U.S. patent number 3,863,637 [Application Number 05/313,595] was granted by the patent office on 1975-02-04 for folded disposable diaper.
This patent grant is currently assigned to International Paper Company. Invention is credited to Charles A. Lee, Richard C. MacDonald, Noel E. Martin.
United States Patent |
3,863,637 |
MacDonald , et al. |
February 4, 1975 |
FOLDED DISPOSABLE DIAPER
Abstract
A disposable diaper including an absorbent pad disposed between
a backing sheet which resists liquid flow therethrough and a liquid
pervious cover sheet. The diaper is folded, using longitudinal
folds, into a configuration which in cross section resembles the
Greek symbol sigma (.SIGMA.) on one side of the longitudinal
centerline of the diaper and a reverse sigma on the other side of
the diaper. The respective widths and lengths of the pad and
backing sheet provide for the fold in contact with the child to be
faced by the cover sheet so as to preclude the backing sheet in
this fold from contacting the child when the diaper is folded in
accordance with the present disclosure.
Inventors: |
MacDonald; Richard C. (Rexdale,
CA), Martin; Noel E. (Weston, Ontario, CA),
Lee; Charles A. (Knoxville, TN) |
Assignee: |
International Paper Company
(New York, NY)
|
Family
ID: |
23216350 |
Appl.
No.: |
05/313,595 |
Filed: |
December 8, 1972 |
Current U.S.
Class: |
604/365; 604/372;
604/370; 604/375; 604/385.201 |
Current CPC
Class: |
A61F
13/49426 (20130101); A61F 13/49466 (20130101); A61F
2013/5326 (20130101) |
Current International
Class: |
A61F
13/15 (20060101); A61f 013/16 () |
Field of
Search: |
;128/284,286,287,290,296 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pace; Channing L.
Attorney, Agent or Firm: Fitch, Even, Tabin &
Luedeka
Claims
What is claimed is:
1. In a disposable diaper having a rectangular outline and
including an absorbent pad encapsulated between a backing sheet
having an exposed surface and a liquid pervious cover sheet, the
improvement wherein said cover sheet is wider than said pad and
said backing sheet and defines longitudinal side extensions on
opposite sides of said diaper, each of said side extensions being
wrapped around the side edges of said pad and said backing sheet
and bonded to said exposed surface of said backing sheet at a
location spaced inwardly from the respective side edge of said
backing sheet, each side edge of said diaper being folded along a
longitudinal fold line inwardly toward the centerline of said
diaper to define a first longitudinal fold, further folded along a
second longitudinal fold line away from said centerline and back
upon said first fold to define a second longitudinal fold, and
further folded along a third longitudinal fold line inwardly toward
said centerline and back upon said second fold to define a third
longitudinal fold, whereby said side extensions of said cover sheet
are exposed on the respective outer surfaces of said third
longitudinal folds in position to cover that portion of said
backing sheet disposed in the upperside of said third folds and
thereby isolate said backing sheet from the skin of the person to
whom the diaper is applied.
2. The disposable diaper of claim 1 wherein said absorbent pad and
said backing sheet are substantially coextensive in width.
3. The disposable diaper of claim 1 wherein said absorbent pad is
shorter than said backing sheet and disposed substantially
centrally thereof to define end extensions of said backing
sheet.
4. The disposable diaper of claim 3 wherein said cover sheet is
substantially coextensive in length with said backing sheet whereby
said cover sheet overlies said backing sheet in the diaper ends to
provide lesser thickness of said diaper in the ends than in the
central portion thereof.
5. The disposable diaper of claim 1 and including liquid impervious
cross strips overlying a portion of each end of said absorbent pad
on the surface thereof facing away from said backing sheet and
extending from the respective ends of said pad and between said
backing sheet and said cover sheet, said backing sheet, cover sheet
and said cross strips at each end of said diaper being bonded
together along a bond line extending transversely of said diaper
adjacent each of said diaper ends to seal the diaper ends.
6. The disposable diaper of claim 5 wherein each of said strips is
wider than said pad but more narrow than said cover sheet whereby
the opposite side edges of each strip are wrapped around the side
edges of respective pad end to seal the side edges of said pad
end.
