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Patent 2661816 Summary

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(12) Patent Application: (11) CA 2661816
(54) English Title: THERMAL IMPULSE BONDING OF THERMALLY SENSITIVE LAMINATE BARRIER MATERIALS
(54) French Title: SOUDURE PAR IMPULSIONS THERMIQUES DE MATERIAUX BARRIERES STRATIFIES THERMOSENSIBLES
Status: Deemed Abandoned and Beyond the Period of Reinstatement - Pending Response to Notice of Disregarded Communication
Bibliographic Data
(51) International Patent Classification (IPC):
  • A41D 13/12 (2006.01)
  • A41D 27/24 (2006.01)
(72) Inventors :
  • LAWSON, MARY KATHERINE (United States of America)
  • MATHIS, MICHAEL P. (United States of America)
  • ROTELLA, JOHN ANTHONY (United States of America)
(73) Owners :
  • KIMBERLY-CLARK WORLDWIDE, INC.
(71) Applicants :
  • KIMBERLY-CLARK WORLDWIDE, INC. (United States of America)
(74) Agent: BORDEN LADNER GERVAIS LLP
(74) Associate agent:
(45) Issued:
(86) PCT Filing Date: 2007-07-03
(87) Open to Public Inspection: 2008-03-06
Availability of licence: N/A
Dedicated to the Public: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/IB2007/052602
(87) International Publication Number: WO 2008026090
(85) National Entry: 2009-02-25

(30) Application Priority Data:
Application No. Country/Territory Date
11/512,455 (United States of America) 2006-08-30

Abstracts

English Abstract

Thermal impulse heat welding, or "bar sealing", is used to bond thermally sensitive laminate barrier materials such that they will pass AAMI level 4 testing (ASTM 1670 and 1671 -b). In bar sealing, overlapping layers of thermally sensitive laminate barrier materials are melted and fused together to create a substantially solid bond at and/or adjacent the surface. No substantially un-melted areas remain within the fused bond area on the surface.


French Abstract

Selon l'invention, le soudage par impulsions thermiques ou 'soudage avec barrette chauffée' permet de souder des matériaux barrières stratifiés thermosensibles de sorte qu'ils obtiennent des résultats positifs à l'essai AAMI de niveau 4 (ASTM 1670 et 1671 -b). Dans le soudage avec barrette chauffée, des couches se chevauchant de matériaux barrières stratifiés thermosensibles sont fondues et fusionnées pour former une soudure sensiblement solide au niveau de la surface et/ou adjacente à celle-ci. Il ne reste aucune partie sensiblement non fondue dans la zone de soudure fusionnée de la surface.

Claims

Note: Claims are shown in the official language in which they were submitted.


WHAT IS CLAIMED IS:
1 A surgical gown having an AAMI critical zone comprising a tie cord bar
sealed
to said gown at a bond in said critical zone wherein said bond passes AAMI
level 4 testing.
2 The gown of claim 1 wherein said bond is made at a temperature between 240
and 320 °F (116 and 160 °C), a pressure between 40 and 80 psi
(276 and 552
kPa) and a dwell time between 0 and 5 seconds.
3 The gown of claim 1 wherein said bond is made at a temperature between 260
and 290 °F (127 and 143 °C), a pressure between 50 and 60 psi
(345 and 414
kPa) and a dwell time between 1 and 3 seconds.
4 The gown of claim 1 wherein said gown comprises a polyolefin microfiber
layer.
The gown of claim 4 wherein said gown further comprises a filled film.
6 A surgical gown having a tie cord and a tie cord bond area where said tie
cord
is bonded to said gown, wherein said tie cord bond area passes ASTM test
1671-b.
7 A thermal bond for a film layer-containing thermoplastic fabric wherein said
bond joins a thermoplastic material to said fabric to form a fused bonded
area,
without bonding to said film layer.
8 The bond of claim 7 wherein no un-melted areas remain within the fused bond
area on the surface.
9 The bond of claim 7 wherein said film layer-containing thermoplastic fabric
further comprises a filler within said film layer.
The bond of claim 7 wherein said thermal bond is produced substantially at or
adjacent a surface of the film layer-containing thermoplastic fabric while
avoiding degradation of said film layer in an interior region of said fabric.
11 The bond of claim 7 wherein said thermal bond has a width of between 0.32
and 1.75 cm.
12 The bond of claim 11 wherein said thermal bond has a length of between 2.54
and 76 cm.
13 The bond of claim 7 wherein said film layer-containing thermoplastic fabric
is a
spunbond/film laminate.
14

