Note: Descriptions are shown in the official language in which they were submitted.
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PATTERNED FIBROUS STRUCTURES
FIELD OF THE INVENTION
The present invention relates to patterned fibrous structures, more
particularly to
fibrous structures that comprise a pattern that conveys to a user a
characteristic of the
fibrous structure and/or single- or multi-ply sanitary tissue product
comprising such a
patterned fibrous structure and methods for making same.
BACKGROUND OF THE INVENTION
Some consumers of fibrous structures and/or sanitary tissue products
comprising
fibrous structures, such as toilet tissue, paper towels and/or facial tissue,
desire for their
fibrous structures and/or sanitary tissue products to convey characteristics
of the fibrous
structures and/or sanitary tissue products by a visually recognizable pattern.
For
example, some consumers desire to have both visually recognizable softness and
strength
characteristics conveyed to them via their fibrous structures and/or sanitary
tissue
products.
Conventionally, such softness and strength characteristics have been perceived
as
being diametrically opposed. For example, the softer a fibrous structure was,
the less
strong it should be and vice versa. Accordingly, fibrous structure and/or
sanitary tissue
product manufacturers tried to convey either softness characteristics or
strength
characteristics, but not both in the same fibrous structure and/or sanitary
tissue product.
Accordingly, a long felt need existed to identify a fibrous structure and/or
sanitary
tissue product that conveyed both visually recognizable softness and strength
characteristics.
SUMMARY OF THE INVENTION
The present invention fulfills the need described above by providing a
patterned
fibrous structure that conveys to a user both visually recognizable softness
and strength
characteristics.
In one example of the present invention, a fibrous structure comprising a
visually
recognizable softness region and a visually recognizable strength region, is
provided.
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In another example of the present invention, an embossed fibrous structure
comprising a visually recognizable softness region and a visually recognizable
strength
region, wherein the visually recognizable strength region comprises a
plurality of
embossments and the visually recognizable softness region comprises less
embossments
that the visually recognizable strength region, is provided.
In yet another example of the present invention, an embossed fibrous structure
comprising a visually recognizable softness region and a visually recognizable
strength
region, wherein the visually recognizable softness region is void of
embossments and the
visually recognizable strength region comprises an embossment, is provided.
In even another example of the present invention, an embossed fibrous
structure
comprising a visually recognizable softness region and a visually recognizable
strength
region, wherein the fibrous structure essentially consists of a plurality of
embossments,
wherein the plurality of embossments exhibit a substantially similar shape, is
provided.
In still another example, a single- or multi-ply sanitary tissue product
comprising
a fibrous structure according to the present invention, is provided.
In still yet another example, a method for making a fibrous structure
according to
the present invention, is provided.
Accordingly, the present invention provides a fibrous structure and/or
sanitary
tissue product comprising a visually recognizable softness region and a
visually
recognizable strength region and methods for making same.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a plan view of one example of a fibrous structure in accordance with
the
present invention; and
Fig. 2 is an enlarged cross sectional view of the fibrous structure shown in
Fig. 1
taken along line 2-2.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
"Fibrous structure" and/or "Web" as used herein means a substrate formed from
non-woven fibers. The fibrous structure of the present invention may be made
by any
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suitable process, such as wet-laid, air-laid, spunbond processes. The fibrous
structure
may be in the form of one or more plies suitable for incorporation into a
sanitary tissue
product and/or may be in the form of non-woven garments, such as surgical
garments
including surgical shoe covers, and/or non-woven sanitary tissue products such
as
surgical towels and wipes.
An embryonic fibrous web can be typically prepared from an aqueous dispersion
of fibers, though dispersions in liquids other than water can be used. Such a
liquid
dispersion of fibers is oftentimes called a fibrous slurry. The fibers can be
dispersed in
the carrier liquid to have a consistency of from about 0.1% to about 0.3%. It
is believed
that the present invention can also be applicable to moist forming operations
where the
fibers are dispersed in a carrier liquid to have a consistency less than about
50%, more
preferably less than about 10%.
Alternatively, an embryonic fibrous web can be prepared using air laid
technology
wherein a composition of fibers, (not typically dispersed in a liquid) are
deposited onto a
surface, such as a forming member, such that an embryonic web is formed.
