Note: Descriptions are shown in the official language in which they were submitted.
FLEXIBLE DISPOSABLE SHEET WITH ABSORBENT CORE
BACKGROUND
[0001] Bed sores, also known as pressure ulcers or decubitus ulcers, are
prevalent
among people who are bed-ridden or otherwise immobilized. Skin ulcers can be
caused by
pressure exerted on the skin and soft tissues (e.g., the individual's body
weight resting against
a hard surface such as a bed or chair) and are exacerbated when the skin is
also exposed to
moisture (e.g., due to incontinence) and/or friction, heat, and shear forces,
for example caused
by moving or repositioning a bed-ridden patient.
[0002]
Elderly nursing home residents are particularly vulnerable to pressure ulcers
since they are frequently bed-ridden and incontinent. Approximately one out of
ten nursing
home residents have some form of pressure ulcers. Since pressure ulcers can be
persistent and
heal slowly, treating pressure ulcers once formed is thus expensive, so there
is a significant
need to minimize a patient's exposure to conditions which would cause such
ulcers.
[0003]
For example, it would be beneficial for bed-ridden persons who are incontinent
or have other moisture management issues to lay on a pad or layer which would
not only
absorb moisture but also maintain skin dryness. It would also be useful to
protect the bed and
linens from moisture as well in order to maintain hygiene and minimize the
need for hospital
staff to change bed linens. Additionally, in order to minimize heat buildup
between the
bedding and the patient's skin, and to maintain skin health, it would be
beneficial for the
absorbent pad or layer to allow air circulation between the pad and the skin.
Furthermore,
since bed-ridden patients need to be lifted and repositioned, for example to
change bed linens,
for medical procedures, or to prevent the formation of pressure ulcers, it
would be useful for
the absorbent pad to have sufficient strength to allow such repositioning.
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[0004]
Current products do not provide a solution to all four needs: 1) maintaining
skin dryness 2) protecting the bed and linens, 3) allowing air circulation,
and 4) allowing
caregivers to reposition the individual. Typically a caregiver will combine up
to eight
disposable underpads to absorb moisture, as well as reusable cloth underpads
or sheets to
.. protect the bed and linens and to lift and reposition the patient.
[0005]
Combinations of multiple absorbent products are less than ideal for several
reasons. From a strictly practical standpoint, using multiple absorbent
products is more
expensive, and requires more packaging, storage, shipping costs, waste, and
the like. Reusable
cloth underpads, or drawsheets, are also the second most expensive item for
hospitals to
launder and process. Moreover, the combination of multiple products is not
very effective in
preventing damage to the skin, while at the same time protecting bedding.
Multiple layers of
absorbent pads can increase the shear and friction experienced by individuals
as the layers
slide and shift against each other. Furthermore, conventional disposable pads
disintegrate
when wet, and reusable cloth underpads prevent air circulation. Furthermore,
the thickness
.. of the multiple layers can interfere with 'pressure management beds and
surfaces which
distribute weight to minimize or prevent excessive pressure.
[0006]
There is therefore a need for an absorbent pad which maintains skin dryness
by absorbing moisture while preventing leakage to the skin or the bed linens,
allowing air
circulation at the surface of the patient's skin to prevent heat buildup, and
which is strong
enough to allow the patient to be repositioned, even when the pad is wet.
SUMMARY OF THE INVENTION
[0007]
According to an aspect of the present invention, there is provided a sheet
adapted for covering a patient support structure comprising:
a first layer having a first length and a first width and comprising a
flexible, fluid
permeable, air permeable material;
a second layer having the first length and the first width and being disposed
under the
first layer, the second layer comprising at least one super absorbent
material;
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a base layer disposed adjacent to the second layer, the base layer having a
second width that
is greater than the first width such that a portion of the base layer extends
beyond the first and
second layers on opposing sides of the sheet and having a second length that
is greater than
the first length, the base layer comprising:
a third layer comprising a hydrophobic breathable film;
a fourth layer comprising an air permeable material;
a handle comprising a void formed in the portion of the base layer that
extends beyond
the first and second layers; and
an elastic cord joined to and extending along at least a portion of the
perimeter of the
base layer,
wherein a tensile strength of the base layer at break, when measured by an
ASTM 882
method, is in a range of 45 to 100 N/25 mm in a machine direction and 30 to 60
N/25 mm in
a cross direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Figure 1. Cross-section of an embodiment of the absorbent
pad of the
present invention.
[0009] Figure 2. Maximum Lift Weight testing device.
[0010] Figure 3. Cross-section of an embodiment of the absorbent
pad of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0011] In various embodiments, the present invention is directed
towards an absorbent
pad comprising multiple layers, e.g., three or more layers, wherein the first
layer is comprised
of a fluid-permeable, porous material, the second layer is disposed under the
first layer and is
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Date Recue/Date Received 2021-01-06
comprised of at least one super absorbent material, and a base layer disposed
under the second
layer. Additionally, the base layer has a tensile strength at break, when
measured by the ASTM
D 882 method, in the range of about 45 N/25 mm to 100 N/25 mm in the machine
direction and
about 30 to 60 N/25 mm in the cross direction.
