U.S. patent number 3,908,659 [Application Number 05/451,312] was granted by the patent office on 1975-09-30 for absorbent pad structure, diaper construction utilizing same and methods of manufacture thereof.
This patent grant is currently assigned to The Procter & Gamble Company. Invention is credited to John Richard Noel, Bernard Martin Wehrmeyer.
United States Patent |
3,908,659 |
Wehrmeyer , et al. |
September 30, 1975 |
Absorbent pad structure, diaper construction utilizing same and
methods of manufacture thereof
Abstract
Absorbent pad made of air-laid fiberized or disintegrated pulp
lap dry embossed to provide a bilaterally staggered pattern such as
a close packed hexagonal pattern of low density tufts surrounded
and separated by bilaterally extending non-linear and preferably
sinuous regions of higher density to provide high softness
impression together with high moisture wicking and transport and
high surface dryness impression, methods of manufacture thereof by
patterned densification as by compression in a calender stack
between a patterned roll and a generally smooth back up roll, and
diapers incorporating such pads between a top sheet and a back
sheet.
Inventors: |
Wehrmeyer; Bernard Martin (Park
Hills, KY), Noel; John Richard (Cincinnati, OH) |
Assignee: |
The Procter & Gamble
Company (Cincinnati, OH)
|
Family
ID: |
23791715 |
Appl.
No.: |
05/451,312 |
Filed: |
March 14, 1974 |
Current U.S.
Class: |
604/374; 604/375;
604/380 |
Current CPC
Class: |
A61F
13/533 (20130101); A61F 2013/51078 (20130101); A61F
2013/53721 (20130101); A61F 2013/53908 (20130101); A61F
2013/5395 (20130101); A61F 13/202 (20130101); A61F
2013/15821 (20130101); A61F 13/539 (20130101); A61F
13/537 (20130101) |
Current International
Class: |
A61F
13/15 (20060101); A61F 13/20 (20060101); A61F
013/16 (); A61L 015/00 () |
Field of
Search: |
;128/29W,284,217,287,296,156 ;161/123,114 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Medbery; Aldrich F.
Attorney, Agent or Firm: Lackenbach; Elliot A. Gorman; John
V. Witte; Richard C.
Claims
1. Absorbent pad structure combining high wicking and moisture
transport capability with high liquid absorptive capacity to
provide high surface dryness impression and high softness
impression comprising, in combination,
an air laid pad of generally uniform weight basis consisting
essentially of disintegrated cellulose pulp lap contained within a
paper tissue envelope defining therewith means for providing
structural integrity thereto, together with
means for providing regions having high liquid absorptive capacity
spaced apart throughout the pad, and
means for providing enhanced capillary wicking and thereby
providing high liquid transport of absorbed moisture within the pad
to portions of the pad remote from the point of moisture
application, wherein
said means for providing regions of high liquid absorptive capacity
comprises a bi-laterally staggered array of spaced apart generally
circular tufts formed by undensified regions of relatively low
density, and
said means for providing enhanced capillary wicking comprises a
bi-laterally extending pattern of intersecting non-linear higher
density regions densified essentially only by the application of
selective pressures thereto surrounding, separating and extending
between each of said low density tufts,
said non-linear densified high density regions comprising between
approximately twenty and fifty percent of the area of said pad to
thereby enable said staggered array of spaced apart generally
undensified generally circular tufts and said bi-laterally
extending pattern of intersecting non-linear higher density regions
together to define means for providing both high dryness impression
and high softness impression
2. Diaper structure comprising an absorbent pad structure as
defined in
3. Absorbent pad structures defined in claim 1 wherein said higher
density densified regions comprise between approximately thirty and
forty percent
4. Absorbent pad structure defined in claim 1 wherein said pattern
densification comprises compressed region formed by compression
effected substantially from an absorbent face of said pad structure
so that a residual density gradient exists normally through said
pad and said tufts extend with substantial height and resilience
above said higher density regions to loft said higher density
regions away from surfaces in contact with said absorbent face and
the pad resilience additionally extends said tufts a lesser
distance from the densified region on the reverse side of
5. Diaper structure comprising an absorbent pad structure defined
in claim
6. Absorbent pad structure defined in claim 4 wherein said
nonlinear high density regions extend generally sinuously
bilaterally across said pad, and wherein said low density generally
circular tufts are arranged generally in a close packed hexagonal
array and are of generally uniform diameters of between
approximately three-eighths and three-quarters of an
7. Diaper structure comprising an absorbent pad structure defined
in claim
8. Absorbent pad structures defined in claim 6 having an average
density of approximately 0.14 grams per cubic centimeter and
wherein said circular
9. Diaper structure comprising an absorbent pad structure as
defined in claim 8 disposed between a urine permeable top sheet and
a back sheet.
