Note: Descriptions are shown in the official language in which they were submitted.
WO 2017/106299 PCT/IIS2016/066587
FLUSHABLE FIBROUS STRUCTURES
FIELD OF THE INVENTION
The present invention relates to flushable fibrous structure products.
BACKGROUND OF THE INVENTION
Flushable fibrous structures, such as toilet tissue and flushable wet wipes,
are well
known. There are numerous characteristics that affect how well the products
exit a toilet bowl.
On one hand, fibrous structures that sink too quickly can form a temporary
plug at the exit of the
toilet bowl, which can in turn affect the ultimate liushability of the
structures. On the other hand,
fibrous structures that float or take a significant amount of time to sink may
not experience a
sufficient level of forces during a flush to draw the fibrous structure toward
and through the exit
of the toilet bowl. The present invention illustrates fibrous structures that
strike an appropriate
balance in view of this dichotomy.
BRIEF DESCRIPTION OF THE DRAWINGS
The following detailed description of specific aspects of the present
invention can be best
understood when read in conjunction with the drawings enclosed herewith.
Fig. I is a schematic of an exemplary prior art milling process useful for
separating
attached trichome fibers from a host plant.
Fig. 2 is a schematic of illustrative process steps according to the present
invention useful
for liberating separated trichome fibers from a feedstock comprising leaves,
stems, and trichome
fibers.
Fig. 3 is a first bar chart that includes flushability results of sanitary
tissue products with
and without a silicone additive.
Fig. 4 is a second bar chart that includes flushability results of sanitary
tissue products
with and without a silicone additive.
Fig. 5 is another her chart that includes flushability results of sanitary
tissue products with
and without trichome fibers.
2
DETAILED DESCRIPTION OF THE INVENTION
The following text sets forth a broad description of numerous different
embodiments of
the present invention. The description is to be construed as exemplary only
and does not
describe every possible embodiment since describing every possible embodiment
would be
impractical, if not impossible. And it will be understood that any feature,
characteristic,
component, composition, ingredient, product, step or methodology described
herein can be
deleted, combined with or substituted for, in whole or part, any other
feature, characteristic,
component, composition, ingredient, product, step or methodology described
herein. Numerous
alternative embodiments could be implemented, using either current technology
or technology
developed after the filing date of this patent, which would still fall within
the scope of the claims.
It should also be understood that, unless a term is expressly defined in this
specification
using the sentence "As used herein, the term ' ___________________________ '
is hereby defined to mean..." or a similar
sentence, there is no intent to limit the meaning of that term, either
expressly or by implication,
beyond its plain or ordinary meaning, and such term should not be interpreted
to be limited in
scope based on any statement made in any section of this patent (other than
the language of the
claims). No term is intended to be essential to the present invention unless
so stated. To the
extent that any term recited in the claims at the end of this patent is
referred to in this patent in a
manner consistent with a single meaning, that is done for sake of clarity only
so as to not confuse
the reader, and it is not intended that such a claim term be limited, by
implication or otherwise, to
that single meaning.
"Fiber" as used herein means an elongate physical structure having an apparent
length
greatly exceeding its apparent diameter, i.e. a length to diameter ratio of at
least about 10. Fibers
having a non-circular cross-section and/or tubular shape are common; the
"diameter" in this case
may be considered to be the diameter of a circle having cross-sectional area
equal to the cross-
sectional area of the fiber. More specifically, as used herein, "fiber" refers
to fibrous structure-
making fibers. The present invention contemplates the use of a variety of
fibrous structure-
making fibers, such as, for example, natural fibers, such as trichome fibers
and/or wood pulp
fibers, or synthetic fibers, or any other suitable fibers, and any combination
thereof
"Fibrous structure" as used herein means a structure that comprises one or
more fibers.
Non-limiting examples of processes for making fibrous structures include known
wet-laid
CA 3005763 2019-12-13
WO 2017/106299 PCT/US2016/066587
3
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 suspension 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 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.
Non-limiting types of fibrous structures according to the present invention
include
conventionally felt-pressed fibrous structures; pattern densified fibrous
structures; and high-bulk,
uncompacted fibrous structures. The fibrous structures may be of a homogenous
or multilayered
(two or three or more layers) construction; and the sanitary tissue products
made therefrom may
be of a single-ply or multi-ply construction.
In one example, the fibrous structure of the present invention is a pattern
densified fibrous
structure characterized by having a relatively high-bulk region of relatively
low fiber density and
an array of densified regions of relatively high fiber density. The high-bulk
field is characterized
as a field of pillow regions. The densified zones are referred to as knuckle
regions. The knuckle
regions exhibit greater density than the pillow 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. Typically, from about 8% to about 65% of the fibrous
structure surface
comprises densified knuckles. The knuckles may exhibit a relative density of
at least 125% of
the density of the high-bulk field. Processes for making pattern densified
fibrous structures are
well known in the art as exemplified in U.S. Patent Nos. 3,301,746; 3,974,025;
4,191,609; and
4,637,859.
The present invention is directed to flushable fibrous structure products,
including
sanitary tissue products. As discussed in the background section above, there
is a relatively
narrow desirable range of floatation/sink time. Fibrous structures that float
can have difficulty
exiting a toilet bowl. And fibrous structures that sink too fast can cause a
plug at the exit point of
a toilet bowl. Thus, the present invention is directed to fibrous structures
and sanitary tissue
CA 03005763 2018-05-17
4
products comprising the same that do not float but sink sufficiently slow when
placed into a toilet
so as not to cause a plug.
