U.S. patent application number 17/382725 was filed with the patent office on 2021-11-11 for methods for liberating trichome fibers from portions of a host plant.
The applicant listed for this patent is The Procter & Gamble Company. Invention is credited to Scott Christopher Kreider, Khosrow Parviz Mohammadi.
Application Number | 20210348335 17/382725 |
Document ID | / |
Family ID | 1000005728153 |
Filed Date | 2021-11-11 |
United States Patent
Application |
20210348335 |
Kind Code |
A1 |
Mohammadi; Khosrow Parviz ;
et al. |
November 11, 2021 |
Methods for Liberating Trichome Fibers from Portions of a Host
Plant
Abstract
Improved processes for liberating trichome fibers from non-seed
portions of a trichome-bearing host plant are provided, as well as
inventive fibrous structures comprising trichome fibers.
Inventors: |
Mohammadi; Khosrow Parviz;
(Liberty Township, OH) ; Kreider; Scott Christopher;
(Liberty Township, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Procter & Gamble Company |
Cincinnati |
OH |
US |
|
|
Family ID: |
1000005728153 |
Appl. No.: |
17/382725 |
Filed: |
July 22, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16388986 |
Apr 19, 2019 |
11098451 |
|
|
17382725 |
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|
15378430 |
Dec 14, 2016 |
10309057 |
|
|
16388986 |
|
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62269430 |
Dec 18, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D21H 27/30 20130101;
D21B 1/063 20130101; A47K 10/16 20130101; D21H 11/20 20130101; D21B
1/34 20130101; B32B 29/005 20130101; D21H 11/08 20130101; D21H
27/002 20130101; D21H 11/12 20130101; D21B 1/06 20130101 |
International
Class: |
D21H 11/12 20060101
D21H011/12; D21B 1/06 20060101 D21B001/06; D21B 1/34 20060101
D21B001/34; D21H 27/30 20060101 D21H027/30; B32B 29/00 20060101
B32B029/00; D21H 27/00 20060101 D21H027/00; A47K 10/16 20060101
A47K010/16; D21H 11/08 20060101 D21H011/08; D21H 11/20 20060101
D21H011/20 |
Claims
1. A fibrous structure comprising: a fiber blend that comprises
wood fibers and trichome fibers; wherein at least some of the
trichome fibers have a length that is less than 100 microns;
wherein the fiber blend comprises from about 1% to about 40% of
trichome fibers; wherein the wood fibers comprise both hardwood
fibers and softwood fibers; and wherein the trichome fibers
comprise an L* color value of greater than about 70%.
2. The fibrous structure of claim 1, wherein the trichome fibers
comprise a b* color value of less than about 15%.
3. The fibrous structure of claim 1, wherein the trichome fibers
are derived from a plant in the Stachys genus.
4. The fibrous structure of claim 1, wherein the fiber blend
comprises from about 2% to about 30% of trichome fibers.
5. The fibrous structure of claim 1, wherein the fiber blend
comprises from about 5% to about 25% of trichome fibers.
6. The fibrous structure of claim 1, wherein the trichome fibers
are derived from a plant in the Stachys genus.
7. A single or multi ply sanitary tissue product comprising the
fibrous structure according to claim 1.
8. The sanitary tissue product of claim 7, wherein the fibrous
structure comprises an additive selected from the group consisting
of: wet strength additives, softening agents, and mixtures
thereof.
9. The sanitary tissue product of claim 7, wherein the sanitary
tissue product exhibits a total dry tensile of from about 200 g/in
to about 1000 g/in, as measured according to the Total Dry Tensile
Test Method described herein.
10. The sanitary tissue product of claim 7, wherein the sanitary
tissue product is toilet tissue.
11. The fibrous structure of claim 1, wherein the trichome fibers
are derived from a plant in the Stachys genus.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of, and claims priority
under 35 U.S.C. .sctn. 120 to, U.S. patent application Ser. No.