Description
FIELD OF THE INVENTION
This invention relates generally to disposable absorbent pad
structures.
DESCRIPTION OF THE PRIOR ART
Absorbent pads fabricated of air-laid fiberized pulp lap and
disposable diapers utilizing such pads are known in the prior art.
Such air-laid structures may be formed on a paper tissue and an
example of fiberizing or disintegrating pulp lap and felting
thereof for manufacture of such a product is disclosed, for
example, in prior U.S. Pat. Nos. 3,519,211 to Sakulich, et ano and
3,750,962 to Morgan, Jr., and co-pending application, Ser. No.
182,795, filed Sept. 22, 1971, by Kenneth B. Buell, now Pat. No.
3,825,194 and assigned to the assignee of this application. The
disclosure of the aforesaid patents and application Ser. No.
182,795 are hereby incorporated herein, by reference, as fully and
completely as if physically reproduced hereat and throughout this
application the term "fiberized" and "disintegrated" pulp lap and
"air-laid" pads and webs are intended to refer to a product such as
that formed in accordance with said patents and application.
It has also been previously suggested to fully enclose such an
air-laid felt pad or bat within a tissue envelope to aid in
supporting the felt during processing, including converting, and to
aid in preventing disintegration thereof during use. See, e.g.,
Kalwaites U.S. Pat. No. 3,444,859; Schutte U.S. Pat. No. 3,741,212;
Costanza et al. U.S. Pat. No. 3,769,978.
It has also been recognized that increased wicking and fluid
transfer or transport within such a structure may be accomplished
by densifying or compressing the structure to provide an increased
density thereof as suggested in, e.g., Duncan U.S. Pat. No.
3,592,194; Krusko, U.S. Pat. No. 3,721,242; and DeKnight U.S. Pat.
No. 3,769,978. It has even been suggested that a one directional
generally sinuous pattern of compressed narrow strips may produce
enhanced distribution of moisture in such a structure
longitudinally along such strips. However, such narrow compressed
strips have also been recognized as barriers reducing transverse
moisture transport and also results in a stiffer and less soft
product and have been formed by processing including wetting of the
pad, and thereby changing the structure from a fully dry air-laid
product. See, e.g., Morin U.S. Pat. No. 2,788,003. Further, it has
been suggested that compressing a pad of the general type referred
to above so as to decrease the thickness thereof and increase the
bulk density, not only creates increased wicking but, in addition,
may produce increased flexibility. See, e.g., Gobbo, Sr. et al.
U.S. Pat. No. 3,065,751. However, the mere increase in flexibility
does not necessarily result in increased softness and what the
prior art has apparently not recognized, is that softness and
flexibility are not the same and, in fact, that structures
exhibiting high flexibility may provide a very low softness
impression to a user. Moreover, the prior art has also apparently
not recognized that subjective surface dryness impressions are not
necessarily consistent with objective tests for surface dryness
and, in fact, subjective surface dryness impressions may be
diametrically opposite objective surface dryness test results.
OBJECTS OF THE INVENTION
Bearing in mind the foregoing, it is a primary object of the
present invention to provide a novel and improved absorbent pad
structure.
Another primary object of the present invention, in addition to the
foregoing object, is to provide such novel and improved absorbent
pad structures having optimized fluid wicking capabilities as well
as surface dryness and softness impressions.
Yet another primary object of the present invention, in addition to
each of the foregoing objects, is the provision of such a novel and
improved absorbent pad structures particularly constituted for use
in a disposable diaper construction and disposable diaper
structures fabricated thereof.
Still another primary object of the present invention, in addition
to each of the foregoing objects, is the provision of novel methods
of manufacture of such absorbent pad and diaper structures.
Yet still another primary object of the present invention, in
addition to each of the foregoing objects, is the provision of a
novel absorbent pad fabricated of air-laid defibered pulp lap,
preferably within a tissue envelope, subjected to dry pattern
densification, as by patterned compression, to provide a
bilaterally extending staggered pattern of low density tufts
surrounded by bilaterally extending non-linear and preferably
sinuously extending regions of increased density particularly
suitable for use in diapers and diaper-like structures and
exhibiting enhanced fluid wicking characteristics, moisture
retention capability, high surface dryness and high subjective
surface dryness and softness impressions.