The fibrous structures of the present invention may have physical properties,
such
as dry tensile strength, wet tensile strength, caliper, basis weight, density,
opacity, wet
burst, decay rate, softness, bulk, lint and sidedness suitable to consumers
for fibrous
structures used in sanitary tissue products and/or known by those skilled in
the art to be
suitable for fibrous structures used in sanitary tissue products.
"Fiber" 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.
More specifically, as used herein, "fiber" refers to papermaking fibers. The
present
invention contemplates the use of a variety of papermaking fibers, such as,
for example,
natural fibers or synthetic fibers, or any other suitable fibers, and any
combination
thereof. 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
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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. Nos. 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, and bagasse can be used in this invention. Synthetic fibers
such as rayon
and other polymeric fibers such as polypropylene, polyethylene, polyester,
polyolefm,
polyethylene terephthalate and nylon and various hydroxyl polymers, can be
used. The
polymeric fibers can be produced by spunbond processes, meltblown processes,
and other
suitable methods known in the art.
The fibers may be short or long (e.g., NSK fibers). Nonlimiting examples of
short
fibers include fibers derived from a fiber source selected from the group
consisting of
Acacia, Eucalyptus, Maple, Oak, Aspen, Birch, Cottonwood, Alder, Ash, Cherry,
Elm,
Hickory, Poplar, Gum, Walnut, Locust, Sycamore, Beech, Catalpa, Sassafras,
Gmelina,
Albizia, Anthocephalus, Magnolia, Bagasse, Flax, Hemp, Kenaf and mixtures
thereof.
"Fibrous famish" as used herein means a composition of fibers. In one example,
the fibrous furnish may comprise fibers and a liquid, such as water.
"Sanitary tissue product" as used herein means a single- or mufti-ply wiping
implement for post-urinary and post-bowel movement cleaning (toilet tissue),
for
otorhinolaryngological discharges (facial tissue), and multi-functional
absorbent and
cleaning uses (absorbent towels).
The sanitary tissue products of the present invention may have physical
properties, such as dry tensile strength, wet tensile strength, caliper, basis
weight, density,
opacity, wet burst, decay rate, softness, bulk, lint and sidedness suitable to
consumers for
use as sanitary tissue products ancVor known by those skilled in the art to be
suitable for
use as sanitary tissue products.
=
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"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. Basis weight is measured by preparing one or more
samples of a
certain area (m2) and weighing the sample(s) of a fibrous structure according
to the
present invention and/or a sanitary tissue product comprising such fibrous
structure on a
top loading balance with a minimum resolution of 0.01 g. The balance is
protected from
air drafts and other disturbances using a draft shield. Weights are recorded
when the
readings on the balance become constant. The average weight (g) is calculated
and the
average area of the samples (m2) is measured. The basis weight (g/m2) is
calculated by
dividing the average weight (g) by the average area of the samples (m2).
"Machine Direction" or "MD" as used herein means the direction parallel to the
flow of the fibrous structure through the papermaking machine and/or product
manufacturing equipment.
"Cross Machine Direction" or "CD" as used herein means the direction
perpendicular to the machine direction in the same plane of the fibrous
structure and/or
sanitary tissue product comprising the fibrous structure.
"Dry Tensile Strength" (or simply "Tensile Strength" as used herein) of a
fibrous
structure of the present invention and/or a sanitary tissue product comprising
such fibrous
structure is measured as follows. One (1) inch by five (5) inch (2.5 cm X 12.7
cm) strips
of fibrous structure and/or sanitary tissue product comprising such fibrous
structure are
provided. The strip is placed on an electronic tensile tester Model 1122
commercially
available from Instron Corp., Canton, Massachusetts in a conditioned room at a
temperature of 73 F 4 F (about 28 C 2.2 C) and a relative humidity of 50%
10%.
The crosshead speed of the tensile tester is 2.0 inches per minute (about 5.1
cm/minute)
and the gauge length is 4.0 inches (about 10.2 cm). The Dry Tensile Strength
can be
measured in any direction by this method. The "Total Dry Tensile Strength" or
"TDT" is
the special case determined by the arithmetic total of MD and CD tensile
strengths of the
strips.
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"Caliper" as used herein means the macroscopic thickness of a sample. Caliper
of
a sample of fibrous structure according to the present invention is determined
by cutting a
sample of the 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
(20.3 cm2). The sample is confined between a horizontal flat surface and the
load foot
Loading surface. The load foot loading surface applies a confining pressure to
th.e sample
of 15.5 g/cm2 (about 0.21 psi). 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
millimeters.