14 The bond of claim 13 wherein said spunbond layer is made from polyethylene,
polypropylene or an ethylene-propylene copolymer.
15 The bond of claim 13 wherein said film layer is a stretch-thinned film.
16 The bond of claim 15 wherein said film layer further comprises calcium
carbonate.
17 The bond of claim 15 wherein said film is a an ABA film.
18 The bond of claim 17 wherein said film is heated to a temperature no higher
than 5 degrees °C. below the melting point of the B layer in the film.
19 The bond of claim 18 wherein said film is stretched to about 250% to 500%.
of its unstretched length.
20 The bond of claim 18 wherein said film is stretched to about 300% of its
unstretched length.

Description

Note: Descriptions are shown in the official language in which they were submitted.


CA 02661816 2009-02-25
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THERMAL IMPULSE BONDING OF THERMALLY SENSITIVE LAMINATE
BARRIER MATERIALS
BACKGROUND OF THE INVENTION
Surgeons and other healthcare providers often wear an over garment during
operating procedures in order to enhance the sterile condition in the
operating
room and to protect the wearer. The over garment is typically a gown that has
a
main body portion to which sleeves and a tie cord are attached. The tie cord
encircles the wearer at the waist to keep the gown in place. In order to
prevent the
spread of infection to and from the patient, the surgical gown prevents bodily
fluids
and other liquids present during surgical procedures from flowing through the
gown.
Surgical gowns were originally made of cotton or linen, were reusable and
were sterilized prior to each use in the operating room. A disadvantage of the
materials used in these types of gowns is that they tend to form lint, which
is
capable of becoming airborne or clinging to the clothes of the wearer, thereby
providing another potential source of contamination. Additionally, costly
laundering
and sterilization procedures were required before reuse.
Disposable surgical gowns have largely replaced the reusable linen
surgical gown and many are now made in part or entirely from fluid repellent
or
impervious fabrics to prevent liquid penetration or "strike through". Various
materials and designs have been used in the manufacture of surgical gowns to
prevent contamination in different operating room conditions. Surgical gowns
are
now available in a variety of different levels of imperviousness and comfort.
Gowns made from completely impervious material provide a high degree of
protection, though a surgical gown constructed of this type of material is
typically
heavy, expensive, and uncomfortably hot to the wearer. In some surgical gowns,
certain portions such as the shoulders and back panels may be of a lighter
weight
material in order to provide for better breathability and help reduce the
overall
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weight of the gown. Generally, however, the higher the breathability of the
material, the lower the repellency of the material.
Different types of surgical procedures expose the healthcare provider to
different levels of blood and/or fluid exposure, so it is not feasible or
economical to
use the same type of surgical gown for every surgical procedure conducted by
the
healthcare provider. New guidelines have recently been created for the rating
of
the imperviousness of surgical gowns, gloves and the like, to provide guidance
to
healthcare providers. The Association for the Advancement of Medical
Instrumentation (AAMI) has proposed a uniform classification system for gowns
and drapes based on their liquid barrier performance. These procedures were
adopted by the American National Standards Institute (ANSI) and were recently
published as ANSIA/AAMI PB70: 2003 entitled Liquid Barrier Performance and
Classification of Protective Apparel and Drapes Intended for Use in Health
Care
Facilities, which was formally recognized by the U.S. Food and Drug
Administration in October, 2004. This standard established four levels of
barrier
protection for surgical gowns and drapes. The requirements for the design and
construction of surgical gowns are based on the anticipated location and
degree of
liquid contact, given the expected conditions of use of the gowns. The highest
level of imperviousness is AAMI level 4, used in "critical zones" where
exposure to
blood or other bodily fluids is most likely and voluminous. The AAMI standards
define "critical zones" as the front of the gown, including the tie cord
attachment
area, and the sleeves and sleeve seam area up to about 2 inches (5 cm) above
the elbow.
The main body portion and the sleeves of a surgical gown are usually
produced separately and joined together in some manner at seams in the
shoulder
area. The sleeves are commonly made from a flat piece of fabric that is folded
upon itself and joined together at a seam that runs the length of the sleeve
from
the shoulder to the wrist, prior to attachment to the main body portion. A
single tie
cord or a pair of tie cords is also usually attached to the main body portion
of the
gown. A single tie cord is used to encircle the wearer at the waist and tie to
itself
in order to keep the gown in position during use. Two tie cords are also used
to
encircle the wearer at the waist and tie to each other. The seams and the tie
cord
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attachment point are areas where many gowns have been known to fail the AAMI
test procedure.
A number of surgical gowns are currently marketed which are assembled
through the use of ultrasonic seam sealing. Ultrasonic seam sealing bonds the
layers of material together sufficiently for strength but the bonds do not
pass
ASTM-1671-b; the bacteriophage penetration resistance test, a test that is now
required to meet the new AAMI level 4 protection standards. This is
particularly
true for the sleeve seams and tie cord attachment point.
It is clear that there exists a need for a gown having tie cord attachments
bonded in a manner that is more impervious than current methods and that meets
AAMI level 4.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates an exemplary gown 100 to be worn during a medical
procedure as seen from the front.
Figure 2 illustrates an exemplary gown 100 to be worn during a medical