A yet further primary object of the present invention, in addition
to the foregoing objects, is the provision of novel methods of
subjecting air-laid webs or pads of fiberized pulp lap to patterned
densifications by patterned compression from one side thereof to
provide a tufted structure having a higher tuft height on said one
side than on the other.
A yet still further primary object, in addition to the foregoing
objects, is the provision of improved diapers and diaper like
structures utilizing the improved absorbent pad structures of the
present invention and utilizing such pad structures with the higher
tufted side facing the top sheet for disposition facing the child's
skin in use to provide maximum lofting of the densified regions
away from the child's skin as well as providing the best look and
feel to the outside facing surface.
The invention resides in the combination, construction, arrangement
and disposition of the various component parts and elements
incorporated in improved absorbent pad and diaper structures
constructed in accordance with the principals of this invention and
the methods of manufacture in accordance with the principals of
this invention. The present invention will be better understood and
objects and important features other than those specifically
enumerated above will become apparent when consideration is given
to the following details and description, which when taken in
conjunction with the annexed drawing describes, discloses,
illustrates, and shows a preferred embodiment or modification of
the present invention and what is presently considered and believed
to be the best mode of practicing the principals thereof. Other
embodiments and modifications may be suggested to those having the
benefit of the teachings herein, and such other embodiments of
modifications are intended to be reserved especially as they fall
within the scope and spirit of the subjoined claims.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an
improved absorbent pad structure and a diaper structure utilizing
the same fabricated of air-laid disintegrated cellulose pulp lap
contained within a tissue envelope and dry embossed to provide a
staggered pattern of low density tufts separated and surrounded by
bilaterally extending sinuous regions of higher density providing
an absorbent pad having high fluid capacity, enhanced wicking,
enhanced surface dryness and exhibiting enhanced surface dryness
and softness impression.
In accordance with the present invention, there is provided
absorbent pad structure combining an enhanced softness impression
with enhanced wicking and moisture transport capabilities to
provide enhanced surface dryness impression comprising, in
combination, an air laid-pad of disintegrated cellulose pulp lap
contained within a paper tissue envelope providing structural
integrity thereto, said pad being pattern densified to define
bilaterally staggered spaced apart tufts formed by undensified
regions of low density surrounded by and separated by a bilaterally
extending pattern of densified intersecting non-linear higher
density regions, said densified regions comprising between
approximately 20 and 50 percent of the area of said pad.
DESCRIPTION OF THE DRAWING
While the specification concludes with claims particularly pointing
out and distinctly claiming the subject matter which is regarded as
forming the present invention, it is believed that the invention
will be better understood from the following description which,
taken in conjunction with the annexed drawing, describes,
discloses, illustrates and shows a preferred embodiment or
modification of the present invention and wherein:
FIG. 1 is a plan view, partially broken away, illustrating a
disposable diaper having a pattern densified and tufted absorbent
air-laid pad in accordance with the present invention;
FIG. 2 is an enlarged cross sectional illustration taken along line
2--2 of FIG. 1;
FIG. 3 is a cross sectional illustration diagrammatically
illustrating a method of manufacture of the improved absorbent pad
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawing, there is shown and illustrated in
FIGS. 1 and 2 an improved diaper structure constructed in
accordance with the principals of the present invention designated
generally by the reference character 10.
The diaper as shown in the drawing can be formed, in general, in
accordance with the teachings of U.S. Pat. Re. No. 26,151, issued
to R. C. Duncan et al., on Jan. 31, 1967, and the entire disclosure
thereof is hereby incorporated herein by reference as fully and
completely as if physically reproduced hereat.
The diaper 24 comprises an improved absorbent pad constructed in
accordance with the principals of the present invention and
designated generally by reference character 12. The pad 12 may be
covered by a superposed top sheet 14 which is preferably moisture
pervious and which may provide a barrier between the improved
absorbent pad 12 and a baby's skin. The absorbent pad 12 may be
backed by a back sheet 16 which is preferably moisture impervious
and is larger, at least in width, than the absorbent pad 12 to
provide side flaps 18 which are folded over and onto the top
surface of the top sheet 14 so that the side flaps 18 of the back
sheet 16 overlie the lateral marginal area of the top surface of
the top sheet 14 and the absorbent pad 12 there beneath. The back
sheet 16 may also be larger in length than the absorbent pad 12 and
the top sheet 14 to provide end flaps 20 which are folded over and
onto the top surface of the top sheet 14 so that the end flaps 20
overlie the longitudinal marginal area of the top surface of the
top sheet 14 and underlying absorbent pad 12. Hence, the absorbent
pad 12 is fully contained within an envelope defined by the top
sheet 14 and back sheet 16. The side flaps 18 and the end flaps 20
may be secured together at the corners and to the underlying top
sheet 14 and to the edge portions of the pad 12 in any convenient
manner, as by heat sealing, adhesive bonding, or like.
