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Patent 2473950 Summary

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(12) Patent Application: (11) CA 2473950
(54) English Title: NONWOVEN WEB INCLUDING A SUPERABSORBENT REGION AND ARTICLES INCLUDING THE SAME
(54) French Title: BANDE CONTINUE NON TISSEE INCLUANT UNE REGION SUPERABSORBANTE ET ARTICLES CONTENANT CETTE BANDE
Status: Dead
Bibliographic Data
(51) International Patent Classification (IPC):
  • A61F 13/15 (2006.01)
(72) Inventors :
  • MEHAWEJ, FOUAD D. (United States of America)
(73) Owners :
  • H.B. FULLER LICENSING & FINANCING, INC. (United States of America)
(71) Applicants :
  • H.B. FULLER LICENSING & FINANCING, INC. (United States of America)
(74) Agent: GOWLING LAFLEUR HENDERSON LLP
(74) Associate agent:
(45) Issued:
(86) PCT Filing Date: 2003-02-04
(87) Open to Public Inspection: 2003-08-14
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/US2003/003267
(87) International Publication Number: WO2003/065953
(85) National Entry: 2004-07-21

(30) Application Priority Data:
Application No. Country/Territory Date
10/066,935 United States of America 2002-02-04
10/274,335 United States of America 2002-10-18

Abstracts

English Abstract




An absorbent article that includes a nonwoven web that includes synthetic
polymer fibers, a first surface, a second surface opposite the first surface,
a first region including superabsorbent polymer, the first region extending
into the nonwoven web from the first surface toward the second surface, and a
second region essentially free of superabsorbent polymer, the second region
extending into said nonwoven web from the second surface toward the first
surface.


French Abstract

L'invention concerne un article absorbant qui comprend : une bande continue non tissée contenant des fibres polymères synthétiques ; une première surface ; une deuxième surface opposée à la première surface ; une première région contenant un polymère superabsorbant, cette première région s'étendant à l'intérieur de la bande non tissée, de la première surface vers la deuxième surface ; et une deuxième région essentiellement exempte de polymère superabsorbant, cette deuxième région s'étendant à l'intérieur de la bande continue non tissée, de la deuxième surface vers la première surface.

Claims

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



1. An absorbent article comprising:
a nonwoven web comprising
synthetic polymer fibers;
a first surface;
a second surface opposite said first surface;
a first region comprising superabsorbent polymer, said first
region extending into said nonwoven web from said first surface
toward said second surface, said superabsorbent polymer having been
formed in situ in said first region; and
a second region essentially free of superabsorbent polymer,
said second region extending into said nonwoven web from said
second surface toward said first surface.
2. The absorbent article of claim 1, wherein said second region extends
into the thickness of said nonwoven web a distance sufficient to prevent a
wearer of
the article from contacting said superabsorbent polymer of said first region
after said
superabsorbent polymer has been contacted with liquid.
3. The absorbent article of claim 1, wherein said first region is
impregnated with said superabsorbent polymer.
4. The absorbent article of claim 1, wherein said second region exhibits a
property comprising fluid acquisition, fluid dispersion or a combination
thereof.
5. The absorbent article of claim 1, wherein said synthetic polymer fibers
comprise polyester, polyolefin, polyamide, polyurethane, polyacrylonitrile, or
a
combination thereof.
6 The absorbent article of claims 1-5, wherein at least one of said first
region and said second region comprises a first plurality of fibers comprising
a first
polymer and a second plurality of fibers comprising a second polymer.
7. The absorbent article of any one of claims 1-5, wherein said second
region is soft to the touch.
18


8. The absorbent article of any one of claims 1-5 further comprising
cellulose fibers.
9. The absorbent article of any one of claims 1-5, wherein said first
region is substantially coextensive with said second region.
10. The absorbent article of any one of claims 1-5, wherein said absorbent
article comprises
a top sheet; and
a back sheet;
said nonwoven web being disposed between said top sheet and said
back sheet.
11. The absorbent article of claim 10, wherein said back sheet is liquid
impervious, moisture vapor permeable or a combination thereof.
12. A disposable diaper, feminine hygiene product, bandage, wound care
product, surgical pad, adult incontinence pad, breast pad, bib or mattress pad
comprising the absorbent article of any one of claims 1-5.
13. A personal hygiene article comprising an absorbent core comprising
the article of any one of claims 1-5.
14. A method of making an absorbent article, said method comprising:
impregnating a first region of a nonwoven web with an aqueous
composition comprising a superabsorbent polymer precursor and a
crosslinking agent, said first region extending from a first surface of said
web
into the depth of the web such that the second surface of said web opposite
said first surface of said web is free of superabsorbent polymer precursor;
and
drying said composition.
15. The method of claim 14, wherein said drying comprises exposing said
composition to microwave radiation.
19