procedure as seen from the back.
Figure 3 represents a exemplary tie cord for a surgical gown.
SUMMARY OF THE INVENTION
In response to the foregoing difficulties encountered by those of skill in the
art,
we have successfully used thermal impulse heat welding, aka "bar sealing", to
bond
thermally sensitive laminate barrier materials made of thermoplastic polymers
such
that they will pass AAMI level 4 testing (ASTM 1670 and 1671-b). In bar
sealing,
overlapping layers of thermally sensitive barrier materials composed of
thermoplastic polymers are melted and fused together to create a substantially
solid bond at the surface of the materials. No substantially un-melted areas
remain within the fused seam area on the surface.
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DETAILED DESCRIPTION OF THE INVENTION
The present invention involves the use of bar sealing technology to meet
AAMI level 4 barrier properties in surgical gowns and similar articles formed
from
thermally sensitive laminate barrier materials that are composed of
thermoplastic
polymers. In bar sealing, overlapping layers of these thermally sensitive
laminate
barrier materials are melted and fused together to create a substantially
solid
bond at the surface of the materials while avoiding damage to regions below
the
surface of the laminate. No substantially un-melted areas remain within the
fused
bond area on the surface where heat was applied.
Figure 1 illustrates a typical gown 100 to be worn during a medical procedure
as seen from the front. The gown 100 includes a collar 110, the cuffs 120, the
primary tie cord 130 and a primary tie cord attachment area 140. The shoulder
seams 150 linking the sleeves 160 to the main body 170 are also visible.
Figure 2
illustrates a typical gown 100 to be worn during a medical procedure as seen
from
the back. In Figure 2 the shoulder seams 150 linking the sleeves 160 the main
body 170 are visible as are the sleeve seams 180 running from the shoulder
seams 150 to the cuffs 120 which are used to produce the sleeves160. Figure 2
also shows a secondary tie cord 180 and secondary tie attachment area 190 (not
in the AAMI critical zone). Figure 3 represents the tie cord 130 and shows the
end
to be bonded to the gown 100 as having, in this case, a "Y" shaped end 200 for
attachment to the gown 100. Note that a simple flat shaped end may also be
used
for attachment to the gown, a "Y" shape is not required.
Many surgical gowns are made from thermally sensitive laminate barrier
materials composed of thermoplastic polymers. While such barrier materials may
be
in the form of thermoplastic polymer spunbond fabrics, thermoplastic polymer
meltblown fabrics, and various combinations of such spunbond and meltblown
fabrics, a particularly desirable form of these barrier materials incorporate
one or
more thin, breathable films that provide desirable levels of resistance to
penetration
by liquids and pathogens while also providing satisfactory levels of
breathability
and/or moisture vapor transmission.
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These thin and breathable films are commonly made from thermoplastic
polyolefins like polyethylene and polypropylene and copolymers thereof because
of
their relatively low cost and ability to be processed. Polyethylene is
generally used
in the film production and the film is commonly "filled" with calcium
carbonate,
various kinds of clay, silica, alumina, barium carbonate, soldium carbonate,
magnesium carbonate, talc, barium sulfate, magnesium sulfate, aluminum
sulfate,
titanium dioxide, zeolites, cellulose-type powders, kaolin, mica, carbon,
calcium
oxide, magnesium oxide, aluminum hydroxide, pulp powder, wood powder,
cellulose
derivatives, chitin and chitin derivatives, to increase breathability. Fillers
produce
microscopic pores in the film upon stretching to increase porosity.
Unfortunately,
these thin and breathable films are considered to be thermally sensitive
because
they have a tendency to become compromised by heat and/or or pressure. When
these films are incorporated into laminate barrier materials by sandwiching
them
together with various combinations of other materials such as, for example,
spunbond fabrics, meltblown fabrics and combinations thereof, the resulting
laminate
barrier materials are generally considered to be thermally sensitive as well.
This
characterization is particularly important for post-laminate formation
processing
steps. That is, manufacturing operations that convert the thermally sensitive
barrier
fabrics after such films are formed into the laminate barrier fabrics. For
example,
when thermally sensitive barrier materials are converted into gowns or other
articles
utilizing thermal point bonding and/or ultrasonic bonding techniques or when
components such as, for example, tie cords or other features are attached to
the
articles, the breathable films of barrier laminate are frequently compromised
such
that they so longer provide desired levels of barrier to liquid penetration
and
pathogens.
The thin and breathable film laminates described above may be thermally
bonded using bar sealing, thus producing a thermal bond for a film layer-
containing
thermoplastic fabric where the bond joins a thermoplastic material to the
fabric to
form a fused bonded area, without bonding to the film layer. This bond has no
un-
melted areas remaining within the fused bond area on the surface.
"Spunbond" refers to fabric made from small diameter fibers which are formed
by extruding molten thermoplastic material as filaments from a plurality of
fine,
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usually circular capillaries of a spinneret with the diameter of the extruded
filaments
then being rapidly reduced as by, for example, in US Patent 4,340,563 to Appel
et
al., and US Patent 3,692,618 to Dorschner et al., US Patent 3,802,817 to
Matsuki et
al., US Patents 3,338,992 and 3,341,394 to Kinney, US Patent 3,502,763 to
Hartman, and US Patent 3,542,615 to Dobo et al. Spunbond fibers are generally
not
tacky when they are 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.
"Meltblown" fabric is 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
US Patent 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.
Laminates of spunbond and meltblown fabrics, e.g.,
