U.S. patent number 3,779,246 [Application Number 05/187,473] was granted by the patent office on 1973-12-18 for disposable diaper.
This patent grant is currently assigned to Johnson & Johnson. Invention is credited to Frederick K. Mesek, Virginia L. Repke.
United States Patent |
3,779,246 |
Mesek , et al. |
December 18, 1973 |
DISPOSABLE DIAPER
Abstract
A disposable multi-layer diaper of high absorptive capacity is
provided which comprises as a first layer, to be brought into
contact with an infant's skin, a porous, fibrous, non-woven bonded
facing web of controlled wettability made of mixed long and short
fibers. A second layer, in juxtaposition to the facing layer, is a
highly porous, loosely compacted cellulosic batt having greater
wettability than that of the facing web. Beyond the cellulosic batt
is an impervious backing sheet adhered to the batt over a widely
distributed area of adhesion. The final or outermost layer is a
fibrous material which is adhered to the backing sheet, and which
enables the diaper to have the feel and handle of a cloth diaper.
The outermost layer, preferably, is a non-woven web made of mixed
long and short fibers that are bonded together with a
water-repellent bonding agent.
Inventors: |
Mesek; Frederick K. (Downers
Grove, IL), Repke; Virginia L. (Oak Forest, IL) |
Assignee: |
Johnson & Johnson (New
Brunswick, NJ)
|
Family
ID: |
22689142 |
Appl.
No.: |
05/187,473 |
Filed: |
October 7, 1971 |
Current U.S.
Class: |
604/365; 604/366;
604/370; 604/375; 604/378 |
Current CPC
Class: |
A61F
13/5148 (20130101); A61F 2013/1543 (20130101) |
Current International
Class: |
A61F
13/15 (20060101); A41b 013/02 () |
Field of
Search: |
;128/284,287,290,296 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rosenbaum; Charles F.
Claims
What is claimed is:
1. A multi-layer diaper comprising: a rectangular facing layer
adapted to be positioned adjacent the skin of an infant during use,
said facing layer being a lofty and soft nonwoven fabric having a
density of less than 1.15 gm./cc. and comprised of mixed long and
short fibers; a highly porous, loosely compacted, cellulosic
fibrous batt in face-to-face juxtaposition to said facing layer and
having a greater wettability to water than said facing layer, the
face of said batt opposite said facing layer having a paper-like,
densified compacted cellulosic fibrous layer of relatively high
wettability and relatively high fluid retentivity formed integrally
with said batt, said batt being rectangular, narrower than said
facing layer and centrally disposed with respect thereto; a water
impervious sheet on the side of said batt opposite said facing
layer, said sheet being rectangular, coterminous with said facing
layer, and adhered to said batt and to the marginal portions of
said facing layer outwardly of said batt; and a rectangular outer
layer on the side of said sheet opposite said batt, said outer
layer being coterminous with said sheet and secured thereto, said
outer layer being a lofty and soft nonwoven fabric having a density
of less than 0.15 gm./cc. and comprised of mixed long and short
fibers.
2. The diaper of claim 1 wherein said outer layer is
hydrophobic.
3. The diaper of claim 2 wherein said outer layer is through bonded
with an acrylic latex binder.
4. The diaper of claim 2 wherein said outer layer has a weight
between about 1/2 oz./yd..sup.2 and about 2 oz./yd..sup.2
5. The diaper of claim 2 wherein said outer layer is adhesively
secured to said sheet.
6. The diaper of claim 2 wherein said sheet is formed of a
thermoplastic material and said outer layer is heat sealed to said
sheet.
Description
BACKGROUND OF THE INVENTION
Disposable diapers provide substantial advantages in convenience
over diapers intended to be laundered and re-used, particularly
when they are used away from home. In recent years, many different
disposable diapers have been proposed and some have been successful
in the marketplace. However, even the successful diapers are
inadequate in funcitoning properties and appearance, and their
success has come because consumers are resigned to accepting
inadequate performance and less than satisfactory feel and
appearance, as part of the price for convenience.