7. The disposable diaper of claim 1 wherein each of said side
extensions of said cover sheet is bonded to the exposed surface of
said backing sheet along a longitudinal bond line extending
substantially the entire length of said backing sheet.
8. The disposable diaper of claim 7 wherein said longitudinal bond
line is disposed inwardly toward the centerline of said diaper by a
distance which causes said bond line to be disposed on the
underside of said third longitudinal fold when said diaper is
folded.
9. The disposable diaper of claim 1 wherein said absorbent pad
includes a quantity of fluff, at least one tissue web covering at
least one surface of said fluff, and a plurality of spaced apart
bonds securing said fluff to said web.
10. The disposable diaper of claim 1 and including at least two
tack bonds maintaining the folds on either side of the diaper
substantially in their folded positions during use of the diaper,
one bond being between the base of the diaper and the underside of
the first fold, and one bond being between the upper side of the
second fold and the underside of the third fold.
11. The disposable diaper of claim 10 wherein said tack bonds join
only adjacent cover sheet portions in said folds.
12. The disposable diaper of claim 1 wherein said backing sheet
comprises a liquid impervious plastic material.
Description
This invention relates to disposable diapers, particularly diapers
of this type wherein the diaper is provided with longitudinal folds
on opposite sides thereof.
Disposable diapers have become a well known item in the
marketplace. Diapers including an absorptive material encapsulated
between a liquid pervious cover sheet which is adapted to be
disposed adjacent the body of the child, and a liquid impervious,
e.g., plastic, backing sheet disposed on that side of the pad away
from the child's body are shown in U.S. Pat. Nos. Re. 26,151,
issued Jan. 31, 1967 to Duncan et al.; 2,815,027, issued Dec. 3,
1957 to Makela; 2,896,626, issued July 28, 1959 to Voightman;
3,196,874, issued July 27, 1965 to Hreubecky; 3,572,342, issued
Mar. 23, 1971 to Lindquist et al.; and 3,520,303, issued July 14,
1970 to Endres. All of these prior disposable diapers have various
disadvantages.
It is an object of this invention to provide a disposable diaper
which obviates many of the disadvantages heretofore experienced in
a disposable diaper. It is also an object of this invention to
provide a disposable diaper having minimal leakage of exudate and
which provides the advantages of a plastic backed diaper but
wherein there is minimal plastic material in contact with the
child's skin. It is another object of this invention to provide a
disposable diaper which permits limited air circulation into and
out of the diaper between the child's legs and the diaper. Other
objects of this invention are: to provide a disposable diaper
having an enhanced profile and good fit when applied to a child; to
provide a disposable diaper which is readily packaged for sale; to
provide a disposable diaper wherein the cover sheet, the backing
sheet and the absorptive material therebetween are firmly retained
in their relative positions to reduce the opportunity for
misalignment of these elements in use; and to provide a folded
disposable diaper.
Various of the objects are accomplished by providing a disposable
diaper including an absorbent pad disposed between a backing sheet
which resists liquid flow therethrough and a liquid pervious cover
sheet and folding the diaper, using longitudinal folds, into a
configuration which in cross section resembles the Greek symbol
sigma (.SIGMA.) on one side of the longitudinal centerline of the
diaper and a reverse sigma on the opposite side of the diaper. The
pad and backing sheet are of substantially the same width with the
pad being shorter than the backing sheet. The cover sheet is of the
same length as, but is wider than, the backing sheet to provide
side portions which wrap the side edges of the pad and cover sheet
and which are bonded to the exposed surface of the backing sheet at
locations spaced inwardly from the side edges of the backing sheet.
When the diaper is folded in accordance with the present
disclosure, that fold in contact with the child is faced by the
cover sheet so as to preclude the backing sheet from contacting the
child, thereby eliminating a source of possible adverse reaction by
the child's skin and also eliminating the seal which develops
between the child's leg and the backing sheet when the latter
becomes moist or wet due to blocked perspiration or liquid exudate.
