U.S. patent application number 11/636020 was filed with the patent office on 2008-06-12 for multiple layered absorbent fabric.
Invention is credited to David Matthews Laura.
Application Number | 20080139070 11/636020 |
Document ID | / |
Family ID | 39295921 |
Filed Date | 2008-06-12 |
United States Patent
Application |
20080139070 |
Kind Code |
A1 |
Laura; David Matthews |
June 12, 2008 |
Multiple layered absorbent fabric
Abstract
A multiple layered absorbent fabric comprising a liquid pervious
layer comprising at least one hydrophilic nonwoven web of melt spun
continuous multiple component fibers, a liquid impervious layer
comprising a film, and an absorbent layer comprising a spunlaced
web disposed between the liquid pervious layer and the liquid
impervious layer.
Inventors: |
Laura; David Matthews; (La
Vergne, TN) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY;LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1122B, 4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
39295921 |
Appl. No.: |
11/636020 |
Filed: |
December 8, 2006 |
Current U.S.
Class: |
442/400 |
Current CPC
Class: |
D04H 3/16 20130101; B32B
2262/0261 20130101; B32B 2262/062 20130101; D04H 3/14 20130101;
A61F 13/5148 20130101; B32B 2555/00 20130101; B32B 5/022 20130101;
B32B 2262/0276 20130101; B32B 2307/726 20130101; Y10T 442/68
20150401; B32B 27/32 20130101; B32B 5/26 20130101; B32B 27/12
20130101; B32B 2262/12 20130101; B32B 27/308 20130101; B32B
2262/0253 20130101; B32B 2262/14 20130101; B32B 27/306 20130101;
D04H 1/4374 20130101; D04H 1/56 20130101; B32B 2262/067
20130101 |
Class at
Publication: |
442/400 |
International
Class: |
D04H 1/56 20060101
D04H001/56 |
Claims
1-17. (canceled)
18. A multiple layered absorbent fabric comprising: (a) a liquid
pervious layer comprising at least one hydrophilic nonwoven web of
melt spun continuous multiple component fibers wherein the multiple
components are made from polymers with different melting points and
wherein the melt spun fibers have a length and a surface and the
polymers extend substantially along the complete length of the melt
spun fibers with the polymer having the lowest melting point
occupying at least a portion of the surface of the melt spun fiber;
(b) a liquid impervious layer comprising a film made from a polymer
having a melting point below the melting point of the melt spun
fiber polymers; and (c) an absorbent layer comprising a spunlaced
web disposed between the liquid perilous layer and the liquid
impervious layer, and (d) a backing layer comprising a fibrous web
positioned adjacent the liquid impervious layer opposite from the
absorbent layer.
19. The absorbent fabric of claim 18, wherein the hydrophilic
nonwoven web is treated with a hydrophilic surfactant.
20. The absorbent fabric of claim 19, wherein the hydrophilic
surfactant is a fatty acid ester.
21. The absorbent fabric of claim 18, wherein the hydrophilic
nonwoven web has at least one component made from a polymer with a
hydrophilic additive.
22. The absorbent fabric of claim 18, wherein the hydrophilic
nonwoven web comprise at least one spunbond web.
23. The absorbent fabric of claim 22, wherein the hydrophilic
nonwoven web comprise at least one spunbond web and at least one
meltblown web wherein the at least one meltblown web is disposed
between the at least one spunbond web and the absorbent layer.
24. The absorbent fabric of claim 23, wherein the hydrophilic
nonwoven web comprise two spunbond webs and at least one meltblown
web wherein the at least one meltblown web is disposed between the
two spunbond webs.
25. The absorbent fabric of claim 18, wherein the melt spun
continuous multiple component fibers comprise bicomponent
fibers.
26. The absorbent fabric of claim 25, wherein the polymers of the
multiple components are selected from the group consisting of
polyolefins, polyesters, polyamides and copolymers thereof.
