Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIBROUS STRUCTURES THAT EXHIBIT CONSUMER RELEVANT PROPERTY VALUES
FIELD OF THE INVENTION
The present invention relates to fibrous structures that exhibit a 4-Factor
Consumer
Relevant Property Value and more particularly to fibrous structures that
exhibit a 5-Factor and/or
6-Factor Consumer Relevant Property Value.
BACKGROUND OF THE INVENTION
Fibrous structures have exhibited various consumer relevant property values
for various
properties, such as absorbent capacity, initial total wet tensile, dry tensile
modulus, basis weight
wet caliper, residual water and lint. However, consumers still desire better
property values for
various consumer relevant properties, especially without negatively impacting
other consumer
relevant property values and hopefully increasing at least some of the other
consumer relevant
property values.
In the area of consumer products, especially consumer products employing
fibrous
structures, such as sanitary tissue products, consumers integrate multiple
properties to assess their
overall impression of a product. For the product developer it often becomes a
trade-off between
improving one relevant property albeit at the expense of another relevant
property. A classic
example of this dilemma is increasing the softness of a product, an
improvement to the
consumer, while also increasing the product's lint, a negative to the
consumer. The challenge to
the product developer is to maximize the overall impression of a product by
maximizing the
integration of these multiple properties.
Further challenging the product developer is that the relative effect of
increasing or
decreasing a particular property has a nonlinear effect on the consumer's
impression. For
example, increasing the wet durability of a product, such as the Wet CD TEA,
is consumer
beneficial, but continuing to increase that value eventually has diminishing
returns to the
consumer for the consumer is eventually able to perform all the consumer's
desired tasks with
the product, therefore there would be no need to increase the value beyond
that point at that
time. A further example is in the area of lint. Between the consumer's
desirable goal of having
zero lint and a product with a very small amount of lint there is little
effect on the consumer's
impression of the product. However, as a product continues to increase the
amount of lint
observed by the consumer it begins to have a disproportionately negative
impact on their
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impression of the product as the product no longer meets her needs for her
desired tasks. Thus,
the effect of Dry Lint on the Dry Lint Score Value is a non-linear effect.
Accordingly, there is a need for fibrous structures that exhibit at least some
consumer
relevant property values that are better than known fibrous structures, and
more particularly there
is a need for a fibrous structure that exhibits a 4- and/or 5- and/or 6-factor
consumer relevant
property value that is better than known fibrous structures and processes for
making such new
fibrous structures.
SUMMARY OF THE INVENTION
The present invention fulfills the need described above by providing fibrous
structures
that exhibit at least some consumer relevant property values that are better
than known fibrous
structures, and more particularly there is a need for a fibrous structure that
exhibits a 4- and/or 5-
factor consumer relevant property value that is better than known fibrous
structures and
processes for making such new fibrous structures.
In one example of the present invention, a fibrous structure that exhibits a 4-
Factor
Consumer Relevant Property Value of at least 250, is provided.
In another example of the present invention, a fibrous structure that exhibits
a 5-Factor
Consumer Relevant Property Value of at least 340, is provided.
In yet another example of the present invention, a fibrous structure that
exhibits a 6-
Factor Consumer Relevant Property Value of at least 430, is provided.
In yet another example of the present invention, a single- or multi- ply
sanitary tissue
product comprising one or more fibrous structures according to the present
invention, is
provided.
Accordingly, the present invention provides a fibrous structure that exhibits
a 4-Factor
and/or 5-Factor and/or 6-Factor Consumer Relevant Property Value of at least
250 and/or at least
340 and/or at least 430.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic representation of an example of a fibrous structure
according to the
present invention;
Fig. 2 is a schematic, cross-sectional representation of Fig. 1 taken along
line 2-2;
Fig. 3 is a scanning electromicrophotograph of a cross-section of another
example of
fibrous structure according to the present invention;
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Fig. 4 is a schematic representation of another example of a fibrous structure
according to
the present invention;
Fig. 5 is a schematic, cross-sectional representation of another example of a
fibrous
structure according to the present invention;
Fig. 6 is a schematic, cross-sectional representation of another example of a
fibrous
structure according to the present invention;
Fig. 7 is a schematic representation of an example of a process for making a
fibrous
structure according to the present invention;
Fig. 8 is a schematic representation of an example of a patterned belt for use
in a process
according to the present invention;
Fig. 9 is a schematic representation of an example of a filament-forming hole
and fluid-
releasing hole from a suitable die useful in making a fibrous structure
according to the present
invention;
Fig. 10 is a diagram of a support rack utilized in the VFS Test Method
described herein;
Fig. 10A is a cross-sectional view of Fig. 10;
Fig. 11 is a diagram of a support rack cover utilized in the VFS Test Method
described
herein; and Fig. 1 1A is a cross-sectional view of Fig. 11.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
"Fibrous structure" as used herein means a structure that comprises one or
more filaments
and/or fibers. In one example, a fibrous structure according to the present
invention means an
orderly arrangement of filaments and/or fibers within a structure in order to
perform a function.
In another example, a fibrous structure according to the present invention is
a nonwoven.
Non-limiting examples of processes for making fibrous structures include known
wet-laid
papermaking processes and air-laid papermaking processes. Such processes
typically include
steps of preparing a fiber composition in the form of a suspension in a
medium, either wet, more
specifically aqueous medium, or dry, more specifically gaseous, i.e. with air
as medium. The
aqueous medium used for wet-laid processes is oftentimes referred to as a
fiber slurry. The
fibrous slurry is then used to deposit a plurality of fibers onto a forming
wire or belt such that an
embryonic fibrous structure is formed, after which drying and/or bonding the
fibers together
results in a fibrous structure. Further processing the fibrous structure may
be carried out such
that a finished fibrous structure is formed. For example, in typical
papermaking processes, the
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finished fibrous structure is the fibrous structure that is wound on the reel
at the end of
papermaking, and may subsequently be converted into a finished product, e.g. a
sanitary tissue
product.
The fibrous structures of the present invention may be homogeneous or may be
layered.
If layered, the fibrous structures may comprise at least two and/or at least
three and/or at least
four and/or at least five layers.
The fibrous structures of the present invention may be co-formed fibrous
structures.
"Co-formed fibrous structure" as used herein means that the fibrous structure
comprises a
mixture of at least two different materials wherein at least one of the
materials comprises a
filament, such as a polypropylene filament, and at least one other material,
different from the first
material, comprises a solid additive, such as a fiber and/or a particulate. In
one example, a co-
formed fibrous structure comprises solid additives, such as fibers, such as
wood pulp fibers
and/or absorbent gel materials and/or filler particles and/or particulate spot
bonding powders
and/or clays, and filaments, such as polypropylene filaments.
"Solid additive" as used herein means a fiber and/or a particulate.
"Particulate" as used herein means a granular substance or powder.
"Fiber" and/or "Filament" as used herein means an elongate particulate having
an
apparent length greatly exceeding its apparent width, i.e. a length to
diameter ratio of at least
about 10. For purposes of the present invention, a "fiber" is an elongate
particulate as described
above that exhibits a length of less than 5.08 cm (2 in.) and a "filament" is
an elongate particulate
as described above that exhibits a length of greater than or equal to 5.08 cm
(2 in.).
Fibers are typically considered discontinuous in nature. Non-limiting examples
of fibers
include wood pulp fibers and synthetic staple fibers such as polyester fibers.
Filaments are typically considered continuous or substantially continuous in
nature.
Filaments are relatively longer than fibers. Non-limiting examples of
filaments include
meltblown and/or spunbond filaments. Non-limiting examples of materials that
can be spun into
filaments include natural polymers, such as starch, starch derivatives,
cellulose and cellulose
derivatives, hemicellulose, hemicellulose derivatives, chitin, chitosan,
polyisoprene (cis and
trans), peptides, polyhydroxyalkanoates, and synthetic polymers including, but
not limited to,
thermoplastic polymer filaments comprising thermoplastic polymers, such as
polyesters, nylons,
polyolefins such as polypropylene filaments, polyethylene filaments, polyvinyl
alcohol and
polyvinyl alcohol derivatives, sodium polyacrylate (absorbent gel material)
filaments, and
copolymers of polyolefins such as polyethylene-octene, and biodegradable or
compostable
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thermoplastic fibers such as polylactic acid filaments, polyvinyl alcohol
filaments, and
polycaprolactone filaments. The filaments may be monocomponent or
multicomponent, such
as bicomponent filaments.