spunbond/meltblown/spunbond (SMS) laminates and others are disclosed in U.S.
Patent 4,041,203 to Brock et al., U.S. Patent 5,169,706 to Collier, et al, US
Patent
5,145,727 to Potts et al., US Patent 5,178,931 to Perkins et al. and U.S.
Patent
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 to 12 osy (6 to 400 gsm), or more
particularly
from about 0.75 to about 3 osy. Multilayer laminates may also have various
numbers of meltblown layers or multiple spunbond layers in many different
configurations and may include other materials like films (F) or coform
materials, e.g.
SMMS, SM, SFS, etc.
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An exemplary method of forming a film includes a co-extrusion film apparatus
that forms the film with multiple layers consisting of skin and core layers.
Typically
the apparatus will include two or more polymer extruders. In one method of
fabrication, the film is extruded into a pair of nip or chill rollers. In
another method
the film is extruded onto a chilled roll which can have a smooth or matte
finish.
Typically, the film as initially formed will have an overall thickness of
approximately
25 to 60 micrometers with, in the case of multilayer films, the total skin or
bonding
layer having an initial thickness that may be about 3% to 30% of the total
thickness. Other film making processes known to those skilled in the art may
be
used as well, including cast embossing, chill and flat casting and blown film
processes.
From the coextrusion film apparatus the film is directed to a film stretching
unit such as a machine direction orienter (MDO), which is a commercially
available
device from vendors such as the Marshall and Williams Company of Providence,
R.I. Such an apparatus has a plurality of paired stretch rolls that move at
predetermined speeds that may rotate faster, slower or at the same speed
relative
to each other. Typically the stretch rolls move at a progressively faster
speeds to
progressively stretch and thin the film in the machine direction of the film,
which is
the direction of travel of the film through the process. The stretch rolls are
generally heated for processing advantages.
The temperatures to which the film is heated while stretching will depend on
the composition of the film as well as the breathability and other desired end
properties of the laminate. In most cases the film will be heated to a
temperature
no higher than 5 degrees C. below the melting point of the core or "B" layer
in the
film. The purpose for heating the film is to allow it to be stretched quickly
without
causing film defects. The amount of stretching will depend on the polymeric
composition, but, in general, the film may be stretched to about 300% or more
of
its original length (that is, a one cm length, for example, will be stretched
to 3 cm)
but less than the amount that tends to result in film defects. For most
applications,
for example, the stretch will be to at least 200% of the original film length
and,
frequently, in the range of about 250% to 500%.
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The multilayer stretch-thinned film may be attached to one or more support
layers to form a multilayer film/nonwoven laminate as described above. For
example, a conventional fibrous nonwoven web forming apparatus, such as a pair
of spunbond machines, may be used to form the support layer. The long,
essentially continuous fibers are deposited onto a forming wire as an unbonded
web and the unbonded web is then sent through a pair of bonding rolls to bond
the
fibers together and increase the tear strength of the resultant web support
layer.
One or both of the rolls are often heated to aid in bonding. Typically, one of
the
rolls is also patterned so as to impart a discrete bond pattern with a
prescribed
bond surface area to the web. The other roll is usually a smooth anvil roll
but this
roll also may be patterned if so desired.
Once the multilayer film has been sufficiently thinned and oriented and the
support layer has been formed, the two layers are brought together and
laminated
to one another using a pair laminating rolls or other means. As with the
bonding
rolls, the laminating rolls may be heated. Also, at least one of the rolls may
be
patterned to create a discrete bond pattern with a prescribed bond surface
area for
the resultant laminate. Generally, the maximum bond point surface area for a
given
area of surface on one side of the laminate will not exceed about 50 percent
of the
total surface area.
The process described above may be used to create a three layer laminate.
The only modification to the previously described process is to feed a supply
of a
second fibrous nonwoven web support layer into the laminating roll on a side
of the
multilayer film opposite that of the other fibrous nonwoven web support layer.
Alternatively, as with the other layers, the support layer may be formed
directly in-
line. In either event, the second support layer is fed into the laminating
rolls and is
laminated to the multilayer film in the same fashion as the other support
layer.
Exemplary processes and materials for forming thin films and laminates
may be found in commonly assigned US patent 5,188,885, 5,213,881, 5,271,883,
5,464,688, 5,695,868, 6,037,281, 6,309,736, 6,653,523 and 6,764,566,
incorporated herein in their entirety.
Multilayer film laminates may have various numbers of meltblown layers or
multiple spunbond layers in many different configurations and may include
other
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materials like coform materials. These include, for example,
spunbond/film/spunbond (SFS) laminates, spunbond/film/meltblown (SFM)
laminates, spunbond/meltblown/film (SMF) laminates and laminates having a
greater
number of layers like spunbond/film/spunbond/meltblown/spunbond (SFSMS) and
spunbond/meltblown/film/meltblown/spunbond SMFMS, coform/meltblown/film
(CMF) etc.
As used herein, the term "thermally sensitive materials" means fabrics and
webs which have a tendency to become compromised by heat and/or or pressure.
These materials have a relatively narrow range of temperature (the bonding
window)
at which they can be bonded and can be damaged to a great degree when
conditions fall outside of these ranges.