In the preferred diaper, that portion of the cover sheet covering
the upper surface of the backing sheet in the top fold is not
bonded to the backing sheet so that there is freedom for at least
limited relative movement between the backing sheet and the cover
sheet thereby permitting air circulation into and out of the diaper
in the leg and crotch region. In the approximate transverse
centerline of the folded diaper, the cover sheet is tacked to
itself in the folds providing good fit on a child and aiding in
holding the longitudinal folds in position to receive, distribute
and retain exudate. The ends of the diaper are strengthened and
sealed against leakage by folding the ends of the backing sheet
back over the pad ends or by providing plastic strips extending
transversely across the pad ends and sealing the strips to the
backing sheet. In one embodiment, migration of absorptive matter,
e.g., fluff, within the diaper is reduced by covering at least one
surface of the fluff with a web, such as a tissue sheet, and
bonding the two together by means of spaced-apart bond lines.
Adhesive tabs disposed on opposite corners of one end of the diaper
provide a means for securing the diaper on the child.
FIG. 1 is a schematic view of a folded diaper including various
features of the invention;
FIG. 2 is a schematic enlarged sectional view taken along the line
2--2 of the diaper shown in FIG. 1;
FIG. 3 is a schematic view of an unfolded, partly assembled diaper
incorporating various features of the invention; FIG. 4 is a
schematic view of an unfolded diaper including various features of
the invention;
FIG. 5 is a schematic enlarged fragmentary section taken along line
5--5 of FIG. 4;
FIG. 6 is a schematic section taken along line 6--6 of the diaper
shown in FIG. 4;
FIG. 7 is a schematic fragmentary view of an absorbent pad;
FIG. 8 is a schematic fragmentary view of a further absorbent pad;
and
FIG. 9 is a schematic fragmentary view of a folded diaper whose
ends have been opened as when applied to a child.
A disposable diaper 10 having a rectangular outline and including
an absorbent pad 12 encapsulated between a backing sheet 14 which
resists liquid flow therethrough and which has an outer exposed
surface 16, and a liquid pervious cover sheet 18 is depicted
schematically in the Figures. In the present disclosure, the
backing sheet is referred to as being of a plastic material but it
is recognized that the backing sheet functions to resist the flow
of liquid through the diaper and may be other than a plastic
material, for example a tissue sheet treated with a
water-repellant. As shown in FIGS. 1, 2 and 4, the disclosed diaper
is folded employing a sigma fold. In accordance with this folding
feature, each of the side edges of 20 and 22 of the flat diaper 10
(side edge 22 for example) is folded inwardly toward the
longitudinal centerline 24 of the diaper along a longitudinal fold
line A located inwardly from the respective side edge 22 of the
diaper by about 1/3 of the diaper width, to define a first
longitudinal fold 26. The side edge 22 of the diaper is further
folded outwardly from the diaper centerline along a second
longitudinal fold line B to define a second longitudinal fold 28
overlying the first fold 26. Still further, the diaper side edge 22
is folded inwardly in the same direction as the first fold along a
third longitudinal fold line C to define a third longitudinal fold
30 that overlies the second fold 28. Upon completion of this third
fold on each side of the diaper, the side edges 20 and 22 of the
pad and the side edges 32 and 34 of the backing sheet 14 are
disposed inwardly toward the centerline of the diaper, but the
cover sheet 18 extends over the top surface 36 of the third fold
30, wraps the pad and backing sheet at the location of the third
longitudinal fold line C, and terminates on the underside 38 of the
second fold 28.
In cross section, the central unfolded base 40 of the diaper and
the three folds 26, 28 and 30 on each side of the diaper resemble
the Greek symbol sigma (.SIGMA.), hence is referred to as a sigma
fold. (It will be recognized that the fold on one side of the
diaper will be the mirror image of the fold on the opposite side of
the diaper so that the fold on one side will be a "reverse"
.SIGMA..) This fold, in combination with the full width pad, offers
the advantage of having a portion of the absorptive pad disposed in
the top fold 30 so that as liquid is received in the central
portion 40 of the diaper and spreads laterally, there is
substantial absorbtive capacity in the folds, especially in the top
fold, to retain the fluid within the confines of the diaper and
prevent it from leaking out of the diaper in the leg regions.