In one example of the present invention, "fiber" refers to papermaking fibers.
Papermaking fibers useful in the present invention include cellulosic fibers
commonly known
as wood pulp fibers. Applicable wood pulps include chemical pulps, such as
Kraft, sulfite,
and sulfate pulps, as well as mechanical pulps including, for example,
groundwood,
thermomechanical pulp and chemically modified thermomechanical pulp. Chemical
pulps,
however, may be preferred since they impart a superior tactile sense of
softness to tissue
sheets made therefrom. Pulps derived from both deciduous trees (hereinafter,
also referred to
as "hardwood") and coniferous trees (hereinafter, also referred to as
"softwood") may be
utilized. The hardwood and softwood fibers can be blended, or alternatively,
can be deposited
in layers to provide a stratified web. U.S. Pat. No. 4,300,981 and U.S. Pat.
No. 3,994,771
disclose layering of hardwood and softwood fibers. Also applicable to the
present invention
are fibers derived from recycled paper, which may contain any or all of the
above categories
as well as other non-fibrous materials such as fillers and adhesives used to
facilitate the
original papermaking.
In addition to the various wood pulp fibers, other cellulosic fibers such as
cotton
linters, rayon, lyocell and bagasse can be used in this invention. Other
sources of cellulose in
the form of fibers or capable of being spun into fibers include grasses and
grain sources.
"Sanitary tissue product" as used herein means a soft, low density (i.e. <
about 0.15
g/cm) web useful as a wiping implement for post-urinary and post-bowel
movement cleaning
(toilet tissue), for otorhinolaryngologic al discharges (facial tissue), and
multi-functional
absorbent and cleaning uses (absorbent towels). Non-limiting examples of
suitable sanitary
tissue products of the present invention include paper towels, bath tissue,
facial tissue,
napkins, baby wipes, adult wipes, wet wipes, cleaning wipes, polishing wipes,
cosmetic
wipes, car care wipes, wipes that comprise an active agent for performing a
particular
function, cleaning substrates for use with implements, such as a Swiffer
cleaning wipe/pad.
The sanitary tissue product may be convolutedly wound upon itself about a core
or without a
core to form a sanitary tissue product roll.
In one example, the sanitary tissue product of the present invention comprises
a
fibrous structure according to the present invention.
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The sanitary tissue products of the present invention may exhibit a basis
weight between
about 10 g/m2 to about 120 g/m2 and/or from about 15 g/m2 to about 110 g/m2
and/or from about
20 g/m2 to about 100 g/m2 and/or from about 30 to 90 g/m2. In addition, the
sanitary tissue
product of the present invention may exhibit a basis weight between about 40
g/m2 to about 120
g/m2 and/or from about 50 g/m2 to about 110 g/m2 and/or from about 55 g/m2 to
about 105 g/m2
and/or from about 60 to 100 g/m2.
The sanitary tissue products of the present invention may exhibit a total dry
tensile
strength of at least 59 g/cm (150 g/in) and/or from about 78 g/cm (200 g/in)
to about 394 g/cm
(1000 g/in) and/or from about 98 g/cm (250 g/in) to about 335 g/cm (850 g/in).
In addition, the
sanitary tissue product of the present invention may exhibit a total dry
tensile strength of at least
196 g/cm (500 g/in) and/or from about 196 g/cm (500 g/in) to about 394 g/cm
(1000 g/in) and/or
from about 216 g/cm (550 g/in) to about 335 g/cm (850 g/in) and/or from about
236 g/cm (600
g/in) to about 315 g/cm (800 g/in). In one example, the sanitary tissue
product exhibits a total
dry tensile strength of less than about 394 g/cm (1000 g/in) and/or less than
about 335 g/cm (850
g/in).
In another example, the sanitary tissue products of the present invention may
exhibit a
total dry tensile strength of at least 196 g/cm (500 g/in) and/or at least 236
g/cm (600 g/in) and/or
at least 276 g/cm (700 g/in) and/or at least 315 g/cm (800 g/in) and/or at
least 354 g/cm (900
g/in) and/or at least 394 g/cm (1000 g/in) and/or from about 315 g/cm (800
g/in) to about 1968
g/cm (5000 g/in) and/or from about 354 g/cm (900 g/in) to about 1181 g/cm
(3000 g/in) and/or
from about 354 g/cm (900 g/in) to about 984 g/cm (2500 g/in) and/or from about
394 g/cm (1000
g/in) to about 787 g/cm (2000 g/in).
The sanitary tissue products of the present invention may exhibit an initial
total wet
tensile strength of less than about 78 g/cm (200 g/in) and/or less than about
59 g/cm (150 g/in)
and/or less than about 39 g/cm (100 g/in) and/or less than about 29 g/cm (75
g/in).
The sanitary tissue products of the present invention may exhibit an initial
total wet
tensile strength of at least 118 g/cm (300 g/in) and/or at least 157 g/cm (400
g/in) and/or at least
196 g/cm (500 g/in) and/or at least 236 g/cm (600 g/in) and/or at least 276
g/cm (700 g/in)
and/or at least 315 g/cm (800 g/in) and/or at least 354 g/cm (900 g/in) and/or
at least 394 g/cm
(1000 g/in) and/or from about 118 g/cm (300 g/in) to about 1968 g/cm (5000
g/in) and/or from
about 157 g/cm (400 g/in) to about 1181 g/cm (3000 g/in) and/or from about 196
g/cm (500 g/in)
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to about 984 g/cm (2500 g/in) and/or from about 196 g/cm (500 g/in) to about
787 g/cm (2000
g/in) and/or from about 196 g/cm (500 g/in) to about 591 g/cm (1500 g/in).
The sanitary tissue products of the present invention may exhibit a density
(measured at
95 g/in2) of less than about 0.60 g/cm3 and/or less than about 0.30 g/cm3
and/or less than about
0.20 g/cm3 and/or less than about 0.10 g/cm3 and/or less than about 0.07 g/cm3
and/or less than
about 0.05 g/cm3 and/or from about 0.01 g/cm3 to about 0.20 g/cm3 and/or from
about 0.02 g/cm3
to about 0.10 g/cm3.
The sanitary tissue products of the present invention may exhibit a Vertical
Full Sheet
(VFS) value as determined by the Vertical Full Sheet (VFS) Test Method
described herein of at
least 5 g/g and/or at least 7 g/g and/or at least 9 g/g and/or from about 9
g/g to about 30 g/g
and/or to about 25 g/g and/or to about 20 g/g and/or to about 17 g/g.
The sanitary tissue products of the present invention may be in the form of
sanitary tissue
product rolls. Such sanitary tissue product rolls may comprise a plurality of
connected, but
perforated sheets of fibrous structure, that are separably dispensable from
adjacent sheets. In one
example, one or more ends of the roll of sanitary tissue product may comprise
an adhesive and/or
dry strength agent to mitigate the loss of fibers, especially wood pulp fibers
from the ends of the
roll of sanitary tissue product.
The sanitary tissue products of the present invention may comprises additives
such as
softening agents, temporary wet strength agents, permanent wet strength
agents, bulk softening
agents, lotions, silicones, wetting agents, latexes, especially surface-
pattern-applied latexes, dry
strength agents such as carboxymethylcellulose and starch, and other types of
additives suitable
for inclusion in and/or on sanitary tissue products.
"Weight average molecular weight" as used herein means the weight average
molecular
weight as determined using gel permeation chromatography according to the
protocol found in
Colloids and Surfaces A. Physico Chemical & Engineering Aspects, Vol. 162,
2000, pg. 107-
121.
"Basis Weight" as used herein is the weight per unit area of a sample reported
in lbs/3000
ft2 or g/m2.
"Machine Direction" or "MD" as used herein means the direction parallel to the
flow of
the fibrous structure through the fibrous structure making machine and/or
sanitary tissue product
manufacturing equipment.
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"Cross Machine Direction" or "CD" as used herein means the direction parallel
to the
width of the fibrous structure making machine and/or sanitary tissue product
manufacturing
equipment and perpendicular to the machine direction.
