U.S. patent number 3,916,900 [Application Number 05/519,415] was granted by the patent office on 1975-11-04 for multilayer one-piece disposable diapers.
This patent grant is currently assigned to Scott Paper Company. Invention is credited to Walter Herman Breyer, Nathan Allen Edelson, Barbara Faye Gilliland, Clarence Henry Schatz.
United States Patent |
3,916,900 |
Breyer , et al. |
November 4, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Multilayer one-piece disposable diapers
Abstract
Multilayer, one-piece, disposable diapers including a
moisture-pervious facing layer adapted to be positioned in
engagement with a wearer; a fibrous absorbent core disposed beneath
the facing layer for absorbing body fluids which pass through the
facing layer; an elastomeric, wet-stable foam layer beneath the
absorbent core for confining and maintaining the absorbent core in
close conformity with the perineal region of the wearer, and having
sufficient longitudinal and tranverse dimensions for providing
elasticity in regions of the diaper that are disposed about the
thighs and front and back of the wearer; a moisture-impervious
backing sheet beneath the foam layer for preventing fluids from
striking through the diaper; and bonding means for retaining the
layers of each diaper in an assembled, one-piece construction.
Inventors: |
Breyer; Walter Herman
(Wallingford, PA), Edelson; Nathan Allen (Bala Cynwyd,
PA), Gilliland; Barbara Faye (Blackwood, NJ), Schatz;
Clarence Henry (West Chester, PA) |
Assignee: |
Scott Paper Company
(Philadelphia, PA)
|
Family
ID: |
24068223 |
Appl.
No.: |
05/519,415 |
Filed: |
October 31, 1974 |
Current U.S.
Class: |
604/365; 604/368;
604/369; 604/370; 604/372; 604/373; 604/375; 604/378; 604/389 |
Current CPC
Class: |
A61F
13/49446 (20130101); A61F 13/51474 (20130101); A61F
13/515 (20130101); A61F 13/51478 (20130101); A61F
13/49001 (20130101); A61F 13/539 (20130101); A61F
13/49413 (20130101); A61F 2013/530802 (20130101); A61F
2013/530131 (20130101); A61F 2013/53445 (20130101); A61F
2013/51409 (20130101); A61F 2013/53721 (20130101); A61F
2013/530481 (20130101); A61F 13/534 (20130101); A61F
13/537 (20130101) |
Current International
Class: |
A61F
13/15 (20060101); A41B 013/02 (); A61F
013/16 () |
Field of
Search: |
;128/284,287,285,29P,29R,288 ;161/49 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Medbery; Aldrich F.
Attorney, Agent or Firm: Faigus; Martin L. Foley; William
J.
Claims
Having described our invention we claim the following:
1. A multilayer, one-piece, disposable diaper including:
A. a moisture-pervious facing layer adapted to be positioned in
engagement with a wearer;
B. an absorbent core containing hydrophilic fibers disposed beneath
said facing layer for absorbing and retaining body fluids which
pass through said facing layer;
C. an elastomeric, wet-stable foam layer beneath said absorbent
core for confining and maintaining the absorbent core in the
perineal region of the wearer, said foam layer having sufficient
longitudinal and transverse dimensions for providing elasticity in
regions of the diaper that are disposed about the thighs and front
and back of the wearer;
D. a moisture-impervious backing sheet beneath said foam layer;
and
E. bonding means for retaining the components of the disposable
diaper in an assembled, one-piece construction.
2. The disposable diaper according to claim 1, wherein the
absorbent core is the heaviest hydrophilic component.
3. The disposable diaper according to claim 1, including
double-pleat folds at each side margin thereof.
4. The disposable diaper according to claim 1, wherein said bonding
means includes adhesive bonds adhering the backing sheet to the
foam layer in spaced apart regions.
5. The disposable diaper according to claim 4, including pressure
sensitive adhesive tabs secured to the backing sheet for use in
retaining the diaper about the torso of a wearer.
6. The disposable diaper according to claim 1, including a fibrous
wicking layer disposed between the foam layer and backing
sheet.
7. The disposable diaper according to claim 6, wherein said bonding
means includes adhesive bonds adhering the backing sheet to the
foam layer.
8. The disposable diaper according to claim 7, including pressure
sensitive adhesive tabs secured to the backing sheet for use in
retaining the diaper about the torso of a wearer.