Description

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




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NONWOVEN WEB 1NCLUD1NG A SUPERABSORBENT REGION AND
ARTICLES INCLUDING THE SAME
REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of United States Patent Application
Serial No. 10/066,935, filed February 4, 2002.
BACKGROUND
The invention relates a nonwoven web having a superabsorbent region.
Absorbent articles such as disposable diapers and feminine hygiene products
often include multiple layers including a top sheet, an acquisition layer, a
core of
compressed cellulose fibers, often referred to as "fluff' or "pulp," held
together with
chemical binder, or through physical entanglement and compression, and a back
sheet. These individual components are combined during manufacturing to
produce
the finished article.
The top sheet and acquisition layer are individual components, function to
disperse liquid, which enables the liquid to transfer to a greater area of the
core, and
assist in maintaining a dry feel to the wearer's skin. The top sheet and
acquisition
layer are discreet components of the absorbent article, often are composed of
materials that differ from the material of the absorbent core, and tend to
have little to
no absorbent capacity.
The absorbent core is designed to absorb and hold liquid. Many efforts have
been made to increase the absorbent capacity and rate of absorption of
cellulose fiber
cores. Superabsorbent polymers in particulate and powder form have been added
to
disposable diaper and feminine napkin cores to improve the absorbent capacity
and
rate of absorption of the articles. In the case of a diaper construction, for
example,
superabsorbent powder or particulate is sifted in with the absorbent core
material
during the diaper manufacturing process. Many problems are associated with
superabsorbent powders. Superabsorbent particles are very fine and tend to
become
airborne during processing. Superabsorbent particles also generally do not
adhere to
the substrate and tend to migrate and shift during manufacturing, shipping,
handling,
use or a combination thereof. The movement of the superabsorbent particles can
lead
to insufficient liquid storage capacity in some areas and excess liquid
storage capacity
in other areas of the article.



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Cellulose fiber cores have disadvantages in that they have weak integrity in
both, dry and wet, conditions. Additional compression and embossing processes
designed to improve the integrity of cellulose fiber cores often result in a
stiffer core
having a poor absorption rate. In addition, during the manufacture of
cellulose fiber
cores loose fibers become air-borne and may present a safety hazard.
Airlaid or pre-made absorbent cores provide a thinner core product and reduce
at least some of the problems related to the processing of loose cellulose
fibers, but
tend to lack integrity. Chemical binders are often used to improve the
integrity of
airlaid cores. However, chemical binders tend to negatively impact the
absorption
rate and absorption capacity of the core.
SUMMARY
In one aspect the invention features an absorbent article that includes a
nonwoven web that includes synthetic polymer fibers, a first surface, a second
surface
opposite the first surface, a first region that includes superabsorbent
polymer, the first
region extending into the nonwoven web from the first surface toward the
second
surface, and a second region essentially free of superabsorbent polymer, the
second
region extending into the nonwoven web from the second surface toward the
first
surface.
In one embodiment, the second regian extends into the thickness of the
nonwoven web a distance sufficient to prevent the wearer of the article from
contacting the superabsorbent polymer of the first region after the
superabsorbent
polymer has been contacted with liquid.
In some embodiments, the first region is impregnated with the superabsorbent
polymer.
In other embodiments, the second region exhibits a property that includes
fluid
acquisition, fluid dispersion or a combination thereof. In some embodiments,
the
second region is available for contact with the wearer of the absorbent
article.
In another embodiment, the first region is capable of storing fluid.
In some embodiments, the second region includes a first plurality of fibers of
a
first polymer and a second plurality of fibers of a second polymer.
In other embodiments, the second region is soft to the touch.
In another embodiment, the absorbent article includes a top sheet, and a back
sheet, the nonwoven web being disposed between the top sheet and the back
sheet. In
one embodiment, the back sheet is positioned away from a wearer's skin.



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In some embodiments, the back sheet is liquid impervious.
In other embodiments, the back sheet is moisture vapor permeable.
In another embodiment, the first region is substantially coextensive with the
second region.
, In one embodiment, the article is free of a fluid acquisition sheet or a
fluid
dispersion sheet.
In other embodiments, a disposable diaper, feminine hygiene product,
bandage, wound care product, surgical pad, adult incontinence pad, breast pad,
bib or
mattress pad that includes an absorbent article described herein.
In one embodiment, the absorbent article that includes an absorbent core that
includes a nonwoven web of synthetic polymer fibers, a first surface, a second
surface
opposite the first surface, a first region that includes superabsorbent
polymer, the
superabsorbent polymer having been formed in situ, the first region extending
into the
nonwoven web from the first surface toward the second surface, and a second
region
essentially free of superabsorbent polymer, the second region extending into
the
nonwoven web from the second surface toward the first surface.
In another aspect, the invention features an absorbent core dimensioned for
use in an absorbent article, the core includes a nonwoven web that includes
synthetic
polymer fibers, a liquid storage region that includes a superabsorbent polymer
formed
in situ in the region, the liquid storage region extending into the nonwoven
web from
a first surface of the nonwoven web toward a second surface of the nonwoven
web,
and a liquid acquisition region free of superabsorbent polymer, the liquid
acquisition
region extending into the nonwoven web from a first surface of the nonwoven
web
toward the liquid storage region.
In another aspect, the invention features an article that includes a nonwoven
web that includes a first surface, a second surface opposite the first
surface, a fluid
storage region includes superabsorbent polymer, the fluid storage region
extending
into the nonwoven web from the second surface of the web toward the first
surface of
the web the superabsorbent polymer having been formed in situ in the fluid
storage
region, and a fluid acquisition region essentially free of superabsorbent
polymer, the
fluid acquisition region extending into the nonwoven web from the first
surface
toward the second surface.
In other aspects, the invention features a method of making an absorbent
article, the method including impregnating a first region of a nonwoven web
with an