"Ply" as used herein means an individual, integral fibrous structure.
"Plies" as used herein means two or more individual, integral fibrous
structures disposed
in a substantially contiguous, face-to-face relationship with one another,
forming a multi-ply
fibrous structure and/or multi-ply sanitary tissue product. It is also
contemplated that an
individual, integral fibrous structure can effectively form a multi-ply
fibrous structure, for
example, by being folded on itself.
"Consumer Relevant Property Value" as used herein is the sum of 4, 5, or 6
specific
property values of a fibrous structure.
"4-Factor Consumer Relevant Property Value" as used herein is the sum of Wet
Bulk
Density value, VFS Absorbent Capacity value, Wet CD TEA value, and Geometric
Mean Dry
Modulus value.
"5-Factor Consumer Relevant Property Value" as used herein is the sum of Wet
Bulk
Density value, VFS Absorbent Capacity value, Wet CD TEA value, Geometric Mean
Dry
Modulus value, and Residual Water value as measured according to their
specific test methods
described herein.
"6-Factor Consumer Relevant Property Value" as used herein is the sum of Wet
Bulk
Density value, VFS Absorbent Capacity value, Wet CD TEA value, Geometric Mean
Dry
Modulus value, Residual Water value, and Dry Lint Score value as measured
according to their
specific test methods described herein.
The consumer relevant properties disclosed herein convert analytical measures
into their
Consumer Relevant Property Values via equations that differ depending on the
property. Each
property has a minimum value of zero and a maximum value of 100. It is
appropriate for some
of these equations to be nonlinear because a consumer's response to these
properties is also
nonlinear. The 4-Factor, 5-Factor, and 6-Factor Consumer Relevant Property
values represent
the integration of these properties into a fibrous structure. The higher the 4-
Factor and/or 5-
Factor and/or 6-Factor Consumer Relevant Property value, the better the
fibrous structure.
"Wet Bulk Density value" as used herein is the sum of the following equation
that utilizes
the basis weight of a fibrous structure divided by the fibrous structure's wet
caliper as measured
according to their test methods described herein:
Wet Bulk Density value = -639.44(basis weight/wet caliper) + 119.
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The minimum Wet Bulk Density value is 0 and the maximum is 100. The Wet Bulk
Density
value relates to the bulk of fibrous structures according to the present
invention.
"VFS Absorbent Capacity value" as used herein is the difference of the
following
equation that utilizes the VFS of a fibrous structure as measured according to
its test method
described herein:
VFS Absorbent Capacity value = 59.055Ln(VFS) - 74.697.
The minimum VFS Absorbent Capacity value is 0 and the maximum is 100. The VFS
Absorbent
Capacity value relates to the absorbent capacity of fibrous structures
according to the present
invention.
"Wet CD TEA value" as used herein is the difference of the following equation
that
utilizes the Wet CD TEA of a fibrous structure as measured according to its
test method
described herein:
Wet CD TEA value = 26.158Ln(Wet CD TEA) - 46.49.
The minimum Wet CD TEA value is 0 and the maximum is 100. The Wet CD TEA value
relates
to the wet strength of fibrous structures according to the present invention.
"Geometric Mean (GM) Dry Modulus value" as used herein is the sum of the
following
equation that utilizes the GM Dry Modulus of a fibrous structure as measured
according to its test
method described herein:
GM Dry Modulus Value = 50.478Ln(GM Dry Modulus) + 418.49.
The minimum GM Dry Modulus value is 0 and the maximum is 100. The GM Dry
Modulus
value relates to the softness of fibrous structures according to the present
invention.
"Residual Water value" as used herein is the sum of the following equation
that utilizes
the Residual Water of a fibrous structure as measured according to its test
method described
herein:
Residual Water value = -360(Residual Water) + 112.
The minimum Residual Water value is 0 and the maximum is 100. The Residual
Water value
relates to the surface drying of fibrous structures according to the present
invention.
"Dry Lint Score value" as used herein is the sum of the following equation
that utilizes
the Dry Lint Score of a fibrous structure as measured according to its test
method described
herein:
Dry Lint Score value = -11.194(Dry Lint Score)2 + 12.505(Dry Lint Score) +
96.227.
The minimum Dry Lint Score value is 0 and the maximum is 100. The Dry Lint
Score value
relates to the low linting of fibrous structures according to the present
invention.
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As used herein, the articles "a" and "an" when used herein, for example, an
anionic
surfactant" or "a fiber" is understood to mean one or more of the material
that is claimed or
described.
All percentages and ratios are calculated by weight unless otherwise
indicated. All
percentages and ratios are calculated based on the total composition unless
otherwise indicated.
Unless otherwise noted, all component or composition levels are in reference
to the active
level of that component or composition, and are exclusive of impurities, for
example, residual
solvents or by-products, which may be present in commercially available
sources.
Fibrous Structure
It has surprisingly been found that the fibrous structures of the present
invention exhibit a
4-Factor and/or 5-Factor and/or 6-Factor Consumer Relevant Property Value that
has never been
achieved before and that consumers desire.
In one example, the fibrous structures of the present invention exhibit a 4-
Factor
Consumer Relevant Property Value of at least 250 and/or at least 275 and/or at
least 300.
In another example, the fibrous structures of the present invention exhibit a
5-Factor
Consumer Relevant Property Value of at least 340 and/or at least 360 and/or at
least 375.
In yet another example, the fibrous structures of the present invention
exhibit a 6-Factor
Consumer Relevant Property Value of at least 430 and/or at least 440 and/or at
least 450.
The fibrous structures of the present invention may comprise a plurality of
filaments, a
plurality of solid additives, such as fibers, and a mixture of filaments and
solid additives.
Such fibrous structures have been found to exhibit consumer-recognizable
beneficial
absorbent capacity. In one example, the fibrous structures comprise a
plurality of solid additives,
for example fibers. In another example, the fibrous structures comprise a
plurality of filaments.
In yet another example, the fibrous structures comprise a mixture of filaments
and solid
additives, such as fibers.
Figs. 1 and 2 show schematic representations of an example of a fibrous
structure in
accordance with the present invention. As shown in Figs. 1 and 2, the fibrous
structure 10 may
be a co-formed fibrous structure. The fibrous structure 10 comprises a
plurality of filaments 12,
such as polypropylene filaments, and a plurality of solid additives, such as
wood pulp fibers 14.
The filaments 12 may be randomly arranged as a result of the process by which
they are spun
and/or formed into the fibrous structure 10. The wood pulp fibers 14, may be
randomly
dispersed throughout the fibrous structure 10 in the x-y plane. The wood pulp
fibers 14 may be
non-randomly dispersed throughout the fibrous structure in the z-direction. In
one example (not
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shown), the wood pulp fibers 14 are present at a higher concentration on one
or more of the
exterior, x-y plane surfaces than within the fibrous structure along the z-
direction.
Fig. 3 shows a cross-sectional, SEM microphotograph of another example of a
fibrous
structure 10a in accordance with the present invention shows a fibrous
structure 10a comprising
a non-random, repeating pattern of microregions 15a and 15b. The microregion
15a (typically
referred to as a "pillow") exhibits a different value of a common intensive
property than
microregion 15b (typically referred to as a "knuckle"). In one example, the
microregion 15b is a
continuous or semi-continuous nextwork and the microregion 15a are discrete
regions within the
continuous or semi-continuous network. The common intensive property may be
caliper. In
another example, the common intensive property may be density.
As shown in Fig. 4, another example of a fibrous structure in accordance with
the present
invention is a layered fibrous structure 10b. The layered fibrous structure
10b comprises a first
layer 16 comprising a plurality of filaments 12, such as polypropylene
filaments, and a plurality
of solid additives, in this example, wood pulp fibers 14. The layered fibrous
structure 10b further
comprises a second layer 18 comprising a plurality of filaments 20, such as
polypropylene
filaments. In one example, the first and second layers 16, 18, respectively,
are sharply defined
zones of concentration of the filaments and/or solid additives. The plurality
of filaments 20 may
be deposited directly onto a surface of the first layer 16 to form a layered
fibrous structure that
comprises the first and second layers 16, 18, respectively.
Further, the layered fibrous structure 10b may comprise a third layer 22, as
shown in Fig.
