U.S. patent number 3,663,348 [Application Number 04/729,784] was granted by the patent office on 1972-05-16 for a lofty and soft nonwoven, through bonded fabric.
This patent grant is currently assigned to Johnson & Johnson. Invention is credited to Gerald J. Liloia, Louis F. May, Jr., Frederick K. Mesek, Norman Schiff, Robert C. Shepherd, William R. Strickel.
United States Patent |
3,663,348 |
Liloia , et al. |
May 16, 1972 |
A LOFTY AND SOFT NONWOVEN, THROUGH BONDED FABRIC
Abstract
An improved lightweight fabric formed predominantly of
short-length cellulosic fibers with a minor percentage of long
fibers in a substantially homogeneous non-woven web, improved
products such as a diaper made therefrom and improved methods of
manufacture.
Inventors: |
Liloia; Gerald J. (North
Brunswick, NJ), May, Jr.; Louis F. (Old Bridge, NJ),
Schiff; Norman (Kendall Park, NJ), Mesek; Frederick K.
(Downers Grove, IL), Shepherd; Robert C. (Oak Lawn, IL),
Strickel; William R. (Chicago, IL) |
Assignee: |
Johnson & Johnson
(N/A)
|
Family
ID: |
24932615 |
Appl.
No.: |
04/729,784 |
Filed: |
May 16, 1968 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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515874 |
Dec 23, 1965 |
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Current U.S.
Class: |
428/171; 428/74;
604/374; 604/365; 604/375; 442/416 |
Current CPC
Class: |
D21H
5/26 (20130101); A61F 13/51 (20130101); A61F
13/15658 (20130101); A61F 13/51474 (20130101); D21H
27/00 (20130101); Y10T 442/698 (20150401); A61F
13/511 (20130101); Y10T 428/237 (20150115); Y10T
428/24603 (20150115) |
Current International
Class: |
A61F
13/15 (20060101); A61f 013/18 (); B32b 005/16 ();
D04h 001/12 () |
Field of
Search: |
;161/116,151,155,164,169,170,162 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goolkasian; John T.
Assistant Examiner: Moxon, II; George W.
Parent Case Text
This is a continuation-in-part of our copending application Ser.
No. 515,874, filed Dec. 23, 1965 and now abandoned.
Claims
What is claimed is:
1. A lofty and soft nonwoven, through bonded fabric comprising a
machine laid web having a machine direction and a cross direction,
said fabric consisting essentially of predominantly short fibers, a
minor percentage of long fibers and a low viscosity, water
dispersible binder applied throughout said fabric in an amount
between about 1 percent and about 30 percent of the weight of the
fibers on a dry solids basis, said short fibers comprising
cellulosic fibers having lengths less than one-quarter inch, said
cellulosic fibers comprising no less than about 75 percent by
weight of the fiber content of said fabric, said long fibers
comprising separated synthetic fibers having substantially uniform
lengths greater than three-quarters inch, said synthetic fibers
comprising no more than about 25 percent by weight of the fiber
content of said fabric, said short fibers and said long fibers
being substantially randomly disposed and distributed throughout
said fabric, said fibers being interconnected by said binder to
form a network, said web having a greater tensile strength in the
machine direction in comparison to the tensile strength in the
cross direction, said fabric having a weight of less than about 8
ounces per square yard and a density of about 0.15 to about 0.05
gram per cubic centimeter.
2. A nonwoven fabric of claim 1 in which said binder has a
viscosity less than 5 centipoise.
3. A nonwoven fabric of claim 1 in which the long fibers are
synthetic fibers of about 1.5 denier and the unbonded fabric has an
elongation to separation in excess of 60 percent of its original
length.
4. A nonwoven fabric of claim 1 containing long fibers in an amount
within the range of about 2 and about 25 percent by weight of the
total fiber content.
5. A nonwoven fabric of claim 4 wherein said long fibers are
synthetic fibers, substantially all of which have lengths of at
least 1 inch.
6. A nonwoven fabric of claim 5 wherein said long fibers are
synthetic fibers of about 11/2 inches in length.