27. The absorbent fabric of claim 25, wherein a combination of
polymers of the bicomponent fibers comprises a polyolefin and a
polyester.
25. The absorbent fabric of claim 18, wherein the polymer of the
film is selected from the group consisting of polyolefin, ethylene
vinyl acetate copolymer, and ethylene maleic anhydride.
29. The absorbent fabric of claim 18, wherein the spunlaced web
comprises at least some naturally absorbent fibers.
30. The absorbent fabric of claim 29, wherein the naturally
absorbent fibers are selected from the group consisting of wood
pulp, cellulose, and cotton.
31. The absorbent fabric of claim 29, wherein the spunlaced web
further comprises at least some synthetic fibers.
32. The absorbent fabric of claim 31, wherein the synthetic fibers
are polyester fibers.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a multiple layered absorbent
fabric that can be used in the medical and hygiene markets,
especially for medical drapes.
[0003] 2. Background of the Invention
[0004] Medical drapes are typically made from absorbent fabrics
that are engineered to absorb bodily fluids on one side containing
an absorbent layer and resist fluid migration out the other side by
use of a liquid impervious layer. The absorbent layer often
contains naturally absorbent fibrous materials such as wood pulp,
cellulose, cotton, and absorbent particles. The liquid impervious
layer is often made from a film laminated to the absorbent
layer.
[0005] However, since the absorbent layer can be made with short
discontinuous fibers or particles, the absorbent fabric can be
susceptible to unacceptable linting. U.S. Patent Publication No.
2005/0054255 describes the use of a liquid pervious layer
comprising a nonwoven fabric laminate adjacent the absorbent layer
that allows fluids to pass through the liquid pervious layer while
preventing the loss of absorbent material.
[0006] It would be a further improvement to a three layer absorbent
fabric to make the liquid pervious layer autogenously bondable and
have the ability to bond the liquid impervious layer of the three
layer absorbent fabric to a backing layer without damaging the
three layer absorbent fabric.
SUMMARY OF THE INVENTION
[0007] This invention is directed to a multiple layered absorbent
fabric comprising a liquid pervious layer comprising at least one
hydrophilic nonwoven web of melt spun continuous multiple component
fibers wherein the multiple components are made from polymers with
different melting points and wherein the melt spun fibers have a
length and a surface and the polymers extend substantially along
the complete length of the melt spun fibers with the polymer having
the lowest melting point occupying at least a portion of the
surface of the melt spun fiber, a liquid impervious layer
comprising a film made from a polymer having a melting point below
the melting point of the melt spun fiber polymers, and an absorbent
layer comprising a spunlaced web disposed between the liquid
pervious layer and the liquid impervious layer.
[0008] This invention is further directed to a multiple layered
absorbent fabric described above wherein the absorbent fabric
further comprises a backing layer comprising a fibrous web
positioned adjacent the liquid impervious layer opposite from the
absorbent layer.
DETAILED DESCRIPTION OF THE INVENTION
[0009] Reference now will be made to the embodiments of the
invention, one example of which is set forth below. The example is
provided by way of explanation of the invention, not as a
limitation of the invention. In fact, it will be apparent to those
skilled in the art that various modifications and variations can be
made in this invention without departing from the scope or spirit
of the invention. For instance, features illustrated or described
as part of one embodiment can be used on another embodiment to
yield a still further embodiment. Thus, it is intended that the
present invention cover such modifications and variations as come
within the scope of the appended claims and their equivalents.
Other objects, features, and aspects of the present invention are
disclosed in or are obvious from the following detailed
description. It is to be understood by one of ordinary skill in the
art that the present discussion is a description of exemplary
embodiments only, and is not intended as limiting the broader
aspects of the present invention, which broader aspects are
embodied in the exemplary constructions.