4. The third layer 22 may comprise a plurality of filaments 24, which may be
the same or
different from the filaments 20 and/or 16 in the second 18 and/or first 16
layers. As a result of
the addition of the third layer 22, the first layer 16 is positioned, for
example sandwiched,
between the second layer 18 and the third layer 22. The plurality of filaments
24 may be
deposited directly onto a surface of the first layer 16, opposite from the
second layer, to form the
layered fibrous structure 10b that comprises the first, second and third
layers 16, 18, 22,
respectively.
As shown in Fig. 5, a cross-sectional schematic representation of another
example of a
fibrous structure in accordance with the present invention comprising a
layered fibrous structure
10c is provided. The layered fibrous structure 10c comprises a first layer 26,
a second layer 28
and optionally a third layer 30. The first layer 26 comprises a plurality of
filaments 12, such as
polypropylene filaments, and a plurality of solid additives, such as wood pulp
fibers 14. The
second layer 28 may comprise any suitable filaments, solid additives and/or
polymeric films. In
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one example, the second layer 28 comprises a plurality of filaments 34. In one
example, the
filaments 34 comprise a polymer selected from the group consisting of:
polysaccharides,
polysaccharide derivatives, polyvinylalcohol, polyvinylalcohol derivatives and
mixtures thereof.
In another example of a fibrous structure in accordance with the present
invention, instead
of being layers of fibrous structure 10c, the material forming layers 26, 28
and 30, may be in the
form of plies wherein two or more of the plies may be combined to form a
fibrous structure. The
plies may be bonded together, such as by thermal bonding and/or adhesive
bonding, to form a
multi-ply fibrous structure.
Another example of a fibrous structure of the present invention in accordance
with the
present invention is shown in Fig. 6. The fibrous structure 10d may comprise
two or more plies,
wherein one ply 36 comprises any suitable fibrous structure in accordance with
the present
invention, for example fibrous structure 10 as shown and described in Figs. 1
and 2 and another
ply 38 comprising any suitable fibrous structure, for example a fibrous
structure comprising
filaments 12, such as polypropylene filaments. The fibrous structure of ply 38
may be in the
form of a net and/or mesh and/or other structure that comprises pores that
expose one or more
portions of the fibrous structure 10d to an external environment and/or at
least to liquids that may
come into contact, at least initially, with the fibrous structure of ply 38.
In addition to ply 38, the
fibrous structure 10d may further comprise ply 40. Ply 40 may comprise a
fibrous structure
comprising filaments 12, such as polypropylene filaments, and may be the same
or different from
the fibrous structure of ply 38.
Two or more of the plies 36, 38 and 40 may be bonded together, such as by
thermal
bonding and/or adhesive bonding, to form a multi-ply fibrous structure. After
a bonding
operation, especially a thermal bonding operation, it may be difficult to
distinguish the plies of
the fibrous structure 10d and the fibrous structure 10d may visually and/or
physically be a similar
to a layered fibrous structure in that one would have difficulty separating
the once individual
plies from each other. In one example, ply 36 may comprise a fibrous structure
that exhibits a
basis weight of at least about 15 g/m2 and/or at least about 20 g/m2 and/or at
least about 25 g/m2
and/or at least about 30 g/m2 up to about 120 g/m2 and/or 100 g/m2 and/or 80
g/m2 and/or 60
g/m2 and the plies 38 and 42, when present, independently and individually,
may comprise
fibrous structures that exhibit basis weights of less than about 10 g/m2
and/or less than about 7
g/m2 and/or less than about 5 g/m2 and/or less than about 3 g/m2 and/or less
than about 2 g/m2
and/or to about 0 g/m2 and/or 0.5 g/m2.
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Plies 38 and 40, when present, may help retain the solid additives, in this
case the wood
pulp fibers 14, on and/or within the fibrous structure of ply 36 thus reducing
lint and/or dust (as
compared to a single-ply fibrous structure comprising the fibrous structure of
ply 36 without the
plies 38 and 40) resulting from the wood pulp fibers 14 becoming free from the
fibrous structure
of ply 36.
The fibrous structures of the present invention may comprise any suitable
amount of
filaments and any suitable amount of solid additives. For example, the fibrous
structures may
comprise from about 10% to about 70% and/or from about 20% to about 60% and/or
from about
30% to about 50% by dry weight of the fibrous structure of filaments and from
about 90% to
about 30% and/or from about 80% to about 40% and/or from about 70% to about
50% by dry
weight of the fibrous structure of solid additives, such as wood pulp fibers.
The filaments and solid additives of the present invention may be present in
fibrous
structures according to the present invention at weight ratios of filaments to
solid additives of
from at least about 1:1 and/or at least about 1:1.5 and/or at least about 1:2
and/or at least about
1:2.5 and/or at least about 1:3 and/or at least about 1:4 and/or at least
about 1:5 and/or at least
about 1:7 and/or at least about 1:10.
The fibrous structures of the present invention and/or any sanitary tissue
products
comprising such fibrous structures may be subjected to any post-processing
operations such as
embossing operations, printing operations, tuft-generating operations, thermal
bonding
operations, ultrasonic bonding operations, perforating operations, surface
treatment operations
such as application of lotions, silicones and/or other materials and mixtures
thereof.
Non-limiting examples of suitable polypropylenes for making the filaments of
the present
invention are commercially available from Lyondell-Basell and Exxon-Mobil.
Any hydrophobic or non-hydrophilic materials within the fibrous structure,
such as
polypropylene filaments, may be surface treated and/or melt treated with a
hydrophilic modifier.
Non-limiting examples of surface treating hydrophilic modifiers include
surfactants, such as
Triton X-100. Non-limiting examples of melt treating hydrophilic modifiers
that are added to the
melt, such as the polypropylene melt, prior to spinning filaments, include
hydrophilic modifying
melt additives such as VW351 and/or 5-1416 commercially available from
Polyvel, Inc. and
Irgasurf commercially available from Ciba. The hydrophilic modifier may be
associated with the
hydrophobic or non-hydrophilic material at any suitable level known in the
art. In one example,
the hydrophilic modifier is associated with the hydrophobic or non-hydrophilic
material at a level
of less than about 20% and/or less than about 15% and/or less than about 10%
and/or less than
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about 5% and/or less than about 3% to about 0% by dry weight of the
hydrophobic or non-
hydrophilic material.
The fibrous structures of the present invention may include optional
additives, each, when
present, at individual levels of from about 0% and/or from about 0.01% and/or
from about 0.1%
and/or from about 1% and/or from about 2% to about 95% and/or to about 80%
and/or to about
50% and/or to about 30% and/or to about 20% by dry weight of the fibrous
structure. Non-
limiting examples of optional additives include permanent wet strength agents,
temporary wet
strength agents, dry strength agents such as carboxymethylcellulose and/or
starch, softening
agents, lint reducing agents, opacity increasing agents, wetting agents, odor
absorbing agents,
perfumes, temperature indicating agents, color agents, dyes, osmotic
materials, microbial growth
detection agents, antibacterial agents and mixtures thereof.
The fibrous structure of the present invention may itself be a sanitary tissue
product. It
may be convolutedly wound about a core to form a roll. It may be combined with
one or more
other fibrous structures as a ply to form a multi-ply sanitary tissue product.
In one example, a co-
formed fibrous structure of the present invention may be convolutedly wound
about a core to
form a roll of co-formed sanitary tissue product. The rolls of sanitary tissue
products may also be
coreless.
To further illustrate the fibrous structures of the present invention, Table 1
sets forth the
4-Factor, 5-Factor, and 6-Factor Consumer Relevant Property Values of known
and/or
commercially available fibrous structures and a fibrous structure in
accordance with the present
invention.