Flushability evaluations can be made according to the Flushability Test
methods
described below. These methods can assess toilet bowl clearances during a
flushing event, and
can also assess the float and sink characteristics of a sanitary tissue
product. Independent of the
flushability assessments, the inventors have discovered that contact angle of
a fibrous structure is
one indicator of how well it will flush according to the present invention.
Some fibrous
structures and sanitary tissue embodiments of the present invention have a
contact angle of
greater than or equal to 75 degrees, 80 degrees, 90 degrees, and 100 degrees.
While relatively
high contact angles can be desirable, fibrous structures of the present
invention should not float
indefinitely when placed into a toilet bowl, as it can negatively impact
ultimate flushability of the
structure.
Fibrous structures of the present preferably comprise a fiber blend. The
fibers blends
typically include wood fibers, which can often be referred to as wood pulps
include chemical
pulps, such as haft (sulfate) and sulfite pulps, as well as mechanical and
semi-chemical pulps
including, for example, groundwood, thermomechanical pulp, chemi-mechanical
pulp (CMP),
chemi-thermomechanical pulp (CTMP), neutral semi-chemical sulfite pulp (NSCS).
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 and/or layered web. U.S. Patent Nos. 4,300,981 and
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. The wood pulp fibers may be short (typical of hardwood fibers) or
long (typical of
softwood fibers). Non-limiting 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, and Magnolia. Non-
limiting examples of
long fibers include fibers derived from Pine, Spruce, Fir, Tamarack, Hemlock,
Cypress, and
Cedar. Softwood fibers derived from the
WO 2017/106299 PCT/US2016/066587
k.raft process and originating from mom-northern climates may be preferred.
These are often
referred to as northern softwood kraft (NSK) pulps.
Hydrophobic Fibers
The inventors have discovered that the addition of a percentage of relatively
hydrophobic
fibers to the fiber blend can improve flushability. "Relatively hydrophobic"
as that term is used
herein includes fibers that are generally considered hydrophobic, fibers that
are less hydrophilic
than hardwood and softwood fibers, and naturally hydrophilic fibers that have
been treated to be
less hydrophilic. In one aspect of the present invention, trichome fibers
(discussed in greater
detail below) can be included into the fiber blend as a relatively hydrophobic
fiber that can
improve flushability of the fibrous structure. In one example, the hydrophobic
fibers comprise
fibers harvested from a plant. Other relatively hydrophobic fibers include
synthetic fibers, such
as, for example, wet spun fibers, dry spun fibers, melt spun (including melt
blown) fibers,
synthetic pulp fibers and mixtures thereof. Synthetic fibers may, for example,
be comprised of
cellulose (often referred to as "rayon"); cellulose derivatives such as
esters, ether, or nitrous
derivatives; polyolefins (including polyethylene and polypropylene);
polyesters (including
polyethylene terephthalate); polyamides (often referred to as "nylon");
acrylics; non-cellulosic
polymeric carbohydrates (such as starch, chitin and chitin derivatives such as
chitosan);
polylactic acids, polyhydroxyalkanoates, polycaprolactones, and mixtures
thereof.
Trichome fibers are one exemplary relatively hydrophobic fiber type that can
be utilized
to improve flushability of a fibrous structure. Fibrous structures according
to this invention may
contain from about 0.1% to about 100% and/or from about 0.5% to about 90%
and/or from about
0.5% to about 809b and/or from about 0.5% to about 50% and/or from about 1% to
about 40%
and/or from about 2% to about 30% and/or from about 5% to about 25% by weight
on a dry fiber
basis of trichome fibers.
"Trichome" as used herein means an epidermal attachment of a varying Shape,
structure
and/or function of a non-seed portion of a plant. In one example, a trichome
is an outgrowth of
the epidermis of a non-seed portion of a plant. The outgrowth may extend from
an epidermal
cell. In one embodiment, the outgrowth is a trichome fiber. The outgrowth may
be a hairlike or
bristlelike outgrowth from the epidermis of a plant. The term "individualized
trichome fibers" as
used herein means trichome fibers which have been artificially separated by a
suitable method for
individualizing trichome fibers from their host plant. In other words,
individualized trichome
fibers, as used herein, means that the trichome fibers become separated from a
non-seed portion
WO 2017/106299 PCT/US2016/066587
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of a host plant by some non-naturally occurring action. In one example,
individualized trichome
fibers are artificially separated in a location that is sheltered from nature.
Primarily,
individualized trichome fibers will be fragments or entire trichome fibers
with essentially no
remnant of the host plant attached. However, individualized trichome fibers
can also comprise a
minor fraction of trichome fibers retaining a portion of the host plant still
attached, as well as a
minor fraction of trichome fibers in the form of a plurality of trichome
fibers bound by their
individual attachment to a common remnant of the host plant. Individualized
trichome fibers
may comprise a portion of a pulp or mass further comprising other materials,
including non-
trichome-bearing fragments of the host plant. "Trichome fibers", as that term
is used herein is
interchangeable with the term "individualized trichome fibers" as defined
above.
Individualized trichomes may be converted into chemical derivatives including
but not
limited to cellulose derivatives, for example, regenerated cellulose such as
rayon; cellulose ethers
such as methyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose;
cellulose esters
such as cellulose acetate and cellulose butyrate; and nitrocellulose.
'Individualized trichomes
may also be used in their physical form, usually fibrous, and 'herein referred
to "trichome fibers",
as a component of fibrous structures.