"Apparent Density" or "Density" as used herein means the basis weight of a
sample divided by the caliper with appropriate conversions incorporated
therein.
Apparent density used herein has the units g/cm3.
"Softness" of a fibrous structure according to the present invention and/or a
sanitary tissue product comprising such fibrous structure is determined as
follows.
Ideally, prior to softness testing, the samples to be tested should be
conditioned according
to Tappi Method 1fT4020M-88. Here, samples are preconditioned for 24 hours at
a
relative humidity level of 10 to 35% and within a temperature range of 22 C to
40 C.
After this preconditioning step, samples should be conditioned for 24 hours at
a relative
humidity of 48% to 52% and within a temperature range of 22 C to 24 C.
Ideally, the
softness panel testing should take place within the confines of a constant
temperature and
humidity room. If this is not feasible, all samples, including the controls,
should
experience identical environmental exposure conditions.
Softness testing is performed as a paired comparison in a form similar to that
described in "Manual on Sensory Testing Methods", ASTM Special 'Technical
Publication 434, published by the American Society For Testing and Materials
1968.
Softness is evaluated by subjective testing using what
is referred to as a Paired Difference Test. The method employs a standard
external to the
test material itself. For tactile perceived softness two samples are presented
such that the
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subject cannot see the samples, and the subject is required to choose one of
them on the
basis of tactile softness. The result of the test is reported in what is
referred to as Panel
Score Unit (PSU). With respect to softness testing to obtain the softness data
reported
herein in PSU, a number of softness panel tests are performed. In each test
ten practiced
softness judges are asked to rate the relative softness of three sets of
paired samples. The
pairs of samples are judged one pair at a time by each judge: one sample of
each pair
being designated X and the other Y. Briefly, each X sample is graded against
its paired Y
sample as follows:
1. a grade of plus one is given if X is judged to may be a little softer than
Y, and a
grade of minus one is given if Y is judged to may be a little softer than X;
2. a grade of plus two is given if X is judged to surely be a little softer
than Y, and
a grade of minus two is given if Y is judged to surely be a little softer than
X;
3. a grade of plus three is given to X if it is judged to be a lot softer than
Y, and a
grade of minus three is given if Y is judged to be a lot softer than X; and,
lastly:
4. a grade of plus four is given to X if it is judged to be a whole lot softer
than Y,
and a grade of minus 4 is given if Y is judged to be a whole lot softer than
X.
The grades are averaged and the resultant value is in units of PSU. The
resulting
data are considered the results of one panel test. If more than one sample
pair is evaluated
then all sample pairs are rank ordered according to their grades by paired
statistical
analysis. Then, the rank is shifted up or down in value as required to give a
zero PSU
value to which ever sample is chosen to be the zero-base standard. The other
samples
then have plus or minus values as determined by their relative grades with
respect to the
zero base standard. The number of panel tests performed and averaged is such
that about
0.2 PSU represents a significant difference in subjectively perceived
softness.
"Ply" or "Plies" as used herein means an individual fibrous structure
optionally to
be disposed in a substantially contiguous, face-to-face relationship with
other plies,
forming a multiple ply fibrous structure. It is also contemplated that a
single fibrous
structure can effectively form two "plies" or multiple "plies", for example,
by being
folded on itself.
The fibrous structure and/or sanitary tissue product of the invention may be a
single ply web or may be one ply or a multi-ply structure. A multi-ply fibrous
structure
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may be comprised of multiple plies of a fibrous structure of the present
invention or of a
combination of a plies, at least one of which is a fibrous structure ply of
the present
invention.
"User" as used herein means a consumer and/or purchaser of a fibrous structure
and/or sanitary tissue product, preferably a purchaser.
"Characteristic" as used herein means a quality or property inherent in a
fibrous
structure and/or sanitary tissue product. Aesthetics of a fibrous structure
and/or sanitary
tissue product are not a characteristic as defined herein. Nonlimiting
examples of such
characteristics include softness, absorbency, cleaning ability and/or
strength.
"Visually recognizable" as used herein as it pertains to a characteristic of a
fibrous
structure and/or sanitary tissue product means that by visual inspection of
the fibrous
structure and/or sanitary tissue product and/or via touching of the fibrous
structure and/or
sanitary tissue product, the user perceives that fibrous structure and/or
sanitary tissue
product as having a characteristic.