Because the plastic backing sheet 14 fully covers the absorbent pad
12 in the top fold (as well as in the other folds) the absorbed
liquid is kept from striking through the pad in the crotch region
42 where there is normally a greater amount of flexing and working
of the diaper due to the child's leg movements. The exudate is thus
trapped within the diaper, keeping the child's skin and/or outer
clothing or bedding more free of the liquid exudate. Such trapping
of the exudate is enhanced in the disclosed diaper by two V-shaped
troughs 44 and 46 formed on each side of the diaper by the folds
(see FIG. 9). Both troughs, and particularly the first trough 44,
receive and disperse exudate in a direction longitudinally of the
diaper. The second of the troughs 46 further serves to assure the
containment for a time sufficient to permit absorption of any
exudate that moves past the first trough which is closest to the
central portion 40 of the pad.
The folds on each side of the diaper are secured in their folded
position at points located approximately on the transverse
centerline of the diaper, preferably by tack bonds 48 and 50. This
is accomplished by placing a small spot of adhesive between
selected folds as the folds are being formed. Hot melt adhesive of
the ethylene vinyl acetate type known commercially as No. 34-2938
and available from National Starch Company serves satisfactorily
for this purpose. This adhesive is not water soluble so that it
does not dissolve in the presence of fluid exudate, but rather the
spot bonds cause the diaper to retain its folded condition in the
crotch region 42 throughout its period of use.
It is acceptable to spot bond each of the folds to any other
contiguous fold in the crotch region. In the depicted diaper, tack
bonds are provided in the folds on each side of the diaper only
between the underside 52 of the first fold 26 and the central
portion 40 of the diaper, and between the underside 53 of the top
(third) fold 30 and the upperside 55 of the second fold. When the
diaper is applied to the child, these tack bonds keep these folds
together to insure good fit of the diaper in the crotch region but
permit the first and second folds to separate and provide expansion
of the diaper to conform to the child's legs. In a preferred tack
bond, only the facing portions of the cover sheet in the folds are
joined so that when the diaper is applied to the child, the cover
sheet 18 unfolds to a lesser extent than the absorbent pad 12 (see
FIG. 9) and effectively reduces the width of the diaper in the
crotch region 42 and provides a better fit on the child.
It will be recognized that the diaper is applied to a child in the
usual manner, that is, by fanning out one end 54 of the diaper,
laying the child on the opened end and bringing the opposite end 56
of the diaper up between the child's legs. This opposite end 56 is
also fanned out and the corners of the two ends joined to fasten
the diaper about the child's waist. In this operation, the folds
remain closed (folded) in the immediate region of the transverse
centerline of the diaper but gradually increasingly expand in the
direction away from the transverse centerline toward the ends of
the diaper. In the present diaper the layers of backing sheet,
cover sheet and absorbent pad present in each of the three folds on
each side of the diaper are maintained in their relative positions
within each fold and can be pulled tight about the child's legs
thereby imparting excellent conformability of the diaper to the
child in the leg region, hence a better fit on the child. This
feature is due also in part to the number of folds which increase
the expansibility of the diaper in a direction generally
perpendicularly to the diaper proper, so that as the ends of the
diaper are fanned open, such action does not place such stresses on
the diaper in the crotch region as cause it to buckle and fall away
from a good fit about a child's legs.
In the disclosed diaper, adhesive strips 58 and 60 are provided on
opposite corners 62 and 64 of one end 54 of the diaper with a
portion of each strip projecting from the side edge of each corner.
When the two ends of the diaper are in place about the child's
waist, these strips provide a means for releasably joining the
diaper ends together to secure it in position on the child in a
manner well known heretofore.
Referring particularly to FIGS. 7 and 8, the disclosed diaper 10
includes an absorbent pad 12 adapted to be disposed between the
cover sheet and the backing sheet. One suitable absorbent pad 12
comprises defiberized pulp referred to in the art as fluff 66. In a
common method of manufacturing the pad, the fluff 66 is deposited
on a tissue web or sheet 68 (FIG. 7) which is of substantially the
same width as the fluff and thereafter overlaid with a second
tissue 70 of equal width with the fluff to sandwich the fluff
between the two sheets of tissue. Alternatively, the fluff 66' may
be deposited on a sheet of tissue 68' (FIG. 8) which is
substantially wider than the fluff and the tissue sheet then
wrapped around the fluff to envelop it. For purposes of the present
discussion, the term "absorbent pad" is intended to include either
of these embodiments as well as other variations and combinations
of absorptive materials suitable for use in disposable diapers. One
such other material comprises multiple plies of creped wadding. The
fluff in the disclosed diaper is of uniform thickness across its
width. In certain applications, it has been found desirable to
provide additional thickness of fluff in the longitudinal center of
the pad to provide additional absorptive capacity in such region.