16/388,986, filed on Apr. 19, 2019, which is a continuation of U.S.
patent application Ser. No. 15/378,430, filed on Dec. 14, 2016, now
U.S. Pat. No. 10,309,057, granted Jun. 4, 2019, which claims the
benefit, under 35 USC .sctn. 119(e), of U.S. Provisional Patent
Application Ser. No. 62/269,430, filed on Dec. 18, 2015, the entire
disclosures of which are fully incorporated by reference
herein.
FIELD OF THE INVENTION
[0002] The present invention relates to methods for liberating
trichome fibers and to fibrous structures comprising individualized
trichome fibers.
BACKGROUND OF THE INVENTION
[0003] Historically, fibrous structures including those that are
used to make sanitary tissue products have been made with softwood
fibers and hardwood fibers. For example, softwood fibers have
typically made up greater than 20% by weight on a dry fiber basis
of through-air-dried fibrous structures. The softwood fibers are
longer fibers than the hardwood fibers and they provide greater
strength properties to the fibrous structures than do the hardwood
fibers. However, softwood fibers typically do not provide the level
of softness benefit provided by hardwood fibers.
[0004] Trichome fibers have been identified as a good substitute
for softwood fibers to provide softness while contributing
sufficient strength to a fibrous structure in which they are
incorporated. Trichomes are epidermal attachments 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. Trichomes may protect the plant
tissues present on a plant. Trichomes may for example protect
leaves and stems from attack by other organisms, particularly
insects or other foraging animals and/or they may regulate light
and/or temperature and/or moisture. They may also produce glands in
the forms of scales, different papills and, in roots, often they
may function to absorb water and/or moisture.
[0005] Individualized trichome fibers can be artificially separated
from portions of their host plant. U.S. Pat. No. 7,811,613
describes a process for liberating trichome fibers that includes a
milling operation of non-seed portions of a trichome-bearing plant
followed by a screening or air classifying step to separate the
trichome fibers from other portions (such as the leaves and stems)
of the host plant. FIGS. 1 and 2 illustrate such a process. A
feedstock of material 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 an
upper outlet 20 for collecting dust, and a lower outlet 22 that
feeds a hammermill 24. Magnets 26 and 28 are included to remove any
metal that has been introduced into the feedstock via harvesting,
transportation, or handling equipment. Hammermill 24 breaks the
leaves and stems up into smaller pieces and separates at least some
of the trichome fibers from leaves and stems. Material 30 coming
out of hammermill 24 is then directly or indirectly routed into a
series of air classifiers 32 and 34, as can be seen in FIG. 2. Air
Classifier 32 has a waste outlet 33 for collecting the small leaf
and stem pieces. Separated trichome fibers are routed to air
classifier 34 and then collected for making fibrous structures.
[0006] Unfortunately, systems such as those described above produce
low yields (mass of feedstock divided by the mass of trichome
fibers collected from air classifier 34); for example, up to around
15%. Low yields discourage commercial leveraging of alternative,
sustainable resources for fibers that can be used in paper
products. One of the reasons for the low yield is that while
trichome fibers can be separated from leaves and stems via the
hammermill, many of the separated fibers are still tangled with or
otherwise associated with the small leaf and stem pieces. These
associated trichome fibers then flow out of the waste outlet 33 and
never make their way into the fiber collection used for making
fibrous structures. The inventors of the present invention have
discovered that one or more additional steps of disassociating
separated fibers from other plant portions significantly increases
trichome fiber yield. The one or more disassociation steps have
also been found to remove dirt and other foreign materials to a
greater level so that the collected trichome fiber masses are
lighter in color and comprise fewer dark specks, making fibrous
structures comprising the processed trichome fibers more consumer
acceptable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The following detailed description of specific embodiments
of the present invention can be best understood when read in
conjunction with the drawings enclosed herewith.
[0008] FIG. 1 is a schematic of an exemplary prior art milling
process.
[0009] FIG. 2 is a schematic of a prior art process as described in
U.S. Pat. No. 7,811,613.
[0010] FIG. 3 is a schematic of illustrative process steps
according to the present invention.
[0011] FIG. 4 is a light micrograph of a leaf and leaf stem
illustrating trichome fibers present on red clover, Trifolium
pratense L.