Table 1
Fibrous Structure 4-Factor 5-Factor 6-Factor
Invention 314 386 460
Oasis a by First 199 249 345
Quality
BountyR Basic 187 182 279
Bountya 196 237 334
Bountya ExtraSoft 114 241 319
P&G Prior Filament- 173 216 312
containing Substrate
Sparkle a by Georgia 80 121 212
Pacific (conventional)
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Scott by Kimberly 189 263 360
Clark (UCTAD)
VivaR by Kimberly 238 326 423
Clark (Double
recreped)
Viva o by Kimberly 218 304 310
Clark (Airlaid)
Duramax 228 271 368
(Spunbond/wet
laid/hydroentangled)
Concert (Thermally 206 283 390
bonded airlaid)
KleenexR Premier by 215 294 390
Kimberly Clark
(Airlace)
Method For Making A Fibrous Structure
A non-limiting example of a method for making a fibrous structure according to
the
present invention is represented in Fig. 7. The method shown in Fig. 7
comprises the step of
mixing a plurality of solid additives 14 with a plurality of filaments 12. In
one example, the solid
additives 14 are wood pulp fibers, such as SSK fibers and/or Eucalytpus
fibers, and the filaments
12 are polypropylene filaments. The solid additives 14 may be combined with
the filaments 12,
such as by being delivered to a stream of filaments 12 from a hammermill 42
via a solid additive
spreader 44 to form a mixture of filaments 12 and solid additives 14. The
filaments 12 may be
created by meltblowing from a meltblow die 46. The mixture of solid additives
14 and filaments
12 are collected on a collection device, such as a belt 48 to form a fibrous
structure 50. The
collection device may be a patterned and/or molded belt that results in the
fibrous structure
exhibiting a surface pattern, such as a non-random, repeating pattern of
microregions. The
patterned belt may have a three-dimensional pattern on it that gets imparted
to the fibrous
structure 50 during the process. For example, the patterned belt 52, as shown
in Fig. 8, may
comprise a reinforcing structure, such as a fabric 54, upon which a polymer
resin 56 is applied in
a pattern. The pattern may comprise a continuous or semi-continuous network 58
of the polymer
resin 56 within which one or more discrete conduits 60 are arranged.
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In one example of the present invention, the fibrous structures are made using
a die
comprising at least one filament-forming hole, and/or 2 or more and/or 3 or
more rows of
filament-forming holes from which filaments are spun. At least one row of
holes contains 2 or
more and/or 3 or more and/or 10 or more filament-forming holes. In addition to
the filament-
forming holes, the die comprises fluid-releasing holes, such as gas-releasing
holes, in one
example air-releasing holes, that provide attenuation to the filaments formed
from the filament-
forming holes. One or more fluid-releasing holes may be associated with a
filament-forming
hole such that the fluid exiting the fluid-releasing hole is parallel or
substantially parallel (rather
than angled like a knife-edge die) to an exterior surface of a filament
exiting the filament-
forming hole. In one example, the fluid exiting the fluid-releasing hole
contacts the exterior
surface of a filament formed from a filament-forming hole at an angle of less
than 30 and/or less
than 20 and/or less than 10 and/or less than 5 and/or about 0 . One or more
fluid releasing
holes may be arranged around a filament-forming hole. In one example, one or
more fluid-
releasing holes are associated with a single filament-forming hole such that
the fluid exiting the
one or more fluid releasing holes contacts the exterior surface of a single
filament formed from
the single filament-forming hole. In one example, the fluid-releasing hole
permits a fluid, such
as a gas, for example air, to contact the exterior surface of a filament
formed from a filament-
forming hole rather than contacting an inner surface of a filament, such as
what happens when a
hollow filament is formed.
In one example, the die comprises a filament-forming hole positioned within a
fluid-
releasing hole. The fluid-releasing hole 62 may be concentrically or
substantially concentrically
positioned around a filament-forming hole 64 such as is shown in Fig. 9.
After the fibrous structure 50 has been formed on the collection device, the
fibrous
structure 50 may be calendered, for example, while the fibrous structure is
still on the collection
device. In addition, the fibrous structure 50 may be subjected to post-
processing operations such
as embossing, thermal bonding, tuft-generating operations, moisture-imparting
operations, and
surface treating operations to form a finished fibrous structure. One example
of a surface treating
operation that the fibrous structure may be subjected to is the surface
application of an
elastomeric binder, such as ethylene vinyl acetate (EVA), latexes, and other
elastomeric binders.
Such an elastomeric binder may aid in reducing the lint created from the
fibrous structure during
use by consumers. The elastomeric binder may be applied to one or more
surfaces of the fibrous
structure in a pattern, especially a non-random, repeating pattern of
microregions, or in a manner
that covers or substantially covers the entire surface(s) of the fibrous
structure.
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In one example, the fibrous structure 50 and/or the finished fibrous structure
may be
combined with one or more other fibrous structures. For example, another
fibrous structure, such
as a filament-containing fibrous structure, such as a polypropylene filament
fibrous structure may
be associated with a surface of the fibrous structure 50 and/or the finished
fibrous structure. The
polypropylene filament fibrous structure may be formed by meltblowing
polypropylene filaments
(filaments that comprise a second polymer that may be the same or different
from the polymer of
the filaments in the fibrous structure 50) onto a surface of the fibrous
structure 50 and/or finished
fibrous structure. In another example, the polypropylene filament fibrous
structure may be
formed by meltblowing filaments comprising a second polymer that may be the
same or different
from the polymer of the filaments in the fibrous structure 50 onto a
collection device to form the
polypropylene filament fibrous structure. The polypropylene filament fibrous
structure may then
be combined with the fibrous structure 50 or the finished fibrous structure to
make a two-ply
fibrous structure - three-ply if the fibrous structure 50 or the finished
fibrous structure is
positioned between two plies of the polypropylene filament fibrous structure
like that shown in
Fig. 6 for example. The polypropylene filament fibrous structure may be
thermally bonded to the
fibrous structure 50 or the finished fibrous structure via a thermal bonding
operation.
In yet another example, the fibrous structure 50 and/or finished fibrous
structure may be
combined with a filament-containing fibrous structure such that the filament-
containing fibrous
structure, such as a polysaccharide filament fibrous structure, such as a
starch filament fibrous
structure, is positioned between two fibrous structures 50 or two finished
fibrous structures like
that shown in Fig. 6 for example.
In still another example, two plies of fibrous structure 50 comprising a non-
random,
repeating pattern of microregions may be associated with one another such that
protruding
microregions, such as pillows, face inward into the two-ply fibrous structure
formed.
The process for making fibrous structure 50 may be close coupled (where the
fibrous
structure is convolutedly wound into a roll prior to proceeding to a
converting operation) or
directly coupled (where the fibrous structure is not convolutedly wound into a
roll prior to
proceeding to a converting operation) with a converting operation to emboss,
print, deform,
surface treat, or other post-forming operation known to those in the art. For
purposes of the
present invention, direct coupling means that the fibrous structure 50 can
proceed directly into a
converting operation rather than, for example, being convolutedly wound into a
roll and then
unwound to proceed through a converting operation.
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The process of the present invention may include preparing individual rolls of
fibrous
structure and/or sanitary tissue product comprising such fibrous structure(s)
that are suitable for
consumer use.
Non-limiting Example of Process for Making a Fibrous Structure of the Present
Invention:
A 20%:27.5%47.5%:5% blend of Lyondell-Basell PH835 polypropylene : Lyondell-
Basell Metocene MF650W polypropylene : Exxon-Mobil PP3546 polypropylene :
Polyvel S-
1416 wetting agent is dry blended, to form a melt blend. The melt blend is
heated to 475 F
through a melt extruder. A 15.5 inch wide Biax 12 row spinnerette with 192
nozzles per cross-
direction inch, commercially available from Biax Fiberfilm Corporation, is
utilized. 40 nozzles
per cross-direction inch of the 192 nozzles have a 0.018 inch inside diameter
while the remaining
nozzles are solid, i.e. there is no opening in the nozzle. Approximately 0.19
grams per hole per
minute (ghm) of the melt blend is extruded from the open nozzles to form
meltblown filaments
from the melt blend. Approximately 375 SCFM of compressed air is heated such
that the air
exhibits a temperature of 395 F at the spinnerette. Approximately 475 g /
minute of Golden Isle
(from Georgia Pacific) 4825 semi-treated SSK pulp is defibrillated through a
hammermill to
form SSK wood pulp fibers (solid additive). Air at 85-90 F and 85% relative
humidity (RH) is
drawn into the hammermill. Approximately 1200 SCFM of air carries the pulp
fibers to a solid
additive spreader. The solid additive spreader turns the pulp fibers and
distributes the pulp fibers
in the cross-direction such that the pulp fibers are injected into the
meltblown filaments in a
perpendicular fashion through a 4 inch x 15 inch cross-direction (CD) slot. A
forming box
surrounds the area where the meltblown filaments and pulp fibers are
commingled. This forming
box is designed to reduce the amount of air allowed to enter or escape from
this commingling
area; however, there is an additional 4 inch x 15 inch spreader opposite the
solid additive
spreader designed to add cooling air. Approximately 1000 SCFM of air at
approximately 80 F is
added through this additional spreader. A forming vacuum pulls air through a
collection device,
such as a patterned belt, thus collecting the commingled meltblown filaments
and pulp fibers to
form a fibrous structure comprising a pattern of non-random, repeating
microregions. The
fibrous structure formed by this process comprises about 75% by dry fibrous
structure weight of
pulp and about 25% by dry fibrous structure weight of meltblown filaments.
