetration as a Test
System." In some embodiments, the entire hood 178 can be formed from the first
material 200, while, in other embodiments, as shown in FIGs. 10-13, the first
portion
256 of the hood 178, which encompasses the entire hood 178 at the front 158 of
the
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gown 101 and the portion of the hood 178 above seam 254 on the rear of the
gown
160 and can be formed from the first material 200, while the second portion
258 of
the hood can be formed from a second material 300 as discussed in more detail
below. The first material 200 can be a laminate that includes an outer
spunbond
5 layer 142, an elastic film 144 containing an first skin layer 144A and a
second skin
layer 144C with a core layer 144B disposed therebetween, and a spunbond-
meltblown-spunbond laminate 146 containing a spunbond layer 146A and a
spunbond layer 146C with a meltblown layer 146B disposed therebetween. The
outer spunbond layer 142 can form an outer-facing surface 202 of the front
panel
10 102 on the front 158 of the gown 101, the sleeves 104, and the hood 178,
while the
spunbond layer 146C of the SMS laminate 146 can form the body-facing surface
or
inner-facing surface 204 of the front panel 102 and the sleeves 104 of the
surgical
gown 101 as well as the hood 178. As discussed in more detail below, the outer
spunbond layer 142 and one or more layers of the SMS laminate 146 can include
a
15 slip additive to enhance the softness and comfort of the first material
200, while one
or more layers of the elastic film 144 can include a fluorochemical additive
to
enhance the barrier performance of the first material 200. The overall
spunbond-
film-SMS laminate arrangement of the first material 200 contributes to the
moisture
vapor breathability of the surgical gown 101 while providing impermeability to
air to
20 protect the wearer from exposure to blood, viruses, bacteria, and other
harmful
contaminants. In other words, the first material 200 allows for an air
volumetric flow
rate ranging that is less than about 1 standard cubic feet per minute (scfm),
such as
less than about 0.5 scfm, such as less than about 0.25 scfm, such as less than
about 0.1 scfm, such as 0 scfm, as determined at 1 atm (14.7 psi) and 20 C (68
F).
FIG. 15 illustrates a second material 300 that can be used to form the
surgical gown 101 of FIGs. 9-13, where the second material 300 can form the
first
rear panel 120 and the second rear panel 122. Further, in some embodiments as
shown in FIGs. 11 and 13, the second portion 258 of the hood 178 below seam
254
on the rear of the gown 160 can be formed from the second material 300 to
provide
-- some breathability to the second or lower portion 258 of the hood 178. The
second
material 300 can be a laminate that includes a first spunbond layer 148, a
meltblown
layer 150, and a second spunbond layer 152. The first spunbond layer 148 can
form an outer-facing surface 302 of the first rear panel 120 and the second
rear
panel 122 of the surgical gown 101, while the second spunbond layer 152 can
form
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the body-facing surface or inner-facing surface 304 of the first rear panel
120 and
the second rear panel 122 of the surgical gown 101. As discussed in more
detail
below, the spunbond layers 148 and 152 can include a slip additive to enhance
the
softness and comfort of the second material 300, while the overall spunbond-
meltblown-spunbond (SMS) laminate arrangement of the second material
contributes to the air breathability of the surgical gown 101.
The various components of the disposable surgical gown 101 of the personal
protection and ventilation system 100 with which the visor system 180 of the
present
invention can be used are discussed in more detail below. As an initial
matter, it is
to be understood that any of the spunbond layers, meltblown layers, or elastic
film
layers of the first material 200 and/or the second material 300 can include
pigments
to impart the gown 101 with a gray color, which provides anti-glare and light
reflectance properties, which, in turn, can provide a better visual field
during
surgeries or other procedures where operating room lighting can result in poor
visual conditions, resulting in glare that causes visual discomfort, and leads
to
fatigue of operating room staff during surgical procedures.
For instance, examples of suitable pigments used to arrive at the desired
gray pigment for the gown include, but are not limited to, titanium dioxide
(e.g., SCC
11692 concentrated titanium dioxide), zeolites, kaolin, mica, carbon black,
calcium
oxide, magnesium oxide, aluminum hydroxide, and combinations thereof. In
certain
cases, for instance, each of the various individual layers of the gown
materials 200
and 300 can include titanium dioxide in an amount ranging from about 0.1 wt.%
to
about 10 wt.%, in some embodiments, from about 0.5 wt.% to about 7.5 wt.%, and
in some embodiments, from about 1 wt.% to about 5 wt.% based on the total
weight
of the individual layer. The titanium dioxide can have a refractive index
ranging from
about 2.2 to about 3.2, such as from about 2.4 to about 3, such as from about
2.6 to
about 2.8, such as about 2.76, to impart the material 200 with the desired
light
scattering and light absorbing properties. Further, each of the various
individual
layers of the gown materials 200 and 300 can also include carbon black in an
amount ranging from about 0.1 wt.% to about 10 wt.%, in some embodiments, from
about 0.5 wt.% to about 7.5 wt.%, and in some embodiments, from about 1 wt.%
to
about 5 wt.% based on the total weight of the individual layer. The carbon
black can
have a refractive index ranging from about 1.2 to about 2.4, such as from
about 1.4
to about 2.2, such as from about 1.6 to about 2 to impart the material 200
with the
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desired light scattering and light absorbing properties. Each of the various
individual
layers of the gown materials 200 and 300 can also include a blue pigment in an
amount ranging from about 0.1 wt.% to about 10 wt.%, in some embodiments, from
about 0.5 wt.% to about 7.5 wt.%, and in some embodiments, from about 1 wt.%
to
about 5 wt.% based on the total weight of the individual layer. The
combination of
the carbon black and blue pigment improves the ability of the nonwoven
materials
and film of the present invention to absorb light.
As a result of the incorporation of one or more of the aforementioned
pigments into the gown 101 materials, the first material 200 and/or the second
material 300 can thus be a sufficient shade of gray to prevent glare. Gray is
an
imperfect absorption of the light or a mixture of black and white, where it is
to be
understood that although black, white, and gray are sometimes described as
achromatic or hueless colors, a color may be referred to as "black" if it
absorbs all
frequencies of light. That is, an object that absorbs all wavelengths of light
that strike
it so that no parts of the spectrum are reflected is considered to be black.
Black is
darker than any color on the color wheel or spectrum. In contrast, white is
lighter
than any color on the color wheel or spectrum. If an object reflects all
wavelengths
of light equally, that object is considered to be white.
As mentioned above, the front panel 102, sleeves 104, and hood 178 (e.g.,
all of the hood 178 or at least the first portion 256 of the hood 178 as
described
above) of the gown 101 can be formed from a first material 200. The first
material
200 can be a stretchable elastic breathable barrier material that renders the
aforementioned sections of the gown 101 impervious to bodily fluids and other
liquids while still providing satisfactory levels of moisture vapor
breathability and/or
moisture vapor transmission and stretchabiilty. The first material 200 can
include a
combination of a film, which can serve as the key barrier and elastic
component of
the surgical gown 101, and one or more nonwoven layers (e.g., spunbond layers,
meltblown layers, a combination thereof, etc.) to provide softness and
comfort. The
film can be configured to exhibit elastic properties such that the film
maintains its
fluid barrier characteristics even when elongated in the machine direction by
amounts at least as twice as high as currently available gowns such that the
gown
101 passes ASTM-1671 "Standard Test Method for Resistance of Materials Used in
Protective Clothing to Penetration by Blood-Borne Pathogens Using Phi-X174
Bacteriophage Penetration as a Test System." Meanwhile, as a result of the
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inclusion of the nonwoven layers in conjunction with the elastic film, the
overall first
material 200 can have an increased bending modulus to achieve the desired
pliability and softness which results in a material that is comfortable to the
wearer.
As discussed above, in one particular embodiment, the first material 200 can
include an outer spunbond layer 142, a spunbond-meltblown-spunbond laminate
146, and an elastic film 144 positioned therebetween. The outer spunbond layer
142 can form an outer-facing surface 202 of the front panel 102, sleeves 104,
and
hood 178 of the surgical gown 101, while one of the spunbond layers of the SMS
laminate 146 can form the body-facing surface or inner-facing surface 204 of
the
front panel 102, sleeves 104, and hood 178 of the surgical gown 101. Further,
the
outer spunbond layer 142 and one or more layers of the SMS laminate 146 can
include a slip additive to achieve the desired softness, while the film 144
can include
a fluorochemical additive to increase the surface energy of the elastic film
144 and
enhance the ability of the elastic film 144 to serve as a barrier to bodily
fluids and
-- tissues, including fatty oils that may be generated during very invasive
surgeries as
a result of the maceration of fatty tissue. Each of these components of the
first
material 200 is described in more detail below.
The outer spunbond layer 142 can be formed from any suitable polymer that
provides softness, stretch, and pliability to the first material 200. For
instance, the
-- outer spunbond layer 142 can be formed from a semi-crystalline polyolefin.