"Embossment" as used herein means a deformation of the fibrous structure or
portion of the fibrous structure in the Z-plane such that the surface of the
fibrous structure
comprises a protrusion or a depression. The embossment may be made by
conventional
embossing procedures known in the art or they may be made by forming the
fibrous
structure on a deflection member such as described in U.S. Pat. No. 4,637,859
and/or on
an imprinting carrier fabric as described in U.S. Pat. Nos. 3,301,746,
3,821,068,
3,974,025, 3,573,164, 3,473,576, 4,239,065 and 4,528,239. Embossments
according to
=the present invention may exhibit a dry structural height of at least about
100 pm and/or
at least about 150 pm and/or at least about 200 pm and/or at least about 250
p,m and/or at
least about 300 pm and/or at least about 400 gm and/or at least about 500 pm
and/or at
least about 600 pm as measured by the Dry-Wet Structural Height Test Method.
Embossments according to the present invention may exhibit a ratio of greatest
geometric dimension to minimum geometric dimension (often referred to as an
aspect
ratio) of less than about 50:1 and/or less than about 30:1 and/or less than
about 15:1
and/or less than about 10:1 and/or less than about 5:1 and/or less than about
2:1 and/or
about 1:1. The embossments may be dots and/or dashes. A plurality of
embossments
may combine to form a "macro" pattern on the fibrous structure surface that
encompasses
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and/or covers less than the entire surface of the fibrous structure. In
addition to the
embossments, there may be other deformations (protrusions or depressions) that
are less
visible on the fibrous structure that encompass and/or cover almost the entire
surface of
the fibrous structure. Such other deformations form a "micro" pattern on the
fibrous
structure surface.
"Signature element" as used herein means a design that has a shape more
complex than just a straight line, dot, dash or other simple shape.
Nonlimiting examples
of signature elements include flowers, hearts, and other user recognizable
unitary designs.
Signature elements may be signature bosses as described in U.S. Patent No.
5,620,776 to
Schulz.
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 and/or Sanitary Tissue Product:
The present invention is applicable to fibrous structures in general,
including but
not limited to conventionally felt-pressed fibrous structures; pattern
densified fibrous
structures; through-air-dried fibrous structuresõ differential density fibrous
structures,
wet laid fibrous structures, air laid fibrous structures, conventional fibrous
structures,
meltblown fibrous structures, spunbond fibrous structures, rotary spun fibrous
structures,
high-bulk, uncompacted fibrous structures and mixtures thereof. The fibrous
structures
may be of a homogenous or multilayered construction; and the sanitary tissue
products
made therefrom may be of a single-ply or multi-ply construction.
The fibrous structures may be made with a fibrous furnish that produces a
single
layer embryonic fibrous web or a fibrous furnish that produces a multi-layer
embryonic
fibrous web.
The fibrous structure and/or sanitary tissue product comprises one or more
plies of
fibrous structure. The fibrous structure and/or sanitary tissue product may be
in
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individual sheet form or may be in roll form. If in roll form, the fibrous
structure and/or
sanitary tissue product may comprise a core upon which the one or more plies
of fibrous
structure are convolutely wound.
The fibrous structure and/or sanitary tissue product and/or plies from which
the
fibrous structure and/or sanitary tissue product is derived may be
foreshortened, such as
via creping, or non-forshortened, such as not creping; creped from a
cylindrical dryer
with a creping doctor blade, removed from a cylindrical dryer without the use
of a
creping doctor blade, or made without a cylindrical dryer.
The fibrous structure and/or sanitary tissue products of the present invention
are
useful in paper, especially sanitary tissue sanitary tissue products
including, but not
limited to: conventionally felt-pressed tissue paper; through-air dried tissue
paper; pattern
densified tissue paper; and high-bulk, uncompacted tissue paper. The tissue
paper may be
of a homogenous or multilayered construction; and tissue sanitary tissue
products in
accordance with the present invention are of a multi-ply construction. The
tissue paper
preferably has a basis weight of between about 10 g/m2 and about 120 g/m2, and
density
of about 0.60 g/cc or less. Preferably, the basis weight will be below about
35 g/m2; and
the density will be about 0.30 g/cc or less. Most preferably, the density will
be between
about 0.04 g/cc and about 0.20 g/cc as measured by the Basis Weight Method
described
herein.