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aqueous composition that includes a superabsorbent polymer precursor and a
crosslinking agent, the first region extending from a first surface of the web
into the
depth of the web such that the second surface of the web opposite said first
surface of
said web is free of superabsorbent polymer precursor, and drying the
composition. In
one embodiment, the drying includes exposing the composition to microwave
radiation. In another embodiment, the drying includes exposing the composition
to
heat.
In one embodiment, the method of making an absorbent article includes
impregnating a high loft nonwoven web with an aqueous composition that
includes a
superabsorbent polymer precursor and a crosslinking agent, and drying the
composition, the drying including exposing the composition to microwave
radiation,
wherein the dried absorbent article includes from 10 % by weight to about 90 %
by
weight superabsorbent polymer.
The invention features a nonwoven web that can be constructed to provide a
fluid acquisition function, a fluid distribution function, and a fluid storage
function.
The nonwoven web enables the construction of an absorbent article (e.g.,
personal
hygiene article) in which a single component provides a fluid acquisition
function, a
fluid distribution function, and a fluid storage function.
Other features of the invention will be apparent from the following
description
of the preferred embodiments thereof, and from the claims.
GLOSSARY
In reference to the invention, these terms have the meanings set forth below:
"Superabsorbent polymer precursor" means a polymer that is capable of
functioning as a superabsorbent polymer upon crosslinking.
"Superabsorbent polymer" means a polymer that is capable of absorbing water
in an amount that is many times the polymer's weight.
DETAILED DESCRIPTION
The nonwoven web includes synthetic polymer fibers, a first region that
includes superabsorbent polymer and extends from a first surface of the web
into the
depth (i.e., thickness) of the web, and a second region that is free of
superabsorbent
polymer and extends from a second surface of the web into the depth of the
web, the
second surface being opposite the first surface of the web. The first and
second
regions are preferably continuous across the length and width of the web and
extend
into the depth of the web a distance less than 100 % of the depth of the web.
The first



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and second regions are also preferably contiguous or substantially contiguous
with
each other.
The superabsorbent polymer containing first region is herein referred to as
the
superabsorbent region. The superabsorbent region is preferably impregnated
with
superabsorbent polymer, i.e., superabsorbent polymer is present throughout the
three
dimensional matrix of the web in the superabsorbent region. The superabsorbent
polymer can reside on the fibers of the web in the region, in the interstices
of the web
in the region or a combination thereof.
The depth to which the superabsorbent region extends into the web is
referred to herein as the thickness of the superabsorbent region. Preferably
the
superabsorbent region extends into the web a depth sufficient to provide the
desired
absorbent capacity and absorption rate for the intended use of the absorbent
article.
The superabsorbent region of the web preferably includes from about 10 % by
weight
to about 70 % weight superabsorbent polymer, more preferably from about 10 %
by
weight to about 70 % by weight superabsorbent polymer, most preferably from
about
30 % by weight to about 60 % by weight superabsorbent polymer.
The superabsorbent region of the web exhibits good saline absorption under
load, high saline absorption capacity and high water absorption capacity.
Preferably
the superabsorbent region exhibits a saline absorption capacity under load of
at least
10 g 0.9 % saline solution/g superabsorbent region under a 0.3 pound per
square inch
(psi) load, more preferably at least 15 g 0.9 % saline solution/g
superabsorbent region,
most preferably at least 20 g 0.9 % saline solution/g superabsorbent region.
The
superabsorbent region also preferably exhibits a water absorption capacity of
at least
20 g water/g superabsorbent region, more preferably at least 40 g water/g
superabsorbent region, most preferably at least 70 g water/g superabsorbent
region
within a period of 10 minutes.
The second region, which is free of superabsorbent polymer, can be of a
thickness sufficient to prevent the gel that is formed when the superabsorbent
polymer
is contacted with liquid from contacting the wearer. The region that is free
of
superabsorbent polymer can extend into the web to a depth sufficient to
provide a soft
feel to the touch. The thickness of the region of the web that is free of
superabsorbent
polymer can be sufficient to provide the function of fluid acquisition, fluid
distribution or a combination thereof.