[0012] In certain embodiments of the invention, the base later is comprised
of a third
layer comprised of a hydrophobic, breathable film, disposed under the second
layer and a fourth
layer, disposed under the third layer, comprised of an air-permeable material.
[0013]
In one embodiment of the invention, the first layer is a nonwoven material.
The
nonwoven material of the first layer can be manufactured using any technique
known in the art.
Non-limiting examples of suitable types of nonwoven materials include staple
nonwoven
materials, melt-blown nonwoven materials, spunmelt nonwoven materials,
spunbond nonwoven
materials, SMS (spunbond meltblown spunbond) materials, spun lace materials,
needle-felted
materials, thermal-bonded nonwoven materials, trough-air-bonded nonwoven
material, spunlaid
nonwoven material, air-laid nonwoven materials or the like, or any
combinations thereof
[0014] In certain embodiments of the invention the first layer is
hydrophilic For example,
the first layer can be treated in order make it fluid permeable. Such
treatments can include any
treatment known in the art which renders a material fluid permeable. Non-
limiting examples of
such treatments include: coating the surface of the material with a
hydrophilic surfactant as
described in WO 93/04113 entitled "Method for hydrophilizing absorbent foam
materials" and
in WO 95/25495 entitled "Fluid acquisition and distribution member for
absorbent core"; surface
treatments such as corona and plasma treatment as described m described in
U.S. Pat. No.
6,118,218 entitled "Steady-state glowdischarge plasma at atmospheric
pressure"; applying a
hydrophilic coating by a plasma polymerization process as described in WO
00/16913 entitled
"Durably wettable, liquid pervious webs" and WO 00/16914 entitled "Durably
wettable, liquid
.. pervious webs prepared using a remote plasma polymerization process"; or
contacting the fibers
with a solution of hydrophilic monomers and radical polymerization initiators
and exposing the
fibers to UV radiation as described in U.S. Pat. No. 7,521,587 entitled
"Absorbent articles
comprising hydrophilic nonwoven fabrics".
[0015]
In another embodiment of the invention, the first layer is permeable to fluids
such
that the fluids can pass through the surface of the first layer toward the
second layer (disposed
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Date Recue/Date Received 2020-06-26
beneath the first layer), but the fluids cannot substantially reverse
direction and move back toward
the surface of the first layer. In other words, in various embodiments the
flow of fluids through
the first layer is substantially unidirectional from the top surface of the
first layer toward the second
layer disposed beneath the first layer.
[0016] The first layer can comprise any suitable material known in the art.
For example,
the first layer can comprise a polymeric material. Non limiting examples of
such polymeric
materials include polypropylene, polyethylene, polyethylene terephthalate,
polyamide, viscose
rayon, nylon, or the like or any combinations thereof. Furthermore, the
polymeric material can be
a biodegradable polymeric material. One such non-limiting example of a polymer
is the starch-
based biodegradable material described in United States Patent Application
2009/0075346. In
certain embodiments of the invention, the first layer has a weight per unit
area (weight) in the
range of about 15 gsm (grams per square meter) to about 20 gsm. For example,
the first layer can
have a weight of about 15 gsm, about 16 gsm, about 17 gsm, about 18 gsm, about
19 gsm, or
about 20 gsm, inclusive of all ranges and subranges therebetween.
[0017] In certain embodiments of the invention, the first layer is fluid
permeable. In one
embodiment of the invention the first layer has a Moisture Transfer Rate, for
example as
measured by ASTM E96M - 05 in the range of about 5 to about 200 sec/mL.
[0018] In another embodiment of the invention, the first layer is air
permeable. In certain
embodiments, the first layer has an air permeability of the range of about 10
seconds/100 mL to
about 100 seconds/100 mL, including about 10 seconds/100 mL, about 20
seconds/100 mL, about
seconds/100 mL, about 40 seconds/100 mL, about 50 seconds/100 mL, about 60
seconds/100
mL, about 70 seconds/100 mL, about 80 seconds/100 mL, about 90 seconds/100 mL,
or about 100
seconds/100 mL, inclusive of all ranges and subranges therebetween, for
example as measured by
the Gurely method using a densometer, (e.g., methods conforming the following
standards: ASTM
25 0737 and WSP 70.1).
[0019] The second layer of the absorbent pad of the present invention
is disposed beneath
the first layer, as described herein. For example, the second layer can be
located directly beneath
the first layer and in direct contact with the first layer, or adhered to the
first layer by means of one
or more intervening layers, for example an adhesive layer and/or a spacer
layer.
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[0020] In certain embodiments the second layer is comprised of a
formed material. The
formed material of the second layer can be manufactured using any technique
known in the art.
Non-limiting examples of suitable types of formed materials include staple
nonwoven materials,
melt-blown nonwoven materials, spun-melt nonwoven materials, spun-bound
nonwoven
materials, thermal-bonded nonwoven materials, trough-air-bonded nonwoven
materials, spun-
laid nonwoven materials, air-laid nonwoven materials, or any combinations
thereof. In a
particular embodiment the second layer is comprised of an air-laid fiber. In
one embodiment the
air-laid fiber is thermobonded. In a particular embodiment the air-laid
material is air laid paper.