9. The disposable diaper according to claim 1, wherein said foam
layer has a thickness in the range of from about 0.015 inches to
about 0.250 inches and a density in the range of from about 0.5
lbs. per cubic ft. to about 10 lbs. per cubic ft.
10. The disposable diaper according to claim 9, wherein said foam
layer has a thickness in the range of from about 0.015 inches to
about 0.080 inches and a density in the range of from about 1.0
lbs. per cubic ft. to about 2.5 lbs. per cubic ft.
11. The disposable diaper according to claim 1, wherein said
absorbent core includes a loosely compacted fibrous batt and the
foam layer is wider and longer than said batt.
12. The disposable diaper according to claim 11, wherein said
fibrous batt is the heaviest hydrophilic component.
13. The disposable diaper according to claim 11 including
double-pleat folds at each side margin thereof.
14. The disposable diaper according to claim 11, wherein the
loosely compacted batt is of a shaped construction having a central
region which is narrower than forward and rearward regions
thereof.
15. The disposable diaper according to claim 11, wherein the width
of the foam layer is greater than one-half the width of the
diaper.
16. The disposable diaper according to claim 15, wherein said foam
layer has a length which is substantially equal to the length of
the diaper.
17. The disposable diaper according to claima 1, wherein said
absorbent core includes a loosely compacted batt of absorbent
fibers, said batt having a narrower transverse dimension than that
of the foam layer.
18. The disposable diaper according to claim 17, wherein said
fibrous batt is the heaviest hydrophilic component.
19. The disposable diaper according to claim 17 including
double-pleat folds at each side margin thereof.
20. The disposable diaper according to claim 17, wherein said
absorbent core also includes a fibrous wicking layer having a
greater density than said batt and contiguous to a bottom surface
of said batt.
21. The disposable diaper according to claim 20, including a second
fibrous wicking layer having a greater density than said batt
disposed between the foam layer and backing sheet.
22. The disposable diaper according to claim 21, wherein said
bonding means includes adhesive bonds adhering the backing sheet to
the foam layer.
23. The disposable diaper according to claim 22, including pressure
sensitive adhesive tabs adhered to the backing sheet for use in
retaining the diaper about the torso of a wearer.
24. The disposable diaper according to claim 17, including a
fibrous wicking layer having a greater density than said batt
diposed between said foam layer and backing sheet.
25. The disposable diaper according to claim 24, wherein said
bonding means includes spaced apart adhesive bonds adhering the
backing sheet to the foam layer.
26. The disposable diaper according to claim 25, including pressure
sensitive adhesive tabs adhered to the backing sheet for use in
retaining the diaper about the torso of a wearer.
27. The disposable diaper according to claim 17, wherein said batt
is of a shaped construction having a central region which is
narrower than forward and rearward regions thereof.
28. The disposable diaper according to claim 27, wherein said foam
layer has a thickness in the range of from about 0.015 inches to
about 0.250 inches and a density in the range of from about 0.5
lbs. per cubic ft. to about 10 lbs. per cubic ft.
29. The disposable diaper according to claim 27, wherein said foam
layer has a thickness in the range of from about 0.015 inches to
about 0.080 inches and a density in the range of from about 1.0
lbs. per cubic ft. to about 2.5 lbs. per cubic ft.
30. The disposable diaper according to claim 29, wherein said foam
layer is a polyurethane foam.
31. The disposable diaper according to claim 29, wherein said
bonding means includes adhesive bonds adhering the backing sheet to
the foam layer in spaced apart regions.
32. The disposable diaper according to claim 31, including pressure
sensitive adhesive tabs adhered to the backing sheet for use in
retaining the diaper about the torso of a wearer.
33. The disposable diaper according to claim 32, wherein said
absorbent core also includes a fibrous wicking layer having a
greater density than said fibrous batt and disposed adjacent a
bottom surface of said batt.
34. The disposable diaper according to claim 33, including a second
fibrous wicking layer having a greater density than said fibrous
batt disposed between the foam layer and the backing sheet.