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The nonwoven web is preferably a high loft nonwoven web, i.e., a nonwoven
web having a density of no greater than 0.01 gram per cubic centimeter
(g/cm3). The
three dimensional structure of a high loft nonwoven web matrix can include
passageways, e.g., channels, through which liquid (e.g., water, blood, and
urine) can
migrate, e.g., wick. When liquid contacts the superabsorbent polymer, the
superabsorbent polymer begins to expand. In some embodiments, the high loft
nonwoven web and the fibers of the high loft nonwoven web expand when
contacted
with liquid. The three-dimensional nature of the high loft matrix and the
expansion of
the web can accommodate liquid present in the web, liquid traveling into the
web, and
the swelling superabsorbent polymer. The expansion of the web enables the
nonwoven web to absorb a greater volume of liquid relative to a nonwoven web
having a relatively high density, and being essentially two-dimensional.
The three-dimensional matrix of the high loft nonwoven web also assists in
maintaining the swollen, i.e., gelled, superabsorbent polymer in the web
matrix.
Preferably the superabsorbent polymer gel does not migrate out of the high
loft matrix
and does not transfer or move during use of the absorbent article.
The nonwoven web exhibits good dry strength and maintains strength and
integrity when wet. Preferably the nonwoven web exhibits a dry tensile
strength of at
least 2000 g/25.4 mm, more preferably at least 2500 g/25.4 mm, most preferably
a dry
tensile strength of at least 3000 g/25.4 mm, and a wet tensile strength of at
least 150
g/25.4 mm, more preferably, at least 400 g/25.4 mm, most preferably at least
500
g/25.4 mm.
The nonwoven web is preferably a high loft nonwoven web having a basis
weight of greater than 22 g/mz for a web thickness (i.e., caliper) of at least
1
millimeter (mm), preferably at least 30 g/m2, more preferably at least 60
g/m2, more
preferably at least SO g/m2, most preferably at least 100 g/m2. The high loft
nonwoven web can vary in thickness depending on the application. Suitable high
loft
nonwoven webs have a thickness of at least 10 mm, more preferably at least 15
mm.
The high loft nonwoven web also has a density no greater than 0.01 g/cm3,
preferably
from about 0.002 g/cm3 to about 0.009 g/cm3, more preferably from about 0.007
g/cm3 to about 0.009 g/cm3. Other useful nonwoven webs with loft have a
density of
no greater than 0.025 g/cm3, and no greater than 0.023 g/cm3.
The nonwoven web includes synthetic polymer fibers of, e.g., polyester,
polyolefin (e.g., polypropylene, polyethylene, and copolymers of polyolefins
and



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polyesters), polyamide, polyurethane, polyacrylonitrile, and combinations
thereof
including copolymers thereof, bicomponent (e.g., sheath core) fibers and
combinations thereof. The nonwoven web can also include a region that includes
fibers of a different polymer, polymers or combinations of polymers relative
to the
fiber composition of another region. The superabsorbent region of the web can
include superabsorbent polymer fibers. Preferably the nonwoven web is
resilient and
includes resilient fibers (e.g., polyester fibers). The fibers can be curly
and
mechanically and physically entangled.
Nonwoven webs can be formed using a variety of methods including, e.g., air-
laying, wet laying, garneting and carding, melt blown, melt spinning, and
spunbond
techniques, and combinations thereof. A variety of bonding systems can be used
to
bond fibers of a nonwoven web including, e.g., thermal bonding, resin bonding,
mechanical bonding (e.g., needle punch and hydroentangling), and combinations
thereof.
The superabsorbent polymer present in the first region of the nonwoven web is
capable of absorbing water in an amount many times its own weight. Preferably
the
superabsorbent polymer is capable of absorbing water in an amount of at least
100
times its own weight, and can be capable of absorbing at least 150 times its
own
weight, more preferably at least 200 times its own weight. The superabsorbent
polymer present in the superabsorbent region can be formed in situ, i.e., in
place on
the nonwoven web, e.g., from an aqueous superabsorbent polymer composition.
The aqueous superabsorbent polymer composition includes a superabsorbent
polymer precursor (e.g., an alkali soluble polyelectrolyte) and a crosslinking
agent.
As the aqueous superabsorbent polymer composition dries, the superabsorbent
polymer precursor crosslinks to form the superabsorbent polymer. Particularly
useful
superabsorbent polymer precursors include polymers of water soluble monomers.
Preferably the polymer is an at least partially neutralized polymer derived
from a,13-
ethylenically unsaturated mono- or dicarboxylic acid monomers, acid anhydride
monomers or a combination thereof, and a crosslinking agent. Useful water
soluble
a,13-ethylenically unsaturated mono- or dicarboxylic acid monomers include,
e.g.,
acrylic acid, methacrylic acid, crotonic acid, malefic acid, malefic
anhydride, itaconic
acid, fumaric acid and combinations thereof.
The phrase "partially neutralized" refers to the presence of at least some
neutralized carboxylic acid groups in the superabsorbent polymer precursor.
The



