Note: Descriptions are shown in the official language in which they were submitted.
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SOFT ABSORBENT SHEETS,
STRUCTURING FABRICS FOR MAKING SOFT ABSORBENT SHEETS,
AND METHODS OF MAKING SOFT ABSORBENT SHEETS
CLAIM FOR PRIORITY
This application is based on United States Non-Provisional Application No.
15/175,949,
filed June 7, 2016, and is also based on United States Non-Provisional
Application No.
15/371,773, filed December 7, 2016. The priorities of the foregoing
applications are hereby
claimed and their disclosures incorporated herein by reference.
BACKGROUND
Field of the Invention
Our invention relates to paper products such as absorbent sheets. Our
invention also relates
to methods of making paper products such as absorbent sheets, as well as to
structuring
fabrics for making paper products such as absorbent sheets.
Related Art
The use of fabrics is well known in the papermaking industry for imparting
structure to paper
products. More specifically, it is well known that a shape can be provided to
paper products
by pressing a malleable web of cellulosic fibers against a fabric and then
subsequently drying
the web. The resulting paper products are thereby formed with a molded shape
corresponding to the surface of the fabric. The resulting paper products also
thereby have
characteristics resulting from the molded shape, such as a particular caliper
and absorbency.
As such, a myriad of structuring fabrics has been developed for use in
papermaking processes
to provide products with different shapes and characteristics. And, fabrics
can be woven into
a near limitless number of patterns for potential use in papermaking
processes.
One important characteristic of many absorbent paper products is
softness¨consumers want,
for example, soft paper towels. Many techniques for increasing the softness of
paper
products, however, have the effect of reducing other desirable properties of
the paper
products. For example, calendering basesheets as part of a process for
producing paper
towels can increase the softness of the resulting paper towels, but
calendering also has the
effect of reducing the caliper and absorbency of the paper towels. On the
other hand, many
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techniques for improving other important properties of paper products have the
effect of
reducing the softness of the paper products. For example, using wet and dry
strength resins
in a papermaking process can improve the underlying strength of paper
products, but wet and
dry strength resins also reduce the perceived softness of the products.
For these reasons, it is desirable to make softer paper products, such as
absorbent sheets.
And, it is desirable to be able to make such softer absorbent sheets through
manipulation of a
structuring fabric used in the process of making the absorbent sheets.
SUMMARY OF THE INVENTION
According to one aspect, our invention provides an absorbent sheet of
cellulosic fibers. The
absorbent cellulosic sheet includes a plurality of projected regions
projecting from the
absorbent sheet, wherein the projected regions include folds that are curved
relative to the
machine direction of the absorbent sheet. Ends of the curved folds are on
opposite sides of
the projected regions and such that one of the ends of each of the curved
folds is positioned
downstream from the other end of the curved folds in the machine direction of
the absorbent
sheet. Apexes of the curved folds are positioned downstream in the machine
direction of the
absorbent sheet. Further, connecting regions connecting the projected regions
of the
absorbent sheet.
According to another aspect, our invention provides an absorbent cellulosic
sheet. A
plurality of projected regions project from the absorbent sheet, wherein the
projected regions
include folds that are curved relative to the machine direction of the
absorbent sheet. Ends of
the curved folds are on opposite sides of the projected regions, and the
curved folds have a
radius of curvature of about 0.5 mm to about 2.0 mm. Further, connecting
regions
connecting the projected regions of the absorbent sheet.
According to a further aspect, our invention provides a papermaking web. The
papermaking
web comprises a plurality of projected regions projecting from the papermaking
web,
wherein the projected regions include folds that are curved relative to a
machine direction of
the absorbent sheet, with ends of the curved folds being on opposite sides of
the projected
regions and such that one of the ends of each of the curved folds is
positioned downstream
from the other end of the curved folds in the machine direction of the
papermaking web.
Apexes of the curved folds are positioned downstream in the machine direction
of the
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papermaking web. Connecting regions form a network connecting the projected
regions of
the papermaking web.
According to yet another aspect, our invention provides a method of making a
fabric-creped
absorbent cellulosic sheet. The method includes compactively dewatering a
papermaking
furnish to form a web. The method also includes creping the web under pressure
in a creping
nip between a transfer surface and a structuring fabric. The structuring
fabric includes
knuckles formed on warp yarns of the structuring fabric, with the knuckles
being positioned
along lines that are angled relative to the machine direction of the fabric,
wherein the angle of
lines relative to the machine direction is between about 100 and about 30 .
Further, the
method includes a step of drying the web to form the absorbent cellulosic
sheet.
According to yet another aspect, our invention provides an absorbent
cellulosic sheet that
includes a plurality of projected regions projecting from the absorbent sheet,
with the
projected regions including folds that are curved in the machine direction of
the absorbent
sheet, and with ends of the curved folds being on opposite sides of the
projected regions. The
absorbent sheet has a normalized fold curvature ratio that is less than about
4. The absorbent
sheet also includes connecting regions forming a network connecting the
projected regions of
the absorbent sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic diagram of a papermaking machine configuration that
can be used in
conjunction with our invention.
Figure 2 is a top view of a structuring fabric for making paper products
according to an
embodiment of our invention.
Figures 3A-3F indicate characteristics of structuring fabrics according to
embodiments of our
invention and characteristics of comparison structuring fabrics.
Figures 4A-4E are photographs of absorbent sheets according to embodiments of
our
invention.
Figure 5 is an annotated version of the photograph shown in Figure 4E.
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Figures 6A and 6B are cross-sectional views of a portion of an absorbent sheet
according to
an embodiment of our invention and a portion of a comparison absorbent sheet,
respectively.
Figures 7A and 7B show laser scans for determining the profile of portions of
absorbent
sheets according to embodiments of our invention.
Figure 8 indicates characteristics of structuring fabrics according to
embodiments of our
invention and a comparison structuring fabric.
Figure 9 shows the characteristics of basesheets that were made using the
structuring fabrics
having the characteristics shown in Figure 8.
Figures 10A-10D indicate characteristics of still further structuring fabrics
according to
embodiments of our invention.
Figures 11A-11E are photographs of absorbent sheets according to embodiments
of our
invention.
Figures 12A-12E are photographs of further absorbent sheets according to
embodiments of
our invention.
Figure 13 indicates characteristics of structuring fabrics according to
embodiments of our
invention and a comparison structuring fabric.
Figure 14 shows a measurement of a profile along one of the warp yarns of a
structuring
fabric according to an embodiment of our invention.
Figure 15 is a chart showing fabric crepe percentage versus caliper for
basesheets made with
a fabric according to an embodiment of our invention and a comparative fabric.
Figure 16 is a chart showing fabric crepe percentage versus SAT capacity for
basesheets
made with a fabric according to an embodiment of our invention and a
comparative fabric.
Figure 17 is a chart showing fabric crepe percentage versus caliper for
basesheets made with
different furnishes and a fabric according to an embodiment of our invention.
Figure 18 is a chart showing fabric crepe percentage versus SAT capacity for
basesheets
made with different furnishes and a fabric according to an embodiment of our
invention.
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Figure 19 is a chart showing fabric crepe percentage versus void volume for
basesheets made
with a fabric according to an embodiment of our invention and a comparative
fabric.
Figures 20A and 20B are soft x-ray images of an absorbent sheet according to
an
embodiment of our invention.
Figures 21A and 21B are soft x-ray images of an absorbent sheet according to
another
embodiment of our invention.
Figures 22A-22E are photographs of absorbent sheets according to further
embodiments of
our invention.
Figures 23A and 23B are photographs of an absorbent sheet according to an
embodiment of
our invention and a comparison absorbent sheet.
Figure 24A and 24B are photographs of cross sections of the absorbent sheets
shown in
Figures 23A and 23B, respectively.
Figures 25A and 25B indicate characteristics of further structuring fabrics
according to
embodiments of our invention.
Figure 26 is a detailed view of a pressure imprint of one of the structuring
fabrics having the
characteristics shown in Figure 25B.
Figure 27A-27C show fold formations around the knuckles in a structuring
fabric according
to an embodiment of our invention and around knuckles in comparative
structuring fabrics.
Figures 28A-28E are photographs of further absorbent sheets according to
embodiments of
-- our invention.
Figure 29 is photograph of an absorbent sheet according to an embodiment of
our invention
with annotation lines for determining aspects of the fabric.
Figures 30A and 30B are photographs of an absorbent sheet according to our
invention and a
comparison absorbent sheet, respectively.
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DETAILED DESCRIPTION OF THE INVENTION
Our invention relates to paper products such as absorbent sheets and methods
of making
paper products such as absorbent sheets. Absorbent paper products according to
our
invention have outstanding combinations of properties that are superior to
other absorbent
paper products that are known in the art. In some specific embodiments, the
absorbent paper
products according to our invention have combinations of properties
particularly well suited
for absorbent hand towels, facial tissues, or toilet paper.
The term "paper product," as used herein, encompasses any product
incorporating
papermaking fibers having cellulose as a major constituent. This would
include, for example,
products marketed as paper towels, toilet paper, facial tissue, etc.
Papermaking fibers include
virgin pulps or recycled (secondary) cellulosic fibers, or fiber mixes
comprising cellulosic
fibers. Wood fibers include, for example, those obtained from deciduous and
coniferous
trees, including softwood fibers, such as northern and southern softwood kraft
fibers, and
hardwood fibers, such as eucalyptus, maple, birch, aspen, or the like.
Examples of fibers
suitable for making the products of our invention include non-wood fibers,
such as cotton
fibers or cotton derivatives, abaca, kenaf, sabai grass, flax, esparto grass,
straw, jute hemp,
bagasse, milkweed floss fibers, and pineapple leaf fibers.
"Furnishes" and like terminology refers to aqueous compositions including
papermaking
fibers, and, optionally, wet strength resins, debonders, and the like, for
making paper
products. A variety of furnishes can be used in embodiments of our invention,
and specific
furnishes are disclosed in the examples discussed below. In some embodiments,
furnishes
are used according to the specifications described in commonly-assigned U.S.
Patent No.
8,080,130 (the disclosure of which is incorporated by reference in its
entirety). The furnishes
in this patent include, among other things, cellulosic long fibers having a
coarseness of at
least about 15.5 mg/100 mm. Examples of furnishes are also specified in the
examples
discussed below.
As used herein, the initial fiber and liquid mixture that is dried to a
finished product in a
papermaking process will be referred to as a "web" and/or a "nascent web." The
dried,
single-ply product from a papermaking process will be referred to as a
"basesheet." Further,
the product of a papermaking process may be referred to as an "absorbent
sheet." In this
regard, an absorbent sheet may be the same as a single basesheet.
Alternatively, an absorbent
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sheet may include a plurality of basesheets, as in a multi-ply structure.
Further, an absorbent
sheet may have undergone additional processing after being dried in the
initial basesheet
forming process in order to form a final paper product from a converted
basesheet. An
"absorbent sheet" includes commercial products marketed as, for example, hand
towels.
When describing our invention herein, the terms "machine direction" (MD) and
"cross
machine direction" (CD) will be used in accordance with their well-understood
meaning in
the art. That is, the MD of a fabric or other structure refers to the
direction that the structure
moves on a papermaking machine in a papermaking process, while CD refers to a
direction
crossing the MD of the structure. Similarly, when referencing paper products,
the MD of the
-- paper product refers to the direction on the product that the product moved
on the
papermaking machine in the papermaking process, and the CD of the product
refers to the
direction crossing the MD of the product. In terms of the MD of the paper
product,
"downstream" refers to an area that is formed before an "upstream" area.
Figure 1 shows an example of a papermaking machine 200 that can be used to
make paper
-- products according to our invention. A detailed description of the
configuration and
operation of papermaking machine 200 can be found in commonly-assigned U.S.
Patent No.
7,494,563 ("the '563 patent"), the disclosure of which is incorporated by
reference in its
entirety. Notably, the '563 patent describes a papermaking process that does
not use through
air drying (TAD). The following is a brief summary of a process for forming an
absorbent
-- sheet using papermaking machine 200.
The papermaking machine 200 is a three-fabric loop machine that includes a
press section
100 in which a creping operation is conducted. Upstream of the press section
100 is a
forming section 202. The forming section 202 includes headbox 204 that
deposits an
aqueous furnish on a forming wire 206 supported by rolls 208 and 210, thereby
forming an
-- initial aqueous cellulosic web 116. The forming section 202 also includes a
forming roll 212
that supports a papermaking felt 102 such that web 116 is also formed directly
on the felt
102. A felt run 214 extends about a suction turning roll 104 and then to a
shoe press section
216 wherein the web 116 is deposited on a backing roll 108. The web 116 is wet-
pressed
concurrently with the transfer of the web 116 to the backing roll 108, which
carries the web
116 to a creping nip 120. In other embodiments, however, instead of being
transferred on the
backing roll 108, the web 116 by be transferred from the felt run 214 onto an
endless belt in a
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dewatering nip, with the endless belt then carrying the web 116 to the creping
nip 120. An
example of such a configuration can be seen in U.S. Patent No. 8,871,060,
which is
incorporated by reference herein in its entirety.