35. A multilayer, one-piece, disposable diaper including:
A. a moisture-pervious facing layer adapted to be positioned in
engagement with a wearer;
B. an absorbent core containing hydrophilic fibers disposed beneath
said facing layer for absorbing and retaining body fluids which
pass through said facing layer;
C. an elastomeric, wet-stable foam layer beneath said absorbent
core for confining and maintaining the absorbent core in the
perineal region of the wearer, said foam layer being wider than
said absorbent core and having sufficient longitudinal and
transverse dimensions for providing elasticity in regions of the
diaper that are disposed about the thighs and front and back of the
wearer;
D. a moisture-impervious backing sheet beneath said foam layer;
and
E. bonding means for retaining the components of the disposable
diaper in an assembly, one-piece construction.
36. The disposable diaper according to claim 35, wherein said foam
layer is hydrophobic.
37. The disposable diaper according to claim 35, wherein said
absorbent core includes a loosely compacted batt of absorbent
fibers and a fibrous wicking layer contiguous to a bottom surface
of said batt and having a greater density than said batt.
38. The disposable diaper according to claim 37, wherein the
loosely compacted batt is of a shaped construction having a central
region which is narrower than forward and rearward regions
thereof.
39. A multilayer, one-piece, disposable diaper including:
A. a moisture-pervious facing layer adapted to be positioned in
engagmenet with a wearer;
B. an absorbent fibrous core predominately of hydrophilic fibers,
said absorbent core being disposed beneath said facing layer for
absorbing and retaining body fluids which pass through said facing
layer;
C. an elastomeric, wet-stable foam layer beneath said absorbent
core for confining and maintaining the absorbent core in the
perineal region of the wearer, said foam layer having sufficient
longitudinal and transverse dimensions for providing elasticity in
regions of the diaper that are disposed about the thighs and front
and back of the wearer;
D. a moisture-impervous backing sheet beneath said foam layer;
and
E. bonding means for retaining the components of the disposable
diaper in an assembled, one-piece construction.
40. The disposable diaper according to claim 39, wherein said
fibrous absorbent core has a narrower transverse dimension than
that of the foam layer.
41. The disposable diaper according to claim 40, wherein said foam
layer is hydrophobic.
42. The disposable diaper according to claim 41, wherein said
absorbent core includes a loosely compacted batt of absorbent
fibers and a fibrous wicking layer contiguous to a bottom surface
of said batt and having a greater density than said batt.
43. The disposable diaper according to claim 42, wherein said
loosely compacted batt is of a shaped construction having a central
region which is narrower than forward and rearward regions thereof.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to disposable diapers, and more specifically
to multilayer, one-piece, disposable diapers.
2. Description of the Prior Art
Disposable diapers have become exceedingly popular in recent years.
Commercially, the most successful diapers have been of a
multilayer, one-piece construction including a facing layer which
is pervious to body fluids, an intermediate absorbent core for
absorbing and retaining body fluids which pass through the facing
layer, and a moisture-impervious backing sheet beneath the
absorbent core for preventing body fluids from striking through the
diaper. The absorbent cores in the most popular one-piece
disposable diapers include a loosely compacted batt of wood pulp
fibers.
It is well known that disposable diapers should be constructed to
retain body fluids without leakage therefrom. In an effort to
prevent, or minimize leakage, prior art disposable diapers include
fluff cores having a weight of hydrophilic fibers that, based on
theoretical calculations, is sufficient to absorb the volume of
body fluids which is discharged under the specific conditions of
use for which the diaper is designed, e.g., daytime, overnight,
infant, toddler, geriatric etc. However, when these fluff cores
become wet they become considerably weakened, and the stresses
imposed on them by normal body movements of a wearer cause them to
break up into clumps or rope-like elements. This breaking up of the
absorbent cores causes the diapers to lose much of their
fluid-retaining capability; thereby resulting in leakage of body
fluids from within the confines of the diapers.
To avoid the problem of the absorbent core breaking up it has been
suggested in U.S. Pat. No. 3,563,243, issued to Lindquist, to
utilize a hydrophilic polymer foam layer as the primary absorbent
component in place of a fibrous absorbent core. For uses in which
the diaper is required to absorb a large volume of body fluids
(e.g. toddler or overnight uses) a relatively heavy polymer layer
is required. Such a heavy polymer layer is quite expensive, and
therefore is not desirably utilized in single use products, such as
disposable diapers. Moreover, the hydrophilic foams contemplated
for use by Lindquist become plasticized by absorbed body fluids and
this adversely affects the elastic properties of the diaper during
use. This adverse affect on the elastic properties of the diaper
can cause the diaper to lose its close conformity with a wearer's
torso to create gaps through which body fluids can easily
escape.
