Note: Descriptions are shown in the official language in which they were submitted.
2j 8 5 715
SLIP-RESISTANT SHOE COVER
FIELD OF THE INVENTION
The present invention is directed to shoe covers and more
particularly, the present invention is directed to slip-
resistant shoe covers formed from nonwoven fabrics.
BACKGROUND OF THE INVENTION
As is generally known, protective garments, such as surgical
gowns, surgical drapes, and shoe covers (hereinafter
collectively "surgical articles") have been designed to greatly
reduce, if not prevent, the transmission through the surgical
article of liquids and/or airborne contaminants. In surgical
procedure environments, such liquid sources include the gown
wearer's perspiration, patient liquids, such as blood and life
support liquids such as plasma and saline. Examples of airborne
contaminants include, but are not limited to, biological
contaminants, such as bacteria, viruses and fungal spores. Such
contaminants may also incluoe particulate material such as, but
not limited to, lint, mineral fines, dust, skin squamae and
respiratory droplets.
Many of these surgical articles were originally made of
cotton or linen and were sterilized prior to their use in the
operating room. In many instances, surgical articles fashioned
from cotton or linen provide insufficient barrier protection
from the transmission therethrough of airborne contaminants.
Furthermore, these articles were costly, and, of course,
laundering and sterilization procedures were required before
reuse.
Disposable surgical articles, which also may require
sterilization prior to their use, have largely replaced linen
surgical articles. In some instances, such disposable surgical
articles may be formed from nonwoven porous materials such as
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spunbonded polypropylene or nonwoven laminates, such as
spunbond/meltblown/spunbond.
Some surgical articles, such as surgical gowns and drapes,
are generally designed to loosely fit or lie over the wearer.
While surgical gowns and drapes are subjected to some pulling
forces relative to the movement of the wearer, such gown and
drapes generally are not subjected to the load bearing forces
or abrupt pulling or shearing forces to which more form fitting
surgical articles, such as shoe covers, may be subjected. As
such, one challenge for the designers of form fitting surgical
articles, such as shoe covers, is to sufficiently secure the
seams in the fabric forming these articles such that these
articles may withstand such load bearing, pulling and/or
shearing forces. Furthermore, in the case of form fitting
surgical articles, the designer thereof is further challenged
to design effective, low-cost disposable surgical articles with
forming fitting features.
Additionally, in the case of shoe covers, it is not uncommon
for the operating room floor or hospital floors, which are
generally smooth by design, to become insulted with the above
described liquids which may be generated during a surgical
procedure. As such, shoe cover designers are also challenged to
design cost effective slip-resistant shoe covers.
Therefore, there is a need for shoe covers and methods for
making the same which provide improved fabric bonding, form
fitting and slip-resistant features. Such improved materials
and methods are provided by the present invention and will
become more apparent upon further review of the following
specification.
SUMMARY OF THE INVENTION
In response to the above problems encountered by those of
skill in the art, the present invention provides a disposable,
flexible shoe cover for receiving a sole of a shoe or a foot.
The shoe cover includes cleats secured to at least one surface
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of the shoe cover, wherein some of the cleats are adapted to
overlie the sole. The shoe cover may also include an elastic
member secured to an inside surface thereof, wherein said
elastic member is adapted to contact the sole.
In one embodiment, the cleats may include a first portion
and a second portion wherein, the second portion is thicker in
cross-section than the first portion. In another embodiment,
the first and second portions of the cleats are eccentrically
positioned.
In another embodiment, the shoe cover may include a pair of
panels. The panels are secured together near an area defined
by respective top and side edges with a pressure sensitive hot
melt adhesive. Additionally, portions of the respective side
edges between the pressure sensitive hot melt adhesive and a
bottom edge may be secured together by ultra sonic bonding.
This shoe cover may further include an elastic member ultra
sonically bonded to each panel near the top edge thereof and
another elastic member secured near the bottom edge of one of
the panels. Cleats may also be secured to at least one surface
of the shoe cover, wherein some of the cleats are adapted to
overlie the sole. These cleats may include a first portion and
a second portion wherein the second portion is thicker in
cross-section than the first portion. The first and second
portions may also be eccentrically positioned.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG.1 is a side plan view of the shoe cover of the present
invention.