The web 116 is transferred onto the structuring fabric 112 in the creping nip
120, and then
vacuum drawn by vacuum molding box 114. After this creping operation, the web
116 is
deposited on a Yankee dryer 218 in another press nip 217 using a creping
adhesive that is
applied to the surface of the Yankee dryer 218. The web 116 is dried on Yankee
dryer 218,
which is a heated cylinder, and the web 116 is also dried by high jet velocity
impingement air
in the hood around the Yankee dryer 218. As the Yankee dryer 218 rotates, the
web 116 is
peeled from the dryer 218 at position 220. The web 116 may then be
subsequently wound on
a take-up reel (not shown). The reel may be operated slower than the Yankee
dryer 218 at
steady-state in order to impart a further crepe to the web. Optionally, a
creping doctor blade
222 may be used to conventionally dry-crepe the web 116 as it is removed from
the Yankee
dryer 218.
In the creping nip 120, the web 116 is transferred onto the top side of the
structuring fabric
112. The creping nip 120 is defined between the backing roll 108 and the
structuring fabric
112, with the structuring fabric 112 being pressed against the backing roll
108 by a creping
roll 110. Because the web 116 still has a high moisture content when it is
transferred to the
structuring fabric 112, the web is deformable such that portions of the web
can be drawn into
pockets formed between the yarns that make up the structuring fabric 112. (The
pockets of
structuring fabrics will be described in detail below.) In particular
papermaking processes,
the structuring fabric 112 moves more slowly than does the papermaking felt
102. Thus, the
web 116 is creped as it is transferred onto the structuring fabric 112.
An applied suction from vacuum molding box 114 may also aid in drawing the web
116 into
pockets in the surface of the structuring fabric 112, as will be described
below. When
traveling along the structuring fabric 112, the web 116 reaches a highly
consistent state with
most of the moisture having been removed. The web 116 is thereby more or less
permanently imparted with a shape by the structuring fabric 112, with the
shape including
domed regions where the web 116 is drawn into the pockets of the structuring
fabric 112.
Basesheets made with papermaking machine 200 may also be subjected to further
processing,
as is known in the art, in order to convert the basesheets into specific
products. For example,
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the basesheets may be embossed, and two basesheets can be combined into multi-
ply
products. The specifics of such converting processes are well known in the
art.
Using the process described in the aforementioned '563 patent, the web 116 is
dewatered to
the point that it has a higher consistency when transferred onto the top side
of the structuring
fabric 112 as compared to an analogous operation in other papermaking
processes, such as a
TAD process. That is, the web 116 is compactively dewatered so as to have from
about 30
percent to about 60 percent consistency (i.e., solids content) before entering
the creping nip
120. In the creping nip 120, the web 116 is subjected to a load of about 30
pounds per linear
inch (PLI) to about 200 PLI. Further, there is a speed differential between
the backing roll
108 and the structuring fabric 112. This speed differential is referred to as
the fabric creping
percentage, and may be calculated as:
Fabric Crepe % = Si/S2 ¨ 1
where Si is the speed of the backing roll 108 and Sz is the speed of the
structuring fabric 112.
In particular embodiments, the fabric crepe percentage, or "creping ratio,"
can be anywhere
from about 3% to about 100%. This combination of web consistency, speed
differential
occurring at the creping nip 120, the pressure employed at the creping nip
120, and the
structuring fabric 112 and creping nip 120 geometry act to rearrange the
cellulose fibers
while the web 116 is still pliable enough to undergo structural change. In
particular, without
intending to be bound by theory, it is believed that the slower forming
surface speed of the
structuring fabric 112 causes the web 116 to be substantially molded into
openings in the
structuring fabric 116, with the fibers being realigned in proportion to the
creping ratio.
While a specific process has been described in conjunction with the
papermaking machine
200, those skilled in the art will appreciate that our invention disclosed
herein is not limited
to the above-described papermaking process. For example, as opposed to the non-
TAD
process described above, our invention could be related to a TAD papermaking
process. An
example of a TAD papermaking process can be seen in U.S. Patent No. 8,080,130,
the
disclosure of which is incorporated by reference in its entirety.
Figure 2 is a drawing showing details of a portion of the web contacting side
of a structuring
fabric 300 that has a configuration for forming paper products according to an
embodiment of
our invention. The structuring fabric 300 includes warp yarns 302 that run in
the machine
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direction (MD) when the fabric is used in a papermaking process, and weft
yarns 304 that run
in the cross machine direction (CD). The warp and weft yarns 302 and 304 are
woven
together so as to form the body of the structuring fabric 300. The web-
contacting surface of
the structuring fabric 300 is formed by knuckles (two of which are outlined in
Figure 2 and
labeled as 306 and 310), which are formed on the warp yarns 302, but no
knuckles are
formed on the weft yarns 304. It should be noted, however, that while the
structuring fabric
300 shown in Figure 2 only has knuckles on the warp yarns 302, our invention
is not limited
to structuring fabrics that only have warp knuckles, but rather, includes
fabrics that have both
warp and weft knuckles. Indeed, fabrics with only warp knuckles and fabrics
with both warp
and weft knuckles will be described in detail below.
The knuckles 306 and 310 in the structuring fabric 300 are in a plane that
makes up the
surface that the web 116 contacts during a papermaking operation. Pockets 308
(one of
which is shown as the dotted outlined area in Figure 2) are defined in the
areas between the
knuckles 306 and 310. Portions of the web 116 that do not contact the knuckles
306 and 310
are drawn into the pockets 308 as described above. It is the portions of the
web 116 that are
drawn into the pockets 308 that result in domed regions that are found in the
resulting paper
products.
Those skilled in the art will appreciate the significant length of warp yarn
knuckles 306 and
310 in the MD of structuring fabric 300, and will further appreciate that the
fabric 300 is
configured such that the long warp yarn knuckles 306 and 310 delineate long
pockets in the
MD. In particular embodiments of our invention, the warp yarn knuckles 306 and
310 have a
length of about 2 mm to about 6 mm. Most structuring fabrics known in the art
have shorter
warp yarn knuckles (if the fabrics have any warp yarn knuckles at all). As
will be described
below, the longer warp yarn knuckles 306 and 310 provide for a larger contact
area for the
web 116 during the papermaking process, and, it is believed, might be at least
partially
responsible for the increased softness seen in absorbent sheets according to
our invention, as
compared to absorbent sheets with conventional, shorter warp yarn knuckles.
To quantify the parameters of the structuring fabrics described herein, the
fabric
characterization techniques described in the commonly-assigned U.S. Patent
Application
Publication Nos. 2014/0133734; 2014/0130996; 2014/0254885, and 2015/0129145
(hereafter
referred to as the "fabric characterization publications") can be used. The
disclosures of the
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fabric characterization publications are incorporated by reference in their
entirety. Such
fabric characterization techniques allow for parameters of a structuring
fabric to be easily
quantified, including knuckle lengths and widths, knuckle densities, pocket
areas, pocket
densities, pocket depths, and pocket volumes.
Figures 3A-3E indicate some of the characteristics of structuring fabrics made
according to
embodiments of our invention, which are labeled as Fabrics 1-15. Figure 3F
also shows
characteristics of conventional structuring fabrics, which are labeled as
Fabrics 16 and 17.
Structuring fabrics of the type shown in Figures 3A-3F can be made by numerous
manufacturers, including Albany International of Rochester, New Hampshire, and
Voith
GmbH of Heidenheim, Germany. Fabrics 1-15 have long warp yarn knuckle fabrics
such that
the vast majority of the contact area in Fabrics 1-15 comes from the warp yarn
knuckles, as
opposed to weft yarn knuckles (if the fabrics have any weft yarn knuckles at
all). Fabrics 16
and 17, which have shorter warp yarn knuckles, are provided for comparison.
All of the
characteristics shown in Figures 3A-3F were determined using the techniques in
the
aforementioned fabric characterization publications, particularly, using the
non-rectangular,
parallelogram calculation methods that are set forth in the fabric
characterization
publications. Note that the indications of "N/C" in Figures 3A-3F mean that
the particular
characteristics were not determined.
The air permeability of a structuring fabric is another characteristic that
can influence the
properties of paper products made with the structuring fabric. The air
permeability of a
structuring fabric is measured according to well-known equipment and tests in
the art, such as
Frazier Differential Pressure Air Permeability Measuring Instruments by
Frazier Precision
Instrument Company of Hagerstown, Maryland. Generally speaking, the long warp
knuckle
structuring fabrics used to produce paper products according to our invention
have a high
amount of air permeability. In a particular embodiment of our invention, the
long warp
knuckle structuring fabric has an air permeability of about 450 CFM to about
1000 CFM.
Figures 4A-4E are photographs of absorbent sheets made with long warp knuckle
structuring
fabrics, such as those characterized in Figures 3A-3E. More specifically,
Figures 4A-4E
show the air side of the absorbent sheets, that is, the side of the absorbent
sheets that
contacted the structuring fabric during the process of forming the absorbent
sheets. Thus, the
distinct shapes that are imparted to the absorbent sheets through contact with
the structuring
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fabrics, including domed regions projecting from the shown side of the
absorbent sheet, can
be seen in Figures 4A-4E. Note that the MD of the absorbent sheets is shown
vertically in
these figures.
Specific features of the absorbent sheet 1000 are annotated in Figure 5, which
is based on the
photograph shown as Figure 4E. The absorbent sheet 1000 includes a plurality
of
substantially rectangular-shaped domed regions, some of which are outlined and
labeled
1010, 1020, 1030, 1040, 1050, 1060, 1070, and 1080 in Figure 5. As explained
above, the
domed regions 1010, 1020, 1030, 1040, 1050, 1060, 1070, and 1080 correspond to
the
portions of the web that were drawn into the pockets of the structuring fabric
during the
process of forming the absorbent sheet 1000. Connecting regions, some of which
are labeled
1015, 1025, and 1035 in Figure 5, form a network interconnecting the domed
regions. The
connecting regions generally correspond to portions of the web that were
formed in the plane
of the knuckles of the structuring fabric during the process of forming the
absorbent sheet
1000.
Those skilled in the art will immediately recognize several features of the
absorbent sheets
shown in Figures 4A-4E and 5 that are different than conventional absorbent
sheets. For
instance, all of the domed regions include a plurality of indented bars formed
into the tops of
the domed regions, with the indented bars extending across the domed regions
in the CD of
the absorbent sheets. Some of these indented bars are outlined and labeled
1085 in Figure 5.
Notably, almost all of the domed regions have three such indented bars, with
some of the
domed regions having four, five, six, seven, or even eight indented bars. The
number of
indented bars can be confirmed using laser scan profiling (described below).
Using such
laser scan profiling, it was found that in a particular absorbent sheet
according to an
embodiment of our invention, there are, on average (mean), about six indented
bars per
domed region.
Without being limited by theory, we believe that the indented bars seen in the
absorbent
sheets shown in Figure 4A-4E and 5 are formed when the web is transferred onto
a
structuring fabric with the configurations described herein during a
papermaking process as
described herein. Specifically, when a speed differential is used for creping
the web as it is
transferred onto the structuring fabric, the web "plows" onto the knuckles of
the structuring
fabric and into the pockets between the knuckles. As a result, folds are
created in the
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structure of the web, particularly in the areas of the web that are moved into
the pockets of
the structuring fabric. An indented bar is thus formed between two of such
folds in the web.
Because of the long MD pockets in the long warp yarn knuckle structuring
fabrics described
herein, the plowing/folding effect takes place multiple times over a portion
of a web that
spans a pocket in the structuring fabric. Thus, multiple indented bars are
formed in each of
the domed regions of absorbent sheets made with the long warp knuckle
structuring fabrics
described herein.
Again, without being limited by theory, we believe that the indented bars in
the domed
regions may contribute to an increased softness that is perceived in the
absorbent sheets
according to our invention. Specifically, the indented bars provide a more
smooth, flat plane
being perceived when the absorbent sheet is touched, as compared to absorbent
sheets having
conventional domed regions. The difference in perceptional planes is
illustrated in Figures
6A and 6B, which are drawings showing cross sections of an absorbent sheet
2000 according
to our invention and a comparison sheet 3000, respectively. In absorbent sheet
2000, the
domed regions 2010 and 2020 include indented bars 2080, with ridges being
formed between
the indented bars 2080 (the ridges/indents correspond to the folds in the web
during the
papermaking process as described above). As a result of the small indented
bars 2080 and
plurality of ridges around the indented bars 2080, flat, smooth perceived
planes P1 (marked
with dotted lines in Figure 6A) are formed. These flat, smooth planes P1 are
sensed when the
absorbent sheet 2000 is touched. We further believe that the users cannot
detect the small
discontinuities of the indented bars 2080 in the surfaces of the domed regions
2010 and 2020,
nor can users detect the short distance between the domed regions 2010 and
2020. Thus, the
absorbent sheet 2000 is perceived as having a smooth, soft surface. On the
other hand, the
perceived planes P2 have a more rounded shape with the conventional domes 3010
and 3020
in comparison sheet 3000, as shown in Figure 6B, and the conventional domes
3010 and
3020 are spaced apart. It is believed that because the perceived planes P2 of
the conventional
domes 3010 and 3020 are spaced a significant distance from each other, the
comparison sheet
3000 is perceived as less smooth and soft compared to the perceived planes P1
found in the
domed regions 2010 and 2020 with the indented bars 2080.