[0021] The second layer can comprise fibers, for example natural
fibers. The natural
fibers can be any suitable natural fibers known in the art. In one embodiment
the natural fiber is
cellulose. The cellulose can be from any suitable source known in the art. Non-
limiting
examples of suitable sources of cellulose are wood fibers, plant fibers, field
crop fibers, fluff
pulp fibers, cotton, any other material, man-made or natural, designed to
absorb fluid, or any
combination thereof. In a particular embodiment the second layer comprises
wood fibers. In
another embodiment, the second layer comprises macerated wood pulp.
[0022] The second layer of the pad can further comprise an absorbent
polymer, for
example any super-absorbent polymer known in the art. Non-limiting examples of
suitable
super-absorbent polymers include, for example, polymers and copolymers of
acrylic acid and
salts thereof (including alkali metal salts such as sodium salts, or alkaline
earth salts thereof),
polymers and copolymers of methacrylic acid and salts thereof (including
alkali metal salts such
as sodium salts, or alkaline earth salts thereof), polyactylamide polymers and
copolymers,
ethylene maleic anhydride copolymers, cross-linked carboxy-methyl-celluloses,
polyacrylate/polyacrylamide copolymers, polyvinyl alcohol copolymers, cross-
linked
polyethylene oxides, starch grafted copolymers of polyacrylonitrile, etc. The
super-absorbent
polymers can be cross-linked to suitable degree.
[0023] In a particular embodiment the super-absorbent polymer
comprises sodium
polyacrylatc. In another embodiment, the second layer comprises an amount of
super-absorbent
polymer(s) in the range of about 15 gsm to about 35 gsm. For example, the
super-absorbent
polymer(s) in the second layer is present in an amount of about 15 gsm, about
20 gsm, about 25
gsm, about 30 gsm, or about 35 gsm, inclusive of all ranges and subranges
therebetween.
5
[0024]
In another embodiment, the cellulose fibers of the second layer are present in
the
second layer in an amount of about 85 gsm to about 115 gsm. For example, the
cellulose fibers of
the second layer are present in an amount of about 85 gsm, about 90 gsm, about
95 gsm, about
100 gsm, about 103 gsm, about 105 gsm, about 110 gsm, about 115 gsm, or about
120 gsm,
inclusive of all ranges and subranges therebetween.
[0025]
In a particular embodiment, the second layer is a thermobonded, absorbent
airlaid
core made from cellulose fibers and super-absorbent polymers. In a particular
embodiment of the
invention, the second layer is comprised of an airlaid absorbent core as
described in U.S. Patent
No. 6,675,702. In yet another embodiment, the second layer is comprised of a
thermobonded
airlaid core made from about 100 to about 105 gsm of cellulose fibers and 25
gsm of super
absorbent polymers. In a particular embodiment, the cellulose fibers are
macerated wood pulp.
[0026]
The second layer absorbs substantially all of the fluids penetrating through
from
the first layer, and has a fluid-holding capacity sufficient to retain fluids
without releasing the fluid
through the first layer or through the third and fourth layers. In certain
embodiments, the second
layer has an absorption capacity in the range of about 50 cc/m2 to about
20,000 cc/m2, for
example, about 50 cc/m2, about 100 cc/m2, about 150 cc/m2, about 200 cc/m2,
about 250 cc/m2,
about 300 cc/m2, about 350 cc/m2, about 400 cc/m2, about 450 cc/m2, about 500
cc/m2, about
550 cc/m2, about 600 cc/m2, about 650 cc/m2, about 700 cc/m2, about 750 cc/m2,
about 800
cc/m2, about 850 cc/m2, about 900 cc/m2, about 1,000 cc/m2, about 1, 100
cc/m2, about 1,200
cc/m2, about 1,300 cc/m2, about 1,400 cc/m2, about 1,500 cc/m2, about 1,600
cc/m2, about
1,700 cc/m2, about 1,800 cc/m2, about 1,900 cc/m2, about 2,000 cc/m2, about
3,000 cc/m2, about
4,000 cc/m2, about 5,000 cc/m2, about 6,000 cc/m2, about 7,000 cc/m2, about
8,000 cc/m2, about
9,000 cc/m2, about 10,000 cc/m2, about 11,000 cc/m2, about 12,000 cc/m2, about
13,000 cc/m2,
about 14,000 cc/m2, about, 15,000 cc/m2, about 16,000 cc/m2, about 17,000
cc/m2, about, 18,000
cc/m2, about 19,000 cc/m2, or about 20,000 cc/m2 inclusive all ranges and
subranges
therebetween, as measured by the ISO 11948-1 test method.
[0027]
In a particular embodiment of the present invention, the second layer can be
comprised of more than one fluid absorbing layer (also known as "core"
layers). For example, the
second layer can comprise two (or more) layers, each comprising the same or
different absorbent
polymer.