Trichome fibers are different from seed hair fibers in that they are not
attached to seed
portions of a plant. For example, trichome fibers, unlike seed hair fibers,
are not attached to a
seed or a seed pod epidermis. Cotton, kapok, milkweed, and coconut coir are
non-limiting
examples of seed hair fibers. Further, trichome fibers are different from
nonwood bast and/or
core fibers in that they are not attached to the bast, also known as phloem,
or the core, also
known as xylem portions of a nonwood dicotyledonous plant stern. Non-limiting
examples of
plants which have been used to yield nonwood bast fibers and/or nonwood core
fibers include
kenaf, jute, flax, ramie and hemp. Further trichome fibers are different from
monocotyledonous
plant derived fibers such as those derived from cereal straws (wheat, rye,
barley, oat, etc), stalks
(corn, cotton, sorghum, Hesperaloe funifira, etc.), canes (bamboo, bagasse,
etc.), grasses
(esparto, lemon, .sabai, switchgrass, etc), since such monocotyledonous plant
derived fibers are
not attached to an epidermis of a plant. Further, trichome fibers are
different from leaf fibers in
that they do not originate from within the leaf structure. Sisal and abaca are
sometimes liberated
as leaf .fibers. Finally, trichome fibers are different from wood pulp fibers
since wood pulp fibers
are not outgrowths from the epidermis of a plant; namely, a tree. Wood pulp
fibers rather
originate from the secondary xylem portion of the tree stem.
WO 2017/106299 PCT/US2016/066587
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Essentially all plants have trichomes. Those skilled in the art will recognize
that some
plants will have trichomes of sufficient mass fraction and/or the overall
growth rate and/or
robustness of the plant so that they may offer attractive agricultural economy
to make them more
suitable for a large commercial process, such as using them as a source of
chemicals, e.g.
cellulose, or assembling them into fibrous structures, such as disposable
fibrous structures.
Trichomes may have a wide range of morphology and chemical properties. For
example, the
trichomes may be in the form of fibers; namely, trichome fibers. Such trichome
fibers may have
a high length to diameter ratio.
The following sources are offered as non-limiting examples of trichome-hearing
plants
(suitable sources) for obtaining trichomes, especially trichome fibers.
Non-limiting examples of suitable sources for obtaining trichomes, especially
trichome
fibers, are plants in the Labiatae (Lamiaceae) family commonly referred to as
the mint family.
Examples of suitable species in the Labia:fie family include Stachys
byzantina, also
known as Stachys lanata commonly referred to as lamb's ear, woolly betony, or
woundwott.
The term Stachys byzantina as used herein also includes cultivars Stachys
byzantina 'Primrose
Heron', Stachys byzantina 'Helene von Stein' (sometimes referred to as Stachys
byzantina 'Big
Ears'), Stachys byzantina 'Cotton Boll', Stachys byzantina 'Variegated'
(sometimes referred to
as Stachys byzantina 'Striped Phantom'), and Stachys byzantina 'Silver
Carpet'.
Additional examples of suitable species in the Labiatae family include the
arcticus
subspecies of Thymus praecox, commonly referred to as creeping thyme and the
pseudolanuginosus subspecies of Thymus praecox, commonly referred to as wooly
thyme.
Further examples of suitable species in the Labiatae family include several
species in the
genus Salvia (sage), including Salvia leucantha, commonly referred to as the
Mexican bush sage;
Salvia tarahumara, commonly referred to as the grape scented Indian sage;
Salvia apiana,
commonly referred to as white sage; Salvia funereal, commonly referred to as
Death Valley sage;
Salvia saginata, commonly referred to as balsamic sage; and Salvia argentiae,
commonly
referred to as silver sage.
Even further examples of suitable species in the Lablatae family include
Lavandula
lemma, commonly referred to as wooly lavender; Matrublum vulgare, commonly
referred to as
horehound; Plectranthus argentatus, commonly referred to as silver shield; and
Plectranthus
tonzentosa,
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Non-limiting examples of other suitable sources for obtaining trichomes,
especially
trichome fibers are plants in the Asteraceae family commonly referred to as
the sunflower
family.
Examples of suitable species in the Asteraceae family include Artemisia
stelleriana, also
known as silver brocade; Haplopappus inaeronema, also known as the whitestem
goldenbush;
Helichrysum petiolare; Cemaurea maritime, also known as Centaurea gymnocarpa
or dusty
miller; Achillea tomentosum, also known as wooly yarrow; Anapludis
margaritacea, also known
as pearly everlasting; and Encelialarinose, also known as brittle bush.
Additional examples of suitable species in the Asteraceae family include
Senecio
brachyglonis and Senecio hawonhii, the latter also known as Kleinia haivonhii.
Non-limiting examples of other suitable sources for obtaining trichomes,
especially
trichome fibers, are plants in the Scrophulariaceae family commonly referred
to as the figwort or
snapdragon family.
An example of a suitable species in the Scrophtdariaceae family includes
Pedicularis
kanei, also known as the wooly lousewort.
Additional examples of suitable species in the Scrophulariaceae family include
the
mullein species (Verbascum) such as Verbascum hybridiunt, also known as snow
maiden;
Verbascum thapsus, also known as common mullein; Verbascum baldaccii;
Verbascum
bombyciferum; Verbascum broussa; Verbascum Verbascum
dumulsum; Verbasoun
laciniatum; Verbascum lanalum; Verbascum longifolium; Verbascum lychnitis;
Verbascum
olympicum; Verbascum paniculatum; Verbascum phlomoides; Verbascum phoeniceum;
Verbascum speciosum; Verbascum thapsiforme; Verbascum virgaturn; Vethascum
wiedemannianum; and various mullein hybrids including Vethascum 'Helen
Johnson' and
Verbascum Jackie'.'