Several approaches have been suggested to compensate for the loss
in the fluid-retaining capability of the prior art disposable
diapers which results from the inadequate conformity of the diapers
to a wearer and the breaking up of the fluff cores. One approach
which has been suggested, and which actually is employed in
commercially available diapers, is to provide a specialty fold
construction in the diaper to act as a dam for body fluids impinged
within the confines thereof. This approach is illustrated in U.S.
Pat. No. Re 26,151, issued to Duncan et al, and U.S. Pat. No.
3,196,874, issued to Hrubecky. Another approach which has been
suggested is to include foam strips on the surface of the diaper to
form a gasket-like seal with the body of a wearer. This approach is
illustrated in U.S. Pat. No. 3,572,342, issued to Lindquist et al.
Still another approach is to include multiple tape fasteners on the
diaper, at least one of the fasteners being adjacent the
thigh-encircling regions of the diaper to establish a tight fit
about the thighs. This approach is illustrated in U.S. Pat. No.
3,221,738.
Although some of the above-discussed approaches may be beneficial
in reducing leakage, there is still a need for further
improvement.
SUMMARY OF THE INVENTION
Multilayer, one-piece, disposable diapers according to this
invention each include a moisture-pervious facing layer adapted to
be positioned in engagement with a wearer; a fibrous absorbent core
disposed beneath the facing layer for absorbing and retaining body
fluids which pass through said facing layer an elastomeric,
wet-stable foam layer disposed beneath the fibrous absorbent core
for confining and maintaining said core in the peripheral region of
the wearer, said foam layer having sufficient longitudinal and
transverse dimensions for providing elasticity in regions of the
diaper that are disposed about the thighs and front and back of the
wearer; a moisture-impervious backing sheet beneath said foam layer
for preventing body fluids from striking through the diaper; and
bonding means for retaining the layers of each diaper in an
assembled, one-piece construction.
The term "one-piece", as used throughout this application to
characterize a diaper, refers to a diaper having separate layers
which are integrated into a single unit by suitable bonding means,
and, with the possible exception of fastening menas for retaining
the diaper about a wearer's torso, does not require the inclusion
or attachment of additional components to render it usable. The
bonding means for retaining the layers in a one-piece construction
need not bond each layer to an adjacent layer.
The term "disposable", as used throughout this application to
characterize diapers, refers to diapers which are adapted for a
single use, i.e., they are not capable of being washed and
reused.
The term "elastomeric", as used throughout this application to
describe the foam layer, refers to a flexible, resilient foam
layer, a 1 inch wide sample of which has the ability, at room
temperature, to recover to at least 80%, and preferably to over
90%, of its original length after being gripped in opposed jaws of
an Instron tensile tester which are initially spaced 2 inches
apart, stretched to twice its original length (4 inches) at a jaw
speed of 10 inches per minute, held in its stretched condition for
1 minute and allowed to recover for 10 minutes.
The term "wet-stable", as used throughout this application to
describe the foam layer, refers to the ability of the foam layer,
after being submerged in water for twelve hours, to exhibit the
above-described elastomeric property and to retain substantially
the same dimensions it had when dry. For purposes of this invention
the wet foam layer is considered to retain substantially the same
dimensions as the dry foam layer if the length and width of the wet
foam layer is less than 15% greater than the corresponding
dimensions of the dry foam layer.
A multilayer, one-piece, disposable diaper of this invention is
positioned about the torso of a wearer with the foam layer thereof
in a stretched, elastic condition, and the diaper is retained in
this stretched, elastic condition by suitable fastening means, such
as conventional tape fasteners adhered to the moisture-impervious
backing sheet of said diaper. This stretched, elastic condition of
the foam layer aids in establishing close elastic conformity of the
diaper about the thighs and waist region of a wearer, and this
close conformity will be maintained when the diaper is wet due to
the wet-stable property of the foam layer. Establishing and
maintaining this close conformity aids in preventing leakage of
body fluids from the diaper during usage thereof.
The elastomeric, wet-stable foam layer, by virtue of being
positioned beneath the fibrous absorbent core, will confine the
absorbent core in close conformity with the perineal region of a
wearer when the diaper is positioned about its torso in a
stretched, elastic condition, and will function to maintain the
absorbent core in its position of close conformity with the
perineal region during normal usage of the diaper. In this
position, the absorbent core can best receive and contain body
fluids.