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[0028] In order to minimize or prevent the formation of ulcers in a
patient using the
absorbent pad of the present invention, the pad should remain as uniform in
thickness as
possible, even after absorbing fluids from the patient. Accordingly, the pad
should not swell
substantially, nor should the various layers in contact with the absorbent
(second) layer separate
within the pad. Applicants have found that air laid materials comprising a
combination of a
cellulosic material and a superabsorbent polymer, as described herein do not
substantially swell
or separate from the other layers (e.g., the first and/or third layers) when
wetted with fluids from
the patient. By "not swell substantially" we mean that the absorbent second
layer does not
increase in thickness more than about 200%, for example less than about 200%,
less than about
190%, less than about 180%, less than about 170%, less than about 160%, less
than about 150%,
less than about 140%, less than about 130%, less than about 120%, less than
about 110%, less
than about 100%, less than about 90%, less than about 80%, less than about
70%, less than about
60%, less than about 50%, less than about 40%, less than about 30%, less than
about 20%_ or
less than about 10% in thickness, inclusive of all ranges and subranges
therebetween. By "not
substantially separate", we mean that at least about 60%, for example less
than about 60%, less
than about 50%, less than about 40%, less than about 30%, less than about 20%,
or less than
about 10%, of the surface area of the absorbent second layer remains adhered
to or in direct
contact with the first and third layers of the absorbent pad (or remains
adhered to or in direct
contact with an adhesive and/or spacer layer disposed between the first and/or
third layers and
the absorbent second layer).
[0029] The base layer prevents fluid absorbed in the second layer from
going through the
bottom of the absorbent pad. The base layer should also provide for air
circulation within the
absorbent pad to prevent heat and moisture vapor build up.
[0030] In certain embodiments of the invention, the base layer is
comprised of a third and
fourth layer, wherein the third layer is disposed under the second layer and
the fourth layer
disposed under the third layer.
[0031] The base layer (or in certain embodiments, the third layer)
prevents the fluid
absorbed in the second layer to penetrate through the base layer of the
absorbent pad (or in some
embodiments, the fourth layer). The base layer can comprise any natural or man-
made material
capable of preventing the flow of fluids out of the second layer and through
the bottom of the
absorbent pad. In certain embodiments wherein the base layer comprises a third
and fourth
7
layer, the third layer comprises a polymeric film, for example a hydrophobic
polymeric film. The
polymeric film of the third layer can be any suitable polymer known in the
art, for example suitable
hydrophobic polymers. Non-limiting examples of such polymers include
polyolefins such as
polyethylene, polypropylene, poly(lactic acid), polyhydroxybutyrate, and
tapioca starch as well as
copolymers thereof One such non-limiting example of a polymer is the starch-
based
biodegradable material described in United States Patent Application
2009/0075346.
[0032] The base layer should also provide for air circulation within
the absorbent pad to
prevent heat and moisture vapor build up. Accordingly, in particular
embodiments, the base layer
is air permeable. Air permeability can be provided in various ways, for
example by forming a base
.. layer comprising a third and fourth, wherein the third layer comprises a
woven or nonwoven
hydrophobic material which prevents the movement of bulk fluid, but allows
diffusion or
movement of air through the third layer. For example, the hydrophobic material
can comprise
hydrophobic polymeric fibers (e.g., polyolefin fibers) or comprising fibers
surface treated with a
hydrophobic sizing orcoating. In yet another embodiment the third layer
comprises a perforated
polyolefin (e.g polyethylene and/or polypropylene polymer or copolymer) sheet
If the third layer
comprises a perforated polyolefin sheet, the perforations should be of a size
which does not permit
the permeation or movement of liquids through the perforations, but does
provide air permeability
values within the ranges described herein.
[0033] Although the base layer does not permit any appreciable amount
of liquid to flow
through, in many instances it can be advantageous to allow moisture vapor to
permeate through
the base layer. In certain embodiments of the invention, for a base layer
comprising a third and
fourth layer, the third layer has a moisture vapor transmission rate (MTVR) in
the range of about
1,000 g/m2/day to about 10,000 g/m2/day. For example, the third layer can have
an MTVR of
about 1,000 g/m2/day, about 2,000 g/m2/day, about 3,000 g/m2/day, about 4,000
g/m2/day, about
5,000 g/m2/day, about 6,000 g/m2/day, about 7,000 g/m2/day, about 8,000
g/m2/day, about 9,000
g/m2/day, or about 10,000 g/m2/day, inclusive of all ranges and subranges
therebetween.
[0034] In yet another embodiment of the invention, the third layer
has a moisture vapor
transmission rate (MTVR) in the range of about 2,500 g/m2/day to about 4,500
g/m2/day. For
example, the third layer can have an MTVR of about 2,500 g/m2/day, about 2,600
g/m2/day,
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Date Recue/Date Received 2020-06-26
about 2,700 g/m2/day, about 2,800 g/m2/day, about 2,900 g/m2/day, about 3,000
g/m2/day, about
3,100 g/m2/day, about 3,200 g/m2/day, about 3,300 g/m2/day, about 3,400
g/m2/day, about 3,500
g/m2/day, about 3,600 g/m2/day, about 3,700 g/m2/day, about 3,800 g/m2/day,
about 3,900
g/m2/day, about 4,000 g/m2/day, about 4,100 g/m2/day, about 4,200 g/m2/day,
about 4,300
.. g/m2/day, about 4,400 g/m2/day or about 4,500 g/m2/day, inclusive of all
ranges and subranges
therebetween.
