U.S. patent application number 10/744339 was filed with the patent office on 2004-07-15 for substrates comprising flocked fibers of superabsorbent polymer.
Invention is credited to Lasko, Vincent P..
Application Number | 20040137190 10/744339 |
Document ID | / |
Family ID | 23403642 |
Filed Date | 2004-07-15 |
United States Patent
Application |
20040137190 |
Kind Code |
A1 |
Lasko, Vincent P. |
July 15, 2004 |
Substrates comprising flocked Fibers of superabsorbent polymer
Abstract
A substrate having flocked fibers of superabsorbent polymer
thereon is provided. The substrate may be one of a variety of
materials, such as nonwoven materials, polymer films, apertured
films, absorbent layers, netting, woven fabrics, foams, reticulated
films and the like.
Inventors: |
Lasko, Vincent P.; (New
Egypt, NJ) |
Correspondence
Address: |
PHILIP S. JOHNSON
JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
23403642 |
Appl. No.: |
10/744339 |
Filed: |
December 23, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10744339 |
Dec 23, 2003 |
|
|
|
09356948 |
Jul 19, 1999 |
|
|
|
6692811 |
|
|
|
|
Current U.S.
Class: |
428/90 ;
604/367 |
Current CPC
Class: |
Y10T 428/23943 20150401;
A61F 2013/530613 20130101; D04H 11/00 20130101; A61F 13/51121
20130101; E03F 5/14 20130101; A61F 13/53 20130101 |
Class at
Publication: |
428/090 ;
604/367 |
International
Class: |
B05D 001/14; A61F
013/15 |
Claims
I claim:
1. A substrate having flocked fibers of superabsorbent polymer
thereon.
2. The substrate of claim 1, wherein the fibers of superabsorbent
polymer are selected from the group consisting of polyacrylates,
grafted cellulose, and maleic acid.
3. The substrate of claim 1 further comprising flocked fibers of a
second hydrophilic material thereon.
4. The substrate of claim 3, wherein the second hydrophilic
material is selected from the group consisting of wettable
materials, absorbent materials, and mixtures thereof.
5. The substrate of claim 1 further comprising flocked fibers of a
hydrophobic material thereon.
6. The substrate of claim 5, wherein the hydrophobic material is
selected from the group consisting of polyesters, olefins, and
mixtures thereof.
7. The substrate of claim 1, wherein the fibers comprise a
combination of superabsorbent polymer, another hydrophilic
material, and a hydrophobic material.
8. The substrate of claim 1, wherein said substrate is selected
from the group consisting of nonwoven materials, polymer films,
breathable materials, apertured films, absorbent layers, netting,
woven fabrics, foams, and reticulated films.
9. An apertured film having flocked fibers of superabsorbent
polymer thereon.
10. The apertured film of claim 9 having a top surface and an
underside surface and comprising a plurality of apertures, wherein
said flocked fibers are adhered to the underside surface of the
film.
11. The apertured film of claim 10, wherein each of said apertures
originates in the top surface of the film and is defined by a
sidewall projecting from the underside surface of the film, each
sidewall having an inner surface and an outer surface, wherein said
flocked fibers are also adhered to the outer surfaces of the
aperture sidewalls.
12. The apertured film of claim 9 having a top surface and an
underside surface and comprising a plurality of apertures, wherein
said flocked fibers are adhered to the top surface of the film.
13. The apertured film of claim 9, wherein the fibers of
superabsorbent polymer are selected from the group consisting of
polyacrylates, grafted cellulose, and maleic acid.
14. The apertured film of claim 9 further comprising flocked fibers
of a second hydrophilic material thereon.
15. The apertured film of claim 14, wherein the second hydrophilic
material is selected from the group consisting of wettable
materials, absorbent materials, and mixtures thereof.
16. The apertured film of claim 9 further comprising flocked fibers
of a hydrophobic material thereon.
17. The apertured film of claim 16, wherein the hydrophobic
material is selected from the group consisting of polyesters,
olefins and mixtures thereof.