Exemplary polyolefins may include, for instance, polyethylene, polypropylene,
blends
and copolymers thereof. In one particular embodiment, a polyethylene is
employed
that is a copolymer of ethylene and an a-olefin, such as a C3-C20 a-olefin or
C3-C12
a-olefin. Suitable a-olefins may be linear or branched (e.g., one or more C1-
C3 alkyl
branches, or an aryl group). Specific examples include 1-butene; 3-methyl-1-
butene; 3,3-dimethy1-1-butene; 1-pentene; 1-pentene with one or more methyl,
ethyl
or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl
substituents; 1-heptene with one or more methyl, ethyl or propyl substituents;
1-
octene with one or more methyl, ethyl or propyl substituents; 1-nonene with
one or
-- more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-
substituted 1-
decene; 1-dodecene; and styrene. Particularly desired a-olefin co-monomers are
1-
butene, 1-hexene and 1-octene. The ethylene content of such copolymers may be
from about 60 mole% to about 99 mole%, in some embodiments from about 80
mole% to about 98.5 mole%, and in some embodiments, from about 87 mole% to
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about 97.5 mole%. The a-olefin content may likewise range from about 1 mole%
to
about 40 mole%, in some embodiments from about 1.5 mole% to about 15 mole%,
and in some embodiments, from about 2.5 mole% to about 13 mole%.
The density of the polyethylene may vary depending on the type of polymer
employed, but generally ranges from 0.85 to 0.96 grams per cubic centimeter
("g/cm3"). Polyethylene "plastomers", for instance, may have a density in the
range
of from 0.85 to 0.91 g/cm3. Likewise, "linear low density polyethylene"
("LLDPE")
may have a density in the range of from 0.91 to 0.940 g/cm3; "low density
polyethylene" ("LDPE") may have a density in the range of from 0.910 to 0.940
g/cm3; and "high density polyethylene" ("HDPE") may have density in the range
of
from 0.940 to 0.960 g/cm3. Densities may be measured in accordance with ASTM
1505. Particularly suitable ethylene-based polymers for use in the present
invention
may be available under the designation EXACTTm from ExxonMobil Chemical
Company of Houston, Texas. Other suitable polyethylene plastomers are
available
under the designation ENGAGETM and AFFINITYTm from Dow Chemical Company
of Midland, Michigan. Still other suitable ethylene polymers are available
from The
Dow Chemical Company under the designations DOWLEXTM (LLDPE) and
ATTANETm (ULDPE). Other suitable ethylene polymers are described in U.S.
Patent Nos. 4,937,299 to Ewen et al.; 5,218,071 to Tsutsui et al.; 5,272,236
to Lai
et al.; and 5,278,272 to Lai et al., which are incorporated herein in their
entirety by
reference thereto for all purposes.
Of course, the outer spunbond layer 142 of the first material 200 is by no
means limited to ethylene polymers. For instance, propylene polymers may also
be
suitable for use as a semi-crystalline polyolefin. Suitable propylene polymers
may
include, for instance, polypropylene homopolymers, as well as copolymers or
terpolymers of propylene with an a-olefin (e.g., C3-C20) comonomer, such as
ethylene, 1-butene, 2-butene, the various pentene isomers, 1-hexene, 1-octene,
1-
nonene, 1-decene, 1-unidecene, 1-dodecene, 4-methyl-1-pentene, 4-methyl-1-
hexene, 5-methyl-1-hexene, vinylcyclohexene, styrene, etc. The comonomer
content of the propylene polymer may be about 35 wt.% or less, in some
embodiments from about 1 wt.% to about 20 wt.%, in some embodiments, from
about 2 wt.% to about 15 wt.%, and in some embodiments from about 3 wt.% to
about 10 wt.%. The density of the polypropylene (e.g., propylene/a-olefin
copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in some
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embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3
to 0.91 g/cm3. In one particular embodiment, the outer spunbond layer 142 can
include a copolymer of polypropylene and polyethylene. The polypropylene can
have a refractive index ranging from about 1.44 to about 1.54, such as from
about
5 1.46 to about 1.52, such as from about 1.48 to about 1.50, such as about
1.49, while
the polyethylene can have a refractive index ranging from about 1.46 to about
1.56,
such as from about 1.48 to about 1.54, such as from about 1.50 to about 1.52,
such
as about 1.51, to impart the material 200 with the desired light scattering
and light
absorbing properties.
10 Suitable propylene polymers are commercially available under the
designations VISTAMAXXTm from ExxonMobil Chemical Co. of Houston, Texas;
FINATM (e.g., 8573) from Atofina Chemicals of Feluy, Belgium; TAFMERTm
available
from Mitsui Petrochemical Industries; and VERSIFYTM available from Dow
Chemical
Co. of Midland, Michigan. Other examples of suitable propylene polymers are
15 -- described in U.S. Patent No. 6,500,563 to Datta, et al.; 5,539,056 to
Yang, et al.;
and 5,596,052 to Resconi, et al., which are incorporated herein in their
entirety by
reference thereto for all purposes.
Any of a variety of known techniques may generally be employed to form the
polyolefins. For instance, olefin polymers may be formed using a free radical
or a
20 coordination catalyst (e.g., Ziegler-Natta or metallocene). Metallocene-
catalyzed
polyolefins are described, for instance, in U.S. Patent Nos. 5,571,619 to
McAlpin et
at; 5,322,728 to Davis et al.; 5,472,775 to Obijeski et al.; 5,272,236 to Lai
et al.; and
6,090,325 to Wheat, et al., which are incorporated herein in their entirety by
reference thereto for all purposes.
25 The melt flow index (MI) of the polyolefins may generally vary, but is
typically
in the range of about 0.1 grams per 10 minutes to about 100 grams per 10
minutes,
in some embodiments from about 0.5 grams per 10 minutes to about 30 grams per
10 minutes, and in some embodiments, about 1 to about 10 grams per 10 minutes,
determined at 190 C. The melt flow index is the weight of the polymer (in
grams)
that may be forced through an extrusion rheometer orifice (0.0825-inch
diameter)
when subjected to a force of 2160 grams in 10 minutes at 190 C, and may be
determined in accordance with ASTM Test Method D1238-E.
In addition to a polyolefin, the outer spunbond layer 142 can also include a
slip additive to enhance the softness of the outer spunbond layer 142. The
slip
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26
additive can also reduce the coefficient of friction and increase the
hydrohead of the
outer spunbond layer 142 of the front panel 102 and the sleeves 104. Such a
reduction in the coefficient of friction lessens the chance of the gown 101
being cut
or damaged due to abrasions and also prevents fluids from seeping through the
first
material 200. Instead, at least in part due to the inclusion of the slip
additive, fluid
that contacts the outer-facing surface 202 of the gown 101 can remain in
droplet
form and run vertically to the distal end 156 of the gown 101 and onto the
floor. The
slip additive can also reduce the glare of the first material 200 in the
operating room
by reducing the light reflectance of the first material and can also render
the first
material 200 more opaque than the standard gown material when contacted with
fats and lipids during surgery, where the standard gown material turns
transparent
upon contact with fats and lipids, which can result in the wearer having some
concern that the barrier properties of a standard gown have been compromised.
The slip additive can function by migrating to the surface of the polymer used
to form the outer spunbond layer 142, where it can provide a coating that
reduces
the coefficient of friction of the outer-facing surface 202 of the first
material 200.
Variants of fatty acids can be used as slip additives. For example, the slip
additive
can be erucamide, oleamide, stearamide, behenamide, oleyl palmitamide, stearyl
erucamide, ethylene bis-oleamide, N,N'-Ethylene Bis(Stearamide) (EBS), or a
combination thereof. Further, the slip additive have a refractive index
ranging from
about 1.42 to about 1.52, such as from about 1.44 to about 1.50, such as from
about
1.46 to about 1.48, such as about 1.47, to impart the material 200 with the
desired
light scattering and light absorbing properties by reducing the refractive
index. The
slip additive can be present in the outer spunbond layer 142 in an amount
ranging
from about 0.1 wt.% to about 4 wt.%, such as from about 0.25 wt.% to about 3
wt.%,
such as from about 0.5 wt.% to about 2 wt.% based on the total weight of the
outer
spunbond layer 142. In one particular embodiment, the slip additive can be
present
in an amount of about 1 wt.% based on the total weight of the outer spunbond
layer
142.