FIG.2 is a plan view of a continuous sheet of material
illustrating a plurality of shoe cover cut-out patterns
overlaid by a repeating cleat pattern.
FIG.3 is a plan view of a shoe cover blank formed in
accordance with the cut-out pattern illustrated in FIG. 2.
FIG.4 is a cross-sectional view of the shoe cover blank
illustrated in FIG.3 taken along lines 4-4.
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FIG.5 is a cross-sectional view of FIG.6 taken along lines
5-5.
FIG.6 is another plan view of the shoe cover blank.
FIG.7 is a cross-sectional view of the shoe cover blank
taken along lines 5-5 of FIG.6 illustrating a folding step in
the process of forming the shoe cover.
FIG.8 is a side plan view of a folded shoe cover blank
folded in accordance with the folding step illustrated in
FIG.7.
FIG.9 is an enlarged view of a portion of the shoe cover of
FIG.8 illustrating a portion of the shoe cover and a cleat
pattern.
FIG.10 is a cross-sectional view of a portion of the shoe
cover taken along lines 10-10 of FIG.9 illustrating the cross-
sectional profile of several cleats. -
FIG.11 is an enlarged perspective view of one of the cleats
illustrated in FIG.10.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term "nonwoven fabric" refers to a
fabric that has a structure of individual fibers or filaments
which are interlaid, but not in an identifiable repeating
manner.
As used herein the term "spunbond fibers" refers to fibers
which are formed by extruding molten thermoplastic material as
filaments from a plurality of fine, usually circular
capillaries of a spinnerette with the diameter of the extruded
filaments then being rapidly reduced as by, for example, in
U.S. Patent no. 4,340,563 to Appel et al., and U.S. Patent no.
3,692,618 to Dorschner et al., U.S. Patent no. 3,802,817 to
Matsuki et al., U.S. Patent nos. 3,338,992 and 3,341,394 to
Kinney, U.S. Patent nos. 3,502,763 and 3,909,009 to Levy, and
U.S. Patent no. 3,542,615 to Dobo et al.
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As used herein the term "meltblown fibers" means fibers
formed by extruding a molten thermoplastic material through a
plurality of fine, usually circular, die capillaries as molten
threads or filaments into a high velocity, usually heated gas
(e.g. air) stream which attenuates the filaments of molten
thermoplastic material to reduce their diameter. Thereafter,
the meltblown fibers are carried by the high velocity gas
stream and are deposited on a collecting surface to form a
fabric of randomly disbursed ineltblown fibers. Meltblowing is
described, for example, in U.S. Patent no. 3,849,241 to Buntin,
U.S. Patent no. 4,307,143 to Meitner et al., and U.S. Patent
4,663,220 to Wisneski et al
Turning now to the drawings, FIG.1 illustrates a shoe cover
20. The shoe cover 20 includes a body 23 formed by a pair-of
panels 21 and 21'. The panels 21 and 21' include a top edge 22
and 22', respectively. The top edges 22 and 22' define an
opening 30 for receiving a sole (not shown) of a foot or a
shoe. The panels 21 and 21' are joined along a common bottom
edge 24 and side edges 26 and 28. Each panel 21 and 21'
includes an inside surface 32 and an outside surface 34.
The top edges 22 and 22' each include a strip of elastic
material described in greater detail below. In this way, the
opening 30 is expandable so as to be forming fitting about the
wearer's ankle. The bottom edge 24 is also made expandable by
securing another strip of elastic material near the bottom edge
24. In this way, the shoe cover 20 fits snugly about the toe
and heel portions of the sole. The shoe cover 20 further
includes seams 36 and 38 near the side edges 26 and 28,
respectively, formed by, for example, ultra sonic bonding the
respective portions of the panels 21 and 21'.