Further examples of suitable species in the Scrophulariaceae family include
Stemodia
tomentosa and Stemodia durantifolia.
Non-limiting examples of other suitable sources for obtaining trichomes,
especially
trichome fibers include Greyia radikoferi and Greyia flanmaganii plants in the
Greyiaceae
family commonly referred to a the wild bottlebrush
Non-limiting examples of other suitable sources for obtaining trichomes,
especially
trichome fibers include members of the .Fabaceae (legume) family. These
include the Glycine
max, commonly referred to as the soybean, and Trifidium pratense L, commonly
referred to as
medium and/or mammoth red clover.
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Non-limiting examples of other suitable sources for obtaining trichomes,
especially
trichome fibers include members of the Solanaceae family including varieties
of Lycopersicum
esculentum, otherwise known as the common tomato.
Non-limiting examples of other suitable sources for obtaining trichomes,
especially
trichome fibers include members of the Convolvidaceae (morning glory) family,
including
Argyreia nervosa, commonly referred to as the wooly morning glory and
Convolvidus cneorum,
commonly referred to as the bush morning glory.
Non-limiting examples of other suitable sources for obtaining trichomes,
especially
trichome fibers include members of the Malvaceae (mallow) family, including
Anoda cristata,
commonly referred to as spurred anoda and Abutilon theophrasti, commonly
referred to as
velvetleaf.
Non-limiting examples of other suitable sources for obtaining trichomes,
especially
trichome fibers include Buddleia marrubufoliaõ commonly referred to as the
wooly butterfly
bush of the Loganiaceae family; the Casimiroa tetrameria, commonly referred to
as the wooly
leafed sapote of the Rutaceae family; the Ceanothus tomentosus, commonly
referred to as the
wooly leafed mountain !iliac of the Rhamnaceae family; the Philippe Vapelle'
cultivar of
renardii in the Geraniaceae (geranium) family; the Tibotwhina urvilleana,
commonly referred to
as the Brazilian spider flower of the .Melasionzaraceue family; the Tillandsia
recurvata,
commonly referred to as ballmoss of the Bromeliaceae (pineapple) family; the
Hverictun
tomentosum, commonly referred to as the wooly St. John's wort of the
Hvericaceae family; the
Chorizanthe orcuttiatia, commonly referred to as the San Diego spineflower of
the Polygonaceae
family; Eremocatpus setigerus, commonly .referred to as the doveweed of the
Euphorbiaceae or
spurge family; Kcdanchoe tonzentosa, commonly referred to as the panda plant
of the
Crassulaceae family; and Cynodon dactylon, commonly referred to as Bermuda
grass, of the
Poaceae family; and Congea tomentosa, commonly referred to as the shower
orchid, of the
Verbenaceae family.
Suitable trichome-bearing plants are commercially available from nurseries and
other
plant-selling commercial venues. For example, Stachys byzantina may be
purchased and/or
viewed at Blanchette Gardens, Carlisle, MA.
In one example, a trichome fiber suitable for use in the fibrous structures of
the present
invention comprises cellulose. In yet another example, a trichome fiber
suitable for use in the
fibrous structures of the present invention comprises a fatty acid. In still
another example, a
trichome fiber suitable for use in the fibrous structures of the present
invention is hydrophobic.
WO 2017/106299 PCT/US2016/066587
In yet another example, a trichome fiber suitable for use in the fibrous
structures of the present
invention is less hydrophilic that softwood fibers.
Trichome fibers can be liberated from a non-seed portion of a host plant
through various
processes. An exemplary prior art process is shown in Fig. 1, wherein the
process steps in Fig. 1
focus on milling a trichome-containing feedstock of material, and wherein the
process steps in
Fig. 2 focus on disassociating separated trichome fibers from non-desirable
material, classifying,
and collecting trichome fibers useful for making fibrous structures. Referring
to Fig. I, a
feedstock that includes leaves, stems, and attached trichome fibers is fed
into a vacuum system
10 that has two outlets, an upper outlet 12 to collect dust, and a lower
outlet 14 to collect further
processable material 16. The main purpose of vacuum system 10 is to transport
the feedstock
and to begin cleaning the feedstock of dirt, dust, and other waste material.
Material 16 continues
on to a cyclone 18 that also contains a upper outlet 20 for collecting dust,
and a lower outlet 22
that feeds a ham.merrnill 24. Magnets 26 and 28 are included to remove any
metal that has been
introduced into the feedstock via harvesting, transportation, or handling
equipment. Hamme.rmill
24 breaks the leaves and stems up into smaller pieces and separates at least
some of the trichome
fibers from leaves and stems. Referring to Fig. 2, material 30 coming Out of
hammermill. 24 is
then directly or indirectly routed to a screw conveyor 101 to feed a venturi
mechanism 102. A
blower 104 communicates pressurized fluid 105 to venturi. mechanism 102.
Pressurized fluid
105 becomes entrained with the milled feedstock 100 and is directed to a fluid
flow resistor in the
form of a breaker plate 106. Forces encountered because of the venturi
mechanism 102 and
impacting the breaker plate 106 disassociate at least some of the separated
trichome fibers from
the leaf and stern pieces to create a relined feedstock 110.