Optionally, a meltblown layer of the meltblown filaments can be added to one
or both
sides of the above formed fibrous structure. This addition of the meltblown
layer can help reduce
the lint created from the fibrous structure during use by consumers and is
preferably performed
prior to any thermal bonding operation of the fibrous structure. The meltblown
filaments for the
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exterior layers can be the same or different than the meltblown filaments used
on the opposite
layer or in the center layer(s).
The fibrous structure may be convolutedly wound to form a roll of fibrous
structure. The
end edges of the roll of fibrous structure may be contacted with a material to
create bond regions.
TEST METHODS:
Unless otherwise specified, all tests described herein including those
described under the
Definitions section and the following test methods are conducted on samples
that have been
conditioned in a conditioned room at a temperature of 73 F 4 F (about 23 C
2.2 C) and a
relative humidity of 50% 10% for 2 hours prior to the test. All tests are
conducted in such
conditioned room. Do not test samples that have defects such as wrinkles,
tears, holes, and like.
Consumer Relevant Property Value Test Method
A Consumer Relevant Property Value for a fibrous structure and/or sanitary
tissue
product comprising a fibrous structure is determined by measuring the
following properties of the
fibrous structure and/or sanitary tissue product comprising the fibrous
structure: VFS Absorbent
Capacity, Wet CD TEA, GM Dry Modulus, Wet Bulk (Basis Weight/Wet Caliper),
Residual
Water and Dry Lint Score.
Vertical Full Sheet (VFS) Test Method
The Vertical Full Sheet (VFS) test method determines the amount of distilled
water
absorbed and retained by a fibrous structure of the present invention. This
method is performed
by first weighing a sample of the fibrous structure to be tested (referred to
herein as the "dry
weight of the sample"), then thoroughly wetting the sample, draining the
wetted sample in a
vertical position and then reweighing (referred to herein as "wet weight of
the sample"). The
absorptive capacity of the sample is then computed as the amount of water
retained in units of
grams of water absorbed by the sample. When evaluating different fibrous
structure samples, the
same size of fibrous structure is used for all samples tested.
The apparatus for determining the VFS capacity of fibrous structures comprises
the
following:
1) An electronic balance with a sensitivity of at least 0.01 grams and a
minimum
capacity of 1200 grams. The balance should be positioned on a balance table
and slab to
minimize the vibration effects of floor/benchtop weighing. The balance should
also have a
special balance pan to be able to handle the size of the sample tested (i.e.;
a fibrous structure
sample of about 11 in. by 11 in. ). The balance pan can be made out of a
variety of materials.
Plexiglass is a common material used.
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2) A sample support rack (Figs. 10 and 10A) and sample support rack cover
(Figs. 11 and
11A) is also required. Both the rack and cover are comprised of a lightweight
metal frame, strung
with 0.012 in. diameter monofilament so as to form a grid as shown in Fig. 10.
The size of the
support rack and cover is such that the sample size can be conveniently placed
between the two.
The VFS test is performed in an environment maintained at 23 1 C and 50 2%
relative
humidity. A water reservoir or tub is filled with distilled water at 23 1 C
to a depth of 3
inches.
Eight 7.5 inch x 7.5 inch to 11 inch x 11 inch samples of a fibrous structure
to be tested
are carefully weighed on the balance to the nearest 0.01 grams. The dry weight
of each sample is
reported to the nearest 0.01 grams. The empty sample support rack is placed on
the balance with
the special balance pan described above. The balance is then zeroed (tared).
One sample is
carefully placed on the sample support rack. The support rack cover is placed
on top of the
support rack. The sample (now sandwiched between the rack and cover) is
submerged in the
water reservoir. After the sample is submerged for 60 seconds, the sample
support rack and cover
are gently raised out of the reservoir.
The sample, support rack and cover are allowed to drain vertically (at angle
greater than
60 but less than 90 from horizontal) for 60 5 seconds, taking care not to
excessively shake or
vibrate the sample. While the sample is draining, the rack cover is removed
and excess water is
wiped from the support rack. The wet sample and the support rack are weighed
on the previously
tared balance. The weight is recorded to the nearest 0.01g. This is the wet
weight of the sample.
The procedure is repeated for with another sample of the fibrous structure,
however, the
sample is positioned on the support rack such that the sample is rotated 90
in plane compared to
the position of the first sample on the support rack.
The gram per fibrous structure sample absorptive capacity of the sample is
defined as
(wet weight of the sample - dry weight of the sample). The calculated VFS is
the average of the
absorptive capacities of the two samples of the fibrous structure.
Elongation, Tensile Strength, TEA and Modulus Test Methods
Cut at least eight 1 inch wide strips of the fibrous structure and/or sanitary
tissue product
to be tested in the machine direction. Cut at least eight 1 inch wide strips
in the cross direction. If
the machine direction and cross direction are not readily ascertainable, then
the cross direction
will be the strips that result in the lower peak load tensile. For the wet
measurements, each
sample is wetted by submerging the sample in a distilled water bath for 30
seconds. The wet
property of the wet sample is measured within 30 seconds of removing the
sample from the bath.
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For the actual measurements of the properties, use a Thwing-Albert Intelect II
Standard
Tensile Tester (Thwing-Albert Instrument Co. of Philadelphia, Pa.). Insert the
flat face clamps
into the unit and calibrate the tester according to the instructions given in
the operation manual of
the Thwing-Albert Intelect II. Set the instrument crosshead speed to 4.00
in/min and the 1st and
2nd gauge lengths to 4.00 inches. The break sensitivity is set to 20.0 grams
and the sample width
is set to 1.00 inch. The energy units are set to TEA and the tangent modulus
(Modulus) trap
setting is set to 38.1 g.
After inserting the fibrous structure sample strip into the two clamps, the
instrument
tension can be monitored. If it shows a value of 5 grams or more, the fibrous
structure sample
strip is too taut. Conversely, if a period of 2-3 seconds passes after
starting the test before any
value is recorded, the fibrous structure sample strip is too slack.
Start the tensile tester as described in the tensile tester instrument manual.
When the test
is complete, read and record the following with units of measure:
Peak Load Tensile (Tensile Strength) (g/in)
Peak Elongation (Elongation) (%)
Peak CD TEA (Wet CD TEA) (in-g/in2)
Tangent Modulus (Dry MD Modulus and Dry CD Modulus) (at 15g/cm)
Test each of the samples in the same manner, recording the above measured
values from
each test. Average the values for each property obtained from the samples
tested to obtain the
reported value for that property.
Calculations:
Geometric Mean (GM) Dry Modulus = Square Root of [Dry MD Modulus (at 15g/cm) x
Dry CD
Modulus (at 15g/cm)]
Basis Weight Test Method
Basis weight of a fibrous structure sample is measured by selecting twelve
(12) individual
fibrous structure samples and making two stacks of six individual samples
each. If the individual
samples are connected to one another vie perforation lines, the perforation
lines must be aligned
on the same side when stacking the individual samples. A precision cutter is
used to cut each
stack into exactly 3.5 in. x 3.5 in. squares. The two stacks of cut squares
are combined to make a
basis weight pad of twelve squares thick. The basis weight pad is then weighed
on a top loading
balance with a minimum resolution of 0.01 g. The top loading balance must be
protected from
air drafts and other disturbances using a draft shield. Weights are recorded
when the readings on
the top loading balance become constant. The Basis Weight is calculated as
follows:
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Basis Weight = Weight of basis weight pad (g) x 3000 ft2
(lbs/3000 ftt) 453.6 g/lbs x 12 samples x [12.25 in2 (Area of basis weight
pad)/144 in2]
Basis Weight = Weight of basis weight pad (g) x 10,000 cm2/m2
(g/m2) 79.0321 cm2 (Area of basis weight pad) x 12 samples
Wet Caliper Test Method
The Wet Caliper of a sample of fibrous structure and/or sanitary tissue
product
comprising a fibrous structure is determined by cutting a sample of the
fibrous structure and/or
sanitary tissue product comprising a fibrous structure such that it is larger
in size than a load foot
loading surface where the load foot loading surface has a circular surface
area of about 3.14 in2.