7. A nonwoven fabric of claim 4 wherein said long fibers are
substantially all synthetic fibers cut to a single predetermined
length.
8. A nonwoven fabric of claim 1 in which the major portion of said
cellulosic short fibers has a length within the range of about
one-sixteenth to one-quarter inch.
9. A nonwoven fabric of claim 8 having on at least one surface
embossing in the bonded fabric whereby the drape characteristics
thereof are enhanced.
10. A nonwoven fabric of claim 1 wherein the binder is applied to
and dried on the fibers without substantial compression
thereof.
11. A nonwoven fabric of claim 8 in which the surface fibers on one
side have substantially more loft than the surface fibers on the
other side.
12. A nonwoven fabric of claim 8 in which the fibers are bonded
together with a cured crosslinked acrylate copolymer in an amount
within the range between about 1 and about 30 percent of the weight
of the fibers on a dry solids basis.
13. A wettable absorbent nonwoven fabric of claim 1 in which said
bonded fabric contains a rewetting agent.
14. A nonwoven fabric of claim 1 wherein said short fibers are wood
pulp and said long fibers are cut rayon.
Description
The present invention relates to fabrics formed predominantly of
short-length cellulosic fibers, the method of making the same, and
products formed therefrom.
Because of the cost savings that can be realized by using
short-length fibers, such as the fibers of wood pulp or cotton
linters, it has been a desideratum in the manufacture of fabrics
and fabric-like materials to use such fibers as compared to the
longer fibers of one-half inch or more in length generally used.
The preparation of fabrics and fabric-like materials has, however,
heretofore been limited to the use of at least a very substantial
percentage of these longer fibers, generally referred to in the
trade as textile-length fibers, and to relatively heavy fabrics
because of the inability heretofore to make, from the
shorter-length fiber, products having the strength, light weight
drape and softness and feed characteristics generally associated
with fabrics formed of such longer-length fibers.
Paper, absorbent wadding, and the like have been made from the
shorter-length cellulosic fibers. Papers, formed by the
conventional paper making processes wherein the fibers are
assembled in a wet slurry and wherein the fibers are held together
through a hydrogen bond, are relatively stiff dense products
lacking the highly desirable characteristics heretofore referred
to. Wood pulp fibers, and the like, have been gathered together in
a low density bulk mass, wherein the fibers have relatively few or
no hydrogen bonds holding the same together, to form highly
absorbent bulk materials. Wood pulp fibers also have been formed
into sheet-like materials of relatively low density wherein the
fibers are partially bonded together, the same being referred to as
cellulose wadding. However, these sheets of cellulose wadding are
quite fragile, having extremely low wet and dry strengths and are
completely unsuitable as a substitute for textile materials.
Accordingly, where fabric-like materials have heretofore been made
by processes other than weaving, such, for example, as felting or
fiber-laying with bonding, the same have been made entirely of
textile-length fibers or of a mixture of fibers comprising
predominantly textile-length fibers or a substantial percentage of
textile-length fibers in a relatively heavy fabric.
In accordance with the present invention, fabric-like materials are
prepared predominantly of fibers having a length of less than
one-quarter inch and in many instances, as hereinafter more fully
described, formed almost entirely of such shorter-length
fibers.
With the growing demand for disposable articles, there has been an
increasing demand for fabric-like materials which avoid the expense
and processing of woven fabrics. As a result there has been an
increasing demand for and production of nonwoven fabrics. However,
the cost can still be further reduced with equivalent or enhanced
physical characteristics where the fabric-like materials are made
using predominantly the less expensive short-length fibers such as
wood pulp fibers and second cut cotton linters processed in
accordance with this invention.
It is an object of the present invention to prepare lightweight
fabrics and fabric-like materials having a good hand or feel, loft,
softness, elongation, drapability and strength from predominantly
short-length cellulosic fibers.
It is another object of this invention to provide such lightweight
fabrics or fabric-like materials from predominantly short-length
fibers where the longer fibers are relatively long and uniform to
provide an interconnecting and strength giving network for the
short fibers.
A still further object is to prepare disposable diapers and the
like made predominantly from short-length fibers.
