Note: Descriptions are shown in the official language in which they were submitted.
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DISPOSABLE DIAPER WITH FOLDED ABSORBENT BATT
.
Technical Field of the Invention
This invention relates to disposable
diapers. Gore particularly, this invention relates
to disposable diapers including a batt which is
constructed and arranged to provide increased
strength and absorptive capacity in the crotch region
of the diaper, while at the same time providing an
improved wicking mechanism for transporting liquid
away from an initially wetted area into remote
- regions of the batt.
Background of the Invention
Disposable diapers provide substantial
advantages and convenience over diapers intended to
be laundered and reused, and in recent years
disposable diapers have met with increased success in
the marketplace. Typical disposable diaper
structures include a moisture retaining layer of
relatively high liquid holding capacity sandwiched
between a moisture pervious facing layer to be
directed against the infant's skin, and a moisture
impervious plastic backing sheet to confine moisture
within the moisture retaining layer. Such diapers
are shown in U.S. Patent No. 3,612,055 to Mesek et
al. and in U.S. Patent No. Re: 26,151 to Duncan et al.
The moisture retaining layer of prior art
diapers have typically been comprised of a batt of
loosely compacted cellulosic fibers. It has been
known to provide such absorbent batts with an
integrally formed densified paper-like layer or skin,
and U.S. Patent Nos. 3,017,304 to Burgeni and
3,612,055 to Mesek et al. are typical of such
constructions. It is also known to provide absorbent
batts hazing a continuous dens~fied paper-like layer
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or skin with longitudinally extending thickened
densified regions for directing moisture in a
lengthwise direction of the batt, and Repke U.S.
Patent No 3,938,522 is typical of such constructions.
It is also known to provide disposable
diapers with reduced width crotch regions to reduce
the bulk and provide improved fit and comfort. Such
diapers are generally I-shaped, T-shaped or hour
glass-shaped, and U.S. Patent Nos. 3,559,648 to
Mason, Jr. and 3,768,479 to Widland are typical of
such constructions.
It is also known to provide absorbent batts
for disposable diapers with increased liquid holding
capacity in the central region of the batt, and
heretofore this has been done by providing an extra
batt layer (U.S. Patent No. 3,612,055), depositing
more absorbent material in the mid-portion of the
batt (U.S. Patent No. 3,938,522), or folding over the
side marginal edges of the batt (U.S. Patent No.
20 3,559,648). Such absorbent batts have had inadequate
inherent structural integrity, and have not provided
an adequate wicking mechanism for directing liquid
away from an initially wetted area.
It would be desirable to provide an
absorbent unit for a disposable diaper, or the like,
with increased liquid storage capacity in the central
region thereof, while providing a wicking layer
directly adjacent to the undersurface of the facing
layer in contact with the infant's skin for rapidly
directing liquid away from an initially wetted area.
It would also be desirable to provide such a batt
with a wicking mechanism whereby liquid spreading
outwardly would be directed downwardly into lower
portions of the batt remote from the layer in contact
with the infant's skin. It would also be desirable
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to provide the mid-portion of such a batt with a
strengthening means, so as to provide increased
structural integrity, particularly when the diaper is
to be worn for a prolonged period of time, such as
S overnight.
Summary of the Invention
The present invention provides an improved
absorbent unit for a-di~posable diaper or the like
wherein the body or central portion of the batt is
defined by multiple batt thicknesses for increased
liquid holding capacity. In accordance with one
aspect of the invention, the batt is provided with an
integrally formed, densified paper-like skin that is
positioned adjacent to the undersurface of the facing
layer that is to contact the infant's skin, so as to
provide a wicking mechanism for rapidly directing
liquid away from an initially wetted area for
absorption into remote regions of the batt. In
accordance with another aspect of the present
20 invention, a wicking mechanism extends downwardly
from the upper portion of the batt for directing
liquid downwardly toward the lower portion of the
batt. In accordance with still another aspect of the
present invention, a medial layer of the batt is
provided with an integrally formed densified
paper-like skin for increased strength and stability,
as well as for improved liquid transport.
The batt of the present invention may be
formed by cutting the longitudinal side edges of the
batt to define side flaps which may be folded
inwardly to provide multiple layers in the body or
central portion of the batt. In a preferred
embodimeDt of the invention the batt is cut about 1/3
of its width dimènsion so that the side flaps of the
batt and the medial section thereof are of generally
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equal dimension. With this arrangement, the side
flaps can be folded into overlapping relationship
with one another to provide an absorbent unit with
three layers in the central region thereof. The
desired wicking arrangement, and increased strength,
can be provided by forming such a batt with a
continuous densified paper-like skin, or layer, on
the undersurface thereof. It is most desired to
associate a batt of the above-described type with a
diaper product wherein the other diaper components
the facing and backing layers) are shaped, or
contoured, for improved fit about the perineal region
of an infant.