It is to be emphasized that although the absorbent pad 12 has been
described, disclosed, illustrated, and shown as being bound on both
the sides and ends by the side flaps 18 and end flaps 20,
respectively, so that the absorbent pad 12 is fully contained
within the envelope defined by the top sheet 14 and the back sheet
16, two of such flaps, and particularly the end flaps 20 may be
eliminated while yet enabling retention of the absorbent pad 12
between the top sheet 14 and the back sheet 16. More particularly,
the absorbent pad 12 may be bonded to either or both the top sheet
14 and the back sheet 16, as by, for example and without
limitation, heat sealing, adhesive bonding, pressure bonding, or
the like.
Further, while the present invention is particularly described,
disclosed, illustrated and shown herein as applied to a diaper, it
is to be expressly understood that the present invention is not
limited to use against a baby for the absorption of urine, and the
like, but may be utilized for many other related bandage and
bandage like applications, including, by way of example only and
without limitation, surgical dressings, incontinence pads, sanitary
napkins, and the like.
The side flaps 18, and the end flaps 20 when provided, should have
a minimum width of about 3/8 inch and preferably about 3/4 inch.
The back sheet 16 preferably is a flexible waterproof web, e.g., a
0.001 inch thick, low density, pattern embossed, opaque
polyethylene web.
The top sheet 14 may be either hydrophobic or hydrophilic and may
be fabricated of a tissue paper made by a conventional water-laid
process, subsequently creped; an air-laid tissue, a continuous
filament non-woven web, a micro-porous film, or the like, and may
be treated with wet-strength and/or bonding resins as will be
apparent to those skilled in the art.
The improved absorbent pad 12 comprises a mat, pad, web, or bat 22
of air-laid disintegrated pulp lap formed, for example, in
accordance with the teachings of Sakulich et al. U.S. Pat. No.
3,519,211; Morgan, Jr. U.S. Pat. No. 3,750,962; and co-pending
Buell Application Ser. No. 182,795 filed Sept. 22, 1971 and
assigned to the assignee of the instant application. The mat or bat
22 may be contained between a pair of tissue layers 24 and 26
superposed and subjacent thereto respectively.
The disclosures of the aforesaid patents are hereby expressly
incorporated herein by reference as fully and completely as if
fully set forth hereat.
In addition to sheer absorptive capacity, two desirable attributes
of a disposable diaper and of an absorptive pad for use therein are
surface dryness and softness. Air-felt density is one of the major
factors controlling these attributes. The favorable density ranges
are, however, different for the two attributes. Typically, low
density favors a good softness impression while presenting a poor
skin dryness impression. Alternatively, high density favors a good
skin dryness impression while providing a poor softness
impression.
In other words, typically low density favors a good
softness/flexibility impression while high density favors a good
wicking/skin dryness impression.
In accordance with the present invention, a pattern dry
densification of the pad 12 (including both the fiber mat or bat 22
and the envelope tissues 24 and 26) is performed to provide a
bilateral staggered pattern of tufts 28 of substantially
undensified, i.e., low density regions separated and surrounded by
a generally non-linear bilaterally extending pattern of densified
regions 30 of higher density so that the resultant absorbent pad
structure exhibits both good skin dryness and good softness
impression.
The high density regions 30 which, as heretofore pointed out, are
bilaterally extensive provide good wicking and fluid transport
throughout the pad 12. Good wicking allows the moisture to be
spread more evenly throughout the absorbent material and aids in
attaining good skin dryness.
The low density regions or turfts 28 provide a good softness
impression as well as providing regions having high liquid
absorptive capacity spaced throughout the pad, providing a good
skin dryness impression and, being of substantial height and
resilience, tend to raise or loft the high density, wetter feeling
regions from the baby's skin.