The fibrous structure and/or sanitary tissue product may be made with a
fibrous
furnish that produces a single layer embryonic fibrous web or a fibrous
furnish that
produces a multi-layer embryonic fibrous web.
The fibrous structure and/or sanitary tissue product may comprise an adhesive,
such as a ply bond adhesive.
The fibrous structures of the present invention and/or sanitary tissue
products
comprising such fibrous structures may have a basis weight of between about 10
g/m2 to
about 120 g/m2 and/or from about 14 g/m2 to about 80 g/m2 and/or from about 20
g/m2 to
about 60 g/m2.
The fibrous structures of the present invention and/or sanitary tissue
products
comprising such fibrous structures may have a total dry tensile strength of
greater than
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about 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).
The fibrous structures of the present invention and/or sanitary tissue
products
comprising such fibrous structures may have a density of about 0.60 g/cc or
less and/or
about 0.30 g/cc or less and/or from about 0.04 g/cc to about 0.20 g/cc.
In one embodiment, the fibrous structure of the present invention is a pattern
densified fibrous structure characterized by having a relatively high-bulk
field of
relatively low fiber density and an array of densified zones of relatively
high fiber
density. The high-bulk field is alternatively characterized as a field of
pillow regions. The
densified zones are alternatively referred to as knuckle regions. The
densified zones may
be discretely spaced within the high-bulk field or may be interconnected,
either fully or
partially, within the high-bulk field. Processes for making pattern densified
fibrous
structures are well known in the art as exemplified in U.S. Pat. Nos.
3,301,746,
3,974,025, 4,191,609 and 4,637,859.
In general, pattern densified fibrous structures are preferably prepared by
depositing a papermaking furnish on a foraminous forming wire such as a
Fourdrinier
wire to form a wet fibrous structure and then juxtaposing the fibrous
structure against a
three-dimensional substrate comprising an array of supports. The fibrous
structure is
pressed against the three-dimensional substrate, thereby resulting in
densified zones in the
fibrous structure at the locations geographically corresponding to the points
of contact
between the array of supports and the wet fibrous structure. The remainder of
the fibrous
structure not compressed during this operation is referred to as the high-bulk
field. This
high-bulk field can be further dedensified by application of fluid pressure,
such as with a
vacuum type device or a blow-through dryer, or by mechanically pressing the
fibrous
structure against the array of supports of the three-dimensional substrate.
The fibrous
structure is dewatered, and optionally predried, in such a manner so as to
substantially
avoid compression of the high-bulk field. This is preferably accomplished by
fluid
pressure, such as with a vacuum type device or blow-through dryer, or
alternately by
mechanically pressing the fibrous structure against an array of supports of
the three-
dimensional substrate wherein the high-bulk field is not compressed. The
operations of
dewatering, optional predrying and formation of the densified zones may be
integrated or
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partially integrated to reduce the total number of processing steps performed.
Subsequent
to formation of the densified zones, dewatering, and optional predrying, the
fibrous
structure is dried to completion, preferably still avoiding mechanical
pressing.
In one example, a fibrous structure 10 according to the present invention, as
shown in Fig. 1, comprises a surface 12 and a visually recognizable softness
region 14
and a visually recognizable strength region 16. The visually recognizable
strength region
16 may comprise one or more embossments 18. In one example, the visually
recognizable strength region 16 comprises a plurality of embossments 18. The
visually
recognizable softness region 14 may comprise no embossments 18 and/or fewer
embossments 18 than the visually recognizable strength region 16.
The fibrous structure 10 may comprise a plurality of visually recognizable
softness regions 14 and/or a plurality of visually recognizable strength
regions 16. Each
individual visually recognizable softness region 14 may be visually similar to
another
individual visually recognizable softness region 14 or they may be visually
different from
one another. For example, one individual visually recognizable softness region
14 may
essentially consists of no embossments 18 and another may consist of a
plurality of
embossments 18.
A visually recognizable softness region 14 may be void of embossments 18,
however, it may contain deformations that form a "micro" pattern.
A visually recognizable softness region 14 may be void of signature elements.
The embossments 18 may be combined to form a "stitch" appearance within a
visually recognizable strength region 16.
A visually recognizable softness region 14 may appear to be a pillow that is
dispersed throughout a stitched portions (visually recognizable strength
regions 16 for
example).