[0012] FIG. 5 is a light micrograph of a lower stem illustrating
trichome fibers present on red clover, Trifolium pratense L.
[0013] FIG. 6 is a light micrograph of a leaf illustrating trichome
fibers present on dusty miller, Centaurea gymnocarpa.
[0014] FIG. 7 is a light micrograph of individualized trichome
fibers individualized from a leaf of dusty miller, Centaurea
gymnocarpa.
[0015] FIG. 8 is a light micrograph of a basal leaf illustrating
trichome fibers present on silver sage, Salvia argentiae.
[0016] FIG. 9 is a light micrograph of a bloom-stalk leaf
illustrating trichome fibers present in silver sage, Salvia
argentiae.
[0017] FIG. 10 is a light micrograph of a mature leaf illustrating
trichome fibers present on common mullein, Verbascum Thapsus.
[0018] FIG. 11 is a light micrograph of a juvenile leaf
illustrating trichome fibers present on common mullein, Verbascum
Thapsus.
[0019] FIG. 12 is a light micrograph of a perpendicular view of a
leaf illustrating trichome fibers present on wooly betony, Stachys
byzantine.
[0020] FIG. 13 is a light micrograph of a cross-sectional view of a
leaf illustrating trichome fibers present on wooly betony, Stachys
byzantine.
[0021] FIG. 14 is a light micrograph of individualized trichome
fibers in the form of a plurality of trichome fibers bound by their
individual attachment to a common remnant of a host plant, wooly
betony, Stachys byzantina.
[0022] The embodiments set forth in the drawings are illustrative
in nature and not intended to be limiting of the invention defined
by the claims. Moreover, individual features of the drawings and
invention will be more fully apparent and understood in view of the
detailed description.
DETAILED DESCRIPTION OF THE INVENTION
[0023] 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. All
publications and patents cited herein are incorporated herein by
reference.
[0024] 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.
Finally, unless a claim element is defined by reciting the word
"means" and a function without the recital of any structure, it is
not intended that the scope of any claim element be interpreted
based on the application of 35 U.S.C. .sctn. 112, sixth
paragraph.
[0025] 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 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.
[0026] 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.
[0027] 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.
[0028] 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 stem. 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.
[0029] 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 funifera, 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.
[0030] 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.
[0031] 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.
[0032] "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.
[0033] The present invention is directed to improved processes for
liberating trichome fibers from non-seed portions of a
trichome-bearing host plant. Exemplary process steps are shown in
FIG. 3. A feedstock 100 comprising milled leaves, stems, still
attached trichome fibers, and separated trichome fibers is
provided; e.g., via a process such as shown in FIG. 1 and described
above. Various milling apparatuses can be used to break the leaves
and stems into small pieces and to separate at least some of the
trichome fibers. Nonlimiting examples of such devices include a
ball mill, a pin mill, a hammermill, a rotary knife cutter such as
a "Wiley Mill" and/or a "CoMil" sold by Quadro Engineering of
Waterloo, Ontario, Canada.
[0034] Feedstock 100 is fed into 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. In one example,
the entrained pressurized fluid with the feedstock 100 is directed
against the 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 stem pieces to create a refined feedstock 110. Other
approaches beyond a breaker plate can be employed to help
disassociate separated trichome fibers from remaining plant
portions. The fluid flow of the pressurized fluid entrained with
the milled feedstock can be impeded, interrupted, or altered by
various mechanisms, including, for example, in-line mixers, bends
and other directional changes in the fluid flow conduits to
introduce increased frictional losses in the fluid flow, impellers,
in-line screens, and the like. Different types of forces can also
be employed, including impact forces and shear forces, for
example.
[0035] Milled feedstock 100 can alternatively be processed through
other apparatuses prior to being communicated to air classifiers.
Such apparatuses include, but are not limited to, refiners,
beaters, additional millers (dry and wet), homogenizers, pulpers,
cotton millers (also called "pickers" and "openers"), separators,
carders, and deflakers.
[0036] Trichome fibers can be sorted and collected through various
techniques of processing refined feedstock 110. As exemplified in
FIG. 3, 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 50ATP, sold by Hosokawa Micron Powder Systems of
Summit, N.J. Other suitable classifiers are available from the
Minox Siebtechnik.