Other objects and advantages of this invention will become apparent
from the following description taken in connection with the
accompanying drawings which set forth by way of illustration and
example certain embodiments thereof.
IN THE DRAWINGS:
FIG. 1 is a schematic view showing the preparation of a fabric of
the present invention;
FIG. 2 is a perspective view illustrating a swatch of fabric of the
present invention;
FIG. 3 is a perspective view illustrating a modification of the
fabric of the present invention;
FIG. 4 is a perspective view illustrating a further modification of
the fabric of the present invention;
FIG. 5 is a schematic view showing the preparation of fabric of the
present invention in a manner to produce a modified fabric;
FIG. 6 is a perspective view illustrating a swatch of fabric
prepared in the manner of FIG. 5;
FIG. 7 is a perspective view of a diaper of the present
invention;
FIG. 8 is a cross-sectional view taken along lines 8--8 of FIG. 7;
and
FIG. 9 is an illustration of the diaper of FIG. 7 in a prefolded
state.
The fabrics of the present invention have a fiber content which is
predominantly short fibers. By way of definition, "short fibers,"
as used herein, means wood pulp, cotton linters or the like where
the fiber lengths are less than one-quarter inch in length. Between
75 and 98 percent of the total fiber content in the fabrics of this
invention are such short fibers. Both wood pulp and cotton linters
are substantially less expensive than the textile-length cellulosic
fibers of cotton and rayon generally employed in making both woven
and nonwoven cellulosic fabrics. In the preferred embodiments, the
wood pulp fibers and the second cut cotton linters generally have a
length not exceeding about one-quarter inch with the average length
being from about one-sixteenth to three-sixteenth inch.
Accordingly, the fabrics of the present invention have a fiber
content in which between 75 and 98 percent of the fibers are less
than one-quarter inch in length.
" Textile length fibers" or "long fibers" in this specification
means fibers at least three-fourths inch in length, and in the
preferred forms of the invention the long fibers are all of
substantially the same length, preferably produced synthetically
and preferably at least 1 inch long. In one preferred embodiment
made in accordance with Example I, 1.5 denier rayon long fibers
were used which were uniformly cut to about 11/2 inch lengths and
homogeneously and randomly dispersed with the short fibers.
Surprisingly high tensile strengths are thereby attainable provided
the short fibers are thoroughly and efficiently separated and the
short and long fibers are carefully and thoroughly blended and
intermixed.
The fabrics of the present invention have fabric weights in the
rang of 1 to 8 oz./yd..sup.2 ; a density of less than 0.15
gram/c.c., the density generally being in the range of 0.100
gram/c.c. to 0.050 gram/c.c.; and for a fabric having a weight of
about 1.5 oz./yd..sup.2, a dry strength of at least 0.15 pound/inch
of width in machine direction and 0.10 pound/inch of width in the
cross direction. The fabrics have unusually good elongation, loft,
softness and drape characteristics when compared with prior
products incorporating any substantial amount of short fibers.
The fabrics are prepared by first forming a web of randomly laid
dry fibers, the web when laid having a density of about 0.09
gram/c.c. to 0.025 gram/c.c. measured by ASTM Method D-1777 at 0.16
pound/square inch (test procedure set forth in the manual of The
American Society for Testing Materials). Where wood pulp fibers are
used, the same are generally obtained in the form of a fiberboard
of fairly dense construction from which the fibers must be
separated. These wood pulp fibers generally have a fiber length
ranging from a fine dust to about one-quarter inch.