Those skilled in the art will appreciate that, due to the nature of a
papermaking process, not
every domed region in an absorbent sheet will be identical. Indeed, as noted
above, domed
regions of an absorbent sheet according to our invention might have different
numbers of
13
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indented bars. At the same time, a few of the domed regions observed in any
particular
absorbent sheet of our invention might not include any indented bars. This
will not affect the
overall properties of the absorbent sheet, however, as long as a majority of
the domed regions
includes the indented bars. Thus, when we refer to an absorbent sheet as
having domed
-- regions that include a plurality of indented bars, it will be understood
that that absorbent sheet
might have a few domed regions with no indented bars.
The lengths and depths of the indented bars in absorbent sheets, as well as
the lengths of the
domed regions, can be determined from a surface profile of a domed region that
is made
using laser scanning techniques, which are well known in the art. Figures 7A
and 7B show
-- laser scan profiles across domed regions in two absorbent sheets according
to our invention.
The peaks of the laser scan profiles are the areas of the domes that are
adjacent to the
indented bars, while the valleys of the profiles represent the bottoms of the
indented bars.
Using such laser scan profiles, we have found that the indented bars extend to
a depth of
about 45 microns to about 160 microns below the tops of the adjacent areas of
the domed
-- regions. In a particular embodiment, the indented bars extend an average
(mean) of about 90
microns below the tops of the adjacent areas of the domed regions. In some
embodiments,
the domed regions extend a total of about 2.5 mm to about 3 mm in length in a
substantially
MD of the absorbent sheets. Those skilled in the art will appreciate that such
lengths in the
MD of the domed regions are greater than the lengths of domed regions in
conventional
-- fabrics, and that the long domed regions are at least partially the result
of the long MD
pockets in the structuring fabrics used to create the absorbent sheets, as
discussed above.
From the laser scan profiles, it can also be seen that the indented bars were
spaced about 0.5
mm apart along the lengths of the domed regions in embodiments of our
invention.
Further distinct features that can be seen in the absorbent sheets shown in
Figures 4A-4E and
-- 5 include the dome regions being bilaterally staggered in the MD such that
substantially
continuous, stepped lines of domed regions extend in the MD of the sheets. For
example,
with reference again to Figure 5, the domed region 1010 is positioned adjacent
to the domed
region 1020, with the two domed regions overlapping in a region 1090.
Similarly, the domed
region 1020 overlaps domed region 1030 in a region 1095. The bilaterally
staggered domed
regions 1010, 1020, and 1030 form a continuous, stepped line, substantially
along the MD of
the absorbent sheet 1000. Other domed regions form similar continuous, stepped
lines in the
MD.
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We believe that the configuration of the elongated, bilaterally staggered
domed regions, in
combination with the indented bars extending across the domed regions, results
in the
absorbent sheets having a more stable configuration. For example, the
bilaterally staggered
domed regions provide for a smooth planar surface on the Yankee side of the
absorbent
sheets, which thereby results in a better distribution of pressure points on
the absorbent sheet.
Note, the Yankee side of an absorbent sheet is the side of the absorbent
sheets that is opposite
to the air side of the absorbent sheets that is drawn into the structuring
fabric during the
papermaking process. In effect, the bilaterally staggered domed regions act
like long boards
in the MD direction that cause the absorbent sheet structure to lay flat. This
effect, resulting
from the combination of bilaterally staggered domed regions and indented bars
will, for
example, cause a web to better lay down on the surface of a Yankee dryer
during a
papermaking process, which results in better absorbent sheets.
Similar to the continuous lines of domed regions, substantially continuous
lines of connecting
regions extend in a stepped manner along the MD of the absorbent sheet 1000.
For example,
connection region 1015, which runs substantially in the CD, is contiguous with
connecting
region 1025, which runs substantially in the CD. Connecting region 1025 is
also contiguous
with connecting region 1035, which runs substantially in the MD. Similarly,
connecting
region 1015 is contiguous with connecting region 1025 and connecting region
1055. In sum,
the MD connecting regions are substantially longer than the CD connecting
regions, such that
lines of stepped, continuous connecting regions can be seen along the
absorbent sheet.
As discussed above, the sizes of the domed regions and the connecting regions
of an
absorbent sheet generally correspond to the pocket and knuckle sizes in the
structuring fabric
used to produce the absorbent sheet. In this regard, we believe that the
relative sizing of the
domed and connecting regions contributes to the softness of absorbent sheets
made with the
fabric. We also believe that the softness is further improved as a result of
the substantially
continuous lines of domed regions and connecting regions. In a particular
embodiment of our
invention, a distance in the CD across the domed regions is about 1.0 mm, and
a distance in
the CD across the MD oriented connecting regions is about 0.5 mm. Further, the
overlap/touching regions between adjacent domed regions in the substantially
continuous
lines are about 1.0 mm in length along the MD. Such dimensions can be
determined from a
visual inspection of the absorbent sheets, or from a laser scan profile as
described above. An
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exceptionally soft absorbent sheet can be achieved when these dimensions are
combined with
the other features of our invention described herein.
In order to evaluate the properties of products according to our invention,
absorbent sheets
were made using Fabric 15 as shown Figure 3E in a papermaking machine having
the general
configuration shown in Figure 1 with a process as described above. For
comparison,
products were made using the shorter warp length knuckle Fabric 17 (that is
also shown in
Figure 3F) under the same process conditions. Parameters used to produce
basesheets for
these trials are shown in TABLE 1.
TABLE 1
Process Variable Location Rate
Furnish: 100 % SHWK to Yankee layer Stratified
65% SHWK
35% SSWK 70% SSWK and 30% SHWKK to middle
and air layers
Refiner Stock Vary as needed
Temporary Wet Stock pumps 3
lb/T
Strength Resin:
FJ98
Starch: Static mixers 8 lb/T
REDIBONDTm 5330A
Crepe Roll Load Crepe Roll 45
PLI
Fabric Crepe Crepe Roll 20%
Reel Crepe Reel 7%
Calender Load Calender Stacks As
needed
Molding Box Vacuum Molding Box
Maximum
The basesheets were converted to produce two-ply glued tissue prototypes.
TABLE 2 shows
the converting specifications for the trials.
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TABLE 2
Conversion Process Gluing
Number of Plies 2
Roll Diameter 4.65 in.
Sheet Count 190
Sheet Length 4.09 in.
Sheet Width 4.05 in.
Roll Compression 18-20%
Emboss Process Following
process of
U.S. Patent No. 6,827,819
(which is incorporated
by reference in its entirety)
Emboss Pattern
Constant/Non-Varying
Sheets formed in the trials with Fabric 15 (i.e., a long warp knuckle fabric)
were found to be
smoother and softer than the sheets formed in the trials with Fabric 17 (i.e.,
a shorter warp
knuckle fabric). Other important properties of the sheets made with Fabric 15,
such as
caliper and bulk, were found to be very comparable to those properties of the
sheets made
with Fabric 17. Thus, it is clear that the basesheets made with the long warp
knuckle Fabric
could potentially be used to make absorbent products that are softer than
absorbent
products with the shorter warp knuckle Fabric 17 without the reduction of
other important
10 properties of the absorbent products.
As described in the aforementioned fabric characterization publications, the
planar
volumetric index (PVI) is a useful parameter for characterizing a structuring
fabric. The PVI
for a structuring fabric is calculated as the contact area ratio (CAR)
multiplied by the
effective pocket volume (EPV) multiplied by one hundred, where the EPV is the
product of
15 the pocket area estimate (PA) and the measured pocket depth. The pocket
depth is most
accurately calculated by measuring the caliper of a handsheet formed on the
structuring fabric
in a laboratory, and then correlating the measured caliper to the pocket
depth. And, unless
otherwise noted, all of the PVI-related parameters described herein were
determined using
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this handsheet caliper measuring method. Further, a non-rectangular,
parallelogram PVI is
calculated as the contact area ratio (CAR) multiplied by the effective pocket
volume (EPV)
multiplied by one hundred, where the CAR and EPV are calculated using a non-
rectangular,
parallelogram unit cell area calculation. In embodiments of our invention, the
contact area of
the structuring long warp knuckle fabric varies between about 25% to about 35%
and the
pocket depth varies between about 100 microns to about 600 microns, with the
PVI thereby
varying accordingly.
Another useful parameter for characterizing a structuring fabric related to
the PVI is a planar
volumetric density index (PVDI) of the structuring fabric. The PVDI of a
structuring fabric
is defined as the PVI multiplied by pocket density. Note that in embodiments
of our
invention, the pocket density varies between about 10 cm-2 to about 47 cm-2.
Yet another
useful parameter of a structuring fabric can be developed by multiplying the
PVDI by the
ratio of the length and width of the knuckles of the fabric, thereby providing
a PVDI-knuckle
ratio (PVDI-KR). For example, a PVDI-KR for a long warp knuckle structuring
fabric as
described herein would be the PVDI of the structuring fabric multiplied by the
ratio of warp
knuckles length in the MD to the warp knuckles width in the CD. As is apparent
from the
variables used to calculate the PVDI and PVDI-KR, these parameters take into
account
important aspects of a structuring fabric (including percentage of contact
area, pocket density,
and pocket depth) that affect shapes of paper products made using the
structuring fabric, and,
hence, the PVDI and PVDI-KR may be indicative of the properties of the paper
products such
as softness and absorbency.
The PVI, PVDI, PVDI-KR, and other characteristics were determined for three
long warp
knuckle structuring fabrics according to embodiments of our invention, with
the results being
shown as Fabrics 18-20 in Figure 8. For comparison, the PVI, PVDI, PVDI-KR,
and other
characteristics were also determined for a shorter warp knuckle structuring
fabric, as is shown
as Fabric 21 in Figure 8. Notably, the PVDI-KRs for Fabrics 18-20 are about 43
to about 50,
which are significantly greater than the PVDI-KR of 16.7 for Fabric 21.
Fabrics 18-21 were used to produce absorbent sheets, and characteristics of
the absorbent
sheets were determined, as shown in Figure 9. The characteristics shown in
Figure 9 were
determined using the same techniques that are described in the aforementioned
fabric
characterization publications. In this regard, the determinations of the
interconnecting
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regions correspond to the warp knuckles on the structuring fabric, and the
dome regions
correspond to the pockets of the structuring fabric. Also, it could again be
seen that the
sheets made from the long warp knuckle Fabrics 18-20 have multiple indented
bars in each
dome region. On the other hand, the domed regions of the absorbent sheet
formed from the
shorter warp knuckle Fabric 21 had, at most, one indented bar, and many of the
domed
regions did not have any indented bars at all.
The sensory softness was determined for the absorbent sheets shown in Figure
9. Sensory
softness is a measure of the perceived softness of a paper product as
determined by trained
evaluators using standardized testing techniques. More specifically, sensory
softness is
measured by evaluators experienced with determining the softness, with the
evaluators
following specific techniques for grasping the paper and ascertaining a
perceived softness of
the paper. The higher the sensory softness number, the higher the perceived
softness. In the
case of the sheets made from Fabrics 18-20, it was found that the absorbent
sheets made with
Fabrics 18-20 were 0.2 to 0.3 softness units higher than the absorbent sheets
made with
Fabric 21. This difference is outstanding. Moreover, the sensory softness was
found to
correlate with the PVDI-KR of the fabrics. That is, the higher the PVDI-KR of
the
structuring fabric, the higher the sensory softness number that was achieved.
Thus, we
believe that PVDI-KR is a good indicator of the softness that can be achieved
in a paper
product made with a process using a structuring fabric, with a higher PVDI-KR
structuring
fabric producing a softer product.
Figures 10A-10D show characteristics of further long-warp knuckle Fabrics 22-
41 according
to various embodiments of our invention, including the PVI, PVDI, and PVDI-KR
for each of
the fabrics. Notably, these structuring fabrics have a wider range of
characteristics than the
structuring fabrics described above. For example, contact lengths of the warp
knuckles of
Fabrics 22-41 ranged from about 2.2 mm to about 5.6 mm. In further embodiments
of our
invention, however, the contact lengths of the warp knuckles may range from
about 2.2 mm
to about 7.5 mm. Note that in the case of Fabrics 22-37 and 41, the pocket
depths were
determined by forming a handsheet on the fabrics and then determining the size
of domes on
the handsheet (the size of the domes corresponding to the size of the pockets,
as described
above). The pocket depths for Fabrics 38-40 were determined using techniques
set forth in
the aforementioned fabric characterization patents.