A common form of disposable diaper comprises a facing layer, an
absorbent layer and a moisture-impervious backing material, such as
a polyethylene film, the facing layer being innermost and the
backing material outermost when the diaper is worn. One of the
obstacles that manufacturers of such diapers must overcome is that
a certain number of mothers object to the feel and handle of the
diaper, and particularly object to the feel of the polyethylene
film. Even though improved diaper structures, such as those
disclosed in U.S. Pat. No. 3,612,055, dated Oct. 12, 1971, minimize
and effectively eliminate contact between the backing sheet and the
infant's skin, many mothers remain convinced that plastic materials
are not comfortable to an infant, and hence are reluctant to even
try, let alone use, disposable diapers that include an exposed
plastic backing sheet. To meet this concern, single use diaper
manufacturers have devoted substantial time and effort to improve
the feel and appearance of their products.
A solution to the above problem that has been proposed is to
completely eliminate the backing member, and replace it with a
woven or non-woven fabric that has been treated to be water
repellent. However, it has been found that it has not been possible
to make a fibrous web sufficiently water repellet to hold a
voluminous quantity of liquid within the diaper, without
sacrificing the sought after soft feel. Because such webs of
necessity have limited water repellency, it has been conventional
to also use an auxiliary outer garment, such as moisture-proof
pants, particularly at night when several voidings might occur.
Another solution to the above problem that has been proposed is to
deeply emboss the polyethylene backing sheet to improve its drape
and feel. A diaper with a deeply embossed backing sheet has
substantially improved drape and feel characteristics over a diaper
wherein the backing sheet is not embossed, or even lightly
embossed, but such a backing sheet is still relatively slippery and
difficult to grasp, particularly when moistened. Furthermore, while
a deeply embossed polyethylene backing sheet has functional
advantages, it has practical disadvantages, since special
manufacturing techniques are required, which adds to the cost of
the diaper.
It has also been proposed to improve the feel of a plastic backing
sheet by adding a plasticizer to the plastic material. While this
expedient has given the backing sheet a softer feel, it also
reduces the structural integrity of the sheet and increases the
possibility that the backing sheet might be punctured even during
normal handling.
SUMMARY OF THE INVENTION
In accordance with the present invention, an improved diaper is
provided which, in its optimum embodiment, has all of the
advantages of the diaper disclosed in our above-mentioned patent,
while at the same time having the added advantage that the
impervious polyethylene backing sheet is disposed within the
interior of the diaper, as a result of the provision of a fibrous
outer layer adhered to the backing sheet. The resulting diaper not
only has a pleasant external feel, but also enables a thinner
gauge, less costly material to be used for the backing sheet,
thereby making the diaper less stiff and more conformable.
Furthermore, since the moisture-impervious layer is disposed within
the diaper, other cost savings are realized, since it is no longer
necessary to add pigmentation to the polyethylene or to deeply
emobss the same.
An additional advantage is that the fibrous outer layer increases
the stability and functionality of the diaper. In this regard, the
fibrous outer layer provides increased frictional resistance and
greater resistance to slippage, which facilitates the handling and
manipulation of the diaper when it is initially applied, and which,
because of the increased purchase, minimizes the possibility that a
carried infant might be dropped. In a preferred embodiment, where
the outer layer is a self-sustaining fabric that is bonded to the
impervious backing member, the overall strength and dimensional
stability of the diaper is significantly improved. The outer layer
is coextensive with the backing sheet and the facing layer to
provide increased pinning strength at the marginal portion of the
diaper. Because of the increased strength, plasticizers can be
added to the plastic material from which the backing sheet is made
to increase the pliability and conformability of the composite
diaper structure.