Trichome fibers can be sorted and collected through various techniques of
processing
refined feedstock 110. As exemplified in Fig. 2, refined feedstock 110 is
communicated to a first
air classifier 112. Screening equipment and air classifying equipment are well
known in the art.
A suitable air classifier is the Hosokawa Alpine 50ATF', sold by Hosokawa
Micron Powder
Systems of Summit, NJ. Other suitable classifiers are available from the Minox
Siebtechnik.
A portion of refined feedstock 110 exits air classifier 112 as a waste stream
114. While a
target of waste stream 114 are the milled stems, milled leaves, and dirt,
inevitably some of the
separated trichome fibers and still attached trichome fibers will be lost
through the waste stream
114. The remaining portion of refined feedstock 110 is routed to a second air
classifier 120
Wherein outlet 122 primarily communicates trichome fiber lines to a first
collection device and
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outlet 124 primarily communicates trichome fibers that are larger than the
fines to a second
collection device.
As noted above, outlet 122 of air classifier 120 allows for the collection of
trichome fiber
fines, which include fibers having a length of less than 100 microns.
Employment of at least
some trichome fibers having a length of less than 100 microns into a fibrous
structure is believed
to impart an increased flushability benefit to a fibrous structure compared to
employment of only
trichome fibers having a length of 100 microns or more. This is because the
shorter fibers have
a larger surface area per weight and therefore play a bigger role in driving
hydrophobicity of the
structure in which they are incorporated. Fibers having a length of less than
100 microns were
essentially making their way into a waste stream in prior art liberating
processes, and thus, were
not collected for incorporation into fibrous structures.
Fiber blends may comprise other fibers, including animal fibers, mineral
fibers, other plant
fibers (in addition to the trichomes of the present invention) and mixtures
thereof. Animal fibers
may, for example, be selected from the group consisting of: wool, silk and
mixtures thereof.
The other plant fibers may, for example, be derived from a plant selected from
the group
consisting of: wood, cotton, cotton linters, flax, sisal, abaca, hemp,
hesperaloe, jute, bamboo,
bagasse, kudzu, corn, sorghum, gourd, agave, loofah and mixtures thereof. In
one example, the
fiber blend comprises softwood fibers, hardwood fibers, and hydrophobic
fibers, such as
trichome fibers.
The fibrous structure may comprise fibers, films and/or foams that comprise a
hydroxyl
polymer and optionally a crosslinking system. Non-limiting examples of
suitable hydroxyl
polymers include j)olyols, such as polyvinyl alcohol, polyvinyl alcohol
derivatives, polyvinyl
alcohol copolymers, starch, starch derivatives, chitosan, chitosan
derivatives, cellulose
derivatives such as cellulose ether and ester derivatives, gums, arabinans,
galactans, proteins and
various other polysaccharides and mixtures thereof. For example, a web of the
fibrous structure
may comprise a continuous or substantially continuous fiber comprising a
starch hydroxyl
polymer and a polyvinyl alcohol hydroxyl polymer produced by dry spinning
and/or solvent
spinning (both unlike wet spinning into a coagulating bath) a composition
comprising the starch
hydroxyl polymer and the polyvinyl alcohol hydroxyl polymer.
The fibrous structure may comprise other additives, such as wet strength
additives,
softening additives, solid additives (such as starch, clays), dry strength
resins, wetting agents, lint
resisting and/or reducing agents, absorbency-enhancing agents, immobilizing
agents, especially
in combination with emollient lotion compositions, antiviral agents including
organic acids,
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antibacterial agents, polyol polyesters, anti migration agents, polyhydroxy
plasticizers and
mixtures thereof. Such other additives may be added to the fiber furnish, the
embryonic fibrous
web and/or the fibrous structure. Such other additives may be present in the
fibrous structure at
any level based on the dry weight of the fibrous structure. The other
additives may be present in
the fibrous structure 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 1.0% by weight, on a dry fibrous structure basis.
Non-limiting types of fibrous structures include conventionally felt-pressed
fibrous
structures; pattern densified fibrous structures; and high-bulk, uncompacted
fibrous structures.
The fibrous structures may be of a homogenous or multilayered (two or three or
more layers)
construction; and the sanitary tissue products made therefrom may be of a
single-ply or multi-ply
construction.
In one example, the fibrous structure is a pattern densified fibrous structure
characterized
by having a relatively high-bulk region of relatively low .fiber density and
an array of densified
regions of relatively high fiber density. The high-bulk field is characterized
as a field of pillow
regions. The densified zones are referred to as knuckle regions. The knuckle
regions exhibit
greater density than the pillow 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.
Typically, from about 8% to about 65% of the fibrous structure surface
comprises densified
knuckles, the knuckles may exhibit a relative density of at least 125% of the
density of the high-
bulk field. Processes for making pattern densified fibrous structures are well
known in the art as
exemplified in U.S. Patent Nos. 3,301,746; 3,974,025; 4,191,609 and 4,637,859.
The fibrous structures of the present invention may be in the form of through-
air-dried
fibrous structures, differential density fibrous structures, differential
basis weight fibrous
structures, wet laid fibrous structures, air laid fibrous structures (examples
of which are described
in U.S. Patent Nos. 3,949,035 and 3,825,381), conventional dried fibrous
structures, creped or
uncreped fibrous structures, patterned-densified or non-patterned-densified
fibrous structures,
compacted or uncompacted fibrous structures, nonwoven fibrous structures
comprising synthetic
or multicomponent fibers, homogeneous or multilayered fibrous structures,
double re-creped
fibrous structures, foreshortened fibrous structures, co-form fibrous
structures (examples of
which are described in U.S. Patent No. 4,100,324) and mixtures thereof.