Short-length fibers are best classified by the Clark Classification
procedure described in the test manual of The Technical Association
of Pulp and Paper Industry (TAPPI -- T233 SU64). In this procedure
a water slurry of the fibers is passed through a series of graded
screens. Using this technique, which avoids grinding the fibers,
second cut cotton linters are found to have the following
composition:
30% retained by a 12 mesh screen
22% retained by an 18 mesh screen
14% retained by a 30 mesh screen
16% retained by a 50 mesh screen
18% passed through 50 mesh screen
In making the short fiber fabrics of the present invention a web of
dry fibers is first formed. In the preferred method of manufacture,
the web is then impregnated with a binder by flowing a solution or
dispersion of the binder through the web. The impregnated web is
then subjected to suction to remove excess binder and assure
uniform distribution of binder throughout the fiber web. This
impregnation by binder followed by suction is hereinafter referred
to as suction-bonding. The fiber web at this point has, in one
embodiment on a solids basis, 4 to 6 percent dry solids add-on by
weight of the web. Depending upon the strength requirements of the
web, the loft and the softness desired in the end product, the
range of dry solids added on may vary over the range of about 1 to
about 30 percent. The web so formed is then dried and heated to
cure the binder. This can be done simultaneously by passing into a
drying oven heated to a temperature of about 310.degree. to
320.degree. F. where the same is dried and the binder cured. The
preferred binders are of the self-curing acrylic latex family, the
urethane family, or other binders which can be utilized in low
viscosity solutions or suspensions.
This invention has especial advantages in the manufacture of
lightweight, low density, lofty, and soft fabrics. The especially
useful range of fabric densities in accordance with this invention
is from about 0.05 gram/c.c. to about 0.15 gram/c.c. By the use of
the teaching of this invention and the combination of fibers and
parameters set forth herein, it was found possible to manufacture
lightweight fabrics, that is, fabrics having weights of less than 8
ounces per square yard and handle the product, air blown or
otherwise assembled dry, during further processing. Thereby
unusually desirable weights, densities and other physical
characteristics are obtained.
The preparation of predominantly short fiber fabrics in accordance
with the present invention is illustrated schematically, for
example, in FIG. 1. Referring to FIG. 1, a web 10 of mixed randomly
disposed short fibers 11 and long fibers 19 are deposited from
fiber-laying equipment 12 onto a foraminous moving screen or belt
13. The fiber-laying equipment 12 is preferably of the air
deposition type such as a modified RANDO WEBBER made by The
Curlator Co. The low density fiber web 10 is moved by belt 13 below
a screen containing a weir box 14 of binder in solution or aqueous
dispersion form. The binder fluid is flowed onto and through the
web 10 in quantities substantially in excess of the ultimate amount
to be deposited on the fibers completely impregnating the web. The
web 10, immediately after impregnation with the binder solution,
passes over a suction box 15 where excess binder is removed. The
impregnated web 10 is conveyed by belt 13 through a dryer 16. The
fabric is then removed from belt 13 and collected, for example, on
fabric roll 17. A section of fabric so formed is illustrated, for
example, in FIG. 2 of the drawings showing a very small percentage
of long fibers 19. An alternate construction with a larger
percentage of long fibers 19 is shown diagrammatically in FIG. 3.
The binder should be of the low viscosity type to maintain the
features of the invention described. A "low viscosity binder" is
generally one having the desired adhesive qualities and a viscosity
less than 5 centipoises.
The binder, in the preferred method of manufacture, is flowed onto
the fabric from the weir box 14 and a major proportion thereof is
withdrawn in the suction box 15 before the fabric enters the dryer
16. It is important in attaining the lofty and soft character of
the fabrics made hereunder that the application, removal and drying
of the binder be without substantial compression of the fabric. In
many conventional methods of processing fabrics, excess binder
liquids are squeezed out of the fabric with compression rollers or
the like and such processes would generally produce unsatisfactory
products when practicing this invention.
It has been found that the elongation characteristics are enhanced
in fabrics made in accordance with this invention. One set of
samples was constructed with about 21/2 oz./yd..sup.2 of fiber
weight and utilizing wood pulp as the short fibers and about 11/2
inch 1.5 denier rayon staple as the long fibers. In the set, the
percentage of long fibers was varied, and the elongation tests were
performed on the unbonded web. Over the range of interest, the
percentage of elongation varied from about 60 to 94 percent. The
elongation was measured by stretching a sample of the fabric
between two clamped ends and measuring the percentage increase in
length before the two ends separated. This parameter is an
indication of the usefulness of the fabric in many applications
such as towel materials, cosmetic pads, and elsewhere where
conventional tensile strength is not a singular criteria to be
considered. When bonded, the samples were found to have comparable
but somewhat lower elongation characteristics.