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superabsorbent polymer precursor can be fully neutralized. The phrase "fully
neutralized" means that the superabsorbent polymer precursor composition
exhibits a
pH greater than 7. The superabsorbent polymer precursor composition is
adjusted to a
pH from about 5 to about 6 using an alkali metal hydroxide examples of which
include sodium hydroxide, calcium hydroxide, potassium hydroxide and
combinations
thereof. A metal alkoxide can be used in place of the metal hydroxide examples
of
which include calcium hydroxide and potassium hydroxide. It is preferred to
first
neutralize from about 50 % to about 95 % of the acid groups, more preferably
from
about 65 % to about 85 % of the acid groups, most preferably from about 75 %
to 85
% of the acid groups with an alkali metal hydroxide to a pH of from 2 to 6,
more
preferably a pH from 5 to 6, and then further neutralize the superabsorbent
polymer
precursor with a volatile fugitive alkaline component (i.e., a base) to a pH
greater than
7, more preferably from greater than 7 to 10, most preferably from greater
than 7 to 8,
to achieve a fully neutralized, i.e., 100 % of the acid groups are
neutralized,
superabsorbent polymer precursor.
Suitable fugitive alkaline components include, e.g., ammonia, triethylamine,
dimethylethylamine, and combinations thereof The volatile fugitive alkaline
component dissipates as the aqueous composition dries. The dissipation of the
base
liberates a sufficient portion of the carboxylate groups to the free acid,
i.e., carboxylic,
form. The carboxylic groups are then available for reaction with the
crosslinking
agent.
The viscosity of the aqueous superabsorbent polymer composition is
preferably from about 50 centipoise (cps) to about 50,000 cps, preferably from
about
100 cps, to about 30,000 cps, preferably from about 100 cps to about 20,000
cps,
preferably from about 100 cps to about 10,000 cps, preferably from about 100
cps to
about 5,000 cps, preferably from about 100 cps to about 2,500 cps at a solids
content
of about 23 %. Preferred aqueous superabsorbent polymer compositions have a
viscosity suitable for application using spray techniques, saturation
techniques, and
coating techniques.
The aqueous superabsorbent polymer composition preferably includes from
about 5 % by weight to about 65 % by weight, preferably from about 10 % by
weight
to about 50 % by weight, more preferably from about 20 % by weight to about 40
by weight solids.



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Useful aqueous superabsorbent polymer compositions are described in, e.g.,
PCT Patent Application No. WO 00/61642 (Anderson et al.) and U.S. Patent No.
5,693,707 (Cheng et al.) and incorporated herein. A useful commercially
available
aqueous superabsorbent polymer composition is available under the trade
designation
FULATEX PD-8081-H from H.B. Fuller Company (Vadnais Heights, Minnesota).
A sufficient amount of crosslinking agent is added to the aqueous
superabsorbent polymer composition to achieve the superabsorbent polymer.
Preferably the crosslinking agent reacts with the functional groups on the
superabsorbent polymer precursor in less than 24 hours during drying at
ambient (i.e.,
about 20°C) temperature or a higher temperature. Useful crosslinking
agents include
any substance that will react with the hydrophilic groups of the aqueous
solution
polymer. Useful crosslinking agents include, e.g., zirconium ions, ferric
aluminum
ions, chromic ions, titanium ions and combinations thereof, and aziridine. A
variety
of suitable crosslinking agents are described in U.S. Patent No. 4,090,013 and
incorporated herein. One example of a useful commercially available
crosslinking
agent is BACOTE 20 ammonium zirconyl carbonate available from Magnesium
Elektron Inc. (Flemington, New Jersey). Preferably the composition includes
crosslinking agent in an amount of from about 2 parts to about 24 parts, more
preferably from about 4 parts to about 14 parts, most preferably from about 6
parts to
about 10 parts based on the weight of the dry ingredients.
The composition can also include chain transfer agents to alter the molecular
weight of the superabsorbent polymer. Suitable chain transfer agents include,
e.g.,
sodium hypophosphite, thioglycolic acid, mercaptans including, e.g., primary
octyl
mercaptan, 2-mercaptoethanol, n-dodecylmercaptan, n-octylmercaptan, t-dodecyl
mercaptan, mercaptoethanol, iso-octyl thioglycolurate, mercapto carboxylic
acids
having 2 to 8 carbon atoms, and their esters, examples of which include 3-
mercapto
propionic acid and 2-mercapto propionic acid, halogenated hydrocarbons
including,
e.g., carbonbromo compounds (e.g., carbon tetrabromide and
bromotrichloromethane)
and combinations thereof. The chain transfer agent can be present in the
aqueous
superabsorbent polymer composition in an amount no greater than 5 % by weight,
preferably from 1 % by weight to about 4 % by weight, more preferably from 1 %
by
weight to about 3 % by weight.
The composition can also include other components including, e.g., wetting
agents, defoamers, plasticizers, binder agents, and combinations thereof.



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The superabsorbent polymer is applied to the high loft web in the form of an
aqueous superabsorbent polymer composition that, upon drying, crosslinks to
form
the superabsorbent polymer.
The aqueous superabsorbent polymer composition can be applied to the web
using a variety of techniques including, e.g., soaking, spraying, printing,
coating, and
combinations thereof. Preferably the superabsorbent region of the web is
impregnated
with superabsorbent polymer, i.e., the superabsorbent polymer exists
throughout the
web matrix.
The aqueous superabsorbent polymer composition can be dried according to
various methods including, e.g., air (including, e.g., circulating air), heat,
microwave
radiation (i.e., radiation in the frequency range of 300 MHz to 300,000 MHz
including, e.g., 915 MHz, 2450 MHz, 5800 MHz, and 22,155 MHz,), radio
frequency
radiation, ultraviolet light radiation, electron beam radiation, and
combinations
thereof (e.g., by passing the nonwoven web through a circulating air oven).
The superabsorbent nonwoven web is useful in absorbent articles including,
e.g., disposable absorbent articles, i.e., articles that are designed to be
disposed of
after use. Useful applications for the superabsorbent nonwoven web include,
e.g., as
the core or a component of the core of various absorbent articles including,
e.g.,
disposable diapers, feminine hygiene products (e.g., sanitary napkins and
panty
liners), bandages, wound care products, surgical pads, incontinence articles
(e.g.,
adult incontinence pads, and incontinence undergarments), garments (e.g.,
training
pants, pull-on garments), breast pads, bibs, perspiration pads (e.g.,
underarm, wrist
and head), collar inserts, shoe inserts, and hat inserts (e.g., hat band). The
superabsorbent nonwoven can be used in combination with other core materials
including, e.g., cellulose fibers and other fluff materials. The
superabsorbent
nonwoven can be present in an absorbent article in the form of a continuous
web,
positioned in discreet regions on another component of an absorbent article,
and
combinations thereof. The superabsorbent nonwoven can be located in various
positions and configurations on or in an article including e.g., randomly or
in a pattern
(e.g., strips), and combinations thereof. In one embodiment, the
superabsorbent
nonwoven is positioned such that the superabsorbent region is in contact with
cellulose fibers. In other embodiments, the article includes multiple
superabsorbent
nonwoven webs positioned in alternating relation with regions of cellulose
fibers.