The fibrous structures may exhibit a substantially uniform density or may
exhibit
differential density regions, in other words regions of high density compared
to other regions
WO 2017/106299 PCT/US2016/066587
13
within the patterned fibrous structure. Typically, when a fibrous structure is
not pressed against a
cylindrical dryer, such as a Yankee dryer, while the fibrous structure is
still wet and supported by
a through-air-drying fabric or by another fabric or when an air laid fibrous
structure is not spot
bonded, the fibrous structure typically exhibits a substantially u.niforn)
density.
The fibrous structures of the present invention may be subjected to any
suitable post
processing including, but not limited to, printing, embossing, calendaring,
slitting, folding,
combining with other fibrous structures, and the like.
Hydrophobic Additive
Alternative to or in addition to including a percentage of relatively
hydrophobic fibers, a
hydrophobic additive can be added to the fibrous structure during the dry end
of the
making/converting of the fibrous structure. Numerous techniques can be
employed to deposit the
additive onto one or more surfaces of the fibrous structure, including, but
not limited to, slot
coating and spraying. Hydrophobic additives can also be included during the
wet end of making
the fibrous structure, such as, for example, including a hydrophobic additive
in a fiber slurry.
In some embodiments, the hydrophobic additive has an HLB value from about 5 to
about
13, or about 7 to about 13. It is believed that additives in this .HLEI value
can control the sinking
time of fibrous structures in a toilet bowl. If the additive has an IHILB
value that is outside of this
range, then the fibrous structure may float or may not significantly affect
the sink time of the
fibrous structure to alter its flushability profile.
A representative, non-limiting list of suitable hydrophobic additives include
OMNIBULK
from Kemira Chemicals and various silicones, including AP6087 (amino silicone)
from Dow
Corning, DC-8566 (amino silicone) from Dow Corning, DC-8800 (polyether
silicone) from Dow
Corning, DC-8166 (amino silicone) from Dow Corning, and MAGN.ASOFT Fluid
(Diarnino
silicone) from Momentive Performance Materials.
"Sanitary tissue product" as used herein means a soft, low density (i.e. <
about 0.15
gicm3) web useful as a wiping implement for post-urinary and post-bowel
movement cleaning
(toilet tissue and wet wipe). The sanitary tissue product may be convolutedly
wound upon itself
about a core or without a core to form a sanitary tissue product roll. The
sanitary tissue products
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 fmm about
30 to 90 g/m2.
In addition, the sanitary tissue product 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
WO 2017/106299 PCT/US2016/066587
14
105 g/m2 and/or from about 60 to 100 g/m2 as measured according to the Basis
Weight Test
Method described herein.
The sanitary tissue products may exhibit a total dry tensile of at least 150
Win and/or from
about 200 gfin to about 1500 Win and/or from about 250 Win to about 850 g/in
as measured
according to the Total Dry Tensile Test Method described herein.
In another example, the sanitary tissue product may exhibit a total dry
tensile of at least
300 Win and/or at least 350 Win and/or at least 400 Win and/or at least 450
Win and/or at least
500 Win and/or from about 500 Win to about 1500 Win and/or from about 550 Win
to about 850
Win and/or from about 600 Win to about 800 Win as measured according to the
Total Dry Tensile
Test Method described herein. In one example, the sanitary tissue product
exhibits a total dry
tensile strength of less than 1000 Win and/or less than 850 Win as measured
according to the
Total Dry Tensile Test Method described herein.
"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).
The following description illustrates a non-limiting approach for the
preparation of a
sanitary tissue product comprising a fibrous structure according to the
present invention on a
pilot-scale Fourdrinier fibrous structure making machine. Individualized
trichomes can be first
prepared from Stachys byzantina bloom stalks consisting of the dried stems,
leaves, and pre-
flowering buds, by processing dried Stacks byz,antina plant matter through
steps as shown in
Figs. 1 and 2 above.
Special care must be taken while processing the trichomes. Sixty pounds of
trichome
fiber is pulped in a 50 gallon pulper by adding water in half amount required
to make a 1%
trichome fiber slurry. This is done to prevent trichome fibers over flowing
and floating on
surface of the water due to lower density and hydrophobic nature of the
trichome fiber. After
mixing and stirring a few minutes, the pulper is stopped and the remaining
trichome fibers are
pushed in while water is added. After pH adjustment, it is pulped for 30
minutes, then dumped in
WO 2017/106299 PCT/US2016/066587
a separate chest for delivery onto the machine headbox. This allows one to
place trichome fibers
in one or more layers, alone or mixed with other fibers, such as hardwood
fibers and/or softwood
fibers. During this particular run, the trichome fibers are added exclusively
on the wire outer
layer as the product is converted wire side up; therefore it is desirable to
add the trichome fibers
to the wire side (the side where the tactile feel senses paper the most).
The aqueous slurry of eucalyptus fibers is prepared at about 3% by weight
using a
conventional repulper. This slurry is also passed through a stock pipe toward
the stock pipe
containing the trichome fiber slurry.
The 1% trichome fiber slurry is combined with the 3% eucalyptus fiber slurry
in a
proportion which yields about 13.3% trichome fibers and 86.7% eucalyptus
fibers. The
stockpipe containing the combined trichome and eucalyptus fiber slurries is
directed toward the
wire layer of headbox of a Fourdrinier machine.