[0010] In general, the present invention is directed to an improved
multiple layered absorbent fabric for use in the medical and
hygiene markets especially medical drapes. The improved multiple
layered absorbent fabric comprises a liquid pervious layer, a
liquid impervious layer, and an absorbent layer disposed between
the liquid pervious layer and the liquid impervious layer. The
improvement comprises a liquid pervious layer of at least one
hydrophilic nonwoven web of melt spun continuous multiple component
fibers wherein the multiple components are made from polymers with
different melting points and wherein the melt spun fibers have a
length and a surface and the polymers extend substantially along
the complete length of the melt spun fibers with the polymer having
the lowest melting point occupying at least a portion of the
surface of the melt spun fiber. By locating the lowest melting
point polymer on at least a portion of the surface of the melt spun
fiber, the hydrophilic nonwoven web can be heated to autogenously
bond the fibers together to form a strong web.
[0011] In another embodiment of the present invention, by selecting
a liquid impervious layer comprising a film made from a polymer
having a melting point below the melting point of the melt spun
fiber polymers, a backing layer can be affixed to the liquid
impervious layer by heating the four layer to cause the liquid
impervious layer to bond to the backing layer without melting and
damaging the fibers in the liquid pervious layer.
[0012] The liquid pervious layer comprises at least one hydrophilic
nonwoven web. The hydrophilic nature of the web allows fluids to
migrate through the web. If the web is not inherently hydrophilic
or hydrophilic enough for the intended use of the absorbent fabric,
then the web can be treated with a hydrophilic surfactant. The
hydrophilic surfactant can be applied to the web by dipping the
fabric in an aqueous solution containing the hydrophilic surfactant
or other methods known in the art. An example of a hydrophilic
surfactant is a nonionic fatty acid ester. Another method for
making the web hydrophilic is spinning a hydrophilic additive into
at least one polymer of the fibers of the web. This can be achieved
by selecting a thermally compatible hydrophilic additive and
blending it into the polymer prior to fiber spinning.
[0013] The hydrophilic nonwoven web of melt spun continuous
multiple component fibers of the liquid pervious layer can comprise
at least one spunbond web, at least one meltblown web, or
combinations of thereof. Typically, spunbond webs are stronger than
meltblown webs and at least one spunbond web would be located on
the outermost location of the absorbent fabric. The presence of the
meltblown web, which can have smaller diameter size fibers than
spunbond fibers, typically forms a more efficient barrier for
absorbent materials and particles to pass through than a spunbond
web. Therefore, a hydrophilic nonwoven web comprising the
combination of at least one spunbond web and at least one meltblown
web wherein the at least one meltblown web is disposed between the
at least one spunbond web and the absorbent layer provides a strong
barrier for resisting absorbent material migration through the
liquid pervious layer. A typical combination of spunbond and
meltblown webs is a spunbond-meltblown-spunbond or SMS
construction. This produces a strong composite web with strong
particle barrier properties.
[0014] The multiple component fibers of the liquid impervious layer
are made from polymers with different melting points and wherein
the melt spun fibers have a length and a surface and the polymers
extend substantially along the complete length of the melt spun
fibers with the polymer having the lowest melting point occupying
at least a portion of the surface of the melt spun fiber. By
locating the lowest melting point polymer on at least a portion of
the surface of the melt spun fiber, the hydrophilic nonwoven web
can be heated to autogenously bond the fibers together to form a
strong web. The polymers of the multiple components are selected
from the group consisting of polyolefins, polyesters, polyamides,
and copolymers thereof. Multiple component fibers typically include
bicomponent fibers. A useful combination of polymers of the
bicomponent fibers comprises a polyolefin and a polyester. Methods
to produce these types of spunbond and meltblown webs are disclosed
for example in U.S. Pat. Nos. 6,831,025 and 6,776,858 herein
incorporated by reference.
[0015] The film of the liquid impervious layer is made from a
polymer having a melting point below the melting point of the melt
spun fiber polymers. Examples of polymers suitable for use in the
present invention include polyolefins, ethylene vinyl acetate
copolymers, and ethylene maleic anhydrides. The film layer is
attached to the absorbent layer using a pressure sensitive adhesive
or other method known in the art.