CA 02473950 2004-07-21
WO 03/065953 PCT/US03/03267
The superabsorbent nonwoven can also be maintained in position in or on an
article
through an adhesive composition.
The article in which the superabsorbent nonwoven web is incorporated can
optionally include other components including, e.g., a body fluid pervious top
sheet,
an acquisition layer, a second absorbent layer (e.g., a second core or fibrous
layer), a
body fluid impermeable back sheet, and combinations thereof.
The top sheet can be compliant, soft feeling, and non-irritating to the
wearer's
skin. The top sheet can be liquid pervious permitting liquids (e.g., urine) to
penetrate
through its thickness. A suitable top sheet may be manufactured from a wide
range of
materials including, e.g. woven and nonwoven webs, films, porous foams, porous
films including, e.g., perforated film (e.g., film of polyethylene,
polypropylene or a
combination thereof). The top sheet can be hydrophobic to isolate the wearer's
skin
from fluids that have passed through the top sheet and are contained in the
absorbent
core.
The acquisition layer preferably is capable of dispersing liquid to the
surface
of the core.
The second absorbent layer may include loose fibers, fibers held together
through a binder, compressed fibers and combinations thereof. The fibers of
the
second absorbent layer can be of a variety of compositions including, e.g.,
natural
fibers (e.g., wood pulp, jute, cotton, silk and wool and combinations
thereof),
synthetic fibers including (e.g., nylon, rayon polyester, acrylics,
polypropylenes,
polyethylene, polyvinyl chloride, polyurethane, and combinations thereof), and
combinations thereof.
The back sheet can be positioned away from a wearer's skin and prevents the
liquids contained in the absorbent core from wetting articles that contact the
absorbent
article. The back sheet can be impervious to liquid and permeable to moisture
vapor.
The superabsorbent nonwoven web can be disposed between any two
components of an absorbent article including, e.g., between the body fluid
pervious
top sheet and a body fluid impermeable back sheet, between an acquisition
layer and a
body fluid impermeable back sheet, and combinations thereof. The
superabsorbent
regions of the nonwoven web can be in contact with cellulose fibers. The
superabsorbent nonwoven web can also be located in contact with a wearer.
11



CA 02473950 2004-07-21
WO 03/065953 PCT/US03/03267
The invention will now be described further by way of the following
examples. All parts, ratios, percents and amounts stated in the Examples are
by
weight unless otherwise specified.
EXAMPLES
Test Procedures
Test procedures used in the examples include the following.
Total Water Absorbency
The total water absorbency (g/g) is the weight of tap water in grams (g) that
each gram of a 100 cm2 sample of composite absorbs in 10 minutes. A 100 cm2
(10
cm x 10 cm) sample of dry composite is weighed (WD). The sample is then
submerged in tap water for 10 minutes. The wet and swollen composite is placed
on a
pre-weighted metal screen (WS) for one minute. The excess water present in the
sample is allowed to drain. The wet sample and the screen are then weighed
(WW).
The total water absorbency (Twa) is calculated according to the following
equation:
Twa = [(WW - WS) - WD~/WD
and reported in g absorbed water/g composite
Total 0.9 % Saline Solution Absorbency Under Load
The total 0.9 % saline absorbency (g/g) is the weight of 0.9 % saline (g) that
each gram of a 100 cmz sample of composite absorbs in 10 minutes. The total
0.9%
saline absorbency is determined by weighing a 100 cm2 (10 cm x 10 cm) sample
of
dry composite (WD). The sample is placed in a receptacle and a metal mesh
screen
and brass weights are placed on top of the sample. Both the metal screen and
the
weights have the same size as (i.e., are coextensive with) the sample, and the
total
weight of the metal mesh screen and brass weights must exert 0.3 psi on the
sample.
A sufficient amount of 0.9 % saline solution is poured into the receptacle to
submerge
the absorbent sample. After 10 minutes, the weight and metal screen are
removed.
The absorbent sample (WW) is then promptly weighed.
The total 0.9 % saline absorbency under load (AUL) is calculated according to
the following equation:
0.9 % Saline AUL = (WW - WD)/WD
and reported in g absorbed 0.9 % saline solution/g composite
12