In addition to the polyolefin and slip additive, the outer spunbond layer 142
can also include one or more pigments to help achieve the desired gray color
of the
gown 101. Examples of suitable pigments include, but are not limited to,
titanium
dioxide (e.g., SCC 11692 concentrated titanium dioxide), zeolites, kaolin,
mica,
carbon black, calcium oxide, magnesium oxide, aluminum hydroxide, and
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combinations thereof. In certain cases, for instance, the outer spunbond layer
142
can include titanium dioxide in an amount ranging from about 0.1 wt.% to about
10
wt.%, in some embodiments, from about 0.5 wt.% to about 7.5 wt.%, and in some
embodiments, from about 1 wt.% to about 5 wt.% based on the total weight of
the
outer spunbond layer 142. The titanium dioxide can have a refractive index
ranging
from about 2.2 to about 3.2, such as from about 2.4 to about 3, such as from
about
2.6 to about 2.8, such as about 2.76, to impart the material 200 with the
desired light
scattering and light absorbing properties. Further, the outer spunbond layer
142 can
also include carbon black in an amount ranging from about 0.1 wt.% to about 10
-- wt.%, in some embodiments, from about 0.5 wt.% to about 7.5 wt.%, and in
some
embodiments, from about 1 wt.% to about 5 wt.% based on the total weight of
the
outer spunbond layer 142. The carbon black can have a refractive index ranging
from about 1.2 to about 2.4, such as from about 1.4 to about 2.2, such as from
about 1.6 to about 2 to impart the material 200 with the desired light
scattering and
-- light absorbing properties. The outer spunbond layer 142 can also include a
blue
pigment in an amount ranging from about 0.1 wt.% to about 10 wt.%, in some
embodiments, from about 0.5 wt.% to about 7.5 wt.%, and in some embodiments,
from about 1 wt.% to about 5 wt.% based on the total weight of the individual
layer.
The combination of the carbon black and blue pigment improves the ability of
the
-- outer spunbond layer 142 to absorb light.
Regardless of the specific polymer or polymers and additives used to form
the outer spunbond layer 142, the outer spunbond layer 142 can have a basis
weight ranging from about 5 gsm to about 50 gsm, such as from about 10 gsm to
about 40 gsm, such as from about 15 gsm to about 30 gsm. In one particular
-- embodiment, the outer spunbond layer 142 can have a basis weight of about
20
gsm (about 0.6 osy).
The elastic film 144 of the first material 200 can be formed from any suitable
polymer or polymers that are capable of acting as a barrier component in that
it is
generally impervious, while at the same time providing moisture vapor
breathability
-- to the first material 200. The elastic film 144 can be formed from one or
more layers
of polymers that are melt-processable, i.e., thermoplastic. In one particular
embodiment, the elastic film 144 can be a monolayer film. If the film is a
monolayer,
any of the polymers discussed below in can be used to form the monolayer. In
other embodiments, the elastic film 144 can include two, three, four, five,
six, or
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seven layers, where each of the layers can be formed from any of the polymers
discussed below, where the one or more layers are formed from the same or
different materials. For instance, in one particular embodiment the elastic
film 144
can include a core layer 144B disposed between two skin layers, 144A and 144C.
Each of these components of the film are discussed in more detail below.
First, the elastic film core layer 144B can be formed from one or more semi-
crystalline polyolefins. Exemplary semi-crystalline polyolefins include
polyethylene,
polypropylene, blends and copolymers thereof. In one particular embodiment, a
polyethylene is employed that is a copolymer of ethylene and an a-olefin, such
as a
C3-C20 a-olefin or C3-C12 a-olefin. Suitable a-olefins may be linear or
branched
(e.g., one or more C1-C3 alkyl branches, or an aryl group). Specific examples
include 1-butene; 3-methyl-1-butene; 3,3-dimethy1-1-butene; 1-pentene; 1-
pentene
with one or more methyl, ethyl or propyl substituents; 1-hexene with one or
more
methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl
or
propyl substituents; 1-octene with one or more methyl, ethyl or propyl
substituents;
1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl
or
dimethyl-substituted 1-decene; 1-dodecene; and styrene. Particularly desired a-
olefin comonomers are 1-butene, 1-hexene and 1-octene. The ethylene content of
such copolymers may be from about 60 mole% to about 99 mole%, in some
embodiments from about 80 mole% to about 98.5 mole%, and in some
embodiments, from about 87 mole% to about 97.5 mole%. The a-olefin content
may likewise range from about 1 mole% to about 40 mole%, in some embodiments
from about 1.5 mole% to about 15 mole%, and in some embodiments, from about
2.5 mole% to about 13 mole%.
Particularly suitable polyethylene copolymers are those that are "linear" or
"substantially linear." The term "substantially linear" means that, in
addition to the
short chain branches attributable to comonomer incorporation, the ethylene
polymer
also contains long chain branches in the polymer backbone. "Long chain
branching"
refers to a chain length of at least 6 carbons. Each long chain branch may
have the
same comonomer distribution as the polymer backbone and be as long as the
polymer backbone to which it is attached. Preferred substantially linear
polymers
are substituted with from 0.01 long chain branch per 1000 carbons to 1 long
chain
branch per 1000 carbons, and in some embodiments, from 0.05 long chain branch
per 1000 carbons to 1 long chain branch per 1000 carbons. In contrast to the
term
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"substantially linear", the term "linear" means that the polymer lacks
measurable or
demonstrable long chain branches. That is, the polymer is substituted with an
average of less than 0.01 long chain branch per 1000 carbons.
The density of a linear ethylene/a-olefin copolymer is a function of both the
length and amount of the a-olefin. That is, the greater the length of the a-
olefin and
the greater the amount of a-olefin present, the lower the density of the
copolymer.
Although not necessarily required, linear polyethylene "plastomers" are
particularly
desirable in that the content of a-olefin short chain branching content is
such that
the ethylene copolymer exhibits both plastic and elastomeric characteristics ¨
i.e., a
"plastomer." Because polymerization with a-olefin comonomers decreases
crystallinity and density, the resulting plastomer normally has a density
lower than
that of a polyethylene thermoplastic polymer (e.g., LLDPE), which typically
has a
density (specific gravity) of from about 0.90 grams per cubic centimeter
(g/cm3) to
about 0.94 g/cm3, but approaching and/or overlapping that of an elastomer,
which
typically has a density of from about 0.85 g/cm3 to about 0.90 g/cm3,
preferably from
0.86 to 0.89. For example, the density of the polypropylene (e.g., propylene/a-
olefin
copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in some
embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3
to 0.91 g/cm3. Despite having a density similar to elastomers, plastomers
generally
exhibit a higher degree of crystallinity, are relatively non-tacky, and may be
formed
into pellets that are non-adhesive-like and relatively free flowing.
Preferred polyethylenes for use in the present invention are ethylene-based
copolymer plastomers available under the designation EXACTTm from ExxonMobil
Chemical Company of Houston, Texas. Other suitable polyethylene plastomers are
available under the designation ENGAGE TM and AFFINITYTm from Dow Chemical
Company of Midland, Michigan. An additional suitable polyethylene-based
plastomer is an olefin block copolymer available from Dow Chemical Company of
Midland, Michigan under the trade designation INFUSETM, which is an
elastomeric
copolymer of polyethylene. Still other suitable ethylene polymers are low
density
polyethylenes (LDPE), linear low density polyethylenes (LLDPE) or ultralow
linear
density polyethylenes (ULDPE), such as those available from The Dow Chemical
Company under the designations ASPUNTM (LLDPE), DOWLEXTM (LLDPE) and
ATTANETm (ULDPE). Other suitable ethylene polymers are described in U.S.
Patent Nos. 4,937,299 to Ewen, et al., 5,218,071 to Tsutsui et al., 5,272,236
to Lai
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et al., and 5,278,272 to Lai et al., which are incorporated herein in their
entirety by
reference thereto for all purposes.
Of course, the elastic film core layer 144B of the present invention is by no
means limited to ethylene polymers. For instance, propylene plastomers may
also
5 be suitable for use in the film. Suitable plastomeric propylene polymers
may
include, for instance, polypropylene homopolymers, copolymers or terpolymers
of
propylene, copolymers of propylene with an a-olefin (e.g., C3-C20) comonomer,
such
as ethylene, 1-butene, 2-butene, the various pentene isomers, 1-hexene, 1-
octene,
1-nonene, 1-decene, 1-unidecene, 1-dodecene, 4-methyl-1-pentene, 4-methyl-1-
10 hexene, 5-methyl-1-hexene, vinylcyclohexene, styrene, etc. The comonomer
content of the propylene polymer may be about 35 wt.% or less, in some
embodiments from about 1 wt.% to about 20 wt.%, in some embodiments from
about 2 wt.% to about 15 wt.%, and in some embodiments from about 3 wt.% to
about 10 wt.%. Preferably, the density of the polypropylene (e.g., propylene/a-
olefin
15 copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in
some
embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3
to 0.91 g/cm3.
Suitable propylene polymers are commercially available under the
designations VISTAMAXXTm (e.g., 6102), a propylene-based elastomer from
20 ExxonMobil Chemical Co. of Houston, Texas; FINATM (e.g., 8573) from
Atofina
Chemicals of Feluy, Belgium; TAFMERTm available from Mitsui Petrochemical
Industries; and VERSIFYTM available from Dow Chemical Co. of Midland,
Michigan.
Other examples of suitable propylene polymers are described in U.S. Patent
Nos.
5,539,056 to Yang, et al., 5,596,052 to Resconi, et al., and 6,500,563 to
Datta et
25 at, which are incorporated herein in their entirety by reference thereto
for all
purposes. In one particular embodiment, the elastic film core layer 144B
includes
polypropylene. The polypropylene can have a refractive index ranging from
about
1.44 to about 1.54, such as from about 1.46 to about 1.52, such as from about
1.48
to about 1.50, such as about 1.49 to help impart the material 200 with the
desired
30 light scattering and light absorbing properties.