A fibrous structure surface area ratio of visually recognizable softness
regions 14
to visually recognizable strength regions 16 may be at least about 1 :2 and/or
at least about
1:3 and/or at least about 1:4 and/or at least about 1:5. For example, the
fibrous structure
surface are ratio of visually recognizable softness regions 14 to visually
recognizable
strength regions 16 may be from about 1:10 to about 1:2 and/or from about 1:8
to about
1:2.5 and/or from about 1:6 to about 1:3 and/or from about 1:5 to about 1:3.
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A representative cross section of the fibrous structure 10 taken along line 2-
2 is
represented in Fig. 2. Fig. 2 shows the fibrous structure 10 and a plurality
of
embossments 18. The fibrous structure 10 comprises at least one fiber 20. A
plurality of
fibers 20 are shown in the embodiment of the fibrous structure 10. As shown in
Figs. 1
and 2, the embossments 18 may be domes.
As shown in Fig. 2, the embossments 18 appear to extend from (protrude from) a
plane 22 of the fibrous structure 10 toward an imaginary observer looking in
the direction
of arrow B. When viewed by an imaginary observer looking in the direction
indicated by
arrow T, the embossments 18 appear to be cavities or dimples or depressions.
The
portions of the fibrous structure 10 forming the embossments 18 can be intact;
however,
the portions of the fibrous structure 10 forming the embossments 18 can
comprise one or
more holes or openings extending essentially through the fibrous structure 10.
In the fibrous structures of the present invention, at least one of the
embossments
may at least retain at least one of its dry properties such as its structural
shape, height and
the like after being wetted, such as after being saturated with water. For
example, the
embossments may retain at least 10% and/or 20% arid/or 30% and/or 40% and/or
50%
and/or 60% of its dry structural height as measured according to the Dry-Wet
Structural
Height Test Method described herein. In one embodiment, the embossment retains
at
least about 100% (even adding structural height to be greater than the dry
height of the
embossment) of its dry structural height as measured according to the Dry-Wet
Structural
Height Test Method described herein.
Fibrous Structure Additives
The fibrous structures of the present invention may comprise, in addition to
fibers,
an optional additive selected from the group consisting of permanent and/or
temporary
wet strength resins, dry strength resins, wetting agents, lint resisting
agents, absorbency-
enhancing agents, immobilizing agents, especially in combination with
emollient lotion
compositions, antiviral agents including organic acids, antibacterial agents,
polyol
polyesters, antimigration agents, polyhydroxy plasticizers, softening agents,
lotions and
mixtures thereof. Such optional additives may be added to the fiber furnish,
the
embryonic fibrous web and/or the fibrous structure.
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Such optional additives may be present in the fibrous structures at any level
based
on the dry weight of the fibrous structure.
The optional additives may be present in the fibrous structures at a level of
from
about 0.001 to about 50% and/or from about 0.001 to about 20% and/or from
about 0.01
to about 5% and/or from about 0.03 to about 3% and/or from about 0.1 to about
1.096 by
weight, on a dry fibrous structure basis.
Processes for Making Fibrous Structures
The fibrous structures of the present invention may be made by any suitable
process known in the art.
In one example of a process for making a fibrous structure of the present
invention, the process comprises the step of forming a fibrous structure that
comprises a
visually recognizable softness region and a visually recognizable strength
region.
In another example of a process for making a fibrous structure of the present
invention, the process comprises the step of embossing a fibrous structure
such that the
fibrous structure comprises a visually recognizable softness region and a
visually
recognizable strength region.
The fibrous structures of the present invention may be made by a process
wlierein
a fibrous furnish is applied to a first foraminous member to produce an
embryonic fibrous
web. The embryonic fibrous web may then come into contact with a second
foraminous
member that comprises a deflection member to produce a visually recognizable
softness
region and a visually recognizable strength region within an intermediate
fibrous web.
The intermediate fibrous web may then be further dried to form a fibrous
structure of the
present invention.
The fibrous structure may be subjected to any other suitable post processing
steps
such as calendering and/or embossing and/or converting.
TEST METHOD
Dry-Wet Structural Height Test Method
The GFM Primos Optical Profiler system measures the surface height of a sample
using the digital micro-mirror pattern projection technique. The result of the
analysis is a
map of surface height (z) vs. xy displacement. The system has a field of view
of 27 X 22
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mm with an xy resolution of 21 microns. The height resolution should be set to
between
0.10 and 1.00 micron. The height range is 64,000 times the resolution.