CA 02473950 2004-07-21
WO 03/065953 PCT/US03/03267
Dry Tensile Strength
A 4 inch x 1 inch strip of sample composite is cut and %z inch strips of
masking tape are wrapped at each of the 1 inch wide ends of the composite
strip. The
composite strip is then placed between the jaws of an Instron tester (Instron
Corp.,
Canton, Massachusetts) and tensile strength is measured at a 12 inch/min cross-
head
speed. The average tensile strength of 5 samples is reported as the Dry
Tensile
Strength in g/in.
Wet Tensile Strength
A 4 inch x 1 inch strip of sample composite is cut and %2 inch strips of
masking tape are wrapped at each of the 1 inch wide ends of the composite
strip. The
composite strip is then soaked in water for 5 minutes, gently patted dry of
excess
water and then promptly tested by placing the sample between the jaws of an
Instron
tester. Tensile strength is measured at a 12 inch/min cross-head speed. The
average
tensile strength of 5 samples is reported as the Wet Tensile Strength in g/in.
Superabsorbent Polymer (SAP) Loading
The percent superabsorbent polymer present in the composite is determined by
weighing the web prior to treatment with superabsorbent polymer, weighing the
dried
composite after treatment with superabsorbent polymer, subtracting~to find the
weight
of superabsorbent polymer in the composite, and dividing the weight of the
superabsorbent polymer by the total weight of the composite.
The results are reported as % SAP.
Controls 1 and 2
Samples were prepared by saturating polyester fiber nonwoven webs having
the properties set forth in Tables 1 and 2 with an aqueous superabsorbent
polymer
composition of 95 parts FULATEX PD-8081-H aqueous superabsorbent polymer
(23°/~ solids) (H.B. Fuller Company, Vadnais Heights, Minnesota) and 5
parts
BACOTE 20 ammonium zirconyl carbonate (40 % active as supplied) (Magnesium
Elektron Inc., Flemington, New Jersey). The webs were dried and weighed to
determine % superabsorbent polymer present in the composite.
13



CA 02473950 2004-07-21
WO 03/065953 PCT/US03/03267
Examples 1-4
Superabsorbent composites were prepared by saturating polyester fiber
nonwoven webs having the properties set forth in Table 1 with an aqueous
superabsorbent polymer composition of 95 parts FULATEX PD-8081-H aqueous
superabsorbent polymer (23% solids) and 5 parts BACOTE 20 ammonium zirconyl
carbonate (40 % active as supplied) (Magnesium Elektron Inc., Flemington, New
Jersey). The webs were dried and weighed to determine % superabsorbent polymer
present in the composite.
The samples of Control 1 and Examples 1-4 were tested according to the
above-described methods to determine wet and dry tensile strength. The weight
and
thickness of the samples were also determined. The results are reported in
Table 1.
Table 1
Sample Basis Tluckness% SAP Dry Wet TensileTensile


Weight (mm) CompositeCompositeStrengthStrength


(g/mz) Basis Thiclrness


(Dry) (Wet)


Weight (~,~,)


(g/mz) g/25.4 g/25.4


mm mm


Controll 22 0.06 82 122 1.5 2820 480


Example 30 2 83 176 2.3 2430 385
1


Example 60 5 73 222 11 2480 410
2


Example 60 5 90 600 13 2660 460
3


Example 100 14 76 416 16 2870 406
4


Examples 5-17
Superabsorbent composites were prepared according to Example 1 with the
exception that the nonwoven webs had the basis weight and density set forth in
Table
2 and the amount of superabsorbent polymer applied to the web was controlled
to
achieve a composite having the % superabsorbent polymer indicated in Table 2.
The samples of Controls l and 2 and Examples 5-17 were tested according to
the above-described methods to determine the water absorbent capacity and 0.9
Saline absorbency under load (AUL). The results are reported in Table 2.
14



CA 02473950 2004-07-21
WO 03/065953 PCT/US03/03267
Table 2
Sample BasisDensityUntreated SAP-Containing site
Web Compo


Weight(g/cm3)Water 0.9 % % SAP Water 0.9 % Saline
(g/m2) AbsorbencySaline AbsorbencyAUL
(g water/gAUL (g water/g(g 0.9
~ (g 0.9% composite)% saline
composite)saline solution/g
solution/g composite)
composite)


Controll 22 ND 4 2 82 18 10


Example 30 0.0227 6 4 83 24 12



Example 30 0.0227 6 4 71 18 10
6


Example 30 0.0227 6 4 57 12 14
7


Example 30 0.0227 6 4 52 10 14
8


Example 60 0.0024 10 5 87 31 12
9


Example 60 0.0076 18 5 90 65 17



Example 60 0.0076 18 5 79 46 15
11


Example 60 0.0076 18 5 73 37 15
12


Example 60 0.0076 18 5 62 31 13
13


Example 60 0.0076 18 5 50 28 14
14


Example 100 0.0083 20 7 76 34 18



Example 100 0.0083 20 7 59 33 17
16


Example 100 0.0083 20 7 51 31 21
17


Control2 300 0.046 30 15 50 22 12


ND = not determined
5 Example 18
A polyester fiber highloft nonwoven web, 10 cm x 10 cm x 1.1 cm in
dimension, weighing 0.86 g, and having a density of 0.0078 g/cm3 (Carpenter
Company, Temple, Texas) was saturated with PD-8081-H aqueous superabsorbent
polymer (H.B. Fuller Company), and dried. The treated web had a superabsorbent
10 polymer loading of 78.6 %. The treated web was then contacted with seventy-
five ml
of 0.9 % saline solution applied at a rate of 7 ml/second using a variable
flow pump
manufactured by Manostat, a Division of Barnant Co. (Barrington, Illinois).