A traction pattern 40, formed by a plurality of cleats 41,
(described in greater detail below) is applied, such as by
printing, to the outer surface 34 of the shoe cover 20 near the
bottom edge 24. Desirably, the traction pattern 40 may be
applied to one or both panels, 21 and 21', generally near
bottom edge 24. So that sufficient tractional forces may be
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= formed between the operating room floor and the outside surface
34 of the shoe cover 20, the width and length dimensions of the
traction pattern 40 should be sufficient to overly a sufficient
portion of the sole (not shown) of either the wearer's foot or
shoe when the shoe cover 20 is worn. When the seams 36 and 38
are formed by ultra sonic bonding, it is desirable that the
traction pattern 40 not extend into the area of the shoe cover
20 defined by seams 36 or 38.
Similarly, so that sufficient tractional forces may be
formed between the inside surface 32 of the shoe cover 20 and
the sole (not shown) of either the wearer's foot or shoe, a
traction pattern 40' (FIG.2) may be applied to the inside
surface 32 of panels 21 and/or 21' near the bottom edge 24. The
traction pattern applied to the inside surface 32 may be
similar to the traction pattern 40 which is applied to the
outside surface 34.
FIGs. 2-8 illustrate several process steps for forming the
shoe cover 20 from a sheet of material 42, which may be a
continuous sheet of material, having sides 46 and 46'.
Referring now to FIG. 2, the sheet of material 42, suitable for
making the shoe cover 20, is provided with repeating shoe cover
cut-out patterns 44a, 44b and 44c. The side 46 of the material
42 will ultimately form the inside surface 32 of the shoe cover
20. As such, the traction pattern 40' on the side 46 of shoe
cover cut-out pattern 44b will ultimately reside on the inside
surface 32 of the shoe cover 20. Furthermore, the traction
pattern 40 on the side 46' of the shoe cover cut-out patterns
44a and 44c will ultimately reside on the outside surface 34 of
the shoe cover 20. It will be further understood that the
traction patterns, such as 40 and 40', may also be applied to
both sides, 46 and 46' of the material 42 so that both the
inside surface 32 and the outside surface 34 of the shoe cover
20 will be provided with a traction pattern.
Referring now to FIGs.3 and 4, there is illustrated a shoe
cover blank 48 formed by removing a portion of the material 42
along the shoe cover cut-out pattern 44b. So that other
structures may be more clearly illustrated, the traction
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pattern 40' is not illustrated in FIG.3. The shoe cover blank
48 includes generally parallel edges 50 and 50' and edge pairs
52 and 52' and 54 and 54'. Elastic members 56 and 56', such as
an elastic strips, are each secured generally parallel to and
near the respective edges 50 and 50' of the shoe cover blank
48. Another elastic member 58, such as and elastic strip, is
secured generally along and or parallel the center (illustrated
by center line A-A) of the shoe cover blank 48. The center line
A-A will ultimately form the bottom edge 24 of the shoe cover
20. The edges 52 and 52' will ultimately form the side edge 26
of the shoe cover 20 when the edges 52 and 52' are aligned and
united. Similarly, the edges 54 and 54' will ultimately form
the side edge 28 of the shoe cover 20 when the edges 54 and 54'
are aligned and united.
The elastic members 56, 56' and 58 may be formed from a
variety of elastic materials such as, for example, natural or
synthetic rubber, and polyester ether. Desirably, the elastic
members 56, 56' and 58 are formed from thermoplastic
polyurethane film. Such thermoplastic polyurethane film is
available from J.P. Stevens, catalogue no. MP-1882. The
dimension of these elastic members may be from between 1 to 20
mils thick and from between 1/4 inch to 3/4 inch in width.
When the shoe cover blank 48 is formed from a polyolef in
nonwoven material, such as a polypropylene nonwoven, desirably
the elastic members 56 and 56' may be secured to the nonwoven
material by ultra sonic bonding and the elastic member 58 may
be secured to the nonwoven material by use of an adhesive. By
use of ultra sonics and adhesives to bond these and other
components of the shoe cover 20, perforating, which inherently
occurs when using a sewing needle, of the shoe cover 20
material is avoided. Desirably, the adhesives used to secure
the elastic members to the shoe cover 20 may be an elastic
adhesive. An example of a commercially available elastic
adhesive is Findley Adhesive Company's (Milwaukee, WI)
catalogue no. H2096.