In a preferred embodiment of this invention the absorbent core
includes a loosely compacted fibrous batt and the foam layer is
wider and longer than said batt. Therefore, the foam layer confines
the complete fibrous batt during usage of the diaper. This
arrangement provides the best conformity of the batt within the
perineal region of a wearer to thereby enhance the fluid-retaining
capability of the diaper. Most preferably the foam layer has a
width which is greater than one-half the width of the diaper, and a
length substantially equal to the length of the diaper.
In the most preferred embodiment of the invention the fibrous batt
is shaped so that a central region thereof has a lesser transverse
dimension than forward and rearward regions, respectively. This
shaped construction permits the batt to conform in a most optimum
manner to the perineal region of a wearer. When the fibrous batt
closely conforms in shape to the perineal region of a wearer it is
less likely to encounter excessive stresses resulting from normal
body movements. Excessive stresses imposed on the batt can cause it
to excessively break up, and thereby lose a significant portion of
its fluid-retaining capability. This loss in fluid-retaining
capability results in undesirable leakage from the diaper.
The loosely compacted batt has excellent fluid-retaining
capabilities; however, due to the relatively large capillaries
associated with the batt, it does not enhance the fluid
transmission rate by readily wicking body fluids along either the
transverse or longitudinal extent thereof. For some applications
the enhancement of fluid transmission is not necessary, and the
loosely compacted batt can constitute the entire absorbent
core.
For applications wherein a likelihood of overflooding exists the
absorbent core also includes a wicking layer, which may be in the
form of a fibrous sheet having a greater density than the fibrous
batt, disposed in engagement with the lower surface of said batt.
In this embodiment urine which passes through the fibrous batt will
be received and distributed by the wicking layer. If the wicking
layer becomes over saturated the fluid will pass either into dry
portions of the batt to effectively utilize the absorbent capacity
of the batt, or into the foam layer. The foam layer is of a
relatively low density having large void areas, and does not
function effectively to wick body fluids which pass into it.
However, the void areas do have the ability to retain some amount
of urine therein, and the fluid-impervious backing layer prevents
this urine from striking through the backside of the diaper.
If desired, a wicking layer can also be positioned adjacent the
lower surface of the foam layer, between the foam layer and the
moisture-impervious backing sheet. This wicking layer functions to
wick urine which may pass through the foam layer to distribute the
urine within the diaper. In the event that this wicking layer
becomes over saturated the urine will be forced back through the
foam layer (by virtue of its high void, low density construction)
wherein it is either retained, or from where it moves into the
absorbent fluff batt.
Other objects and advantages of this invention will become apparent
by reading the detailed description which follows taken in
conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially exploded isometric view of a multilayer,
one-piece, disposable diaper according to this invention;
FIG. 2, shows the diaper of FIG. 1 in an assembled and folded
condition;
FIG. 3, is a sectional view along line 3--3 of FIG. 2;
FIG. 4, is a sectional view similar to FIG. 3, but showing a second
embodiment of a multilayer, one-piece, disposable diaper according
to this invention; and
FIG. 5 is a sectional view similar to FIG. 3, but showing a third
embodiment of a multilayer, one-piece, disposable diaper according
to this invention. In this Figure the sectional view terminates
short of the edges so that the folded side sections of the diaper
are not shown.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, a preferred embodiment of a multilayer,
one-piece, disposable diaper 10 of this invention includes a
moisture-pervious facing layer 12; an absorbent core 14 including a
loosely compacted fibrous batt 15 and a fibrous wicking layer 16
having a greater density than said fibrous batt 15; an elastomeric,
wet-stable foam layer 18; and a moisture-impervious backing sheet
20.
The moisture-pervious facing layer 12 can be of any construction
which permits body fluids initially impinged thereon to pass into
the internal absorbent core 14. Representative facing layers which
can be employed in this invention are carded rayon webs,
water-wettable bonded webs of mixed long and short fibers, slit
plastic webs and laminates of paper and textile fibers. The
specific construction of the facing layer 12 is not intended to be
a limitation on the broadest aspects of the instant invention.
In the preferred embodiment the absorbent core 14 is the primary
absorbent component i.e. it is the heaviest hydrophilic component
of the diaper 10. Preferably the absorbent core 14 includes a
loosely compacted fibrous batt 15 containing cellulosic fibers of a
papermaking length less than one-fourth inch. The batt also can
contain some longer fibers to enhance its integrity. In addition,
the batt can contain various additives, as desired. For example,
insoluble hydrophilic homopolymers and copolymers which form a gel
upon absorption of water can be added.