[0035]
In various embodiments of the present invention wherein the base layer
comprises
a third and fourth layer, the third layer has a weight in the range of about
20 gsm to about 45 gsm.
For example, the third layer can have a weight of about 20 gsm, 25 gsm, 30
gsm, 35 gsm, 40 gsm,
or 45 gsm inclusive of all ranges and subranges therebetween.
[0036]
In one embodiment of the invention, the fourth layer is a non-woven material.
The
non-woven material of the fourth layer can be manufactured using any technique
known in the
art. Non-limiting examples of suitable types of nonwoven materials include
staple nonwoven
materials, melt-blown nonwoven materials, spunmelt nonwoven materials,
spunbond nonwoven
materials, SMS (spunbond meltblown spunbond) materials, spun lace materials,
needle-felted
materials, thermal-bonded nonwoven materials, trough-air-bonded nonwoven
material, spunlaid
nonwoven material, air-laid nonwoven materials or the like, or any
combinations thereof
[0037]
In certain embodiments of the invention the fourth layer is hydrophobic. The
fourth
layer can be made of any suitable material known in the art. Non limiting
examples of such
materials include polypropylene, polyethylene, polyethylene terephthalate,
polyamide, viscose
rayon, nylon, or any combinations thereof or the like. Furthermore, the
polymeric material can
be a biodegradable polymeric material. One such non-limiting example of a
polymer is the starch-
based biodegradable material described in United States Patent Application
2009/0075346. In
certain embodiments of the invention, the fourth layer has a weight in the
range of about 30 to
about 80 gsm. For example, the fourth layer can have a weight of about 30 gsm,
about 35 gsm,
about 40 gsm, about 45 gsm, about 50 gsm, about 55 gsm, about 60 gsm, about 65
gsm, about 70
gsm, about 75 gsm or about 80 gsm and all sub-ranges between. In another
embodiment, the
fourth layer has a weight of about 15 gsm to about 90 gsm. In another
embodiment, the fourth
layer has a weight of about 30 gsm to about 90 gsm.
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[0038] Any embodiments of the first layer described herein can be
independently
combined with any particular embodiments of the second, third, and fourth
layers described
herein. For example, in a particular embodiment the first layer is a spunbond,
nonwoven sheet;
the second layer comprises cellulose fibers and super absorbent polymers; the
third layer is a
perforated polyethylene film and the fourth layer is a nonwoven sheet.
[0039] In a certain embodiments, the first layer is a spunbond,
nonwoven sheet with a
weight of about 10-20 grams; the second layer comprises cellulose fibers and
super absorbent
polymers; the third layer is a perforated polyethylene film with a weight of
about 30 grams and
the fourth layer is a nonwoven sheet with a weight of about 40 to 60 gsm.
[0040] In other embodiments, the first layer is a hydrophilic. SMS
polyethylene
nonwoven sheet with a weight of about 10 to about 20 gsm; the second layer is
a thermobonded
absorbent airlaid core comprising about 103 gsm wood pulp fibers and about 25
gsm super
absorbent polymers; the third layer is a perforated polyethylene film with a
weight of about 20
gsm, and the fourth layer is a nonwoven, BTBS film with a weight of about 50
gsm. See Figure
1.
[0041] In yet other embodiments, the absorbent pad has handles. In a
particular
embodiment, the handles are formed by extending the dimensions of the base
layer beyond the
other two layers and forming voids in the backing material. The voids can be
formed for fingers
or hands. In another embodiment, a suitable material of a suitable size can be
adhered to the
edge of the absorbent pad to form handles.
[0042] In various embodiments, the first, second, and base layers are
adhered together.
The layers can be adhered together using any suitable technique known in the
art. In a particular
embodiment, the layers are adhered together using an adhesive. Any suitable
adhesive known in
the art can be used. The adhesive used can be natural or synthetic. Non-
limiting examples of
such adhesives are hot melt adhesives, drying adhesives, contact adhesives, UV
curing
adhesives, light curing adhesives, and pressure sensitive adhesives or the
like. In one
embodiment, the top layer and the edges where the layers meet are glued
together using hot melt
adhesive.
[0043] In various other embodiments, the pad comprises first, second,
third, and fourth
layers as described herein, adhered together. The layers can be adhered
together using any
suitable technique known in the art. In a particular embodiment, the layers
are adhered together
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using an adhesive. Any suitable adhesive known in the art can be used. The
adhesive used can
be natural or synthetic. Non-limiting examples of such adhesives are hot melt
adhesives, drying
adhesives, contact adhesives, UV curing adhesives, light curing adhesives, and
pressure sensitive
adhesives or the like. In one embodiment, the top layer and the edges where
the layers meet are
glued together using hot melt adhesive.