In order to impart temporary wet strength to the finished fibrous structure, a
1%
dispersion of temporary wet strengthening additive (e.g., Fennorez 91
commercially available
from Kem.ira) is prepared and is added to the NSK fiber stock pipe at a rate
sufficient to deliver
0.3% temporary wet strengthening additive based on the dry weight of the NSK
fibers. The
absorption of the temporary wet strengthening additive is enhanced by passing
the treated slurry
through an in-line mixer.
The trichome fiber and eucalyptus fiber slurry is diluted with white water at
the inlet of a
fan pump to a consistency of about 0.15% based on the total weight of the
eucalyptus and
trichome fiber slurry. The NSK fibers, likewise, are diluted with white water
at the inlet of a fan
pump to a consistency of about 0.15% based on the total weight of the NSK
fiber slurry. The
eucalyptus/trichome fiber slurry and the NSK fiber slurry are both directed to
a layered .headbox
capable of maintaining the slurries as separate streams until they are
deposited onto a forming
fabric on the Fourdrinier.
The fibrous structure making machine has a layered headbox having a top
chamber, a
center chamber, and a bottom chamber. The eucalyptus/trichome combined fiber
slurry is
pumped through the top headbox chamber, eucalyptus fiber slurry is pumped
through the bottom
headbox chamber, and, simultaneously, the NSK fiber slurry is pumped through
the center
headbox chamber and delivered in superposed relation onto the Fourdrinier wire
to form thereon
a three-layer embryonic web, of which about 83% is made up of the
eucalyptus/trichome fibers
and 17% is made up of the .NSK fibers. Dewatering occurs through the
Fourdrinier wire and is
assisted by a deflector and vacuum boxes. The Fourdrinier wire is of a 5-shed,
satin weave
WO 2017/106299 PCT/US2016/066587
16
configuration having 87 machine-direction and 76 cross-machine-direction
monofilaments per
inch, respectively. The speed of the Fourdrinier wire is about 750 fpm (feet
per minute).
The embryonic wet web is transferred from the Fourdrinier wire, at a fiber
consistency of
about 15% at the point of transfer, to a patterned drying fabric. The speed of
the patterned drying
fabric is the same as the speed of the Fourdrinier wire. The drying fabric is
designed to yield a
pattern densified tissue with discontinuous low-density deflected areas
arranged within a
continuous network of high density (knuckle) areas. This drying fabric is
formed by casting an
impervious resin surface onto a fiber mesh supporting fabric. The supporting
fabric is a 45 x 52
filament, dual layer mesh. The thickness of the resin cast is about 12 mils
above the supporting
fabric. A suitable process for making the patterned drying fabric is described
in published
application US 2004/0084167 Al.
Further de-watering is accomplished by vacuum assisted drainage until the web
has a
fiber consistency of about 30%.
While remaining in contact with the patterned drying fabric, the web is pre-
dried by air
blow-through pre-dryers to a fiber consistency of about 65% by weight.
After the pre-dryers, the semi-dry web is transferred to the Yankee dryer and
adhered to
the surface of the Yankee dryer with a sprayed creping adhesive. The creping
adhesive is an
aqueous dispersion with the actives consisting of about 22% polyvinyl alcohol,
about 11%
CREPETROL A3025, and about 67% CREPETROL R6390. CREPETROL A3025 and
CREPETROL R6390 are commercially available from Hercules Incorporated of
Wilmington,
Del. The creping adhesive is delivered to the Yankee surface at a rate of
about 0.15% adhesive
solids based on the dry weight of the web. The fiber consistency is increased
to about 97%
before the web is dry creped from the Yankee with a doctor blade.
The doctor blade has a bevel angle of about 25 degrees and is positioned with
respect to
the Yankee dryer to provide an impact angle of about 81 degrees. The Yankee
dryer is operated
at a temperature of about 350 F (177 C) and a speed of about 800 fpm. The
fibrous structure is
wound in a roll using a surface driven reel drum having a surface speed of
about 656 feet per
minute. The fibrous structure may be subsequently converted into a sanitary
tissue product
having a basis weight of from about 10 pounds/3000 square feet about 70
pounds/3000 square
feet.
Toilet Tissue Examples
Sanitary tissue products in the form of toilet tissue were prepared for
contact angle
measurements and flushability assessment. Table 1 below includes a control
toilet tissue
WO 2017/106299 PCT/US2016/066587
17
comprising a blend of NSK fibers, eucalyptus fibers, and a softener additive
("K." designation).
The remaining toilet tissue examples also comprise a fiber blend of NSK fibers
and eucalyptus
fibers along with at least one of trichome fibers, a silicone dry end
additive, and the softener
additive. One can see that the addition of a hydrophobic fiber (trichome)
drives up the contact
angle. One can also see that the addition of silicone also drives up the
contact angle. The
softener additive has an opposite effect on contact angle.