Any of a variety of known techniques may generally be employed to form the
semi-crystalline polyolefins. For instance, olefin polymers may be formed
using a
free radical or a coordination catalyst (e.g., Ziegler-Natta). Preferably, the
olefin
polymer is formed from a single-site coordination catalyst, such as a
metallocene
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catalyst. Such a catalyst system produces ethylene copolymers in which the
comonomer is randomly distributed within a molecular chain and uniformly
distributed across the different molecular weight fractions. Metallocene-
catalyzed
polyolefins are described, for instance, in U.S. Patent Nos. 5,272,236 to Lai
et al.,
5,322,728 to Davis et al., 5,472,775 to Obiieski et al., 5,571,619 to McAlpin
et al.,
and 6,090,325 to Wheat, et al., which are incorporated herein in their
entirety by
reference thereto for all purposes. Examples of metallocene catalysts include
bis(n-
butylcyclopentadienyl)titanium dichloride, bis(n-
butylcyclopentadienyl)zirconium
dichloride, bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconium
dichloride,
bis(methylcyclopentadienyl)titanium dichloride, bis(methylcyclopentadienyl)
zirconium dichloride, cobaltocene, cyclopentadienyltitanium trichloride,
ferrocene,
hafnocene dichloride, isopropyl(cyclopentadieny1,-1-flourenyl)zirconium
dichloride,
molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene,
titanocene dichloride, zirconocene chloride hydride, zirconocene dichloride,
and so
forth. Polymers made using metallocene catalysts typically have a narrow
molecular weight range. For instance, metallocene-catalyzed polymers may have
polydispersity numbers (Mw/Mn) of below 4, controlled short chain branching
distribution, and controlled isotacticity.
The melt flow index (MI) of the semi-crystalline polyolefins may generally
vary, but is typically in the range of about 0.1 grams per 10 minutes to about
100
grams per 10 minutes, in some embodiments from about 0.5 grams per 10 minutes
to about 30 grams per 10 minutes, and in some embodiments, about 1 to about 10
grams per 10 minutes, determined at 190 C. The melt flow index is the weight
of
the polymer (in grams) that may be forced through an extrusion rheometer
orifice
(0.0825-inch diameter) when subjected to a force of 5000 grams in 10 minutes
at
190 C, and may be determined in accordance with ASTM Test Method D1238-E.
In addition to a polyolefin such as polypropylene, the elastic film core layer
144B can also include a fluorochemical additive to increase the surface energy
of
the elastic film 144, which, in turn, increases the imperviousness of the
elastic film
144 to bodily fluids and biologic materials such as fatty oils that may be
generated
during very invasive surgeries. One example of a fluorochemical additive
contemplated for use in the core layer 144B is a fluoroalkyl acrylate
copolymer such
as Unidyne TG from Daikin. The fluorochemical additive can have a refractive
index that is less than about 1.4 in order to lower the refractive index of
the elastic
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film core layer 144B. For instance, the fluorochemical additive can have a
refractive
index ranging from about 1.2 to about 1.4, such as from about 1.22 to about
1.38,
such as from about 1.24 to about 1.36. Without intending to be limited by any
particular theory, it is believed that the fluorochemical additive segregates
to the
surface of the polyolefin film, where a lower refractive index region is
formed, which
enhances light scattering of the film as compared to films that are free of a
fluorochemical additive. Regardless of the particular fluorochemical additive
utilized, the fluorochemical additive can be present in the elastic film core
layer
144B in an amount ranging from about 0.1 wt.% to about 5 wt.%, such as from
about 0.5 wt.% to about 4wt.%, such as from about 1 wt.% to about 3 wt.% based
on the total weight of the elastic film core layer 144B. In one particular
embodiment,
the fluorochemical additive can be present in an amount of about 1.5 wt.%
based on
the total weight of the elastic film core layer 144B.
In one embodiment, the elastic film core layer 144B can also include a filler.
Fillers are particulates or other forms of material that may be added to the
film
polymer extrusion blend and that will not chemically interfere with the
extruded film,
but which may be uniformly dispersed throughout the film. Fillers may serve a
variety of purposes, including enhancing film opacity and/or breathability
(i.e., vapor-
permeable and substantially liquid-impermeable). For instance, filled films
may be
made breathable by stretching, which causes the polymer to break away from the
filler and create microporous passageways. Breathable microporous elastic
films
are described, for example, in U.S. Patent Nos. 5,932,497 to Morman, et al.,
5,997,981, 6,015,764, and 6,111,163 to McCormack, et al., and 6,461,457 to
Taylor,
et al., which are incorporated herein in their entirety by reference thereto
for all
purposes. Examples of suitable fillers include, but are not limited to,
calcium
carbonate, various kinds of clay, silica, alumina, barium carbonate, sodium
carbonate, magnesium carbonate, talc, barium sulfate, magnesium sulfate,
aluminum sulfate, zeolites, cellulose-type powders, kaolin, mica, carbon,
calcium
oxide, magnesium oxide, aluminum hydroxide, pulp powder, wood powder,
cellulose
derivatives, chitin and chitin derivatives. In one particular embodiment, the
filler in
the core layer 144B can include calcium carbonate, which can provide the
elastic
film 144, and thus the material 200, with light scattering and light absorbing
properties to help reduce glare, particularly after stretching the calcium
carbonate-
containing core layer 144B, which further increases the opacity and increases
the
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light scattering of the material 200. For instance, the calcium carbonate (or
any
other suitable filler) can have a refractive index ranging from about 1.60 to
about
1.72, such as from about 1.62 to about 1.70, such as from about 1.64 to about
1.68,
such as about 1.66, to impart the material 200 with the desired light
scattering and
light absorbing properties. In certain cases, the filler content of the film
may range
from about 50 wt.% to about 85 wt.%, in some embodiments, from about 55 wt.%
to
about 80 wt.%, and in some embodiments, from about 60 wt.% to about 75 wt.% of
the elastic film core layer 144B based on the total weight of the elastic film
core
layer 144B.
Further, the elastic film core layer 144B can also include one or more
pigments to help achieve the desired gray color of the gown 101. Examples of
suitable pigments include, but are not limited to, titanium dioxide (e.g., SCC
11692
concentrated titanium dioxide), zeolites, kaolin, mica, carbon black, calcium
oxide,
magnesium oxide, aluminum hydroxide, and combinations thereof. In certain
cases,
for instance, the elastic film core layer 144B can include titanium dioxide in
an
amount ranging from about 0.1 wt.% to about 10 wt.%, in some embodiments, from
about 0.5 wt.% to about 7.5 wt.%, and in some embodiments, from about 1 wt.%
to
about 5 wt.% based on the total weight of the core layer 144B. The titanium
dioxide
can have a refractive index ranging from about 2.2 to about 3.2, such as from
about
2.4 to about 3, such as from about 2.6 to about 2.8, such as about 2.76, to
impart
the material 200 with the desired light scattering and light absorbing
properties.
Further, the elastic film core layer 144B can also include carbon black in an
amount
ranging from about 0.1 wt.% to about 10 wt.%, in some embodiments, from about
0.5 wt.% to about 7.5 wt.%, and in some embodiments, from about 1 wt.% to
about
5 wt.% based on the total weight of the core layer 144B. The carbon black can
have
a refractive index ranging from about 1.2 to about 2.4, such as from about 1.4
to
about 2.2, such as from about 1.6 to about 2 to impart the material 200 with
the
desired light scattering and light absorbing properties. The elastic film core
layer
144B can also include a blue pigment in an amount ranging from about 0.1 wt.%
to
about 10 wt.%, in some embodiments, from about 0.5 wt.% to about 7.5 wt.%, and
in some embodiments, from about 1 wt.% to about 5 wt.% based on the total
weight
of the individual layer. The combination of the carbon black and blue pigment
improves the ability of the elastic film core layer 144B to absorb light.
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Further, like the elastic film core layer 144B, the elastic film skin layers
144A
and 144C that sandwich the elastic film core layer 144B can also be formed
from
one or more semi-crystalline polyolefins. Exemplary semi-crystalline
polyolefins
include polyethylene, polypropylene, blends and copolymers thereof. In one
particular embodiment, a polyethylene is employed that is a copolymer of
ethylene
and an a-olefin, such as a C3-C20 a-olefin or C3-C12 a-olefin. Suitable a-
olefins may
be linear or branched (e.g., one or more C1-C3 alkyl branches, or an aryl
group).
Specific examples include 1-butene; 3-methyl-1-butene; 3,3-dimethy1-1-butene;
1-
pentene; 1-pentene with one or more methyl, ethyl or propyl substituents; 1-
hexene
with one or more methyl, ethyl or propyl substituents; 1-heptene with one or
more
methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl
or
propyl substituents; 1-nonene with one or more methyl, ethyl or propyl
substituents;
ethyl, methyl or dimethyl-substituted 1-decene; 1-dodecene; and styrene.
Particularly desired a-olefin comonomers are 1-butene, 1-hexene and 1-octene.