[0044] Non-limiting examples of adhesives include animal glue,
collagen-based glue,
albumin glue, casein glue, Canada balsam, coccoina, pelikanol, gum Arabic,
latex, methyl
cellulose, library glue, mucilage, resorcinol resin, starch, urea-formaldehyde
resin, acrylonitrile,
cyanoacrylate, acrylic, epoxy resins, epoxy putty, ethylene-vinyl acetate,
phenol formaldehyde
resin, polyamide, polyester resins, polyethylene, polypropylene, polysulfides,
polyurethane,
polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride, polyvinyl chloride
emulsion,
polyvinylpyrrolidone, rubber cement, silicones, styrene acrylic copolymer,
ethylene-acrylate
copolymers, polyolefins, atactic polypropylene, polybutene-1, oxidized
polyethylene, styrene
block copolymers, polycarbonates, fluoropolymers, silicone rubbers, or the
like and various other
.. co-polymers. The adhesive may further comprise one or more additives. Any
suitable additive
known in the art can be used. Non-limiting examples of additives include,
tackifying resins,
waxes, plasticizers, antioxidants, stabilizers, UV stabilizers, pigments,
dyes, biocides, flame
retardants, antistatic agents, and fillers or the like. In particular
embodiments, the adhesive
comprises a hot-melt adhesive.
[0045] The adhesive layer(s) can be continuous, contacting substantially
the entire
surface area of any two layers adhered together (e.g. at least about 75%, at
least about 80%, at
least about 85%, at least about 90%, at least about 90%, or essentially about
100% of the surface
area of the two layers adhered together, inclusive of all ranges and subranges
therebetween).
That is, the adhesive forms an intermediate layer between any two layers
adhered together,
contacting substantially the entire surfaces between the two layers.
Alternatively, the adhesive
can be applied in a pattern (e.g., grid) or random fashion whereby the
adhesive does not
substantially contact the entire surface area of the two layers, but rather
forms a discontinuous
intermediate layer between the two adhered surfaces. Each of the first,
second, and base layers
(or first, second, third, and fourth layers when present) of the absorbent pad
of the present
.. invention can be adhered together with continuous adhesive layers, or with
discontinuous
adhesive layers, or some of the adhesive layers can be continuous adhesive
layers, and other
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adhesive layers can be discontinuous layers. Each of the adhesive layers can
comprise the same
adhesive material (as described herein), or one or more of the adhesive layers
can comprise a
different adhesive material (as described herein).
[0046] The present invention can be assembled from the component
layers by any
suitable method known in the art. In one embodiment of the invention, rolls of
each layer are
combined such that the first layer is disposed over the second, which is
disposed over the base
(or in some embodiments, third, which is disposed over the fourth), and the
combined layers are
then cut to the appropriate size and the edges adhered together. In another
embodiment of the
invention, sheets of a suitable size are cut from rolls of each individual
layer, then combined in
the appropriate order and the edges are adhered together. In yet another
embodiment of the
invention, the dimension of the base layer exceeds that of the second layer in
either width, length
or both by 1 inch to 5 inches. The second layer can be disposed over the base
layer such that the
base layer extends about 0.5 to about 2.5 inches beyond the second layer on
either opposing sides
or all sides, and the material of the base layer which extends beyond the
second layer can be
folded over and adhered to the second layer by any known means in the art. A
first layer of the
same dimensions as the second layer can be disposed over and adhered to the
second layer.
[0047] In a further embodiment of the invention, the dimensions of the
fourth layer and
the third layer exceeds that of the second layer in either width, length or
both by 1 inch to 5
inches. The third layer is disposed over the fourth layer, and the second
layer can be disposed
over the third such that the third and fourth layers extend about 0.5 to about
2.5 inches beyond
the second layer on either opposing sides or all sides. The material of the
third and fourth which
extends beyond the second layer can be folded over and adhered to the second
layer by any
known means in the art. A first layer of the same dimensions as the second
layer can be disposed
over and adhered to the second layer.
[0048] The pads of the present invention can be of any suitable size. In
one embodiment
of the invention, the pads are about 36" by about 31". In one embodiment of
the invention, the
pads are about 36" by about 30". In yet another embodiment of the invention,
the pads are about
36" by about 24". In certain embodiment, the pads are about 36" by about 23".
In another
embodiment the pads are about 30" by 30". In yet another embodiment, the pads
are about 24"
by about 18". In a further embodiment, the pads are about 24" to about 17".
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[0049] In further embodiments, a pad of the present invention may be
integrated with a
sheet with fitted corners, sized to fit an operating room table, stretcher,
bed or other patient
support structure. The sheet may comprise a resilient material such as an
elastic cord, string or
tape that is connected to an edge of the flexible sheet material in such a way
that it gathers the
flexible material into a fitted end or comer that would allow the user to tuck
the corners of the
sheet around a mattress pad or other support structure in order to secure the
sheet and pad against
movement relative to the support surface.