Desirably, the elastic members 56, 56' and 58 are tensioned,
such as be stretching in the length dimension, prior to being
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CA 02185715 2006-06-06
secured to the shoe cover blank 48 or material 42. As such, it
may be desirable to sufficiently tension the shoe cover blank
48 or a length of the material 42, such that the shoe cover
blank 48 or the material 42 is prevented from contracting once
the tensioned elastic members 56, 56' and 58 are secured
thereto. As such, it will be understood that it may be
desirable not to completely remove individual shoe cover blanks
48 from the material 42 if "in line" or continuous manufacture
of the shoe covers 20 is desired until all or substantially all
of the process steps illustrated in FIG.s 2-8 have been
completed.
Referring now to FIGS. 5 and 6, edges 60 and 60' are formed
by folding portions of the shoe cover blank 48 near the edges
50 and 50', respectively, over the elastic members 56 and 56'.
By folding the shoe cover blank 48 as just described and
illustrated, two three-layered structure 62 and 62' are formed.
Each three-layered structure 62 and 62' includes a shoe cover
blank layer, an elastic layer, and another shoe cover blank
layer (shoe cover/elastic/shoe cover).
It will be further noted that the edges 50 and 50' extend
beyond the elastic members 56 and 56'. The edges 60 and 60'
will ultimately form the top edges 22 and 22', respectively, of
the shoe cover 20. Once the elastic members 56 and 56' are
overlaid by a portion of the shoe cover blank 48 as previously
described and illustrated, it may be desirable to secure the
three-layered structures, 62 and 62' by ultra sonic bondinq. It
may be further desirable that the three layered structures, 62
and 62', be ultra-sonically bonded over their entire length as
opposed to spot bonding along the lengths thereof.
Referring now to FIG. 7 and FIG. 8 (now illustrating the
traction pattern 40), the shoe cover blank 48 (illustrated in
FIG.s 5 and 6) is folded along the center line A-A (FIGS. 6 and
8) in a direction indicated by arrows B and B' in FIG.7 such
that edges 60 and 60', 52 and 52' and 54 and 54' generally
align so as to form the panels 21 and 21'. Aligning edges 52
and 52' forms the side edge 26 and aligning edges 54 and 54'
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forms the side edge 28. The bottom edge 24 is formed by folding
the shoe cover blank 48 along the center line A-A.
A portion of the panels 21 and 21', illustrated by the
reference letter C, are secured at generally the intersection
of edges 60, 60' and with edges 52 and 52' by the application
of a pressure sensitive hot melt adhesive. Desirably, the
pressure sensitive hot melt adhesive may be applied by
spraying. It will be understood that the dimension of the
spray pattern of the hot melt adhesive applied to the portion
C may vary. However, it has been found that a spray pattern of
hot melt adhesive having a width at least sufficient to overlie
the material'between edges 60 and 50 or 60' and 50' (FIG.7),
and a length of about 1/2" to about 1", extending from the edge
pair 52/52' towards edge pair 54/54' to be sufficient.
The panels 21 and 21' may be further secured by ultra-
sonically bonding the portions of the edges 52 and 52' between
the pressure sensitive hot melt adhesive and the bottom edge
24. The width and length of the seam 36 formed by ultra-sonic
bonding may be varied by methods and techniques well known to
those skilled in the art. It is desirably that the material
bonded by the hot melt adhesive not be exposed to the ultra-
sonic bonding. In this way, over-bonding the hot melt adhesive
by ultra-sonic bonding is avoided. In those instances when the
hot melt adhesive is applied first followed by ultra-sonic
bonding, it has been observed that a stronger bond is created,
and particularly, when the shoe cover material formed from
nonwoven polypropylene, when the hot melt adhesive is not over-
bonded by ultra sonic bonding as opposed to over-bonding the
hot melt adhesive with ultra sonic bonding. However, ultra
sonic bonding followed by over-bonding with the hot melt
adhesive sufficiently bonds such materials.