Brief Description of the Drawing
Figure 1 is a perspective view of a
disposable diaper formed in accordance with the
teachings of the present invention and laid out flat
in preparation for application to an infant;
Figure 2 is an exploded perspective view of
the disposable diaper of Figure 1, and illustrating
the batt in an intermediate step of formation;
Figure 3 is a perspective view of the diaper
of the present invention as applied to an infant; and
Figure 4 is an enlarged cross-sectional view
taken generally along line 4-4 of Figure 1.
Description of the Preferred Embodiment
While this invention it susceptible of
embodiment in many different forms, there is shown in
the drawing and will herein be described in detail a
preferred embodiment, with the understanding that the
present disclosure is to be considered as an
exemplification of the principles of the invention
and is not intended to limit the invention to the
embodiment illustrated. The scope of the invention
will be pointed out in the appended claims.
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Referring now to the drawings, the
disposable diaper 10 of the present invention
includes a facing layer 12 formed of a moisture
pervious material, and adapted to be positioned
adjacent to the infant's skin. Diaper 10 further
includes a moisture impervious outer layer 16
substantially coextensive in external dimension with
facing layer 12. Sandwiched between outer layers 12
and 16 is an absorbent unit 14 which is smaller in
external dimension than outer layers 12 and 16, and
which is disposed symmetrically with respect
thereto. Absorbent unit 14 may be secured to backing
sheet 16 by spaced, parallel glue lines, and layers
12 and 16 may be secured to one another outwardly of
batt 14 by such glue lines, as is well understood by
those skilled in the art.
Securement means is provided for releasably
attaching the diaper 10 about the perineal area of
the wearer, and such securement means may take the
20 form of tape tabs 18 secured to backing sheet 16 at
one end thereof, as is also well known to those
skilled in the art.
As can be best seen in Figure 1, batt 14 of
the present invention is generally I-shaped. 8att 14
includes relatively wide end portions 20 and 22
connected by a relatively narrow central portion 24.
Central portion 24 is adapted to be disposed in the
crotch area of the wearer, and includes a plurality
of thicknesses, or layers, to provide increased
absorptive capacity in the crotch region. With
reference to Figure 2, central portion 24 includes a
pair of side flap portions 26 at opposite sides of a
medial portion 28. Side flap portions 26 are defined
by lines of cutting 30 which extend inwardly from the
side marginal edges of batt 14, and in the
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illustrated embodiment, batt 14 is initially a
generally rectangular member, with cutting lines 30
being parallel to one another and to the end portions
of the batt. Batting lines 30 may be disposed at an
angle with respct to one another and with respect to
the side edges of the batt 14. Similarly, cutting
lines 30 could be secured, if desired. Cutting lines
30 extend about 1/3 of the width dimension of the
batt 14, so that side flaps 26 and medial portion 28
have substantially the same dimension. As is evident
by comparing Figures 2 and 4, batt 14 is given its
I-shaped configuration by folding side flaps 26
inwardly into overlapping relationship with one
another.
Several different types of facing materials
may be used, for example, the facing may be a
non-woven web made of a mixture of fibers consisting
predominantly of inexpensive, short, cellulosic
fibers such as short wood pulp fibers or cotton
linters in amounts of 75 percent to 98 percent, the
balance being textile length fibers such as rayon as
described in U.S. Pat. No. 3,663,348 to Liloia, et al.
Non-woven facing materials suitable for use
in disposable diapers of this invention can have
fabric weights in the range of from about 0.5 to 5
ounces per square yard and densities of less than
0.15 g/cc., generally in the range of 0.05 to about
0.1 g/cc. The dry strength of the facing sheet for a
fabric having a weight of about 1.5 ounces per square
yard is at least 0.15 lbs. per inch of width in the
machine direction and at least 0.1 lb. per inch of
width in the cross direction. Such fabrics have good
elongation, loft, softness, and drape
characteristics. Facings may also be made of an
apertured non-woven fabric which is formed, for
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example, in accordance with the teachings of commonly
assigned U.S. Pat. Nos. 2,862,251 3,0~1,514 and
3,081,S15. Furthermore, facings may also be made
from other types of fabric such as those disclosed
and described in U.S. Pat. No. 3,485,706 to Evans.
Such facings can be made of naturally occurring
fibers, synthetic fibers or blends thereof. Typical
facing sheets made of polyester type fibers may have
a weight of about 0.75 ounces per square yard.