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Further trials were conducted to evaluate properties of absorbent sheets
according to
embodiments of our invention. In these trials, the Fabrics 27 and 38 were
used. For these
trials, a papermaking machine having the general configuration shown in Figure
1 was used
with a process as described above. Parameters used to produce the basesheets
for these trials
are shown in TABLE 3. Note that an indication of a varying rate means that the
process
variable was varied in different trial runs.
TABLE 3
Process Variable Location Rate
Furnish Lighthouse Recycled Fibers Homogeneous
Refiner Stock No load (22 hp)
Temporary Wet N/A 0
Strength Resin
Starch: Static mixers As needed
REDIBOND TM 5330A
Crepe Roll Load Crepe Roll 30-40 PLI
Fabric Crepe Crepe Roll varying 25%-35%
Reel Crepe Reel 2-4%
Molding Box Vacuum Molding Box Maximum
The basesheets in these trials were converted into unembossed, single-ply
rolls.
Pictures of the absorbent sheets made with Fabric 27 are shown in Figures 11A-
11E and
pictures of the absorbent sheets made with Fabric 38 are shown in Figures 12A-
12E. As is
apparent from Figures 11A-11E and 12A-12E, the domed regions of the absorbent
sheets
include a plurality of indented bars like the absorbent sheets described
above. And, also like
the absorbent sheets described above, the absorbent sheets made with Fabrics
27 and 38
include bilaterally staggered domed regions that result in substantially
continuous, stepped
lines in the MD of the absorbent sheets, and substantially continuous, stepped
connecting
regions between the domed regions.
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The profiles of the domed regions in the basesheets made from Fabrics 27 and
38 were
determined using laser scanning, in the same manner that the profiles were
determined in the
absorbent sheets described above. It was found that the domed regions in the
basesheets
made with Fabric 27 had 4 to 7 indented bars, with there being an average
(mean) of 5.2
indented bars per domed region. The indented bars of domed regions extended
from about
132 to about 274 microns below the tops of adjacent areas of the domed
regions, with an
average (mean) depth of about 190 microns. Further, the domed regions extended
about 4.5
mm in the MD of the basesheets.
The domed regions in the basesheets made with Fabric 38 had 4 to 8 indented
bars, with there
being an average (mean) of 6.29 indented bars per domed region. The indented
bars of
domed regions in the basesheets made with Fabric 38 extended from about 46 to
about 159
microns below the tops of adjacent areas of the domed regions, with an average
(mean) depth
of about 88 microns. Further, the domed regions extended about 3 mm in the MD
of the
basesheets.
Because the extended MD direction domed regions in the basesheets made with
Fabrics 27
and 38 include a plurality of indented bars, it follows that the basesheets
will have similar
beneficial properties stemming from the configuration of the domed regions as
the absorbent
sheets described above. For example, the basesheets made with Fabrics 27 and
38 will be
softer to the touch compared to basesheets made with fabrics not having long
warp knuckles.
Other properties of the basesheets made with Fabrics 27 and 38 were compared
to the
properties of basesheets made with shorter knuckle fabrics. Specifically, the
caliper and
pocket depth were compared for uncalendered basesheets made with the different
fabrics.
The caliper was measured using standard techniques that are well known in the
art. It was
found that the caliper of the basesheets made with Fabric 27 varied from about
80 mils/8
sheets to about 110 mils/8 sheets, while the basesheets made with Fabric 38
varied from
about 80 mils/8 sheets to about 90 mils/8 sheets. Both of these ranges of
caliper are very
comparable, if not better than, the about 60 to about 93 mils/8 sheets caliper
that was found in
the basesheets made with shorter warp yarn knuckle fabrics under similar
process conditions.
The depths of the domed regions were measured using a topographical profile
scan of the air
side (i.e., the side of the basesheets that contacts the structuring fabric
during the
papermaking process) of the basesheets to determine the depths of the lowest
points of domed
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regions below the Yankee side surface. The depths of the domed regions in the
basesheets
made using Fabric 27 ranged from about 500 microns to about 675 microns, while
the depths
of the domed regions in the basesheets made using Fabric 38 ranged from about
400 microns
to about 475 microns. These domed regions were comparable to, if not greater
than, the
depths of the domed regions in basesheets made from the structuring fabrics
having shorter
warp yarn knuckles. This comparability of the depths of domed regions is
consistent with the
finding that the basesheets made with the long warp yarn structuring fabrics
have comparable
caliper to the basesheets made with the shorter warp yarn structuring fabrics
inasmuch as the
depth of domed regions is directly related to the caliper of an absorbent
sheet.
The characteristics of further long warp yarn knuckle fabrics according to our
invention are
labeled as Fabrics 42-44 in Figure 13. Also shown in Figure 13 is a
conventional Fabric 45
that does not include long warp yarn knuckles. Further characteristics of
Fabric 42 are given
in Figure 14, which shows the profile along one of the warp yarns of the
fabric. As can be
seen in these figures, Fabric 42 has several notable features in addition to
including long warp
yarn knuckles. One feature is that the pockets are long and deep, as reflected
in the PVI
related parameters indicated in Figure 13. As can also be seen in the pressure
imprint of
Fabric 42 shown in Figure 13, another notable feature of this fabric is that
the CD yarns are
entirely located below the plane of the knuckles in the MD yarns such that
there are no CD
knuckles at the top surface of the fabric. Because there are no CD knuckles,
there is a
gradual slope to the warp yarns in the z-direction, the details of which are
shown in the
profile scan in Figure 14. As indicated in this figure, the warp yarns have a
slope of about
200 i_tm/mm from the lowest point where the warp yarns pass under a CD yarn to
the top of
the adjacent warp knuckle. More generally speaking, the warp yarns are angled
from about
11 degrees relative to a plane that Fabric 42 moves along during the creping
operation. It is
believed that this gradual slope of the warp yarns allows the fibers in a web
being pressed to
Fabric 42 to only slightly pile up on the sloped portion of the warp yarn
before some of the
fibers slip up over the top of the adjacent knuckle. The gradual slope of the
warp yarns in
Fabric 42 thereby creates less of an abrupt stop for the fibers of the web and
less densification
of the fibers as compared to other fabrics where the warp yarns have a steeper
slope that is
contacted by the web.
Fabrics 42 and 43 both have higher PVDI-KR values, and these values in
conjunction with
the PVDI-KR values of the other structuring fabrics described herein are
generally indicative
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of the range of PVDI-KR values that can be found in embodiments of our
invention. Further,
structuring fabrics with even higher PVDI-KR values, for example, up to about
250, could
also be used.
In order to evaluate the properties of Fabric 42, a series of trials was
conducted with this
fabric and with Fabric 45 for comparison. In these trials, a papermaking
machine having the
general configuration shown in Figure 1 was used to form absorbent towel
basesheets. The
non-TAD process described generally above (and specifically set forth in the
aforementioned
'563 patent) was used, wherein the web was dewatered to the point that it had
a consistency
of about 40 to about 43 percent when transferred onto the top side of the
structuring fabric
(i.e., Fabric 42 or 45) at the creping nip. Other particular parameters of
these trails were as
shown in TABLE 4.
TABLE 4
Process Variable Location Rate
Furnish Premium ("P"): Stratified
70 % NSWK/ 30% Eucalyptus.
or
Non-premium ("NP"):
70% SSWK/ 30% SHWK
Refiner Stock Varies
WSR/CMC Static Mixer 20/3.2
(#/T total)
Debonder Addition None None
Crepe Roll Load Crepe Roll 40-60 PLI
Fabric Crepe Crepe Roll
As indicated in tables
below
Reel Crepe Reel 2%
Molding Box Molding Box
Varying between full
Vacuum and zero
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The properties of the basesheets made in these trials with Fabrics 42 and 45
are shown in
TABLES 5-9. The testing protocols used to determine the properties indicated
in TABLES
5-9 can be found in U.S. Patent Nos. 7,399,378 and 8,409,404, which are
incorporated herein
by reference in their entirety. An indication of "N/C" indicates that a
property was not
calculated for a particular trial.
24
TABLE 5
0
Trial 1 2 3 4 5 6
7 8 9 10 11 t.)
o
1-,
Fabric 45 45 45 45 45 45
45 45 45 45 45 -4
t.)
Fabric Crepe (%) 3 3 5 5 8 8 15 15
20 20 30
-4
Furnish NP NP NP NP NP NP
NP NP NP NP NP c,.)
oe
Caliper (mils/8 sheets) 63.18 62.93 68.20 67.35 77.98
77.53 84.98 88.43 92.38 90.55 99.38
Basis Weight (lb/3000 ft2) 15.17 15.42 15.33 15.38 15.31
15.34 15.59 15.28 15.85 15.50 15.47
MD Tensile (g/3 in) 1590 1554 1353 1639 1573 1498
1387 1445 1401 1145 1119
MD Stretch (%) 8.1 8.9 9.8 10.3 13.1 12.4 20.1 18.8
24.2 24.5 33.9
CD Tensile (g/3 in) 1393 1382 1294 1420 1393 1428
1401 1347 1231 1200 1272
CD Stretch (%) 4.5 4.8 4.5 4.7 4.9 4.9 6.1 7.1
6.1 6.0 7.0
P
Wet Tensile Finch
2
Cured-CD (g/3 in) 378.42 377.31 396.72 426.79 392.27 399.08
389.35 359.39 381.15 383.22 388.66 2
t.)
vi SAT Capacity (g/m2) 303.76 316.09 329.09 339.94
369.38 362.64 421.02 415.43 454.08 420.03 486.14
r.,
GM Tensile (g/3 in) 1488 1466 1323 1526 1481 1462
1394 1395 1313 1172 1193 ...'-9
,
GM Break Modulus (g/%) 254.08 227.72 198.96 220.16
186.53 189.30 130.30 116.76 108.50 97.10 78.67
,
SAT Time (s) N/C N/C N/C N/C 47.3 47.3
N/C N/C N/C N/C N/C
Tensile Dry Ratio 1.14 1.12 1.05 1.15 1.13 1.05 0.99
1.07 1.14 0.95 0.88
SAT Rate g/s 5 N/C N/C N/C N/C
0.1233 0.1073 N/C N/C N/C N/C N/C
Tensile Total Dry (g/3 in) 2983 2937 2647 3059 2967
2926 2788 2792 2632 2345 2391
Tensile Wet/Dry CD 0.27 0.27 0.31 0.30 0.28 0.28 0.28
0.27 0.31 0.32 0.31
Basis Weight Raw Wt (g) 1.147 1.166 1.159 1.163 1.158
1.160 1.179 1.156 1.198 1.172 1.170 Iv
T.E.A. CD (mm-g/mm2) 0.386 0.388 0.370 0.439 0.448
0.434 0.505 0.537 0.472 0.445 0.521 n
1-i
T.E.A. MD (mm-g/mm2) 0.693 0.759 0.733 0.911 1.043
0.982 1.461 1.400 1.700 1.431 1.993
cp
t.)
CD Break Modulus (g/%) 314.12 292.46 274.57 305.26
283.37 297.78 240.35 171.68 200.07 199.94 190.52
1-,
-4
MD Break Modulus (g/%) 205.51 177.30 144.18 158.79
122.78 120.33 70.64 79.40 58.84 47.16 32.48 o
t.)
c:
vi
o
v:,
TABLE 6
0
Trial 12 13 14 15 16 17
18 19 20 21 22 t.)
o
1-,
Fabric 45 45 42 42 42 42
42 42 42 42 42 -4
t.)