A portion of the panels 21 and 21', illustrated by the
reference letter D are secured at generally the intersection of
edges 60, 60' and with edges 54 and 54' by the application of
a pressure sensitive hot melt adhesive. Desirably, the pressure
sensitive hot melt adhesive may be applied by spraying. It will
be understood that the dimension of the spray pattern of hot
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melt adhesive may vary. However, it has been found that a spray
pattern of hot melt adhesive having a width at least sufficient
to overlie the material between edges 60 and 50 or 60' and 50'
(FIG.7), and a length of about 1/2" to about 1", extending from
the edge pair 54/54' towards the edge pair 52/52' to be
sufficient.
The panels 21 and 21' may be further secured by ultra
sonically bonding the portions of the edges 54 and 54' between
the pressure sensitive hot melt adhesive and the bottom edge
24. As previously mentioned, the width and length of the seam
38 formed by ultra-sonic bonding may be varied by methods and
techniques well known to those skilled in the art. Similarly,
for the reason stated above, it is desirably that the material
bonded by the hot melt adhesive not be exposed to the ultra-
sonic bonding.
Furthermore, as previously mentioned, it is desirable that
the traction pattern not extend into the area of the panels 21
and 21' which are ultra-sonically bonded. Such areas include, for
example, seams 36 and 38. Extending the traction pattern into
these areas may result in fowling or damaging the ultra sonic
bonding equipment by the material used for forming the traction
pattern.
After securing the panels 21 and 21' as described above the
shoe covers 20 may be rolled in pairs and stored for future
use. It will be understood by those skilled in the art that
all of the-above described steps in the process of forming the
shoe cover 20 may be preformed in an "in-line" or continuous
manner.
Referring now to FIG. 9, a portion of the traction pattern
40 illustrated in FIG. 8 has been enlarged for clarity of
illustration. The traction pattern 40 includes a plurality of
individual and separate cleats 41. While the taction pattern
illustrated in FIG.s 8 and 9 may generally be described as
a series of repeating circles, it will be understood that other
35 traction patterns formed by a plurality of cleats 41 may be
suitable for purposes of the present invention and will be
readily appreciated by those skilled in the art. It will be
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further observed that some of the individual circles, such as
for example the circle 62, forming the traction pattern 40 have
no cleats 41 in the center 64. On the other hand, the center
of other circles, such as for example the circle 66, are
generally occupied by one or more of the cleats 41.
Referring now to FIGS. 10 and 11, FIG. 10 shows an enlarged
cross-sectional portion of the traction pattern 40 illustrated
in FIG. 9 and further illustrates several cleats 41 in cross
section. FIG. 11 is an enlarged perspective view of one of the
cleats 41. The cleats 41 are generally oval-shaped. However, it
will be understood that the cleats 41 may be formed into other
shapes, such as circular, elliptical, rod-shaped, rectangular,
square, trapezoid and the like. It will be further understood
that the traction pattern 40 may be formed from one or more of
such cleats 41 shapes.
Referring now to FIG.10, in cross-section, the cleats 41 may
generally be described as some what "foot-shaped" with a
thinned "toe" portion extending from a first end 71 along a
surface 75 of the cleat 41 towards a thicken "ankle" portion.
The ankle portion then terminating at a "heel" portion or
second end 73. The cleats 41 may also be generally described as
"L" shaped in cross-section. The cleats 41 may also be
described as having a first portion 68, corresponding to the
"toe" portion, and a second portion 70, corresponding to the
"ankle/heel" portion. The first portion 68 and the second
portion 70 are eccentrically positioned. The second portion 70 is
thicker in cross-section than the first portion 68 and
desirably, the thickest point of the second portion 70 is at
least twice as thick as the thickest point of the first portion
68.