Each sample is wetted by submerging the sample in a distilled water bath for
30 seconds. The
caliper of the wet sample is measured within 30 seconds of removing the sample
from the bath.
The sample is then confined between a horizontal flat surface and the load
foot loading surface.
The load foot loading surface applies a confining pressure to the sample of 95
g/int. The caliper
is the resulting gap between the flat surface and the load foot loading
surface. Such
measurements can be obtained on a VIR Electronic Thickness Tester Model II
available from
Thwing-Albert Instrument Company, Philadelphia, PA. The caliper measurement is
repeated and
recorded at least five (5) times so that an average caliper can be calculated.
The result is reported
in mils.
Residual Water Test Method
The Residual Water Test Method determines the amount (in grams) of distilled
water
absorbed/left behind by a fibrous structure.
A 3 place top loading analytical balance (capacity of 650 g minimum) is used
with an 11
inch x 11 inch adjustable balance stand with a 6.25 inch diameter circle cut
in center to fit over a
4 inch diameter balance pan. The balance surface (a 6 inch diameter flat
surface made with #304
standard stainless steel) made to fit over the 4 inch diameter balance pan is
placed on the balance
pan. Wipe the balance surface to ensure that the balance surface is dry and
free of any debris or
contaminant. The balance surface is placed on the balance pan. Tare the
balance.
For 1-ply and 2-ply fibrous structure samples to be tested, slowly dispense
2.5 mL 0.1
mL of distilled water onto the center of the balance surface using a pipette
(capacity of 5 mL,
sensitivity of 0.1 mL, adjustable 1000 L - 5000 L). After dispensing, the
water should be
pooled in the center of the balance pan. If this is not occurring, level the
balance surface. Record
the accurate weight of the water.
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Prepare sample (11 inch x 11 inch maximum) for testing by placing the sample
in
between two Lexan plates (0.063 inch thick, 12.5 inch x 12.5 inch, with an 8
inch diameter circle
cut out), which are hinged together to form a sample template. Place the
sample template (with
sample in it) on the balance surface so that the 8 inch diameter cut out of
the sample template is
centered on the balance surface and the spot of distilled water. Allow the
sample to absorb the
distilled water for 30 0.1 seconds using a stop watch or digital timer
capable of measuring time
in seconds to the nearest 0.1 seconds. Remove the sample template (with sample
in it) using a
quick vertical motion. Record the weight (g) of the remaining water on the
balance surface.
After removing the sample from the Lexan plates, dry the balance surface and
Lexan plates.
Repeat for a total of ten samples.
Residual Water value is reported as the average weight of the remaining water
on the
balance surface for the ten samples. Record Residual Water value to the
nearest 0.1 g.
Lint Test Method:
The amount of lint generated from a fibrous structure sample is determined
with a
Sutherland Rub Tester. The Sutherland Rub Tester may be obtained from Testing
Machines, Inc.
(Amityville, N.Y., 1701). This tester uses a motor to rub a weighted felt 5
times over the fibrous
structure sample, while the fibrous structure sample is restrained in a
stationary position. The
Hunter Color L value is measured before and after the rub test. The difference
between these two
Hunter Color L values is then used to calculate a lint value.
i. Sample Preparation - The fibrous structure sample is first prepared by
removing and
discarding any product which might have been abraded in handling, e.g. on the
outside of the
roll. For products formed from multiple plies of fibrous structures, this test
can be used to make a
lint measurement on the multi-ply product, or, if the plies can be separated
without damaging the
specimen, a measurement can be taken on the individual plies making up the
product. If a given
sample differs from surface to surface, it is necessary to test both surfaces
and average the values
in order to arrive at a composite lint value. In some cases, products are made
from multiple-
plies of fibrous structures such that the facing-out surfaces are identical,
in which case it is only
necessary to test one surface. If both surfaces are to be tested, it is
necessary to obtain six
specimens for testing (Single surface testing only requires three specimens).
Each specimen
should be folded in half such that the crease is running along the cross
direction (CD) of the
fibrous structure sample. For two-surface testing, make up 3 samples with a
first surface "out"
and 3 with the second-side surface "out". Keep track of which samples are
first surface "out" and
which are second surface out.
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Obtain a 30 inch x 40 inch piece of Crescent #300 cardboard from Cordage Inc.
(800 E.
Ross Road, Cincinnati, Ohio, 45217). Using a paper cutter, cut out six pieces
of cardboard of
dimensions of 2.25 inch x 6 inch. Puncture two holes into each of the six
cards by forcing the
cardboard onto the hold down pins of the Sutherland Rub tester. Draw two lines
parallel to the
short dimension and down 1.125 inches from the top and bottom most edges on
the white side of
the cardboard. Carefully score the length of the line with a razor blade using
a straight edge as a
guide. Score it to a depth about half way through the thickness of the sheet.
This scoring allows
the cardboard/felt combination to fit tightly around the weight of the
Sutherland Rub tester. Draw
an arrow running parallel to the long dimension of the cardboard on this
scored side of the
cardboard.
Center and carefully place each of the 2.5 inch x 6 inch cardboard pieces on
top of the six
previously folded samples. Make sure the 6 inch dimension of the cardboard is
running parallel
to the machine direction (MD) of each of the fibrous structure samples. Center
and carefully
place each of the cardboard pieces on top of the three previously folded
samples. Once again,
make sure the 6 inch dimension of the cardboard is running parallel to the
machine direction
(MD) of each of the fibrous structure sample.
Fold one edge of the exposed portion of the fibrous structure sample onto the
back of the
cardboard. Secure this edge to the cardboard with adhesive tape obtained from
3M Inc. (3/4 inch
wide Scotch Brand, St. Paul, Minn.). Carefully grasp the other over-hanging
tissue edge and
snugly fold it over onto the back of the cardboard. While maintaining a snug
fit of the fibrous
structure sample onto the board, tape this second edge to the back of the
cardboard. Repeat this
procedure for each sample.
Turn over each sample and tape the cross direction edge of the fibrous
structure sample to
the cardboard. One half of the adhesive tape should contact the fibrous
structure sample while the
other half is adhering to the cardboard. Repeat this procedure for each of the
samples. If the
fibrous structure sample breaks, tears, or becomes frayed at any time during
the course of this
sample preparation procedure, discard and make up a new sample with a new
fibrous structure
sample strip.
There will now be 3 first-side surface "out" samples on cardboard and 3 second-
side
surface "out" samples on cardboard.
ii. Felt Preparation - Cut six pieces of black felt (F-55 or equivalent from
New England
Gasket, 550 Broad Street, Bristol, Conn. 06010) to the dimensions of 2.25 inch
x 8.5 inch x
0.0625 inch. Place the felt on top of the unscored, green side of the
cardboard such that the long
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edges of both the felt and cardboard are parallel and in alignment. Make sure
the fluffy side of
the felt is facing up. Also allow about 0.5 inches to overhang the top and
bottom most edges of
the cardboard. Snugly fold over both overhanging felt edges onto the backside
of the cardboard
with Scotch brand tape. Prepare a total of six of these felt/cardboard
combinations.
iii. Care of 4 Pound Weight - A four pound weight is used. The four pound
weight has
four square inches of effective contact area providing a contact pressure of
one pound per square
inch. Since the contact pressure can be changed by alteration of the rubber
pads mounted on the
face of the weight, it is important to use only the rubber pads supplied by
the manufacturer
(Brown Inc., Mechanical Services Department, Kalamazoo, Mich.). These pads
must be replaced
if they become hard, abraded or chipped off. When not in use, the weight must
be positioned
such that the pads are not supporting the full weight of the weight. It is
best to store the weight on
its side.
iv. Rub Tester Instrument Calibration - The Sutherland Rub Tester must first
be
calibrated prior to use. First, turn on the Sutherland Rub Tester by moving
the tester switch to the
"cont" position. When the tester arm is in its position closest to the user,
turn the tester's switch to
the "auto" position. Set the tester to run 5 strokes (back and forth) at a
rate of 42 cycles/minute by
moving the pointer arm on the large dial to the "five" position setting. One
stroke is a single and
complete forward and reverse motion of the weight. The end of the rubbing
block should be in
the position closest to the operator at the beginning and at the end of each
test.