18. The apertured film of claim 9, wherein the fibers comprise a
combination of superabsorbent polymer, a second hydrophilic
material, and a hydrophobic material.
19. An absorbent article comprising a substrate having flocked
fibers of superabsorbent polymer thereon.
20. The absorbent article of claim 19, wherein the substrate is
selected from the group consisting of nonwoven materials, polymer
films, breathable materials, apertured films, absorbent layers,
netting, woven fabrics, foams, and reticulated films.
21. The absorbent article of claim 19, wherein the substrate is an
apertured film.
22. A sanitary napkin according to claim 19.
23. A pantiliner according to claim 19.
Description
[0001] The present invention relates to substrates, particulartly
for use in absorbent articles, comprising flocked fibers of
superabsorbent plymer.
BACKGROUND OF THE INVENTION
[0002] The use of superabsorbent polymers in absorbent articles,
such as sanitary napkins, pantiliners, diapers, and incontinence
pads is known. Superabsorbent polymers enhance the liquid
management properties of absorbent articles, such as capacity and
retention of fluids. They are added to the components of absorbent
articles in the form of particles or fibers, but most often in the
form of particles. Most commercially available processing equipment
is designed to handle superabsorbent polymer particles rather than
fibers, since fibers are more difficult to disperse than particles
and tend to collapse.
[0003] Superabsorbent polymers are typically found in the absorbent
core of an absorbent article, where they are easily incorporated.
However, it would be desirable to be able to employ superabsorbent
polymers in a convenient manner in and on other kinds of
substrates, such as other nonwoven materials, polymer films,
apertured films, netting, woven fabrics, foams, reticulated films,
and the like.
[0004] Flocking is a technique by which fibers are fixed in a
vertical position on a substrate, and is primarily used in the
fabric industry. However, EP 0 737 462 A1 discloses a laminated
material to cover the outside of an absorbent product,
characterized in that at least one portion of the surface of the
laminated material bears a layer of fibers applied by flocking. The
flocked fibers are thereby located on the external surface of the
absorbent product in order to give the absorbent product improved
tactile properties over products that employ plastic films against
the skin. EP 0 737 462 A1 discloses that the external surface to
which the flocked fibers may be applied may be a perforated cover.
The cover may be perforated before or after the flocking is
applied, but is preferably perforated before flocking.
[0005] Applicant has discovered that fibers of superabsorbent
polymer may be advantageously adhered to a variety of substrates by
flocking. According to the invention, when flocked fibers of
superabsorbent polymer are applied to a substrate, they stand in an
upright, vertical manner on the surface. Such an orientation allows
the flocked fibers of superabsorbent polymer to absorb an increased
amount of fluid compared with unflocked fibers of superabsorbent
polymer, i.e., fibers compressed horizontally. This in turn makes
substrates comprising flocked fibers of superabsorbent polymer
particularly attractive for use in absorbent articles of all
types.
[0006] Applicant has also discovered that flocked fibers of
superabsorbent polymer may advantageously be applied to the surface
of an apertured film. In particular, an apertured film comprising
flocked fibers of superabsorbent polymer on its underside surface,
and additionally on the outer surfaces of the aperture sidewalls,
provides an improved cover or other component of an absorbent
article. Materials and manufacturing technology have enabled the
development of nonwoven fabric and polymer apertured films that
mimic the feel of woven fabric quite well. And although many
variations of apertured films exist in the art, improved apertured
films are always desired, particularly those having improved fluid
transport properties.
SUMMARY OF THE INVENTION
[0007] The present invention provides substrate having flocked
fibers of superabsorbent polymer thereon, as well as an absorbent
article comprising such as substrate.
[0008] The invention also provides an apertured film having flocked
fibers of superabsorbent polymer thereon. The flocked fibers of
superabsorbent polymer may be on the top surface or the underside
surface of the apertured film, or on the sidewalls of the apertures
themselves.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a magnified view of the top surface of an
apertured film with flocked fibers of superabsorbent polymer,
rayon, and polyester adhered to the underside thereof.