A "substantially solid bond" is one in which there are no substantially un-
melted areas within the bond footprint. This means that the thermoplastic
fibers on
the surface have been melted to a degree sufficient to produce a film. The
surface
film thus produced is the material which results in a bonding together of the
two
layers that are desired to be bonded.
Previous tie cord sealing methods tended to damage the layers of the gown
and to impair the liquid resistance of the bond to a point that the gown
failed the
AAMI level 4 test at the bond, or to be prohibitively expensive. These methods
included ultrasonic or thermal point bonding and adhesive bonding. The
inventors
believe, though do not wish to bound by that belief, that the former methods
tend to
bond materials through their entire thickness, thus disrupting the structure
to a
relatively high degree. Since many surgical gowns include a film layer in
order to
increase the penetration resistance of the gown and because film layers tend
to be
relatively weak, the robust bonding used previously tended to damage this
layer and
increase liquid penetration. In the case of adhesive bonding the manufacturing
challenges and expense are relatively great since adhesives tend to be
expensive
and time consuming to apply and can have detrimental effects on manufacturing
facility cleanliness. The inventors believe, though do not wish to bound by
that
belief, that bar sealing can bond a thermoplastic material to a second
thermoplastic
material that has a film layer within it, without damaging the barrier
properties of the
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film layer. Bar sealing is also substantially less expensive and less
challenging in a
manufacturing environment than is adhesive bonding.
Bar sealing uses heat, pressure and dwell time to thermally bond thermoplastic
materials together. According to the present invention, these variables are
adjusted
so that the thermal bonding takes place substantially at or adjacent the
surface of
the thermally sensitive barrier laminate materials while avoiding degradation
of the
thermally sensitive film component in an interior region of the barrier
laminate.
Bar sealing devices generally have a press with a set of jaws that open
(vertically), into which the materials to be bonded are placed. The jaws are
heated
by, for example, electric resistance heating and the temperature of each may
be
controlled separately. The pressure at which the jaws come together may also
be
adjusted for optimal bonding. Lastly, the time for which the jaws are together
(the
"dwell" or "hover" time) may also be adjusted. A dwell time of zero indicates
that the
jaws were brought together for an instant and immediately moved apart, i.e.,
they
were not held together.
Different applications may require different jaw sizes, but the size of jaw is
generally about a 1.75 cm (a half inch) wide , producing a bond width of about
0.635
cm ('/4 inch), by about 3.8 cm long (1.5 inches) to about 6.35 cm (2.5 inches)
long.
The jaw size may be as small as a half centimeter by a centimeter, depending
on the
materials to be joined.
An exemplary bar sealing device is available from Therm-O-Seal
Corporation of Mansfield, Texas. One such device is a Vertrod Style Steel
frame
sealer that has jaws about 1.75 cm wide and 2.54 cm in length and uses
electrical
resistance heating and water cooling. Another is a Vertrod style hand-held
heat
sealer that can produce a bond of 2, 4, 8 or 12 inches (5.1, 10.16, 20.3 and
30.5
cm) in length and 1/8, 3/16, '/4 and 3/8 inch (0.32, 0.48, 0.64 and 0.95 cm)
in width.
Yet another example of a bar sealing device is a Vertrod style table-top
vacuum
heat sealer producing seals 9, 14, 20, 24 and 30 inches (22.9, 35.6, 50.8, 61
and
76.2 cm) in length and 1/8, 3/16, '/4 and 3/8 inch in width.
As noted above, the process conditions will vary depending on the materials of
construction. For example, the current thermoplastic polymeric materials
commonly
used in disposable gowns and for components such as, for example, tie cords
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are presently attached to such disposable gowns, are typically nonwoven
fabrics
formed from polypropylene and/or polyethylene and have a basis weight
typically
ranging from about 0.5 (17 gsm) to about 1.5 osy (51 gsm).
Desirably, the tie cord material may be a folded 1.0 osy (34 gsm) SMS
material made as described above. Fabric for the fabrication of gowns may be,
for
example, made of random copolymer spunbond, a three layer
(Catalloy /polyethylene/Catalloy ) or "ABA" calcium carbonate filled film, and
a
spunbond/meltblown/spunbond (SMS) layer. This "SFSMS" may bonded together
to form the gown with the SMS against the skin. The spunbond layer and film
may
have a basis weight of between 0.2 and 1.0 osy (7 and 34 gsm) or more
particularly about 0.6 osy (20.3 gsm). The SMS layer may have a basis weight
of
between 0.5 and 1.5 osy (17 and 51 gsm) or more particularly about 0.75 osy
(25.4
gsm).
When these materials are used, the temperature of the bar sealer should be
between 240 and 320 F (116 and 160 C), the pressure should be between 40 and
80 psi (276 and 552 kPa) and the dwell time should be between 0 and 5 seconds.
More particularly, the temperature should be between 260 and 290 F (127 and
143
C), the pressure should be between 50 and 60 psi (345 and 414 kPa) and the
dwell
time should be between 1 and 3 seconds.
TEST METHODS
ASTM tests 1670 and 1671-b, procedure A: These tests are identical except that
1670 uses synthetic blood and 1671 uses Phi-X174 bacteriophage.
The test uses a penetration test cell available from Wilson Road Machine
Shop, Rising Sun, MD. The cell has a capacity of about 60 ml. In the test
cell, the
specimen acts as a partition separating the challenge fluid from the viewing
side of
the penetration cell. An annular flange cover with an open area to allow
visual
observations of the specimen, and a transparent cover are included. The cell
body
has top port for filling and a drain valve for draining the penetration test
cell. The
3 0 penetration cell is further specified in Test Method F903.
The fabric specimen is placed in the penetration cell with the layer that is
normally outermost facing the back (solid flange) part of the cell where the
challenge
11