CA 02473950 2004-07-21
WO 03/065953 PCT/US03/03267
The web absorbed 75 ml of 0.9 % saline solution. No leakage or overflow
was observed. The surface of the web was wet to the touch. Gelled
superabsorbent
polymer was visible at the surface.
Example 19
A polyester fiber highloft nonwoven web, 10 cm x 10 cm x 1.5 cm in
dimension, weighing 0.96 g, and having a density of 0.0064 g/cm3 (Carpenter
Company) was obtained for use in Example 19. A first region of the web was
saturated with PD-8081-H aqueous superabsorbent polymer such that the region
containing superabsorbent polymer extended from a first major surface of the
web
into a portion of the depth of the web. The aqueous superabsorbent polymer was
allowed to dry. The superabsorbent polymer loading on the web was 85.8 %. A
second region extending from the second major surface of the web opposite the
first
major surface and the first region into a portion of the depth of the web was
free of
superabsorbent polymer. The treated web was placed between two glass plates
such
that the region of the web that the second major surface, i.e., the region
that was free
of superabsorbent polymer, was in contact with the top glass plate. The top
glass
plate included a hole. Seventy-five ml of 0.9 % saline solution was applied to
the web
through the hole at a rate of 7 ml/second using a variable flow pump
manufactured by
Manostat, a Division of Barnant Co. (Barrington, Illinois).
Example 20
A polyester fiber highloft nonwoven web, 9.8 cm x 9.5 cm x 2.0 cm in
dimension, weighing 1.66 g and having a density of 0.0089 g/cm3 (Carpenter
Company) was obtained for use in was obtained for Example 20. A first region
of the
web was saturated with PD-8081-H aqueous superabsorbent polymer such that the
region containing superabsorbent polymer extended from a first major surface
of the
web into a portion of the depth of the web. The aqueous superabsorbent polymer
was
allowed to dry. The superabsorbent polymer loading on the web was 65.6 %. A
second region extending from the second major surface of the web opposite the
first
major surface and the first region into a portion of the depth of the web was
free of
superabsorbent polymer. The treated web was placed between two glass plates
such
that the region of the web that the second major surface, i.e., the region
that was free
of superabsorbent polymer, was in contact with the top glass plate. The top
glass
16



CA 02473950 2004-07-21
WO 03/065953 PCT/US03/03267
plate included a hole. Seventy-five ml of 0.9 % saline solution was applied to
the web
through the hole at a rate of 7 ml/second using a variable flow pump
manufactured by
Manostat, a Division of Barnant Co. (Barrington, Illinois).
The webs of Examples 19 and 20 absorbed the 75 ml of 0.9 % saline solution.
No leakage or overflow was observed. The second major surface of the webs
exhibited an overall dry feeling except in the area where the saline solution
was
introduced into the web. No gelled superabsorbent polymer was visible on the
second
major surface of the webs.
Other embodiments are within the claims. Although the superabsorbent
composite has been described with respect to disposable article cores, the
superabsorbent composite is also useful in various other absorbent article
applications
including, e.g., wipes, towels, facial tissue, mops, and agricultural
applications (e.g.,
to maintain moisture). The composite can also be combined with at least one
other
nonwoven web in a layered construction.
What is claimed is:
17

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Administrative Status

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Administrative Status

Title Date
Forecasted Issue Date Unavailable
(86) PCT Filing Date 2003-02-04
(87) PCT Publication Date 2003-08-14
(85) National Entry 2004-07-21
Dead Application 2009-02-04

Abandonment History

Abandonment Date Reason Reinstatement Date
2008-02-04 FAILURE TO PAY APPLICATION MAINTENANCE FEE
2008-02-04 FAILURE TO REQUEST EXAMINATION

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $400.00 2004-07-21
Registration of a document - section 124 $100.00 2004-10-19
Maintenance Fee - Application - New Act 2 2005-02-04 $100.00 2005-01-27
Maintenance Fee - Application - New Act 3 2006-02-06 $100.00 2006-01-30
Maintenance Fee - Application - New Act 4 2007-02-05 $100.00 2007-01-18
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
H.B. FULLER LICENSING & FINANCING, INC.
Past Owners on Record
MEHAWEJ, FOUAD D.
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Cover Page 2004-09-22 1 31
Abstract 2004-07-21 1 52
Claims 2004-07-21 2 79
Description 2004-07-21 17 977
Fees 2005-01-27 2 84
Correspondence 2004-09-18 1 27
Fees 2006-01-30 1 47
PCT 2004-07-21 8 281
Assignment 2004-07-21 3 90
Assignment 2004-10-19 4 116
Correspondence 2005-04-22 1 17
Fees 2007-01-18 1 50