Table 1: Contact Angle
Sample Contact
Angle, degrees
(avg of 5 measurements)
Control + softener additive 68.6
3% trichome fibers 90.3
3% trichorne fibers + softener additive 84.0
5% trichome fibers + 10# of silicone additive 118.0
5% trichome fibers + 10# of silicone additive + softener additive 102.5
7.5% trichome fibers + 7.5# of silicone additive 112.7
7.5%, trichome fibers + softener additive 96.9
10%. trichome fibers 99.9
Additional toilet tissue samples were prepared for flushability testing. The
samples
include a control ("base") that does not contain a silicone additive, and
several other product
samples that contain varying silicone additives. Figs. 3 and 4 show bowl
clearances (multiple
sheets) and sink times (single sheet) of the samples. A few different flush
scenarios were tested,
including 25-sheet loading, 30-sheet loading, and 35-sheet loading. The y-axis
is the percentage
of bowl clearance according to the Flushability Test described below. Note
that the sink times
reported in Figs. 3 and 4 are in seconds and have been multiplied by 5 to
better tit the scale of the
chart. Fig. 5 shows bowl clearances for sanitary tissue products with and
without the inclusion of
trichome fibers.
Table 2, below, shows the effect of including hydrophobic fibers and a
silicone
additive in a fibrous structure and sanitary tissue product comprising the
same. It is desirable to
design a fibrous structure that does not float and that sinks slower than the
control sample: thus,
no faster than 2.5 seconds and/or slower than 2.5 seconds and/or slower than
3.0 seconds and/or
slower than 3.5 seconds.
WO 2017/106299 PCT/US2016/066587
18
Table 2: Sink Time
Sample Sink Time, seconds
Control (including 7.5# softener additive) 2.4
5% trichome fibers + 7.5# softener additive 2.6
5% trichome fibers 3.1
5% trichome fibers + 7.5# of silicone additive 4.0
7.5% trichome t iller\ + 7.5# softener additive 3.7
7.5% trichome fibers 4.5
7.5% trichome fibers + 7.5# silicone additive 4.4
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.
Contact Angle Method
A Fibro DAT 1100 contact angle measurement system was used to measure dynamic
contact angle of the samples. A 4 microliter drop of deionized water is
dispensed onto the
sample by the instrument and contact angle is recorded for a period of 2
minutes. The average
contact angle values reported in Table 1 represent an average of 5 replicate
measurements, each
of which being taken at a 0.1 second reading time.
Flushability Test Method
While numerous different toilet brands and designs can be used for
flushability
assessments, a KOHLER PORTRAIT Lite 6 liter toilet was used for evaluating the
samples
herein. The water supply to the toilet was targeted at 20 C (+1- VC). The
toilet water volume
was also verified by the following check procedure:
WO 2017/106299 PCT/US2016/066587
19
1. Tare a 2 1/2 gallon or a 5 gallon bucket on the Toledo Scale located in the
Flush Lab.
Check to make sure that you are zeroing at the Kg function.
2. Flush toilet to be tested to set the water level in the bowl. Wait for the
toilet to completely
refill before continuing. When the water has stopped flowing out of the
drainline, place
the bucket at the end of the drainline.
3. Flush toilet and catch the water at the end of the drain line. Allow the
water to drain for 2
minutes then remove the bucket from the end of the drainline and take to the
floor scale.
4. Weigh the bucket and record volume on data sheet. Repeat until you have 5
recorded
flushes with an average final flush volume. The flush volume must be within
0.2kg of the
volume the toilet is supposed to flush.
Ten sequential flushes (all at the same sheet count loading) are performed for
each product
sample. The loadings usually begin with a sheet count that is expected to
clear the toilet
successfully in all 10 flushes. The loadings are increased incrementally for
each trial. The
samples are prepared by tearing tissue samples off a roll in strips of 5
sheets each. Each strip is
folded to the size of one sheet, with the ends of the strips folded to the
inside. Each stack is
weighed and the mass recorded before dosing to the toilet.
General nothing instructions:
1. Turn on the water tempering system and make sure that it is set to the
correct
temperature.
2. Once the water in the system is at temperature, flush the specified toilet
to be used in the
testing until the water temperature in the tank is at the specified
temperature + 1.0 C.
These extra flushes can be used to verify the volume of the toilet.
3. Once the toilet has refilled completely, Place each strip of tissue in
the center of the water
spot of the bowl at 10 second intervals. It is important to drop the tissue
flat down into the
water. The tissue should be placed so that the fold is facing the right side
of the toilet. The
next strip should be placed directly on top of and aligned with the previous
piece even if
the previous strip has rotated a bit. It is important to drop the sample from
just above the
piece already in the toilet so that hits squarely, not letting one side touch
the strip in the
toilet ahead of the other side. Following these loading instructions reduces
the variability
of the results.
4. Wait 10 seconds after dosing the final strip before flushing the toilet.
5. Observe the evacuation of the toilet bowl and record the data.
WO 2017/106299 PCT/US2016/066587
6. Wait until the toilet tank is completely refilled and there is no more
water running into the
tank before starting to dose the next loading.
7. Repeat the loading, flushing and data recording for each loading until
the 10 flush trial is
complete.
8. Continue on with the next replicate of that loading or the next loading.
Figs. 3, 4, and 5 show the results with the percentage of the 10 flushing
events clearing the bowl
for each sample.
Total Dry Tensile Strength Test Method
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.
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) (Win)
Peak Elongation (Elongation) (%)
Peak CD TEA (Wet CD TEA) (in-g/in2)
Tangent Modulus (Dry MD Modulus and Dry CD Modulus) (at 1.5g/cm)
CA 03005763 2018-05-17
21
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.
Total Dry Tensile (TDT) = Peak Load MD Tensile (g/in) + Peak Load CD Tensile
(Win)
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 and any patent application or patent to which this application
claims priority or
benefit thereof 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 spirit and scope of the
invention. It is
therefore intended to cover in the appended claims all such changes and
modifications that are
within the scope of this invention.