The ethylene content of such copolymers may be from about 60 mole% to about 99
mole%, in some embodiments from about 80 mole% to about 98.5 mole%, and in
some embodiments, from about 87 mole% to about 97.5 mole%. The a-olefin
content may likewise range from about 1 mole% to about 40 mole%, in some
embodiments from about 1.5 mole% to about 15 mole%, and in some embodiments,
from about 2.5 mole% to about 13 mole%.
Particularly suitable polyethylene copolymers are those that are "linear" or
"substantially linear." The term "substantially linear" means that, in
addition to the
short chain branches attributable to comonomer incorporation, the ethylene
polymer
also contains long chain branches in the polymer backbone. "Long chain
branching"
refers to a chain length of at least 6 carbons. Each long chain branch may
have the
same comonomer distribution as the polymer backbone and be as long as the
polymer backbone to which it is attached. Preferred substantially linear
polymers
are substituted with from 0.01 long chain branch per 1000 carbons to 1 long
chain
branch per 1000 carbons, and in some embodiments, from 0.05 long chain branch
per 1000 carbons to 1 long chain branch per 1000 carbons. In contrast to the
term
"substantially linear", the term "linear" means that the polymer lacks
measurable or
demonstrable long chain branches. That is, the polymer is substituted with an
average of less than 0.01 long chain branch per 1000 carbons.
The density of a linear ethylene/a-olefin copolymer is a function of both the
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length and amount of the a-olefin. That is, the greater the length of the a-
olefin and
the greater the amount of a-olefin present, the lower the density of the
copolymer.
Although not necessarily required, linear polyethylene "plastomers" are
particularly
desirable in that the content of a-olefin short chain branching content is
such that
5 the ethylene copolymer exhibits both plastic and elastomeric
characteristics ¨ i.e., a
"plastomer." Because polymerization with a-olefin comonomers decreases
crystallinity and density, the resulting plastomer normally has a density
lower than
that of a polyethylene thermoplastic polymer (e.g., LLDPE), which typically
has a
density (specific gravity) of from about 0.90 grams per cubic centimeter
(g/cm3) to
10 about 0.94 g/cm3, but approaching and/or overlapping that of an
elastomer, which
typically has a density of from about 0.85 g/cm3 to about 0.90 g/cm3,
preferably from
0.86 to 0.89. For example, the density of the polyethylene plastomer may be
0.91
g/cm3 or less, in some embodiments from about 0.85 g/cm3 to about 0.90 g/cm3,
in
some embodiments, from 0.85 g/cm3 to 0.88 g/cm3, and in some embodiments,
15 from 0.85 g/cm3 to 0.87 g/cm3. Despite having a density similar to
elastomers,
plastomers generally exhibit a higher degree of crystallinity, are relatively
non-tacky,
and may be formed into pellets that are non-adhesive-like and relatively free
flowing.
Preferred polyethylenes for use in the present invention are ethylene-based
copolymer plastomers available under the designation EXACTTm from ExxonMobil
20 Chemical Company of Houston, Texas. Other suitable polyethylene
plastomers are
available under the designation ENGAGE TM and AFFINITYTm from Dow Chemical
Company of Midland, Michigan. An additional suitable polyethylene-based
plastomer is an olefin block copolymer available from Dow Chemical Company of
Midland, Michigan under the trade designation INFUSETM, which is an
elastomeric
25 copolymer of polyethylene. Still other suitable ethylene polymers are
low density
polyethylenes (LDPE), linear low density polyethylenes (LLDPE) or ultralow
linear
density polyethylenes (ULDPE), such as those available from The Dow Chemical
Company under the designations ASPUNTM (LLDPE), DOWLEXTM (LLDPE) and
ATTANETm (ULDPE). Other suitable ethylene polymers are described in U.S.
30 Patent Nos. 4,937,299 to Ewen, et al., 5,218,071 to Tsutsui et al.,
5,272,236 to Lai
et al., and 5,278,272 to Lai et al., which are incorporated herein in their
entirety by
reference thereto for all purposes.
Of course, the elastic film skin layers 144A and 144C of the present invention
are by no means limited to ethylene polymers. For instance, propylene
plastomers
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may also be suitable for use in the film. Suitable plastomeric propylene
polymers
may include, for instance, polypropylene homopolymers, copolymers or
terpolymers
of propylene, copolymers of propylene with an a-olefin (e.g., C3-C20)
comonomer,
such as ethylene, 1-butene, 2-butene, the various pentene isomers, 1-hexene, 1-
octene, 1-nonene, 1-decene, 1-unidecene, 1-dodecene, 4-methyl-1-pentene, 4-
methyl-1-hexene, 5-methyl-1-hexene, vinylcyclohexene, styrene, etc. The
comonomer content of the propylene polymer may be about 35 wt.% or less, in
some embodiments from about 1 wt.% to about 20 wt.%, in some embodiments
from about 2 wt.% to about 15 wt.%, and in some embodiments from about 3 wt.%
to about 10 wt.%. The density of the polypropylene (e.g., propylene/a-olefin
copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in some
embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3
to 0.91 g/cm3. In one particular embodiment, the elastic film skin layers 144A
and
144C can include a copolymer of polypropylene and polyethylene. The
polypropylene can have a refractive index ranging from about 1.44 to about
1.54,
such as from about 1.46 to about 1.52, such as from about 1.48 to about 1.50,
such
as about 1.49, while the polyethylene can have a refractive index ranging from
about 1.46 to about 1.56, such as from about 1.48 to about 1.54, such as from
about
1.50 to about 1.52, such as about 1.51, to impart the material 200 with the
desired
light scattering and light absorbing properties.
Suitable propylene polymers are commercially available under the
designations VISTAMAXXTm (e.g., 6102), a propylene-based elastomer from
ExxonMobil Chemical Co. of Houston, Texas; FINATM (e.g., 8573) from Atofina
Chemicals of Feluy, Belgium; TAFMERTm available from Mitsui Petrochemical
Industries; and VERSIFYTM available from Dow Chemical Co. of Midland,
Michigan.
Other examples of suitable propylene polymers are described in U.S. Patent
Nos.
5,539,056 to Yang, et al., 5,596,052 to Resconi, et al., and 6,500,563 to
Datta et
at, which are incorporated herein in their entirety by reference thereto for
all
purposes.
Any of a variety of known techniques may generally be employed to form the
semi-crystalline polyolefins. For instance, olefin polymers may be formed
using a
free radical or a coordination catalyst (e.g., Ziegler-Natta). Preferably, the
olefin
polymer is formed from a single-site coordination catalyst, such as a
metallocene
catalyst. Such a catalyst system produces ethylene copolymers in which the
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37
comonomer is randomly distributed within a molecular chain and uniformly
distributed across the different molecular weight fractions. Metallocene-
catalyzed
polyolefins are described, for instance, in U.S. Patent Nos. 5,272,236 to Lai
et al.,
5,322,728 to Davis et al., 5,472,775 to Obijeski et al., 5,571,619 to McAlpin
et al.,
and 6,090,325 to Wheat, et al., which are incorporated herein in their
entirety by
reference thereto for all purposes. Examples of metallocene catalysts include
bis(n-
butylcyclopentadienyl)titanium dichloride, bis(n-
butylcyclopentadienyl)zirconium
dichloride, bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconium
dichloride,
bis(methylcyclopentadienyl)titanium dichloride, bis(methylcyclopentadienyl)
zirconium dichloride, cobaltocene, cyclopentadienyltitanium trichloride,
ferrocene,
hafnocene dichloride, isopropyl(cyclopentadieny1,-1-flourenyl)zirconium
dichloride,
molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene,
titanocene dichloride, zirconocene chloride hydride, zirconocene dichloride,
and so
forth. Polymers made using metallocene catalysts typically have a narrow
molecular weight range. For instance, metallocene-catalyzed polymers may have
polydispersity numbers (Mw/Mn) of below 4, controlled short chain branching
distribution, and controlled isotacticity.
The melt flow index (MI) of the semi-crystalline polyolefins may generally
vary, but is typically in the range of about 0.1 grams per 10 minutes to about
100
grams per 10 minutes, in some embodiments from about 0.5 grams per 10 minutes
to about 30 grams per 10 minutes, and in some embodiments, about 1 to about 10
grams per 10 minutes, determined at 190 C. The melt flow index is the weight
of
the polymer (in grams) that may be forced through an extrusion rheometer
orifice
(0.0825-inch diameter) when subjected to a force of 5000 grams in 10 minutes
at
190 C, and may be determined in accordance with ASTM Test Method D1238-E.
In addition, it is noted that the elastic film skin layers 144A and 144C are
free
of the fluorochemical additive that is present in the elastic film core layer
144B. As a
result, the skin layers 144A and 144C have a higher refractive index than the
elastic
film core layer 144B, as the fluorochemical additive tends to lower the
refractive
index of the core layer 144B. The resulting difference in refractive indices
at the
interfaces between the core layer 144B and the skin layers 144A and 144C of
the
elastic film 144 is thought to enhance light scattering, which can result in a
high level
of opacity and a low level of light reflection (e.g., reduced glare).