Previously suggested schemes for compressing of air felts or pads
to provide sufficient high density area to offer good wicking and
skin dryness are stiff and boardy, while uncompressed pads which
offer flexibility and softness do not provide sufficiently high
density to provide significant wicking and skin dryness. As has
been pointed out hereinabove, it has been previously suggested to
provide some localized compression of small portions of absorbent
pads. However, such localized compression has been performed,
usually together with the application of water or other liquid,
either immediately prior to or during such compression, and such
localized compression has been applied to only a small percentage
of the pad and primarily for bonding of the pad fibers or layers
together. Moreover, such compressions, done wet or with the
addition of moisture, even if done at staggered location, adversely
affects the softness of the pad. Furthermore, if such compression
is effected along linear strips, as has been previously suggested
for increasing wicking and fluid transport in the direction of the
compressed strips, the adverse effect of such compressed strips on
the overall softness of the pad is especially consequential, and
although wicking and liquid transport parallel such compressed
strips may be improved thereby, such stripes actually inhibit fluid
transport in the transverse direction and act as barriers to
wicking and fluid transport perpendicular thereto. The
densification pattern of the present invention, however, offers
sufficient high density area for good wicking and skin dryness
while remaining soft and flexible. In accordance with the present
invention, the high density areas are basically nonlinear and, in
fact, preferably extend sinuously bilaterally of the pad 12 so as
to maintain flexibility which appears to be a major factor in
overall softness impression.
Densification patterns providing densification of approximately
twenty to fifty percent of the total area appear to be preferable,
although somewhat lower and higher percentages may provide
acceptable, although not optimum results. Below ten percent area
densification, however, insufficient wicking occurs and above
approximately seventy percent densification, the densification
pattern becomes inconsistent, and difficult to maintain and
unsatisfactory softness impressions result.
In accordance with the present invention, and with reference now
more particularly to FIG. 3, the patterned densification of the
air-felt or absorbent pad 12 may be obtained by densifying the
air-felt pad with, for example, a two roll calender stack 32 in
which the pad or air-felt 12 is compressed between a patterned roll
34 which has been debossed with pcokets 36 defining the design
pattern and a smooth backup roll 38 cooperating therewith. The
density in the high density region 30 may be controlled by the
pressure and separation between the patterned roll 34 and the
smooth backup roll 38. The density in the low density regions or
tufts 28 may be controlled by either passing the air-felt or pad 12
through a calender stack designated generally by the reference
character 40, comprising smooth surfaced pressure and backup rolls
42 and 44, respectively prior to passage between the rolls 34 and
38 or by controlling the depth of the debossed regions or pockets
36 in the pattern roll 34 corresponding to the low density regions
or tufts 28.
Preferably, the pattern of tufts is staggered so that no straight
lines can be extended across the densified region 30 which extends
for any substantial distance in any direction. In other words,
preferably the tufts or low density region 28 are of sufficient
diameter and spacing that, in any direction, their edges extend
past one another. Further, the tufts should be of sufficient size
to maintain their integrity, i.e., approximately 3/8 inch to 3/4
inch diameter with the preferable size being approximately 9/16
inch in diameter.
In practice, however, it has been found acceptable to define the
densification pattern to position the low density, undensified
regions or tufts 28 in a close packed regular hexagonal arrangement
as shown in FIG. 1 even if, as shown, extremely narrow linear
regions may exist, i.e., as designated by the center lines a, b,
and c in FIG. 1 and as shown in emphasized form and designated 46
in FIG. 2 without substantially adversely affecting the softness
impression, provided that such linear regions are very narrow so as
to constitute only a small percentage of the total area of the pad
12 and the generally sinuously bilaterally extending pattern of
densification.
It is also to be emphasized that, as used herein, the term
"bilateral" or "bilaterally" is used and intended to mean extending
in or having vectors extending in at least two directions, and not
limited to only two directions. Hence, within the meaning hereof,
the generally hexagonal pattern of FIG. 1 having lines of direction
A, B, and C is a bilaterally extending one, having lines of
definition extending both generally towards the ends (i.e., line A,
as well as B and C) of the diaper 10 and generally towards the
sides (i.e., lines B and C) thereof.
The term "tuft" as used herein is intended to cover and define a
region of low density having substantial area projecting from the
surrounding high density region a significant amount and possessing
substantial resilience and height. Hence, tufts of the present
invention may have diameters on the order of 3/8 to 3/4 inch or
more, having a thickness 2-3 times the thickness of the densified
region.