CA 02661816 2009-02-25
WO 2008/026090 PCT/IB2007/052602
fluid is placed. The cell is filled through the top port with the challenge
fluid and
observed for 5 minutes. Air is then supplied to the top port and the sample
held at
13.8 kPa (2 psig) for 1 minute and the pressure released. If liquid
penetration is not
yet seen, the sample is allowed to stand for 54 minutes and observed. If
bacteriophage is the test fluid, the sample is subsequently assayed using a
0.5 ml
sample size onto agar for 6 to 18 hours at 35 to 37 C to test for passage of
fluid that
is not observable to the unaided eye.
EXAMPLES
Kimberly-Clark MicroCool surgical gowns are made of random copolymer
spunbond, a three layer (Catalloy /polyethylene/Catalloy ) calcium carbonate
filled film, and a spunbond/meltblown/spunbond (SMS) layer. This "SFSMS" is
bonded together to form the gown with the SMS against the skin. The random
copolymer of which the outermost layer of spunbond material is made is a 2.5
weight percent ethylene-propylene copolymer known as R532-35R, from the Dow
Chemical Company of Midland, MI. No treatments are applied to the fabric. The
spunbond layer and film each had a basis weight of 0.6 osy (20.3 gsm). The SMS
layer had a basis weight of 0.75 osy (25.4 gsm).
The tie cord to be bonded to the gown was a folded 1.0 osy (34 gsm) SMS
material. The material was folded either once for a double layer of fabric, or
twice
for a triple layer of fabric. The outer layer (spunbond) was made from a 2.5
weight
percent ethylene-propylene copolymer known as R532-35R, from the Dow
Chemical Company and the outer layer is treated with an antistat and a
fluorochemical to reduce surface tension. Prior to bonding to the gown, a
additional piece of tie cord material was bonded to the tie cord near an end
to
produce a "Y" shaped end for bonding to the gown on both upper end of the Y.
The Y was flattened out onto the gown for bonding at two points on the
branches
of the Y but near the stem of the Y.
A bar sealing device from Therm-O-Seal of Mansfield, Texas was used. It
was a Vertrod model number 2PF-ST-12004-55HT-WC-CRF-TC-KY-SP. This
device had jaws about 1.75 cm wide and 2.54 cm in length and used electrical
12