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In any event, regardless of the number of layers present in the elastic film
144 and regardless of the specific polymer or polymers and additives used to
form
the elastic film 144, the elastic film 144 can have a basis weight ranging
from about
gsm to about 50 gsm, such as from about 10 gsm to about 40 gsm, such as from
5 about 15 gsm to about 30 gsm. In one particular embodiment, the elastic
film 144
can have a basis weight of about 20 gsm (about 0.6 osy).
The first material 200 also includes an SMS laminate 146 that is attached to
the skin layer 144C of the elastic film 144. One of the spunbond layers 146C
of the
SMS laminate 146 can form the inner-facing surface 204 of the first material
200 of
the gown 101, which is used to form the front panel 102 on the front 158 of
the gown
101, the sleeves 104 and the hood 178. Further, it is to be understood that
the
spunbond layer 146A, which is adjacent the skin layer 144C, the spunbond layer
146C, and the meltblown layer 146B disposed therebetween can be formed from
any of the polymers (e.g., polyolefins) mentioned above with respect to the
outer
spunbond layer 142. In other words, the SMS laminate 146 can be formed from
any
suitable polymer that provides softness, stretch, and pliability to the first
material
200.
In one particular embodiment, the SMS laminate 146 can include a first
spunbond layer 146A and a second spunbond layer 146C, where the spunbond
layers 146A and 146C can be formed from any suitable polymer that provides
softness, stretch, and pliability to the first material 200. For instance, the
spunbond
layers 146A and 146C can be formed from a semi-crystalline polyolefin.
Exemplary
polyolefins may include, for instance, polyethylene, polypropylene, blends and
copolymers thereof. In one particular embodiment, a polyethylene is employed
that
is a copolymer of ethylene and an a-olefin, such as a C3-C20 a-olefin or C3-
C12 a-
olefin. Suitable a-olefins may be linear or branched (e.g., one or more C1-C3
alkyl
branches, or an aryl group). Specific examples include 1-butene; 3-methyl-1-
butene; 3,3-dimethy1-1-butene; 1-pentene; 1-pentene with one or more methyl,
ethyl
or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl
substituents; 1-heptene with one or more methyl, ethyl or propyl substituents;
1-
octene with one or more methyl, ethyl or propyl substituents; 1-nonene with
one or
more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-
substituted 1-
decene; 1-dodecene; and styrene. Particularly desired a-olefin co-monomers are
1-
butene, 1-hexene and 1-octene. The ethylene content of such copolymers may be
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39
from about 60 mole% to about 99 mole%, in some embodiments from about 80
mole% to about 98.5 mole%, and in some embodiments, from about 87 mole% to
about 97.5 mole%. The a-olefin content may likewise range from about 1 mole%
to
about 40 mole%, in some embodiments from about 1.5 mole% to about 15 mole%,
and in some embodiments, from about 2.5 mole% to about 13 mole%.
The density of the polyethylene may vary depending on the type of polymer
employed, but generally ranges from 0.85 to 0.96 grams per cubic centimeter
("g/cm3"). Polyethylene "plastomers", for instance, may have a density in the
range
of from 0.85 to 0.91 g/cm3. Likewise, "linear low density polyethylene"
("LLDPE")
may have a density in the range of from 0.91 to 0.940 g/cm3; "low density
polyethylene" ("LDPE") may have a density in the range of from 0.910 to 0.940
g/cm3; and "high density polyethylene" ("HDPE") may have density in the range
of
from 0.940 to 0.960 g/cm3. Densities may be measured in accordance with ASTM
1505. Particularly suitable ethylene-based polymers for use in the present
invention
may be available under the designation EXACTTm from ExxonMobil Chemical
Company of Houston, Texas. Other suitable polyethylene plastomers are
available
under the designation ENGAGETM and AFFINITYTm from Dow Chemical Company
of Midland, Michigan. Still other suitable ethylene polymers are available
from The
Dow Chemical Company under the designations DOWLEXTM (LLDPE) and
ATTANETm (ULDPE). Other suitable ethylene polymers are described in U.S.
Patent Nos. 4,937,299 to Ewen et al.; 5,218,071 to Tsutsui et al.; 5,272,236
to Lai
et al.; and 5,278,272 to Lai et al., which are incorporated herein in their
entirety by
reference thereto for all purposes.
Of course, the spunbond layers 146A and 146C of the first material 200 are
.. by no means limited to ethylene polymers. For instance, propylene polymers
may
also be suitable for use as a semi-crystalline polyolefin. Suitable propylene
polymers may include, for instance, polypropylene homopolymers, as well as
copolymers or terpolymers of propylene with an a-olefin (e.g., C3-C20)
comonomer,
such as ethylene, 1-butene, 2-butene, the various pentene isomers, 1-hexene, 1-
octene, 1-nonene, 1-decene, 1-unidecene, 1-dodecene, 4-methyl-1-pentene, 4-
methyl-1-hexene, 5-methyl-1-hexene, vinylcyclohexene, styrene, etc. The
comonomer content of the propylene polymer may be about 35 wt.% or less, in
some embodiments from about 1 wt.% to about 20 wt.%, in some embodiments,
from about 2 wt.% to about 15 wt.%, and in some embodiments from about 3 wt.%
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to about 10 wt.%. The density of the polypropylene (e.g., propylene/a-olefin
copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in some
embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3
to 0.91 g/cm3. In one particular embodiment, the spunbond layers 146A and 146C
5 can each include a copolymer of polypropylene and polyethylene. The
polypropylene can have a refractive index ranging from about 1.44 to about
1.54,
such as from about 1.46 to about 1.52, such as from about 1.48 to about 1.50,
such
as about 1.49, while the polyethylene can have a refractive index ranging from
about 1.46 to about 1.56, such as from about 1.48 to about 1.54, such as from
about
10 .. 1.50 to about 1.52, such as about 1.51, to impart the material 200 with
the desired
light scattering and light absorbing properties.
Suitable propylene polymers are commercially available under the
designations VISTAMAXXTm from ExxonMobil Chemical Co. of Houston, Texas;
FINATM (e.g., 8573) from Atofina Chemicals of Feluy, Belgium; TAFMERTm
available
15 .. from Mitsui Petrochemical Industries; and VERSIFYTM available from Dow
Chemical
Co. of Midland, Michigan. Other examples of suitable propylene polymers are
described in U.S. Patent No. 6,500,563 to Datta, et al.; 5,539,056 to Yang, et
al.;
and 5,596,052 to Resconi, et al., which are incorporated herein in their
entirety by
reference thereto for all purposes.
20 Any of a variety of known techniques may generally be employed to form
the
polyolefins. For instance, olefin polymers may be formed using a free radical
or a
coordination catalyst (e.g., Ziegler-Natta or metallocene). Metallocene-
catalyzed
polyolefins are described, for instance, in U.S. Patent Nos. 5,571,619 to
McAlpin et
at; 5,322,728 to Davis et al.; 5,472,775 to Obijeski et al.; 5,272,236 to Lai
et al.; and
25 6,090,325 to Wheat, et al., which are incorporated herein in their
entirety by
reference thereto for all purposes.
The melt flow index (MI) of the polyolefins may generally vary, but is
typically
in the range of about 0.1 grams per 10 minutes to about 100 grams per 10
minutes,
in some embodiments from about 0.5 grams per 10 minutes to about 30 grams per
30 10 minutes, and in some embodiments, about 1 to about 10 grams per 10
minutes,
determined at 190 C. The melt flow index is the weight of the polymer (in
grams)
that may be forced through an extrusion rheometer orifice (0.0825-inch
diameter)
when subjected to a force of 2160 grams in 10 minutes at 190 C, and may be
determined in accordance with ASTM Test Method D1238-E.
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In addition to a polyolefin, the spunbond layers 146A and 146C can each
include a slip additive to enhance the softness of the spunbond layers 146A
and
146C. The slip additive can also reduce the glare of the first material 200 in
the
operating room by reducing the light reflectance of the first material and can
also
render the first material 200 more opaque than the standard gown material when
contacted with fats and lipids during surgery, where the standard gown
material
turns transparent upon contact with fats and lipids, which can result in the
wearer
having some concern that the barrier properties of a standard gown have been
compromised.
Variants of fatty acids can be used as slip additives. For example, the slip
additive can be erucamide, oleamide, stearamide, behenamide, oleyl
palmitamide,
stearyl erucamide, ethylene bis-oleamide, N,N'-Ethylene Bis(Stearamide) (EBS),
or
a combination thereof. Further, the slip additive have a refractive index
ranging
from about 1.42 to about 1.52, such as from about 1.44 to about 1.50, such as
from
about 1.46 to about 1.48, such as about 1.47, to impart the material 200 with
the
desired light scattering and light absorbing properties by reducing the
refractive
index. The slip additive can be present in each of the first spunbond layer
146A and
the second spunbond layer 146C in an amount ranging from about 0.25 wt.% to
about 6 wt.%, such as from about 0.5 wt.% to about 5 wt.%, such as from about
1
wt.% to about 4 wt.% based on the total weight of the particular spunbond
layer
146A or 146C. In one particular embodiment, the slip additive can be present
in an
amount of about 2 wt.% based on the total weight of the particular spunbond
layer
146A or 146C.
