U.S. patent application number 11/646631 was filed with the patent office on 2008-07-03 for surgical gown tie attachment.
Invention is credited to Greg Hafer, Jerry Jascomb, Brian Lin.
Application Number | 20080155728 11/646631 |
Document ID | / |
Family ID | 39185841 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080155728 |
Kind Code |
A1 |
Hafer; Greg ; et
al. |
July 3, 2008 |
Surgical gown tie attachment
Abstract
There is disclosed the use of bonding and the placement of a
reinforcement piece to meet AAMI levels 3 and 4 barrier properties
in surgical gowns and similar articles formed from thermally
sensitive laminate barrier materials that are composed of
thermoplastic polymers. The reinforcement piece is placed on the
side opposite of the tie and the bonding uses a point-unbonded
pattern.
Inventors: |
Hafer; Greg; (Roswell,
GA) ; Lin; Brian; (Atlanta, GA) ; Jascomb;
Jerry; (Alpharetta, GA) |
Correspondence
Address: |
KIMBERLY-CLARK WORLDWIDE, INC.;Catherine E. Wolf
401 NORTH LAKE STREET
NEENAH
WI
54956
US
|
Family ID: |
39185841 |
Appl. No.: |
11/646631 |
Filed: |
December 28, 2006 |
Current U.S.
Class: |
2/69 |
Current CPC
Class: |
A41D 13/1209 20130101;
A41D 2300/52 20130101; A41D 2300/33 20130101; A41D 27/245
20130101 |
Class at
Publication: |
2/69 |
International
Class: |
A41D 13/12 20060101
A41D013/12 |
Claims
1. A surgical gown having an AAMI critical zone comprising a tie
cord bonded to said gown at a bond in said critical zone wherein
said bond passes AATCC test Method 127-1998.
2. The surgical gown of claim 1 further comprising a reinforcement
piece on a side opposite said tie cord.
3. The surgical gown of claim 3 wherein said reinforcement piece
has an area of at most 10 square inches.
4. The surgical gown of claim 1 wherein said bond is produced with
a PUB pattern.
5. The surgical gown of claim 4 wherein said bond has an area of
between about and 30 percent.
6. The surgical gown of claim 5 wherein said bond has an area of
about 25 percent.
7. A surgical gown having a tie cord, a reinforcement piece on the
side opposite said tie cord, and a tie cord bond area where said
tie cord is bonded to said gown and said reinforcement piece,
wherein said tie cord bond area passes ASTM test 1671-b.
8. The surgical gown of claim 7 wherein said gown comprises a
polyolefin microfiber layer.
9. The gown of claim 8 wherein said microfiber layer is a spunbond
layer which is made from polyethylene, polypropylene or an
ethylene-propylene copolymer.
10. The gown of claim 7 wherein said gown further comprises a
filled film.
11. The gown of claim 10 wherein said tie cord has an outer layer
that is treated with an antistat and a fluorochemical to reduce
surface tension.
12. The gown of claim 7 wherein said bond is made at a pressure
between 50 and 90 psi and for a weld time between 0.05 and 0.25
seconds.
13. The gown of claim 12 wherein said bond is made at a pressure
between 60 and 75 psi and for a weld time between 0.1 and 0.2
seconds
14. The gown of claim 12 wherein said bond is made at a pressure of
about 65 psi for a weld time of about 0.18 seconds.
15. A surgical gown having an AAMI critical zone of sleeves and
chest and comprising a tie cord bonded to said gown with a bond at
a tie cord bonding area in said critical zone, wherein said bond is
produced with a PUB pattern having an area of about 25 percent and
at a pressure of about 65 psi and a weld time of about 0.18
seconds, said gown is made from polypropylene SMS and has a
reinforcing section of polyethylene film in said AAMI critical
zone.
16. The gown of claim 15 wherein said tie cord bonding area passes
ASTM test 1671-b.
17. A method of bonding a tie cord to a surgical gown comprising
the steps of placing said tie cord on said gown and thermally
bonding them together at a tie cord bonding area with a PUB
pattern, wherein said tie cord bonding area passes AATCC test
Method 127-1998.