The outer fibrous layer is also preferably hydrophobic in nature,
so as to repel any liquid that might wick around the edges of the
backing sheet when the diaper becomes saturated, or which might
tend to escape from a pin hole or other aperture in the backing
sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the invention, reference will
now be made to the accompanying drawings wherein:
FIG. 1 is a perspective view, with certain portions broken away for
clarity, of an open unfolded diaper in accordance with one
embodiment of the invention;
FIG. 2 is a partial cross section of the diaper of FIG. 1 taken on
the line 2--2, illustrating the internal configuration of the
embodiment of FIG. 1;
FIGS. 3 and 4 are partial cross sections similar to FIG. 2,
illustrating alternate embodiments of the invention;
FIG. 5 is a perspective view on a reduced scale of the diaper of
FIGS. 1 and 2 in its configuration after being put on an
infant;
FIG. 6 is a perspective view, partially in phantom, illustrating
one manner in which the diaper of FIGS. 1 and 2 may be folded and
the manner of partially opening the diaper for use;
FIG. 7 is an enlarged fragmentary cross section illustrating a
preferred absorbent assembly;
FIG. 8 is a simplified schematic view of a production line
illustrating the manner in which the diaper is made;
FIG. 9 is a further simplified schematic view of a modified
production line illustrating another manner in which the diaper can
be made;
FIG. 10 is an enlarged sectional view of the split web that is
formed by the process of FIG. 9;
FIG. 11 is a fragmentary perspective view of one portion of the
split web of FIG. 10; and
FIG. 12 is a sectional view, on a reduced scale, of an alternate
embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings, and particularly to FIGS. 1 and 2,
diaper assembly 10, when fully opened and laid out flat, comprises,
in order, fibrous facing layer 16 adapted to be positioned adjacent
the skin of an infant, absorbent fibrous pad, or batt 14,
water-impervious sheet 12, and final or outermost layer 13 of
fibrous material. Fibrous layers 13 and 16 are rectangular in
shape, equal in dimension, and coterminous with backing sheet 12.
Batt 14 is also rectangular in shape, but smaller than sheet 12 and
layer 16, and disposed centrally thereof. The marginal portions 12b
and 16b (i.e., the portions extending beyond batt 14) of sheet 12
and facing layer 16, respectively, are in face-to-face engagement
with one another, and outermost layer 13 is in face-to-face
engagement with sheet 12 throughout the interface therebetween.
Batt 14, preferably although not necessarily, has a paper-like
densified, highly compacted lowermost fibrous layer 18 which is
adhered to sheet 12 by bead lines of adhesive 22 (FIGS. 1 and 7)
substantially throughout the interface therebetween. Marginal
portions 12b and 16b are also adhered to each other by bead lines
22, and this mode of securement may also be used to adhere
outermost layer 13 to sheet 12.
Sheet 12 is formed of a flexible, moisture-impervious material,
preferably thermoplastic, and since sheet 12 is enclosed within the
interior of the diaper, it may be formed of a thinner gauge
material than is necessary in other constructions when the sheet is
relied upon as the main component to provide strength and stability
to a diaper. The thickness of sheet 12 may vary from about 0.00025
to 0.003 inch and the preferred material is polyethylene which may
be utilized with a thickness as small as 0.00075 inch, although a
thickness of 0.001 inch is also satisfactory. Sheet 12 may be
embossed to increase its flexibility and conformability, although
with thinner gauge materials embossing is not necessary. Other
suitable flexible moisture-impervious sheets may be used in
accordance with the invention, such as, for example, polyvinyl
chloride or polyethylene terephthalate sheets having a thickness of
about 0.0005 inch, for example. Since the moisture-impervious sheet
is disposed within the interior of the diaper, it is not necessary
to add pigmentation to the plastic material. Furthermore,
plasticizers may be added to increase the flexibility and
conformability of sheet 12.
Batt 14 is formed of loosely compacted short cellulose fibers, such
as wood pulp fibers, or cotton linters, or mixtures thereof, which
are primarily held together by interfiber bonds requiring no added
adhesive, as is known in the art. Briefly, this batt is a low bulk
density coherent web of loosely compacted cellulose fibers,
preferably comminuted wood pulp fibers in the form of so-called
"fluff".
The term "short fibers," as used herein, refers to fibers less than
about one-fourth inch in length, in contrast to "long fibers," or
"textile length fibers," which are longer than about one-fourth
inch in length, and generally are between about 1/2 and 21/2 inches
in length. The former are substantially less costly than the
latter. The classification of fibers by length may be carried out
by the Clark Classification procedure described in the test manual
of The Technical Association of Pulp and Paper Industry (TAPPI-T233
SU64).