[0010] FIG. 2 is a magnified view of the underside surface of the
apertured film in FIG. 1.
[0011] FIG. 3 depicts an absorbent article (pantiliner) having a
cover comprising flocked fibers of superabsorbent polymer according
to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] According to the invention, fibers of superabsorbent polymer
are adhered to a substrate by flocking. The substrate may be one of
a variety of materials, such as nonwoven materials, polymer films,
breathable materials, apertured films, absorbent layers, netting,
woven fabrics, foams, and reticulated films. Preferably, the
substrate is selected from the group consisting of nonwoven
materials, polymer films, breathable materials, apertured films,
and absorbent layers. Other substrates suitable for flocking of
superabsorbent polymer thereon will be recognized by those skilled
in the art, and the invention is not intended to be limited to any
particular kind of substrate.
[0013] A variety of nonwoven materials are known and used in the
field of absorbent articles. They are typically made by entangling,
for example via carding or hydroentangling, thermoplastic fibers,
such as polyolefin fibers i.e., polyethylene and polypropylene,
polyester fibers, polyamide fibers (including nylon), polyacrylic
fibers, and the like into a web.
[0014] Examples of polymer films include polyethylene,
polypropylene, polyester, cellulose, cellophane, polyurethane,
cross-linked polyethylene, polyethylene oxide, and polyvinyl
alcohol.
[0015] Examples of breathable materials include polyurethane films
and microporous films in which microporosity is created by ionizing
radiation or by leaching out of soluble inclusions using aqueous or
nonaqueous solvents. Single or multiple layers of permeable films,
fabrics, and combinations thereof that provide a tortuous path,
and/or whose surface characteristics provide a liquid surface
repellent to the penetration of liquids may also be used.
[0016] An apertured films is any type of film having apertures in
it. Such films may be made from nonwoven materials, polymer films,
breathable materials, and so forth.
[0017] Absorbent layers include, for example, those made of loosely
associated absorbent hydrophilic material such as cellulose fibers,
including wood pulp, regenerated cellulose fibers or cotton fibers,
or other absorbent materials generally known in the art, including
acrylic fibers, polyvinyl alcohol fibers, peat moss.
[0018] The substrate is preferably used as part of an absorbent
article, for example a sanitary napkin, pantiliner, diaper,
incontinence pad, interlabial article, wound dressing, baby wipe,
feminine hygiene wipe, nursing pad, or other similar product for
absorbing bodily fluids. Preferably, the absorbent article is a
sanitary napkin or a pantiliner. Such sanitary napkin or pantiliner
may have an approximately rectangular, oval, dogbone, or peanut
shape. Depending on the nature of the absorbent article, its size
may vary. For example, sanitary napkins typically have a caliper of
about 1.4 to about 5 mm, a length of about 3 to about 16 inches,
and a width of about 1 to about 5 inches. Pantiliners typically
have a caliper of less than about 0.2 inches, a length of less than
about 8 inches, and a width of less than about 3 inches.
[0019] Fibers of superabsorbent material are applied to one or more
surfaces of the substrate by the process of flocking. Methods of
flocking fibers onto a surface are known in the art of fabric
manufacture. See for example, U.S. Pat. Nos. 2,527,501; 2,691,611;
3,436,442; and 3,672,929. Typically, a substrate, such as a cover,
is coated with adhesive on all or a portion of its surface. The
coated substrate is then passed through a fiber metering station in
which an electrostatic field is maintained around the substrate,
using for example electrodes situated above and below the
substrate. The fibers are applied to the adhesive on the substrate
in the presence of the electrostatic field, which orients the
fibers perpendicular to the substrate as they contact the adhesive.
The substrate is then heated, polymerizing the adhesive and
anchoring the fibers. Unattached fibers may be vacuumed away.