Based on the samples tested, a fabric made of 98 percent short
fibers has about a 60 percent elongation, both in the machine
direction and in the cross direction. Samples made of 85 percent
short fibers with 15 percent long fibers exhibited an elongation of
about 88 percent, and samples containing 75 percent short fibers
showed an elongation of about 94 percent. It has been found that
there is a substantial increase in elongation characteristics with
the addition of about 2 percent of long fibers to an otherwise
short fiber fabric. The percentage of elongation rises very rapidly
with the addition of long fibers up to about 2 percent and
continues to increase for increases in long fibers up to 10 percent
at a diminishing rate. As the percentage of long fibers is
increased from about 10 to about 25 percent, the elongation
characteristics improve rather consistently and more gradually.
However, it has been found that additional long fibers in excess of
about 25 percent do not increase the elongation characteristics at
the same rate and actually reduce the elongation in some cases. A
sample made of 100 percent long fibers and no short fibers showed
an elongation in both directions of approximately 60 percent and a
sample made of 100 percent short fibers exhibited an elongation of
28 percent.
It is extremely difficult to handle a web of randomly disposed dry
fibers of predominantly short fiber length in webs of 8
oz./yd..sup.2 or less through the bonding equipment and
subsequently through the drying apparatus. In fact, handling of
fabrics having weights of less than 2 oz./yd..sup.2 had been
considered unworkable prior to this invention. It has been found
that this problem can be overcome through use of the teaching of
this invention.
Referring to FIG. 5, a means is schematically shown for
manufacturing a fabric having two distinctly different surface
characteristics. A relatively thin web 21 of dry, mixed fibers 11
and 19 is first laid down, superimposing on the same is a loose
weave fabric 22 such as a low count gauze, cotton scrim, or the
like. A second relatively thin web 23 of dry fibers 11 and 19 is
then deposited onto the loose weave fabric 22. The dry laminate so
formed is suction-bonded, dried, and cured in the manner previously
described. The laminate is then split into two fabrics 24 and 25,
the laminate separating at the point of intersection of the loose
weave fabric. The loose weave fabric 22 is removed and the fabrics
24 and 25 wound on separate rolls 26 and 27. Other methods of
splitting may be employed with or without an actual dividing web
22.
By first forming and then splitting the web, fabrics having unique
surface characteristics are formed including short fibers, the
fabrics having excellent drape, loft and elongation
characteristics. A section of fabric formed by the split web
technique is illustrated in FIG. 6. The fabric is quite similar to
that of FIG. 2 differing primarily in that the fibers 28, on the
surface previously adjacent the loose weave fabric 22, have
substantially more loft than the fibers on the other surface of the
fabric. The apparatus of FIG. 5 is schematically illustrated as in
FIG. 1, 12' indicating fiber-laying equipment, 13' a moving belt,
14' a binder container and dispenser, 15' a suction box, and 16'
heating and drying apparatus.
In some constructions, it is desirable to have even greater
drapability than would result from the construction features
already described. Increased drape can be attained without
significant loss of loft, softness or strength by embossing the
fabric after completion of the processes shown in FIGS. 1 and 5.
This produces a fabric such as shown in FIG. 4 where the fibers 11
and 19 have been subjected to embossing pressure along the lines
20.
The fabrics so far described are not in and of themselves water
absorbent as the bonding agent appears to sufficiently coat the
individual fibers as to interfere with their normal water-absorbent
characteristics. Absorbent fabrics can be made, however, by
treating the fabric with a rewetting agent such, for example, as an
anionic sulfonated alkyl ester. In the preferred practice of making
the fabrics of the present invention, the rewetting agent is
included in the impregnating solution or suspension together with
the binder. By including the rewetting agent at this step in the
manufacture of the fabrics, the same are found to be readily
wettable and highly absorbent.
The preparation of fabrics of the present invention are further
illustrated by the following examples. The examples are given for
the purpose of illustration only, and the invention is not limited
thereto.