Prepare a test specimen on cardboard sample as described above. In addition,
prepare a
felt on cardboard sample as described above. Both of these samples will be
used for calibration
of the instrument and will not be used in the acquisition of data for the
actual samples.
Place this calibration fibrous structure sample on the base plate of the
tester by slipping
the holes in the board over the hold-down pins. The hold-down pins prevent the
sample from
moving during the test. Clip the calibration felt/cardboard sample onto the
four pound weight
with the cardboard side contacting the pads of the weight. Make sure the
cardboard/felt
combination is resting flat against the weight. Hook this weight onto the
tester arm and gently
place the fibrous structure sample underneath the weight/felt combination. The
end of the weight
closest to the operator must be over the cardboard of the fibrous structure
sample and not the
fibrous structure sample itself. The felt must rest flat on the fibrous
structure sample and must be
in 100% contact with the fibrous structure sample surface. Activate the tester
by depressing the
"push" button.
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Keep a count of the number of strokes and observe and make a mental note of
the starting
and stopping position of the felt covered weight in relationship to the
sample. If the total number
of strokes is five and if the end of the felt covered weight closest to the
operator is over the
cardboard of the fibrous structure sample at the beginning and end of this
test, the tester is
calibrated and ready to use. If the total number of strokes is not five or if
the end of the felt
covered weight closest to the operator is over the actual fibrous structure
sample either at the
beginning or end of the test, repeat this calibration procedure until 5
strokes are counted the end
of the felt covered weight closest to the operator is situated over the
cardboard at the both the
start and end of the test. During the actual testing of samples, monitor and
observe the stroke
count and the starting and stopping point of the felt covered weight.
Recalibrate when necessary.
v. Hunter Color Meter Calibration - Adjust the Hunter Color Difference Meter
for the
black and white standard plates according to the procedures outlined in the
operation manual of
the instrument. Also run the stability check for standardization as well as
the daily color stability
check if this has not been done during the past eight hours. In addition, the
zero reflectance must
be checked and readjusted if necessary. Place the white standard plate on the
sample stage under
the instrument port. Release the sample stage and allow the sample plate to be
raised beneath the
sample port. Using the "L-Y", "a-X", and "b-Z" standardizing knobs, adjust the
instrument to
read the Standard White Plate Values of "L", "a", and "b" when the "L", "a",
and "b" push
buttons are depressed in turn.
vi. Measurement of Samples - The first step in the measurement of lint is to
measure the
Hunter color values of the black felt/cardboard samples prior to being rubbed
on the fibrous
structure sample. The first step in this measurement is to lower the standard
white plate from
under the instrument port of the Hunter color instrument. Center a felt
covered cardboard, with
the arrow pointing to the back of the color meter, on top of the standard
plate. Release the sample
stage, allowing the felt covered cardboard to be raised under the sample port.
Since the felt width is only slightly larger than the viewing area diameter,
make sure the
felt completely covers the viewing area. After confirming complete coverage,
depress the L push
button and wait for the reading to stabilize. Read and record this L value to
the nearest 0.1 unit.
If a D25D2A head is in use, lower the felt covered cardboard and plate, rotate
the felt
covered cardboard 90 degrees so the arrow points to the right side of the
meter. Next, release the
sample stage and check once more to make sure the viewing area is completely
covered with felt.
Depress the L push button. Read and record this value to the nearest 0.1 unit.
For the D25D2M
unit, the recorded value is the Hunter Color L value. For the D25D2A head
where a rotated
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sample reading is also recorded, the Hunter Color L value is the average of
the two recorded
values.
Measure the Hunter Color L values for all of the felt covered cardboards using
this
technique. If the Hunter Color L values are all within 0.3 units of one
another, take the average to
obtain the initial L reading. If the Hunter Color L values are not within the
0.3 units, discard
those felt/cardboard combinations outside the limit. Prepare new samples and
repeat the Hunter
Color L measurement until all samples are within 0.3 units of one another.
For the measurement of the actual fibrous structure sample/cardboard
combinations, place
the fibrous structure sample/cardboard combination on the base plate of the
tester by slipping the
holes in the board over the hold-down pins. The hold-down pins prevent the
sample from moving
during the test. Clip the calibration felt/cardboard sample onto the four
pound weight with the
cardboard side contacting the pads of the weight. Make sure the cardboard/felt
combination is
resting flat against the weight Hook this weight onto the tester arm and
gently place the fibrous
structure sample underneath the weight/felt combination. The end of the weight
closest to the
operator must be over the cardboard of the fibrous structure sample and not
the fibrous structure
sample itself. The felt must rest flat on the fibrous structure sample and
must be in 100% contact
with the fibrous structure sample surface.
Next, activate the tester by depressing the "push" button. At the end of the
five strokes
(back and forth) at a rate of 42 cycles/minute the tester will automatically
stop. Note the stopping
position of the felt covered weight in relation to the sample. If the end of
the felt covered weight
toward the operator is over cardboard, the tester is operating properly. If
the end of the felt
covered weight toward the operator is over sample, disregard this measurement
and recalibrate as
directed above in the Sutherland Rub Tester Calibration section.
Remove the weight with the felt covered cardboard. Inspect the fibrous
structure sample.
If torn, discard the felt and fibrous structure sample and start over. If the
fibrous structure sample
is intact, remove the felt covered cardboard from the weight. Determine the
Hunter Color L value
on the felt covered cardboard as described above for the blank felts. Record
the Hunter Color L
readings for the felt after rubbing. Rub, measure, and record the Hunter Color
L values for all
remaining samples. After all fibrous structure samples have been measured,
remove and discard
all felt. Felts strips are not used again. Cardboards are used until they are
bent, torn, limp, or no
longer have a smooth surface.
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vii. Calculations - Determine the delta L values by subtracting the average
initial L
reading found for the unused felts from each of the measured values for the
first-side surface
and second-side surface sides of the sample as follows.
For samples measured on both surfaces, subtract the average initial L reading
found
for the unused felts from each of the three first-side surface L readings and
each of the three
second-side surface L readings. Calculate the average delta for the three
first-side surface
values. Calculate the average delta for the three second-side surface values.
Subtract the felt
factor from each of these averages. The final results are termed a lint for
the first-side surface
and a lint for the second-side surface of the fibrous structure sample.
By taking the average of the lint value on the first-side surface and the
second-side surface,
the lint is obtained which is applicable to that particular fibrous structure
sample. In other
words, to calculate lint value, the following formula is used:
Lint Value, first-side + Lint Value, second-side
Lint Value =
2
For samples measured only for one surface, subtract the average initial L
reading
found for the unused felts from each of the three L readings. Calculate the
average delta for
the three surface values. Add 1.1 to this average to arrive at the reported
Dry Lint Score for
that particular fibrous structure sample.
The dimensions and values disclosed herein are not to be understood as being
strictly
limited to the exact numerical values recited. Instead, unless otherwise
specified, each such
dimension is intended to mean both the recited value and a functionally
equivalent range
surrounding that value. For example, a dimension disclosed as "40 mm" is
intended to mean
"about 40 mm."
The citation of any document, including any cross referenced or related patent
or
application, is not an admission that it is prior art with respect to any
invention disclosed or
claimed herein or that it alone, or in any combination with any other
reference or references,
teaches, suggests or discloses any such invention. Further, to the extent that
any meaning or
definition of a term in this document conflicts with any meaning or definition
of the same
term in a document cited herein, the meaning or definition assigned to that
term in this
document shall govern.
While particular embodiments of the present invention have been illustrated
and
described, it would be obvious to those skilled in the art that various other
changes and
modifications can be made without departing from the invention described
herein.