Paper-like densified layer 18 of batt 14 is formed by a slight
moistening of one surface of the batt followed by the application
of pressure thereto. The nature of the batt and of its densified
layer and the method of producing the same are described in U.S.
Pat. No. 3,017,304, dated Jan. 16, 1962.
The composite density of batt 14, including its densified layer 18,
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
lowered densities.
Facing layer 16 is made up of a mixture of fibers consisting
predominantly of short cellulosic fibers such as wood pulp fibers
or cotton linters, in amounts of about 75 percent to about 98
percent, the balance being textile length fibers such as rayon.
Short cellulosic fibers such as wood pulp fibers or cotton linters
are substantially less expensive than textile length cellulosic
fibers such as cotton and rayon, and this low cost is a factor in
reducing the cost of the facing layer component of the diaper of
this invention.
In facing layer 16, the short fibers are in uniform admixture with
2 percent to 25 percent by weight of textile length fibers, such as
1.5 denier rayon fibers uniformly cut to 11/2 inches length. The
short and long fibers are randomly and substantially uniformly
dispersed and bonded with a bonding agent such as a
self-cross-linking acrylic emulsion. One bonding agent that has
been applied with considerable success is a latex of a
polyethyl-acrylate copolymer containing small amounts of
acrylonitrile and a cross-linking monomer sold under the trademark
HYCAR 2600 .times. 120. The bonding agent should be of the low
viscosity type with a viscosity less than 5 centipoises. The facing
web is also treated with a wetting agent, preferably an anionic
surfactant, to partially counteract the water repellency of the
bonding agent and bring the facing layer to the desired degree of
wettability. A typical surfactant which has been found to be
suitable is the ionic sulfonated alkyl ester sold under the
trademark TRITON GR-5. Facing layers of this character are
described in greater detail in commonly-owned copending U.S. Pat.
No. 3,663,348, dated May 16, 1972.
Facing layers suitable for use in this invention have fabric
weights in the range of 1 to 5 oz./yd..sup.2 and densities less
than 0.15 gm./cc., generally in the range between 0.05 and 0.1
gm./cc. The dry strength of the facing layer, for a fabric having a
weight of about 1.5 oz./yd..sup.2, is at least 0.15 lbs./in. of
width in the machine direction and at least 0.08 lbs./in. of width
in the cross direction. The fabrics have unusually good elongation,
loft, softness and drape characteristics in comparison to prior
products incorporating any substantial amount of short fibers.
For a more detailed description of batt 14 and facing 16 as well as
the methods of producing them, reference may be made to the above
mentioned U.S. Pat. No. 3,612,055, the disclosure of which is
hereby incorporatd herein in its entirety by this reference.
Outermost layer 13 is preferably identical to facing layer 16
insofar as fiber mixtures and proportions are concerned, although
layer 13 differs from layer 16 in certain other important respects.
For example, it is desirable that layer 13 be water repellent to
prevent liquid from wicking around sheet 12 when the batt 14
becomes saturated, and to prevent liquid from striking through the
diaper as a result of a pin hole or other aperture. To this end,
the wetting agent is omitted from the bonding solution for layer
13, and as a result the bonding agent renders outer fibrous layer
13 hydrophobic. Thus, the outer layer tends to reject fluid and
reamin dry. The improved feel, handle and water repellency
characteristics of layer 13 are, to a large extent, independent of
the thickness of the layer, and thus layer 13 may be substantially
thinner than layer 16, if desired.
The weight of layer 13 is also preferably less than the weight of
facing 16, for sake of economy, the optimum range being about 1/2
oz./yd..sup.2 to about 2 oz./yd..sup.2 Furthermore, in its broadest
aspects, the present invention is not limited to any specific type
of fibrous material for layer 13, and this layer can be formed of a
woven or non-woven fabric, and in the event of a non-woven fabric,
the same may be wet or dry formed. In fact, certain of the
advantages of the present invention, i.e., the improved feel and
appearance of the diaper, can be obtained by forming outermost
layer 13 of flocked fibers or tissue. This alternative can be
resorted to when the strength of a self-supporting web is not
required, for example, when a polyethylene sheet 0.001 inches thick
is used as moisture-impervious sheet 12.