In addition to the polyolefin and slip additive, the spunbond layers 146A and
146C can also include one or more pigments to help achieve the desired gray
color
of the gown 101. Examples of suitable pigments include, but are not limited
to,
titanium dioxide (e.g., SCC 11692 concentrated titanium dioxide), zeolites,
kaolin,
mica, carbon black, calcium oxide, magnesium oxide, aluminum hydroxide, and
combinations thereof. In certain cases, for instance, each of the spunbond
layers
146A or 146C can include titanium dioxide in an amount ranging from about 0.1
wt.% to about 10 wt.%, in some embodiments, from about 0.5 wt.% to about 7.5
wt.%, and in some embodiments, from about 1 wt.% to about 5 wt.% based on the
total weight of the particular spunbond layer 146A or spunbond layer 146C. The
titanium dioxide can have a refractive index ranging from about 2.2 to about
3.2,
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such as from about 2.4 to about 3, such as from about 2.6 to about 2.8, such
as
about 2.76, to impart the material 200 with the desired light scattering and
light
absorbing properties. Further, each of the spunbond layers 146A or 146C can
also
include carbon black in an amount ranging from about 0.1 wt.% to about 10
wt.%, in
some embodiments, from about 0.5 wt.% to about 7.5 wt.%, and in some
embodiments, from about 1 wt.% to about 5 wt.% based on the total weight of
the
particular spunbond layer 146A or spunbond layer 146C. The carbon black can
have a refractive index ranging from about 1.2 to about 2.4, such as from
about 1.4
to about 2.2, such as from about 1.6 to about 2 to impart the material 200
with the
desired light scattering and light absorbing properties. In addition, each of
the
spunbond layers 146A or 146C can also include a blue pigment in an amount
ranging from about 0.1 wt.% to about 10 wt.%, in some embodiments, from about
0.5 wt.% to about 7.5 wt.%, and in some embodiments, from about 1 wt.% to
about
5 wt.% based on the total weight of the individual layer. The combination of
the
carbon black and blue pigment improves the ability of the spunbond layers 146A
or
146C to absorb light.
The meltblown layer 146B of the spunbond-meltblown-spunbond second
material 300 can also be formed from any of the semi-crystalline polyolefins
discussed above with respect to the first spunbond layer 146A and the second
spunbond layer 146C of the first material 200. In one particular embodiment,
the
meltblown layer 146B can be formed from 100% polypropylene.
Regardless of the specific polymer or polymers and additives used to form
the SMS laminate 146, the SMS laminate 146 can have a basis weight ranging
from
about 5 gsm to about 50 gsm, such as from about 10 gsm to about 40 gsm, such
as
from about 15 gsm to about 30 gsm. In one particular embodiment, the SMS
laminate 146 can have a basis weight of about 22 gsm (about 0.65 osy).
Despite the use of a front panel 102, sleeves 104, and hood 178 (e.g., all of
the hood 178 or at least the first portion 256 of the hood 178 as described
above)
that are formed from an air impermeable but moisture-vapor breathable first
material
200, the amount of heat that becomes trapped can be uncomfortable to the
wearer.
As such, the present inventor has discovered that the placement of a highly
breathable and air permeable first rear panel 120 and second rear panel 120
formed
from a second material 300 in the rear 160 of the gown 101 can facilitate the
dissipation of trapped humidity and heat between the gown 101 and the wearer.
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Further, in some embodiments, a second portion 258 of the hood 178 below seam
254 at the rear 160 of the gown 101 can optionally be formed from the second
material 300.
In one particular embodiment, the second material 300 can be in the form of
a spunbond-meltblown-spunbond (SMS) laminate that has enhanced air
breathability in order to facilitate removal of trapped heated air and
moisture from
the gown 101. For instance, the second material 300 allows for an air
volumetric
flow rate ranging from about 20 standard cubic feet per minute (scfm) to about
80
scfm, such as from about 30 scfm to about 70 scfm, such as from about 40 scfm
to
.. about 60 scfm, as determined at 1 atm (14.7 psi) and 20 C (68 F). In one
particular
embodiment, the second material 300 allows for an air volumetric flow rate of
about
45 scfm. Because the first rear panel 120, the second rear panel 122, and
lower or
second portion 256 of the hood 178 below seam 254 at the rear 160 of the gown
101 can be formed from the air breathable second material 300, the heat and
humidity that can build up inside the space between the gown 101 and the
wearer's
body can escape via convection and/or by movement of air as the movement of
the
gown materials 200 and 300 changes the volume of space between the gown 101
and the wearer's body. Further, the SMS laminate used to form the second
material
300 can have a basis weight ranging from about 20 gsm to about 80 gsm, such as
from about 25 gsm to about 70 gsm, such as from about 30 gsm to about 60 gsm.
In one particular embodiment, the second material 300 can have a basis weight
of
about 40 gsm (about 1.2 osy).
The various layers of the second material 300 are discussed in more detail
below.
The first spunbond layer 148 and second spunbond layer 152 of the second
material 300 can be formed from any suitable polymer that provides softness
and air
breathability to the second material 300. For instance, the first spunbond
layer 148
and the second spunbond layer 152 can be formed from a semi-crystalline
polyolefin. Exemplary polyolefins may include, for instance, polyethylene,
polypropylene, blends and copolymers thereof. In one particular embodiment, a
polyethylene is employed that is a copolymer of ethylene and an a-olefin, such
as a
C3-C20 a-olefin or C3-C12 a-olefin. Suitable a-olefins may be linear or
branched
(e.g., one or more C1-C3 alkyl branches, or an aryl group). Specific examples
include 1-butene; 3-methyl-1-butene; 3,3-dimethy1-1-butene; 1-pentene; 1-
pentene
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with one or more methyl, ethyl or propyl substituents; 1-hexene with one or
more
methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl
or
propyl substituents; 1-octene with one or more methyl, ethyl or propyl
substituents;
1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl
or
dimethyl-substituted 1-decene; 1-dodecene; and styrene. Particularly desired a-
olefin co-monomers are 1-butene, 1-hexene and 1-octene. The ethylene content
of
such copolymers may be from about 60 mole% to about 99 mole%, in some
embodiments from about 80 mole% to about 98.5 mole%, and in some
embodiments, from about 87 mole% to about 97.5 mole%. The a-olefin content
may likewise range from about 1 mole% to about 40 mole%, in some embodiments
from about 1.5 mole% to about 15 mole%, and in some embodiments, from about
2.5 mole% to about 13 mole%.
The density of the polyethylene may vary depending on the type of polymer
employed, but generally ranges from 0.85 to 0.96 grams per cubic centimeter
("g/cm3"). Polyethylene "plastomers", for instance, may have a density in the
range
of from 0.85 to 0.91 g/cm3. Likewise, "linear low density polyethylene"
("LLDPE")
may have a density in the range of from 0.91 to 0.940 g/cm3; "low density
polyethylene" ("LDPE") may have a density in the range of from 0.910 to 0.940
g/cm3; and "high density polyethylene" ("HDPE") may have density in the range
of
from 0.940 to 0.960 g/cm3. Densities may be measured in accordance with ASTM
1505. Particularly suitable ethylene-based polymers for use in the present
invention
may be available under the designation EXACTTm from ExxonMobil Chemical
Company of Houston, Texas. Other suitable polyethylene plastomers are
available
under the designation ENGAGETM and AFFINITYTm from Dow Chemical Company
of Midland, Michigan. Still other suitable ethylene polymers are available
from The
Dow Chemical Company under the designations DOWLEXTM (LLDPE) and
ATTANETm (ULDPE). Other suitable ethylene polymers are described in U.S.
Patent Nos. 4,937,299 to Ewen et al.; 5,218,071 to Tsutsui et al.; 5,272,236
to Lai
et al.; and 5,278,272 to Lai et al., which are incorporated herein in their
entirety by
reference thereto for all purposes.
Of course, the first spunbond layer 148 and the second spunbond layer 152
of the second material 300 are by no means limited to ethylene polymers. For
instance, propylene polymers may also be suitable for use as a semi-
crystalline
polyolefin. Suitable propylene polymers may include, for instance,
polypropylene
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homopolymers, as well as copolymers or terpolymers of propylene with an a-
olefin
(e.g., C3-C20) comonomer, such as ethylene, 1-butene, 2-butene, the various
pentene isomers, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-unidecene, 1-
dodecene, 4-methyl-1-pentene, 4-methyl-1-hexene, 5-methyl-1-hexene,
5 vinylcyclohexene, styrene, etc. The comonomer content of the propylene
polymer
may be about 35 wt.% or less, in some embodiments from about 1 wt.% to about
20
wt.%, in some embodiments, from about 2 wt.% to about 15 wt.%, and in some
embodiments from about 3 wt.% to about 10 wt.%. The density of the
polypropylene (e.g., propylene/a-olefin copolymer) may be 0.95 grams per cubic
10 centimeter (g/cm3) or less, in some embodiments, from 0.85 to 0.92
g/cm3, and in
some embodiments, from 0.85 g/cm3 to 0.91 g/cm3. In one particular embodiment,
the spunbond layers 148 and 152 can each include a copolymer of polypropylene
and polyethylene. The polypropylene can have a refractive index ranging from
about 1.44 to about 1.54, such as from about 1.46 to about 1.52, such as from
about
15 1.48 to about 1.50, such as about 1.49, while the polyethylene can have
a refractive
index ranging from about 1.46 to about 1.56, such as from about 1.48 to about
1.54,
such as from about 1.50 to about 1.52, such as about 1.51, to impart the
material
300 with the desired light scattering and light absorbing properties.