[0020] Preferably, the adhesive employed to attach the fibers to
the internal surface is a polymerizable resin, such as modified
acrylic water based compounds, for example FLEXBOND 974, 977, 983,
and 986 commercially available from Air Products, CARBOTAC
Adhesives (PSAs) commercially available from B F Goodrich, and
CARBOBOND Adhesives (non-PSAs) also commercially available from B F
Goodrich.
[0021] A variety of superabsorbent polymers are known, and any of
these may be used according to the invention. Superabsorbent
polymer fibers are hydrophilic fibers that are swellable and
capable of absorbing greater than about 5 grams per gram (of fiber
weight) of 1% saline solution. Examples of superabsorbent polymer
fibers are polyacrylate fibers, fibers of grafted cellulose, and
fibers of maleic acid. Preferred types of superabsorbent polymer
fibers include OASIS Type 101, commercially available from
Technical Absorbents Limited and CAMELOT, commercially available
from Camelot, Alberta, Canada. The substrate may additionally
contain superabsorbent polymer in a form other than as flocked
fibers, such as in the form of particles, or non-flocked
fibers.
[0022] Flocked fibers of a second hydrophilic material, a
hydrophobic material, or combinations thereof may also be adhered
to the substrate with fibers of the superabsorbent polymer. As used
herein, "a second hydrophilic material" means an absorbent material
or wettable material other than a superabsorbent polymer. Wettable
materials are typically hydrophobic materials that have been
treated with a wetting agent to render them hydrophilic. Examples
of wettable materials include bicomponent fibers, polypropylene
fibers, and polyester fibers that have been treated for example
with surfactants. Preferred wettable materials are polyester
fibers, such as DuPont-Akra Polyester Type 11A Bright commercially
available from DuPont Company treated with a surfactant such as
Tween 20 commercially available from ICI Americas Inc. Absorbent
materials are hydrophilic materials that both that have an affinity
for and absorb fluids, such as rayon, acrylics, nylon, polyvinyl
alcohol, and natural or regenerated cellulosics. A preferred type
of absorbent material is rayon.
[0023] Hydrophobic materials include certain olefins and large
denier polyester fibers, preferably having a denier of at least 3,
more preferably at least 6. A preferred hydrophobic material is 15
denier polyester commercially available from DuPont Company.
[0024] In a preferred embodiment of the invention, the flocked
fibers comprise a combination of superabsorbent polymer and a
second hydrophilic material (i.e., a wettable material, absorbent
material, or both). In this embodiment, fluid is quickly absorbed
by the fibers of second hydrophilic material and then transferred
to the fibers of superabsorbent polymer. Although the fibers of
superabsorbent polymer absorb more slowly than the fibers of second
hydrophilic material, the superabsorbent polymer fibers have
overall higher capacity and increased fluid retention.
[0025] In this embodiment, the amount of superabsorbent polymer in
the combined superabsorbent polymer/second hydrophilic material
fibers is typically from about 5 to about 95 percent by weight,
preferably from about 30 to about 70 percent by weight. The flocked
fibers of superabsorbent polymer may be uniformly dispersed in the
fibers of second hydrophilic material, or the fibers of
superabsorbent polymer and second hydrophilic material may be
adhered to the substrate in patterns.
[0026] In a particularly preferred embodiment of the invention, the
flocked fibers comprise a combination of superabsorbent polymer, a
second hydrophilic material, and a hydrophobic material. Again,
fluid is quickly absorbed by the fibers of the second hydrophilic
material and transferred to the higher fluid capacity
superabsorbent polymer fibers. The fibers of hydrophobic material
absorb little or no fluid and therefore advantageously maintain
their physical integrity, such as to minimize wet collapse. The
hydrophobic fibers support the fibers of superabsorbent polymer and
second hydrophilic material as the latter absorb fluid and lose
their rigidity. Moreover, due to the upright support of the
hydrophobic fibers, less pressure is placed on the substrate, also
increasing the absorbent capacity of the substrate. In this manner,
the overall structure and physical integrity of the substrate is
preserved.