As is explained in detail in our above mentioned U.S. Pat. No.
3,612,055, an important aspect of the improved diaper is the
provision for selective wettability among the above described
fibrous components, such that the moisture is selectively drawn
from the facing layer into the body of the batt and then from the
body of the batt into the densified layer thereof. Specifically,
when liquid, such as urine, flows into a small area on the outer
surface of facing layer 16, it flows preferentially into underlying
batt 14 rather than to other areas of the facing layer, thus
tending to restrict wetting in the facing layer to a small area and
to move the liquid away from the infant's skin. The liquid flowing
into a small area of loosely compacted batt 14 flows preferentially
into underlying densified layer 18, rather than to other areas of
the batt, thus tending to restrict wetting in the batt to an area
of moderate size and to move the liquid farther from the infant's
skin. The liquid flowing into densified layer 18 tends to spread
laterally because of its wicking action, and liquid which might
pass through the densified layer during discharge (when flow is
rapid) is held back by the impervious backing sheet for sufficient
time to permit absorption to take place. Liquid in excess of the
absorptive capacity of densified layer 18 is forced back by
impervious layer 12 into the dry portion of loosely compacted batt
14, thus utilizing the additional absorptive capacity therein. Any
liquid tending to wick around the edges of impervious sheet 12 when
the diaper is saturated, or tending to escape through an aperture
in sheet 12, is repelled by the hydrophobicity of outermost layer
13. Thus, layer 13 cooperates with impervious sheet 12 to hold the
urine within the diaper and keep it from wetting the bed clothes or
outer clothing. In addition, since layer 13 is adhered to the
impervious sheet over a widely distributed area, layer 13
strengthens the diaper by reinforcing impervious sheet 12.
While layer 13 has heretofore been described as being adhesively
secured to impervious sheet 12, it should be understood that the
invention is not limited to any particular mode of securement,
since the layer could also be secured to sheet 12 in other manners,
such as by heat sealing. If a heat sealing process is used, outer
layer 13 may be bonded to sheet 12 in selected areas, as around the
outer margin of the diaper, or along lines similar to lines of
adhesive 22.
The embodiment of FIGS. 1 and 2, described above, is one of the
simplest and most economical forms of the present invention. For
superior performance, however, the embodiment of FIG. 3 is
preferred. The construction of FIG. 3 is similar to that of FIG. 2,
except that facing layer 16 is cut wider than the impervious sheet
and is folded under on itself in the marginal portions to provide a
thicker and heavier border. The underfolded portion of the facing
layer is shown as 16c and the bight as 16d.
Since facing layer 16 has substantial body and strength, folding it
over at the marginal portions of the diaper enhances the strength
of the diaper and provides additional tear resistance where pins
are used. In addition, the configuration of FIG. 3 improves the
balance and feed of the diaper and provides better sealing where
the edge portions come into contact with the thighs of the infant
when the diaper is secured in place.
Another advantage of the FIG. 3 embodiment is derived from the fact
that the folding over of the facing layer compresses it at the
inner surface of the fold and stretches it at the outer surface of
the bend to produce a lower density at the outermost edge of the
folded facing layer. When the diaper is thoroughly saturated with
urine to the edges of the facing layer, the urine will tend to be
held in the densified inner portion of the fold in preference to
the less dense outermost edge and will thereby tend to be held
within the diaper.
While the diaper described above has been characterized as
including a specific type of facing layer and a specific type of
batt, it should be understood that in its broadest aspects the
present invention is not limited thereto, and specifically
different types of facings and/or batts are within the purview of
the present invention. For example, the facing could be formed by a
tissue sheet-creped or uncreped, a suitable foam material or a
woven sheet. Also, the batt could be formed or creped wadding or
tissue.