EXAMPLE I
A fibrous web composed of approximately 15 percent textile-length
fibers such as uniformly cut 11/2 inch 1.5 denier rayon fibers and
85 percent fibers of individualized second cut cotton linters is
made on a web laying device to a weight of 2 oz./yd..sup.2. This
web is then conveyed into a bonder as heretofore described using a
preferred bonding agent such as a self-crosslinking acrylic
emulsion. The composition of the binder suspension and the amount
of suction at the suction slot is controlled so as to give the
fabric a dry solids add-on of 4.75 percent based on the fabric
weight. The wet web is conveyed into a drying oven having a
temperature of 310.degree.-320.degree. F. where it is dried and the
resin binder cured. The resultant material has a density of 0.05 to
0.07 gram/c.c., a dry strength of about 1.4 pounds/inch of width in
the machine direction and about 0.8 pound/inch of width in the
cross direction. The wet strengths are about 0.9 pound/inch of
width in the machine direction and about 0.5 pound/inch of width in
the cross direction. The fabric has excellent hand or feel and
drape.
EXAMPLE II
A fibrous web composed of approximately 25 percent textile-length
fibers such as uniform 1.5 denier 1 inch rayon fibers and 75
percent fibers of ground up douglas fir beleached kraft pulp is
made on a web laying device to a weight of 1.5 to 2 oz. per square
yard. The web is then conveyed into a section bonder heretofore
described using the bonding agent HYCAR 2600 .times. 120. The
composition of the binder suspension and the amount of suction at
the suction slot is controlled to give the fabric a dry solids
add-on of about 25 percent based on the fiber weight. The wet web
is conveyed into a drying oven having a temperature of
310.degree.-320.degree. F. where it is dried and the resin binder
cured. The resultant web has a density of 0.08 gram/c.c.; a dry
strength of about 7 pounds per inch of width and a wet strength of
about 2.2 pounds per inch of width in the machine direction.
EXAMPLE III
A fibrous web composed of approximately 10 percent textile-length
fibers such as uniform 1.5 denier 11/2 inches rayon fibers and 90
percent douglas fir pulp is made to a weight of 1.5 oz./yd..sup.2.
The web is then passed through a section bonder and receives
thorough impregnation with HYCAR 2600 .times. 120. The composition
and viscosity of the binder suspension and amount of suction are
controlled to give the fabric a dry solids add-on of about 1
percent based on the fiber weight.
The wet web is conveyed into a drying oven having a temperature of
310.degree. to 320.degree. F. where it is dried and the resin
cured. The resultant fabric has a density of 0.06 gram/c.c., a dry
tensile strength of 0.18 pound/inch in the machine direction and
0.13 pound/inch in the cross direction, and the bonded fabric shows
an elongation of 50 percent before separation.
EXAMPLE IV
A fibrous web composed of approximately 13 percent textile-length
fibers such as uniform 1.5 denier 11/2 inches rayon fibers and 87
percent douglas fir pulp is made to a weight of 8 oz./yd..sup.2.
The web is then passed through a suction bonder and receives
thorough impregnation with HYCAR 2600 .times. 120. The composition
and viscosity of the binder suspension and amount of suction are
controlled to give the fabric a dry solids add-on of about 1.5
percent based on the fiber weight.
The wet web is conveyed into a drying oven having a temperature of
310.degree. to 320.degree. F. where it is dried and the resin
cured. The resultant fabric has a density of 0.09 gram/c.c., a dry
tensile strength of 1.9 pounds/inch in the machine direction and
1.4 pounds/inch in the cross direction, and the bonded fabric shows
an elongation of 70 percent before separation.
EXAMPLE V
A fibrous web composed of approximately 5 percent textile-length
fibers such as uniform 1.5 denier 11/2 inches rayon fibers and 95
percent douglas fir pulp is made to a weight of 2.3 oz./yd..sup.2.
The web is then passed through a suction bonder and receives
thorough impregnation with HYCAR 2600 .times. 120. The composition
and viscosity of the binder suspension and amount of suction are
controlled to give the fabric a dry solids add-on of about 2
percent based on the fiber weight.