[0050] In one embodiment of the invention, the pad extends across
substantially the
entire area of the sheet, the pad providing the flexible material for forming
the fitted corners. In
an alternative embodiment, the sheet may be formed by extending the first
layer or topsheet,
described above and shown in FIG. 1, beyond the perimeter of the other layers
of the pad such
that the extended portion of the topsheet provides the flexible material that
is used to form the
fitted corners. In another embodiment, the sheet may be formed by extending
the fourth layer or
backsheet, described above and shown in FIG. 1, beyond the perimeter of the
other layers of the
pad such that the extended portion of the backsheet provides the flexible
material that is used to
form the fitted comers. In a further embodiment, the pad may be joined to a
section of additional
material that surrounds one or more edge of the pad in order to provide the
flexible material used
to form the fitted corners. This additional material may be any appropriate
flexible material and
may be fluid-permeable or non-fluid-permeable. In yet another embodiment, the
sheet may be
formed by providing a flexible sheet having fitted corners and securing a pad,
as described
herein, to an upper or lower surface of the flexible sheet. The pad may be
secured to the sheet by
adhesive, thermal or ultrasonic bonding, mechanical engagement or by any other
appropriate
means to connect the pad with the sheet as would be apparent to one of
ordinary skill in the art.
[0051] In one embodiment of the invention, the pad may be sized such
that it covers
substantially the entire upper surface of the patient support structure. In
other embodiments, the
pad may be smaller in area than the upper surface of the support structure. In
certain
embodiments, the pad may be located within the sheet such that the pad is
positioned on an area
of the support structure more likely to be wetted with fluids.
[0052] In a certain embodiment, the absorbent pad of the present
invention has a Total
Absorption Capacity, as measured by ISO Standard 11948-1, from about 4,000
g/m2 to about
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4,500 gm2, for example about 4,000 g/m2, about 4,100 g/m2, about 4,200 g/m2,
about 4,300
g/m2, about 4,400 g/m2 or about 4,500 g/m2.
[0053] The rate of acquisition and rewet properties of the pad of the
present invention
can be determined by any suitable method, for example the Medi-Cal method. The
Medi-Cal
acquisition rate and rewet test protocols comprise laying the pad of the
present invention (as
described herein) on a flat surface, then rapidly adding 100 or 200 mL of a
0.09% saline solution
onto the center of the pad (the target area). The time required for the saline
solution to pass
through the top sheet of the pad is the rate of acquisition. Approximately 12
minutes after
adding the saline solution to the pad, a preweighed (-10 g) stack of dry
filter paper is placed on
the center of the target area, and weighted with a 1.0 psi weight. After 1
minute, the filter paper
stack is removed and weighed. The weight of moisture absorbed by the filter
paper stack is the
rewet value.
[0054] Suitable rewet values determined by the Medi-Cal method fall
within the range of
about 1 g to about 3 g, e.g., about 1 g, about 1.1 g, about 1.2 g, about 1.3
g, about 1.4 g, about 1.5
g, about 1.6 g, about 1.7 g, about 1.8 g, about 1.9 g, about 2.0 g, about 2.1
g, about 2.2 g, about
2.3 g, about 2.4 g, about 2.5 g, about 2.6 g, about 2.7 g, about 2.8 g, about
2.9 g, or about 3.0 g.
[0055] Suitable rate of acquisition values determined by the Medi-Cal
method fall within
the range of about 110 sec to about 180 sec, e.g., about 110 sec, about 115
sec, about 120 sec,
about 125 sec, about 130 sec, about 135 sec, about 140 sec, about 145 sec,
about 150 sec, about
155 sec, about 160 sec, about 165 sec, about 170 sec, about 175 sec or about
180 sec.
[0056] The "Max Lift Weight" is the maximum weight the pad can support
while being
lifted at two or more points without tearing. The Max Lift Weight can be
tested by attaching
clamps to at least two edges or corners of the pad and placing weights on the
pad. The clamps
can then be attached to a lifting device. (Figure 2). In certain embodiments
of the invention, the
absorbent pad has a Max Lift Weight in the range of up to about 415 lbs to up
to about 100 lbs.
For Example, the absorbent pad of the present invention can have a Max Lift
Weight of up to
about 415 lbs, up to about 370 lbs, up to about 325 lbs, up to about 280 lbs,
up to about 235 lbs,
up to about 190 lbs, up to about 145 lbs, or up to about 100 lbs.
[0057] In a particular embodiment of the invention, the absorbent pad,
after exposure to
about 1 mL to about 500 mL of ASTM synthetic urine or a 1% saline solution has
a Max Lift
Weight in the range of up to about 415 lbs to up to about 100 lbs. For
example, the absorbent
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pad of the present invention can have a Max Lift Weight after exposure to
about 1 mL to about
1000 mL of ASTM synthetic urine or a 1% saline solution of up to about 325
lbs, of up to about
415 lbs, up to about 370 lbs, up to about 325 lbs, up to about 280 lbs, up to
about 235 lbs, up to
about 190 lbs, up to about 145 lbs, or up to about 100 lbs.
[0058] In some embodiments of the invention, the absorbent pad has tensile
strength at
break, when measured by the ASTM D 882 method, in the range of about 50 N/25
mm to about
90 N/25 mm in the machine direction. For example, the pad can have a tensile
strength at break
in the machine direction of about 50 N/25 mm, about 60 N/25 mm, about 70 N/25
mm, about 80
N/25 mm, or about 90 N/25 mm, inclusive of all ranges and subranges
therebetween.