Dry samples require no preparation prior to measurement.
To prepare a wet sample, a 11.33 cm (4.5 inch) wide by 20.32 cm (8 inch) long
strip of a fibrous structure or sanitary tissue product to be tested is
prepared. First, the
sample is measured dry as described below. Holding one end of the sample
vertically by
the corners, a 10.16 cm (4 inch) long portion of the sample (1/2 of the length
of the
sample) at the distal end from where the sample is being held by the corners
is dipped
slowly and carefully into a pool of water. After the dipped portion of the
sample is fully
saturated, the saturated portion of the sample is removed from the water and
dewutered by
carefully laying the saturated portion of the sample on a dry sheet of Bounty
paper towel
avoiding any folds or wrinkles in the tissue. After 20 seconds the portion of
the sample
being dewatered is carefully removed from the sheet of paper towel and placed
on a
second dry sheet of Bounty paper towel for 20 seconds. A third dry sheet of
Bounty
paper towel is similarly used for an additional 20 seconds. Still while
handling the portion
of the sample that was not saturated, the portion of the sample that was
saturated is
carefully laid over a stainless steel square of size 130 x 130 x 2mm with a
cut out of 90 x
90mm in the center. If necessary, the sample can be very slightly tensioned so
that when
the stainless steel square is lying on a flat surface the fibrous structure or
sanitary tissue
product does not sag and/or touch the flat surface. Slightly touching the
portion of the
sample that was saturated where it contacts the steel square serves to tack
the portion of
the sample to the square and prevents further movement. The sheet is allowed_
to air dry
for an additional 2 minutes prior to measurement as described below.
To measure a fibrous structure sample or sanitary tissue product sample do the
following:
1. Turn on the cold light source. The settings on the cold light source should
be
4 and C, which should give a reading of 3000K on the display;
2. Turn on the computer, monitor and printer and open the ODSCAD 4.14
Software.
3. Select "Start Measurement" icon from the Primos taskbar and then click the
"Live Pic" button.
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4. Place the sample under the projection head, center the features of interest
within the field of view of the live image, and adjust the distance for best
focus.
5. Click the "Pattern" button repeatedly to project one of several focusing
patterns to aid in achieving the best focus (the softwarecross hair should
align
with the projected cross hair when optimal focus is achieved). Position the
projection head to be normal to the sample surface.
6. For dry samples, with a permanent marker, place small dots on the sample at
the corners of the illumination square. For the wet samples, use the four
previous marks to realign the features of interest with the field of view.
7. Adjust image brightness by changing the aperture on the lens through the
hole
in the side of the projector head and/or altering the camera "gain" setting on
the screen. Do not set the gain higher than 7 to control the amount of
electronic noise. When the illumination is optimum, the red circle at bottom
of the screen labeled 1Ø" will turn green.
8. Select Standard measurement type.
9. Click on the "Measure" button. This will freeze on the live image on the
screen and, simultaneously, the image will be captured and digitized. It is
important to keep the sample still during this time to avoid blurring of the
captured images. The images will be captured in approximately 20 seconds.
10. If the height image is satisfactory, save the image to a computer file
with
".omc" extension. This will also save the camera image file ".kam".
11. To move the data into the analysis portion of the software, click on the
clipboard/man icon.
12. Now, click on the icon "Draw lines" or "Draw freehand line" as needed. For
samples where the raised structures lie in a straight line, select the
starting and
ending line points with the mouse so that the marked line traverses several
features. If the raised structures are not on a straight line, use the
freehand line
tool to mark points in the centers of the structures such that the structures
will
be connected with a curved line. Once the line is created, select "Show
sectional line diagram" to create a plot of the height versus distance along
the
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17
line. Use the "Vertical distance" tool to mark a point in the baseline region
between structures, and a point at the top oldie structure and record the
height
calculated. Repeat the measurement for each structure along the line. The
average height of the features is reported in micron units.
All documents cited in the Detailed Description of the Invention are
not to be
considered as an admission that it is prior art with respect to the present
invention. Terms
or phrases defined herein are controlling even if such tains or phrases are
defmed
differently in the = documents.
While particular examples 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.