The pad in the disclosed diaper extends to the full width of the
unfolded diaper so that when the diaper is folded, there is
absorbent pad present in each of the folds including the top or
third fold 30 to insure absorption of liquid migrating to such
areas of the diaper.
The inventors have found that the integrity of the absorbent pad 12
of the present diaper is enhanced by tacking the tissue sheet 70
covering one of the surfaces of the fluff 66 to the fluff itself
using a plurality of spaced apart lines of adhesive 72. These lines
of adhesive are spaced apart by distances sufficient to prevent
them from adversely reducing the transfer of fluid exudate into the
fluff and so as not to stiffen the diaper. For example, adhesive
lines, each about one-sixteenth inch wide, spaced about 1 to 2
inches apart satisfactorily reduce the undersired fluff migration.
Generally parallel lines of adhesive extending longitudinally of
the pad function suitably for this purpose. Other arrangements of
the adhesive lines, such as a grid pattern, also provide acceptable
bonding between the fluff and the tissue sheet. Bonding of a single
surface of the fluff to a covering tissue sheet provides improved
integrity to the pad, but either or both of the fluff surfaces may
be bonded to covering tissue sheets to provide additional
integrity. These bond lines, even though the adhesive only
limitedly penetrates the fluff, have been found to reduce migration
of the fluff within the diaper and reduce accumulations of fluff
that are uncomfortable to the child and which reduce the
absorptivity of the diaper. Preferably the adhesive employed in the
bond lines is water-insoluble so that the integrity of the fluff is
retained when the diaper is wet. The adhesive may be applied
directly to the cover sheet or pad. One method for applying the
adhesive is to coat a thread, such as 50 denier nylon, with a hot
melt adhesive from a bath of liquid adhesive, partially solidify
the adhesive on the thread, position the thread between the cover
sheet and pad, and thereafter reactivate the adhesive with heat and
pressure to effect the desired seal. Other adhesives and methods
for their application will be recognized as suitable for bonding
the fluff to a covering sheet.
The absorbent pad 12 is overlaid on a liquid-flow resistive backing
sheet 14 such as a plastic film which preferably is embossed to
enhance its appearance and hand. The backing sheet 14 provides a
barrier against liquid flow through the thickness of the diaper and
is disposed on that side 74 of the absorbent pad 12 which is
intended to face away from the child when the diaper is applied. In
the present diaper, the backing sheet 14 is of the same width as
the absorbent pad 12 but longer than the pad by an amount
sufficient to provide end extensions 76 (only one shown) on
opposite ends of the diaper. That side of the backing sheet
opposite the side thereof which is in contact with the absorbent
pad 12 faces outwardly of the diaper when in use to define an
exposed surface 16. Films of various plastics provide acceptable
liquid impervious backing sheets. Polyethylene film, embossed with
a taffeta pattern, is particularly suitable because of its
appearance and availability at low cost. Films of about one mil
thickness provide sufficient strength when combined with a suitable
cover sheet to provide integrity to the diaper. Such relatively
thin films more closely resemble a cloth material so that the
diaper is pleasing in appearance and feel. These thinner films also
are flexible to the extent that the diaper is permitted to conform
to the contour of the child's body and provide a good fit on the
child. Films having a thickness of greater than about 3 mils are
excessively harsh, displeasing in appearance and more expensive so
that their use in the present diaper is not desired.
On that side of the absorbent pad 12 opposite the backing sheet 14,
there is overlaid a liquid pervious cover sheet 18. This cover
sheet is intended to contact the skin of the child when the diaper
is applied and to permit fluid exudate from the child to pass
therethrough to be absorbed by the underlying pad. Synthetic
nonwoven materials function satisfactorily to pass the fluid
exudate, aid in preventing escape of fluff fibers, and
simultaneously provide strength to maintain integrity of the
diaper. One particularly suitable nonwoven material comprises a web
formed from synthetic, hydrophobic fibers, such as rayon fibers
alone or mixed with wood fibers, that have been stabilized in web
form as by an adhesive which bonds adjacent fibers one to another.