18. A method of bonding a tie cord to a surgical gown comprising
the steps of placing said tie cord on said gown, placing a
reinforcement piece on a side opposite said tie cord, and thermally
bonding them together at a tie cord bonding area where said tie
cord is bonded to said gown and said reinforcement piece with a PUB
pattern, wherein said tie cord bonding area passes ASTM test
1671-b.
Description
BACKGROUND OF THE INVENTION
[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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 weight of the gown. Generally, however, the
higher the breathability of the material, the lower the repellency
of the material.
[0005] 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 (chest),
including the tie cord attachment area, and the sleeves and sleeve
seam area up to about 2 inches (5 cm) above the elbow.
[0006] 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 attachment point are areas where many gowns have
been known to fail the AAMI test procedure.
[0007] 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, nor do they pass the
hydrohead test, AATCC test method 127-1998, for AAMI level 3
protection. This is particularly true for the sleeve seams and tie
cord attachment point.
[0008] 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 levels 3 and 4.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 illustrates an exemplary gown 100 to be worn during a
medical procedure as seen from the front.
[0010] FIG. 2 illustrates an exemplary gown 100 to be worn during a
medical procedure as seen from the back.
SUMMARY OF THE INVENTION
[0011] In response to the foregoing difficulties encountered by
those of skill in the art, we have successfully used a
point-unbonding bond pattern with and without a reinforcement patch
on medical gowns at the tie attachment point such that they will
pass AAMI level 3 (AATCC 127-1998 hydrohead) 4 testing (ASTM 1670
and 1671-b).
DETAILED DESCRIPTION OF THE INVENTION
[0012] The present invention involves the use of bonding and the
placement of a reinforcement piece to meet AAMI levels 3 and 4
barrier properties in surgical gowns and similar articles formed
from thermally sensitive laminate barrier materials that are
composed of thermoplastic polymers.
[0013] 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.
[0014] 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.
[0015] "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 al., 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 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.
[0016] "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 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.
[0017] Laminates of spunbond and meltblown fabrics, e.g.,
spunbond/meltblown/spunbond (SMS) laminates and others are
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 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
(abbreviated as "M") layers or multiple spunbond (abbreviated as
"S") layers in many different configurations and may include other
materials like films (abbreviated as "F") or coform materials (see
U.S. Pat. No. 4,100,324 for descriptions of exemplary "coform"
materials), e.g. SMMS, SM, SFS, etc.
[0018] 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.
[0019] 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.
[0020] 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 .degree. 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%.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] Exemplary processes and materials for forming thin films and
laminates may be found in commonly assigned U.S. Pat. Nos.
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.
[0025] FIG. 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. FIG. 2
illustrates a typical gown 100 to be worn during a medical
procedure as seen from the back. In FIG. 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 sleeves 160. FIG. 2 also shows a
secondary tie cord 180 and secondary tie attachment area 190 (not
in the AAMI critical zone).
[0026] 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 3 or 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.
[0027] 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 that 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).
[0028] 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.RTM./polyethylene/Catalloy.RTM.)
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).
[0029] The inventors have found that the attachment of a
reinforcement piece on the side opposite the tie cord attachment
side can provide sufficient assistance to the barrier properties
such that the attachment point passes the hydrohead test. The
reinforcement piece may be formed from various materials including
films, papers, meltblown fabrics, etc. provided, however that the
material from which the piece is made has a hydrohead above the
AAMI level 3 standard. The piece may also have an adhesive for ease
of application. The reinforcement piece may be, for example, a
wax-treated paper available under the tradename "Fastape" from the
Avery-Dennison Specialty Tape Division, 250 Chester St.,
Painesville, Ohio 44077. Fastape.RTM. paper also has an
adhesive.
[0030] The reinforcement piece must be sufficiently large to cover
the area of attachment of the tie cord. Generally a piece from
about 1.5 inches to 2.5 inches (38 to 64 mm) in width to about 2.5
to 4 inches (64 to 102 mm) in length should suffice, giving an area
of at most 10 square inches (645 square centimeters).