Fabric Crepe (%) 30 40 5 5 8 8 12 12
15 15 17.5
-4
Furnish NP NP NP NP NP NP
NP NP NP NP NP c,.)
oe
Caliper (mils/8 sheets) 100.03 103.35 104.73 101.30
103.33 106.95 112.40 111.78 115.83 124.73 118.75
Basis Weight (lb/3000 ft2) 15.48 15.89 15.55 15.71 15.16
15.77 15.52 14.99 15.62 15.46 15.54
MD Tensile (g/3 in) 1191 1310 1346 1404 1217 1381
1205 1118 1139 1193 1100
MD Stretch (%) 33.8 42.1 9.4 9.2 11.9 13.6 16.3
16.8 18.5 18.6 22.5
CD Tensile (g/3 in) 1216 1091 1221 1171 1164 1305
1229 1187 1208 1273 1186
CD Stretch (%) 6.4 9.7 6.7 6.5 7.6 6.7 8.2 9.0
8.9 7.3 8.4
P
Wet Tensile Finch
2
Cured-CD (g/3 in) 375.14 333.25 384.19 341.28 334.01
391.05 383.33 356.94 367.40 386.18 398.40 2
t.)
c: SAT Capacity (g/m2) 482.86 N/C 421.51 426.61
457.53 455.88 479.24 509.33 533.67 491.24 515.91
r.,
GM Tensile (g/3 in) 1203 1195 1282 1283 1191 1343
1217 1152 1173 1232 1142 ...'-9
,
GM Break Modulus (g/%) 84.14 59.92 162.90 168.66 128.36
141.14 105.49 93.56 94.07 106.55 84.05
,
SAT Time (s) N/C N/C 58.5 55.9 48.4
62.4 46.9 46.6 43.8 39.6 40.8
Tensile Dry Ratio 0.98 1.20 1.10 1.20 1.05 1.06 0.98
0.94 0.94 0.94 0.93
SAT Rate g/s 5 N/C N/C 0.1240 0.1250
0.1460 0.1330 0.1463 0.1703 0.1787 0.1653 0.1747
Tensile Total Dry (g/3 in) 2406 2401 2568 2576 2382 2686
2434 2305 2347 2466 2286
Tensile Wet/Dry CD 0.31 0.31 0.31 0.29 0.29 0.30
0.31 0.30 0.30 0.30 0.34
Basis Weight Raw Wt (g) 1.170 1.202 1.176 1.188 1.146
1.193 1.173 1.134 1.181 1.169 1.175
Iv
T.E.A. CD (mm-g/mm2) 0.493 0.614 0.486 0.458 0.504
0.520 0.561 0.586 0.600 0.527 0.555 n
1-i
T.E.A. MD (mm-g/mm2) 2.102 2.729 0.854 0.875 0.965
1.147 1.262 1.191 1.326 1.397 1.476
cp
t.)
CD Break Modulus (g/%) 200.28 115.03 186.61 185.12
160.98 196.28 149.84 131.23 142.85 172.21 141.16
=
1-,
-4
MD Break Modulus (g/%) 35.35 31.21 142.20 153.67 102.35
101.49 74.26 66.71 61.95 65.93 50.04 o
t.)
c:
vi
o
v:,
TABLE 7
0
Trial 23 24 25 26 27 28
29 30 31 32 33 t.)
o
1-,
Fabric 42 42 42 42 42 42
42 42 42 42 42 -4
t.)
Fabric Crepe (%) 17.5 20 20 25 25 3 3 5
5 8 8
-4
Furnish NP NP NP NP NP P
P P P P P c,.)
oe
Caliper (mils/8 sheets) 120.55 125.73 119.30 119.08
117.58 88.60 80.00 102.35 99.75 106.93 113.50
Basis Weight (lb/3000 ft2) 15.36 15.46 15.54 15.71 15.56
15.38 15.73 15.46 15.67 15.73 15.59
MD Tensile (g/3 in) 1156 1168 1218 1098 1164 1545
1481 1255 1336 1305 1266
MD Stretch (%) 22.7 24.9 24.5 28.8 29.6 8.6 8.3
11.5 11.5 13.5 13.4
CD Tensile (g/3 in) 1230 1137 1220 1135 1160 1353
1263 1171 1194 1202 1145
CD Stretch (%) 9.5 9.8 10.1 9.0 8.7 6.6 6.6 7.4
7.7 7.1 8.4
P
Wet Tensile Finch
2
Cured-CD (g/3 in) 389.77 355.26 412.54 353.38 358.26
394.94 400.23 365.83 380.93 404.07 342.44 2
t.)
--4 SAT Capacity (g/m2) 549.13 566.40 487.13 550.61
541.90 366.91 380.56 438.45 424.80 462.79 454.57
r.,
GM Tensile (g/3 in) 1192 1152 1219 1116 1162 1446
1368 1212 1263 1252 1204 ...'-9
,
GM Break Modulus (g/%) 79.01 75.16 77.59 69.14 71.02
189.84 187.19 134.80 135.76 127.34 114.64
,
SAT Time (s) 46.2 82.5 61.1 49.6 46.0
59.8 61.4 60.9 61.3 63.5 58.6
Tensile Dry Ratio 0.94 1.03 1.00 0.97 1.00 1.14 1.17
1.07 1.12 1.09 1.11
SAT Rate g/s 5 0.1747 0.1410 0.1297 0.1593
0.1613 0.0753 0.0917 0.1230 0.1123 0.1313 0.1263
Tensile Total Dry (g/3 in) 2386 2305 2438 2233 2324 2898
2744 2426 2530 2506 2411
Tensile Wet/Dry CD 0.32 0.31 0.34 0.31 0.31 0.29
0.32 0.31 0.32 __ 0.34 __ 0.30
Basis Weight Raw Wt (g) 1.162 1.169 1.175 1.188 1.176
1.163 1.189 1.169 1.185 1.190 1.179
Iv
T.E.A. CD (mm-g/mm2) 0.638 0.647 0.652 0.610
0.613 0.503 0.492 0.505 0.533 0.501 0.514 n
1-i
T.E.A. MD (mm-g/mm2) 1.520 1.661 1.710 1.849
1.965 0.843 0.784 0.924 0.965 1.090 1.054
cp
t.)
CD Break Modulus (g/%) 121.69 118.88 118.90 125.56
129.39 202.35 193.60 160.78 156.90 165.68 136.75 =
1-,
-4
MD Break Modulus (g/%) 51.31 47.52 50.63 38.07 38.99
178.10 181.00 113.03 117.47 97.87 96.10 o
t.)
c:
vi
o
v:,
TABLE 8
0
Trial 34 35 36 37 38
39 40 41 42 43 t.)
o
1-,
Fabric 42 42 42 42 42
42 42 42 42 42 -4
t.)
Fabric Crepe (%) 12 12 15 15 17.5 17.5 20 20
25 25
-4
Furnish P P P P P
P P P P P c,.)
oe
Caliper (mils/8 sheets) 106.90 111.85 126.78 113.55
116.38 117.43 124.28 118.38 127.15 123.45
Basis Weight (lb/3000 ft2) 15.25 15.52 15.28 15.56 15.22
15.13 15.27 15.36 15.73 15.66
MD Tensile (g/3 in) 1285 1362 1151 1099 1163 1246
1311 1268 1126 1114
MD Stretch (%) 18.0 17.8 21.4 20.1 24.2 21.7 24.1
25.6 30.0 29.5
CD Tensile (g/3 in) 1263 1291 1105 1239 1309 1156
1279 1188 1153 1215
CD Stretch (%) 8.9 8.2 9.8 8.9 9.8 10.1 10.4
10.4 11.3 10.8
P
Wet Tensile Finch
2
Cured-CD (g/3 in) 361.36 377.41 363.51 382.17 382.19
340.60 364.82 370.56 380.50 371.50 2
t.)
oe SAT Capacity (g/m2) 540.09 498.97 502.43 514.43
535.48 558.67 585.81 568.05 553.90 551.76
r.,
GM Tensile (g/3 in) 1274 1326 1128 1167 1234 1200
1295 1227 1139 1163 ...'-9
,
GM Break Modulus (g/%) 101.68 109.99 78.18 87.01 80.40
82.55 84.45 76.02 62.29 64.93
,
SAT Time (s) 37.5 42.7 55.4 47.3 50.2
51.4 45.1 44.3 66.6 53.5
Tensile Dry Ratio 1.02 1.06 1.04 0.89 0.89 1.08 1.03
1.07 0.98 0.92
SAT Rate g/s 5 0.1637 0.1557 0.1480 0.1570
0.1623 0.1553 0.1753 0.1783 0.1453 0.1483
Tensile Total Dry (g/3 in) 2548 2652 2257 2338 2472
2402 2589 2456 2279 2328
Tensile Wet/Dry CD 0.29 0.29 0.33 0.31 0.29 0.29
0.29 0.31 0.33 0.31
Basis Weight Raw Wt (g) 1.153 1.173 1.156 1.177 1.151
1.144 1.155 1.161 1.189 1.184
Iv
T.E.A. CD (mm-g/mm2) 0.627 0.625 0.566 0.600 0.676
0.617 0.695 0.659 0.691 0.703 n
1-i
T.E.A. MD (mm-g/mm2) 1.393 1.474 1.421 1.371 1.592
1.599 1.825 1.803 1.928 1.907
cp
t.)
CD Break Modulus (g/%) 145.26 158.25 111.51 137.62 134.41
116.31 128.13 116.00 101.44 113.29 =
1-,
-4
MD Break Modulus (g/%) 71.18 76.45 54.81 55.01 48.09
58.59 55.66 49.82 38.25 37.21 o
t.)
e:
vi
o
yo
TABLE 9
0
Trial 44 45
46 47 t.)
o
1-,
Fabric 42 42
42 42 -4
t.)
Fabric Crepe (%) 30 30 35 35
-4
Furnish P P
P P c,.)
oe
Caliper (mils/8 sheets) 126.38 124.25
122.83 123.23
Basis Weight (lb/3000 ft2) 15.75 15.47 15.35 14.46
MD Tensile (g/3 in) 1126 1118 1157 1097
MD Stretch (%) 35.0 35.2 33.9 34.4
CD Tensile (g/3 in) 1050 1090 1083 1097
CD Stretch (%) 11.2 10.2 10.6 10.8
P
Wet Tensile Finch 2
Cured-CD (g/3 in) 366.41 398.97
363.35 377.73 2
t.)
SAT Capacity (g/m2) 549.30 522.16
544.69 533.02
r.,
GM Tensile (g/3 in) 1088 1104 1119 1097
...'-9
,
GM Break Modulus (g/%) 54.29 56.95 59.34 56.65
,
SAT Time (s) 51.3 66.1
58.4 53.2
Tensile Dry Ratio 1.07 1.03 1.07 1.00
SAT Rate g/s 5 0.1457 0.1330
0.1543 0.1547
Tensile Total Dry (g/3 in) 2176 2208 2240 2194
Tensile Wet/Dry CD 0.35 0.37 0.34 0.34
Basis Weight Raw Wt (g) 1.191 1.170 1.161 1.093
Iv
T.E.A. CD (mm-g/mm2) 0.625 0.628
0.639 0.623 n
1-i
T.E.A. MD (mm-g/mm2) 2.094 2.062
2.049 2.074
cp
t.)
CD Break Modulus (g/%) 90.54 103.85
103.20 100.59 =
1-,
-4
MD Break Modulus (g/%) 32.55 31.23
34.12 31.90 o
t.)
c:
vi
o
v:,
CA 03024517 2018-11-15
WO 2017/213738
PCT/US2017/026509
The results of the trials shown in TABLES 5-9 demonstrate that Fabric 42 can
be used to
produce basesheets having an outstanding combination of properties,
particularly caliper and
absorbency. Without being bound by theory, we believe that these results stem,
in part, from
the configuration of knuckles and pockets in Fabric 42. Specifically, the
configuration of
Fabric 42 provides for a highly efficient creping operation due to the aspect
ratio of the
pockets (i.e., the length of the pockets in the MD versus the width of the
pockets in the CD),
the pockets being deep, and the pockets being formed in long, near continuous
lines in the
MD. These properties of the pockets allow for great fiber "mobility," which is
a condition
where the wet compressed web is subjected to mechanical forces that create
localized basis
weight movement. Moreover, during the creping process, the cellulose fibers in
the web are
subjected to various localized forces (e.g., pushed, pulled, bent,
delaminated), and
subsequently become more separated from each other. In other words, the fibers
become de-
bonded and result in a lower modulus for the product. The web therefore has
better vacuum
"moldability," which leads to greater caliper and a more open structure that
provides for
greater absorption.
The fiber mobility provided for with the pocket configuration of Fabric 42 can
be seen in the
results shown in Figures 15 and 16. These figures compare the caliper, SAT
capacity, and
void volume at the various crepe levels used in the trials. Figures 15 and 16
show that, even
in the trials with Fabric 42 where no vacuum molding was used, the caliper and
SAT capacity
increased with the increasing fabric crepe level. As there was no vacuum
molding, it follows
that these increases in caliper and SAT capacity are directly related to fiber
mobility in Fabric
42. Figures 15 and 16 also demonstrate that a high amount of caliper and SAT
capacity are
achieved using Fabric 42¨in the trials where vacuum molding is used, at each
creping level
the caliper and SAT capacity of the basesheets made with Fabric 42 were much
greater than
the caliper and SAT capacity of the basesheets made with Fabric 45.
The fiber moldability provided by Fabric 42 can also be seen in the results
shown in Figure
15 and 16. Specifically, the differences between the caliper and SAT capacity
in the trials
with no vacuum molding and the trials with vacuum molding demonstrates that
the fibers in
the web are highly moldable on Fabric 42. As will be discussed below, vacuum
molding
draws out the fibers in the regions of the web formed in the pockets of Fiber
42. The large
fiber moldability means that the fibers are highly drawn out in this molding
operation, which
leads to the increased caliper and SAT capacity in the resulting product.
CA 03024517 2018-11-15
WO 2017/213738
PCT/US2017/026509
Figure 19 also evidences that greater fiber mobility is achieved with Fabric
42 by comparing
the void volume of the basesheets from the trials at the fabric crepe levels.