[0027] In this embodiment, the amount of superabsorbent polymer in
the combined superabsorbent polymer/second hydrophilic
material/hydrophobic material fibers is typically from about 5 to
about 95 percent by weight, preferably from about 30 to about 70
percent by weight. The fibers of superabsorbent polymer may be
uniformly dispersed in the other fibers, or the various fibers may
be adhered to substrate in patterns.
[0028] Regardless of type, the length of the flocked fibers should
be less than about 1 mm, preferably less than about 0.8 mm. The
denier of the flocked fibers should be in the range of about 1.2d
to about 15d, preferably about 1.8d to about 6d. It is also
preferred that the fibers suffer little or no wet collapse.
[0029] The flocked fibers may be adhered to all or a portion of the
substrate. The flocked fibers may be on one or all sides of the
substrate. The same or different flocked fibers may be on two or
more different areas of the substrate.
[0030] In another embodiment of the invention, the substrate is an
apertured film. The apertured film comprises a top surface, an
underside surface, and a plurality of apertures. The apertures
originate in the top surface and extend through the underside
surface of the film. Each of the apertures is defined by a sidewall
having an inner surface and an outer surface. The geometry and size
of the apertures are not critical to the invention, and a variety
of apertured films are known in the art, any of which may be used
in the present invention. See for example, U.S. Pat. Nos. 5,824,352
and 5,770,144 and the references cited therein.
[0031] The flocked fibers of superabsorbent polymer may be located
on the top surface of the apertured film, or the underside surface
of the apertured film. Preferably, the flocked fibers are adhered
to the underside surface of the apertured film. In addition, the
flocked fibers are preferably adhered to the outer surfaces of the
aperture sidewalls. The latter advantageously creates tendrils of
superabsorbent polymer extending from the end of the aperture
sidewalls. These tendrils aid in pulling fluid through the
apertures and away from the top surface of the film.
[0032] The method of aperturing the film is also not critical to
the invention. In general, known methods involve supporting a
starting film on the surface of a topographical support member
having a pattern of holes and/or other features on its surface.
Fluid such as water is directed against the starting film to
rupture it and conform its shape to that of the support member's
surface. Alternatively, the starting film may be apertured and
conformed by drawing a vacuum underneath the starting film. See for
example, U.S. Pat. Nos. 5,824,352 and 5,770,144.
[0033] The flocking step may take place before or after the film
aperturing step. Preferably, flocking is done after aperturing.
When applying the adhesive onto an apertured film, care must be
taken to apply adhesive only to the land areas of the film.
[0034] FIGS. 1 and 2 are magnified views of the top and underside
surfaces, respectively, of an apertured film comprising flocked
fibers of superabsorbent polymer OASIS Type 101, rayon, and
polyester on its underside surface according to the invention. The
top surface 1, underside surface 2, and apertures 3 are shown.
Flocked fibers 4 are adhered to the underside surface 3 of the
film. Note that many of the flocked fibers extend or blossom into
the open area of the apertures from the surrounding land area of
the film.
[0035] Such an apertured film may be used, for example, as either
the cover or the backsheet of an absorbent article. Preferably, it
is used as the cover of an absorbent article, since a perforated
backsheet may leak fluid onto the user's undergarment.
[0036] FIG. 3 depicts a pantiliner comprising a cover made of an
apertured film having flocked fibers of superabsorbent polymer
thereon according to the invention. The pantiliner shown in FIG. 3
comprises in sequence from its body-facing surface 1 to its
garment-facing surface 2 the cover 3, an absorbent core 4, and a
liquid impermeable backsheet 5. The thickness of the cover may vary
from approximately 0.001 to 0.062 inch, depending on the material
chosen. Generally, cover 3 is a single sheet of material having a
width sufficient to form the body-facing surface 1 of the article.
The cover may be longer than the absorbent core so as to form
transverse ends. The transverse ends may be sealed with other
layers to fully enclose the absorbent core.