[0031] In addition to the reinforcement piece described above for
AAMI level 3 testing, the inventors have found that a change in the
bonding pattern is required in order to successfully reach AAMI
level 4 requirements. Previous thermal bonding patterns have used
"male" patterns. The inventors have found that "female" or
point-unbonded (PUB) patterns provide greatly improved bonding for
the purposes of the AAMI level 4. The method of attaching the
reinforcement piece is desirably by bonding it ultrasonically with
the new PUB bonding pattern.
[0032] Traditional "male" thermal point bonding generally involves
passing a fabric to be bonded between a heated calender roll and an
anvil roll. The calender roll is usually, though not always,
patterned in some way so that the entire fabric is not bonded
across its entire surface, and the anvil roll is usually flat. As a
result, various patterns for calender rolls have been developed for
functional as well as aesthetic reasons. One example of a pattern
has points and is the Hansen Pennings or "H&P" pattern with
about a 30% bond area with about 200 bonds/square inch as taught in
U.S. Pat. No. 3,855,046 to Hansen and Pennings. The H&P pattern
has square point or pin bonding areas wherein each pin has a side
dimension of 0.038 inches (0.965 mm), a spacing of 0.070 inches
(1.778 mm) between pins, and a depth of bonding of 0.023 inches
(0.584 mm). The resulting pattern has a bonded area of about 29.5%.
Another typical point bonding pattern is the expanded Hansen
Pennings or "EHP" bond pattern which produces a 15% bond area with
a square pin having a side dimension of 0.037 inches (0.94 mm), a
pin spacing of 0.097 inches (2.464 mm) and a depth of 0.039 inches
(0.991 mm). Another typical point bonding pattern designated "714"
has square pin bonding areas wherein each pin has a side dimension
of 0.023 inches, a spacing of 0.062 inches (1.575 mm) between pins,
and a depth of bonding of 0.033 inches (0.838 mm).
[0033] "Point unbonded" or "PUB" bonding means a fabric pattern
having continuous bonded areas defining a plurality of discrete
unbonded areas. The fibers or filaments within the discrete
unbonded areas are dimensionally stabilized by the continuous
bonded areas that encircle or surround each unbonded area and the
unbonded areas are specifically designed to afford spaces between
fibers or filaments within the unbonded areas. A suitable process
for forming the pattern-unbonded nonwoven material of this
invention includes providing a nonwoven fabric or web, providing
opposedly positioned first and second calender rolls and defining a
nip therebetween, with at least one of said rolls being heated and
having a bonding pattern on its outermost surface comprising a
continuous pattern of land areas defining a plurality of discrete
openings, apertures or holes, and passing the nonwoven fabric or
web within the nip formed by said rolls. Each of the openings in
said roll or rolls defined by the continuous land areas forms a
discrete unbonded area in at least one surface of the nonwoven
fabric or web in which the fibers or filaments of the web are
substantially or completely unbonded. Stated alternatively, the
continuous pattern of land areas in said roll or rolls forms a
continuous pattern of bonded areas that define a plurality of
discrete unbonded areas on at least one surface of said nonwoven
fabric or web. Examples of point unbonded patterns are illustrated
in U.S. Pat. No. 5,858,515 to Stokes et al.
[0034] The amount of bonding for use herein is between about 20 and
30 percent, preferably about 25 percent. An exemplary PUB pattern
for use in reaching the AAMI level 4 criteria is characterized by
multiple unbonded areas of 0.030'' (0.762 mm) open space and a
0.010'' (0.254 mm) seal line per every 0.040'' (1.016 mm),
producing a bond area of 25%.
[0035] The bonding "window" or conditions under which bonding takes
place, is between the point at which holes will form in the fabric
or where it will fail the AAMI levels 3 and 4 testing, and the
point at which ties will be easily pulled off of the gown after
bonding. The examples below were bonded using a Branson 900 series
ultrasonic welding machine by Branson Ultrasonics Corporation, of
Danbury Conn. The Branson 900 is controlled by setting the pressure
and weld or contact time between the bonding points and the
material. The pressure and contact time for use herein are between
50 and 90 psi and between 0.05 and 0.25 seconds, respectively, more
particularly between 60 and 75 psi and 0.1 and 0.2 seconds, still
more particularly about 65 psi and about 0.18 seconds.