[0016] The absorbent layer comprises a spunlaced web disposed
between the liquid pervious layer and the liquid impervious layer.
The spunlaced web can include at least some naturally absorbent
fibers such as wood pulp, cellulose or cotton. The spunlaced web
can also include at least some synthetic fibers such as polyester
fibers. A preferred spunlaced web includes a blend of polyester
fibers and wood pulp. The preparation of a spunlaced web is well
known in the art.
[0017] The multiple layered absorbent fabric can include a fourth
layer or backing layer comprising a fibrous web positioned adjacent
the liquid impervious layer opposite from the absorbent layer. The
fibrous web is affixed to the film of the liquid impervious layer
by heating all four layers of the multiple layered absorbent fabric
to a temperature that causes the film to bond to the fibrous web
without melting or damaging the fibers in the hydrophilic nonwoven
web.
Test Methods
[0018] In the description above and in the examples that follow,
the following test methods were employed to determine various
reported characteristics and properties.
[0019] Lint Generation is a measure of the number of airborne
particles generated when a sheet is subjected to a twisting and
compression action. The test was conducted according to ISO
9073-10, which is hereby incorporated by reference and is reported
as a linting coefficient.
[0020] Hydrostatic Head is a measure of the resistance of the sheet
to penetration by liquid water under static pressure. The test was
conducted according to AATCC-127, which is hereby incorporated by
reference and is reported in centimeters.
[0021] Hydrostatic Head Loss is a measure of the reduction in
hydrostatic head that results from a specific treatment meant to
simulate how the resistance of a sheet to penetration by water may
be reduced by contact with another fabric. In this specific
treatment, an absorbent material is placed in the sample holder of
a Nu-Martindale Abrasion and Pilling Tester and 5 ml of an aqueous
solution containing 0.9% (w/w) sodium chloride is allowed to absorb
in to the fabric. A repellent material is then placed on top of the
absorbent material and held in place by the sample holder. The
repellent sheet is made from Suprel.RTM., which is a
spunbond-meltblown-spunbond (SMS) nonwoven made from
polyethylene/polyester bicomponent fibers and is available from E.
I. du Pont de Nemours and Company, Wilmington, Del. (DuPont).
[0022] The lid of the tester is then lowered on top of the samples
and applies 12 kPA of pressure through a metal surface on to the
back of the repellent fabric. The Nu-Martidale tester then makes
150 cycles in the "C" pattern. This action is meant to simulate the
repeated contact that may occur when an absorbent fabric comes in
to contact with a repellent fabric such as when a repellent
operating room garment comes in to contact with an absorbent
operating room drape. The hydrostatic head of the repellent fabric
that has been subjected to this treatment is measured immediately
after this treatment. The hydrostatic head of the untreated
repellent material is also measured, where the "untreated repellent
material" refers to the repellent material before it has been
subjected to any treatment. The hydrostatic head loss is the
difference between the hydrostatic head of the untreated repellent
material and the hydrostatic head of the repellent material after
this treatment and is reported in centimeters and as a percentage
of loss from the untreated material.
EXAMPLES
[0023] Hereinafter the present invention will be described in more
detail in the following examples.
Comparative Example A
[0024] A two-layer absorbent fabric was made by combining an
absorbent layer and a liquid impervious layer. The absorbent layer
was a spunlaced fabric containing woodpulp and poly(ethylene
terephthalate) polyester fibers in a ration of 55% (w/w) woodpulp
to 45% (w/w) polyester having a basis weight of 71.5 grams per
square meter available from DuPont as Sontara.RTM. style 9927. The
liquid impervious layer was a film layer made from low density
polyethylene and has a thickness of approximately 1 mil. The film
layer was attached to the absorbent layer using a pressure
sensitive adhesive (Sprayway.RTM. 82C Mist Adhesive).