The absorbency
of a sheet is directly related to void volume, which is essentially a measure
of the space
between the cellulose fibers. Void volume is measured by the procedure set
forth in the
aforementioned U.S. Patent No. 7,399,378. As shown in Figure 19, the void
volume
increased with the increasing fabric crepe in the trials using Fabric 42 where
no vacuum
molding was used. This indicates that the cellulose fibers were more separated
from each
other (i.e., de-bonded, with a lower resulting modulus) at each fabric crepe
level in order to
produce the additional void volume. Figure 19 further demonstrates that, when
vacuum
molding is used, Fabric 42 produces basesheets with more void volume than the
conventional
Fabric 45 at each fabric crepe level.
The fiber mobility when using Fabric 42 can also be seen in Figures 20A, 20B,
21A, and
21B, which are soft x-ray images of basesheets made using Fabric 42. As will
be appreciated
by those skilled in the art, soft x-ray imaging is a high-resolution technique
that can be used
for gauging mass uniformity in paper. The basesheets in Figures 20A and 20B
where made
with an 8 percent fabric crepe, whereas the basesheets in Figures 21A and 21B
were made
with a 25 percent fabric crepe. Figures 20A and 21A show fiber movement at a
more
"macro" level, with the images showing an area of 26.5 mm by 21.2 mm. Wave-
like patterns
of less mass (corresponding to the lighter regions in the images) can be seen
with the higher
fabric crepe (Figure 21A), but regions of less mass are not readily seen with
the lower fabric
crepe (Figure 20A). Figures 20B and 21B show the fiber movement at a more
"micro" level,
with the images showing an area of 13.2 mm by 10.6 mm. The cellulose fibers
can clearly be
seen as more distanced from each other and pulled apart with the higher fabric
crepe (Figure
21B) than with the lower fiber crepe (Figure 20B). Collectively, the soft x-
ray images further
confirm that Fabric 42 provides for greater fiber mobility with the higher
localized mass
movement being seen at the higher fabric crepe level than at the lower fabric
crepe level.
Figures 17 and 18, and also Figure 19, show the results of the trials in terms
of the furnish.
Specifically, these figures show that Fabric 42 can produce comparable amounts
of caliper,
SAT capacity, and void volume when using the non-premium furnish as well as
with the
premium furnish. This is a very beneficial result as it demonstrates that the
Fabric 42 can
achieve outstanding results with a lower cost, non-premium furnish.
31
CA 03024517 2018-11-15
WO 2017/213738
PCT/US2017/026509
Because Fabric 42 has extra-long warp yarn knuckles, as with the other extra-
long warp yarn
knuckle fabrics described above, the products made with Fabric 42 may have
multiple
indented bars extending in a CD direction. The indented bars are again the
result of folds
being created in the areas of the web that are moved into the pockets of the
structuring fabric.
In the case of Fabric 42, it is believed that the aspect ratio of the length
of the knuckles and
the length across the pocket even further enhances the formation of the
folds/indented bars.
This is because the web is semi-restrained on the long warp knuckles while
being more
mobile within the pockets of Fabric 42. The result is that the web can buckle
or fold at
multiple places along each pocket, which in turn leads to the CD indented bars
seen in the
products.
The indented bars formed in absorbent sheets made from Fabric 42 can be seen
in Figures
22A-22E. These figures are images of the air-side of products made with Fabric
42 at
different fabric creping levels but with no vacuum molding. The MD is in the
vertical
direction in all of these figures. Notably, instead of having sharply defined
dome regions like
the products described above, the products in Figures 22A-22E are
characterized by having
parallel and near-continuous lines of projected regions substantially
extending in the MD,
with each of the extended projected regions including a plurality of indented
bars extending
across the projected regions in a substantially CD of the absorbent sheet.
These projected
regions correspond to lines of pockets extending in the MD of Fabric 42.
Between the
projected regions are connecting regions that also extend substantially in the
MD. The
connecting regions correspond to the long warp yarn knuckles of Fabric 42.
The product in Figure 22A was made with a fabric crepe of 25%. In this
product, the
indented bars are very distinct. It is believed that this pattern of indented
bars is the result of
the fiber network on Fabric 42 experiencing a wide range of forces during the
creping
process, including in-plane compression, tension, bending, and buckling. All
of these forces
will contribute to the fiber mobility and fiber moldability, as discussed
above. And, as a
result of the near continuous nature of the projected regions extending in the
MD, the
enhanced fiber mobility and fiber moldability can take place in a near
continuous manner
along the MD.
.. Figures 22B-22E show the configuration of products with less fabric creping
as compared to
the product shown in Figure 22A. In Figure 22B, the fabric crepe level used to
form the
32
CA 03024517 2018-11-15
WO 2017/213738
PCT/US2017/026509
depicted product was 15%, in Figure 22C the fabric crepe level was 10%, in
Figure 22D the
fabric crepe level was 8%, and in Figure 22E the fabric crepe level was 3%. As
would be
expected, the amplitude of the folds/indented bars can be seen to decrease
with the decreasing
fabric crepe level. However, it is notable that the frequency of the indented
bars remains
about the same through the fabric crepe levels. This indicates that the web is
buckling/folding in the same locations relative to the knuckles and pockets in
Fabric 42
regardless of fabric crepe level being used. Thus, beneficial properties
stemming from the
formation of folds/indented bars can be found even at lower fabric crepe
levels.
In sum, Figures 22A-22E show that the high pocket aspect ratio of Fabric 42
has the ability to
uniformly exert decompacting energy to the web such that fiber mobility and
fiber
moldability are promoted over a wide fabric creping range. And, this fiber
mobility and fiber
moldability is a very significant factor in the outstanding properties, such
as caliper and SAT
capacity, found in the absorbent sheets made with Fabric 42.
Figures 23A-24B are scanning electron microscopy images of the air sides of a
product made
with Fabric 42 (Figures 23A and 24A) and a comparison product made with Fabric
45
(Figures 23B and 24B). In these cases, the products were made with 30% fabric
crepe and
maximum vacuum molding. The center regions of the images in Figures 23A and
23B show
areas made in the pockets of the respective fabrics, with areas surrounding
the center regions
corresponding to regions formed on knuckles of the respective fabrics. The
cross sections
shown in Figures 24A and 24B extend substantially along the MD, with an
extended
projected region of the Fabric 42 product being seen in Figure 24A and with
multiple domes
(as formed in multiple pockets) being seen in the Fabric 45 product shown in
Figure 24B. It
can very clearly be seen that the fibers in the product made with Fabric 42
are much less
densely packed than the cellulose fibers in the product made with Fabric 45.
That is, the
center dome regions in the Fabric 45 product are highly dense¨as dense, if not
more dense,
than the connecting region surrounding the pocket region in the Fabric 42
product.
Moreover, Figures 24A and 24B show the fibers to be much looser, i.e., less
dense, in the
Fabric 42 product than in the Fabric 45 product, with distinct fibers
springing out from the
Fabric 42 product structure in Figure 24A. Figures 23A-24B thereby further
confirm that that
Fabric 42 provides for a large amount of fiber mobility and fiber moldability
creping process,
which in turn results in regions of significantly reduced density in the
absorbent sheet
products made with the fabric. The reduced density regions provide for greater
absorbency in
33
CA 03024517 2018-11-15
WO 2017/213738
PCT/US2017/026509
the products. Further, the reduced density regions provide for more caliper as
the sheet
becomes more "puffed out" in the reduced density regions. Still further, the
puffy, less dense
regions will result in the product feeling softer to the touch.
Further trials were conducted using Fabric 42 to evaluate properties of
converted towel
products according to embodiments of our invention. For these trials, the same
conditions
were used as in the trials described in conjunction with TABLES 4 and 5. The
basesheets
were then converted to two-ply paper towel. TABLE 10 shows the converting
specifications
for these trials. Properties of products made in these trials are shown in
TABLES 11-13.
TABLE 10
Conversion Process Gluing
Number of Plies 2
Roll Diameter Varying
Sheet Count 60
Sheet Length 10.4
Sheet Width 11 in.
Roll Compression 6 ¨ 12%
Emboss Process Following process of U.S. Patent
No.
6,827,819 with the embossing pattern
shown in U.S. Patent Design No. D504236
(which is incorporated
by reference in its entirety)
Emboss Pattern Constant/Non-Varying
34
0
TABLE 11 tµ.)
o
,-,
-4
n.)
Trial 1 2 3 4 5 6
7 8 9 10
-4
Fabric 42 42 42 42 42 42
42 42 42 42 c,.)
oe
Fabric Crepe (%) 3 5 8 12 15
17.5 20 25 30 35
Furnish P P P P P P
P P P P
Basis Weight (lbs/ream) 31.57 31.39 31.27 31.12 31.21
30.94 31.34 31.69 31.50 29.99
Caliper (mils/8 sheets) 152.9 183.1 185.9 204.1 215.2
218.7 225.2 236.0 229.9 223.3
MD Tensile (g/3 in) 3,296 2,716 2,786 2,651 2,454 2,662
2,624 2,405 2,553 2,363
CD Tensile (g/3 in) 2,656 2,479 2,503 2,526 2,420 2,617
2,668 2,478 2,279 2182
P
GM Tensile (g/3 in) 2,958 2,595 2,641 2,588 2,437 2,639
2,646 2,441 2,412 2271 .
Tensile Ratio 1.24 1.10 1.11 1.05 1.01
1.02 0.98 0.97 1.12 1.08
un MD Stretch (%) 8.7 11.0 13.5 17.3 20.3
22.6 25.2 28.5 32.3 32.2 ...]
r.,
CD Stretch (%) 6.1 7.0 7.7 8.3 9.0
9.0 9.4 10.1 10.6 10.7 ,
.3
,
,
CD Wet Tensile - Finch (g/3 in) 797 724 738 747 746
788 803 729 728 707 ,
,
,
CD Wet/Dry - Finch (%) 30.0 29.2 29.5 29.6 30.8 30.1
30.1 29.4 31.9 32.4
Perf Tensile (g/3") 608 534 577 572 562
601 560 495 616 514
SAT Capacity (g/m2) 344 404 385 416 450 465 479
530 527 520
SAT Capacity (g/g) 6.7 7.9 7.6 8.2 8.9 9.2 9.4
10.3 10.3 10.6
SAT Rate (g/sec 5) 0.09 0.15 0.10 0.12 0.14
0.15 0.15 0.18 0.17 0.19
GM Break Modulus (g/%) 407.2 295.3 257.7 216.5
180.4 183.4 172.7 144.8 130.0 122.8 Iv
n
Roll Diameter (in) 4.57 4.93 5.01 5.03 5.07
5.08 5.15 5.35 5.12 5.14 1-3
Roll Compression (%) 12.1 11.56 12.38 10.06 7.89
7.81 6.93 8.78 6.90 7.52 cp
n.)
o
Sensory Softness N/C 10.1 9.7 N/C N/C
N/C 9.0 9.2 N/C N/C 1--,
-4
o
n.)
c:
un
o
v:,
0
TABLE 12 tµ.)
o
,-,
-4
n.)
Trial 11 12 14 15 16 17
18 19 20 21
-4
Fabric 42 42 42 42 42 42
42 42 42 42 c,.)
oe
Fabric Crepe (%) 35 5 8 12 15
17.5 20 25 20 25
Furnish P NP NP NP NP NP
NP NP NP NP
Basis Weight (lbs/ream) 29.99 31.41 31.67 31.09 31.61 31.34
31.60 31.85 31.43 31.26
Caliper (mils/8 sheets) 223.3 175.6 183.0 197.8 213.4 212.3
220.6 220.3 200.3 208.2
MD Tensile (g/3 in) 2,363 2,878 2,885 2,481 2,447
2,385 2,397 2374 2,684 2424
CD Tensile (g/3 in) 2182 2,495 2,621 2,523 2,563
2,615 2,523 2341 2,545 2591
GM Tensile (g/3 in) 2271 2,680 2,750 2,502 2,505
2,497 2,460 2357 2,613 2506 P
Tensile Ratio 1.08 1.15 1.10 0.98 0.95
0.91 0.95 1.01 1.05 0.94 .
r.,
MD Stretch (%) 32.2 10.1 12.9 16.9 19.0
20.5 23.0 28.5 23.8 27.4 ,
...]
c:
r.,
CD Stretch (%) 10.7 7.2 7.6 8.2 8.1
8.6 8.8 9.6 8.5 8.4 .