In the embodiment of FIG. 4, there are two batts disposed between
facing layer 16 and impervious sheet 12, batt 14' and a second,
larger batt 20. The overall effect is to provide a stepped cross
section as shown in FiG. 4. While neither of batts 14' or 20 has
been illustrated as having a densified layer, as shown at 18 in
FIGS. 1-3, it should be understood that a densified layer could be
provided on either or both of these batts, and our invention is to
be construed as including a densified layer, where desired.
When an infant's weight rests on the stepped construction of FIG.
4, there is a tendency for the uncompressed absorbent material of
batts 14' and 20 to become partially compressed by the weight.
Since there is a greater thickness of material in the center of the
stepped construction of FIG. 4 than at the margins, there will be
greater pressure (and hence more compression) at the center. This
results in a smaller effective capillary radius in the center
section and greater wickability of the more highly compressed
center portion as compared to the less compressed marginal
portions.
In the case of a night diaper designed to hold several voidings,
the construction of FIG. 4 helps to keep the urine in place in the
central portion of the diaper and away from the edges from which it
might leak out.
The diaper of this invention is normally packaged and sold in a
folded condition. FIG. 6 illustrates the diaper of FIG. 1 in a
folded state and also illustrates, in phantom, the diaper in a
partially opened state, ready for application onto the lower torso
and thighs of an infant.
As shown in FIG. 6, side margins 12b and 16b of impervious sheet 12
and facing fabric 16, respectively, together with a portion of batt
14, are folded inwardly in a first fold to provide as the uppermost
layer of the fold, a portion of the moisture-impervious sheet. This
sub-assembly is then folded outwardly about its midportion in a
second fold to cover the first folded portion and to expose edge
portion 16e of the facing fabric as the upper layer of the double
fold. In the preferred embodiment, each double fold at the edge of
the diaper comprises approximately one-third of the resulting
transverse dimension of the folded diaper, leaving approximately
one-third of the width of the folded diaper as a central unfolded
and uncovered portion.
The diaper is held in its folded condition, for example, by two
small central spots of adhesive 24 applied between the main body of
the diaper and overlying sides 16b of the facing layer, one spot on
each folded side of the diaper.
When the diaper is to be put on the infant, the folds are opened on
one side of each of the adhesive spots, as shown in phantom in FIG.
6, and the open portion of the diaper is put under the infant's
buttocks while the folded portion between adhesive spots 24 is
raised into the crotch region. The final form of the diaper is
shown on a reduced scale in FIG. 5, and as illustrated therein, end
portions 10b and 10c of the diaper are folded upwardly to define a
waistband, and the corner portions 10e - 10h of the diaper are
folded outwardly toward the position illustrated in phantom in FIG.
6 at 10d, so that corner 10e approximately mates with corner 10b on
one side of the infant's waist, while corner 10g mates with the
corner 10h on the opposite side of the infant.
In one form of the invention, as illustrated in FIGS. 5 and 6, the
diaper is provided with adhesive tabs 26, each having a fixed end
secured to outermost layer 13 and a free end 30 wherein the
adhesive surface is covered with a facing sheet 32. Facing sheets
32 are removed to expose the adhesive surfaces when the diaper is
applied to the infant, as in the configuration shown in FIG. 5, and
free ends 30 of the adhesive tabs are secured to the opposite
corners of the diaper.
FIG. 8 discloses an exemplary type of production line, in schematic
form, that may be utilized to produce the previously described
diaper structures. As shown therein, roll 36 of suitable backing
sheet material is provided to feed continuous sheet 12 between
adhesive supplies 38 and 39, which apply adhesive to opposite sides
of the sheet 12. The adhesive may be sprayed or rolled in lines
along the length of sheet 12, or if desired, a weir arrangement or
print rollers can be employed to distribute the adhesive in any
desired pattern.
Roll 40 of batt material is provided downstream of adhesive supply
38, and feeds batt sections 14 onto adhesively treated sheet 12. A
cutter (not shown) may be provided adjacent roll 40 to sever the
batt material into appropriate lengths, or alternatively, roll 40
may be driven intermittently, and because of the minimal
longitudinal strength of the batt material, the batts will be
automatically severed into the desired length.