[0037] 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 fines to a
first collection device and outlet 124 primarily communicates
trichome fibers that are larger than the fines to a second
collection device.
[0038] Processes that include a step of disassociating separated
trichome fibers from leaves and stems can produce trichome fiber
yields higher than previously known processes, such as that
exemplified in FIGS. 1 and 2. The trichome fiber yields from
processes of the present invention can be greater than 15%, 20%,
25%, 30%, 33%, 35%, 37%, and more.
[0039] As noted above in relation to FIG. 3, 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.
Trichome fiber fines can impart a great deal of softness to a
fibrous structure, wherein even small incorporation levels (e.g.,
1%, 2%, 3%, 5%, 7.5%) of the fines can be consumer noticeable in a
final fibrous structure comprising product like a sanitary tissue
product.
[0040] Fiber collections from a prior art process (FIGS. 1 and 2)
and a process according to the present invention (FIGS. 1 and 3)
were analyzed with an L&W STFI Fibermaster instrument. Among
other things, the instrument reports length weighted proportion of
fibers in various length ranges (e.g., 200-500 microns, 500-1500
microns, 1500-3000 microns), and a level of fines reported as a
percentage on a length weighted basis of fibers having a length
below 200 microns. Fiber collections from the prior art process
contained 32% and 33% of fibers in the 200-500 micron range, while
the improved process of the present invention resulted in fiber
collections having 42% and 46% of its fibers in the 200-500 micron
range. And fiber collections from the prior art process contained
10.70% and 11.80% fines, while the improved process of the present
invention had about twice the amount of fines (19.05% and 22.75%).
Thus, the improved processes enable collection of a higher
percentage of small trichome fibers, which can impart various
benefits to fibrous structures comprising the same including, for
example, better softness and better flushability.
[0041] The inventors discovered that processes that include a step
of disassociating separated trichome fibers from leaves and stems
also produce a cleaner mass of collected fibers (including
speck-free trichome fiber masses). As a result trichome fiber
collections via outlet 122 and/or 124 can have L* color values of
greater than or equal to about 70% and/or b* color values of less
than or equal to about 15%. The color and intensity of the
collected trichome fibers can be measured by reflectance
spectrophotometer ASTM standard test methodology. Tristimulus L*,
a*, b* color values are reported in term of the CIE 1976 color
coordinate standard. Processes of the present invention, including
that shown in FIG. 3 and similar process thereto, can eliminate the
need for a washing step prior to incorporating the collected
trichome fibers into a fibrous structure. One of ordinary skill in
the art should appreciate however that an optional washing step can
be used with the inventive processes to drive L* and/or b* values
even higher. For example, an optional washing step can lead to
trichome fiber masses having an L* color value of greater than or
equal to about 80%, and/or a b* color value of less than or equal
to about 10%. In others, the method of the present invention may
further comprise the step of washing the end mass of material
(trichome fiber masses) to increase its L* and/or b* values.
Fibrous structures and sanitary tissue products comprising the same
can have L* values as high as 92% and 95%.
[0042] Feedstock 100 can come from a variety of sources.
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.
[0043] The following sources are offered as non-limiting examples
of trichome-bearing plants (suitable sources) for obtaining
trichomes, especially trichome fibers.
[0044] 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.
[0045] Examples of suitable species in the labiatae family include
Stachys byzantina, also known as Stachys lanata commonly referred
to as lamb's ear, woolly betony, or woundwort. 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`.
[0046] 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.
[0047] 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
sagittata, commonly referred to as balsamic sage; and Salvia
argentiae, commonly referred to as silver sage.
[0048] Even further examples of suitable species in the labiatae
family include Lavandula lanata, commonly referred to as wooly
lavender; Marrubium vulgare, commonly referred to as horehound;
Plectranthus argentatus, commonly referred to as silver shield; and
Plectranthus tomentosa.
[0049] 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.