,
.3
,
CD Wet Tensile - Finch (g/3 in) 707 767 828 825 752
758 752 770 865 738 ,
,
,
,
CD Wet/Dry - Finch (%) 32.4 30.7 31.6 32.7 29.3 29.0 29.8
32.9 34.0 28.5
Perf Tensile (g/3 in) 514 644 668 575 586 496 580
602 614 530
SAT Capacity (g/m2) 520 362 402 430 497 490 520
514 473 499
SAT Capacity (g/g) 10.6 7.1 7.8 8.5 9.7 9.6 10.1
9.9 9.2 9.8
SAT Rate (g/sec 5) 0.19 0.11 0.14 0.14 0.22 0.23
0.22 0.20 0.19 0.24
GM Break Modulus (g/%) 122.8 313.3 278.5 211.4
201.2 188.2 171.6 144.0 182.3 164.6
Iv
Roll Diameter (in) 5.14 4.79 4.84 4.89 5.13
5.05 5.31 5.10 5.03 5.01 n
,-i
Roll Compression (%) 7.52 8.70 9.02 7.08 9.48
7.52 11.74 6.86 10.14 7.71
cp
Sensory Softness N/C 9.4 N/C N/C 9.2
N/C 9.2 9.1 N/C 8.8 n.)
o
1--,
-4
o
n.)
c:
un
o
v:,
0
TABLE 13
t..)
o
1-,
--4
t..)
Trial 22 23 24 25
265 27 28
--4
Fabric 42 45 45 45
45 45 45 c,.)
oe
Fabric Crepe (%) 25 3 5 8
15 20 30
Furnish NP NP NP NP
NP NP NP
Basis Weight (lbs/ream) 26.22 31.20 31.53
30.83 31.11 31.24 30.98
Caliper (mils/8 sheets) 120.3 130.5 137.3
159.3 164.1 172.5 182.3
MD Tensile (g/3 in) 2687 2,939 2,742
2,787 2,647 2,649 2,629
CD Tensile (g/3 in) 2518 2,569 2,510
2,664 2,726 2,647 2,594
P
GM Tensile (g/3 in) 2601 2,748 2,623
2,724 2,686 2,648 2,611 .
Tensile Ratio 1.07 1.14 1.09
1.05 0.97 1.00 1.01 .."
u,
--4 MD Stretch (%) 30.0 8.4 9.3
18.7 18.1 21.7 31.1 ,
r.,
CD Stretch (%) 7.9 5.1 5.0 6.3
6.4 7.0 7.7 ,
T
rl
CD Wet Tensile - Finch (g/3 in) 793 732 767 764
756 766 789 ,
CD Wet/Dry - Finch (%) 31.5 28.5 30.5
28.7 27.7 28.9 30.4
Perf Tensile (g/3 in) 613 621 528 593
637 591 570
SAT Capacity (g/m2) 215 298 314 384
386 406 404
SAT Capacity (g/g) 5.0 5.9 6.1 7.7
7.6 8.0 8.0
SAT Rate (g/sec 5) 0.04 0.10 0.10
0.14 0.14 0.15 0.14
GM Break Modulus (g/%) 168.2 422.4 385.5
276.5 249.2 213.6 166.6 1-d
n
Roll Diameter (in) 5.24 4.35 4.36
4.44 4.54 4.61 4.55
(7)
Roll Compression (%) 6.16 14.5 13.9
10.0 9.1 8.4 5.2 t.)
o
Sensory Softness Softness N/C N/C 9.3 N/C
N/C 8.7 8.4 --4
o
t..)
o
vi
o
o
CA 03024517 2018-11-15
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PCT/US2017/026509
Note that Trial 22 only formed a one-ply product, but was otherwise converted
in the same
manner as the other trials.
The results shown in TABLES 11-13 demonstrate the excellent properties that
can be
achieved using a long warp warn knuckle fabric according to our invention. For
example, the
final products made with Fabric 42 had higher caliper and higher SAT capacity
than the
comparison products made with Fabric 45. Further, the results in TABLES 11-13
demonstrate that very comparable products can be made with Fabric 42
regardless of whether
a premium or a non-premium furnish is used.
Based on properties of the products made in the trials described herein, it is
clear that the long
warp yarn knuckle structuring fabrics described herein can be used in methods
that provide
products having outstanding combinations of properties. For example, the long
warp yarn
knuckle structuring fabrics described herein can be used in conjunction with
the non-TAD
process described generally above and specifically set forth in the
aforementioned '563
patent, (wherein the papermaking furnish is compactively dewatered before
creping) to form
an absorbent sheet that has SAT capacities of at least about 9.5 g/g and at
least about 500
g/m2. Further, this absorbent sheet can be formed in the method while using a
creping ratio
of less than about 25%. Even further, the method and long warp yarn knuckle
structuring
fabrics can be used to produce an absorbent sheet that has SAT capacities of
at least about at
least about 10.0 g/g and at least about 500 g/m2, has a basis weight of less
than about 30
.. lbs/ream, and a caliper 220 mils/8 sheets. We believe that this type of
method has never
created such an absorbent sheet before.
Further absorbent towel basesheets were made in trials with Fabrics 42 and 45.
These trials
were conducted on a papermaking machine having a configuration as shown in
Figure 1,
using the non-TAD process described generally above (and specifically set
forth in the
aforementioned '563 patent), and the parameters for these trials were the same
as those
shown and described in TABLE 4 above. The results of these trials are shown in
TABLES
14-16 below.
38
TABLE 14
0
Trial 1 2 3 4 5 6 7
8 9 10 t.)
o
Fabric 42 42 42 42 42 42 42
42 42 42
-4
Fabric Crepe (%) 3 5 8 12 15 17.5
20 25 30 35 t.)
1-,
Furnish P P P P P P P
P P P c,.)
-4
Basis Weight (lbs/ream) 15.56 15.57 15.66 15.38 15.42
15.17 15.31 15.69 15.61 14.90 c'e
Caliper (mils/8 sheets) 84.3 101.1 110.2 109.4 120.2 116.9
121.3 125.3 125.3 123.0
Bulk (cc/g) 10.6 12.7 13.7 13.9 15.2 15.0
15.5 15.6 15.6 16.1
MD Tensile (g/3 in) 1513 1295 1285 1323 1125 1205
1290 1120 1122 1127
CD Tensile (g/3 in) 1308 1183 1173 1277 1172 1233
1233 1184 1070 1090
GM Tensile (g/3 in) 1407 1238 1228 1300 1147 1217
1261 1151 1096 1108
Tensile Ratio 1.16 1.10 1.10 1.04 0.96 0.98
1.05 0.95 1.05 1.03
MD Stretch (%) 8.4 11.5 13.5 17.9 20.7 23.0
24.9 29.8 35.1 34.1
P
CD Stretch (%) 6.6 7.6 7.8 8.6 9.3 9.9
10.4 11.0 10.7 10.7
2
CD Wet Tensile-Finch (g/3 in) 398 373 373 369 373
361 368 376 383 371 2
CD Wet/Dry-Finch (%) 30.4 31.6 31.8 28.9 31.8 29.3
29.8 31.8 35.8 34.0
SAT Capacity (g/m2) 373.7 431.6 458.7 519.5 508.4 547.1
576.9 552.8 535.7 538.9
SAT Capacity (g/g) 7.38 8.52 9.00 10.38 10.13 11.08
11.57 10.82 10.54 11.11
SAT Rate (g/sec 5) 0.08 0.12 0.13 0.16 0.15 0.16
0.18 0.15 0.14 0.15
,
GM Break Modulus (g/%) 188.5 135.3 121.0 105.8 82.6 81.5
80.2 63.6 55.6 58.0
Iv
n
1-i
cp
t.)
o
,-,
-4
o
t.)
o
u,
o
o
TABLE 15
_______________________________________________________________________________
__________________________________________ 0
Trial 11 12 13 14 15
16 17 18 19
6'
Fabric 42 42 42 42 42
42 42 42 42 1-
--4
Fabric Crepe (%) 5 8 12 15
17.5 20 25 20 25 t..)
Furnish NP NP NP NP NP NP
NP NP NP NP c,.)
--4
Basis Weight (lbs/ream) 15.63 15.47 15.25 15.54
15.45 15.50 15.63 15.51 15.31 c'e
Caliper (mils/8 sheets) 103.0 105.1 112.1 120.3
119.7 122.5 118.3 113.8 116.2
Bulk (cc/g) 12.9 13.3 14.3 15.1
15.1 15.4 14.8 14.3 14.8
MD Tensile (g/3 in) 1375 1299 1161 1166
1128 1193 1131 1213 1106
CD Tensile (g/3 in) 1196 1235 1208 1241
1208 1178 1148 1282 1236
GM Tensile (g/3 in) 1282 1267 1184 1203
1167 1186 1139 1247 1169
Tensile Ratio 1.15 1.05 0.96 0.94
0.93 1.01 0.99 0.95 0.90
MD Stretch (%) 9.3 12.7 16.5 18.6
22.6 24.7 29.2 24.4 29.0 p
CD Stretch (%) 6.6 7.1 8.6 8.1
8.9 10.0 8.8 8.6 8.8 2
CD Wet Tensile - Finch (g/3 in) 363 363 370 377
394 384 356 396 382 2
.6. CD Wet/Dry - Finch (%) 30.3 29.4 30.6 30.4
32.6 32.6 31.0 30.9 30.9
o
SAT Capacity (g/m2) 424.1 456.7 490.7 512.5
532.5 526.8 546.3 460.7 515.1
,2
SAT Capacity (g/g) 8.34 9.07 9.88 10.13
10.59 10.44 10.74 9.12 10.34
1!
SAT Rate (g/sec 5) 0.12 0.14 0.16 0.17
0.17 0.14 0.16 0.13 0.15 ,
GM Break Modulus (g/%) 165.8 134.8 99.5 100.3
81.5 76.4 70.1 86.8 73.9
1-d
n
1-i
cp
t..)
o
,-,
-4
o
t..)
o
u,
o
o
TABLE 16
0
Trial 20 21 22 23
24 25 t..)
o
Fabric 45 45 45 45
45 45 1-
--.1
Fabric Crepe (%) 3 5 8 15
20 30 t..)
Furnish NP NP NP NP NP
NP NP c,.)
--.1
Basis Weight (lbs/ream) 15.30 15.36 15.32
15.44 15.67 15.47 c'e
Caliper (mils/8 sheets) 63.1 67.8 77.8
86.7 91.5 99.7
Bulk (cc/g) 8.0 8.6 9.9
11.0 11.4 12.6
MD Tensile (g/3 in) 1572 1496 1535
1416 1273 1155
CD Tensile (g/3 in) 1388 1357 1411
1374 1216 1244
GM Tensile (g/3 in) 1477 1424 1472
1395 1243 1198
Tensile Ratio 1.13 1.10 1.09
1.03 1.05 1.03
MD Stretch (%) 8.5 10.0 12.7
19.4 24.3 33.9 p
CD Stretch (%) 4.6 4.6 4.9
6.6 6.1 6.7
2
CD Wet Tensile - Finch (g/3 in) 378 412 396
374 382 382 2
.6. CD Wet/Dry - Finch (%) 27.2 31.6 28.0
27.2 31.4 30.7
1-
SAT Capacity (g/m2) 310 334 366
418 437 485 0"
SAT Capacity (g/g) 6.2 6.7 7.3
8.3 8.6 9.6
rl
SAT Rate (g/sec 5) 0.09 0.11 0.12
0.14 0.16 0.18 ,
GM Break Modulus (g/%) 240.9 209.6 187.9
123.5 102.8 81.4
1-d
n
1-i
cp
t..)
o
,-,
-4
o
t..)
o
u,
o
o
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As with the previously-described trials, the absorbent sheets made using
Fabric 42 in the
trials shown in TABLES 14-16 have an outstanding combination of properties, in
particular,
outstanding caliper and absorbency.
Figures 25A and 25B indicate characteristics of further structuring fabrics
according to
embodiments of our invention. Like the fabrics discussed above, the Fabrics 46-
52 shown in
Figures 25A and 25B have long warp yarn knuckles, which range from about 2.4
mm to
about 5.7 mm. Also like fabrics discussed above, Fabric 46-52 have high PVDI-
KR values,
ranging from about 41 to about 123.
The Fabrics 46-52 also demonstrate another aspect of our invention related to
positioning of
the knuckles on the web-contacting surface of structuring fabrics. As can be
seen from the
pressure imprint pictures, the knuckles in Fabrics 46-52 are positioned
relative to each other
such that straight lines can be drawn through the centers of a plurality of
the knuckles. One
such line Li is shown in Figure 26, which is a detailed view of the pressure
imprint of Fabric
50. The angle a of line Li relative to a line MDL that runs along the MD of
the fabric is
about 15 . In other structuring fabrics according to embodiments of our
invention, warp yarn
knuckle lines can be between about 100 to about 30 relative to an MD line,
and in more
specific embodiments, the warp yarn knuckle lines can be between about 10 to
about 20
relative to an MD line. The angles of the warp yarn knuckle lines for Fabrics
46-52 are given
in Figures 25A and 25B. It should also be noted that some of the other fabrics
described
herein include similar angled lines of warp yarn knuckles, including, for
example, Fabric 42
shown in Figure 13.