CA 02661816 2009-02-25
WO 2008/026090 PCT/IB2007/052602
resistance heating and water cooling. Only the jaw in contact with the tie
cord was
heated.
Example 1:
A double folded SMS tie cord was bonded to a MicroCool surgical gown at a
temperature of 275 to 282 F (135 to 139 C) at a zero dwell time and 56 psi
pressure (386 kPa). The bonded area was tested according to ASTM 1670. Nine
out of 11 samples passed and two failed.
Example 2:
A double folded SMS tie cord was bonded to a MicroCool surgical gown at
a temperature of 280 to 286 F (138 to 141 C) at a zero dwell time and 56 psi
pressure (386 kPa). The bonded area was tested according to ASTM 1670. All 11
samples passed
Example 3:
A double folded SMS tie cord was bonded to a MicroCool surgical gown at a
temperature of 290 to 296 F (143 to 147 C) at a zero dwell time and 56 psi
pressure (386 kPa). The bonded area was tested according to ASTM 1670. Nine
out of 11 samples passed and two failed.
Example 4:
The samples from Example 2 were tested according to ASTM 1671-b using
bacteriophage. Eleven of 11 samples passed.
As will be appreciated by those skilled in the art, changes and variations to
the invention are considered to be within the ability of those skilled in the
art.
Examples of such changes are contained in the patents identified above, each
of
which is incorporated herein by reference in its entirety to the extent it is
consistent
with this specification. Such changes and variations are intended by the
inventors
to be within the scope of the invention. It is also to be understood that the
scope of
the present invention is not to be interpreted as limited to the specific
embodiments
disclosed herein, but only in accordance with the appended claims when read in
light
of the foregoing disclosure.
13