EXAMPLE 1
To substantiate the surface dryness qualities of the present
invention, a test was run, the object of which was to compare the
subjective surface dryness of diapers incorporating the same
average basis weight and the same average density air-felt pads,
differing only in that one sample was of generally uniform density
while the other had been subjected to pattern densification in
accordance with the present invention. Sample L was a disposable
diaper incorporating an air-felt pad having a generally uniform
density of approximately 0.14 grams per cubic centimeter and a
generally uniform thickness of approximately 0.085 inches. Sample N
was a similar disposable diaper using a similar air-felt pad having
an average density of approximately 0.14 grams per cubic centimeter
but which had been subjected to pattern densification over
approximately 50 percent of the area to provide generally circular
tufts arranged in a close packed hexagonal staggered pattern of the
type shown in FIG. 1 covering approximately 50 percent of the area
and having a diameter of approximately 9/16 inches and an overall
tuft height of approximately 0.150 inches. The densified regions
extended bilaterally sinuously around and between the undensified
tufts and had been densified to a thickness of approximately
0.50-0.60 inches. The densified regions accordingly had a density
of approximately 0.20 grams per cubic centimeter. The samples were
laid flat and each was wet with 114 cubic centimeters of a one
percent saline solution adjusted to have a surface tension of 45
dynes. The test solution was applied generally to the center of
each sample and allowing the sample approximately 30 minutes in
which to absorb the water. Except when being tested, the samples
were kept under polyethylene to minimize evaporation.
Each pair of samples was then touched and felt in a blind box by
two members of a panel of ten panelists and their impressions of
surface dryness were recorded according to a 0-4 grading scale
wherein 0 means a particular pair of samples exhibit equivalent
surface dryness, 1 means that one of a pair of samples is to a low
degree of confidence somewhat dryer than its opposite, 2 means that
one pair of a pair of samples is to a high degree of confidence
somewhat dryer than its opposite, 3 means that one of a pair of
samples is considerably drier than its opposite, and 4 means that
one of a pair of samples is much drier than its opposite. Each pair
of samples was only submitted to two panelists to substantially
eliminate any effect of continued handling of the apparent surface
dryness.
The scores as outlined above were then statistically manipulated to
minimize effects due to differences in human sensitivity and any
tendency of panelists to be biased according to the order in which
the samples were touched or for other reasons. The result of the
statistical manipulation was a group of overall scores for the four
structures wherein the structure designated N (the structure
subjected to pattern densification in accordance with the present
invention) was taken as the standard and given a score of 0, i.e.,
the structure L (the uniform density pad) was scored relative to
structure N. The score was expressed in the form of a yardstick
which corresponds to the smallest significant difference in grade.
A net score difference of 1.0 yardsticks represents a difference
which is statistically significant and a 95 percent level of
confidence. A difference less than 1.0 yardsticks indicates that no
significant exists between samples up to 95 percent confidence
level. The sample L achieved a net score of -2.5 yardsticks
indicating that the sample N which had been subjected to the
pattern densification of the present invention did, to a high
degree of confidence exhibit a skin dryness impression
substantially higher than that of the uniform density product
sample L. A difference of 2.5 yardsticks indicates a clearly
significant difference at the 95 percent level of confidence.
EXAMPLE 2
Unwet samples of the diaper structures referred to in Example 1
were submitted to a similar panel of ten panelists and their
impressions of softness were recorded according to the same 0-4
grading scale. The resultant scores were then statistically
manipulated as described in accordance with Example 1 and the net
score yielded a result of -2.5 yardsticks for the sample L (uniform
density air-felt) relative the sample N (subjected to pattern
densification) on the basis of softness impression indicating that
the diaper structure incorporating the pattern densified air-felt
of the present invention exhibited a clearly significant difference
at the 95 percent level of confidence that the pattern densified
structure exhibited a substantially improved softness impression
over the similar weight basis structure of generally uniform
density.
EXAMPLE 3
To substantiate that a substantial percentage of the area of the
air-felt pad must be subjected to densification to provide
significant wicking, a series of sample diapers were prepared
having tufted air-felt pads subjected to varying percentages of
densification and tests were run, the object of which was to
determine the amount of moisture retained at the point of liquid
loading and at various distances therefrom. Sample 1 was a diaper
having an air-felt pad that had not been subjected to any pattern
densification, i.e., 0 percent densified. Sample 2 was a diaper
prepared having an air-felt pad subjected to pattern densification
extending over 30 percent of the area. Sample 3 was a diaper
prepared having an air-felt pad subjected to pattern densification
over 50 percent of the area. Sample 4 was a diaper having an
air-felt pad subjected to pattern densification over 70 percent of
the area and sample 5 was a diaper having an air-felt pad which had
been compressed or densified over the entire 100 percent. For each
of samples 2, 3, and 4, the densification pattern was as generally
indicated in FIG. 1 of the drawing, in each case utilizing 9/16
inch diameter undensified circular tufts and the densification was
done in a dry state.