We have found that paper products made with structuring fabrics having angled
warp yarn
knuckle lines, such as those shown in Fabrics 42 and 46-52, have exceptional
properties.
Without being bound by theory, we believe that these exceptional properties
stem from a
large amount of fiber mobility that is provided for by structuring fabrics
having angled warp
yarn knuckle lines.
This fiber mobility of a structuring fabric that has angled warp yarn knuckle
lines is
demonstrated in Figure 27A, and this fiber mobility can be compared to other
structuring
fabric configurations as shown in Figures 27B and 27C. The fibers are moved to
the fold
formations 4002 and 5002 shown in these figures, for example, during a creping
operation,
such as when the web 116 is transferred from the backing roll 108 to the
structuring fabric
42
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112 in the creping nip 120, as shown in Figure 1 and as described above.
Figure 27B
illustrates the case of an MD knuckle 4000 in a structuring fabric. The
cellulose fibers of the
web are stacked in dense folds 4002 against an edge 4004 of the knuckle 4000
during the
creping process, thereby creating a localized densification zone 4006 adjacent
to the knuckle
4000. Such localized densification of fibers would also occur at other MD
knuckles in the
structuring fabric. Figure 27C shows how a CD knuckle 5000 of a structuring
fabric also has
a localized densification zone as a result of web folds 5002 piling up against
an edge 5004 of
the knuckle 5000.
In contrast, the knuckles 6000 in the angled warp yarn lines shown in Figure
27A result in a
much different fold formations than the fold formations illustrated in Figures
27B and 27C.
With the angled warp yarn knuckle lines, a strain field arises though the
combination of the
movement of the knuckles 6000 and the adhesion of the web 116 to the backing
roll 108.
The strain field is localized to the pocket regions between the knuckles 6000.
The strain field
arises because of the creping ratio speed differential in the web transfer
from the transfer
surface to the structuring fabric: in the creping nip, portions of the web are
pulled in a
downstream direction by the faster moving transfer surface, while other
portions of the web
are effectively held up by the slower moving knuckles 6000. During the creping
operation,
the web is, for example, 40% to 45% solids, which means that the web will
behave in a
substantially viscous manner. Thus, fibers of the web in the strain field can
be permanently
repositioned relative to each other¨after exiting the creping operation, the
fibers do not
recover to their relative positioning before they entered the strain field.
This fiber
mobilization in the strain field increases the fiber-fiber distance, and
thereby weakens the
bonds between the fibers so that the web can be molded more easily. The result
is that the
fibers are distributed in curved folds in the pockets between the knuckles
6000. The curved
folds are an indication that fiber mobilizing work has occurred in the
pockets. And, as
indicated by the results of the trials described above, there are significant
improvements in
absorbency and softness when fiber mobilization leading to the curved folds is
achieved, as
evidence, for example, by the SAT and void volumes of the absorbent sheets
made by Fabric
42.
.. The curved folds are shaped such that apexes 6003 of the curved folds are
positioned
downstream in the MD, and ends of the curved folds are offset in the MD, with
ends 6007 of
the curved folds being positioned upstream in the MD relative to the other
ends 6009 of the
43
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curved folds. In comparison, the curved folds shown in Figure 27A are
significantly less
dense than the piles of fibers formed at the edges of MD and CD knuckles in
structuring
fabrics not having angled warp yarn lines shown in Figures 27B and 27C. And,
we believe
that absorbent sheets have greatly improved softness and absorbency because of
the reduced
densification of the curved folds, which in turn relates to the fiber
mobilization discussed
above.
The shapes of the curved folds are also related to the distances D1 between
the knuckles
6000. As will be appreciated by those skilled in the art, if the knuckles 6000
are too close,
there will not be enough room in the pocket between the knuckles 6000 for the
fibers to move
into the less dense, curved folds. On the other hand, if the knuckles are too
far apart, many of
the fibers will not be subjected to the strain field action of the faster
moving transfer surface
and the slower moving knuckles, and thus, fewer, less pronounced, curved folds
may be
formed in the web and the resultant absorbent sheet. With these considerations
in mind, in
embodiments of our invention the distances D1 between the centers of two
adjacent knuckles
6000 in different warp yarn knuckle lines can be about 1.5 mm to about 4.0 mm.
In a specific
embodiment, the distances D1 are about 2.0 mm. With the 2.0 mm distance
between the
knuckles 6000, there is about 1.5 mm of room in the pocket region between the
two adjacent
knuckles 6000.
Figures 28A-28E are photographs of absorbent basesheets made with a
structuring fabric
having angled warp yarn knuckle lines, with a papermaking machine having the
general
configuration shown in Figure 1, using the non-TAD process described generally
above (and
specifically set forth in the aforementioned '563 patent), and with the
parameters shown in
TABLE 4 above. Different creping ratios (i.e., fabric crepe %) and different
molding box
vacuums were used for each of the basesheets shown in Figures 28A-28E.
Specifically, the
basesheet in Figure 28A was made with a 25% crepe ratio and a molding box
vacuum of 2 in.
Hg, the basesheet in Figure 28B was made with a 25% crepe ratio and a molding
box vacuum
of 8 in. Hg, the basesheet in Figure 28C was made with a 30% crepe ratio and a
molding box
vacuum of 10 in. Hg, and the basesheet in Figure 28D was made with a 25% crepe
ratio and a
molding box vacuum of 8 in. Hg. The basesheet shown in Figure 28E was made
with a 20%
crepe ratio, but no molding box vacuum. Note, as there is no vacuum molding
used in the
production of the basesheet shown in Figure 28E, the basesheet is also
indicative of the
structure of web following the creping operation in the papermaking process.
That is, the
44
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web in the papermaking process would have the same general curved fold
formations as the
basesheet product shown in Figure 28E. It should also be noted that different
creping ratios
may be used in conjunction with structuring fabrics having angled warp yarn
knuckle lines in
other embodiments of our invention. In some embodiments, the creping ratio
used with an
angled warp yarn knuckle line fabric is between about 3% and about 100%, in
more specific
embodiments, the creping ratio is between about 3% to about 50%, in even more
specific
embodiment, the creping ratio is between about 5% and 30%.
Curved folds can clearly be seen in the projected regions of the basesheets
shown in Figures
28A-28E. In these figures, the MD of the sheets is in the vertical (i.e., up
and down)
direction, with the upstream side of the sheets being at the top of the
pictures and the
downstream side of the sheets being at the bottom of the figures. In Figure
28A some of the
curved folds have been marked with dotted lines. As a result of the angled
warp yarn knuckle
lines, the ends of the curved shapes are unsymmetrical: one end of the curved
folds is
positioned more downstream than the other end of the curved folds. The curved
folds extend
between these two ends to an apex that is at a downstream most part of the
curved folds.
And, the ends of the curved folds are positioned adjacent to connecting
regions, which
correspond to the knuckles of the fabric.
Curved folds can also be seen in the absorbent sheets shown in Figures 22A and
22E. As
previously noted, the absorbent sheets in these figures were formed using
Fabric 42, which
includes angled lines of warp yarn knuckles. Further, the curved folds can be
seen in the soft
x-ray images shown in Figures 21A and 21B.
Figures 28A-28E also show that multiple curved folds are formed in each of the
projected
regions. The multiple curved folds are a result of the extended length in the
MD direction of
the pockets in which the domed regions are formed, and, thus, the curved folds
are also
related to the length of the warp yarn knuckles. As the web is transferred to
the structuring
fabric in the process of making absorbent sheets using a creping operation (as
discussed
above), multiple folds are created in the structure of the web within the
pockets. Thus, in the
same manner that multiple intended bars are formed in each of the projected
regions of the
absorbent sheets in the embodiments discussed above, multiple indented bars
are formed
.. between the multiple curved folds in the projected regions of the absorbent
sheets shown in
CA 03024517 2018-11-15
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Figures 28A-28E. Such indented bars can be seen between the curved folds in
the absorbent
sheets shown in Figures 28A-28E.
The connecting regions connect the projected regions having the curved folds
can also be
seen in the photographs of the basesheets shown in Figures 28A-28E. These
connecting
regions largely correspond to the parts of the sheet that were formed on the
knuckles of
fabrics used to make these sheets, as well as parts of the sheet that were
formed in regions
adjacent to the knuckles and pockets. An aspect of the connecting regions of
the basesheet
according to our invention is highlighted in Figure 28A, wherein regions
adjacent to upstream
ends of the projected regions are circled. It can be seen that the sheet has
folded in these
circled regions. These folds are formed because of a z-direction slope in the
warp yarns, and
lack of CD knuckles, as discussed above. In particular, the web can slide into
these parts of
the connecting regions in the papermaking process, thereby creating the folds.
The folds in
the connecting regions act to further reduce the density of the fibers,
thereby further
improving properties of the absorbent sheets.
Based on photographs such as those shown in Figures 28A-28E, a radius of
curvature for the
curve folds can be calculated. Specifically, circles can be drawn such that
arcs of the circles
align with the curved folds. As is evident from the photographs shown in
Figures 28A-28E,
the leading (downstream) edges of the curved folds are most prominent, and,
thus, it is easiest
to draw the circles such that the arcs align with the leading edges. Figure 29
is the same
photograph as Figure 28A, additionally showing circles with arcs aligned with
the leading
edges of some of the curved folds. From such circles, and using the scale of
the photograph,
an average radius of curvature for the curved folds may easily be calculated.
In embodiments
of our invention, we have found that the radius of curvature for the curved
folds averages
about 1.2 mm, with the radiuses ranging between about 0.5 mm and about 2.0 mm.
As discussed above, the curved folds are formed as a result of a localized
strain field that
arises when a creping operation is performed with an angled warp yarn knuckle
fabric
according to our invention. For a given absorbent sheet, a normalized fold
curvature ratio
can be calculated as the radius of curvature for a curved fold divided by a
radius of a circle
drawn within the projected regions. The lower the normalized fold curvature
ratio, the more
effective the strain field has been to curve the folds. And, we believe that
with a more
46
CA 03024517 2018-11-15
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effectively formed fold curvature, the absorbency and softness of the
absorbent sheet are
improved.
An example of calculating the normalized fold curvature ratio for absorbent
sheet will now be
described with reference to Figures 30A and 30B. An absorbent sheet according
to our
invention is shown in Figure 30A, and a commercially-available comparison
absorbent sheet
is shown in Figure 30B. In Figure 30A, an arc has been drawn to match one of
the curved
folds. From this and other similarly drawn arcs, the average radius of
curvature for the
curved folds may be calculated, as discussed above. Similarly, an arc has been
drawn in
Figure 30B to match a slight curvature that can be seen in the fold
formations, and an average
radius for this absorbent sheet may thereby be calculated from this and
similar arcs. The full
circles in Figures 30A and 30B have been drawn within the projected regions,
with opposite
points of the circles aligning with points on opposite sides of the projected
regions in which
the curved fold formations appear. The circles are the maximum size that can
be fit within
the projected regions, and the radiuses of these circles are therefore half of
the distance across
the projected regions in the CD of the absorbent sheet. The normalized fold
curvature ratio
can then be calculated for the absorbent sheets shown in Figures 30A and 30B
as the ratio of
the calculated average radius of curvature and the radius of curvature for the
maximum circle
size within the projected regions. For the absorbent sheet according to our
invention shown
in Figure 30A, the calculated average radius of curvature is about 1.2 mm, and
the
normalized fold curvature ratio is about 1.9. On the other hand, for the
comparison absorbent
sheet shown in Figure 30B, the calculated average radius of curvature is about
4.55 and the
normalized fold curvature ratio is about 4.5. Thus, it is evident that the
absorbent sheet
according to our invention has both more of curvature in its fold formation
than the
comparison sheet, and that the curvature is much closer to the maximum
curvature that was
possible in the formation of the absorbent sheet.
In embodiments of our invention, the normalized fold curvature ratio is less
than about 4, and
more particularly, from about 0.5 to about 4. In more specific embodiments,
the normalized
fold curvature ratio is from about 1 to about 3. As evidence by the absorbent
sheet shown in
Figure 30A, embodiments of our invention may have a specific normalized fold
curvature
ratio around about 2. When the normalized fold curvature ratio is in these
ranges, we believe
that a significant amount of fiber mobilization has occurred for the given
fabric. Thus, as
47
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also discussed above, the fiber mobilization leads to better properties in the
paper product,
such as good absorbency.
Although this invention has been described in certain specific exemplary
embodiments, many
additional modifications and variations would be apparent to those skilled in
the art in light of
this disclosure. It is, therefore, to be understood that this invention may be
practiced
otherwise than as specifically described. Thus, the exemplary embodiments of
the invention
should be considered in all respects to be illustrative and not restrictive,
and the scope of the
invention to be determined by any claims supportable by this application and
the equivalents
thereof, rather than by the foregoing description.
Industrial Applicability
The invention can be used to produce desirable paper products such as hand
towels or toilet
paper. Thus, the invention is applicable to the paper products industry.
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