The first portion 68 includes side walls 69 which extend
from the surface of shoe cover 20, such as the outside surface
34. While the thickness of the first portion 68 may vary, the
first portion 68 may further be generally described as planer
when viewed by the human eye unassisted by magnification. The
second portion 70 may further be generally described as dome-
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shaped and includes side walls 72 which extend from the first
portion 68 to an apex 74.
The transition from the first portion 68 to the second
portion 70 of the cleat 41 may generally be described as
seamless or continuous. More particularly, the transition from
the first portion 68 to the second portion 70 is perceptible,
by both sight and touch, along the area of the cleat 41 between
the first end 71 to the apex 74. This is so because of the
change in the slop of the surface 75 from the first portion 68
to the second portion 70 of the cleat 41 in an area generally
indicated by reference number 77. However, the transition from
the second portion 70 to the first portion 68 in the area of
the cleat 41 between the apex 74 and the second end 73 is
generally imperceptible, by both sight and touch. This is so
because there is little if any change in the slop between the
side wall 72 of the second portion 70 and the side wall 69 of
the first portion 68 between the apex 74 and the second end 73
(FIG.10).
With continued reference to FIG.10, the cleats 41 may
generally be selectively arranged within the traction pattern
40. One such arrangement of the cleats 41 may generally be
described as a "heel-toe" arrangement. In other words, for
example, when viewing the cleats 41 along the x-axis in FIG.10,
the second end 73 of one cleat 41 is nearer the first end 71 of
a following cleat 41 than the second end 73 of said following
cleat 41.
The eccentric positioning of the first and second portions,
70 and 72, respectively in combination with the flexibility of
the material forming the shoe cover 20, described in greater
below, provides the cleat 41 with at least two contacting
surfaces for contacting a support structure, such as a floor,
when the shoe cover 20 is worn. The contacting surfaces of the
cleats 41 may, for example, contact a floor, such as an
operating room floor, or the sole of the wearer's shoe,
depending upon whether the cleat 41 is secured to the outside
surface 34 or the inside surface 32 of the shoe cover 20 or
both.
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The first contacting surface of the cleat 41 is generally in
the area of and may include the apex 74. The second contacting
surface of the cleat 41 is in an area of the first portion 68
generally illustrated by reference numeral 76. The area 76 is
generally spaced a distance from the second portion 70. It will
also be appreciated that the cleats 41 may be sufficiently
spaced apart on the surface of the shoe cover 20 such that the
surface of the shoe cover 20 between the cleats 41 may contact
a supporting structure, such as a floor, when the cleat 41 is
in contact with such supporting structure. Alternatively, the
cleats 41 may be sufficiently spaced apart on the surface of
the shoe cover 20 such that the surface of the shoe cover 20
between the cleats 41 does not contact a supporting structure,
such as a f loor, when the cleat 41 is in contact with such
supporting structure.
The cleats 41 and the traction pattern 40 may be
selectively printed on to one or more of the surfaces of the
shoe cover 20. Desirable, the cleats 41 and traction pattern
40 are printed on the shoe cover by the gravure process or
screen printer, both of which are well known by those skilled
in the art. Particularly, the gravure process may desirably be
preformed on a printing apparatus of the kind manufactured by
the ITW Dynatech Company of Hendersonville, TN. It will be
further understood that the print wheel of such a printing
apparatus may be fitted with various patterns. As such, various
traction patterns and cleat dimensions may be achieved by
varying the print wheel pattern, the speed of the print wheel
and/or the line speed or entry speed of the shoe cover material
at the print wheel.
When the cleats 41 are formed by printing, it is desirable
that the cleat forming material be a hot melt material.
Suitable examples of cleat forming material include: Swift 84-
123 or 84-193 which are formed from vinyl acetate and paraffin
wax and are products of Swift adhesives, a Division of
Reichhold Chemicals, Inc. of Illinois and Findley's catalogue
no. 222-237 or 795-334 which are also vinyl acetate based hot
melt materials.