Fiber lengths of about one-half inch formed into a web of about 5
mils thickness provide sufficient interfiber bonding to develop
good tensile strength in the web so that when the web is
incorporated with the plastic backing sheet to a disposable diaper,
the diaper resists tearing or other destructive forces such as are
present when the diaper is applied to an active child. Nonwoven
material comprising rayon fibers and known as Dryfil 300-205 and
available from the Nonwoven Products Division of International
Paper Company, N.Y. N.Y. has been successfully used as the cover
sheet in a disposable diaper having a 1-mil thick polyethylene
backing sheet. In webs about 5 mils thick and weighing about 0.624
ounces per square yard, this nonwoven material possesses a
toughness such that adjacent folds of the cover sheet can be tacked
to each other so that the diaper remains in its folded condition
when in use as referred to hereinbefore.
With reference to FIG. 3 showing the disclosed diaper in an
inverted position, the cover sheet 18 is of the same length as the
backing sheet 14 but is wider than the backing sheet and the
absorbent pad 12 to provide side extensions 78 and 80 on opposite
sides of the pad 12. In the present diaper, these extensions are
folded around the side edges 82 and 84 of the pad and the side
edges 32 and 34 of the backing sheet and bonded to the exposed
surface 16 of the backing sheet 14 as by longitudinal seams 86 and
88. The distance from the side edge of the backing sheet to a seam
is chosen so that when the diaper is folded as discussed
hereinbefore the cover sheet, and not the plastic backing sheet,
will be exposed on the upper surface of the top fold on each side
of the diaper as shown in FIG. 2. Among other things, this feature
of the disclosed diaper causes the relatively soft, porous cover
sheet of the folded diaper to be exposed on the upperside 36 of the
top fold 30 so that this cover sheet, and not the plastic, is in
contact with the child. In addition to the comfort afforded the
child, the porous cover sheet permits air flow into and out of the
diaper between the diaper and the child's legs. Importantly, as
depicted in FIG. 2, that portion 85 of the cover sheet 18 which
overlies the plastic backing sheet 14 on the upperside 36 of the
top fold 30 is not bonded to the backing sheet so that such cover
sheet portion 85 has limited freedom of movement with respect to
the underlying plastic backing sheet. By this means, these two
elements "work" relative to each other during movement of the
child's legs permitting the legs to "move" relative to the plastic
without being abraded or chaffed by the plastic. This relative
movement of the cover sheet and backing sheet on the upperside of
the top fold also aids in obtaining air circulation into the diaper
in the leg and crotch region.
Preferably, the location of each of the longitudinal seams 86 and
88 is spaced inwardly from the respective side edge of the diaper
by a distance sufficient to cause the seams to be hidden from view
on the underside of the second fold 28 of the sigma fold. Such
positioning of the seams in the folded diaper also locates them out
of contact with the child when the diaper is applied.
In bonding the side extensions of the cover sheet to the exposed
surface of the backing sheet, satisfactory retention of the
extensions in place has been obtained through the use of
longitudinal seams 86 and 88 of hot melt adhesive. Hot melt
adhesive of the ethylene vinyl acetate type, available commercially
from National Starch Company and identified as No. 34-2938, serves
satisfactorily in this function. Threads carrying hot melt adhesive
thereon as described hereinbefore provide satisfactory seals
between the cover sheet and backing sheet. Alternatively, when
either the backing sheet or the cover sheet, or both, is a
thermoplastic, the longitudinal seams may be made employing heat
and pressure. A single longitudinal seam has been found
satisfactory to bond the cover sheet to the backing sheet but in
some applications it may be desirable to employ two or more such
seams.
As best seen in FIGS. 3 and 5, in the disclosed diaper each of the
ends 90 (only one end shown) of the absorbent pad 12 is covered by
a plastic cross strip 94. Each cross strip preferably is of a
liquid impervious material such as a plastic, e.g., polyethylene of
about 2 mil thickness, and extends from the end of the pad to be
received between the backing sheet 14 and the cover sheet 18. Each
of the ends of the diaper is sealed as by applying heat and
pressure to the cover sheet, backing sheet and cross strip
therebetween to bond these members to each other across the width
of the diaper. In the disclosed diaper, the bond comprises
heat-sealed seams 96 and 98 which join the plastic cross strip 94
to the plastic backing sheet 14 to form a liquid impervious seal
therebetween and secure the plastic cross strip in position to
provide reinforcement in the diaper ends for fastening the diaper
about the child's waist and to provide a barrier against leakage of
fluid exudate from the ends of the diaper. The use of plastic end
barriers in disposable diapers is disclosed in U.S. Pat. No.