[0036] The examples below show that the addition of a reinforcing
piece allows gowns to pass the AAMI level 3 test and that adding
PUB bonding allows the gown to pass AAMI level 4 testing.
Test Methods
[0037] AATCC test Method 127-1998: This test uses a Hydrostatic
Pressure Tester, apparatus available from Alfred Suter Co., PO Box
350, Ramsey N.J. 07445-0350. An alternative but similar tester, the
Textest Hydrostatic head Tester, is available from Schmid Corp.,
140-B Venture Blvd, Spartanburg, S.C. 29301.
[0038] The Suter apparatus is an inverted conical well equipped
with a coaxial ring clamp to fasten the cloth specimen under the
well bottom. The apparatus introduces water from above the specimen
over an area 114 mm in diameter at a rate of 10.0.+-.0.5 mm of
hydrostatic head per second. A mirror is affixed below the specimen
to enable the operator to ascertain penetration of the specimen by
drops of water. A valve is provided for venting the air in the
well.
[0039] A minimum of three fabric specimens should be taken
diagonally across the width of the fabric to be tested. Cut
specimens at least 200 by 200 mm to allow proper clamping. The
specimen should be conditioned at 21.degree. C. and 65 percent
relative humidity for at least 4 hours before testing. The specimen
is clamped in the apparatus with the surface to be tested facing
the water, which is at 21.degree. C. The apparatus is turned on and
water is introduced at the stated rate. Droplets appearing within 3
mm of the edge of the specimen should be disregarded and the
pressure at which droplets penetrate the fabric in three different
places is recorded. The pressure is reported as the height (in
millimeters) of water above the fabric. An average should be
calculated for each sample. The AAMI level 3 standard of 50 cm must
be reached in order to pass the test.
ASTM tests 1670 and 1671-b, procedure A: These tests are identical
except that 1670 uses synthetic blood and 1671 uses Phi-X174
bacteriophage.
[0040] 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 penetration cell
is further specified in Test Method F903.
[0041] 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 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.degree. C. to test for
passage of fluid that is not observable to the unaided eye.
Example Materials
Kimberly-Clark Ultra.RTM. Surgical Gowns
[0042] The Kimberly-Clark Ultra.RTM. Impervious gown is made from
1.5 osy (51 gsm) polypropylene SMS and has a reinforcing section in
the sleeves and chest (the AAMI "critical area"). The reinforcing
material is a 1 mil polyethylene film. The sleeve is bonded film to
film and turned inside out so the SMS is nearest the skin.
Kimberly-Clark MicroCool.RTM. Surgical Gowns:
[0043] Kimberly-Clark MicroCool.RTM. surgical gowns are made of
random copolymer spunbond, a three layer
(Catalloy.RTM./polyethylene/Catalloy.RTM.) calcium carbonate filled
film, and a polypropylene 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, Mich. 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).
Tie Cord:
[0044] 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.
EXAMPLE 1
Basic Ultra
[0045] A double folded SMS tie cord was bonded to an Ultra.RTM.
surgical gown at a weld time of 0.175 seconds and a pressure of 65
psi using a point bond pattern. The bonded area was tested
according to AATCC 127-1998. Twelve out of 12 samples failed.
EXAMPLE 2
Ultra with Fastape and PUB Bonding
[0046] A double folded SMS tie cord was bonded to an Ultral.RTM.
surgical gown at a weld time of 0.175 seconds and a pressure of 65
psi using a PUB bond pattern with 25 percent bond area as described
above. A 2.5 inch by 4 inch piece of Fastape.RTM. adhesive tape was
placed below the tie cord bond site prior to bonding. The bonded
area was tested according to AATCC 127-1998. Twelve out of 12
samples passed.
[0047] 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.
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