In addition, facings may be made from
non-apertured materials such as non-woven isotropic
webs or apertured polyolefin or polyester films
having the desired moisture permeability. In all of
the aforementioned facings, the materials should be
relatively hydrophobic so as to retard wicking within
the facing.
A suitable backing material for the
disposable diapers embodying the present invention
can be an opaque polyolefin; for example,
- 20 polyethylene about 0.001 inch thick. Another
suitable material for this purpose is polyethylene
terphthalate having a thickness of about 0.005 inch.
The absorbent batt 14 preferably is formed
of loosely compacted short cellulose fibers, such as
wood pulp fibers, or cotton linters, or mixtures
thereof, which primarily are held together by
interfiber bonds reguiring little or no added
adhesive, as is known in the art. Briefly, these
batts are a low bulk density coherent web of loosely
compacted cellulose fibers, preferably comminuted
wood pulp fibers, in the form of so-called fluff.
he term short fibers as used herein,
refers to fibers less then about 1/4 inch in length,
in contrast to long fibers or textile length
fibers which are longer than about 1/4 inch in
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length, and generally are between about 1/2 and 2-1/2
inches in length.
Preferably the absorbent batt 14 includes a
paper-like, densified compacted cellulosic fibrous
layer 34 of relatively high wettability and
relatively high fluid retentivity integral with the
batt on the side thereof in contact with the backing
sheet 16. The paper-like densified layer 34 is
formed by slight moistening of one æurface of the
batt followed by the application of pressure
thereto. This densified skin portion provides a
wickabiiity gradient to draw urine from the more
loosely compacted cellulosic fibrous layer into the
densified layer. The densified layer portion is
described in more detail in Burgeni U.S. Patent No.
3,017,304.
The composite density of the absorbent batt
should be above about 0.07 gm/cc. and preferably
between about 0.10 and 0.15 gm~cc. The foregoing
density values are applicable to the diaper as
produced. In storage and handling, the loft or
thickness of the batt is increased to some extent,
resulting in lower densities.
Densified layer 34 preferably includes
regions of increased thickness dimension for adding
strength to the batt 14 and providing a further
wicking mechanism. The regions 36 of increased
thickness dimension are illustrated (Figure 4) as
parallel longitudinally extending thickened densified
lines. Such regions may be formed in accordance with
the teachings of U.S. Patent No. 3,938,522.
When the side flap sections 26 of a batt of
the type described above are folded into overlapping
relationship with one another, as is best seen in
Figure 4, a unique and highly advantageous batt
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structure is produced. In this regard, the central
portion 24 of the batt includes a first densified
layer 34a secured to backing sheet 16, a first
loosely compacted layer 28a above layer 34a, a second
loosely compacted layer 26a above layer 28a, a second
densified layer 34b above layer 26a, a third loosely
compacted layer 26b above densified layer 34b and a
third densified layer 34c adjacent to, and in contact
with, the undersurface of facing 12. Densified
bridging portions 34d and 34e connect densified
layers 34a and 34c, and 34a and 34b, respectively.
The densified layer 34 adds sufficient
stiffness to the panel 14 to make it practical to
form cutting lines 30 on a high speed production
basis, and also provides sufficient integrity to the
batt to enable the side flaps 26 to be folded into
overlapping relationship with one another. The
densified layers 34a, 34b and 34c, together with
thickened lines 36 integral therewith, provide a
- 20 wicking network for transmitting liquid rapidly
- toward unwetted remote portions of the batt.
Bridging portions 34d and 34e provide a mechanism for
directing liquid downwardly toward the lower portion
of the batt 14. Loosely compacted layers 26a, 26b
and 28a provide a reservoir for increased liquid
storage capacity in the central or crotch region of
the diaper.
In use, the disposable diaper is applied to
the baby by laying out the diaper on a single flat
surface and placing the baby thereon. The waist
underlying end of the diaper is that end having the
fastener means and the other end of the diaper
extends downwardly between the baby's legs. Next,
the downwardly extending edge of the diaper is
brought up between the bays legs to a position
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covering the perineum and contiguous with the front
portion of the baby's waist. The diaper thereafter
is secured to the baby by placing the corners of the
waist portion of the abdomen covering end as far
around the baby's waist as they will go and by
bringing the corners of the underlying end of the
diaper into an overlapping relationship with the
aforementioned corners so that the diaper snugly
encircles the baby's waist and provides a custom
fit. The adhesive tape fasteners are then prepared
for use and the diaper is secured in a desired
position by simply urging the pressure-sensitive
adhesive surface of the tape tab in contact with the
adjacent outer surfaces of the opposite corner of the
diaper.
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