Most preferably, the fibrous batt 15 is formed from 100% wood pulp
fibers by directing a pulp lap, in roll or sheet form, through a
fiberizer which separates the fibers from the lap, and by directing
the separated fibers onto a carrier as a loosely compacted batt.
One fiberizer which is commonly employed to form such a loosely
compacted batt is the Joa fiberizer manufactured by Joa, Inc. of
North Wales, Fla.
In the most preferred embodiment of this invention the fibrous batt
15 is shaped so that a central region 22 has a narrower transverse
dimension than a forward region 24 and a rearward region 26
thereof. In the embodiment shown in FIG. 1 the fibrous batt 15 has
an hour-glass shape with continuous, concavely curved side margins
28; however, other shaped configurations can be employed. The
shaped fibrous batt 15 can be manufactured by employing apparatus
of the type disclosed in U.S. patent application Ser. No. 237,963,
filed Mar. 24, 1972, and assigned to Scott Paper Company. The
subject matter relating to the formation of a shaped pad is
incorporated by reference into the instant application.
The wicking layer 16 of the absorbent core 14 can be of many
different constructions, such as a layer or layers of wet-formed or
dry formed fibrous webs. The specific construction of the wicking
layer 16 is not intended to be a limitation on the broadest aspects
of the instant invention; however, the wicking layer 16 must have a
sufficiently small pore size to perform its wicking function.
Accordingly, in the preferred embodiment of this invention in which
the fibrous batt 15 is a loosely compacted assemblage of cellulosic
fibers, the wicking layer 16 has a greater density than said
fibrous batt.
The elastomeric, wet-stable foam layer 18 must be sufficiently
thick to retain its cellular structure; however, it should not be
so thick as to impart an undesirable bulkiness to the diaper. If
the foam layer is too thick, the excessive bulk in the diaper will
result in an uncomfortable structure for a wearer, and also will
prevent the desired conformability of the diaper to a wearer's
torso. Also, the upper thickness limitation of the foam layer 18 is
dictated by economic considerations. Specifically, a thick foam
layer includes a greater weight of material than a thin foam layer
of the same density, and accordingly is most costly to
manufacture.
The elastomeric, wet-stable foam layer 18 employed in the
disposable diaper 10 of this invention has a thickness in the range
of from about 0.015 inches to about 0.250 inches, and more
preferably, in the range of from about 0.015 inches to about 0.080
inches. The foam layer 18 has a density in the range of from about
0.5 lbs. per cubic ft. to about 10 lbs. per cubic ft., and more
preferably in the range of from about 1 lb. per cubic ft. to about
2.5 lbs. per cubic ft. The lower the density of the foam layer 18,
the less material that is required to form a layer of a given
thickness. Accordingly, a low density foam layer contributes
favorably to the economics of the disposable diapers of this
invention.
The foam layer 18 must be of a cellular construction having the
elastomeric, wet-stable properties described earlier in this
application. Representative foams which may be employed in this
invention are synthetic and natural rubber foams, vinyl foams,
polyvinyl chloride foams and polyurethane foams of both the
polyester and polyether type.
The preferred elastomeric, wet-stable foam layer 18 employed in
this invention is formed from polyester of polyether polyurethane
foam. The polyurethane foams can be either hydrophobic or
hydrophilic, the only requirement being that they be both
elastomeric and wet-stable. The hydrophobic polyurethane foams are
most preferred because they are less expensive than the hydrophilic
polyurethane foams.
The moisture-impervious backing sheet 20 can be formed of any of
the well known materials employed as backing sheets in disposable
diapers. For example, the moisture-impervious sheet 20 can be a
relatively thin sheet having a thickness of approximately 0.001
inches to about 0.002 inches, and formed from suitable plastics
such as polyethylene or polypropylene. The specific material from
which the backing sheet 20 is formed is not intended to be a
limitation on the broadest aspects of the instant invention;
however, the backing sheet 20 should be moisture-impervious to
prevent body fluids from striking through the diaper.