The wet web is conveyed into a drying oven having a temperature of
310.degree. to 320.degree. F. where it is dried and the resin
cured. The resultant fabric has a density of 0.07 gram/c.c., a dry
tensile strength of 0.56 pound/inch in the machine direction and
0.40 pound/inch in the cross direction, and the bonded fabric shows
an elongation of 46 percent before separation.
The fabrics described above have been utilized as cosmetic pads,
lithographic wipes, operating room towels and diapers. The
excellent hand, feel and drape qualities of the fabrics give
diapers made therefrom much the same feel and handling qualities as
diapers formed of woven fabrics. However, the use of the short
textile fibers, such as wood pulp and cotton linters, permits the
same to be manufactured at a price substantially below that of
woven fabrics or the conventional nonwoven fabrics thus keeping the
cost of the final diaper well within a price such that the same can
be disposed of after use.
A diaper of simple inexpensive construction using a fabric of the
present invention is illustrated, for example, in FIGS. 7, 8 and 9.
The diaper is formed of a top fabric sheet 29 and a bottom fabric
sheet 30, the fabric sheets 29 and 30 being made in accordance with
the present invention in the manner previously described. Between
fabric sheets 29 and 30 is an absorbent pad 31 formed of wood pulp,
or other highly absorbent material. The absorbent pad 31 is
substantially narrower in width than the top and bottom fabric
sheets 29 and 30 and is spaced from the edges of sheets 29 and 30
to lie along the center portion of the diaper, i.e., the portion
which would, in use, be positioned at the crotch of the infant. The
bottom fabric sheet 30 may be longer than the top fabric sheet 29,
the extending ends 32 and 33 being folded over to form reinforced
areas 34 and 35 for receiving safety pins and the like when
applying the diaper. However, if desired, the top and bottom sheets
may be of substantially the same length and a strip of gauze or
other woven fabric inserted between the two sheets at each end to
reinforce the diaper in these areas.
In forming the diaper, both the top fabric sheet 29 and the bottom
fabric sheet 30 may be formed of an absorbent fabric, i.e., one
which contains a rewetting agent, or the diaper may be formed with
only the top fabric 29 and the absorbent filler 31 being absorbent
while the bottom fabric 30 is nonabsorbent, the same having been
prepared in the manner described without being rendered absorbent
through the inclusion of a rewetting agent.
Where the fabrics 29 and 30 of the diaper are made through the
split web technique heretofore described, the side of each fabric
sheet which was in the inner portion of the web prior to splitting
has appreciably more fiber loft than the other side of the fabric.
This loft is quite beneficial in forming a several ply construction
such as the diaper construction just described. The loft sides of
the fabrics are placed in face-to-face contact with each other on
either side of the filler or absorbent pad 31. The loft fibers tend
to interlock when the surfaces are pressed together. The fabrics 29
and 30 are thus mechanically united along their edges on each side
of the absorbent pad 31 to give the appearance and feel of a single
fabric. This also prevents the absorbent pad 31 from shifting its
position. The side edges 36 and 37 of the diaper may or may not be
further secured through spot bonding along the edge to prevent an
initial separation of the fabrics 29 and 30 along such edges if
desired.
As the fibers of fabrics 29 and 30 are through bonded, there is no
problem with fraying edges and the like so that hems or other
structure for prevention of edges fraying is not necessary. Because
of its simple construction, the whole diaper can be assembled
relatively easily.
In order to improve the ease with which the diaper is applied, the
portions extending along each side of absorbent pad 31 are folded
in towards the center of the diaper and then back on themselves to
form two double folds 38 and 39, one along each side of the diaper.
This is illustrated in FIG. 9. The double fold along each side is
stabilized by adhesive 40 and 41 being applied near the center
portion of each double fold as measured from the diaper ends. This
may either be a permanent or temporary adhesive as the primary
purpose of the adhesive is to hold the center portion of the folds
in place while the end portions of the folds are opened in applying
the diaper.
Particular embodiments of the invention have been used to
illustrate the same. The invention, however, is not limited to
these specific embodiments. In view of the foregoing disclosure,
variations or modifications thereof will be apparent, and it is
intended to include within the invention all such variations and
modifications except as do not come within the scope of the
appended claims.
* * * * *