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The shoe cover 20 may be formed from a variety of fabrics
such as woven and nonwoven fabrics. Polymers are well suited
for the formation of fabrics, both woven and nonwoven, which
are useful in the practice of the present invention. Nonwoven
fabrics can be made from a variety of processes including, but
not limited to, air laying processes, wet laid processes,
hydroentangling processes, spunbonding, meltblowing, staple
fiber carding and bonding, and solution spinning. The fibers
themselves can be made from a variety of dielectric materials
including, but not limited to, polyesters, polyolefins, nylons
and copolymers of these materials. The fibers may be
relatively short, staple length fibers, typically less than 3
inches, or longer more continuous fibers such as are typically
produced by a spunbonding process.
The fabrics of the present invention may be formed from a
single layer or multiple layers. In the case of multiple
layers, the layers are generally positions in a juxtaposed or
surface-to-surface relationship and all or a portion of the
layers may be bound to adjacent layers.
It has been found that nonwoven fabrics formed from
thermoplastic based fibers and desirable polyolefin-based
fibers are well-suited for the above applications. Examples of
such fibers include spunbond fibers and meltblown fibers.
Examples of such nonwoven fabrics formed from such fibers are
the polypropylene nonwoven fabrics produced by the Assignee of
record, Kimberly-Clark Corporation.
In one embodiment, the nonwoven laminate may include at
least one ply formed from spunbond fibers and another ply
formed from meltblown fibers, such as a spunbond/meltblown (SM)
nonwoven laminate. In another embodiment, the nonwoven
laminate may include at least one ply formed from meltblown
fibers which is positioned between two plies formed from
spunbond fibers, such as a spunbond/meltblown/spunbond (SMS)
nonwoven laminate. Examples of these nonwoven laminates are
disclosed in U.S. Patent no. 4,041,203 to Brock et al., U.S.
Patent no. 5,169,706 to Collier, et al, and U.S. Patent no.
4,374,888 to Bornslaeger.
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It should be noted, however, that materials other
than nonwovens may be used. Examples of such other materials
include wovens, films, foam/film laminates and combinations
hereof, with and without nonwovens, may be used in the present
invention, such as for example a spunbond/film/spunbond (SFS)
laminate.
The spunbond fibers may be formed from polypropylene.
Suitable polypropylene for the spunbond layers are commercially
available as PD-9355 from the Exxon Chemical Company of
Baytown, Texas.
The meltblown fibers may be formed from polyolef in polymers,
such as polypropylene and polybutylene or a blend thereof.
Examples of such meltblown fibers are contained in U.S. Patents
5,165,979 and 5,204,174.
Desirably, the meltblown fibers may be formed from
a blend of polypropylene and polybutylene wherein the
polybutylene is present in the blend in a range from 0.5 to 20
weight percent of the blend. One such suitable polypropylene
is designated 3746-G from the Exxon Chemical Co., Baytown,
Texas. One such suitable polybutylene is available as DP-8911
from the Shell Chemical Company of Houston, Texas. The
meltblown fibers may also contain a polypropylene modified
according to U.S. patent 5,213,881.
The SMS nonwoven laminate may be made by sequentially
depositinq onto a moving forming belt first a spunbond ply,
then a meltblown ply and last another spunbond ply and then
bonding the plies together to form the laminate. Alternatively,
the plies may be made individually, collected in rolls, and
combined in a separate bonding step. Such SMS nonwoven
laminates usually have a basis weight of from about 0.1 to 12
ounces per square yard (osy) (3 to 400 grams per square meter
(gsm)), or more desirably from about 0.75 to about 5 osy (25 to
170 gsm) and still more desirably from about 0.75 to about 3
osy (25 to 100 gsm).
While the invention has been described in detail with
respect to specific embodiments thereof, it will be appreciated
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that those skilled in the art, upon attaining an understanding
of the foregoing, may readily conceive of alterations to,
variations of and equivalents to these embodiments.
Accordingly, the scope of the present invention should be
assessed as that of the appended claims and any equivalents
thereto.
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