[0025] In the hydrostatic head loss test, the untreated repellent
fabric had a hydrostatic head of 84.4 cm and this fabric caused a
hydrostatic head loss of 3.9 cm corresponding to a hydrostatic head
loss percentage of 3.9%.
Comparative Example B
[0026] A two-layer fabric was made according to the procedure of
Comparative Example A except that the absorbent layer was treated
with a hydrophilic surfactant and an antistatic agent. The
hydrophilic surfactant was a nonionic fatty acid ester available
from Uniqema as Cirrasol.RTM. G2109. The antistatic agent was a
phosphate ester available from Stepan as Zelec.RTM. TY. The
absorbent layer was dipped into an aqueous bath of 0.75% (w/w)
Cirrasol G2109 and 0.25% (w/w) Zelec TY. The sheet was then
squeezed to remove excess liquid and dried in an oven at
160.degree. C. for 2 minutes.
[0027] In the hydrostatic head loss test, the untreated repellent
fabric had a hydrostatic head of 84.4 cm and this fabric caused a
hydrostatic head loss of 80.0 cm corresponding to a hydrostatic
head loss percentage of 94.7%.
Example 1
[0028] A three-layer fabric was made in accordance with the
invention by combining a liquid pervious layer, a spunlaced
absorbent layer, and a liquid impervious layer. The liquid pervious
layer was made by thermally bonding three layers of meltspun fibers
where the first layer was a spunbond fabric made of bicomponent
sheath/core fibers made with 50 wt % polyethylene melting point
128.degree. C. sheath and 50 wt % poly(ethylene terephthalate)
melting point 258.degree. C. core. The second layer of the liquid
pervious layer was made of a meltblown fabric having 30 wt %
polyethylene melting point 128.degree. C. and 70 wt % poly(ethylene
terephthalate) melting point 258.degree. C. side-by-side
bicomponent fibers. The third layer of the liquid pervious layer
was identical to the first. This spunbond-meltblown-spunbond sheet
was treated by dipping in an aqueous solution of 20% (w/w)
isopropanol wherein isopropanol is used as a wetting agent for this
fabric, 0.75% (w/w) Cirrasol G2109 hydrophilic surfactant and 0.25%
(w/w) Zelec TY antistatic agent. The sheet was then squeezed to
remove excess liquid and dried in an oven at 105.degree. C. for 2
minutes. The absorbent layer was a spunlaced fabric having a basis
weight of 40 grams per square meter and having 65% (w/w) lyocell
fibers and 35% (w/w) poly(ethylene terephthalate) fibers. The
liquid impervious layer was a film made from a copolymer of
ethylene and vinyl acetate having 18% (w/w) vinyl acetate and a
melting point of 86.degree. C. The film layer was attached directly
to the absorbent layer by extrusion coating. The absorbent layer
was attached to the liquid pervious layer using 3 grams per square
meter of a hot-melt adhesive H2900 available from Bostik.
[0029] The linting generation test provided a linting coefficient
of 3.72 for particles greater than 0.5 microns whereas a fabric
similar to Comparative Example B generated a linting coefficient of
5.88 in this test. The presence of the liquid pervious layer in
Example 1 provided a reduction in linting as compared to a fabric
similar to Comparative Example B.
[0030] In the hydrostatic head loss test the untreated repellent
fabric had a hydrostatic head of 84.4 cm and this fabric caused a
hydrostatic head loss of 39.3 cm corresponding to a hydrostatic
head loss percentage of 46.5%. Based on the hydrostatic head loss
data, less hydrophilic surfactant is transferred from the absorbent
drape to the untreated repellent material for Example 1 as compared
to Comparative Example B. Although hydrophilic surfactant aids the
transfer of water through the liquid pervious layer, less
hydrophilic surfactant (and, hence, less contamination) is
transferred to the untreated repellent material as compared to
hydrophilic surfactant treated absorbent layer without a liquid
pervious layer in Comparative Example B.
* * * * *