Each of the pads then had added to it at its center a quantity of
water providing for 3X loading thereof. By 3X loading is meant a
quantity of test liquid equal to three times the weight of the
absorbent pad structure. This measured quantity of liquid was then
poured onto the center of each diaper and approximately 30 minutes
was allowed for absorption and wicking thereof. At the end of the
30 minute period, the diapers were sectioned into a center strip 3
inches wide, i.e., by cutting 11/2 inches to each side of the
centerline and the remainder of the diaper was then sectioned into
2 inch wide strips. The liquid loading, i.e., weight of water per
weight of cellulose for each strip was then determined. To
compensate for crosswise variations of the diaper, the values
obtained on either side of the centerline at the same distance were
averaged. Results are tabulated below:
Liquid Loading (grams of liquid/grams of cellulose) At Varying
Distances from Centerline Sample No. Centerline at 2.5" at 4.5" at
6.75" ______________________________________ 1 6.8 5.5 1.75 0.1 2
4.75 4.05 2.75 1.1 3 4.8 4.1 2.9 0.75 4 4.7 4.25 2.95 1.1 5 5.15
4.4 2.9 0.75 ______________________________________
Accordingly, it was determined that any densification of 30 percent
or higher of the area resulted in substantially increased wicking
outwardly from the center and the wicking capabilities were not
significantly affected by the percentage of densification over 30
percent.
EXAMPLE 4
To further define the lower limit of percentage area densified
which would produce significant wicking, an additional series of
tests was run, utilizing the same procedure set forth in Example 3
above, utilizing a pattern densification which, however, was not
bilateral but, rather, comprised densification of the diaper pad
along 5/16 inch wide densified transversely extending areas with
the spacing between the densified regions being varied to provide
differing percentage area densification.
Sample 1 was, again, completely undensified, i.e., 0 percent.
Sample 2 was densified over 10 percent of the area, sample 4 was
densified over 30 percent of the area, sample 5 was densified over
50 percent of the area and sample 6 was completely densified, i.e.,
100 percent densified. Results are tabulated below:
Sample 1 6.8 5.5 1.75 .1 Sample 2 6.55 4.6 1.95 0.7 Sample 3 5.3
4.75 2.5 1.0 Sample 4 5.35 4.7 2.7 0.7 Sample 5 5.0 4.4 3.0 1.0
Sample 6 5.1 4.4 2.9 .7
From the results tabulated, it is apparent that 10 percent
densification is not affected to produce substantial wicking from
the central region but, above 20 percent densified area, effective
wicking occurs.
EXAMPLE 5
To substantiate that the softness impression was a function of the
percentage area densified and to determine the effective limits
thereof, sample diapers were prepared having differing percentages
of area densified surrounding undensified and generally circular
regions or turfts of 9/16 inch diameter in the pattern shown and
illustrated generally in FIG. 1 and submitted to expert panels for
testing. Additionally, samples were prepared having straight line
pattern densification as described above in Example 4 and also
submitted for softness comparison to the expert panel. Sample 1 was
completely undensified. Sample 2 was densified in accordance with
the pattern of FIG. 1 with 30 percent densification. Sample 3 was
pattern densified in the pattern of FIG. 1 over 50 percent of the
area. Sample 4 was fully densified, i.e., over 100 percent of the
area. Sample 5 was pattern densified in the straight line pattern
described above over 10 percent of the area. Sample 6 was pattern
densified in the straight line pattern described above over 20
percent of the area. Sample 7 was pattern densified in the straight
line pattern defined above over 50 percent of the area.
The samples were paired and presented in pairs to the panelists in
blind boxes and the panelists assigned a softness score of 0-4 to
each pair using the criteria described in Example 1 above. Each
sample was assigned a separate score based upon the impression of
the panelist. For example, if in comparing two samples a panelist
decided that one sample was, to a high degree of confidence
somewhat softer than the other sample, the sample found softer
would receive a score of +2 and the other sample a score of -2. All
scores received by a sample were then added and divided by a factor
equal to the product of the number of panelists times the number of
samples to provide a comparative softness grade. Results are
tabulated below, the higher softness grade indicated increased
softness impression.