3,572,342 issued Mar. 23, 1971 to Lindquist et. al. where the ends
of the plastic backing sheet are folded over the ends of the pad to
form a type of waterproof pouch for the pad. In U.S. Pat. No.
3,629,039, issued Dec. 21, 1971 to Frick, the pouch is formed of
two members, i.e., the backing sheet and strips of plastic, that
are sealed together to serve the same purpose of providing a
water-tight pouch for the pad. In the disclosed diaper, the plastic
strips are wider than the absorbent pad so that they are folded
around the side edges of the pad ends with the cover sheet as
referred to above. In this manner, a more complete liquid barrier
is formed at each end of the diaper and leakage is reduced at the
corners of the diaper where pinning or taping occurs and dryness is
desired for assuring that the diaper stays fastened on the
child.
A diaper of the kind disclosed herein and useful for "daytime" use
on infants typically is approximately 18 inches long and 13 inches
wide. The absorbent pad of this diaper includes about 19 1/4 grams
of fluff and about 6 1/2 grams of tissue web covering the fluff on
its opposite sides. In this diaper the pad is about 2 inches
shorter than the backing sheet and centered on the backing sheet so
that the ends of the backing sheet extend about one inch beyond the
pad at each end. Each end of the pad is covered by a plastic, e.g.,
polyethylene, strip that extends preferably fully across the width
of the pad 12 and beyond each of the side edges 82 and 84 of the
pad and the side edges 32 and 34 of the backing sheet by about one
inch on each side of the pad. This strip also extends from the ends
91 and 93 of the backing sheet 14 and the cover sheet 18,
respectively, in the direction of the diaper length by a distance
of about 2 1/2 inches so that about 1 1/2 inches of the length of
the pad at its end 90 is overlaid by the strip 94 on that surface
of the pad which faces the cover sheet 18. When the strip at each
end of the diaper is bonded to the backing sheet as referred to
above, the backing sheet and strip form a waterproof pocket or
receptacle 95 for the absorptive pad. Accordingly, leakage of fluid
exudate from either the sides or ends of the diaper is avoided by
this barrier.
The cover sheet for the "daytime" diaper is of the same length as
the backing sheet but is about 4 inches wider so as to provide a
2-inch wide extension of the cover sheet on each side of the diaper
that is folded around the respective side edges of the pad and
backing sheet inwardly toward the centerline of the diaper where it
is bonded to the exposed surface of the backing sheet.
In folding this diaper, about 4 1/2 inches of a side edge thereof
is folded inwardly along a first longitudinal fold line. About
three inches of this side edge is folded back upon the first fold
to develop about 1 1/2 inches width in the first fold. The side
edge is further folded back upon the second fold to cause the
second and third folds to each have a width of about 1 1/2 inches.
In this manner, the longitudinal seam 88 that bonds the side
extension 80 of the cover sheet 18 to the exposed surface 16 of the
backing sheet 14 is not exposed as a result of the folding, but
rather, in the folded diaper, the seam is disposed on the underside
of the second fold 28. This places the seam out of sight and,
importantly, positions it so that it does not contact the child's
skin and present a source of irritation to the child.
Alternatively, the folding is carried out so that the top or third
fold is more narrow than the second fold. In any event, the folds
enhance the fit of the diaper on the child and provide an efficient
and comfortable item of clothing. It will be recognized that the
sigma fold employed in the disclosed diaper permits a diaper of
given width to be folded into a more narrow diaper than is possible
using prior art folding techniques. The present diaper, therefore,
provides a quantity of absorptive material equal to prior diapers,
but in a more narrow diaper that better fits between a child's
legs.
While a preferred embodiment has been shown and described, it will
be understood that there is no intent to limit the invention by
such disclosure but, rather, it is intended to cover all
modifications and alternate constructions falling within the spirit
and scope of the invention as defined in the appended claims.
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