[0050] Examples of suitable species in the Asteraceae family
include Artemisia stelleriana, also known as silver brocade;
Haplopappus macronema, also known as the whitestem goldenbush;
Helichrysum petiolare; Centaurea maritime, also known as Centaurea
gymnocarpa or dusty miller; Achillea tomentosum, also known as
wooly yarrow; Anaphalis margaritacea, also known as pearly
everlasting; and Encelia farinose, also known as brittle bush.
[0051] Additional examples of suitable species in the Asteraceae
family include Senecio brachyglottis and Senecio haworthii, the
latter also known as Kleinia haworthii.
[0052] 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.
[0053] An example of a suitable species in the Scrophulariaceae
family includes Pedicularis kanei, also known as the wooly
lousewort.
[0054] Additional examples of suitable species in the
Scrophulariaceae family include the mullein species (Verbascum)
such as Verbascum hybridium, also known as snow maiden; Verbascum
thapsus, also known as common mullein; Verbascum baldaccii;
Verbascum bombyciferum; Verbascum broussa; Verbascum chaixii;
Verbascum dumulsum; Verbascum laciniatum; Verbascum lanatum;
Verbascum longifolium; Verbascum lychnitis; Verbascum olympicum;
Verbascum paniculatum; Verbascum phlomoides; Verbascum phoeniceum;
Verbascum speciosum; Verbascum thapsiforme; Verbascum virgatum;
Verbascum wiedemannianum; and various mullein hybrids including
Verbascum `Helen Johnson` and Verbascum `Jackie`.
[0055] Further examples of suitable species in the Scrophulariaceae
family include Stemodia tomentosa and Stemodia durantifolia.
[0056] Non-limiting examples of other suitable sources for
obtaining trichomes, especially trichome fibers include Greyia
radlkoferi and Greyia flanmaganii plants in the Greyiaceae family
commonly referred to as the wild bottlebrush family.
[0057] 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 Trifolium pratense L,
commonly referred to as medium and/or mammoth red clover.
[0058] 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.
[0059] Non-limiting examples of other suitable sources for
obtaining trichomes, especially trichome fibers include members of
the Convolvulaceae (morning glory) family, including Argyreia
nervosa, commonly referred to as the wooly morning glory and
Convolvulus cneorum, commonly referred to as the bush morning
glory.
[0060] 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.
[0061] Non-limiting examples of other suitable sources for
obtaining trichomes, especially trichome fibers include Buddleia
marrubiifolia, 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
liliac of the Rhamnaceae family; the `Philippe Vapelle` cultivar of
renardii in the Geraniaceae (geranium) family; the Tibouchina
urvilleana, commonly referred to as the Brazilian spider flower of
the Melastomataceae family; the Tillandsia recurvata, commonly
referred to as ballmoss of the Bromeliaceae (pineapple) family; the
Hypericum tomentosum, commonly referred to as the wooly St. John's
wort of the Hypericaceae family; the Chorizanthe orcuttiana,
commonly referred to as the San Diego spineflower of the
Polygonaceae family; Eremocarpus setigerus, commonly referred to as
the doveweed of the Euphorbiaceae or spurge family; Kalanchoe
tomentosa, 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.
[0062] 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, Mass. In one example, a trichome
fiber suitable for use in the fibrous structures of the present
invention comprises cellulose. In another example, a trichome fiber
suitable for use in the fibrous structures of the present invention
comprises a fatty acid. In another example, a trichome fiber
suitable for use in the fibrous structures of the present invention
is hydrophobic. In yet another example, a trichome fiber suitable
for use in the fibrous structures of the present invention is less
hydrophilic that softwood fibers. This characteristic of the
trichome fiber may facilitate a reduction in drying temperatures
needed to dry fibrous structures comprising such trichome fiber
and/or may facilitate making the fibrous structures containing such
trichome fiber at a faster rate.
[0063] As shown in FIG. 4, numerous trichomes 10 are present on
this red clover leaf and leaf stem. FIG. 5 shows numerous trichomes
10 present on a red clover lower stem.
[0064] As shown in FIG. 6, a dusty miller leaf is contains numerous
trichomes 10. FIG. 7 shows individualized trichomes 10' obtained
from a dusty miller leaf.