[0037] The absorbent core 4 may be comprised of a loosely
associated absorbent hydrophilic material such as cellulose fibers,
including wood pulp, regenerated cellulose fibers or cotton fibers,
or other absorbent materials generally known in the art, including
acrylic fibers, polyvinyl alcohol fibers, peat moss and
superabsorbent polymers.
[0038] The absorbent article further comprises a liquid impermeable
backsheet 5, the exterior of which forms the garment-facing surface
of the article. The thickness of the backsheet when formed from a
polymeric film typically is about 0.001 to 0.002 inch. A variety of
materials are known in the art for use as backsheet, and any of
these may be used. Generally, the backsheet 5 is a single sheet of
material having a width sufficient to form the garment-facing
surface 2 of the absorbent article. The backsheet may extend around
the sides of the absorbent core in a C-shaped configuration with
the portions of the backsheet adjacent its longitudinal edges
extending upwardly from the garment-facing surface toward the
body-facing surface of the article. Preferably the backsheet is
made of a breathable material.
[0039] The absorbent article may be applied to the crotch of
underpants by placing the garment-facing surface 2 of the absorbent
article against the inside surface of the crotch of the underpants.
Strips of pressure sensitive adhesive 6 may be applied to the
garment-facing surface 2 of the absorbent article to help maintain
it in place. As used herein, the term "pressure-sensitive adhesive"
refers to any releasable adhesive or releasable tenacious means.
Suitable pressure sensitive adhesives include for example
water-based adhesives such as acrylate adhesives. Alternatively,
the adhesive may comprise rapid setting thermoplastic "hot melt"
rubber adhesives or two-sided adhesive tape.
[0040] A paper release strip 7 that has been coated on one side may
be applied to protect the strips of adhesive 6 prior to use. The
coating, for example silicone, reduces adherence of the coated side
of the release strip to the adhesive. The release strip can be
formed from any suitable sheet-like material which, when coated,
adheres with sufficient tenacity to the adhesive to remain in place
prior to use but can be readily removed when the absorbent article
is to be used.
[0041] The absorbent article may comprise other known materials,
layers, and additives, such as transfer layers, foam layers, odor
control agents, medicaments, and the like, many examples of which
are known in the art. A transfer layer in particular, however, may
advantageously be unnecessary in the present absorbent article, as
further explained below. The absorbent article can optionally be
embossed with decorative designs using conventional techniques.
[0042] The following non-limiting examples further illustrate the
invention.
EXAMPLE 1
[0043] An absorbent core comprising flocked fibers of
superabsorbent polymer was prepared as follows.
[0044] A one ounce per square yard substrate of 100% polyester was
used as the carrier fabric. A polymerizable resin was applied in
various patterns to the polyester fabric. A fiber blend consisting
of 30 percent superabsorbent fibers, 40 percent rayon fibers, and
30 percent polyester fibers was metered on the polyester fabric.
The fibers were oriented in the vertical position via an
electrostatic field. The fibers adhered where the resin was
applied. The substrate was then passed through an oven to
polymerize the resin, anchoring the fibers to the polyester fabric.
The excess fibers were vacuumed away.
EXAMPLE 2
[0045] An apertured film comprising flocked fibers of
superabsorbent polymer is prepared as follows.
[0046] A starting film of polyethylene is placed over a
topographical support member having a pattern of holes thereon. The
support member is rotatably mounted on a drum. Water at a
temperature of about 160.degree. F. and a pressure of about 1350
psig is directed against the surface of the starting film opposite
to the surface contacting the support member, thereby aperturing
the starting film.
[0047] The film is dried. Flocked fibers comprising a blend of 30
percent superabsorbent fibers, 40 percent rayon fibers, and 30
percent polyester fibers is metered onto the apertured film. The
fibers are oriented in the vertical position via an electrostatic
field. The fibers adhere where the resin is applied. The substrate
is then passed through an oven to polymerize the resin, anchoring
the fibers to the polyethylene film. The excess fibers are vacuumed
away.
* * * * *