Suitable propylene polymers are commercially available under the
20 designations VISTAMAXXTm from ExxonMobil Chemical Co. of Houston, Texas;
FINATM (e.g., 8573) from Atofina Chemicals of Feluy, Belgium; TAFMERTm
available
from Mitsui Petrochemical Industries; and VERSIFYTM available from Dow
Chemical
Co. of Midland, Michigan. Other examples of suitable propylene polymers are
described in U.S. Patent No. 6,500,563 to Datta, et al.; 5,539,056 to Yang, et
al.;
25 and 5,596,052 to Resconi, et al., which are incorporated herein in their
entirety by
reference thereto for all purposes.
Any of a variety of known techniques may generally be employed to form the
polyolefins. For instance, olefin polymers may be formed using a free radical
or a
coordination catalyst (e.g., Ziegler-Natta or metallocene). Metallocene-
catalyzed
30 polyolefins are described, for instance, in U.S. Patent Nos. 5,571,619
to McAlpin et
at; 5,322,728 to Davis et al.; 5,472,775 to Obijeski et al.; 5,272,236 to Lai
et al.; and
6,090,325 to Wheat, et al., which are incorporated herein in their entirety by
reference thereto for all purposes.
The melt flow index (MI) of the polyolefins may generally vary, but is
typically
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in the range of about 0.1 grams per 10 minutes to about 100 grams per 10
minutes,
in some embodiments from about 0.5 grams per 10 minutes to about 30 grams per
minutes, and in some embodiments, about 1 to about 10 grams per 10 minutes,
determined at 190 C. The melt flow index is the weight of the polymer (in
grams)
5 that may be forced through an extrusion rheometer orifice (0.0825-inch
diameter)
when subjected to a force of 2160 grams in 10 minutes at 190 C, and may be
determined in accordance with ASTM Test Method D1238-E.
In addition to a polyolefin, the first spunbond layer 148 and the second
spunbond layer 152 can also include a slip additive to enhance the softness of
the
10 .. first spunbond layer 148 and the second spunbond layer 152. The slip
additive can
also reduce the coefficient of friction and increase the hydrohead of the
first
spunbond layer 148 and the second spunbond layer 152 of the first rear panel
120
and second rear panel 122. Such a reduction in the coefficient of friction
lessens
the chance of the gown 101 being cut or damaged due to abrasions and also
prevents fluids from seeping through the second material 300. Instead, at
least in
part due to the inclusion of the slip additive, fluid that contacts the outer-
facing
surface 302 of the gown 101 can remain in droplet form and run vertically to
the
distal end 156 of the gown 101 and onto the floor. The slip additive can also
reduce
the glare of the second material 300 in the operating room by reducing the
light
reflectance of the first material and can also render the second material 300
more
opaque than the standard gown material when contacted with fats and lipids
during
surgery, where the standard gown material turns transparent upon contact with
fats
and lipids, which can result in the wearer having some concern that the
barrier
properties of a standard gown have been compromised.
The slip additive can function by migrating to the surface of the polymer used
to form the first spunbond layer 148 and/or the second spunbond layer 152,
where it
can provide a coating that reduces the coefficient of friction of the outer-
facing
surface 302 and/or body-facing surface or inner-facing surface 304 of the
first
material 300. Variants of fatty acids can be used as slip additives. For
example, the
slip additive can be erucamide, oleamide, stearamide, behenamide, oleyl
palmitamide, stearyl erucamide, ethylene bis-oleamide, N,N'-Ethylene
Bis(Stearamide) (EBS), or a combination thereof. Further, the slip additive
can have
a refractive index ranging from about 1.42 to about 1.52, such as from about
1.44 to
about 1.50, such as from about 1.46 to about 1.48, such as about 1.47, to
impart the
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material 200 with the desired light scattering and light absorbing properties.
The slip
additive can be present in the first spunbond layer 148 and/or the second
spunbond
layer 152 of the second material 300 in an amount ranging from about 0.25 wt.%
to
about 6 wt.%, such as from about 0.5 wt.% to about 5 wt.%, such as from about
1
wt.% to about 4 wt.% based on the total weight of the first spunbond layer 148
and/or the second spunbond layer 152. In one particular embodiment, the slip
additive can be present in an amount of about 2 wt.% based on the total weight
of
the first spunbond layer 148 and/or the second spunbond layer 152.
In addition to the polyolefin and slip additive, the spunbond layers 148 and
152 can also include one or more pigments to help achieve the desired gray
color of
the gown 101. Examples of suitable pigments include, but are not limited to,
titanium dioxide (e.g., SCC 11692 concentrated titanium dioxide), zeolites,
kaolin,
mica, carbon black, calcium oxide, magnesium oxide, aluminum hydroxide, and
combinations thereof. In certain cases, for instance, each of the spunbond
layers
148 or 152 can include titanium dioxide in an amount ranging from about 0.1
wt.% to
about 10 wt.%, in some embodiments, from about 0.5 wt.% to about 7.5 wt.%, and
in some embodiments, from about 1 wt.% to about 5 wt.% based on the total
weight
of the particular spunbond layer 148 or 152. The titanium dioxide can have a
refractive index ranging from about 2.2 to about 3.2, such as from about 2.4
to about
3, such as from about 2.6 to about 2.8, such as about 2.76, to impart the
material
200 with the desired light scattering and light absorbing properties. Further,
each of
the spunbond layers 148 or 152 can also include carbon black in an amount
ranging
from about 0.1 wt.% to about 10 wt.%, in some embodiments, from about 0.5 wt.%
to about 7.5 wt.%, and in some embodiments, from about 1 wt.% to about 5 wt.%
based on the total weight of the particular spunbond layer 148 or spunbond
layer
152. The carbon black can have a refractive index ranging from about 1.2 to
about
2.4, such as from about 1.4 to about 2.2, such as from about 1.6 to about 2 to
impart
the material 300 with the desired light scattering and light absorbing
properties. In
addition, each of the spunbond layers 148 or 152 can also include a blue
pigment in
an amount ranging from about 0.1 wt.% to about 10 wt.%, in some embodiments,
from about 0.5 wt.% to about 7.5 wt.%, and in some embodiments, from about 1
wt.% to about 5 wt.% based on the total weight of the individual layer. The
combination of the carbon black and blue pigment improves the ability of the
spunbond layers 148 or 152 to absorb light.
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The meltblown layer 150 of the spunbond-meltblown-spunbond second
material 300 can also be formed from any of the semi-crystalline polyolefins
discussed above with respect to the first spunbond layer 148 and the second
spunbond layer 152 of the second material 300. In one particular embodiment,
the
meltblown layer 150 can be formed from 100% polypropylene.
The cuffs 106 and collar 110 (if present) of the disposable surgical gown 101
of the present invention can be formed from a woven or knit material that is
air
breathable, soft, and extensible. The collar 110 can also be water repellant.
In one
particular embodiment, the collar 110 and the cuffs 104 can be formed from a
knit
polyester. Because the material from which the collar 110 is formed is
extensible,
the collar 110 can stretch and conform to a wearer's particular neck
dimensions to
lay flat against the wearer's neck and prevent any gapping of the collar 110,
which
could allow bone fragments, blood splatter, and other biologic materials to
come into
contact with the wearer. In any event, the collar 110 can be sewn to the front
panel
102, sleeves 104, first rear panel 120, and second rear panel 122 with a
polyester
thread. Further, the cuffs 106 can be formed from the same material as the
collar
110, as discussed above. In addition, the cuffs 106 can be sewn to the sleeves
104
with a polyester thread.
In addition to the surgical gown 101 discussed above, it is also to be
understood that the personal protection and ventilation system 100 with which
the
visor system 180 of the present invention can be used can also include a
helmet
190 with an optional light source 188, an air tube 184, and a belt 206 with an
attached fan 182 and power source (e.g., battery 216) as described in detail
above
with reference to FIG. 9.
The present invention has been described both in general and in detail by
way of examples. These and other modifications and variations of the present
invention may be practiced by those of ordinary skill in the art, without
departing
from the spirit and scope of the present invention. In addition, it should be
understood that aspects of the various embodiments may be interchanged both in
whole or in part. Furthermore, those of ordinary skill in the art will
appreciate that
the foregoing description is by way of example only, and is not intended to
limit the
invention so further described in such appended claims.