[0065] As shown in FIG. 8, a basal leaf on a silver sage contains
numerous trichomes 10. FIG. 9 shows trichomes 10 present on a
bloom-stalk leaf of a silver sage.
[0066] As shown in FIG. 10, trichomes 10 are present on a mature
leaf of common mullein. FIG. 11 shows trichomes 10 present on a
juvenile leaf of common mullein.
[0067] FIG. 12 shows, via a perpendicular view, trichomes 10
present on a leaf of wooly betony. FIG. 13 is a cross-sectional
view of a leaf of wooly betony containing trichomes 10. FIG. 14
shows individualized trichomes 10' obtained from a wooly betony
leaf.
[0068] Trichome fibers can be liberated through processes of the
present invention for incorporation into fibrous structures.
"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 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.
[0069] The fibrous structures will generally comprise a fiber
blend. The fiber blend may comprise trichome fibers, for example
trichome fibers that exhibit a length of less than 100 microns,
softwood fibers, and/or hardwood fibers. In one example, the fiber
blend comprises at least 1% and/or at least 3% and/or at least 5%
and/or at least 7.5% of trichome fibers. In one example, the fiber
blend comprises at least 1% of trichome fibers, and the wood fibers
comprise both hardwood fibers and softwood fibers. 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 80% 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.
[0070] The fiber blend may also include other fibers besides
trichome fibers. Natural fibrous structure-making fibers useful in
the present invention include 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.
[0071] Wood fibers; often referred to as wood pulps include
chemical pulps, such as kraft (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. Pat.
Nos. 4,300,981 and 3,994,771 are incorporated herein by reference
for the purpose of disclosing 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.
[0072] 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 kraft
process and originating from more-northern climates may be
preferred. These are often referred to as northern softwood kraft
(NSK) pulps.
[0073] Synthetic fibers may be selected from the group consisting
of: 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. In
one example, synthetic fibers may be used as binding agent.
[0074] 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 polyols, 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.
[0075] 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,
antibacterial agents, polyol polyesters, antimigration 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.
[0076] 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.
[0077] 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. Pat.
Nos. 3,301,746, 3,974,025, 4,191,609 and 4,637,859.
[0078] The fibrous structures comprising a trichome fiber in
accordance with 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. Pat. 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. Pat.
No. 4,100,324) and mixtures thereof.
[0079] In one example, the air laid fibrous structure is selected
from the group consisting of thermal bonded air laid (TBAL) fibrous
structures, latex bonded air laid (LBAL) fibrous structures and
mixed bonded air laid (MBAL) fibrous structures.
[0080] 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 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 uniform density.
[0081] 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.
[0082] The fibrous structures of the present invention are
particularly useful for making sanitary tissue products. "Sanitary
tissue product" as used herein means a soft, low density (i.e.
<about 0.15 g/cm.sup.3) web useful as a 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 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/m.sup.2 to about 120 g/m.sup.2 and/or from about
15 g/m.sup.2 to about 110 g/m.sup.2 and/or from about 20 g/m.sup.2
to about 100 g/m.sup.2 and/or from about 30 to 90 g/m.sup.2. In
addition, the sanitary tissue product may exhibit a basis weight
between about 40 g/m.sup.2 to about 120 g/m.sup.2 and/or from about
50 g/m.sup.2 to about 110 g/m.sup.2 and/or from about 55 g/m.sup.2
to about 105 g/m.sup.2 and/or from about 60 to 100 g/m.sup.2 as
measured according to the Basis Weight Test Method described
herein.
[0083] The sanitary tissue products may exhibit a total dry tensile
of at least 150 g/in and/or from about 200 g/in to about 1000 g/in
and/or from about 250 g/in to about 850 g/in as measured according
to the Total Dry Tensile Test Method described herein.
[0084] In another example, the sanitary tissue product may exhibit
a total dry tensile of at least 300 g/in and/or at least 350 g/in
and/or at least 400 g/in and/or at least 450 g/in and/or at least
500 g/in and/or from about 500 g/in to about 1000 g/in and/or from
about 550 g/in to about 850 g/in and/or from about 600 g/in to
about 800 g/in 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
g/in and/or less than 850 g/in as measured according to the Total
Dry Tensile Test Method described herein.