[0059] In other embodiments of the invention, the absorbent pad has tensile
strength at
break, when measured by the ASTM D 882 method, in the range of about 30 N/25
mm to about
60 N/25 mm in the cross direction. For example, the pad can have a tensile
strength at break in
the cross direction of about 30 N/25 mm, about 35 N/25 mm, about 40 N/25 mm,
about 45 N/25
mm, about 50 N/25 mm, about 55 N/25 mm, or about 60 N/25 mm, inclusive of all
ranges and
.. subranges therebetween.
[0060] In another embodiment of the invention, the elongation at break
of the absorbent
pad, when tested by the ASTM D 882 method, is in the range of about 35% to
about 115% in the
machine direction. For example, the pad can have an elongation at break in the
machine
direction of about 35%, about 55%, about 45%, about 65%, about 75%, about 85%,
about 95%,
about 105% or about 115%, inclusive of all ranges and subranges therebetween.
[0061] In a particular embodiment of the invention, the elongation at
break of the
absorbent, when tested by the ASTM D 882 method, is in the range of about 45%
to about 105%
in the cross direction. For example, the pad can have an elongation at break
in the cross
direction of about 45%, about 55%, about 65%, about 75%, about 85%, about 95%,
or about
105%, inclusive of all ranges and subranges therebetween.
[0062] In particular embodiments of the invention, the absorbent pad
has a tensile
strength at 25% elongation, when measured by the ASTM D 882 method, in the
range of about
N/25 mm to about 55 N/25 mm in the machine direction. For example, the
absorbent pad can
have a tensile strength at 25% elongation in the machine direction of about 35
N/25 mm, about
30 40 N/25 mm, about 45 N/25 mm, about 50 N/25 mm, or about 55 N/25 mm,
inclusive of all
ranges and subranges therebetween.
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[0063] In a particular embodiment of the invention, the absorbent pad
has tensile strength
at 25% elongation, when measured by the ASTM D 882 method, in the range of
about 20 N/25
mm to about 40 N/25 mm in the cross direction. For example, the absorbent pad
can have a
tensile strength at break in the cross direction of about 20 N/25 mm, about 25
N/25 mm, about 30
N/25 mm, about 35 N/25 mm, or about 40 N/25 mm, inclusive of all ranges and
subranges
therebetween.
[0064] In a particular embodiment of the invention, a single absorbent
pad of the present
invention is placed under an incontinent individual, and the single absorbent
pad absorbs fluids,
protects skin dryness and/or protects the bedding from fluids. Protecting skin
dryness means the
individual's skin which is in contact with the pad remains reasonably dry
after the pad has been
exposed to urine or other fluids. Protecting the bedding means that less than
10% of the urine or
other fluid which is expelled onto the pad makes contact with the bedding
underneath the pad. In
yet another embodiment of the invention, at least one caregiver can lift or
reposition the patient
by lifting the single absorbent pad of the present invention, disposed beneath
the patient, at two
or more edges or corners.
EXAMPLES
Example 1
A. Absorbent Pad
[0065] The first layer is a spunbond, nonwoven with a weight of 16.96
gsm (PGI). The
second layer is a thermobonded absorbent airlaid core made from 103 gsm
macerated wood pulp
and 25 gsm of super absorbent polymer (Super Core McAirlaids). The third
layer is an air
permeable PE film with a weight of 35 gsm and a MVTR of 3,600g/m2/day (PGI).
The fourth
layer is a 50 gsm spunbond nonwoven back sheet (PG1). The top layer and the
edges where the
layers meet are glued together using hot melt adhesive.
B. Strength Testing
[0066] The strength of the pad from Example IA was tested with ASTM E
252 to
measure the basis weight and ASTM D 882 to measure tensile strength and
elongation at break.
The results are shown in Table I:
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pirmnipiww1rx:rilri:i9imilri:i9p:ilrmiimmuwaitivgigidommmmmil
Basis Weight 71.5 6 g/m2
Tensile Strength at break in the 70 16 N/25 mm
Machine Direction
Tensile Strength at break in the 45 10 N/25 mm
Cross Direction
Elongation at Break in the 75 40 %
Machine Direction
Elongation at Break in the Cross 75 30 %
Direction
Tensile Strength at 25% 47 8 N/25 mm
Elongation in the
Machine Direction
Tensile Strength 25% Elongation 28 8 N/25 mm
in the Cross Direction
C. Max Lift Weight Testing
[0067] The Max Lift Weight was tested by placing the pad flat on the
ground with the
first layer up, loading weights on top of the pad and centering the weights.
The corners of the
pad were clamped into the lifting device as shown in Figure 2. The absorbent
pad and weights
were lifted 2-3 inches above the ground for two minutes, while observing any
tearing or other
failures to the structural integrity of the pad. The testing was repeated
until failure. The
absorbent pad of Example lA was held for two minutes with 415 lbs with no
observed tearing or
ripping.
[0068] The wet Max Lift Weight was tested in a similar manner after
applying 500 cc of
liquid to the absorbent pad. The absorbent pad of Example 1A was held for two
minutes with
425 lbs with no observed tearing or ripping.
17