Referring to FIGS. 1 and 3, the absorbent core 14 is disposed in
overlying relationship with the elastomeric, wet-stable foam layer
18. Preferably, the foam layer 18 has side margins 30 which extend
beyond the side margins 28 of the fibrous batt 15 of the absorbent
core 14 to completely confine said fibrous batt when the diaper 10
is placed about the torso of a wearer.
Referring to FIG. 3, the moisture-impervious backing sheet 20 is
adhered to both the foam layer 18 and the infolded side panels 12'
of the facing layer 12 along spaced longitudinally extending
adhesive lines 32. In this manner the components of the diaper 10
are retained in an assembled one-piece construction. When the
disposable diaper 10 is stretched about the torso of a wearer, by
engaging pressure sensitive adhesive tapes 34 (FIGS. 1 and 2) which
are attached to the backing sheet 20, the stretching forces imposed
on said moisture-impervious backing sheet will be transmitted to
the foam layer 18 through the adhesive lines 32 and the frictional
engagement between the backing sheet and the foam layer to thereby
stretch the foam layer 18. In this manner the multilayer,
one-piece, disposable diaper 10 is placed about the torso of a
wearer with the foam layer 18 in a stretched, elastic condition.
The foam layer 18, by virtue of being elastomeric, has a memory for
its unstretched condition, and accordingly, will conform to the
thigh and waist regions of a wearer to provide a well fitting
garment about its torso. Moreover, due to the elastomeric property
of the foam layer 18, the diaper 10 will readily conform to the
perineal region of the wearer, and thereby confine the fibrous batt
15 of the absorbent core 14 in close conformity with the perineal
region so that it will be in proper position for receiving body
fluids as they pass through the facing layer 12.
In the most preferred embodiment of this invention, as indicated
earlier in this application, the fibrous batt 15 is of a reduced
width as compared to the width of the diaper 10, and is shaped to
provide a central region 22 which is narrower than forward and
rearward regions 24 and 26, respectively. This construction of the
fibrous batt 15 has been found to be most suitable for conforming
to the perineal region of a wearer without encountering excessive
stresses during use of the diaper which could cause the fibrous
batt to excessively break up into clumps, or rope-like elements,
and thereby lose a significant amount of its fluid-retaining
capability.
Referring to FIGS. 1 and 3, the foam layer 18 extends for
substantially the full longitudinal and transverse extents of the
disposable diaper 10. Accordingly, when the diaper 10 is
double-pleat folded at opposed side margins along fold lines 36,
38, 40 and 42, the foam layer is included in the inner panels 44
and 46, and in the outer panels 48 and 50 of said folds. Both the
inner and outer panels are adapted to encircle the thighs of a
wearer, and accordingly, the stretched foam layer aids in
maintaining the diaper 10 in close conformity with the thighs. In
addition, the foam layer 18 will circumscribe the waist region of
the wearer in a stretched condition to establish excellent elastic
conformity therewith.
Referring to FIG. 4, a second embodiment of a multilayer,
one-piece, disposable diaper 10A is shown in which an elastomeric
foam layer 18A, is identical to foam layer 18, but terminates short
of the transverse ends of the diaper. In this embodiment the foam
layer 18 is included only in the inner panels 44 and 46 of the
double-pleat folds; however, these inner panels are adapted to
encircle the thigh regions of wearer, and accordingly, the foam
layer 18A has a sufficient transverse dimension for closely
conforming to the thighs of a wearer. In all other respects the
disposable diaper 10A is identical to the disposable diaper 10
disclosed in FIGS. 1-3.
Referring to FIG. 5, a third embodiment of a multilayer, one-piece,
disposable diaper 10B is shown. The diaper 10B includes a wicking
layer 60 disposed between the foam layer 18 and the backing sheet
20. This wicking layer 60 functions to distribute the urine which
may pass into it through the absorbent core 14, the wicking layer
16 and the foam layer 18. In the event that the lower wicking layer
60 becomes over saturated the urine will be forced upwardly into
the capillary structure of the foam layer 18, wherein the urine can
be retained. The urine is confined against passage through the
backing sheet 20 due to its moisture-impervious property.
The backing sheet 20 in the disposable diaper 10B is connected to
the foam layer 18 by adhesive lines 32B. The adhesive lines 32B
underlying the wicking layer 60 can strike through the wicking
layer to adhere to the foam layer 18; however, this construction is
optional.