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

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Event History

Description Date
Application Not Reinstated by Deadline 2011-07-04
Time Limit for Reversal Expired 2011-07-04
Deemed Abandoned - Failure to Respond to Maintenance Fee Notice 2010-07-05
Inactive: Cover page published 2009-06-29
Letter Sent 2009-06-03
Inactive: Notice - National entry - No RFE 2009-06-03
Inactive: Office letter 2009-06-03
Inactive: First IPC assigned 2009-05-06
Application Received - PCT 2009-05-05
National Entry Requirements Determined Compliant 2009-02-25
Application Published (Open to Public Inspection) 2008-03-06

Abandonment History

Abandonment Date Reason Reinstatement Date
2010-07-05

Maintenance Fee

The last payment was received on 2009-06-18

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  • the reinstatement fee;
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Fee History

Fee Type Anniversary Year Due Date Paid Date
Registration of a document 2009-02-25
Basic national fee - standard 2009-02-25
MF (application, 2nd anniv.) - standard 02 2009-07-03 2009-06-18
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
KIMBERLY-CLARK WORLDWIDE, INC.
Past Owners on Record
JOHN ANTHONY ROTELLA
MARY KATHERINE LAWSON
MICHAEL P. MATHIS
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
Documents

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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Description 2009-02-25 13 664
Claims 2009-02-25 2 59
Abstract 2009-02-25 2 64
Drawings 2009-02-25 3 19
Representative drawing 2009-06-04 1 5
Cover Page 2009-06-29 1 36
Reminder of maintenance fee due 2009-06-03 1 111
Notice of National Entry 2009-06-03 1 193
Courtesy - Certificate of registration (related document(s)) 2009-06-03 1 102
Courtesy - Abandonment Letter (Maintenance Fee) 2010-08-30 1 174
PCT 2009-02-25 5 163
Correspondence 2009-06-03 1 16