______________________________________ Sample Softness Grade
______________________________________ 1 1.0 2 0.7 3 0.1 4 -0.03 5
-0.31 6 -0.31 7 -0.10 ______________________________________
From the results tabulated, it is apparent that the pattern
densification of the general pattern shown and illustrated in FIG.
1 is substantially softer than straight line pattern densification
of the same area and, in addition, that pattern densification in
excess of approximately 50 percent results in only a very small
change in softness impression. Further, pattern densification of
less than approximately 30 percent in the pattern shown illustrated
in FIG. 1 has very small adverse affect on overall softness and
that over 50 percent there was already a significant decrease in
overall softness approaching that of complete densification.
EXAMPLE 6
To substantiate that the improvement in surface dryness impression
noted at percentage area densifications less than 50 percent were,
in fact, valid indicators of objective surface dryness, a further
test was run, the object of which was to determine the surface
dryness of a diaper structure utilizing the pattern densified pads
of the present invention, objective basis. A series of test pads
were preprepared of 4 inch by 4 inch size comprising a pattern
densified air-felt pad are disposed between a top sheet and back
sheet as in a diaper structure. Sample 1 was a pad wherein the
air-felt was undensified, i.e., 0 percent densified. Sample 2 was a
pad having 5/16 inch wide linear densification over 10 percent of
the area. Sample 3 was a pad having 5/16 inch wide linear
densification over 20 percent of the area. Sample 4 was a pad
having 5/16 inch wide linear densification over 30 percent of the
area. Sample 5 was a tufted pad having 9/16 inch diameter
undensified tufts and densified over 30 percent of the area. Sample
6 was a pad having 5/16 inch wide linear densification over 50
percent of the area. Sample 7 was a tufted pad having 9/16 inch
diameter undensified regions and densified over 50 percent of the
area. Sample 8 was a tufted pad having 1 1/16 inch diameter
undensified tufts and densified over 50 percent of the area. Sample
9 was densified over 100 percent of the area.
Each of the samples was placed on a flat surface and a two inch
diameter flat bottomed cup having a plurality of spaced apart
apertures in the bottom was disposed on top of each sample. A
measured quantity of test liquid equal to three times the weight of
the pad was then added to the cup and allowed to disperse into the
pad through the apertured bottom. After a wait of three minutes,
two plies of previously weighed filter paper were placed on each
sample and loaded with a two inch diameter weight applying a
loading of 0.5 pounds per square inch to the filter paper. After a
wait of two minutes, the filter paper was reweighed and the
additional weight thereof due to absorbed liquid was noted. The
increase in weights are tabulated below.
______________________________________ Sample No. Increase in
Weight in Grams ______________________________________ 1 1.96 2
1.88 3 1.82 4 1.69 5 1.40 6 1.14 7 1.03 8 1.53 9 .66
______________________________________
The results tabulated, it is apparent that increased densified area
does result in improved surface dryness; that a tufted pattern is a
notable improvement over a straight densified pattern and that over
50 percent densification provides only very small increases in
surface dryness. The test further indicated that a 9/16 inch
diameter tuft was substantially more effective in reducing surface
dryness than a 1 1/16 inch diameter tuft.
Accordingly, the examples above indicated that surface dryness
characteristics established are 20 percent area pattern
densification as the lower limit for effective wicking and that 20
percent was effective to produce a satisfactory surface dryness
impression. The tests also indicated that higher than 50 percent of
area densification was not effective in a further increasing
surface. Further, the softness test indicated that 50 percent
pattern densification was the approximate upper limit to acceptable
softness impression and that 50 percent and above marked
deterioration in softness and loss of stability occurred. Further,
the tests indicated that although an overall area densification
range of approximately 20 to 50 percent was acceptable, that
preferably a pattern densification within the range of 30 to 40
percent was preferable.
While the invention has been described, disclosed, illustrated and
shown in terms of an embodiment or modification which has assumed
in practice, the scope of the invention should not be deemed to be
limited by the precise embodiment or modifications herein
described, disclosed, illustrated or shown, such other embodiments
or modifications as may be suggested to those having the benefit of
the teachings herein be intent to be reserved especially as their
fall within in the scope and spirit of the claims here
appended.
* * * * *