Several modifications of the disposable diapers described above are
considered to be within the scope of this invention. First, it is
within the scope of the invention to omit one or both of the
wicking layers 16 and 60. In some uses of a disposable diaper the
ultimate absorptive capacity of the diaper may be more important
than its rate of absorption. For such uses it may be desired to
include a greater weight of loosely compacted fibrous material in
the fluff batt 15 to replace the weight of fibers contributed by
the wicking layer(s). In an overnight diaper for a very small
infant, for example, the total discharge of several voidings may
make added absorptive capacity desirable while the rate of
discharge in any one voiding may not be so great as to tax the
absorption rate of the loosely compacted batt. Accordingly, for
such a use it is not necessary to include a wicking layer to aid in
distributing the flow of urine.
Secondly, although the densified wicking layers 16 and 60 are shown
as extending for less than the full transverse extent of the
diaper, it is within the scope of this invention to employ wicking
layer(s) of a larger transverse dimension. However, when wicking
layer 16 is employed as part of the absorbent core 14 it should
underlie the entire fibrous batt 15 to both aid in supporting the
batt and in distributing the urine. When the wicking layer 16
extends to the side and/or end margins of the diaper, said wicking
layer should be of a capillary structure which will not wick an
excessive quantity of urine to the boundaries of the diaper to
create a leakage problem.
The particular manner in which the diaper is folded is not
considered to be a critical limitation on the broadest aspects of
this invention; however, combining the structural elements of this
invention with the double-pleat folds described earlier is
considered to be most desirable. It is contemplated that the diaper
could be sold without the side margins thereof being folded in any
manner.
Although less preferred, it is within the scope of this invention
to provide an absorbent core 14 including a loosely compacted
fibrous batt which is substantially rectangular, and which extends
for the full transverse extent of the unstretched, elastomeric,
wet-stable foam layer 18. Even in this construction the stretching
of the diaper, including the foam layer 18 therein, about the torso
of an infant tends to confine the fibrous batt in the perineal
region of the wearer by virtue of the elastomeric property of the
foam and the natural pleating of the diaper which takes place in
the perineal region. However, a substantially rectangular fibrous
batt, as described above, may be subjected to excessive forces
resulting from the normal body movements of a wearer to thereby
cause the batt to excessively break up into clumps or rope-like
elements, and thereby lose a significant portion of its
fluid-retaining ability.
The particular dimensions of the multilayer, one-piece, disposable
diapers of this invention will vary depending upon the intended use
of the diaper, i.e. infant, toddler, daytime, overnight, geriatric,
etc. However, by way of illustration, a representative multilayer,
one-piece, disposable diaper according to this invention, and
intended for daytime use, has a transverse dimension of 121/2
inches and a longitudinal dimension of 17 inches. The
moisture-impervious backing sheet 20 has the same dimensions as the
diaper, and the moisture-pervious facing layer 12 has a slightly
greater transverse dimension so that end margins 12' thereof can be
folded inwardly between the foam layer 18 and the
moisture-impervious backing sheet 20 and bonded to the backing
sheet (FIG. 1). The foam layer 18 has the same dimensions as the
diaper, and is positioned in engagement with the
moisture-impervious backing sheet 20, except for the transverse
ends thereof which are separated from the backing sheet 20 by the
end margins of the folded end portions 12' of the moisture-pervious
facing layer 12. The absorbent core 14 includes a loosely compacted
fibrous batt 15 which has a substantially hour-glass shape in which
the central region is 4 inches wide and the forward and rearward
end regions are 63/4 inches wide. The fibrous batt 15 is 13 inches
long, and is positioned in the center of the disposable diaper on
top of a wicking layer 16 having the same transverse and
longitudinal dimensions as the diaper. The diaper is double-pleat
folded as shown in FIGS. 2-4 along fold lines 38 and 40 which are 4
inches inwardly of the side margins of the diaper, and along fold
lines 36 and 42 which are 2 inches inwardly from the side margins
of the diaper. Accordingly, each of the panels of each of the
double-pleat folds is approximately 2 inches wide, and the central,
unfolded region of the diaper is approximately 4-1/2 inches
wide.
The diaper described in the preceding paragraph can include the
following weights of components: facing layer 12 -- 2 grams fibrous
batt 15 -- 25 grams wicking layer 16 -- 7-11 grams foam layer 18 --
5 grams backing sheet 20 -- 2 grams
Preferably the fibrous batt 15 of the absorbent core 14 is the
heaviest hydrophilic component of the diaper.
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