[0085] In another example, the sanitary tissue product may exhibit
a total dry tensile of at least 500 g/in and/or at least 600 g/in
and/or at least 700 g/in and/or at least 800 g/in and/or at least
900 g/in and/or at least 1000 g/in and/or from about 800 g/in to
about 5000 g/in and/or from about 900 g/in to about 3000 g/in
and/or from about 900 g/in to about 2500 g/in and/or from about
1000 g/in to about 2000 g/in as measured according to the Total Dry
Tensile Test Method described herein.
[0086] "Basis Weight" as used herein is the weight per unit area of
a sample reported in lbs./3000 ft.sup.2 or g/m.sup.2. Basis weight
is measured by preparing one or more samples of a certain area
(m.sup.2) 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 (m.sup.2) is measured. The basis weight (g/m.sup.2) is
calculated by dividing the average weight (g) by the average area
of the samples (m.sup.2).
[0087] "Softness" of a fibrous structure according to the present
invention and/or a paper 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 #T4020M-88. Here, samples are preconditioned for 24 hours at
a relative humidity level of 10 to 35% and within a temperature
range of 22.degree. C. to 40.degree. 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.degree.
C. to 24.degree. 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.
[0088] 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 and is incorporated
herein by reference. 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
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:
[0089] 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;
[0090] 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;
[0091] 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:
[0092] 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.
[0093] 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.
[0094] Any suitable process for making fibrous structures known in
the art may be used to make trichome-containing fibrous structures
of the present invention. In one example, the trichome-containing
fibrous structures of the present invention are made by a wet laid
fibrous structure making process. In another example, the
trichome-containing fibrous structures of the present invention are
made by an air laid fibrous structure making process. In one
example, a trichome-containing fibrous structure is made by the
process comprising the steps of: a) preparing a fiber furnish
(slurry) by mixing a trichome with water; b) depositing the fiber
furnish on a foraminous forming surface to form an embryonic
fibrous web; and c) drying the embryonic fibrous web. In one
example, a fiber furnish comprising a trichome, such as a trichome
fiber, is deposited onto a foraminuous forming surface via a
headbox.
[0095] The following Example illustrates a non-limiting example for
the preparation of 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 Stachys byzantina plant matter through steps as
shown in FIGS. 1 and 3 above.
[0096] 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 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).
[0097] 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.
[0098] 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.
[0099] In order to impart temporary wet strength to the finished
fibrous structure, a 1% dispersion of temporary wet strengthening
additive (e.g., Fennorez 91.RTM. commercially available from
Kemira) 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.
[0100] 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.
[0101] "DC 2310" antifoam is dripped into the wirepit to control
foam to maintain whitewater levels of 10 ppm of antifoam.
[0102] 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 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).
[0103] 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.times.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 A1.
[0104] Further de-watering is accomplished by vacuum assisted
drainage until the web has a fiber consistency of about 30%.
[0105] 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.
[0106] 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.
[0107] 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.degree. F. (177.degree. 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 two-ply sanitary tissue product having a basis weight of
about 50 g/m.sup.2.
Test Methods
[0108] 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.degree.
F..+-.4.degree. F. (about 23.degree. C..+-.2.2.degree. 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.
Total Dry Tensile Strength Test Method
[0109] 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.
[0110] 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.
[0111] 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.
[0112] 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:
[0113] Peak Load Tensile (Tensile Strength) (g/in)
[0114] Peak Elongation (Elongation) (%)
[0115] Peak CD TEA (Wet CD TEA) (in-g/in.sup.2)
[0116] Tangent Modulus (Dry MD Modulus and Dry CD Modulus) (at 15
g/cm)
[0117] 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 (g/in)
[0118] 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."
[0119] Every document cited herein, 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 hereby incorporated herein by reference in its entirety
unless expressly excluded or otherwise limited. The citation of any
document 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
incorporated by reference, the meaning or definition assigned to
that term in this document shall govern.
[0120] 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.
* * * * *