Roll 42 of facing fabric material is provided above sheet 12
downstream of roll 40, and roll 42 is driven continuously to lay
the facing layer 16 over the sheet 12 and batts 14. In a similar
manner, a supply of material for outer layer 13 is provided on roll
43 beneath sheet 12 and downstream of adhesive supply 39, and roll
43 is driven continuously to apply outer layer 13 against the
undersurface of sheet 12.
A pair of vertically aligned pressure rollers 44, 46 squeeze batts
14, outer layer 13 and the facing 16 against the adhesively coated
sheet 12, to insure that all of the elements of the diaper will be
positively held in place. A cutting roller 48 downstream of
pressure rollers 44, 46 severs the chain into individual diapers,
either before or after the diapers have been folded into the
configuration shown in FIG. 6.
Referring now to FIG. 9, a further form of production line for
producing the previously described diaper embodiments is
illustrated therein. The facing and outer layers of the diaper are
formed from a composite fibrous sheet 90, which is preferably made
in the manner described in U.S. Pat. No. 3,483,051. Briefly,
individual fibrous webs of mixed short and long fibers, as
described above, are air-laid on separate machines, with a majority
of the fibers of each web being arranged in shingle-like fashion.
The webs are plied together with the fibers of each web being
disposed at oppositely inclined acute angles with respect to the
interface between the webs. The resulting composite is then through
bonded with a stabilizing agent, and led to a supply roll, such as
shown at 92. The composite sheet 90 is fed from roll 92 between
rolls 94 and 96 with the common vertex between the aforesaid acute
angles facing to the right as viewed in FIG. 9, and as fabric 90
leaves rolls 94 and 96, it is separated generally along the
interface between the two starting webs into two separate fabrics
98 and 108. Fabric 90 can be separated into two substantially equal
layers 98 and 108; however, if desired, the manufacturing steps can
be controlled to provide layers which have different
weights-per-unit area, different densities, and different
thicknesses. This may be accomplished, for example, by control of
the air laying of the individual webs that comprise the composite
sheet 90. For example, by feeding the fibers of the individual webs
to their respective air laying devices at different rates, the
individual webs will be of unequal thickness, and the separation at
the interface 107 (FIG. 10) will not occur in the center of the web
90. As is illustrated in FIGS. 10 and 11, when fabric 90 is
separated in the above described manner, separated faces 99 and 109
of fabrics 98 and 108, respectively, are roughened as a result of
fibers projecting outwardly therefrom.
Outer layer 98 passes upwardly from roller 94 over horizontally
spaced rollers 100 and 102, and thence downwardly between
horizontally aligned cooled squeeze rollers 104 and 106. Facing
layer 108 is guided directly between squeeze rollers 104 and 106,
and suitable lengths of batting are severed from an intermittently
driven supply roll 110 by cutter roll 112 to provide individual
batt sections 118 on facing layer 108 prior to passage between the
nip of rollers 104 and 106.
Impervious sheet 114 is extruded in situ from a suitable supply 116
and passes downwardly between outer layer 98 and pads 118 on facing
layer 108. Faces 99 and 109 of fabrics 98 and 108, respectively,
come into contact with film 114 while it is freshly extruded and
still tacky, and the roughness of these faces causes these fibers
to adhere tenaciously to film 114. The resulting composite assembly
is cooled by a cooling medium such as water which enters rolls 104
and 106 from supplies 122.
A further diaper embodiment is illustrated in FIG. 12, and as shown
therein, the moisture-impervious film 124 has the same dimensions
as the batt 126, with the facing 128 and the outer layer 130 being
larger than the film 124 and batt 126, so that only layers 128 and
130 are present in the edge portion of the diaper. This structure
is somewhat easier to pin, somewhat more pliable, but also has
somewhat reduced strength in the pinning and waistband areas.
It will be understood by those skilled in the art that variations
and modifications of the specific embodiments described above may
be employed without departing from the scope of the invention as
defined in the appended claims.
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